A Study on the Effect of Human Dental Pulp Stem Cell Conditioned Medium on Human Oral Squamous Cell Carcinoma Cell Lines

In recent years, the application of conditioned medium (CM) in regenerative medicine has received much attention. However, the incidence of cancer in Japan is continuing to rise, with one in two people having cancer, among those who may be candidates for CM treatment and may be affected by or have a risk of cancer. We investigated the effects of human dental pulp stem cell (DPSC)-derived CM on human oral squamous cell carcinoma (OSCC) cell lines. CM was extracted from DPSC isolated from human dental pulp, and cell proliferation rates upon contact with OSCC cell lines were compared. Furthermore, chemosensitivity was evaluated with the collagen gel droplet embedded culture drug sensitivity test and was compared using Dulbecco's modified Eagle's medium (DMEM). To test the effect of DPSC-CM on xenograft tumors, an in vivo comparative study was conducted to investigate the tumor proliferation rate upon DPSC-CM and DMEM administration in tumor-bearing nude mice. The tumor growth factor production in culture medium over time was measured with enzyme-linked immunosorbent assay (ELISA) and was compared using DMEM. Vascular endothelial growth factor (VEGF) level significantly increased in the DPSC-CM contact group with ELISA. Therefore, VEGF-A-mRNA expression in the OSCC cell line was studied with real-time polymerase chain reaction for comparison. No significant differences were observed in the cell proliferation rate or drug sensitivity between different culture media in each cell line or in in vivo tumor proliferation rate. However, VEGF level contained in the cultured medium was significantly higher than that in the DPSC-CM group. VEGF-A-mRNA level in OSCC cell lines was significantly higher in the DPSC-CM group, which increased over time. These results suggested that exposure to DPSC-CM does not immediately affect tumor growth or drug resistance, but induces VEGF overexpression in tumor cells.