Breast Reconstruction with a Tissue Engineering and … · 2019-12-23 · Review Breast Reconstruction with a Tissue Engineering and Regenerative Medicine Approach (Systematic Review)

Review

Breast Reconstruction with a Tissue Engineering and Regenerative

Medicine Approach (Systematic Review)

E. DONNELY ,1 M. GRIFFIN,1,2 and P. E. BUTLER1,2

1Division of Surgery and Interventional Science, University College London,Royal Free Hospital Campus, London, UK; and 2Department of Plastic Surgery, Royal Free Hospital, London, UK

(Received 1 August 2019; accepted 21 September 2019; published online 1 October 2019)

Associate Editor Eric M. Darling oversaw the review of this article.

Abstract—Current techniques for breast reconstructioninclude an autologous-tissue flap or an implant-based pro-cedure, although both can impose further morbidity. Thissystematic review aims to explore the existing literature onbreast reconstruction using a tissue engineering approach;conducted with the databases Medline and Embase. A totalof 28 articles were included, mainly comprising of level-5evidence with in vitro and animal studies focusing on utilizingscaffolds to support the migration and growth of new tissue;scaffolds can be either biological or synthetic. Biologicalscaffolds were composed of collagen or a decellularized tissuematrix scaffold. Synthetic scaffolds were primarily composedof polymers with customisable designs, adjusting the internalmorphology and pore size. Implanting cells, includingadipose-derived stem cells, with combined use of basicfibroblast growth factor has been studied in an attempt toenhance tissue regeneration. Lately, a level-4 evidence humancase series was reported; successfully regenerating 210 mL oftissue using an arterio-venous pedicled fat flap within a tissueengineering chamber implanted on the chest wall. Furtherresearch is required to evaluate whether the use of cells andother growth factors could adjust the composition ofregenerated tissue and improve vascularity; the latter a majorlimiting factor for creating larger volumes of tissue.

Keywords—Breast reconstruction, Tissue engineering, Re-

generative medicine, Scaffold, Cellular therapy, Stem cells,

Adipose-derived stem cells.

INTRODUCTION

Breast cancer poses a significant problem, being themost common cancer in the UK female population. In2015 alone there were 54,800 new cases diagnosed,with incidence rates projected to increase 2% by theyear 2035.4 Despite this increase, better screening andtreatment options are leading to an improvement insurvival rates, meaning almost eight out of 10 womensurvive greater than 10 years after diagnosis.4 By theend of 2010, there was just under half a million womenin the UK living with a diagnosis of breast cancer. Andits not just affecting the UK, with an estimated twomillion new cases diagnosed worldwide in 2018.2

Following a diagnosis of breast cancer, 81% ofpatients undergo surgery to remove the primary tumor.4

This can be accompanied by neoadjuvant or adjuvantchemotherapy and radiotherapy, tailored according tothe individual case. Surgery, whether lumpectomy ormastectomy, has long been associated with a significantburden of disease; the disfiguring surgical procedureleading to psychological distress, loss of femininity,sexual dysfunction and even suicidal ideation.23,28

Breast reconstruction can be offered immediately atthe time of initial surgery in the case of neoadjuvanttherapy, or as a delayed procedure following anyrequired adjuvant therapy and necessary planning. Thetiming of reconstruction is highly dependant on suchtherapy, with a delayed autologous tissue flap moreindicative if postmastectomy radiation is required dueto an increased risk of capsular contracture or flapfailure if performed as an immediate procedure priorto radiation.26 Patients undergoing a mastectomy plusbreast reconstruction have a significantly decreasedincidence of anxiety and depressionwhen compared with

Address correspondence to E. Donnely, Division of Surgery and

Interventional Science, University College London, Royal Free

HospitalCampus,London,UK.Electronicmail: Edward.donnely10@

alumni.imperial.ac.uk

Annals of Biomedical Engineering, Vol. 48, No. 1, January 2020 (� 2019) pp. 9–25

https://doi.org/10.1007/s10439-019-02373-3

BIOMEDICALENGINEERING SOCIETY

0090-6964/20/0100-0009/0 � 2019 The Author(s)

9

http://orcid.org/0000-0003-0461-4846

http://crossmark.crossref.org/dialog/?doi=10.1007/s10439-019-02373-3&domain=pdf

mastectomy alone.6 Breast reconstruction provides anaesthetic benefit and the current standard of practice iseither an autologous tissue flap or implant based (siliconor saline) procedure. However both can impose furthermorbidity that should not be unheeded and require an in-depth discussion between clinician and patient evaluatingthe risks and benefits of each. The sequalae of an autol-ogous tissue flap includes the short-term complication offlap failure and long-term complications of fat necrosisand donor site morbidity17 while the silicone/saline im-plant based procedure incurs short-term risk of infectionand long-term risks of capsular contracture and implantrupture.15 Textured implants are at present under reviewdue to a possible association with anaplastic large celllymphoma.3 These risks emphasise the need for a newtechnique of breast reconstruction.

Since stem cells were first identified, scientists andhealth professionals alike have been working towardrepairing and replacing human tissue damaged sec-ondary to disease and trauma using tissue engineeringand regenerative medicine. Their aim of using autolo-gous cells to proliferate and replenish the desired tissuecould eliminate the long-term complications associatedwith either technique, such as capsular contracture orthe need to harvest an autologous flap and hence do-nor site morbidity.

The breast is composed of glandular and adiposetissue, the latter forming majority of the volume.Autologous fat grafting has been used to fill soft tissuedefects within the body, including the breast, althoughthe limitation of resorption and unable to maintainvolume for significant periods of time still persists.13

Cell-assisted lipotransfer involves the enrichment ofthe fat graft with adipose-derived stem cells, hypothe-sizing the ability to withstand longer periods ofhypoxia. Although one study still reported loss of 47%of the initial post-operative volume following breastaugmentation.24,34 To address this issue, the idea ofdesigning a support structure capable of providingstructural integrity to the developing tissue has beenhypothesized and is leading the way to a tissue engi-neered breast.

This article aims to explore and perform a system-atic review of the current literature on breast recon-struction using a tissue engineering and regenerativemedicine approach.

METHODS

A systematic review was conducted with the litera-ture databases Medline (OvidSP; 1946 to 6/12/2018)and Embase (Ovid; 1974 to 12/12/2018), adhering tothe PRISMA guidelines.

The search criteria was formulated to identify arti-cles on ‘breast reconstruction’ AND ‘tissue engineer-ing’. The base search filters for ‘breast reconstruction’included {MAMMAPLASTY/OR MASTECTOMY/(MeSH terms)} OR {‘‘breast reconstruct*’’ ORmamm?plasty OR mastectomy OR (breast ANDlumpectomy) (keywords)}. The base search filters for‘tissue engineering’ included {TISSUE ENGINEER-ING/OR BIOMEDICAL ENGINEERING/OR RE-GENERATIVE MEDICINE/(MeSH terms)} OR{(‘‘tissue engineer*’’ OR ‘‘biomedical engineer*’’ OR‘‘regenerative medicine’’ OR biomaterial* OR ‘‘addi-tive manufactur*’’ OR ‘‘3D print*’’ OR scaffold)(keywords)} OR {(TISSUE SCAFFOLDS/(MeSHterm) OR (‘‘tissue scaffold*’’ OR scaffold*) (key-words)) AND (lipofill* OR lipotransfer* OR ‘‘fatgraft*’’ OR ‘‘adipo* stem cell*’’ OR ‘‘adipo* derivedstem cell*’’ OR ADSC) (keywords)}.

The search was restricted to the English language.Letters and review articles were excluded. The inclu-sion criteria incorporated the use of animplantable scaffold ± cellular therapy to engineertissue for the purpose of breast reconstruction. Articlesregarding the use of commercially available breastimplants were excluded, as the aim of the review was tohighlight methods that reconstruct the breast withautologous tissue only and avoid the implantation andhence complications of permanent foreign devices.

RESULTS

The systematic review identified 28 articles com-prising mainly of level five evidence in vitro and animalstudies, and two level four evidence human case series(Fig. 1). Current techniques have focussed on twodifferent biological scaffolds (eight articles; Table 1)and 13 synthetic scaffolds (fifteen articles; Table 2) tomimic the shape and support of native breast tissue.One article the scaffold material was not stated. A

Medline (Ovid)154 ar�cles

Embase (Ovid)289 ar�cles

319 ar�cles

124 duplicate ar�cles removed

28 ar�cles included in the systema�c

review

289 ar�cles excluded

FIGURE 1. A flow chart illustrating the database search andexclusion criteria to identify the articles included.


DONNELY et al.10

TA

BL

E1.

Bio

log

ical

scaff

old

s:

syste

mati

cre

vie

wd

ata

extr

acti

on

.

