Collagen nanofibres are a biomimetic substrate for the serum-free osteogenic differentiation of human adipose stem cells

Electrospinning has recently gained widespread attention as a process capable of producing nanoscale fibres that mimic native extracellular matrix. In this study, we compared the osteogenic differentiation behaviour of human adipose stem cells (ASCs) on a 3D nanofibre matrix of type I rat tail collagen (RTC) and a 2D RTC collagen-coated substrate, using a novel serum-free osteogenic medium. The serum-free medium significantly enhanced the numbers of proliferating cells in culture, compared to ASCs in traditional basal medium containing 10% animal serum, highlighting a potential clinical role for in vitro stem cell expansion. Osteogenic differentiation behaviour was assessed at days 7, 14 and 21 using quantitative real-time RT-PCR analysis of the osteogenic genes collagen I (Coll I), alkaline phosphatase (ALP), osteopontin (OP), osteonectin (ON), osteocalcin (OC) and core-binding factor-alpha (cbfa1). All genes were upregulated (>one-fold) in ASCs cultured on nanofibre scaffolds over 2D collagen coatings by day 21. Synthesis of mineralized extracellular matrix on the scaffolds was assessed on day 21 with Alizarin red staining. These studies demonstrate that 3D nanoscale morphology plays a critical role in regulating cell fate processes and in vitro osteogenic differentiation of ASCs under serum-free conditions.