VOL.36 NO. 4 WINTER 2017/18 A Division of Valeant ...world-renowned UCSF immunologist Abul K. Abbas, MD) that launched his groundbreaking series of discoveries, he took a less well-traveled

Focus on ResearchAdipose Stem Cells—Understanding Them and TheirPotential Value for Aesthetic and Regenerative MedicineIvona Percec, MD, PhD Assistant Professor of Surgery, Department of Surgery,Division of Plastic Surgery; Director, Basic Science Research, Plastic Surgery; Perelman School of Medicine, University of Pennsylvania

Dr. Percec always knew she would be a clinician and a scientist. She chose plastic

surgery as her clinicalspecialty because sheloves the combinationof working with herhands, repairing aes-thetic and relevantfunctional deficits, andthe challenging varietyof problems and bodyareas that she is able toaddress. And when she joined the faculty atthe University of Pennsylvania, she estab-lished her lab and dedicated it to exploringhuman autologous fat grafts—her favoritemulti-tasking tool in plastic surgery—at themolecular level.

She is fascinated with autologous subcu-taneous fat, which entered the surgical toolbox as a corrective filler in 1893 (see boxon page 14). “It has so many advantages, so many clinical applications and beneficialeffects, that in the operating room we call itliquid gold,” she says. Access is easy. Supply is abundant. Adipose stem cells (ASCs) arehigh in number without requiring special

ichael D. Rosenblum, MD,PhD, associate professor in the department of derma-

tology at the University of California, San Francisco, is both a practicing dermatologistand an immunologist. He has been makingstartling discoveries about regulatory T cells—Tregs—in the skin that initially took him bycomplete surprise. He had realized that newinformation would emerge simply becausehis areas of interest—immune regulationrather than activation, and in the affected tis-sue (skin, in this case) rather than in lymphoidstructures—had not yet received serious research attention. But Rosenblum was not

prepared for results that upended conven-tional concepts of T-cell immunology.

Choosing His FocusRosenblum’s passion for immunology

had been sparked during college in the late1990s, and crystallized when he came acrossThe Transformed Cell: Unlocking the Mysteriesof Cancer by Dr. Steven A. Rosenberg, the innovative cancer immunologist, surgeon, and melanoma specialist at the NCI who has developed several personalized anti-cancerimmunotherapies. Rosenblum modified hisdirection from scientist to physician-scientist,

ultimately choosing dermatology. The skin is prone to a number of inflammatory and autoimmune dis-eases. And as our major barrier to the outside world, all of the skin’s protective mechanisms clearly inter-face with the immune system.

When Rosenblum began hispost-doctoral research (working withworld-renowned UCSF immunologistAbul K. Abbas, MD) that launched hisgroundbreaking series of discoveries,he took a less well-traveled road andearmarked Tregs within the skin forhis primary study. Tregs express a protein called Foxp3, which is uniqueto these cells and critical in regulat-ing inflammation. When Foxp3 hadbeen discovered in 2001—also calledscurfin then—it became apparentthat it binds the DNA of inflammatorycytokines and represses their tran-scription. And loss of Foxp3’s func-tion due to mutations was associatedwith significant autoimmune diseasein mice and humans.

Skin-Resident Tregs:A Powerful Multi-tasking Force for Immune Balance and Tissue Renewals

(Continued on page 11)

M

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Tregs and hair follicle stem cells. Immunofluorescent close-up of Foxp3+ Tregs (red stain, with white arrows) shows subpop-ulation of bulge-associated Tregs closely aligned with HFSCs inmouse telogen skin. (Green-stained hair keratin K-15 is expressedin the hair follicle above the bulb; DAPI is a fluorescent blue stain.)(Reprinted with permission from Cell. See Suggested Readingsfor citation.) (Continued on page 2)

2 Winter 2017/18 Dermatology Foundation

“Most of the seminal work in immunol-ogy, though, focused on activating an immuneresponse, on how to create an immune re-sponse against something like cancers and infections,” Rosenblum explains. “Since acti-vation occurs in lymphoid structures, a lot was learned about the activation dynamicsthere. But I had appreciated very early on,” he continues, “that many times when we wantthe immune system not to respond—it oftennot only responds anyway, it responds too vigorously. Autoimmune diseases are a primeexample. Yet we know very little about howimmune responses are controlled in the tis-

sues where they actually occur,” Rosenblumadds. Few had studied how immune re-sponses are controlled in peripheral tissuessuch as skin—until Rosenblum made this his goal.

He turned his attention to Tregs in theskin—both human and mouse. And hewanted to find out what they do there, howthey do it, what can go wrong—and how theyget there in the first place. “We’ve been find-ing that these cells do a number of things toregulate the immune system and inflamma-tion in the skin,” Rosenblum says. “But some of the most high impact work we have been

able to do over the last several years is to showthat these cells actually have other func-tions—functions outside of their ability to sup-press immune responses. And this waspreviously either not known, or not very wellappreciated. These cells are multi-taskers,”Rosenblum states. Ultimately this should leadto knowledge that can be exploited for therapeutic benefit.

Mouse vs Human Overall, the human relevance of data

gathered from studying mice can be as low as8% of observations. Against this general cau-tion, it is clear that human skin and mouseskin are profoundly different, and most dramatically when it comes to the hair cycle.It is brief, rapid, and synchronous for mice, and very much the opposite for humans.

Keenly aware of this reality, Rosenblumviews his mouse data as provisional until hehas either validated it in human tissue or de-termined that humans are different. He triesto keep his research moving in the right direction by “going back and forth betweenmouse and man.” They usually begin withhuman tissue samples, and once they havediscovered pathways that they think are important in human disease, they do the functional biology in mice as it is impossibleto do this in humans outside of a clinical trial.

A major focus in Rosenblum’s laboratorynow is the development and use of human-ized mouse models. They are genetically mod-ified to be selectively immunodeficient so thatthey will accept human tissue and a humanimmune system. This enables the study ofhuman immune responses using mice, andRosenblum says that “they are proving to be avaluable tool for modeling human autoim-munity and chronic inflammation. The basicimmunobiology of human tissue is readilystudied in these models.”

The lab has evolved to the point wheretheir study of the regulatory immune systemhas achieved a rough balance, with studiesusing human and mouse tissue split roughly40% vs 60%. Although most of Rosenblum’spublications until now are based on observa-tions in mice, he has “a flurry of publicationsscheduled to appear that contain a substan-tial amount of human data—the major path-ways that we discovered in human skin andthen have been modeling in mice.”

Regulatory Memory Cells Are Permanent Residents in the Skin

Immune homeostasis in tissues isachieved through a delicate balance betweenpathogenic T-cell responses directed at tissue-specific antigens and the ability of that tissueto inhibit these responses. But the mecha-nisms by which tissues and the immune sys-tem communicate to establish and maintainimmune homeostasis had been a mystery.That something is going on in the tissue to

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diminish pathological inflammatory re-sponses is suggested by the attenuation ofsymptoms in repeated flares of autoimmunediseases and by the desensitization processwhen specific allergens or self-antigens are repeatedly injected in the skin.

To study how immune responses are reg-ulated in skin, Rosenblum needed a mousemodel that allowed him to set the stage, thenwatch to see what would happen. He neededthe ability to introduce an immunostimula-tory self-antigen only in the skin, and then beable to turn its presence on and off at will. He wanted to bring this new self-antigensilently into the skin, turn it onto see how the initial immuneresponse to it is generated,then turn it off to see if themeter resets to zero or not, turnit on again to see if it’s simply arepeat of the initial response or something different, and re-peat this to see how the im-mune response is regulatedover time.

Rosenblum engineered a mouse using ovalbumin(Ova)—the major protein con-stituent of chicken egg whitesand a standard antigen for immunization research—as the self-antigen,as this glycoprotein is sufficiently large andcomplex to be mildly immunogenic. He wasable to mimic the pattern of tissue-specificself-antigen expression in mice and humans,maintaining the continuous presence of Ovain the thymus while turning it on and off in theskin. Ova delivered to the skin carried a tetra-cycline-activated receptor, so the antigen appeared when tetracycline was added to themouse food and disappeared when the tetra-cycline was stopped.

The initial presence of Ova induced apronounced inflammatory dermatitis despitethe significant presence of Ova-specific Tregcells. Ultimately, it resolved spontaneously despite continued antigen expression in theskin. Rosenblum showed that when this engi-neered self-antigen was turned on in the skin,Treg cells there became activated, proliferated,and differentiated into more potent suppres-sors that mediated the resolution of the autoimmune activity. Then these activated Treg cells remained primed to attenuate sub-sequent autoimmune reactions when Ovawas turned on again.

