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2011-08-11
1
New Frontiers and Future Technologies:
Biomaterials, Stem Cells and Tissue Engineering
W. John Kao PhD
Professor of Biomedical Engineering, Pharmacy, and Surgery
University of Wisconsin – Madison
John.Kao.Lab
New Frontiers (challenges) and Future Technologies:
Biomaterials, Stem Cells and Tissue Engineering
Acknowledgments: those who kept us going!
My Students:K Kleinbeck, H Waldeck, Y Fu, C Drifka, K Xu, D Cantu, J Li, A Chung, D Schmidt, S Zuckerman, H Yang, Y Gao, J Phillips, J Meyers, E Joyce, W Johnson, H Cohen
Physician Collaborators: J Niezgoda, L Faucher, M Schurr, P Hematti, H Summer, J Farinas
Basic Science Collaborators:L Allen-Hoffman, G Kwon
Wisconsin Alumni Research Association (WARF): L Cagan, J Burmania, C Gunbrandson
Funding AgenciesNIH, NSF, UWF, UW BME, UW Surgery, UW Pharmacy, WARF, MatriLab
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Outline for this talk
Introduction to clinical challenges
Advanced wound healing therapy: basic research
> Biomaterial-enabled tissue engineering strategies
> Cell-based therapy + HBO2T strategies
What’s next? Going beyond basic research in academia
Introduction to Clinical Challenges
Clinical needs:acute and chronic cutaneous wound healing
Cost of trauma-related deaths in US is 2.4X higher than cancer and cardiovascular diseases combined. *
By 2020, trauma will equal or surpass communicable diseases as the number one cause of disability-adjusted life years worldwide. *
Greater than 50% of wounds remain refractory to current conventional treatment. *
Outcome of acute and chronic cutaneous wound healing can’t be reliably predicted.
* http://www.cdc.gov/ncipc/wisqars/
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The choice of treatment and the development of novel therapeutics depend on the underlying biology and co-morbidity.
Current understanding of many cellular and molecular processes has advanced substantially.
However, efficacy of biomolecules as single agent therapeutics is disappointing.
Complex biochemical pathway
Dynamic wound healing cascade
Underlying pathology
Challenges
Challenges: complex biochemical pathways
Altered genes (+ 5000) in a neutrophil when exposed to LPS
from Calvano SE et al. A netowrk based analysis of systemic inflammation in human, Nature. 2005; 437, 13, 1032.
Challenges: dynamic wound healing cascade
Hemostasis: fibrin clot, platelet aggregation
Inflammation: exudation, phagocytosis, cytokine/growth factor release
Granulation/proliferation: fibroblast/endothelial cells, angiogenesis, provisional matrix formation, wound contracture
Time
Remodeling / Re-epithelialization:Resorption of type III collagen,Type I collagen formation and fiber orientation, keratinocyte proliferation and epithelialization
Chronic or impaired wounds result when tissues fail to progress through
these stages of healing !!
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Advanced Wound Healing Therapy
Biomaterial-enabled tissue engineering strategies:biomimetic biomaterials
New therapeutic paradigm:using biomaterials and therapeutic cells to recapitulate the lost tissue structure and to address underlying disease to improve healing.
Adapted from Clark et al.J Invest Derm 2007
Ideal biomaterial properties
Well-characterized
Biocompatible, safe and effective:
Adheres to tissue and conforms to complex contour
Maintains moist healing environment
Functionalizable to promote healing and patient care
IP protected
Cost effective to synthesize and manufacture
Easily adaptable to current clinical practice
Easy patient compliance
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Examples of clinical biomaterial-based treatment (for granulation wounds)
foams, hydrogels, transparent films, hydrocolloidsprovide a moist environment, some insulation
Allevyn®, Curafoam®, Curasol Gel®, Biolex Wound Gel®,
Bioclusive®, Tegaderm®, DuoDerm®, Replicare®
Adjunctive Therapies: NPT, acellularized tissue graftsVAC®, Oasis®
Although all meets some aspects of “ideal” biomaterials,there remains room for improvementproduct differentiation
labor-intensive patient care
needs to address co-morbidity and underlying pathology
unclear mechanism theory: why and how it works
ScaffoldsPEGdA-PEGSH :chemically modified gelatin
To study cell-material interaction To promote cell integration and tissue
regenerationTo study material structure-function.
Present actives:Therapeutic cells, peptides, proteins, analgesics, antimicrobials, immunocytokines as soluble or immobilized PEGylated molecules
To influence cell-material interaction,To enhance clinical utility.