Auth

ors

Title

Year

Journ

al

Stu

dy

aim

Stu

dy

model

Scaff

old

Scaff

old

—bio

logic

al/

synth

etic,

bio

/non-

bio

degra

dable

Volu

me/s

ize

of

scaff

old

Cell

thera

py

Cell

nic

he±

gro

wth

facto

r

Huss

and

Kra

t-z

Mam

mary

epithelia

lcell

and

adip

ocyte

co-c

ul-

ture

ina

3-D

matr

ix:

the

firs

tste

pto

ward

stissue-e

ngin

eere

dhum

an

bre

ast

tissue

2001

Cells

Tissues

Organs

To

culture

hum

an

mam

mary

epithelia

lcells

with

adip

ocyte

son

a3-D

bio

-lo

gic

alm

atr

ix

Invitro

model.

Colla

gen

gel

Bio

logic

al

Bio

degra

dable

Unknow

n—

gel

Hum

an

mam

-m

ary

epithe-

lialcells

with

adip

ose

tis-

sue

Dulb

ecco’s

modifi

ed

Eagle

sm

ediu

m(D

ME

M)

with

10%

feta

lcalf

seru

m(F

CS

)and

antibio

tics

DM

EM

/Ham

sF

12

with

in-

sulin

,tr

ansfe

rrin

,tr

i-io

doth

yro

nin

e,

hydro

cort

i-sone,

chole

rato

xin

,epithelia

lgro

wth

facto

r,7%

FC

S,

1.5

%adenin

eand

antibio

tics.

Tada

and

Fuji-

sato

Adip

ose

tissue

engin

eer-

ing

for

abre

ast

recon-

str

uction

(Confe

rence

abstr

act)

2012

Journalof

Tissue

Engineer-

ingand

Regenera-

tiveMedi-

cine

To

engin

eer

adi-

pose

tissue

usin

gdecellu

-la

rized

matr

ixobta

ined

from

rat

lungs

Invivo

anim

al

model

Ath

ym

icm

ice

Decellu

larized

rat

lungs.

Bio

logic

al

Bio

degra

dable

Unknow

nA

dip

ose

cell

line

3T

3-L

1A

circula

tory

culture

syste

m

Tsuji etal.

Sim

ple

and

longsta

ndin

gadip

ose

tissue

engi-

neering

inra

bbits

2012

Journalof

Artificial

Organs

To

engin

eer

long-

sta

ndin

gadi-

pose

tissue

without

FG

F2

Invivo

anim

al

model

New

Yeala

nd

white

rabbits

Poly

pro

pyle

ne

colu

mn

cage

with

pore

siz

e200um

Suspended

type

1col-

lagen

sponge

Synth

etic

and

Bio

-lo

gic

al

Bio

degra

dable

20

mm

dia

me-

ter

10

mm

thic

k-

ness

3.1

4m

Lcolla

-gen

sus-

pensio

n.

––

Debels

etal.

Susta

inable

fat

gra

ftin

g.

Optim

izin

gfa

tgra

ftin

gin

anin

vivo

tissue

engin

eering

cham

ber

model(C

onfe

rence

Abstr

act)

2013

Woundrepair

andregen-

eration

To

impro

ve

long

term

outc

om

eoffa

tgra

ftin

gby

addin

ga

novel

adip

ose

derived

matr

ix

Invivo

anim

al

model

Rat

model.

Adip

ose

derived

acellu

lar

matr

ic(A

DM

)

Bio

logic

al

Bio

degra

dable

2m

LM

inced

auto

lo-

gous

fat

Adip

ose

derv

ied

acellu

lar

matr

ix

Wang

etal.

Com

bin

ing

decellu

larized

hum

an

adip

ose

tissue

extr

acellu

lar

matr

ixand

adip

ose-d

erived

ste

mcells

for

adip

ose

tissue

engin

eering

2013

Acta

Bioma-

terialia

To

com

bin

ehD

AM

and

AD

SC

sfo

radip

ose

tissue

engin

eering

for

soft

tissue

de-

fect

repair

Invivo

anim

al

model

Nude

rat

mod-

el.

Decellu

larized

hum

an

adi-

pose

tissue

EC

M(h

DA

M)

Bio

logic

al

Bio

degra

dable

0.5

cm

91

cm

Hum

an

adi-

pose-d

erived

ste

mcells

hD

AM

Om

idi

etal.

Chara

cte

rization

and

assessm

ent

of

hyper-

ela

stic

and

ela

stic

pro

pert

ies

of

decellu

-la

rized

hum

an

adip

ose

tissues

2014

Journalof

Biome-

chanics

To

bio

mechani-

cally

chara

c-

terise

DA

Tscaff

old

sderived

from

various

adip

ose

depots

inth

ebody

Invitro

model.

Decellu

larized

adip

ose

tis-

sue

(DA

T)

Bio

logic

al

Bio

degra

dable

Unknow

n–

–


Breast Reconstruction with a Tissue Engineering and Regenerative Medicine Approach 11

further four articles were identified that describe thereconstruction of the nipple areolar complex (Table 3).

DISCUSSION

Scaffolds

Since the idea of a tissue engineered breast was firstproposed, researchers have been analysing materialssuitable to use as an implantable scaffold that wouldsupport growth and allow regeneration of host tissue.An ideal scaffold would combine the key principles ofbiodegradability, low immunogenicity, porous archi-tecture and structural integrity. The scaffold compos-ites can broadly be categorized into biological scaffoldsand synthetic scaffolds.

Biological Scaffolds

Eight articles were identified that utilized a biolog-ical scaffold. All were biodegradable and could be sub-divided into two techniques; either a collagen basedscaffold as a gel or sponge, or a decellularized tissuebased scaffold created from adipose tissue, rat lungs orporcine mammary glands.

Collagen-Based

Huss and Kratz published the first step towardregenerating human autologous breast tissue on a 3-Dbiological matrix.22 Human mammary epithelial cellswith adipose tissue were cultured in vitro on collagengel. The typical growth pattern comprised largeepithelial patches of fibroblast-like shaped cells withpreadipocytes in between acquiring a round shape andaccumulating lipids with time. Cells require adhesivematerials in order to survive and type I collagen isknown to have an excellent porous structure; a suit-able scaffold for cell migration and proliferation.20

Utilizing a polypropylene cage implanted into thebilateral fat pads of rabbits and injecting a 3.14 mLsuspension of minced type I collagen sponge and sal-ine, a study reported significant adipogenesis filling92.8 ± 6.6% of the cage volume after 12 months.42

Significant volumes of adipose tissue had been gener-ated from surrounding tissue, along with the endoge-nous production of growth factors essential foradipogenesis and angiogenesis. These included fibrob-last growth factor-2 (FGF2), vascular endothelialgrowth factor (VEGF), platelet-derived growth factor(PDGF), epidermal growth factor (EGF) and insulin-like growth factor-1 (IGF-1), that were all detectable inthe wound drainage fluid. Although the polypropylenecage used was non-absorbable and too hard for breast

TA

BL

E1.

co

nti

nu

ed

Auth

ors

Title

Year

Journ

al

Stu

dy

aim

Stu

dy

model

Scaff

old

Scaff

old

—bio

logic

al/

synth

etic,

bio

/non-

bio

degra

dable

Volu

me/s

ize

of

scaff

old

Cell

thera

py

Cell

nic

he±

gro

wth

facto

r

Debels

etal.

Advances

inT

issue

Engi-

neering;

aN

ovel

Technol-

ogy

Makin

gU

se

of

an

invivo

Vascula

rized

Cham

ber

2015

Acta Chirur-

gicaBel-

gica

To

engin

eer

tissue

usin

gA

dip

ogel

and

an

art

eri-

ovenous

loop

within

aT

EC

Invivo

anim

al

model

Rat

model.

Adip

ose

derived

acellu

lar

matr

ix(A

DM

)(A

dip

ogel)

within

apoly

carb

onate

perf

ora

ted

hem

ispheric

cham

ber.

Bio

logic

al

Bio

degra

dable

2m

L–

Adip

ose

derv

ied

acellu

lar

matr

ix

Gia

tsid

isB

reast

tissue

engin

eering:

Decellu

larized

scaff

old

sderived

from

porc

ine

mam

mary

gla

nds

(Confe

r-ence

abstr

act)

2015

Journalof

the

Ameri-

canCol-

legeof

Sur-

geons

To

investigate

the

eff

ectiveness

of

decellu

larizin

gporc

ine

mam

-m

ary

gla

nds

Invitro

model.

Decellu

larized

porc

ine

mam

mary

gla

nds

Bio

logic

al

Bio

degra

dable

20

cm

940

cm

93

cm

––


DONNELY et al.12

TA

BL

E2.

Syn

theti

cscaff

old

s:

syste

mati

cre

vie

wd

ata

extr

acti

on

.

Auth

ors

Title

Year

Journ

al

Stu

dy

aim

Stu

dy

model

Scaff

old

Scaff

old

—bio

logic

al/

synth

etic,

bio

/non-

bio

degra

dable

Volu

me/s

ize

of

scaff

old

Cell

thera

py

Cell

nic

he±

gro

wth

facto

r

Choetal.

