Regulation of the osteogenesis of pre-osteoblasts by spatial arrangement of electrospun nanofibers in two- and three-dimensional environments

Orientation of extracellular matrix (ECM) fibrils contributes to the anisotropy of bones, but little is known about how fibril orientation induces osteoblastic responses. Here, biomimetic polycaprolactone/type I collagen (PCL/COL-1) nanofibers with aligned and random fiber arrangements were used as models to study their effects on pre-osteoblasts. Elongated cell morphology, accelerated cell migration, elevated alkaline phosphatase activity and calcium content, up-regulated expression of osteogenic markers and differential expression of integrins were observed for cells cultured on two-dimensional (2D) aligned nanofibers. To emulate in vivo tissue structure, three-dimensional (3D) cell/nanofiber constructs with cells embedded among nanofiber layers were built via layer-by-layer assembly. These showed that aligned nanofibers in the 3D constructs continuously induced cell polarization and promoted osteogenesis. These findings revealed that nanofiber alignment favored osteogenic differentiation of pre-osteoblasts, and demonstrated the potential of 3D cell/nanofiber construct as a model to study specific cell-material interactions in a physiologically relevant environment. From the Clinical Editor: In this novel study, biomimetic polycaprolactone/type I collagen nanofibers with aligned and random fiber arrangements were used to demonstrate their effects on pre-osteoblasts with an overall goal of improved orientation of extracellular matrix fibrils to optimize osteoblastic responses and improve osteogenesis for future therapeutic exploitation.