Rosenblum realized that tissues that haveundergone autoimmune inflammatory reac-tions develop a property that serves to limitthe severity of future such reactions. He calledit regulatory memory, and the cells enabling itare the Tregs that survive after the initial encounter. They not only possess memory of the self-antigen—and thus are called mem-ory regulatory T cells (mTregs)—but they

have acquired an increased ability to sup-press inflammation if and when this antigen reappears.

As with the more familiar T cells, theTreg’s life history begins with generation in thethymus, then activation in the periphery, proliferation and differentiation into func-tionally more active cells, and then survival as memory populations.

Parsing the Biology of mTregs Once Rosenblum realized that the

skin-based encounter between Tregs and aself-antigen generates a population of skin-

resident mTregs that remainsin the skin just in case this anti-gen reappears, he wanted toidentify the factors enablingthem to stay.

Tregs carry receptors forIL-2 and some have the recep-tor for IL-7. When it comes toTregs that develop in the thy-mus and return to secondarylymphoid tissues, both cy-tokines are involved in theirdevelopment from naïve CD4+

T cells and then in their main-tenance. But when all of theaction takes place in the skin,

the roles for these two cytokines are moretighty scripted. IL-2 is essential for generatingTregs from their peripheral naïve CD4+ T cellprecursors. Then IL-7 acts independently tomaintain some mTreg populations in the skin.

Rosenblum also learned that once theantigen is turned off, and thus no immune reg-ulatory action is required, the mTregs localizepreferentially to hair follicles—specifically, in the dermis surrounding the lower hair fol-licle segments. Later, this observation wouldturn out to be the first step in a momentous discovery.

Where Do Skin Tregs Really Come From?

Next, Rosenblum wanted to determine whether the antigen-specific Tregs that appearin the skin are derived in the thymus and then migrate to where they are needed, or whetherthe entire process can take place within theskin. He continued working with Ova riggedas a self-antigen, but instead of enabling hismice to produce their own T-cell-mediated re-sponse as he had done before, he transferredexisting Ova-positive effector T cells (Teffs)from mice that had been engineered to produce T cells with a distinctive molecularsignature. This way, any Treg cells derived from them would be easily distinguishablefrom immune cells produced by the host mice.So once the Ova-induced inflammatory response began and signaled the need for a regulatory counterbalance, if Treg cells appearing on the scene carried the host’s molecular signature, then the track was

thymus to skin. But if they bore the donormouse signature, they clearly had evolved on-site, in the skin, from the donor’s effector T cells. This time, adding or stopping doxycy-cline in the host mouse food turned Ova’spresence on or off, and enabled Rosenblumto track events in the host mouse skin whenthese donor Teff cells first appear, the timeuntil resolution, and what occurs when Ova istransient or persistent.

The Ova-specific donor Teffs induced aninflammatory dermatitis within 2 weeks aftertransfer, then stopped producing inflamma-tory cytokines after 2 weeks. Ova remainedturned on. The inflammatory disease contin-ued, fatal to 30% of the mice, and then resolved spontaneously after 40 days despitethe continued presence of Ova and the donor

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Sponsored byOrtho DermatologicsA Division of Valeant Pharmaceuticals North America LLC

Editors-in-ChiefLindy Fox, MDAssociate Professor of DermatologyUniversity of California, San Francisco

Mary M. Tomayko, MD, PhDAssistant Professor of DermatologyYale School of Medicine, New Haven, CT

Heidi A. Waldorf, MDDirector, Laser and Cosmetic DermatologyThe Mount Sinai Medical Center, New York, NY

Executive DirectorSandra Rahn Benz

Deputy Executive DirectorChristine M. BorisPlease address correspondence to:Editors-in-ChiefDermatology Focusc/o The Dermatology Foundation1560 Sherman AvenueEvanston, Illinois 60201Tel: 847-328-2256 Fax: 847-328-0509e-mail: [email protected]

Published for the Dermatology Foundation byRobert B. GoetzDesigner, ProductionSheila Sperber Haas, PhDManaging Editor, Writer

This issue of Dermatology Focus is distributed without charge through an educational grant from Ortho Dermatologics.The opinions expressed in this publication do not necessarily reflect those of the Dermatology Foundation or Ortho Dermatologics.©Copyright 2018 by the Dermatology Foundation

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Michael D. Rosenblum, MD

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Dr. Schneiderman has maintained a bustlingand varied medical dermatology practice in Syosset,Long Island, outside of Manhattan, for 40 years and it continues to excite him. “I relish receiving patients who are more complex, more challenging,”he says. Known for his work with com-plicated patients, Dr. Schneidermanoften receives referrals from internistsand other dermatologists and con-sults for several nearby hospitals. He gives each patient “time, and mybest intellectual effort. The greatestgratification is finding the problem and fixing it,” he says. But this is justone facet of what he does.

During most of his career, Dr.Schneiderman has also been a part-time teacher. For more than 40 years,he has taught a weekly session at Columbia University Medical Center, using his extensive collection of kodachromes to challenge the resi-dents on differential diagnoses, then teaches at thebedside during inpatient rounds. For 31 years, Dr. Schneiderman has held monthly educational sessions at Yale University. For the last ten years,he has also traveled on a quarterly basis to teachthe residents at the University of Virginia (UVA),where he completed his internal medicine and dermatology residencies. A former student says “he was critical to the foundation of our clinical expert-ise. His mentorship is authentic and deep-seated.”

Dr. Schneiderman came to dermatology via

an atypical route. “I didn’t pursue dermatology,” he recalls. “It was dermatologists who pursued me!” Two chance encounters developed into lasting relationships with “a profound impact” on his career. During his medical residency at UVA,

Dr. Schneiderman happened to meetsecond-year dermatology resident Dr. Ken Greer, who invited him tolook at patients with him. “He piquedmy interest and curiosity.” After hismedical residency, Dr. Schneidermanworked for the Public Health Service,then at the NIH, before beginning hisdermatology residency at UVA. “Onmy first day at the NIH I met Dr. RickEdelson, who asked if I was free towork in his lab with him.” After Dr.Schneiderman returned to New

York, Dr. Edelson invited him to teach weekly at Columbia, and later on a monthly basis at Yale.

Dr. Schneiderman is also an author. He and Dr.Marc Grossman coauthored the seminal A Clinician’sGuide to Differential Diagnosis in Dermatology, with the second edition about to appear.

A colleague describes Dr. Schneiderman’scontributions to the specialty. For decades, “he has graced his work as a teacher and aphysician with his exceptional generosity oftime, talent, and resources.” Dr. Schneidermanviews himself as a “very lucky person. I haveworked with the smartest and most wonderfulphysicians. And I’m all the better for it.”

The Dermatology Foundation pays annual tribute to dermatologists whose exemplary capabilities and dedication havehelped to make the specialty what it is today. Presentation of the 2017 awards will be a highlight of the DF AnnualMeeting on Saturday, February 17 in San Diego, CA. The leaders and role models being honored by their peers are:

Clark W. Finnerud Award—Paul I. Schneiderman, MDDiscovery Award—Luis A. Diaz, MD, and John R. Stanley, MD

Lifetime Career Educator Award—Ilona J. Frieden, MDPractitioner of the Year—Lisa A. Garner, MD

(Drs. Diaz, Garner, and Stanley will be highlighted in the Spring issue.)

2017 Clark W. Finnerud Award: Paul I. Schneiderman, MDHonoring the exceptional clinician who is simultaneously a dedicated and highly effective part-time teacher.

DF Honors Excellence in Dermatology


“I love pediatric dermatology!” exclaims Dr. Frieden, a world-renowned specialist in children’s skin diseases with a substantial rolein putting this subspecialty on the map. She is professor of Pediatrics and Dermatology at theUniversity of California, San Francisco (UCSF),where she completed her pediatrics and dermatology residencies, and is now vice-chair ofDermatology and chief of the Division of PediatricDermatology. She founded a multidisciplinary Vascular Anomalies Clinic at UCSF in1991. A decade later she founded the Hemangioma Investigator Group, a seminally important international research consortium.