Engin

eering

of

volu

me-

sta

ble

adip

ose

tissues

2004

Biomaterials

To

engin

eer

adi-

pose

tissue

usin

gm

echani-

calsupport

str

uctu

res

Invivo

ani-

mal

mod-

el

Ath

ym

icm

ice.

Dom

eshaped

sup-

port

str

uctu

refo

rmed

of

Poly

(gly

colic

acid

)(P

GA

)and

Poly

(L-lactic

acid

)(P

LLA

).

Synth

etic

Bio

degra

dable

0.1

2cm

3H

um

an

Pre

-adip

ocyte

sT

hro

mbin

—fibrinogen

solu

tion

with

hep-

arin

(form

ing

afib-

rin

gel)

Basic

fibro

bla

st

gro

wth

facto

r(b

FG

F).

Choetal.

Engin

eere

dadip

ose

tis-

sue

form

ation

en-

hanced

by

basic

fibro

bla

st

gro

wth

fac-

tor

and

am

echanic

ally

sta

ble

environm

ent

2007

CellTransplan-

tation

To

enhance

adi-

pose

tissue

regenera

tion

by

com

bin

ing

am

echanic

al

support

with

bF

GF

Invivo

ani-

mal

mod-

el

Ath

ym

icm

ice.

Dom

eshaped

sup-

port

str

uctu

refo

rmed

of

Poly

(gly

colic

acid

)(P

GA

)and

Poly

(L-lactic

acid

)(P

LLA

).

Synth

etic

Bio

degra

dable

0.1

2cm

3H

um

an

Pre

-adip

ocyte

sT

hro

mbin

—fibrinogen

solu

tion

with

hep-

arin

(form

ing

afib-

rin

gel)

Basic

fibro

bla

st

gro

wth

facto

r(b

FG

F).

Fin

dla

yetal.

Tis

sue-e

ngin

eere

dbre

ast

reconstr

uction:

bridgin

gth

egap

to-

ward

larg

e-v

olu

me

tis-

sue

engin

eering

inhum

ans

2011

Plasticand

Reconstruc-

tiveSurgery

To

engin

eer

tis-

sue

togeth

er

with

asupport

-iv

evascula

ture

ina

larg

eani-

malm

odel

Invivo

ani-

mal

mod-

el

Porc

ine.

Perf

ora

ted

poly

car-

bonate

cham

ber

with

apoly

(L-

lactide-c

o-g

ly-

colid

e)

sponge

inhalf

the

cham

bers

.

Synth

etic

Bio

degra

dable

78.5

mL

5m

Ladip

ose

tissue

flap

–

Hett

iara

chic

hi

etal.

The

eff

ects

ofbio

physic

al

and

bio

chem

ical

envi-

ronm

ent

on

pre

-adip

ocyte

diffe

rentia-

tion

(Confe

rence

abstr

act)

2012

JournalofTis-

sueEngi-

neeringand

Regenera-

tiveMedi-

cine

To

investigate

the

eff

ect

of

scaf-

fold

stiff

ness

on

adip

ocyte

dif-

fere

ntiation

Invitro

mod-

el.

Poly

acry

lam

ide

gel

Synth

etic

Bio

degra

dable

Unknow

n3T

3-L

1cells

Norm

alor

adip

ogenic

media

Shpais

man

etal.

One-s

tep

synth

esis

of

bio

degra

dable

cur-

cum

in-d

erived

hydro

-gels

as

pote

ntialsoft

tissue

fille

rsaft

er

bre

ast

cancer

surg

ery

2012

BioMacro-

molecules

To

develo

pa

cur-

cum

in-d

erived

hydro

gelfo

ruse

as

asoft

tissue

fille

rand

dru

gdeliv

ery

syste

m

Invitro

mod-

el.

Curc

um

in-d

erived

hydro

gel.

(Non-

toxic

Poly

(-eth

yle

ne

gly

col)

and

desam

ino-

tyro

syl-ty

rosin

eeth

yleste

r)

Synth

etic

Bio

degra

dable

Unknow

n-

Hydro

gel

––

Chhayaetal.

Susta

ined

regenera

tion

of

hig

h-v

olu

me

adi-

pose

tissue

for

bre

ast

reconstr

uction

usin

gcom

pute

raid

ed

de-

sig

nand

bio

manufa

c-

turing

2015

Biomaterials

To

investigate

PD

LLA

scaf-

fold

sfo

rpote

n-

tialto

engin

eer

hig

hvolu

me

adip

ose

tissue

Invivo

ani-

mal

mod-

el

Ath

ym

icnude

rats

.

Poly

(D,L

)-Lactide

poly

mer

(PD

LLA

).

Synth

etic

Bio

degra

dable

3cm

3H

um

an

um

bili

cal

cord

perivascula

rcells

for

6w

eeks.

Then

hum

an

um

bili

calvein

endoth

elia

lcells

(HU

VE

Cs).

Thro

mbin

—fibrinogen

solu

tion.



TA

BL

E2.

co

nti

nu

ed

Auth

ors

Title

Year

Journ

al

Stu

dy

aim

Stu

dy

model

Scaff

old

Scaff

old

—bio

logic

al/

synth

etic,

bio

/non-

bio

degra

dable

Volu

me/s

ize

of

scaff

old

Cell

thera

py

Cell

nic

he±

gro

wth

facto

r

Chhaya

etal.

Tra

nsfo

rmation

of

Bre

ast

Reconstr

uctionvia

Additiv

eB

iom

anufa

c-

turing

2016

ScientificRe-

ports(N

a-

ture)

To

assess

pre

-vascula

riza-

tion

and

adi-

pose

tissue

gro

wth

with

aP

CL

scaf-

fold

Invivo

anim

al

model

Imm

unocom

pete

nt

min

ipig

s.

Medic

algra

de

poly

capro

lac-

tone

(mP

CL).

Synth

etic

Bio

degra

dable

75

cm

3A

uto

logous

lipoaspirate

–

Morr

ison

etal.

Cre

ation

of

aLarg

eA

di-

pose

Tis

sue

Constr

uct

inH

um

ans

Usin

ga

Tis

sue-e

ngin

eering

Cham

ber:

AS

tep

For-

ward

inth

eC

linic

al

Applic

ation

of

Soft

Tis

sue

Engin

eering

2016

EBioMedicine

To

engin

eer

larg

eclin

i-cally

rele

-vant

vol-

um

es

of

adip

ose

tis-

sue

infe

-m

ale

patients

with

aT

EC

and

fat

flap

Invivo

hum

an

case

series

Wom

en

with

pre

vi-

ous

masec-

tom

ies.

Dom

eshaped,

hollo

w,

3m

mth

ick

perf

ora

ted

acry

liccham

-bers

.

Synth

etic

Non-b

iodegra

dable

140-3

60

mL

(custo

mm

ade)

Thora

codors

al

art

ery

perf

o-

rato

r(T

AP

)fa

tflap.

–

Wuetal.

Self-A

ssem

blin

gR

AD

A16-I

Peptide

Hydro

gelS

caff

old

Loaded

with

Tam

ox-

ifen

for

Bre

ast

Recon-

str

uction

2017

BioMedRe-

search

International

To

com

bin

eta

moxifen

and

apep-

tide

scaff

old

for

use

as

asoft

tissue

fille

rand

dru

gdeliv

ery

syste

m

Invivo

anim

al

model

Ath

ym

icm

ice.

Tam

oxifen

loade-

d—

RA

DA

16-I

peptide

hydro

-gel

Synth

etic

Bio

degra

dable

Un- know

n—

H-

ydro

gel

Hum

an

adi-

pose-d

erived

ste

mcells

(hA

DS

Cs)

Hig

h-g

lucose

DM

EM

supple

mente

dw

ith

10%

FB

S,

dexam

-eth

asone,

isobuty

l-m

eth

ylx

anth

ine,

in-

sulin

,in

dom

eth

acin

.

Xuetal.

Self-a

ssem

blin

gR

AD

A16-I

peptide

hy-

dro

gels

caff

old

loaded

with

tam

oxifen

for

bre

ast

reconstr

uction

follo

win

glu

mpecto

my

(Confe

rence

abstr

act)

2017

ClinicalThera-

peutics

To

com

bin

eta

moxifen

and

apep-

tide

scaff

old

for

use

as

asoft

tissue

fille

rand

dru

gdeliv

ery

syste

m

Invivo

anim

al

model

Ath

ym

icm

ice.

Tam

oxifen

loade-

d—

RA

DA

16-I

peptide

hydro

-gel

Synth

etic

Bio

degra

dable

Un- know

n—

H-

ydro

gel

Hum

an

adi-

pose-d

erived

ste

mcells

(hA

DS

Cs)

–

Xia

o etal.

