A comparison study between natural and synthetic scaffolds, and their interaction

with cells

Elaine Steinke

Mentor: Milind Gandhi

Advisor: Dr. Frank K. Ko

Background – Definitions

Tissue Engineering – the application of principles and methods of engineering and life sciences toward fundamental understanding of structure-function relationships in normal and pathological mammalian tissues and the development of biological substitutes to restore, maintain or improve tissue function (NSF, 1988)

Tissue Scaffolds – a mechanically stable structure which is capable of functioning biologically in the implant site (Ko et al, 2001)

Two kinds of scaffolds

Pros Cons Types

Natural Made naturally in bodyBreak down in body over time

Not every body makes silk20+ different types of collagen

CollagenSilkKeratinElastin

Synthetic FDA-approvedBreak down in body over time

Not naturally occurring in the body

Poly(lactic-co-glycolic) acidOther polymers

Hypotheses

First hypothesis: It is possible to fabricate nanofibrous scaffolds from combinations of silk and collagen, and PLAGA and collagen.

Second hypothesis: Protein based scaffolds promote cell attachment and proliferation better than synthetic polymer scaffolds. (Results pending.)

Scaffold Preparations

Materials Procedure

Electrospinning schematic, drawn by Jason Michael Lyons, 2004

SEM observations

120010008006004002000

Fiber diameter (nm)

12

10

8

6

4

2

0

Fre

qu

en

cy

Mean = 417.67Std. Dev. = 240.634N = 100

7 % silk in HFIP

Silk (7%) dissolved in HFIP (5000X)Silk (7%) + collagen (1%) in HFIP (5000X)

120010008006004002000

Fiber diameter (nm)

20

15

10

5

0

Fre

qu

en

cy

Mean = 440.51Std. Dev. = 258.94N = 100

7 % silk and 1% collagen in HFIP

SEM observations

120010008006004002000

Fiber diameter (nm)

20

15

10

5

0

Fre

qu

en

cy

Mean = 487.42Std. Dev. = 183.334N = 100

15 % PLAGA in HFIP

PLAGA (15%) in HFIP (5000X)

1400120010008006004002000

Fiber diameter (nm)

20

15

10

5

0

Fre

qu

en

cy

Mean = 442.7Std. Dev. = 265.083N = 100

15 % PLAGA and 1% collagen in HFIP

PLAGA (15%) + collagen (1%) in HFIP (5000X)

Statistics

7% silk + 1% collagen

7% silk 15% PLAGA + 1% collagen

15% PLAGA

Sample Size (N)

100 100 100 100

Mean (nm) 440.51 417.67 442.70 487.42

Std. Dev. (nm) 258.94 240.63 265.08 183.33

Min. (nm) 31 18 36 119

Max. (nm) 1060 945 1388 1061

Conclusions, Part One

It is possible to fabricate nanofibrous scaffolds from combinations of silk and collagen, and PLAGA and collagen, using the solvent hexafluoroisoproponol.

Average fiber diameters were measured, and found to be of acceptable sizes to continue.

Cell Preparation and Culture

The cell line being used is rat heart endothelial cell. Approximately 350,000 cells are initially seeded on

the scaffolds. After 4 hours, scaffolds are transferred to new

plates, where any seeded cells will continue growing. Cell numbers are counted on each of the scaffolds

and recorded as day zero.

Future Work

Count cells on days three, seven and fourteen

Observe scaffold-cell interactions using the scanning electron microscope on days three, seven and fourteen

Acknowledgements

Dr. Sun’s lab members, Eda Yildirim and Saif Khalil