Incorporation of osteoblasts (MG63) into 3D nanofibre matrices by simultaneous electrospinning and spraying in bone tissue engineering.

Nanofibre scaffolds are suitable tools for bone tissue engineering. Mimicking the extracellular matrix, they allow for cell growth and differentiation. However, in large 3D scaffolds, uniform cell colonisation presents an unsolved problem. Our aim was to design and analyse a method of colonising nanofibre scaffolds, combining electrospinning of fibres and electrospraying of cells, to determine its impact on cell survival, growth, and gene expression. The osteoblast-like cell line MG63 was suspended in medium and electrosprayed into growing scaffolds of poly-(l-lactic acid) (PLLA) or PLLA/Col-I blend nanofibres. Fluorescein diacetate (FDA) staining was used to determine survival and growth over a 22 d culture period. Expression of osteocalcin (OC) and type I collagen (Col-I) genes was determined by real time PCR. Fluorescence microscopy was used to analyse Col-I and OC deposition, as well as cell densities. While spraying distance and cell density in the spraying solution influenced survival and cell density, the combination of electrospinning and electrospraying did not negatively influence the maintenance of the osteoblast phenotype. Furthermore, VEGF induction in response to hypoxia was not suppressed, but modulated by polymer composition. Therefore, simultaneous electrospinning and electrospraying is a suitable tool in producing nanofibre based 3D cell seeded scaffolds.