While her pediatric training led toan interest in pediatric dermatology,Dr. Frieden’s passion for her subspe-cialty was further ignited in 1983 dur-ing a 3-month Pediatric Dermatologyelective with Dr. Nancy Esterly—oneof the founders of pediatric dermatol-ogy and arguably the founder of academic pediatric dermatology—at Children’s Memorial Hospital in Chicago. She also found Dr. Esterly to be truly inspirational—an excellentphysician, a humble and curious person, and awonderful role model, particularly for women entering the field. “It was the transformational moment in my career, and why I am who I amtoday,” Dr. Frieden states. “Nan lit a fire within me, and helped me find my voice as a physician.”

Dr. Frieden’s career-long dedication to teachingand mentoring is well documented. She has servedas a medical student and resident advisor, estab-lished the pediatric dermatology fellowship program

at UCSF (in 2000), and has helped direct the der-matology department’s Junior Faculty MentoringProgram. She joined the Mentoring Committee ofthe Women’s Dermatologic Society at its inceptionin 1993 and received its Mentor of the Year awardin 2005. When the AAD’s Academic DermatologyLeadership Program (ADLP) was established in2005, she became a mentor in that program, helpingto provide long-distance mentoring for early-careeracademic dermatologists. In 2012, Dr. Frieden helped

found the Pediatric Dermatology Research Alliance (PeDRA) to fostercollaborative research, and serves as a young-investigator mentor intheir mentoring program.

Dr. Frieden has also publishedextensively, held significant electedpositions in specialty organizations,and is ending a long tenure as co-editor of Pediatric Dermatology.She co-authored the authoritativetextbook in neonatal dermatology.

Dr. Frieden’s influence on thoseentering her subspecialty has become legendary.One of her mentees says: “I could not have imag-ined the tremendous impact this would have onme. I was inspired by Dr. Frieden and her work.She helped me crystallize my goals and openedmy world in ways I would never have expected.”Another mentee explains, “I spent a month withDr. Frieden during my residency to expand my knowledge and experience with children. That month changed the course of my career.Two years later I returned to do a pediatric dermatology fellowship at UCSF—and havebeen here ever since!”

2017 Lifetime Career Educator Award: Ilona J. Frieden, MD

Recognizing an academic dermatologist with a career-long history of dedicated service as a mentor, role model, and inspirational teacher.

DF Honors Excellence in Dermatology

T cells targeting it. Resolution reflected thegeneration and progressive expansion ofFoxp3+ Tregs derived from donor T cells, aprocess anchored entirely within the skin. The abiding convention that Tregs were a rel-atively homogeneous population generatedexclusively in the thymus and migrating to peripheral areas of need was now history.

Then Rosenblum and his team wanted to see if the duration of antigen exposure influences the final Teff/Treg balance whenthe mice are examined 60–80 days after re-ceiving the donor’s Ova-specific Teff cells.Turning Ova off after just 7 days left Teffs in themajority. But after persistent exposure—leav-ing Ova on for 60 days—Tregs dominated at ~80% of the mix. The Treg numbers were actually the same in both situations, but with persistent antigen exposure, the Teff population had plummeted.

“These studies highlight the essential roleof peripherally generated Tregs in regulatinglocal pathologic immune responses,” Rosen-blum points out. “They also emphasize theability of Tregs to maintain their function inthe face of constant encounter with a self-antigen, and this may lead us to a better understanding of the pathogenesis of au-toimmune disease. Elucidating the criticalpathways that control the Teff/Treg balancemay provide insight into the pathogenesis oftissue-specific autoimmunity.”

Tregs in Human Skin—The First Assessment

Now it was time to see if the observationsin mouse skin held true for human skin aswell. Before Rosenblum and his team couldbegin their assessment, though, they had to de-vise a way to digest skin samples gentlyenough to enable isolation of a suffcient num-ber of undamaged leukocytes for study, elimi-nating the need for growth factors and daysof culture that distorted the cellular land-scape. Applying their new method overnightto surgically discarded skin samples from

healthy patients revealed that ~20% of theCD4+ T cells in adult skin express Foxp3—ie,they are Tregs. And the almost uniform presence of the memory marker CD45RO ex-pressed by these Tregs meant they had previ-ously seen antigen outside of the thymus—inperipheral tissue— consistent with a memoryT cell phenotype. Rosenblum was able todemonstrate that these mTregs were activatedmemory cells, and that they do not migrateout of the skin.

In a particularly critical parallel, whenthese human mTregs were not involved in im-munoregulatory activity, they preferentially localized to hair follicles in close proximity to the follicular epithelium. In line with this,flow cytometric quantification showed thatskin with high hair density—the scalp andface—had significantly higher percentages ofTregs than areas of low hair density (see graphat left).

In total, this first informed exploration ofmTregs in human skin documented a spec-trum of distinctive identifying characteristics.This applied to cell surface marker expression,cytokine production, in situ localization, T-cellreceptor, and functional capacity. These residents in human skin are clearly a uniquesubset of Tregs.

Rosenblum had access to punch biop-sies from psoriasis patients with active disease,and wanted to see how chronically inflamedand nonlesional skin compared to skin fromhealthy individuals when it comes to im-munoregulation. He and his team optimizedtheir skin digestion protocol further to providea sufficient number of cells from 4-mm punchbiopsies. Compared to nonlesional skin, themTregs in lesional skin were more numerous,highly proliferative, and produced low levelsof IL-17. Their role in the disease process remains to be explored.

Multi-tasking TregsBoth mouse and human skin contain a

particularly large number of tissue-residentTregs, which makes sense given that the skinis an organ of the immune system and our immediate interface with the environment.Given the broad scope of the skin’s essentialprotective functions and the fact that this Tregpopulation remains permanently in the skin,the possibility arises that these cells—so criti-cal for immune homeostasis—may also haveother important functions in the skin. Rosen-blum found several possibilities particularlycompelling for his initial explorations: ensur-ing effective wound healing (because of theshared involvement with the EGFR—epider-mal growth factor receptor—pathway); con-trol of hair follicle stem cell behavior(because the hair follicle is where Tregs clus-ter); and safeguarding the skin’s commensalbacteria (essential to health, they need to beprotected from immune attack).

Wound HealingBecause the skin is highly susceptible to

traumatic injury, wound healing is a criticalprotective function. Wound healing is medi-ated by multiple cell types and molecularpathways, with the EGFR pathway—whichstimulates both epidermal and dermal regen-eration—playing a major role in both. Rosen-blum noted an intriguing molecularintersection between wound healing andTregs in the skin. AREG—the growth factoramphiregulin—is the EGFR ligand. It is alsoexpressed by Tregs that reside in muscle andlung, and enhances repair in these tissuesafter injury.

Rosenblum considered two ways inwhich the skin’s Tregs might be involved inwound healing support. “Because they play amajor role in mediating skin immune home-ostasis, we set out to determine whether theyhelp to attenuate wound-associated inflam-mation,” he says. “We also wanted to see if theyuse the EGFR pathway to facilitate wound repair itself.” They found that in response tofull-thickness wounding, highly activated Tregsexpand in skin and play a major role in limit-ing production of the key macrophage acti-vator IFN-�, thus minimizing the accumulationof proinflammatory macrophages. In addition,removing Tregs from the wound-healing equation by ablating them early after wound-ing significantly delayed re-epithelializationand the kinetics of wound closure. (see photoon page 9). So Tregs turn out to be criticalplayers in wound healing, limiting wound-as-sociated inflammation on the one hand anddirectly enabling normal wound repair toprogress on the other.

Rosenblum points out that some thera-peutic approaches to treating chronic skin ul-cers have focused on increasing EGFRsignaling. “Our data suggest that these strate-gies may work, in part, by augmenting cuta-neous Treg function,” he reflects. And it may be inadequate or ineffective Tregs that set thestage for chronic ulcers in the first place.Rosenblum believes that “direct therapeuticmanipulation of Tregs may be a novel strategyfor treating wound-associated inflammationwith the potential to expedite healing.”

Regulating the Hair Follicle CycleThe maintenance of tissue homeostasis

is critically dependent on two elements—thecompetence of tissue-resident immune cellsand the differentiation capacity of tissue-resident stem cells (SCs). The hair follicles andTregs are so intimately intertwined that if hairfollicle development is knocked out, Tregs do not migrate into the skin. Because the skinTregs preferentially localize to hair follicles,which house a major subset of skin stem cells(HFSCs), Rosenblum wondered if they partic-ipate in some way in the differentiation of epithelial SCs.



