tissue eng. cartilage final presentation (1)

8/10/2019 Tissue Eng. Cartilage Final Presentation (1)

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Tissue Engineeringof

CartilageEvan WitmerGregory Lynn


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Cartilage Basics

Ailments, Traditional Treatments, &Tissue Engineering

Six Current Publications Objective & Justification Methods & Materials Results

Summary

Acknowledgements

Overview


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What is Cartilage?

Gel-like connective tissue made

up of chondrocytes, collagen,proteoglycans, and other ECM

proteins

70-80%water

Avascular

no nutrients, no regeneration

3 types:

Hyaline (low-friction)

Elastic (epiglottis)

Fibrocartilage (shock absorbing)


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Ailments & Traditional Treatme

Causes: Trauma, chronic wea

developmental disorders, im

Little-to-no natural regen Autografts (self) / Allogr

transplantation of do Debridement (smoothing Marrow stimulation

Problems: site morbidity, lim

availability, immune responsPrimary Source: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3146065/


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Advent ofTissue Engineerin

Creates an embryonic-like environment that stimulates grow Custom-made scaffolds for strength, structure, and function Resulting structure is true self-regenerated tissue Single surgery required


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Objective: To better assess the applicability of the electrospinnintechnology for scaffold fabrication, through electrospinning six co(-hydroxy esters) and testing their characteristics

Electrospinning high surface area to volume ratio similar structural morphology to the fibrillar ECM

Poly(-hydroxy esters) biodegradable & FDA approved

IF: 5.68 - (200


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Methods & Materials

6 Poly(-hydroxy esters)spun into fibrous scaffolds

A.) PGAB.) PLGA5050

C.) PDLLA

D.)PLGA8515

E.) PLLA

F.) PCL

Analysis Coat in gold & SEM Apply load


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Results

Cell-Matrix Interaction (After 7 days) Remained on surface of PGA, PDLLA, PLGA5050, and PL

Chondrocytes integrated into PLLA & PCL Cellular proliferation

Chondrocytes Mesenchymal Stem Ce


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(201Objective: To describe the developmental physicochemical pro

silk fibroin scaffolds derived from high-concentrationaqueousolutions.

Silk fibroin in vivo degrades easily tailored & processed

More than 10% aqueous silk fibroin solution


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Methods & Materials

Silk fibroin scaffolds with

different initialconcentrations(in wt.%)

A.) 8%

C.) 10%

E.) 12%

G.) 16%,

Combined methodology Salt-leaching & freeze-

drying Create different

structures


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Results

All above 90% interconnectivityand79% porosity

~15% of pores larger than 300m Water up-take (30 days immersion)

Original weights No significant differencein

morphology Mechanical Properties

Silk-16& Silk-12values suitablefor meniscus and cartilageengineering

Compressive


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European Cel(2008)

Objective: To evaluate in vivo cartilaginous tissue formation by cseeded fibrin/PLGA hybrid scaffolds.

Joint replacement PGLA & fibrin scaffolds

in vitro promoted cartilage constructs


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Methods & Materials

fibrin/PLGA hybrid (A) PLGA scaffolds soaked in

chondrocyte-fibrin solution

Control: Chondrocytes seededintojust PLGA (B)

Implanted into dorsum of nudemice 4 weeks

A

B


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Results

Fibrin/PLGA hybrid superior Higher cell viability and

proliferation Superior cell distribution, cell-

matrix organization, overallECM production

Fibrin/PLGA

PLGA


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Biomac(2005

Objective: To combine the benefits of a photocrosslinkable netwthe desirable material HA for cartilage tissue engineering.

Hyaluronic Acid (HA) forms aggrecans (proteoglycan CSPCP) &

wound healing Hydrogels photoencapsulate chondrocytes

Easier to fill tight spaces and irregularly shaped defects


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Materials & Methods

Materials:

HA and methacrylic anhydrideform MeHA Polyethylene glycol

dimethacrylate (PEGDM) Swine chondrocytes Nude mice

Methods: Fabrication of MeHA & PEGDM Encapsulation by polymerizing with UV light Culture in nude mice 4, 6, and 8 week dissection


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Results

Mechanical properties linear slope at low strains

(


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Results Cell viability

Decrease in viability with increase inmonomer concentration

Effect of molecular weight wasnegligible

1 day (black) 1 w

immediate (black), 4 weeks (gray), 8 weeks (white)

Neocartilage formation After 4 weeks, all co

became opaque. StaGAG formation

As effective as the Pbased hydrogel


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(200IF: 8.

Objective: Study aims to form non-toxic composite and study meproperties and degradation of chitosan-HAin vitro.

New Material: water-soluble chitosan and oxidized hyaluroni

without toxic cross-linking Crosslinking action with amino functions

No photopolymerization to prevent prolonged irradiation, nophotosensitizer (toxic)

h d i l


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Methods & Materials

Materials: Chitosan

HA sodium Succinic anhydride Bovine chondrocytes

Methods Succinyl-CS and Aldehyde-HA

synthesized and lyophilized

Hydrogels formed by mixing ratios of1:9, 3:7, 7:3, 9:1

Schiffs base crosslinking reaction Encapsulation:

Mix cells with S-CS, Add A-HA to form gel


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Results

Cell adhesion 5:5 & 7:3 signif

greater than 3

Degradation rate strong correlation to ratio of S-

CS to A-HA more S-CS = slower weight loss


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Results

Cell proliferation and viability successful encapsulation

in a normal sphericalmorphology

promoted cell survival

Successful crospossible with mreagents


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(2004)IF: 8.31

Objective: To study the response of bovine chondrocytes on natichemically modified BC (Phosphorylation & Sulfation)

Bacterial cellulose (BC) has unusual material properties & deg

high water retention, fiber network, high wet tensile stre cost-effective mass producible BC mold

Lack of literature describing native mechanical properties forconstructs

M th d & M t i l


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Methods & Materials Materials

G. xylinus H

3PO

4

NH2SO3H Bovine chondrocytes

Methods G. xylinus grown & BCpurified Phosphorylation

BC-P1 (30 min), BC-P2 (2 hr)

Sulfation BC-S

Cultured human arterial cartilage for 8days collagen type II, plant-derived

cellulose, calcium alginate, and

tissue culture plastic

l


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Results

Modifications changedsurface morphology to

adhere more strongly

Strong immune responseto native BC

Modified BC showshigher growth at similarimmune response toalginate & tissue cultureplastic

R lt


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Results

Presence of cellingrowthpromisingfor scaffoldmaterialengineering

BC does notprematurelydifferentiate cellsto form fibroblasts


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Summary

Scaffold Materials:

Synthetics PGA, PLLA, PDLLA,

PLGA5050, PLGA8515, PCL Natural

Silk, Bacterial Cellulose, HA,Chitosan

Huge variety of materials

Techniques:

Electrospinning,Lyophilization,Injectable HydrogPhotopolymeriza

Cross-linkinggenerally determdegradation rate


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Future of Cartilage TE

Hydrogels mimicking ECM-like matrices Self-assembling nanoscaffolds Thermosensitive injectable materials Biomimetic novel materials (coral, silk, etc.)


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Acknowledgements

Dr. Abidian

Evan Witmer

Greg Lynn

tissue eng. cartilage final presentation (1)

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