Extracellular matrix (ECM) – mimics semi-interpenetrating networks (sIPN)
FODay 0
Day 21
sIPN-mediated wound healing in full thickness defects
Waldeck H, Kao WJ. J Biomaed Mat Res (2007), 82A, 861-871
sIPN with soluble KGF and grafted RGD(day 21)
sIPN w/o loaded biomolecules(day 21)
Conventional cotton dressing with Ag (day 21)
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sIPN-mediated wound healing in partial defects
Acticoat™ graft Tisseel/Telfa graft IPN graft Xeroform
3 weeks later:
sIPN promotes healing by modulating monocyte, fibroblast, keratinocyte paracrine regulation
This image cannot currently be displayed.
Expanding sIPN clinical utility as a drug delivery matrixpharmaceuticals: AgSD, Bupivacaine to manage co-morbidity
• released silver sulfadiazine maintained bioactivity in bacteria kill efficiency
S. Aureusfreshly plated ----confluent ––
methicillin resistant S. aureusfreshly plated ----confluent ––
P. aeruginosafreshly plated ----confluent ––
Drug loaded sIPN
Area of bacterial kill
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L-WBG
No WBGS-WBG
M-WBG
Expanding sIPN clinical utility as a drug delivery matrixpharmaceuticals: WBG® reactive oxygen species scavenger
PMNs
Chamber A
Chamber B
OxyBurst H2HFF-BSA+
PMA
Extracellular ROSprobe
Stimulates ROS production by PMNs
0
5
10
15
20
L-WBG M-WBG S-WBG No WBG
Equ
ival
ent
fluor
esce
in M
FI (
nM)
a decrease in detected ROS with the addition of L-WBG
Chamber AChamber B
Advanced Wound Healing Therapy
Cell-based therapy strategies
New therapeutic paradigm:using biomaterials and therapeutic cells to recapitulate the lost tissue structure and to address underlying disease to improve healing.
Adapted from Clark et al.J Invest Derm 2007
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Epidermal, dermal, epidermal/dermal equivalents
Epidermal constructs (permanent transplant):
Autologous keratinocytes on various substrates
CellSpray®, Epicel®, Epidex®, EPIBASE®, MySkin®
Dermal constructs (permanent to temporary usages):
Decellularized ECM, neonatal allogeneic fibroblasts oncollagen
Alloderm®, SureDerm®, Matriderm®, OASIS®, EZ Derm®
Transcyte®, Dermagraft®, Hyalograft®
Epidermal/dermal equivalents (temporary applications):
Allogeneic keratinocytes/fibroblasts on collagen
Apligraft®, Orcel®, PolyActive®
Primary mode of action is to deliver cell-derived factors
Room for improvement
Epidermal constructs (permanent transplant):+3 weeks waiting period for autologous cells to expand
Not effective in full thickness wounds or acute care
Cost
Dermal constructs (permanent to temporary usages):Compositionally complex ECM
Although immune tolerant, allogeneic fibroblasts undergofunctional changes during established entrapment methodsand storage
Requires second procedure for removal
Epidermal/dermal equivalents (temporary applications):+4 weeks of complex, labor-intensive manufacturing process
Cost
Requires second procedure for removal
Entrap therapeutic cells within sIPNfacile, in situ forming, organogenetic epidermal/dermal equivalent to deliver cell-derived healing promoting factors to the wound bed
PEG-dithiolPEGdA
Mix
+ +
Therapeutic cells in suspension
Cell encapsulated sIPN matrix
Gelatin
Gelatin modified with biofunctional peptides
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Feasibilityin-gel cells maintained viability +14 days in vitroin vivo in situ gel formation post subcutaneous injectionmaterial-modulated keratinocyte-fibroblast interaction
viability
active cell-materialinteraction
activecytoskeletalformation
In vivo tissue-sIPN interface post sub-q injection
modulation ofprotein release
Promising therapeutic cells to be delivered via sIPN
Allogeneic human dermal fibroblasts/keratinocytesclinical experience
Mesenchymal stem(stromal) cells (MSC)easily accessible, multiple tissue sources
positive for mesodermal lineage markers CD29, CD44, CD90
negative for hematopoietic marker CD14upon proper stimuli, differentiable to various lineages
immune tolerant and inflammatory modulatory
Human epithelial progenitor cells (NIKS®)genetically identical, proliferative
undergo normal epidermal differentiation
long-lived phenotype enables stable transfection
Allogeneic BM-MSC injected into partial thickness wounds dressed with: Acticoat, Tisseel, Autograft, sIPN in pigs
MSC improved macroscopic wound healing (VSS: vascualrity,pigmentation, pliability and height),
However, delivered MSC only lasted up to 7 days in vivo.
sIPN with MSCMSC Tissue MSC MSC + sIPN
in 7 d in 7d
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The role of hyperbaric oxygen therapies (HBO2T):Increased native circulating MSC mobilization and wound recruitment in diabetic patients *
* Thom SR et al. Wound Rep Regen. 2011, 19, 149-161.