Pre

-shaped

larg

e-v

olu

me

engin

eere

dvascula

r-iz

ed

pedic

led

adip

ose

flaps

ina

rabbit

model:

Atw

osta

ge

tissue

engin

eering

cham

ber-

based

pro

cedure

(Full

Text

not

availa

ble

)

2017

JournalofBio-

materials

andTissue

Engineering

To

engin

eer

adip

ose

tis-

sue

usin

ga

TE

Cand

adip

ose

flaps

Invivo

anim

al

model

Rabbits.

Tis

sue

Engin

eer-

ing

Cham

ber

(TE

C);

un-

know

nm

ate

rial

Synth

etic

Non-b

iodegra

dable

Unknow

nA

dip

ose

flaps

(0.8

mL)

with

vesselpedi-

cle

–


DONNELY et al.14

TA

BL

E2.

co

nti

nu

ed

Auth

ors

Title

Year

Journ

al

Stu

dy

aim

Stu

dy

model

Scaff

old

Scaff

old

—bio

logic

al/

synth

etic,

bio

/non-

bio

degra

dable

Volu

me/s

ize

of

scaff

old

Cell

thera

py

Cell

nic

he±

gro

wth

facto

r

Rossietal.

Decora

tion

of

RG

D-m

imetic

poro

us

scaff

old

sw

ith

engin

eere

dand

devital-

ized

extr

acellu

lar

matr

ixfo

radip

ose

tissue

regen-

era

tion

2018

Acta

Biomate-

rialia

To

cre

ate

ahybrid

scaff

old

form

ed

of

asynth

etic

poly

mer

and

decellu

lar-

ized

tissue

Invivo

anim

al

model

Ath

ym

icm

ice.

Hybrid

EC

M-O

PA

AF

scaff

old

EC

Mfr

om

decellu

lar-

ized

hA

SC

sO

PA

AF

—R

GD

-mim

etic

poly

(am

idoam

ine)

olig

om

er

macro

p-

oro

us

foam

.

Synth

etic

and

bio

-lo

gic

al

Bio

degra

dable

8m

mdia

me-

ter

3m

mth

ick-

ness.

–In

itia

llyF

GF

-2,

in-

sulin

,dexam

-eth

asone,

in-

dom

eth

acin

,IB

MX

prior

todecellu

lariza-

tion

O’H

allo

ran

etal.

Evalu

ating

anoveladip

ose

tissue

engin

eering

str

at-

egy

for

bre

ast

recon-

str

uction

post-

maste

cto

my.

(Confe

r-ence

Abstr

act)

2018

IrishJournalof

MedicalSci-

ence

To

assess

the

oncolo

gic

al

safe

tyof

AD

SC

shar-

veste

dfr

om

patients

fol-

low

ing

chem

oth

era

py

Invitro

model

Hydro

gels

of

2%

w/v

hyalu

ronic

acid

(29

cro

sslin

kin

gdensity

loaded

with

adip

o-

cyte

sat

6.7

%to

tal

gelvolu

me)

Synth

etic

Bio

degra

dable

Un- know

n—

H-

ydro

gel

Adip

ose

De-

rived

Ste

mC

ells

(AD

S-

Cs)

–

Gerg

es

etal.

Explo

ring

the

pote

ntialof

poly

ure

thane-b

ased

soft

foam

as

cell-

free

scaff

old

for

soft

tissue

regenera

-tion

2018

Acta

Biomate-

rialia

To

assess

the

bio

mechani-

caland

physio

chem

ical

pro

pert

ies

of

apoly

-ure

thane-b

ased

scaff

old

and

adip

ose

tissue

gen-

era

tion

Invivo

anim

al

model

CD

1fe

-m

ale

mic

e

Poly

(ure

thane)-

based

scaff

old

sS

ynth

etic

Bio

degra

dable

8m

mdia

me-

ter

4m

mth

ick-

ness.

––

Leong

etal.

ReF

ilx-s

ynth

etic

bio

degra

d-

able

soft

tissue

fille

rsfo

rbre

ast

conserv

ing

sur-

gery

inbre

ast

cancer

(Confe

rence

abstr

act)

2018

CancerRe-

search

To

evalu

ate

ReF

ilxas

asoft

tissue

fille

rfo

rbre

ast

conserv

ing

surg

ery

de-

fects

Invivo

anim

al

model

Yucata

nm

inip

-ig

s.

Poly

ure

thanes

(am

ino-

acid

based)

Synth

etic

Bio

degra

dable

Un- know

n—

h-

ydro

gel

––

Kaufm

an

etal.

Inte

rim

report

of

aclin

ical

regis

try:

669

patients

im-

pla

nte

dw

ith

a3-d

bio

ab-

sorb

able

mark

er

(Confe

rence

abstr

act)

2018

Annals

ofSur-

gicalOncol-

ogy

Inte

rim

report

tosum

marize

data

colle

cte

din

an

IRB

-appro

ved

Regis

try

Invivo

hum

an

case

series.

3-D

bio

absorb

able

impla

nt

(unknow

nm

ate

rial)

Unknow

nB

iodegra

dable

Unknow

n–

–



TA

BL

E3.

Nip

ple

are

ola

rco

mp

lex

scaff

old

s:

syste

mati

cre

vie

wd

ata

extr

acti

on

.

Auth

ors

Title

Year

Journ

al

Stu

dy

aim

Stu

dy

model

Scaff

old

Scaff

old

—bio

logic

al/

synth

etic,

bio

/non-

bio

degra

dable

Cell

thera

py

Cell

nic

he±

gro

wth

facto

r

Cao etal.

Tis

sue-e

ngin

eere

dnip

ple

reconstr

uction

1998

Plasticand

Reconstruc-

tiveSurgery

To

tissue

engin

eer

auto

lo-

gous

cart

ilage

inth

eshape

of

ahum

an

nip

ple

Invivo

anim

al

model

Porc

ine.

Plu

ronic

F-1

27

hydro

gel(p

oly

-eth

yle

ne

oxid

eand

poly

pro

py-

lene

oxid

ecopoly

mer)

.

Synth

etic

Non-b

iodegra

dable

(Scaff

old

dis

-solv

es

over

tim

e).

Auto

logous

chro

n-

dro

cyte

s.

–

Tie

rney

etal.

Bio

logic

colla

gen

cylin

der

with

skate

flap

techniq

ue

for

nip

-ple

reconstr

uction

2014

PlasticSurgery

International

To

reconstr

uct

the

nip

ple

usin

ga

bio

logic

colla

gen

cylin

der

with

skate

flap

Invivo

hum

an

case

series.

Rolle

dcylin

der

of

EC

Mcolla

gen

derived

from

por-

cin

esm

all

inte

sti-

nalsubm

ucosa

Bio

logic

al

Bio

degra

dable

––

Pashos

etal.

Atissue

engin

eere

dnip

ple

and

are

ola

com

ple

x(C

onfe

rence

abstr

act)

2015

Molecular

Therapy

To

desig

na

scaff

old

form

ed

of

adecellu

larized

whole

NA

Cfo

rtissue

engin

eer-

ing

Invivo

anim

al

model

Rhesus

Maca-

que

Non-

hum

an

pri-

mate

s.

Decellu

larized

NA

CB

iolo

gic

al

Bio

degra

dable

Rhesus

bone

mar-

row

-derived

ste

mcells

–

Pashos

etal.

Chara

cte

rization

of

an

acellu

lar

scaff

old

for

atissue

engi-

neering

appro

ach

toth

enip

ple

–are

ola

rcom

ple

xre

constr

uction

2017

Cells

Tissues

Organs

To

cre

ate

anonim

munogenic

scaff

old

from

adecellu

lar-

ized

NA

Cfo

ruse

as

an

onla

ygra

ftth

at

ispatient

specifi

c

Invivo

anim

al

model

Rhesus

Maca-

que

Non-

hum

an

pri-

mate

s.

Decellu

larized

NA

CB

iolo

gic

al

Bio

degra

dable

Bone

mar-

row

-derived

mes-

enchym

alste

mcells

(BM

SC

s)

from

rhesus

ma-

caques

a-m

odifi

ed

Eagle

sm

ed-

ium

(feta

lbovin

eser-

um

,L-g

luta

min

e,

penic

illin

,str

epto

-m

ycin

,am

phote

ricin


DONNELY et al.16

reconstruction, continuing the search for the appro-priate scaffold.

