Short-term exposure to TNF-α promotes odontogenesis of stem cells of apical papilla on nanofibrous poly(l-lactic acid) scaffolds

Abstract

The aim of this study was to investigate the effect of short-term (3 days) preconditioning with pro-inflammatory cytokine tumor necrosis factor-alpha (TNF-α) on proliferation and odontogenic differentiation of stem cells of apical papilla (SCAP) seeded on a 3D scaffold. Our results showed that while TNF-α preconditioning at various concentrations did not affect SCAP proliferation, it enhanced alkaline phosphatase (ALP) activity and mineralized matrix deposition in culture. Preconditioning SCAP using TNF-α at a concentration of about 1 ng/ml optimally enhanced odontogenic gene expression of SCAP in culture. Highly porous nanofibrous (NF) poly(l-lactic acid) (PLLA) scaffolds, with nanofiber features mimicking the environment of the extracellular matrix, were fabricated using a thermally induced phase separation method. TNF-α preconditioning of SCAP at 1 ng/ml promoted ALP activity, calcium deposition and mineralized tissue formation of SCAP cultured on 3D NF-PLLA scaffolds in vitro. Moreover, TNF-α preconditioning at a concentration of 1 ng/ml promoted the formation of more mineralized tissue as well as stronger DSPP expression of SCAP seeded on NF-PLLA scaffolds in vivo. Collectively, this study suggests that short term TNF-α preconditioning, mimicking the transiently low concentration TNF-α present during inflammation, may serve as a feasible approach to enhance the odontogenic differentiation of stem/progenitor cells on a biomimetic scaffold for 3D dentin regeneration. These results present a first step in the development of a dental tissue engineering strategy where odontogenesis is enhanced by modulating inflammation.