Fluorapatite and fluorohydroxyapatite apatite surfaces drive adipose-derived stem cells to an osteogenic lineage

Hydroxyapatite (HA) scaffolds are common replacement materials used in the clinical management of critical-sized bone defects. This study was undertaken to examine the potential benefits of fluoridated derivatives of hydroxyapatite, fluorapatite (FA), and fluorohydroxyapatite (FHA) as bone scaffolds in conjunction with adipose-derived stem cells (ADSCs). If FHA and FA surfaces could drive the differentiation of stem cells to an osteogenic phenotype, the combination of these ceramic scaffolds with ADSCs could produce materials with mechanical strength and remodeling potential comparable to autologous bone. This study was designed to investigate the ability of the apatite surfaces HA, FA, and FHA produced at different sintering temperatures to drive ADSCs toward osteogenic lineages.

HA, FHA, and FA surfaces sintered at 1150 °C and 1250 °C were seeded with ADSCs and evaluated for cell growth and gene and protein expression of osteogenic markers at 2 and 10 days post-seeding.

In vitro, ADSC cells were viable on all surfaces; however, differentiation of these cells into osteoblastic lineage only observed in apatite surfaces. ADSCs seeded on FA and FHA expressed genes and proteins related to osteogenic differentiation markers to a greater extent by Day 2 when compared to HA and cell culture controls. By day 10, HA, FA, and FHA all expressed more bone differentiation markers compared to cell culture controls.

FA and FHA apatite scaffolds may promote the differentiation of ADSCs at an earlier time point than HA surfaces. Combining apatite scaffolds with ADSCs has the potential to improve bone regeneration following bone injury.