CD146 positive human dental pulp stem cells promote regeneration of dentin/pulp-like structures

CD146 and STRO-1 are endothelial biomarkers that are co-expressed on the cellular membranes of blood vessels within human dental pulp tissue. This study characterized the percentage of dentin-like structures produced by CD146-positive (CD146⁺) human dental pulp stem cells (DPSCs), compared with their CD146-negative (CD146^-) counterparts. DPSC populations were enriched using magnetic-activated cell sorting (MACS), yielding CD146⁺ and CD146^- cells, as well as mixtures composed of 25% CD146⁺ cells and 75% CD146^- cells (CD146^+/-). Cell growth assays indicated that CD146⁺ cells exhibit an approximate 3-4 h difference in doubling time, compared with CD146^- cells. Cell cycle distributions were determined by flow cytometry analysis. The low percentage of CD146⁺ cells' DNA content in G₀/G₁ phase were compared with CD146^- and non-separated cells. In contrast to CD146^- and non-separated cells, prompt mineralization was observed in CD146⁺ cells. Subsequently, qRT-PCR revealed high mRNA expression of CD146 and Alkaline phosphatase in mineralization-induced CD146⁺ cells. CD146⁺ cells were also observed high adipogenic ability by Oil red O staining. Histological examinations revealed an increased area of dentin/pulp-like structures in transplanted CD146⁺ cells, compared with CD146^- and CD146^+/- cells. Immunohistochemical studies detected dentin matrix protein-1 (DMP1) and dentin sialophosphoprotein (DSPP), as well as human mitochondria, in transplanted DPSCs. Co-expression of CD146 and GFP indicated that CD146 was expressed in transplanted CD146⁺ cells. CD146⁺ cells may promote mineralization and generate dentin/pulp-like structures, suggesting a role in self-renewal of stem cells and dental pulp regenerative therapy.