Low hair density represents skin harvested fromhuman anatomical sites with relatively lower hairfollicle density (trunk, upper proximal extremities);high hair density represents skin harvested fromhigher hair density sites (scalp, face). (Reprintedwith permission from J Clin Invest. See SuggestedReadings for citation.)

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Hair follicles are highly specialized organelles that are in a perpetual state ofgrowth and regeneration. A major epithelial SC population localizes to hair follicles (alongwith the Tregs residing there), with dual responsibilities. They are indispensable to hairfollicle regeneration and to repair of the epi-dermal barrier after injury. There were alsosome provocative data links between Tregsand hair follicle biology. Genome-wide associ-ation studies in alopecia areata (AA), a disor-der of hair follicle regeneration, have revealedsingle nucleotide polymorphisms in genes in-volved in Treg differentiation and function.They include IL-2, the high-affinity IL-2 recep-tor alpha, CTLA-4, Eos, and Foxp3. In addition,using low-dose IL-2 for pharmacologic aug-mentation of Tregs in people with AA hadbeen highly efficacious.

“Yet despite all of these associations,”Rosenblum points out, “a functional link be-tween Tregs and hair follicles had yet to be established.” Knowing that Tregs in bone marrow co-localize with hematopoietic SCs—and had been found to support SC functionin this tissue—amplified his curiosity further.

“We began by performing comprehen-sive immune profiling of Tregs in mouse skinat specific stages of the synchronous HFcycle,” Rosenblum says. Looking first at skin-draining lymph nodes, they found that thenumber of Tregs showed little variability innumber. But in the skin itself, accumulationwas not only highly variable, this variance cor-related tightly with HF cycling. Tregs wereroughly 3 times more abundant in the telo-gen phase compared to anagen. After estab-lishing that Tregs play a major role infacilitating hair follicle regeneration by pro-moting the telogen-to-anagen transition,Rosenblum looked more closely at the Tregs’location in the complex geography of the hairfollicle where they reside. He wanted to see ifthey co-localize specifically with HFSCsthemselves. Immunofluorescence micro-scopy enabled him and his team to docu-ment that they cluster around the bulgeregion of the lower portion of telogen hair

follicles (see photoat left), which is awell -establishedniche for HFSCs.Specialized stain-ing revealed a sub-population of bulge-associated Tregs inclose associationwith HFSCs them-selves. And the ma-jority of follicularTregs locate within 0–5 �m of bulgeHFSCs (see graphat left). Using in-travital imaging forreal-time observa-

tion of the behavior of Tregs closest and far-thest from the follicular epithelium providedadditional support. Tregs were highly active inthe bulge region and their potential for com-municating with bulge-associated HFSCs wasapparent. (See photo on cover.) In anotherpiece of the puzzle, lineage-specific depletionof these cells resulted in marked attenuationof hair follicle regeneration. Rosenblum andhis team also discovered that—at least inmice—signaling through the Notch pathwayis a major mechanism by which Tregs pro-mote HFSC function. Rosenblum suspectsthat this relationship between Tregs and HFSCfunction exists in humans but that the rele-vant pathway will turn out to be different.

“Taken together, these results suggest thatsuppression of inflammation is not the majormechanism by which Tregs promote HFSCproliferation and differentiation,” Rosenblumpoints out. “Our data suggest that Tregs in skinhave the ability to modulate the biology of tissue SCs independently of this function,which is a fundamental departure from theway Tregs are thought to work, ie, the tradi-tional view of regulating inflammation. Al-though the overwhelming body of literaturesuggests that this is the sole function of thesecells,” Rosenblum continues, “we and othershave clearly shown that they act in importantways that are independent of their ability tosuppress inflammation. And that is the majorcrux of this area of our research—that regu-lating inflammation is not the central mecha-nism mediating this effect of Tregs on hairfollicles. It is a huge departure in the way thatpeople think about these issues,” Rosenblumconcludes. “We are deviating from doctrine.”

Tregs and Commensal MicrobesOur commensal microbiota are protec-

tive, residing primarily at barrier sites—eg, the gastrointestinal tract, respiratory tract, urogenital tract, and skin—where they func-tionally tune our innate and adaptive immunesystems. Immune tolerance to these residentmicrobes has to be established at each barrier site, and until Rosenblum’s lab began

to study this phenomenon in the skin, research had focused almost exclusively inthe gastrointestinal tract.

Yet the skin is a key barrier site and a richimmunologic organ. Each square centimetercontains over a million lymphocytes and amillion commensal bacteria, pointing to aconstant dialogue between the immune sys-tem and these microbial residents. And as our external body surface, the skin regularlysustains contact with a spectrum of exoge-nous microbes. The skin is also a far morecomplex tissue than the other barrier sites, astratified and cornified epithelium with a diverse topography studded by adnexal struc-tures that include hair follicles, sweat ducts,and sebaceous glands. The maintenance of a healthy immune dialogue with commensalmicrobes is not simple, and recent researchsuggests that disrupting the interactions between Tregs and skin commensals mighthave enduring health implications.

Rosenblum and his team—led by TiffanyC. Scharschmidt, MD, assistant professor in the department who now has her own lab—demonstrated that immune tolerance to com-mensal microbes is established during aprecise period of neonatal life, a crucial window defined by an abrupt influx of highlyactivated Tregs into neonatal skin. And that is when the hair follicles—which are a pri-mary reservoir for skin commensals—beginto poke through the skin and the commensalmicrobes descend. Tregs are recruited at thispoint to establish tolerance to the microbiota.Selective inhibition of this Treg wave com-pletely abolishes commensal tolerance.

Moving on to identify what initiates thiswave of Treg migration into neonatal skin,Rosenblum and his team found that theneonatal hair follicle and commensal mi-crobes interact to increase expression of thechemokine CcI20. The receptor that respondsto CcI20, called Ccr6, is preferentially ex-pressed by Tregs in that early period. This hairfollicle-microbiota teamwork recruits Tregcells into skin, which then function to protectthese commensals from immune recognition.

Treating Autoimmune Disease—It’s All About Balance

“We used to believe that people who de-velop autoimmune disease were unlucky, inthat they had autoreactive immune cells thathad escaped detection in the thymus or pe-riphery and were now wreaking havoc in thetissue,” Rosenblum notes. “But now we thinkthat everybody has such cells. And the reasonthat most people do not go on to develop au-toimmune disease is that their Treg cells arekeeping their autoreactive immune cells incheck.” Autoimmune disease develops whenTreg activity is deficient and this balance is nolonger maintained. This would also explainwhy it is common for patients to have morethan one autoimmune disease.

Tregs cluster around bulge. Left: Immunofluorescence microscopy showsFoxp3+ Tregs (green) clustering around the bulge region (“B”) of a mouse hair folliclein telogen skin. Dashed line outlines the hair follicle. (DAPI is a fluorescent bluestain.) Right: Quantification of fluorescent Foxp3+ Tregs within 30 µm of follicularepithelium shows majority residing within 0–5 µm of bulge HFSCs. ***p<0.001.(Reprinted with permission from Cell. See Suggested Readings for citation.)

HF Treg distance to HFSC (μm)

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This new understanding dramatically redefines—and simplifies—the therapeutictarget. It will no longer be eliminating the specific population of autoreactive immunecells for an individual autoimmune disease.Instead the goal will simply to augment theTreg population and restore the body’s natu-ral ability to regulate this. It is truly a one-size-fits-all treatment for autoimmune disease,because it is approaching the basic cause, nota symptom of that cause. Giving a pharmaco-logical agent that augments the immune regulatory presence to dampen the patho-logic effector response will reset the balanceof the immune system. “I believe that this isthe future of treating autoimmune diseases,”Rosenblum states.

Final Thoughts“One of the biggest surprises we have

had so far is how many diverse functions Tregshave in the skin,” Rosenblum emphasizes. “The skin is home to a large portion of thebody’s Tregs, which speaks to the fact thatthese cells are definitely a major player in thistissue. And we are beginning to understandthat they have a diverse array of functionswithin this tissue, related to context. Tradition-ally we think of these cells as defined withinthe narrow perspective of conventional im-mune responses. But in the tissue, they dothat—and so much more! And it’s the ‘somuch more’ that’s been really surprising.”

Rosenblum continues to probe this “somuch more.” He has been looking moreclosely at the contribution of skin-residentTregs to the maintenance of barrier functionand the restoration of barrier tissue integrityafter injury, and a possible interaction with fi-broblast function that may have implicationsfor understanding and treating fibrotic skindisease. Stay tuned.

