NANOFIBER SCAFFOLD ARCHITECTURE DRIVES OSTEOGENESIS OF MARROW STROMAL CELLS BY INDUCING CHANGES IN CELL MORPHOLOGY AND GENE EXPRESSION

Christopher K. Tison, Girish Kumar, Kaushik Chatterjee, Carl G. Simon Jr.

Utilizing tissue scaffold architecture to induce stem cell differentiation is of tremendous importance to the regenerative medicine community. To this end, we have investigated the effect of nanofiber scaffolds on primary human bone marrow stromal cell (hBMSCs) differentiation. hBMSC function was tested on biocompatible poly-(ε-caprolactone) (PCL) nanofibers.  Flat spun coat surfaces of the same material (PCL) were used as controls so that the same material chemistry could be tested in a 2D format. The PCL nanofiber scaffolds induced osteogenic differentiation and mineralization of hBMSCs but PCL films did not. Since cell differentiation is tightly linked to cell morphology, we used high-resolution confocal microscopy to measure and compare cell morphology on PCL nanofibers and films. hBMSCs cultured on PCL nanofibers had an elongated morphology with significantly lower roundness, higher branching, and a decreased area as compared to hBMSCs cultured on spun coat PCL surfaces. Further, we have compared cellular morphologies during osteogenesis driven by nanofibers to that driven by biochemical supplements (dexamethasone, ascorbic acid, β-glycerophosphate). We find that supplements induce hBMSCs to adopt morphologies similar to that found on nanofibers, suggesting that elongated and branched cell morphologies can induce osteogenesis. Finally, gene expression analysis for a library of nanofiber and spun coat scaffolds has revealed statistical similarities in the gene expression of stem cells driven towards osteogenesis via either chemical cues or structural features. Future work will focus on characterizing 3D nanofiber mats to understand how scaffold architecture can drive cell behavior.