Protein Precoating of Elastomeric Tissue-Engineering Scaffolds Increased Cellularity, Enhanced Extracellular Matrix Protein Production, and Differentially Regulated the Phenotypes of Circulating Endothelial Progenitor Cells

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Abstract
Background— Optimal cell sources and scaffold-cell interactions remain unanswered questions for tissue engineering of heart valves. We assessed the effect of different protein precoatings on a single scaffold type (elastomeric poly (glycerol sebacate)) with a single cell source (endothelial progenitor cells). Methods and Results— Elastomeric poly (glycerol sebacate) scaffolds were precoated with laminin, fibronectin, fibrin, collagen types I/III, or elastin. Characterized ovine peripheral blood endothelial progenitor cells were seeded onto scaffolds for 3 days followed by 14 days incubation. Endothelial progenitor cells were CD31 + , vWF + , and α-SMA − before seeding confirmed by immunohistochemistry and immunoblotting. Both precoated and uncoated scaffolds demonstrated surface expression of CD31 + and vWF + , α-SMA + cells and were found in the “interstitium” of the scaffold. Protein precoating of elastomeric poly (glycerol sebacate) scaffolds revealed significantly increased cellularity and altered the phenotypes of endothelial progenitor cells, which resulted in changes in cellular behavior and extracellular matrix production. Moreover, mechanical flexure testing demonstrated decreased effective stiffness of the seeded scaffolds compared with unseeded controls. Conclusions— Scaffold precoating with extracellular matrix proteins can allow more precise “engineering” of cellular behavior in the development of tissue engineering of heart valves constructs by altering extracellular matrix production and cell phenotype.