Suggested ReadingsAli N, Rosenblum MD. “Regulatory T cells

in skin.” Immunol. 2017;152:372–81.Rosenblum MD, Way SS, Abbas AK. “Regu-

latory T cell memory.” Nat Rev Immunol.2016;16:90–101.

Rodriguez RS, Pauli ML, Heuhaus IM, YuSS, et al. “Memory regulatory T cells reside inhuman skin.” J Clin Invest. 2014;124:1027–36.

Nosbaum A, Prevel N, Truong HA, Mehta P,et al. “Cutting Edge: Regulatory T cells facili-tate cutaneous wound healing.” J Immunol.2016;196:2010–4.

Ali N, Zirak B, Rodriguez RS, Pauli ML, et al. “Regulatory T cell in skin facilitate epithelial stem cell differentiation.” Cell.2017;169:119–29.

Scharschmidt TC, Vasquez KS, Truong HA, Gearty SV, et al. “A wave of regulatory T cells into neonatal skin mediates toleranceto commensal microbes.” Immunity. 2015;43:1011–21. �


Dr. Rosenblum received funding from theDermatology Foundation: 2009 InvestigatorResearch Fellowship; 2010 Career Develop-ment Award; 2015 Stiefel Scholar Award.

Annenberg Circle Welcomes Newest Members

The DF Board of Trustees extends deep gratitude to thosewho have pledged $25,000 in 2017 to meet the criticalneed for funding the research progress that is essential for advancing patient care. They join more than 600 colleaguesin making this valuable investment in the future.

David H. Chu, MD, PhDBeth A. Drolet, MDCraig J. Eichler, MDRichard F. Eisen, MD

Brad P. Glick, DO, MPHAnn E. Hern, MDSylvia Hsu, MD

Sarah C. Jackson, MDCarrie L. Kovarik, MD

Oanh Lauring, MDSancy A. Leachman, MD, PhDFrederick A. Lupton, III, MD

Susan L. Malane, DOThuy Vi Nguyen, MD

Sharon S. Raimer, MDFaramarz H. Samie, MDJorge L. Sanchez, MD

Alan K. Silverman, MDTravis W. Vandergriff, MD

Paula S. Vogel, MD

Tregs and wound healing. Histology at 7 days afterwounding compares the rapid healing of wild-typemice (WT) with the slow healing of mice whose Tregs were silenced after wounding (DTR Early).Arrowheads denote wound edges. (Reprinted withpermission from J Immunol. Copyright 2016. TheAmerican Association of Immunologists, Inc. SeeSuggested Readings for citation.)


ALABAMAChairRuth A. Yates, MDVice ChairMelanie L. Appell, MD*Gregory Bourgeois, MD

ARKANSASChairHenry K. Wong, MD, PhD

ARIZONAChairLindsay Ackerman, MDVice ChairAaron Mangold, MD

CALIFORNIA–LOS ANGELESChairJashin Wu, MD

CALIFORNIA–SAN DIEGOChairNeal D. Bhatia, MD

CALIFORNIA–BAY AREAChairEric S. Fromer, MDVice ChairAdrianna Browne, MD*Anna K. Haemel, MDRoberto R. Ricardo-Gonzalez,

MD, PhDTiffany C. Scharschmidt, MD

CALIFORNIA–SACRAMENTOChairAn Yen, MD

COLORADO ChairRobert P. Dellavalle, MD, PhD*Vice ChairCory A. Dunnick, MDPeggy B. Liao, MDKelly Morrissey Williams, MD

CONNECTICUTChairOscar R. Colegio, MD, PhDVice ChairChristopher G. Bunick, MD, PhDAmanda Zubek, MD, PhD

DISTRICT OF COLUMBIA–BELTWAYChairWilliam S. Sawchuk, MD

GEORGIAChairTravis Blalock, MDVice ChairMisty D. Caudell, MD

IOWAChairKent D. Walker, MDVice ChairJoshua Wilson, MDJohn H. Wollner, MD

IDAHOChairRyan S. Owsley, MD

INDIANA ChairNorma H. Schmitz, MDVice ChairSally A. Booth, MDGinat W. Mirowski, DMD, MD

LOUISIANAChairAmie Shannon, MDVice ChairKim Bui Drew, MDStephen Klinger, MDFrankie G. Rholdon, MD

MARYLAND–BALTIMORE ChairSaif U. Syed, MDVice ChairJennifer Z. Cooper, MDDiane S. Ford, MDZain U. Syed, MD

MICHIGANChairDana L. Sachs, MD*Vice ChairMichael T. Goldfarb, MD

MISSOURIChairNicole Burkemper, MDVice ChairTricia Missall, MD, PhD

NORTH CAROLINAChairWilliam W. Huang, MD, MPHVice ChairAdela Rambi G. Cardones, MDDonna A. Culton, MD, PhDGloria F. Graham, MD

NEW JERSEY–NORTHChairAdrian L. Connolly, MD

NEW JERSEY–SOUTHChairWarren R. Heymann, MD

NEVADA ChairVictoria G. Farley, MD

NEW YORK–DOWNSTATEChairKishwer S. Nehal, MDVice ChairSherri K. Kaplan, MDShari Lipner, MD, PhDAnthony M. Rossi, MDJennifer A. Stein, MD

NEW YORK–UPSTATEChairSherrif Ibrahim, MD, PhD

OHIO–SOUTHChairShannon Campbell Trotter, DO

OHIO–NORTHChairJonathan Bass, MDVice ChairJaye E. Benjamin, MDMichael L. Cairns, MDNeil J. Korman, MD, PhD*Stephen C. Somach, MD

PENNSYLVANIA–WESTChairRenee J. Mathur, MD

PENNSYLVANIA–EASTChairCarrie Ann R. Cusack, MDVice ChairEmily Y. Chu, MD, PhD

RHODE ISLANDChairLeslie Robinson-Bostom, MD

SOUTH CAROLINAChairJohn C. Maize, Jr., MD

TENNESSEEVice ChairVineet Mishra, MD

TEXAS–DALLASChairRebecca L. Euwer, MD

Vice ChairSeemal Desai, MDRobin A. Roberts, MD

TEXAS–SANANTONIO/AUSTINChairAllison J. Stocker, MDVice ChairJohn Browning, MDThomas L. Davis, MDCatherine L. Kowalewski, DOKeagan H. Lee, MDVineet Mishra, MD

TEXAS–WESTVice ChairVineet Mishra, MD

TEXAS–EAST Vice ChairVineet Mishra, MD

UTAHChairJacqueline Panko, MD

WASHINGTONChairJennifer M. Gardner, MDVice ChairCampbell Stewart, MD

WISCONSINChairKathleen S. Stokes, MD*Vice ChairJulia Kasprzak, MDYaohui Gloria Xu, MD, PhD

WEST VIRGINIAChairStuart R. Lessin, MD

Dermatologic Surgery CampaignChairElizabeth I. McBurney, MDVice ChairM. Laurin Council, MDMary E. Maloney, MD

Dermatopathology CampaignChairJohn T. Seykora, MD, PhDVice ChairJ. Andrew Carlson, MDMaxwell A. Fung, MDLeslie Robinson-Bostom, MDCurtis T. Thompson, MD

*Enrolled three or more new (paid)LS members

“Thank You” to Leaders Society VolunteersThe DF Board of Trustees extends the deepest appreciation to every one of the national campaign volunteers listed here. They have worked to increase leadership giving in their area. Their concern for continued progress in patient care, and their gift of time and effort throughout the year, helped to expand support for advancement in the specialty.

handling or culture, and they stimulate a vari-ety of helpful growth and healing pathwayswithout raising the risk of cancer or initiatinga significant immune response.

Thus autologous adipose tissue has become the go-to approach for a disparate variety of problems, a number of which arealso commonly treated by dermatologic sur-geons. Percec relies on it for restoring facialvolume lost with aging, and for treating soft tissue volume loss acquired through traumaor congenital malformation. She uses it foraugmenting the buttocks and breasts, forrestoring breasts after lumpectomy, and for reconstructing them after mastectomy. Sheuses autologous fat to normalize fibrotic skinafter radiation damage. She relies on it to helpsluggish wounds heal. And it is critical for female genital reconstruction after ritual mutilation. But that is only part of the story.

