1. A comparison study between natural and synthetic scaffolds, and their interaction with cells Elaine Steinke Mentor: Milind Gandhi Advisor: Dr. Frank K. Ko

2. 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)

3. Two kinds of scaffolds ProsConsTypes Natural Made naturally in body Break down in body over time Not every body makes silk 20+ different types of collagen Collagen Silk Keratin Elastin Synthetic FDA-approved Break down in body over time Not naturally occurring in the body Poly(lactic-co- glycolic) acid Other polymers

4. 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.)

5. Scaffold Preparations Materials Procedure Electrospinning schematic, drawn by Jason Michael Lyons, 2004

6. SEM observations Silk (7%) dissolved in HFIP (5000X)Silk (7%) + collagen (1%) in HFIP (5000X)

7. SEM observations PLAGA (15%) in HFIP (5000X)PLAGA (15%) + collagen (1%) in HFIP (5000X)

8. Statistics 7% silk + 1% collagen 7% silk15% PLAGA + 1% collagen 15% PLAGA Sample Size (N) 100 Mean (nm)440.51417.67442.70487.42 Std. Dev. (nm)258.94240.63265.08183.33 Min. (nm)311836119 Max. (nm)106094513881061

9. 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.

10. 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.

11. 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

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