Decellularized Tissue

The search began to look at the concept of decel-lularizing tissue; using a solution to completely removethe cellular component leaving only the extracellularmatrix (ECM) to form a scaffold. Tada and Fujisato40

showed that rat lungs could be decellularized, injectedwith adipocytes and implanted into nude mice. Severalresearchers developed protocols for decellularizingadipose tissue11,32,40,43; decellularized adipose tissue(DAT), decellularized human adipose tissue ECM(hDAM) or adipose derived acellular matrix (ADM).To aid adipocyte infiltration and proliferation into thescaffold, and overall structure of the reconstructedbreast, it is crucial that the scaffold have similarbiomechanical properties and deformability to that ofnative breast tissue. Omidi et al.32 showed that DATscaffolds sourced from different areas of femalepatients (breast, subcutaneous abdominal region,omentum, pericardial depot or thymic remnant) all

exhibited linear elastic and hyperelastic propertiesalike, and were consistent with the previously reportedYoung’s modulus of adipose breast tissue36; an averagevalue of 3250 ± 910 Pa. Advantageously this wouldmean the DAT scaffolds could be sourced from any ofthe areas for commercial use and would demonstratesimilar stiffness and deformability as a natural breastunder gravity loading from prone to supine bodypositions.

Subcutaneously implanting the hDAM scaffolds(0.5 cm 9 1 cm) in a nude rat model exhibited aminimal inflammatory response after 30 days withoutobvious rejection, with initially well vascularizedgrafts.43 However from week 2 to 8, there was a sig-nificant decrease in graft vascularization; this wasthought due to a gap still present between the scaffoldand native adipose tissue. To improve graft vascular-ization, a femoral arteriovenous loop was trialled in-side a perforated tissue engineering chamber (TEC;formed of polycarbonate) containing 2 mL of ADMtermed ‘‘Adipogel’’ using a rat animal model.11 Atboth 6 and 12 weeks post implantation, the chambers

FIGURE 2. H&E stained cross sections demonstrating tissue scaffold. (a, b) At 6 weeks. avl = arteriovenous loop. The arrowsdemonstrate areas of tissue growth within the nubbins of the TEC and the diamond areas of un-remodeled Adipogel. (b) the brownstaining demonstrating viable fat cells. (c, d) exhibit scaffold at 12 weeks with substantially more viable adipose tissue. SourceDebels11



were half filled with well vascularized connective tissue(0.946 mL ± 0.161), but only containing 135 lL ± 76adipocytes along with some myocytes. The adiposetissue appeared to be away from the arteriovenousloop at the outer margin of the TEC, while muscle cellgrowth was at the arteriovenous loop origin near theinguinal-abdominal muscle intersection (Fig. 2). De-bels hypothesized this is either due to migrating stemcells or cell-to-cell signaling pathways from local nativetissue. Meanwhile all chambers demonstrated animmunological reaction and were encased by anexternal fibrotic capsule. Giatsidis19 took the decellu-larization concept further, applying the technique toporcine mammary glands. The resultant scaffold pre-served original morphology with histological analysisresembling native architecture of ECM and vascu-lar/ductal networks. This study also demonstrated thebenefit of harvesting adjacent glands together andmolding the scaffold to the required shape.

The major limitations of biological scaffolds includerapid enzymatic and hydrolytic degradation, alongwith a strong immunogenic response in vivo. Tech-niques have been developed to decrease the rate ofdegradation, such as enzymatic pre-treatment or cross-linking using various agents, which improve robustnessand maintain integrity; however the effectiveness canvary.30 A key requirement of the scaffold is to providemechanical support during regeneration until the tissueis mature enough to support itself, which unfortunatelybiological materials have been unable to guarantee.Hence current research is now focussing on utilizingsynthetic polymers.

Synthetic Scaffolds

Fifteen articles were identified that utilized syntheticscaffolds, with 13 different techniques. These com-prised of eleven biodegradable scaffolds and two non-biodegradable tissue engineering chambers (TEC) thatare to be removed once the tissue has generated.

The majority of these scaffolds are synthesized fromthermoplastic polymers and can be further sub-divideddepending on their structure; either a hydrogel filler ora solid structural support.

Hydrogel Structure

As with biological scaffolds, the biomechanical andbiochemical environment of synthetic scaffolds influ-ences adipocyte migration and proliferation. Het-tiarachichi et al.21 were investigating the stiffness of apolyacrylamide gel and effect on adipocyte differenti-ation in vitro. The most favourable matrices were thosethat had a similar stiffness to endogenous adipose tis-sue; Young’s moduli above 4.1 kPa elicited maximal

spreading of adipose cells, while moduli below 4.1 kPaa more spherical phenotype.

Along with providing a soft tissue support to re-place breast tissue, the idea that hydrogels could beused as drug delivery systems was hypothesized. Cur-cumin-derived hydrogels were synthesized frompoly(ethylene glycol) (PEG) and desaminotyrosyl-ty-rosine ethyl ester (DTE), that upon hydrogel degra-dation led to local release of active curcumin (CUR).37

Through a condensation polymerization protocol,different compositions of hydrogel could be synthe-sized that altered its overall properties, including cur-cumin concentration and swelling ability;CUR50PEG50 exhibited the most favourable withstable curcumin release and compression moduluscomparable with native breast tissue. In vitro analysisdemonstrated selective cytotoxicity against breastcancer cells, but no cytotoxicity to noncancerous pri-mary human dermal fibroblasts, further suggestingpromising use as a bioactive void filler for excisedcancerous tissue.

Additional attempts to engineer artificial therapeu-tic breast tissue led to the efficacious incorporation oftamoxifen into a self-assembled injectable polypeptide,RADA16-I.44 The hydrogel scaffold provided supportfor cell attachment and proliferation, with resultssuggesting the 3D environment enhanced toxicity oftamoxifen on breast cancer cells, while reducing theeffect on human adipose derived stem cells (hADSCs).After subcutaneous implantation into nude mouseanimal models, the scaffold formed a round mass withregular shape and clear edge, retaining its shape uponcompression. Although the scaffold was completelydegraded and absorbed within 7 days in vivo, high-lighting long-term persistence as the major challenge.For the time being, therapeutic benefits of bioactiveimplants in human based studies are limited inoncoplastic surgery, only providing tissue support anda tumor bed target for radiation therapy.25

Poly(urethane)-based scaffolds have shown promisefor use as hydrogel fillers to restore breast volume.18,27

A polyurethane-based soft foam (PUF) demonstratedfatigue resistance and tuneable mechanical propertiesby adjusting the ratio of poly(ethylene glycol) (PEG) topolyester (PE) segments. The optimum balance shownto be PUF 3/10 (PEG/PE) enhanced the hydrophiliccharacter of the scaffold, favouring efficacious diffu-sion of body fluids. Although degradation kineticsshowed after 6 months loss of more than 50% originalweight. In vivo the undifferentiated mesenchymal cellsattached themselves to the periphery of the scaffold,gradually infiltrating toward the centre. By day 91,initial loose fibromyxoid tissue had been partially re-placed by mature adipose tissue. Expectedly the scaf-


DONNELY et al.18

fold elicited a foreign body reaction, although only apartial fibrous capsule was noted up to 3 months.

Solid Structure

Several solid dome shaped support structures syn-thesized from polymers have been analysed. Choet al.9,10 indicated that a mechanically stable environ-ment is crucial to maintain engineered tissue volume,creating a poly(glycolic acid) matrix (PGA) coated inpoly(L-lactic acid) (PLLA). The structure was formedby molding strips of PGA mesh and then immersing inPLLA, and was able to withstand compressive forces,maintaining stable in vivo volume (0.12 cm3) at6 weeks. Although the domed structure was hollow,minimizing surface area for cell attachment whichwould make engineering large volumes of tissue diffi-cult.

A 3D printer has been utilized to design and create apoly(D,L)-lactide polymer (PDLLA) scaffold,8 allowingthe ability to customise size and shape of the engi-neered breast. Internal morphology of the scaffold,including porosity and pore size, can be tailored toindividual patients. The PDLLA scaffold (volume3 cm3) withstood contraction forces for at least6 months in vivo (nude rat model) and did not exhib-ited any mass loss. Pore sizes of 1.5 mm allowed fortissue and vascular ingrowth, with 81% of the overalltissue at 24 weeks composed of adipose tissue; themajority being host-derived adipocytes. Scaffolds wereassociated with minimal inflammatory reaction, inte-grating into the host body and surrounded by a fibroticcapsule that decreased as the scaffold degraded.