Circ endothelialProgen cells
Lower extremity wound margin with HIS for HIF-1,endothelial progenetor cell markers CD34, CD133after 3 wk of HBO2T
HBO2T increased:
circulating endothelial progenetor cells (L)
and
platelet NOS activity (R)in
diabetic patients undergoing treatments
vs. healthy patients
NIKS®genetically modified to overexpress VEGFpromote HuMVEC proliferation in vitroseeded onto gelatin, cultured, transplanted into full-thickness wounds in
db/db diabetic mice resulted in improved healing
Future challenges for biomaterial-enabled cell-based advanced wound therapies
Difficult to harmonize various pre-clinical & clinical resultsMultiple delivery matrices
(hyalluronic acid, alginate, chitosan, fibrin, synthetic hydrogels)
Multiple cell sources and manipulation methods(autografts vs allografts vs xenografts)
Multiple methods of cell introduction(timing as a function of wound progression, injection vs implant)
Incomplete understanding of the mode of action(engraftment vs paracrine regulation)
Commercializationscale-up, manufacturing, batch consistency, regulatory pathway,
cost, competitiveness over other methods of care
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What’s Next?
Going beyond basic science research in academia
Traditional role of university in translational research:idea generation, patent prosecution, licensing
Idea or invention
Research Prototyping
Manufacturing
Initial clinical safety testing
Clinical trials Commercialization
Regulatory (FDA) review
Patent application
US Patent Office review Traditional licensing window
Patent issued
Highestcommercial risk
Lowestcommercial risk
traditional role of university
Problems with the old model:
Investors and industry increased cost sensitivity and risk aversion.
Lack of commercial pathways for numerous issued patents held by universities.
Too few promising drugs and devices in development pipeline to tackle current clinical needs.
Formation of National Center for Advancing Translational Sciences at the National Institutes of Health (US).
Mission: to “de-risk” promising technologies so they are attractive to potential licensers for product development commercialization.
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Paradigm Shift:the role of university in “de-risking” a technology
Idea or invention
Research Prototyping
Manufacturing
Initial clinicalsafety testing
Clinical trials Commercialization
Regulatory (FDA) review
Patent application
US Patent Office review Traditional licensing window
Patent issued
Current licensing window
traditional role of university
PARADIGM SHIFT: redefined role of university ?
Highestcommercial risk
Lowest commercial risk
“de-risking” = “value-added”
Roadmap for FIM study: a collaborative effort
1. Establish manufacturing process for sIPN base formulation
2. “product” validation and verification
3. Complete a first-in-human safety trial in a controlled and clinically relevant model: skin donor graft site wounds in traumatic acute wound patients
4. Later project may address sIPN in other types of wound and/or to present actives.
Key Benchmarks: unfamiliar territory for academia
• Develop packaging system and methods
• Determine sterilization methods
• Develop manufacturing processes
• Design Verification and Validation testing
• Complete additional animal studies (if needed)
• Complete Biocompatibility tests
• Develop first-in-man (FIM) Protocol
• Approval from governing body for clinical human use
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Challenges for technology translation in academia
• Alignment with institutional missions and priorities.
• Ability to predict market needs
• Ability to select and to develop commercialization pathways for numerous issued and filed patents in the portfolio.
• Lack of quality systems and know-how’s in “product” development to “de-risk” promising technologies in medical devices, drugs or combination products.
• Lack of human resources and capitals to pursuit business ventures.
General Conclusions:
Wound healing remains a pressing clinical challenge.
Innovation and interdisciplinary approaches are absolutely essential to develop advanced wound therapies.
Biomaterial-enabled, cell-based approaches coupled with existing practices such as HBO2T are promising in improving current therapies, patient management, and healing outcome.
Technology translation pathways and know-how’s from academia to industry remain a challenge to fully realize
the clinical impact of promising technologies.
Thank You !W. John Kao