Title:
In vitro osteogenic differentiation of human amniotic fluid-derived stem cells on a poly(lactide-co-glycolide) (PLGA)-bladder submucosa matrix (BSM) composite scaffold for bone tissue engineering.

Abstract:
Stem cells have become an important component of tissue regeneration, as they are able to differentiate into various cell types if guided appropriately. It is well known that cellular differentiation is greatly influenced by the surrounding microenvironment. We have developed a composite scaffold system using a collagen matrix derived from porcine bladder submucosa matrix (BSM) and poly(lactide-co-glycolide) (PLGA). In this study, we investigated whether a composite scaffold composed of naturally derived matrix combined with synthetic polymers would provide a microenvironment to facilitate the induction of osteogenic differentiation. We first showed that human amniotic fluid-derived stem cells (hAFSCs) adhered to the composite scaffolds and proliferated over time. We also showed that the composite scaffolds facilitated the differentiation of hAFSCs into an osteogenic lineage. The expression of osteogenic genes, including RUNX2, osteopontin (OPN) and osteocalcin (OCN) was upregulated in cells cultured on the composite scaffolds incubated in the osteogenic medium compared with ones without. Increased alkaline phosphatase (ALP) activity and calcium content indicates that hAFSCs seeded on 3D porous BSM-PLGA composite scaffolds resulted in higher mineralization rates as the duration of induction increased. This was also evidenced by the mineralized matrix within the scaffolds. The composite scaffold system provides a proper microenvironment that can facilitate osteogenic differentiation of AFSCs. This scaffold system may be a good candidate material for bone tissue engineering.