Chhaya et al.7 went on to develop another custom-made scaffold (volume 75 cm3), using medical-gradepolycaprolactone (mPCL) through additive biomanu-facturing. On the contrary to previous designs, theslowly degrading mPCL scaffold had a stiffness valuethree orders of magnitude higher than that of native

breast tissue, hypothesizing that newly regeneratedadipose tissue needed protection from compressive andshear forces until it had matured. Scaffolds were im-planted into immunocompetent minipigs and alloweda period of prevascularization before cellular addition(Fig. 3). Prevascularization allowed a platelet-richfibrin blood clot to form inside the large pore network,stimulating angiogenesis and the production of a wellvascularized connective tissue. It was hypothesizedthat altering the initial scaffold treatment protocol(empty scaffold vs. prevascularization plus cellularaddition) could modify the composition of connectivetissue to adipose tissue, tailoring the procedure foraesthetic augmentation or breast reconstruction. Uponexplantation there were no major signs of inflamma-tion within the tissue section or scaffolds, howeverthere were low-grade granulomatous reactionslocalized around the scaffold. The role of macrophagesis not fully understood, however Chhaya et al. stipu-late it could contribute to angiogenesis, with priorresearch potentially linking the two via the secretion ofvascular endothelial growth factor (VEGF) and pla-telet derived growth factor (PDGF).39

The major disadvantage of synthetic scaffoldscompared to biological scaffolds when seeding with celland tissue components is the lower cellular affinity tothe synthetic material. To improve this, Rossi et al.35

has attempted to combine the functionalities of asynthetic polymer with a biological matrix to engineera hybrid scaffold; although this would increase the costand complexity of the biomaterial. A RGD-mimeticpoly(amidoamine) oligomer microporous foam(OPAAF) was created by free radical polymerization.The hydrophilic 3D interconnected porous networkwas decorated and then decellularized to generate ahybrid adipose ECM-OPAAF construct (Fig. 4a). Thestudy describes an effective decellularization protocolthat maintains ECM architecture. While the original

FIGURE 3. ‘‘Overall concept of the prevascularization and delayed fat injection concept.’’ An empty scaffold is implanted onto thechest wall, and after a period of prevascularization, lipoaspirate is injected into the construct. Source: Chhaya et al.7



OPAAF scaffold had similar mechanical properties tothat of native adipose tissue, the hybrid ECM-OPAAFconstruct had a Young’s modulus of more than dou-ble; 10.5 ± 3.4 kPa. In vitro and in vivo analysisdemonstrated a strongly enhanced adipoinductivecapacity as a result of ECM decoration, with an in-crease of infiltrating native adipocytes (Figs. 4g and4p). The interfacial biocompatibility between host andscaffold was difficult to evaluate in the immunocom-petent mouse model, with a strong immune responseagainst the human ECM. Although in vitro co-culturewith human peripheral blood exhibited a more pro-regenerative macrophage response.

As with biological scaffolds, vascularization of alarge volume of regenerated tissue in synthetic scaf-folds has been one of the main limiting variables.Utilizing previous knowledge, a small experimental piganimal study focussed on the co-development of adi-pose tissue alongside a supportive vasculature.14

Pedicled fat flaps based on superficial circumflex iliacvessels were inserted into tissue engineering chambers(TEC; perforated polycarbonate) together with apoly(L-lactide-co-glycolide) (PLGA) sponge (volume78.5 mL). At 22 weeks (12 weeks after chamber re-moval) the initial 5 mL adipose tissue flaps had ex-

panded into a larger core of 56.5 mL adipose tissuesurrounded by a fibrous capsular rim, with growthassociated with adipocyte hyperplasia. One constructwas even transferred and survived on its pedicle in anadjacent submammary pocket. Even though the studyhas a small sample and no control group to comparethe PLGA sponge, it provides proof of principle thetechnique can be used on a larger scale.

The concept was further demonstrated in a rabbitanimal model.45 An 8 mL volume TEC was implantedsubcutaneously with a vessel pedicled 0.8 mL adiposeflap inserted. The flaps expanded containingadipose tissue within and after TEC removal at8 weeks, growth continued until stabilization at weeks12–24.

The proof of concept led to the creation of a largevolume of adipose tissue construct in humans.29 Astudy of five women who had had previous mastec-tomies incorporated a thoracodorsal artery perforator(TAP) fat flap within a TEC (perforated acrylic) (vol-ume 140–360 mL) under a submuscular plane (Fig. 5).At 6 months follow-up the TECs were removed. Whileonly successful in one patient, 210 mL of newly formedtissue with ‘‘macroscopic appearance and palpabletexture very similar to native adipose tissue’’ (Fig. 6)

FIGURE 4. (a) The decellularization protocol. (b–e) The scanning electron microscope (SEM) analysis of the constructs (scalebars: 100 lm for (b and c) 10 lm for (d and e)). (f) Successful decellularization with a reduction in DNA content. (g, p) The adipocyteinfiltration at 2 weeks and 4 weeks post implantation respectively. The hybrid ECM-OPAAF construct shows superioradipoinductive capacity. Source Rossi et al.35


DONNELY et al.20

provides evidence of the feasibility of a tissue engi-neering approach in humans.

Nipple–Areolar Complex

Even though the focus of this systematic review ison reconstructing the breast, the literature search re-turned four articles investigating the nipple-areolarcomplex (NAC) and it was deemed imperative to

mention. Thankfully nipple-sparing mastectomy isbecoming increasingly more common however noveltissue engineering reconstructive techniques must becompatible with both nipple-sparing and non-nipple-sparing techniques. The scaffold composites includedone collagen based, two decellularized tissue based andone thermoplastic polymer based.

Previously breast reconstruction had been aimed atimproving cosmesis and symmetry of female form withclothes on. Eventually more attention was attributedto the NAC to improve naked female form and skinflaps were constructed that could also be tattooed forpigmentation.38

As with the breast, a tissue engineering approachhas been proposed. Cao et al.5 described a simpletechnique by injecting a pluronic F-127 hydrogel see-ded with autologous chondrocytes into a swine animalmodel. Surrounded by a purse string suture led to thegeneration of stable cartilage tissue that at 10 weeksclosely resembled a NAC.

Additional attempts now include a rolled cylinder ofcollagen derived from the submucosa of porcine smallintestine being used in conjunction with a skate flap ina human based study.41 The outcome at the time ofsurgery ranged from 6 to 7 mm nipple projection, witha 30–50% loss at 6 months.

FIGURE 5. (a) demonstrates the 210 cm3 TEC. (b–d) The TAP fat flap design, the surgical procedure and the final result prior toclosing. Source Morrison et al.29

FIGURE 6. At 12 months, the tissue generated exhibitsadipose tissue covered by a fibrous capsule. SourceMorrison et al.29



Alternatively a decellularized NAC seeded withautologous cells to be used as an onlay graft is in initialstages of testing.33 The in vitro report demonstratespreservation of the NAC primary structures on amicroscopic scale with an effective decellularizationprotocol. Reseeding of the scaffolds with bone mar-row-derived mesenchymal stem cells exhibited initialattachment to the periphery, with cells migrating dee-per into the scaffold by day 7; 91% cell viability at 48 hand 67% undergoing proliferation by day 7.

Cellular Therapy and Growth Factors

The idea is to regenerate host tissue to replace ex-cised breast tissue and provide soft tissue support. Sofar different materials and properties of scaffolds havebeen characterized. The scaffold needs to providestructural integrity until regenerated tissue has ma-tured to support itself, upon which the scaffold de-grades (or is removed) leaving only host tissue. Thereare two main hypothesises to regenerate tissue withinscaffolds. Either scaffolds provide the space and envi-ronment for surrounding native cells to migrate intothe scaffold and proliferate or cells, ideally autologousto prevent immunogenicity, are implanted into scaf-folds and proliferate.

Fifteen of the aforementioned articles investigatedincorporation of cellular therapy to improve adipoge-nesis, including bone marrow derived stem cells, adi-pose derived stem cells (ADSCs), preadipocytes andlipoaspirate. Along with this, eight included use ofculture medium containing growth factors and pro-teins. While only one article evaluated the effect of aspecific growth factor and compared this with a con-trol group.

Chhaya et al.7 hypothesized that initial scaffoldtreatment strategy could be tailored according to theindication for the surgical procedure. An empty scaf-fold for post-mastectomy breast reconstruction wouldallow native cells to migrate in and generate organizedconnective tissue, avoiding risk of breast cancerrecurrence from using adipose progenitor cells. Whileimplanting autologous lipoaspirate into scaffolds foraesthetic breast augmentation would allow generationof higher composition of adipose tissue to connectivetissue, 47.32% ± 4.12, maintaining natural tactilesensation and mimicking morphology of the breast.

Others have likewise discovered that implantingautologous lipoaspirate into the scaffold resulted in thesignificant increase of viable adipose tissue12; althoughthe majority of originally inserted adipocytes had died,indicating neoadipogenesis. This can occur due to thepresence of adipose derived stem cells (ADSCs) withinlipoaspirate, being first isolated and reported by Zuket al.46 ADSCs are multipotent with potential to dif-

ferentiate into adipose tissue, osteocytes, chondrocytesor myocytes when cultured in the presence of specificdifferentiation factors. To direct ADSCs toward theadipose lineage in vitro, they can be cultured in high-glucose Dulbecco’s modified Eagle’s medium(DMEM) supplemented with 10% fetal bovine serum,dexamethasone, isobutylmethylxanthine, insulin andindomethacin.44 Though there is potential risk of im-planted ADSCs stimulating breast cancer recurrence,ADSCs have been isolated from breast tissue and ab-domen of patients treated with neoadjuvantchemotherapy and demonstrated better adipogenicpotential and improved oncological safety withdecreased expression of cancer driver genes.31

Once implanted, a trial studied the effect of a fibringel containing basic fibroblast growth factor (bFGF),concluding there was a significant increase in pre-adipocyte cell survival, neovascularization and volumeof generated adipose tissue when compared to a con-trol group.9 Cho et al. hypotheses two mechanisms forenhanced adipogenesis. Firstly that neovascularizationin fibrin gel may be enhanced by bFGF, leading tofactors secreted from vasculature endothelial cells thatare known to promote adipocyte precursors to migrateand proliferate.1,16 Secondly that bFGF may directlystimulate implanted preadipocytes to differentiate intoadipocytes.