Critical Questions Remain Unanswered

The type of research needed to supportoptimal use of autologous fat grafts has notkept pace, which has generated Percec’s deepconcern. She understands that the true potential of autologous fat grafting cannot beadequately recognized or accessed until thisresearch is done—and done properly.

On the one hand, there are no reliablemethodologic guidelines for maximizing theprobability of a successful outcome. “We donot know how to harvest the tissue or injectthe lipoaspirate properly, or optimize our results—so only about 40–60% of what we inject remains,” she says. Disagreement con-tinues even on the most effective tools to usethroughout the process.

And there are critical unanswered ques-tions on the role of ASCs in successful graftsurvival, despite the recognition that humanadipose tissue is the ideal mesenchymal stemcell source for the adult stem cell-based ther-apies that have become a primary focus in regenerative medicine. The appeal of ASCs reflects their compelling profile (see box onpage 12), including their outstanding multi-potentiality. Roughly 130 active clinical trialsare listed by the NIH. Yet the mechanisms regulating these cells before and after harvest,as well as their behavior after in vivo trans-plantation—differentiation, migration, andcell survival—remain to be identified and un-derstood. And the basic issues of ASC preser-vation have yet to be assessed. This range ofconcerns regarding the current use of autolo-gous fat grafts and the hoped-for benefits ofASCs is shared by dermatologists involved inaesthetic and reconstructive surgery.

Goals This is the territory that Percec is explor-

ing in her lab, using human adipose tissue andworking at the molecular level. She believes it is crucial to move away from in vitro prepa-rations and animal models and focus onhuman cells, because roughly 90% of the dis-coveries made in mice or other animal mod-els do not translate to humans. Although thegenetic heterogeneity among people makeshuman cells more difficult to work with thancells from a controlled animal populationwith a single genetic makeup, Percec knewthat the direct relevance of data would beworth the challenge, and deriving stem cellsdirectly from her patients would give her com-plete control over all of the clinical variablesand storage aspects. After working out the antecedents, she has launched her pursuit ofthe complex regulatory mechanisms control-ling adipose tissue and ASC biology—in vivo,in storage, and after transplant—to identify themolecular pathways that will optimize thefunction of these stem cells.

Adipose Stem Cells—A Model for Soft Tissue Aging

A primary goal of Percec’s has been touse these stem cells as a relevant model forhuman soft tissue aging that would allow herto study the process and evaluate potential in-terventions. The mechanisms responsible forsoft tissue aging are becoming progressivelymore important as the world’s populationages, yet most studies on aging have been conducted either in animal models—typicallymice—or with an artificial model such ascells cultured from progeria patients, or cellsin the culture flask forced to replicate tosenescence. Because none of these repre-sents normal human aging, clearly relevantmolecular pathways and alterationshad yet to be identified. Percec wasconvinced that human adipose tis-sue from healthy individuals cangenerate this knowledge, and thatwhat she would learn as she studiedthem should ultimately also help tounderstand—and hopefully im-prove—the clinical experience withautologous fat grafting. Advanced patient age reduces graft success aswell as ASC quantity and viability; fat from different anatomic compart-ments may age differently; fat frommen and women may have signifi-cant aging differences.

To prepare for this study, Percecconceived of a preservative-free

method for freezing freshly harvested adiposetissue. The absence of preservatives enablesher to maintain the stem cells as close to theirnatural state as possible and avoid distortingor impairing their function. After perfectingthe approach, then building her tissue bank,Percec looked for differences in genomic tran-scriptional profiling—ie, RNA profiles that indicate the individual pattern of gene ex-pression—between the primary cell types inadipose tissue, and between youthful andolder age groups.

Percec studied subcutaneous adipose tissue that she had excised from the anteriorabdomen of 6 healthy patients—3 young (26–29 years) and 3 older (52–64 years)—during cosmetic procedures. She isolatedadipocytes and stromal vascular fractions forgenome-wide transcriptional analysis, lookingfor gene expression differences between celltypes and between age groups. She foundthem. Age showed an increase in overall gene expression among older patients but,very unexpectedly, these differences were ex-tremely modest. Pronounced differences wereidentified between cell types. Age-related differences were a very distant second. (Seebar graph below.)

Long-Term Storage and Age: Exploring the Impact

Thinking ahead to potential future ac-ceptance of ASCs in regenerative applications,Percec knew that “advancing patient age wasbelieved to correlate with impaired ASC differentiation and growth profiles.” The implication was that for the large majority ofpatients, by the time emerging health issuesrequire regenerative treatment, a patient’sfreshly harvested ASCs would no longer be functioning optimally. Perec’s envisioned

Focus on ResearchAdipose Stem Cells—Understanding Them and Their Potential Value

for Aesthetic and Regenerative Medicine(Continued from cover)


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Microarray analysis to identify differentially expressed genes pro-filed freshly harvested adipocytes and stromal vascular fractioncomponents from 3 young (26–39 years) and 3 old (52–64 years)healthy patients. Cell type was the most significant contributionto transcriptional variation; age was a distant second. (Reprintedwith permission from Ann Plastic Surg. See Suggested Readingsfor citation.)


solution is a standard practice of banking sub-cutaneous adipose tissue while a person isyoung and healthy, then years later—if andwhen needed—retrieving their cryopreservedtissue to isolate and use stem cells. Contrary

to the approach for creating stem cell reservesfrom umbilical cord blood—isolating, ex-panding, and storing only the stem cells—Percec believes in storing the entire tissue tokeep the stem cells within their nourishing

and protective niche until they are needed.With this in mind, she looked at the effect ofcryopreservation length and patient age onASCs freshly harvested from cryopreservedadipose tissue.

She and her team used tissue from patients 26–62 years old that was excised during abdominoplasties and then cryopre-served from 2–1,159 days (slightly >3 years).ASC number and viability were assessed atthe initial excision, then measured post-harvest—along with rate of growth—after 9,18, and 28 days of growth.

Although significantly more viable cellswere initially isolated from tissue cryopre-served for less than 1 year compared to cryo-preservation beyond 2 years, this differencedisappeared as the growth phase continued.There were no significant differences in stemcell viability or growth rate at subsequent timepoints regardless of cryopreservation durationor patient age. So although longer cryopreser-vation negatively affects the initial live ASC iso-lation results, this effect is neutralized as thegrowth phase continues. As for the effect ofpatient age, comparing cells from patients <40 years with patients ≥50 showed no signif-icant differences in initial ASC viability or ingrowth after cryopreservation (see graph onpage 14). Mesenchymal stem cell markerswere maintained in all age cohorts through-out the study’s duration (see graphs at left).And ASCs from all subgroups were equally capable of undergoing both osteogenic andadipogenetic differentiation.

Percec and her team were so unpreparedfor the capacity of these adipose-derived stemcells to preserve their youthfulness “that it tookseveral years for us to accept these findingsand stop wondering if our models were not ad-equate or we were not including a sufficientnumber of patients,” she comments. “But it be-came clear that the older stem cells could notonly be harvested after years of being stored,they could replicate almost as well as youngerstem cells. They maintain their stability—although we do not yet fully understand how.”

The maximum duration of cryopreserva-tion is currently 7 years now, and harvestingthe original samples continues to produce re-liably effective stem cells. “This study providesevidence that whole adipose tissue cryo-preservation can serve as the gold standardfor long-term ASC biobanking,” Percec says.“Taken together, our data suggest that ASCspreserved within their tissue niche are cap-able of enduring long-term cryopreservationwhile maintaining their stemness. Whole-tissue cryopreservation avoids any potentialadverse effects caused by cellular trauma orby the use of cryopreservative media,” shepoints out. “Because of the incremental decrease in subcutaneous adipose tissuemass with advancing patient age,” Percec

The Biology and Benefits of Subcutaneous Adipose Tissue

Human fat—a mesenchymal tissue and the largest contributor by volume tothe connective tissue matrix—is composed of matrices of adipocytes inter-spersed with collagen fibers and the stromal vascular fraction (SVF). The SVF includes preadipocytes (adipose precursor cells), adipose stem cells (ASCs), fibroblasts, pericytes, vascular endothelial cells, and immune cells (tissuemacrophages, B cells, and T cells). The first hint that human adipose tissue isnot simply an inert filler that stores lipids, cushions our organs, and helps to keepus warm came just over 20 years ago. In 1994, the first adipokine—a cytokine secreted by adipose tissue—was discovered, with hundreds more to follow. As recently as 2010, scientists identified an additional 20 proteins not previously detected in human fat cells, and 6 novel proteins never seen before.

