Electrospun composite polycaprolactone scaffolds for optimized tissue regeneration

There is evidence to suggest that the development of a stable microvasculature at the site of a critical-sized bone defect or fracture aids in repairing or regenerating bone. Identifying a tissue engineering scaffold that optimizes bone tissue and blood vessel development could improve regenerative capabilities. In this paper we study the proliferation and directed differentiation potentials of endothelial colony forming cells and mesenchymal stem cells cultured on electrospun polycaprolactone matrices and compare them with data obtained for composite polycaprolactone-hydroxyapatite, polycaprolactone-hydroxyapatite/β-tricalcium phosphate and polycaprolactone-small intestine submucosa electrospun matrices. Polycaprolactone-hydroxyapatite and polycaprolactone-hydroxyapatite/β- tricalcium phosphate fibers on average displayed a two-fold increase in fiber diameter and average pore-size area as compared with polycaprolactone or polycaprolactone-small intestine submucosa scaffolds. X-ray diffraction showed that significant additions of hydroxyapatite, hydroxyapatite/β-tricalcium phosphate and small intestine submucosa were present in the composite scaffolds. Incorporating hydroxyapatite or hydroxyapatite/β-tricalcium phosphate into the polycaprolactone fiber increased the modulus and ultimate tensile strength significantly. Both endothelial colony forming cell and mesenchymal stem cell proliferation was two-fold greater on polycaprolactone-small intestine submucosa scaffolds; whereas on polycaprolactone-hydroxyapatite and polycaprolactone- hydroxyapatite/β-tricalcium phosphate scaffolds only endothelial colony forming cell proliferation was observed to be significant. Alkaline phosphatase analysis for mesenchymal stem cell-seeded scaffolds indicated that only polycaprolactone-small intestine submucosa scaffolds displayed significant increases after 10 days of culture, suggesting an osteoblast phenotype. Electrospun polycaprolactone-small intestine submucosa scaffolds stimulated proliferation of both cell types and directed mesenchymal stem cell differentiation, providing a stable platform to investigate the potential of endothelial colony forming cell in directing bone tissue repair or regeneration.