Other factors effecting cell migration and prolifer-ation include the environment surrounding the cells,termed the cell niche. The hybrid ECM-OPAAFscaffold characterized previously35 demonstratedsuperior adipoinductive capacity and it was hypothe-sized this maybe due to the presence of adipokinesembedded within the ECM that were deposited byADSCs prior to decellularization. Cell signaling,whether in the form of cytokines, adhesion moleculesor cell-to-cell contact, is thought to be imperative intissue engineering. Immunohistochemical (IHC) anal-ysis of the hDAM scaffold developed by Wang et al.43

reported a well maintained composition of collagen,glycosaminoglycan and VEGF; the latter stimulatingangiogenesis and neovascularization. Although thescaffold lacked laminin, important in cell attachmentand adhesion. Implanting ADSCs into the scaffoldin vivo, the density of donor cells was preserved up toweek 4, but then decreased significantly to week 8. Onthe contrary, the density of host native cells signifi-cantly increased from week 4 to 8, indicating hosttissue integration and adipose tissue regeneration.What caused the initial survival and then loss ofADSCs? What caused the subsequent migration ofhost cells after 4 weeks of implantation? There re-mains a substantial unknown knowledge relating tothe interaction between scaffold, cellular addition andgrowth factors.


DONNELY et al.22

Lastly, to improve vascularization a study trialledinserting human umbilical cord perivascular cells(HUCPVCs) within fibrin gels containing heparin intoPDLLA scaffolds for 6 weeks in vitro and then uponimplantation into rat animal models, human umbilicalvein endothelial cells (HUVECs) were injected.8 Mi-croCT angiography reported a high degree of vascu-larization equally distributed throughout scaffolds, andHUVECs survived the 6 month implantation process,but self-assembled functional capillary networks wereonly observed around the periphery of the scaffolds.

Vascularization of Engineered Tissue

The optimal vascularization of the newly regener-ated tissue has proved a major challenge and althoughalready discussed in part previously, its importanceshould be highlighted further. Scaffolds may showadequate properties with in vitro and small animalmodels, although upon upscaling to larger animals oreven the female patient, issues can arise with insuffi-cient vascularization of central zones leading to tissuenecrosis. The most notable techniques identified in thisreview were the pre-vascularization concept and theinclusion of an arterio-venous loop.

Chhaya et al.7 hypothesized a novel pre-vasculariza-tion concept whereby a scaffold is implanted andallowed a period of 14 days prior to delayed fat injec-tion. This period allowed the formation of a blood clotwithin the scaffold’s interconnected porous network,consisting of platelets embedded within cross-linkedfibrin fibres and the endogenous production of growthfactors including fibronectin, vitronectin and throm-bospondin. The authors correlate this process to previ-ous literature, indicating the stimulation of a strongangiogenic response and the formation of highly orga-nized connective tissue. Following the 14 day period,delayed fat injection provided an adipogenic stimulusthat lead to the engineering of tissue filling the entire75 cm3 scaffold, with the composition of 47.32% adi-pose tissue. The initial connective tissue had beenmodified to contain highly vascular areas of fat tissueandno evidence of tissue necrosis over the 24-week studyperiod. To further the concept, it will need to be studiedutilizing a larger scaffold to assess the feasibility ofengineering clinically relevant volumes of adipose tissue.

Several articles evaluated the use of an arterio-ve-nous loop and the most successful to date has beenreported in a human case series. Morrison et al.29 im-planted a custom-made TEC in a submuscular pocketon the chest wall of female patients with prior mas-tectomy. A thoracodorsal artery perforator fat flapwas transposed into the TECs and upon TEC removal12 months later, 210 mL of tissue with macroscopic

appearance of fat had been engineered that bled whenpunctured, indicating good vascularization. Themechanism is not fully understood, but hypothesizedto be hypertrophy and hyperplasia, expanding theexisting tissue of the transposed fat flap. By stretchingof the overlying tissue and creating a non-collapsiblespace with the TEC, ischemia is likely to occur andtherefore enhance angiogenesis and the sprouting ofblood vessels from the vascular pedicle.

Study Limitations

The systematic review had several limitations. Asthe concept of a tissue engineered breast is still in itsinfancy, the authors’ protocols and techniques werediverse with no standardization. Along with relativelysmall sample sizes and low study powers, made anyform of comparison challenging. Lastly, 10 of thearticles were conference abstracts with limited infor-mation and the full text of one article was unavailable.

CONCLUSION AND FUTURE WORK

To conclude, current research in tissue engineeringis demonstrating promising results for the future ofbreast reconstruction. The most popular strategy fo-cusses on regenerating breast tissue using abiodegradable synthetic scaffold to support cellmigration and proliferation.

Exploring the literature has identified keys questionsrequiring further research, which can be divided intothree areas. Firstly the scaffold itself. The internalmorphology requires optimising to aid cell migrationand improve vascularization; the latter limiting thevolume of tissue generated. Together with whatamount of time is needed for the mature regeneratedtissue to be able to support itself, at which point thescaffold should degrade. This leads onto question thelong-term safety of the scaffolds with polymer degra-dation products unknown. Secondly, the addition ofcells. Will the use of stem cells or lipoaspirate improveadipogenesis or is it safer to allow native tissue tomigrate avoiding the oncogenesis risk? And lastly,what are the effects of specific growth factors on boththe tissue generated and the development of well-or-ganized vasculature?

ACKNOWLEDGMENTS

The authors would like to thank the correspondingauthors and publishers for giving full permission to re-use the figures illustrated in this article.



FUNDING

No funding was received for this article.

CONFLICT OF INTEREST

The authors hold no conflicts of interest.

OPEN ACCESS

This article is distributed under the terms of theCreative Commons Attribution 4.0 InternationalLicense (http://creativecommons.org/licenses/by/4.0/),which permits unrestricted use, distribution, andreproduction in any medium, provided you giveappropriate credit to the original author(s) and thesource, provide a link to the Creative Commonslicense, and indicate if changes were made.

REFERENCES

1Aoki, S., S. Toda, T. Sakemi, and H. Sugihara. Cocultureof endothelial cells and mature adipocytes actively pro-motes immature preadipocyte development in vitro. CellStruct. Funct. 28:55–60, 2003.2Bray, F., J. Ferlay, I. Soerjomataram, et al. Global CancerStatistics 2018: gLOBOCAN estimates of incidence andmortality worldwide for 36 cancers in 185 countries. CACancer J. Clin. 68(6):394–424, 2018.3Brody, G. S., D. Deapen, C. R. Taylor, et al. AnaplasticLarge Cell Lymphoma Occurring in Women with BreastImplants: analysis of 173 Cases. Plast. Reconstr. Surg.135:695–705, 2015.4Cancer Research UK. Breast Cancer Statistics. Availableat: https://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/breast-cancer#heading-Five. Accessed 29 Dec 2018.5Cao, Y. L., E. Lach, T. H. Kim, et al. Tissue-engineerednipple reconstruction. Plast. Reconstr. Surg. 102:2293–2298, 1998.6Chen, W., X. Lv, X. Xu, X. Gao, and B. Wang. Meta-analysis for psychological impact of breast reconstructionin patients with breast cancer. Breast Cancer 25:464–469,2018.7Chhaya, M. P., E. R. Balmayor, D. W. Hutmacher,and J. T. Schantz. Transformation of breast reconstructionvia additive biomanufacturing. Sci. Rep. 6:28030,2016.8Chhaya, M. P., F. P. W. Melchels, B. M. Holzapfel, J. G.Baldwin, and D. W. Hutmacher. Sustained regeneration ofhigh-volume adipose tissue for breast reconstruction usingcomputer aided design and biomanufacturing. Biomaterials52:551–560, 2015.9Cho, S. W., W. S. Kang, W. R. Jong, et al. Engineeredadipose tissue formation enhanced by basic fibroblastgrowth factor and a mechanically stable environment. CellTransplant. 16:421–434, 2007.

10Cho, S. W., S. S. Kim, J. Won Rhie, et al. Engineering ofvolume-stable adipose tissues. Biomaterials 26:3577–3585,2004.

11Debels, H. Advances in tissue engineering; a novel tech-nology making use of an in vivo vascularized chamber.Acta Chir. Belg. 115:104–110, 2015.

