Abstract 1986: Protein Pre-coating of Elastomeric Tissue-Engineering Scaffolds: Extracellular Matrix Formation and Phenotypic Changes of Circulating Endothelial Progenitor Cells
BACKGROUND: Optimal cell sources and scaffold chemistry for cardiovascular tissue engineering (TE) remain unknown. We investigated seeding endothelial progenitor cells (EPC) on elastomeric poly(glycerol sebacate) (PGS) scaffolds. We hypothesized that EPC proliferation and ECM formation could be enhanced by pre-coating PGS scaffolds with ECM proteins.
METHODS: PGS scaffolds were pre-coated with laminin (LM), fibronectin (FN), fibrin, collagen types I/III (Coll I/III), or elastin (EL) (n = 5; control = uncoated). Characterized ovine peripheral blood EPC were seeded onto scaffolds for 3 days followed by 14 days in a laminar fluid flow system.
RESULTS: EPC were CD31+, vWF+ and α-SMA− prior to seeding confirmed by immunohistochemistry (IHC) and immunoblotting. Both pre-coated and uncoated scaffolds demonstrated primary surface expression of CD31+ and vWF+ cells; α-SMA+ cells were found both on the surface and in the “interstitium” of the scaffold evidenced by IHC. Pre-coated scaffolds revealed significantly increased α-SMA+ cells and correlated with increases in percent positive area of FN (measured by morphometry), cellularity and collagen content (measured by biochemical assays) compared with uncoated controls (Table 1⇓). Histology demonstrated uniform expression of LM and FN within the surface and ”interstitium“ comparable to native valve. In contrast, Coll I/III were expressed in the surface and produced by both CD31+ and α-SMA+ cells. Moreover, flexure testing demonstrated decreased effective stiffness of the seeded scaffolds compared with unseeded controls (5.49 ± 0.38 vs. 8.13 ± 0.17 kPa, p ≤ 0.001).
CONCLUSION: Pre-coating elastomeric PGS scaffolds with ECM proteins, in particular FN, yielded enhanced ECM formation through phenotypic modulation of progenitor cells. These studies suggest the utility of a single cell source for construction of autologous heart valves, thereby contributing to optimization of TE pulmonary valve leaflet design.