Adipose tissue is collectively the body’s largest endocrine organ, with an exceedingly complex and varied profile. It produces and releases a vast array ofprotein signals that include growth factors, cytokines (including TNF and IL-6),chemokines, acute-phase proteins (which increase or decrease in response to inflammation), complement-like factors, adhesion molecules, components of theextracellular matrix, and hormones. These trophic factors substantially enhanceASC impact. Changes in adipose tissue function can be triggered by either plasmamembrane receptors (for insulin, glucagon, growth hormone, adiponectin, gas-trin, and angiotensin-II) or nuclear receptors (for PPAR , estrogens, androgens,vitamin D, thyroid hormone, progesterone, and glucocorticoids). Thus adiposetissue is vital to metabolic homeostasis, immune regulation, angiogenesis andcoagulation, and contributes significantly to regulating reproduction, fibrinolysis,vascular tone control, and body weight homeostasis. It is also a factor inlongevity.

Of special significance is that subcutaneous adipose fat—85% of all adiposetissue in the human body—is the largest known reservoir of adult stem cells, potentially the most abundant source of regenerative cells in the human body.Their immunogenicity is very low, and ASCs can differentiate into a substantialrange of cell types including osteocytes, adipocytes, neural cells, vascular endothelial cells, cardiomyocytes, pancreatic cells, and hepatocytes. ASCs’ strongparacrine signaling mechanisms confer multiple protective effects. They are anti-inflammatory, proangiogenic, immunohomeostatic, protect against neurodegen-eration and cancer, and promote scarless wound healing. Their secretion ofcytokines, chemokines, and growth factors stimulates the body’s innate regen-erative capacity in a wide range of applications, and the trophic factors expressedby the tissue enhance this.

CD

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Sorting ASCs by flow cytometry to characterize the molecular marker profile for cells from adipose tissue harvested from patients of different ages and after different cryopreservation durations showed the retentionof both stemness and proliferative ability in the great majority of stem cells from each source. (Reprinted withpermission from Stem Cells Int. See Suggested Readings for the citation.)



ALABAMAJohn Anthony, MDKathleen Beckum, MDGregory Bourgeois, MDAnne H. Bussian, MDCharles Parrish, MDAlexander Wong, MD

ARIZONAMiriam P. Cummings, MDMark V. Dahl, MDDaniel P. Skinner, MD

CALIFORNIAGlynis R. Ablon, MDSusan Amaturo, MDErin H. Amerson, MDApril W. Armstrong, MD, MPHRon A. Birnbaum, MDBarbara A. Burrall, MDInder P.S. Dhillon, MDJennifer Fu, MDEdward Glassberg, MDLori M. Hobbs, MDRenee M. Howard, MDBryna Kane, MDMaija Kiuru, MD, PhDKhosrow M. Mehrany, MDMartin Brier Miller, MDAlan A. Semion, MDJane S. Wada, MD

COLORADOMayumi Fujita, MD, PhDRenata P. Oliveira, MDAlexandra Theriault, MD

DISTRICT OF COLUMBIAAlicia D. Braun, MDMarisa A. Braun, MD

DELAWAREKathryn E. O’Reilly, MD, PhD

FLORIDAKenneth R. Beer, MDMichael E. Berman, MDStephanie A. Caradonna, MDConor P. Dolehide, MDMatt L. Leavitt, DO

GEORGIAJohn T. Apgar, MDVirginia Rutledge Forney, MDBillie L. Jackson, MDJay A. Levin, MD

ILLINOISErin K. Burns, MDLester J. Fahrner, MDStephanie Frisch, MD

INDIANAA. David Gerstein, MDJohn K. Randall, RPh, MD

LOUISIANABarbara S. Bopp, MDJohn Chapman, MDRachel Dean, MDKeith G. LeBlanc, Jr., MDDana A. Marshall, MDJan B. Wampold, MD

MASSACHUSETTSRhoda Myra Alani, MDMark A. Blumberg, MDThomas H. Cahn, MDTeresa M. DeGiacomo, MDJennifer T. Huang, MDClaire P. Mansur, MDAbena Ofori, MDEmily Stamell Ruiz, MDAndrew D. Samel, MDHensin Tsao, MD, PhD

MARYLANDNicola S. Bravo, MDEdward Cowen, MDPaul A. Rusonis, MDZain U. Syed, MD

MICHIGANJenny Cotton, MD, PhDKaren A. Heidelberg, MDMichelle S. Legacy, DOJudith T. Lipinski, MDJoan M. Rindler, MD

MINNESOTAAnne Neeley, MDElyse Scheuer, MDGabriel F. Sciallis, MD

NORTH CAROLINARussell A. Ball, MD

NEW JERSEYKaren Connolly, MD

NEW MEXICOPhillip James Eichhorn, MD

NEW YORKJesleen Ahluwalia, MDAlisa N. Femia, MDElizabeth K. Hale, MDArielle N.B. Kauvar, MDFrancisco Ramirez-Valle, MD, PhDGeorge Varghese, MD

OHIOValerie Fuller, DOCurtis W. Hawkins, MDAri Konheim, MDWilliam V. Krug, MDPatrick L. Shannon, MDSteven J. Taub, MDShannon Campbell Trotter, DO

OREGONTeri Greiling, MD, PhDJessica A. Spies, MD

PENNSYLVANIACynthia Bartus, MDAmy L. Basile, DOJeremy R. Etzkorn, MDLouis D. Falo, Jr., MD, PhDScott L. Gottlieb, MDPaul L. Haun, MDSharon L. Hrabovsky, MDEllen J. Kim, MDJoslyn S. Kirby, MDScott J.M. Lim, DOCory L. Simpson, MD, PhD

SOUTH CAROLINA

Robert D. Bibb, MDTodd Schlesinger, MD

TEXAS

Sulochana Bhandarkar, MDChris W. Crawford, MDLucia Diaz, MDBethany Grubb, MPAS, PA-CTamia Harris-Tryon, MD, PhDLindsey D. Hicks, MDLeisa Hodges, DOMark F. Naylor, MDAllison B. Friss Singer, MDAmanda Wolthoff, MD

UTAH

Michael W. Peterson, DORichard D. Sontheimer, MD

VIRGINIA

Laura L.K. Pratt, MD

VERMONT

Christine Haughey-Weinberger, MD

WASHINGTON

Philip Fleckman, MDMichi Shinohara, MDMark Conrad Valentine, MD

WISCONSIN

Lisa M. Arkin, MDJ. Christopher Braker, MDJulia Kasprzak, MDLinda H. Lee, MD, PhDDawn H. Siegel, MDAndy Swanson, MD

Italics = Young Leader (5 years or lessout of residency)

New 2017 Leaders Society Members Invest in Progress The Foundation welcomes the forward-looking dermatologists who chose to join their colleaguesin the Leaders Society, and appreciates their confidence in the DF’s ability to identify and support tomorrow’s leaders driving progress in the specialty. Their wise decision to invest$1,500 annually in this effort will translate to advancing patient care for years to come.

continues, “it behooves us, when feasible, tobank this valuable tissue prior to its diminu-tion, ideally by middle age.”

Digging Deeper To begin exploring what underlies the

human ASC’s remarkable stability during theprogression to early aging, Percec and herteam decided to compare ASCs from healthywomen between ages 24–64 with two othercell populations. One comprised freshly har-vested age-matched dermal fibroblasts. Theother—a common model of cellular agingcalled IMR-90—is a human fetal lung fibro-blast pushed to senescence by forcing an ex-tensive number of cell doublings. Percecdivided the stem cell and fibroblast popula-tions into younger and older subgroups, thenassayed the transcriptome of each subgroupand the IMR-90 cells. This basically producedan RNA map for each group showing thegenes being actively transcribed, and eachgene’s relative share of the RNA pool. Percecand her team were looking for genes associ-ated with age-related regulation that departedsignificantly from the youthful pattern with amore than twofold increase or decrease in expression.

