Multilayer cellular stacks of gelatin-hydroxyapatite fiber scaffolds for bone tissue engineering

Multilayer cellular stacks of crosslinked, electrospun 25 wt % hydroxyapatite (HA)-gelatin and pure gelatin fiber scaffolds, seeded with human fetal osteoblasts (hFOBs), were studied for up to 18 days in static and dynamic cell culture. Two types of stack models were investigated: a four-layer stack with cells seeded at the bottom surface of the first/top layer and the top surface of the fourth/bottom layer, so that the two middle layers were not seeded with cells with the aim to act as continuing conduits of culture medium and nutrients supply to the adjacent cell-populated zones; a three-layer stack with cells seeded at the bottom surface of each layer. hFOBs exhibited lower migration rate through the stack thickness for the 25 wt % HA-gelatin scaffolds as compared to the pure gelatin scaffolds, due to the small pores of the former. Hence, the regularly seeded three-layer stack maintained cell-free porous zones in all layers through which the culture medium could continuously perfuse, while good fusion was achieved at the interface of all layers via the cross-migrating cells with a preference to downwards vertical migration attributed to gravity. Dynamic cell culture conditions enhanced overall cell growth by about 6% for the regularly seeded three-layer stack. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 779-789, 2017.