Establishment and examination of an inducible bone morphogenetic protein 7 (BMP-7) expressing dental pulp stem cell line

Abstract

Dental pulp stem cells (DPSC) from extracted adult teeth are multipotent cells which are capable of differentiation into
various connective-tissue cell lineages, including osteoblasts and odontoblasts. DPSC can be safely cryopreserved, and easily maintained in cell cultures, therefore, their use as a donor in tissue engineering and regeneration procedures is an attractive alternative. The BMP-7 protein is member of the transformation growth factor (TGF)-β superfamily of growth factors, known to act as an inducer of osteoblast differentiation in vitro and in vivo. Human recombinant BMP-7 is already used in the fusion of vertebral bodies, and in the treatment of tibial non-union under the brand name OP-1. The aim of this work was the establishment of an inducible BMP-7 expressing cell line. To generate an efficient and regulated transgene expression, we utilized a second generation lentiviral tet-on gene expression system to modulate BMP-7 expression. It was demonstrated, that the cell line is capable of induced BMP-7 expression, the expression of which is doxycyclin dose-dependent, and can be aborted upon cessation of doxycycline treatment. The leakage of the system in the absence of doxycycline is negligible. We intend to use this cell line to investigate the effect of inducible BMP-7 gene expression on the osteogenic differentiation of DPSC, a potent donor cell line in tissue engineering.