STRO-1 selected rat dental pulp stem cells transfected with adenoviral-mediated human bone morphogenetic protein 2 gene show enhanced odontogenic differentiation

Dental pulp stem cells harbor great potential for tissue-engineering purposes. However, previous studies have shown variable results, and some have reported only limited osteogenic and odontogenic potential. Because bone morphogenetic proteins (BMPs) are well-established agents to induce bone and dentin formation, in this study STRO-1-selected rat dental pulp-derived stem cells were transfected with the adenoviral-mediated human BMP-2 gene. Subsequently, the cells were evaluated for their odontogenic differentiation ability in medium not containing dexamethasone or other stimuli. Cultures were investigated using light microscopy and scanning electron microscopy (SEM) and evaluated for cell proliferation, alkaline phosphatase (ALP) activity, and calcium content. Real-time polymerase chain reaction (PCR) was performed for gene expression of Alp, osteocalcin, collagen type I, bone sialoprotein, dentin sialophosphoprotein, and dentin matrix acidic phosphoprotein 1. Finally, an oligo-microarray was used to profile the expression of odontogenesis-related genes. Results of ALP activity, calcium content, and real-time PCR showed that only BMP2-transfected cells had the ability to differentiate into the odontoblast phenotype and to produce a calcified extracellular matrix. SEM and oligo-microarray confirmed these results. In contrast, the non-transfected cells represented a less differentiated cell phenotype. Based on our results, we concluded that the adenovirus can transfect STRO-1 selected cells with high efficacy. After BMP2 gene transfection, these cells had the ability to differentiate into odontoblast phenotype, even without the addition of odontogenic supplements to the medium.