The differences were clear and dramatic.Age-related gene expression changes wereminimal in the ASCs, compared to dramaticage-related changes in the other two cellgroups. In early-aging ASCs, only 279 geneswere strongly upregulated and 95 were down-regulated. But these numbers were far greaterin aging fibroblasts and senescent IMR-90cells—1,180 and 857, and 660 and 1,778, respectively. The effect of the altered gene expression in aging ASCs basically speeds upgene translation and the cell cycle. Just the opposite occurs in the other two cell groups,where these processes slow down considerably.“These synergistic modifications suggest thatmultiple regulatory events at the transcrip-tional, translational, and post-translational levels act together to enable aging ASCs tomaintain their ‘stemness’ and tissue homeo-stasis,” Percec explains. “Our results revealnovel chronological aging mechanisms inASCs that are inherently different from differ-entiated cells,” she continues, “and that may reflect an organismal attempt to meet the in-creased demands of tissue and organ homeo-stasis during aging.” These robust cells do thework needed to retain stable youthful function.

In ProgressThe SIRT1 enzyme is critical to cellular

health and longevity. Percec is assessing itsrole in healthy ASC function, and possible de-ficiency in impaired ASCs—eg, from aged orobese patients—that can no longer producesufficient adipocytes and are typical of de-fective autologous grafts. She will also see ifdeficient status can be reversed. A relatedissue is the role of mitochondrial activity inhealthy SIRT1 function, which Percec is alsoexploring in the context of healthy vs defec-tive ASCs. Again, pharmacological reversal ofany identified mitochondrial deficiency willbe attempted. Yet another focus targets the po-tential for improved wound healing. Percecwill induce ASCs from healthy female patients

(ages 25–59 years) to differentiate into fibroblasts, and their ability to produce extra-cellular matrix and generate rapid healingwith less scarring will be compared to dermalfibroblasts harvested from these same pa-tients. In another vein, Percec is intrigued with the juxtaposition of normally mutuallyexclusive characteristics in ASCs. On the onehand these stem cells are exceptionally qui-escent, which protects them from the onco-genic potential that is a disadvantage of somany other stem cells. But these same stemcells also show remarkable regenerative capacity. “This is one of the puzzles we are trying to decipher,” Percec says. And last butnot least, they are going to evaluate the ASCsfrom an obese population to see if they responddifferently to aging and to cryopreservation.

Thoughts About the FuturePercec covers both ends of the time spec-

trum when she comments about her hopesfor progress in using adipose tissue and ASCstherapeutically. Concerning the current clini-cal applications of autologous fat grafts, “weare still so far behind in developing the idealmethodology for treating fat properly and allowing it to have a much more robust andpredictable viability once it is transferred,” shecautions. And thus Percec looks forward to theresearch that is urgently needed to establishthe most effective methodology. And lookingto the future, Percec points out that ASCs haveeven shown therapeutic benefit in animalmodels of cardiac ischemia or stroke. “Andwhen they are injected directly into the animal’s bloodstream, they actually target theinjured tissue,” she points out. “Can this be ourgoal down the line? It would be amazing!”

Suggested ReadingsHsu VM, Stransky CA, Bucky LP, Percec I.

“Fat grafting’s past, present., and future: whyadipose tissue is emerging as a critical link tothe advancement of regenerative medicine.”Aesth Surg J. 2012;32:892–9.

Stransky CA, Hsu VM, Dierov R, HooverWJ, et al. “Beyond fat grafting: what adipose tissue can teach us about the molecularmechanisms of human aging.” Ann PlasticSurg. 2012;69:489–92.

Devitt SM, Carter CM, Dierov R, Weiss S, etal. “Successful isolation of viable adipose-derived stem cells from human adipose tissue subject to long-term cryopreservation:positive implications for adult stem cell-basedtherapeutics in patients of advanced age.” StemCells Int. 2015;2015:doi: 10.1155/2015/146421.

Shan X, Roberts C, Kim EJ, Brenner A, et al.“Transcriptional and cell cycle alterationsmark aging of primary human adipose-derivedstem cells.” Stem Cells. 2017;35:1392–1401.

Gersch RP, Glahn J, Tecce MG, Wilson AJ, et al. “Platelet rich plasma augments adi-pose-derived stem cell growth and differenti-ation.” Aesth Surg J. 2017;37:723–9. �


A Timeline of Firsts 1893: The German plastic surgeon Gustav Neuber discussed his novel approach—autologous fat grafting—to filling a soft tissue facial defect (a large conical infraorbital scar from childhood tuberculous osteitis) in a young male patient,and satisfying cosmetic outcome. 1895: The first breast reconstruction took place, by transferring a lipoma fromthe patient’s buttock. 1910: The first report appeared of fat injection by a plastic surgeon. 1920: The first book appeared devoted completely to fat grafting. 1950: The first studies appeared on the biology of fat graft survival. 1980: Liposuction was developed, greatly facilitating fat harvest. 1987: The first experiences appeared using liposuctioned fat for breast augmen-tation, but issues in demonstrating efficacy and safety delayed approval by theAmerican Society of Plastic Surgeons for almost 20 years. 2001: Stem cells were identified in human adipose tissue at UCLA’s Laboratory forRegenerative Engineering and Repair.2007: The first report appeared on the benefit of fat grafting for treating radiation-induced tissue damage.

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N=12 N=20<40 <50≥40 ≥50

N=9N=23

ASC viability was compared between the followingage cohorts: <40 vs ≥40, <50 vs ≥50, and <40 vs ≥50.No significant differences were observed. (Reprintedwith permission from Stem Cells Int. See SuggestedReadings for the citation.)


2017 Corporate Honor SocietyPartners in Shaping Dermatology’s Future

The Dermatology Foundation is grateful to the following corporations for their generous contributions last year. Their support furthers the

DF’s mission to develop and retain tomorrow’s leaders in the specialty, enabling advancements in patient care.

Platinum Benefactors ($200,000 or more)

Gold Benefactor ($100,000 or more)

Novartis

Silver Benefactor ($50,000 or more)

AbbVie Amgen Inc.

Lilly USA, LLC Sun Dermatology

ADDRESS SERVICE REQUESTED

Dermatology Focusc/o Dermatology Foundation1560 Sherman Avenue Evanston, Illinois 60201-4806

Non-ProfitU.S. Postage

PAIDPermit No. 236 Melrose Park, IL

Dermatology has matured into an important specialty within the house of medicine. Continuedprogress is enabled by dedicated volunteers like Dr. Elizabeth McBurney, helping the DF increase itssupport of the work that will drive advancements in patient care. Adding to a devoted volunteer history that began in 2000, Dr. McBurney has just taken on the role of Chair of the Annenberg CircleCommittee from departing Chair, James O. Ertle, MD.

Dr. McBurney is highly enthusiasticabout this new opportunity to help thespecialty by bringing her talents to growing AC membership. “The DF isabsolutely critical to the specialty,”she points out. “It was designed bydermatologists, for dermatologists,specifically to help develop advance knowledgeand patient care. AC contributions enable theFoundation—and the essential support it provides—to continue long into the future.”

Dr. McBurney is clinical professor of dermatologyat both Louisiana State University School of Medicine

and Tulane University School of Medicine in New Orleans, and is especially interested in T-cell lymphoma, laser surgery, and skin rejuvenation. She became a Leaders Society member in 1992, and since then has significantly increased her support

of the DF as a member and a volunteer,including service as Secretary-Treasurer.

Dr. McBurney worked with Dr. Ertleas vice chair of the AC Committee since his chairmanship began in 2013. “He has given so unselfishly to the DF of his time and dollars over the years,” Dr. McBurney notes. “His unflagging enthusiasm for the Foundation servesas a beacon for the rest of us. If I am as successful as he was, I will be verygrateful,” she adds.

Dr. McBurney is extremely pleasedto welcome Kishwer S. Nehal, MD, to the committeeas vice chair. Dr. Nehal is director of Mohs and Dermatologic Surgery at Memorial Sloan-KetteringCancer Center in NYC. “With her boundless and infectious energy, she will be a real asset to the committee,” Dr. McBurney says.

“The DF is critical to the future of dermatology.”Giving Back—The New Chair of the Annenberg Circle Committee

The DF is exceptionally grateful to its many volunteers who give so generously of their time to keep dermatology at the forefront of medicine.

Elizabeth I. McBurney, MD

VOL. 36 NO. 4 WINTER 2017/18

A DERMATOLOGY FOUNDATION PUBLICATIONSPONSORED BY ORTHO DERMATOLOGICS

A Division of Valeant Pharmaceuticals North America LLC

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VOL.36 NO. 4 WINTER 2017/18 A Division of Valeant ...world-renowned UCSF immunologist Abul K. Abbas, MD) that launched his groundbreaking series of discoveries, he took a less well-traveled