12Debels, H., X. L. Han, J. Palmer, et al. Sustainable fatgrafting—optimizing fat grafting in an in vivo tissue engi-neering chamber model. In: Wound Repair and Regenera-tion 2013: Conference: 23rd Annual Meeting of theEuropean Tissue Repair Society. Reims France. Confer-ence Publication: (var.pagings). 21(6), p. A63.

13Elfadl, D., V. Garimella, T. K. Mahapatra, P. L. McMa-nus, and P. J. Drew. Lipomodelling of the breast: a review.Breast 19:202–209, 2010.

14Findlay, M. W., J. H. Dolderer, N. Trost, et al. Tissue-engineered breast reconstruction: bridging the gap towardlarge-volume tissue engineering in humans. Plast. Reconstr.Surg. 128:1206–1215, 2011.

15Fischer, J. P., J. A. Nelson, E. Cleveland, et al. Breastreconstruction modality outcome study: a comparison ofexpander/implants and free flaps in select patients. Plast.Reconstr. Surg. 131:928–934, 2013.

16Fukumura, D., A. Ushiyama, D. G. Duda, et al. Paracrineregulation of angiogenesis and adipocyte differentiationduring in vivo adipogenesis. Circ. Res. 93:E88–E97, 2003.

17Gart, M. S., J. T. Smetona, P. J. Hanwright, et al. Autol-ogous Options for postmastectomy breast reconstruction: acomparison of outcomes based on the American College ofSurgeons National Surgical Quality Improvement Pro-gram. J. Am. Coll. Surg. 216:229–238, 2013.

18Gerges, I., F. Martello, C. Recordati, et al. Exploring thepotential of polyurethane-based soft foam as cell-free scaffoldfor soft tissue regeneration. Acta Biomater. 73:141–153, 2018.

19Giatsidis, G. Breast tissue engineering: decellularized scaf-folds derived from porcine mammary glands. In: Journal ofthe American College of Surgeons 2015: Conference: 101stAnnual Clinical Congress of the American College ofSurgeons. Chicago, IL. Conference Publication: (var.pag-ings). 221 (4 Suppl 2), p. e117.

20Glowacki, J., and S. Mizuno. Collagen scaffolds for tissueengineering. Biopolymers 89:338–344, 2008.

21Hettiarachichi, K. D., A. J. O’Connor, S. Leo, et al. Theeffects of biophysical and biochemical environment onpreadipocyte differentiation. J. Tissue Eng. Regen. Med.6(Suppl 1):263, 2012.

22Huss, F. R. M., and G. Kratz. Mammary epithelial cell andadipocyte co-culture in a 3-D matrix: the first step towardstissue-engineered human breast tissue. Cells Tissues Organs169:361–367, 2001.

23Jamison, K. R., D. K. Wellisch, and R. O. Pasnau. Psy-chosocial aspects of mastectomy: I. The women’s perspec-tive. Am. J. Psychiatry 135:432–436, 1978.

24Jung, H. K., C. H. Kim, and S. Y. Song. Prospective 1-yearfollow-up study of breast augmentation by cell-assistedlipotransfer. Aesthet. Surg. J. 36:179–190, 2016.

25Kaufman, C., J. Barone, M. Cross, et al. Interim report of aclinical registry: 669 patients implanted with a 3-D bioab-sorbable marker. Ann. Surg. Oncol. 25(Supplement 1):S99,2018.

26Kronowitz, S. J., and G. L. Robb. Radiation therapy andbreast reconstruction: a critical review of the literature.Plast. Reconstr. Surg. 124:395–408, 2009.

27Leong, W. L., S. Sharifpoor, and K. Battiston, et al. Re-Filx-synthetic biodegradable soft tissue fillers for breastconserving surgery in breast cancer (Abstract). In: Con-ference Proceedings of the 2017 San Antonio Breast Cancer


DONNELY et al.24

http://creativecommons.org/licenses/by/4.0/

https://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/breast-cancer#heading-Five



Symposium, 2017 December 5–9; San Antonio, TX.Philadelphia (PA): AACR; Cancer Res. 2018;78(4Suppl):Abstract nr P2-12-15.

28Markopoulos, C., A. K. Tsaroucha, E. Kouskos, et al. Im-pact of breast cancer surgery on the self-esteem and sexual lifeof female patients. J. Int. Med. Res. 37:182–188, 2009.

29Morrison, W. A., D. Marre, D. Grinsell, et al. Creation ofa large adipose tissue construct in humans using a tissue-engineering chamber: a step forward in the clinical appli-cation of soft tissue engineering. EBioMedicine 6:238–245,2016.

30Nair, L. S., and C. T. Laurencin. Biodegradable polymersas biomaterials. Prog. Polym. Sci. 32:762–798, 2007.

31O’Halloran, N., K. Gilligan, E. Dolan, et al. Evaluating anovel adipose tissue engineering strategy for breast recon-struction post-mastectomy. In: Irish Journal of Medical Science2018: Conference: 43rd Sir Peter Freyer Memorial Lecture andSurgical Symposium. Ireland, 187(Supplement 4), p. S59.

32Omidi, E., L. Fuetterer, S. Reza Mousavi, et al. Charac-terization and assessment of hyperelastic and elastic prop-erties of decellularized human adipose tissues. J. Biomech.47:3657–3663, 2014.

33Pashos, N. C., M. E. Scarritt, Z. R. Eagle, et al. Charac-terization of an acellular scaffold for a tissue engineeringapproach to the nipple–areolar complex reconstruction.Cells Tissues Organs 203:183–193, 2017.

34Ross, R. J., R. Shayan, K. L. Mutimer, and M. W. Ashton.Autologous fat grafting current state of the art and criticalreview. Ann. Plast. Surg. 73:352–357, 2014.

35Rossi, E., J. Guerrero, P. Aprile, et al. Decoration of RGD-mimetic porous scaffolds with engineered and devitalizedextracellular matrix for adipose tissue regeneration. ActaBiomater. 73:154–166, 2018.

36Samani, A., J. Zubovits, and D. Plewes. Elastic moduli ofnormal and pathological human breast tissues: an inver-sion-technique-based investigation of 169 samples. Phys.Med. Biol. 52:1565–1576, 2007.

37Shpaisman, N., L. Sheihet, J. Bushman, J. Winters, and J.Kohn. One-step synthesis of biodegradable cur-

cumin-derived hydrogels as potential soft tissue fillers afterbreast cancer surgery. Biomacromol 13:2279–2286, 2012.

38Sisti, A., L. Grimaldi, J. Tassinari, et al. Nipple-areolacomplex reconstruction techniques: a literature review. Ejso42:441–465, 2016.

39Spiller, K. L., R. R. Anfang, K. J. Spiller, et al. The role ofmacrophage phenotype in vascularization of tissue engi-neering scaffolds. Biomaterials 35:4477–4488, 2014.

40Tada, R., and T. Fujisato. Adipose tissue engineering for abreast reconstruction. In: Journal of Tissue Engineering andRegenerative Medicine 2012: Conference: 3rd TERMISWorld Congress 2012. Vienna Austria. Conference Publi-cation: (var.pagings), 6 (Suppl 1), p. 266.

41Tierney, B. P., J. P. Hodde, and D. I. Changkuon. Biologiccollagen cylinder with skate flap technique for nipplereconstruction. Plast. Surg. Int. 2014:194087, 2014.

42Tsuji, W., T. Inamoto, R. Ito, et al. Simple and long-standing adipose tissue engineering in rabbits. J. Artif. Org.16:110–114, 2013.

43Wang, L., J. A. Johnson, Q. Zhang, and E. K. Beahm.Combining decellularized human adipose tissue extracel-lular matrix and adipose-derived stem cells for adiposetissue engineering. Acta Biomater. 9:8921–8931, 2013.

44Wu, H., T. Zhou, L. Tian, Z. Xia, and F. Xu. Self-assem-bling RADA16-I Peptide hydrogel scaffold loaded withtamoxifen for breast reconstruction. BioMed. Res. Int.2017:3656193, 2017.

45Xiao, X., S. Zhou, J. Wan, et al. Pre-shaped large-volumeengineered vascularized pedicled adipose flaps in a rabbitmodel: a two stage tissue engineering chamber-based pro-cedure. J. Biomater. Tissue Eng. 7:261–268, 2017.

46Zuk, P. A., M. Zhu, H. Mizuno, et al. Multilineage cellsfrom human adipose tissue: implications for cell-basedtherapies. Tissue Eng. 7:211–228, 2001.

Publisher’s Note Springer Nature remains neutral with re-

gard to jurisdictional claims in published maps and institu-tional affiliations.



Documents

Breast Reconstruction with a Tissue Engineering and … · 2019-12-23 · Review Breast Reconstruction with a Tissue Engineering and Regenerative Medicine Approach (Systematic Review)