Abstract: Objective: To explore the systemic immune response of mice after dental pulp stem cells (DPSCs) allogeneic transplantation. Methods: Dental pulp stem cells were isolated from C57BL/6 mice’s pulp, cultured to the third generation in vitro, and then cultured together with the nanometer hydroxyapatite into a composite. Scanning electron microscope was used to observe the growth condition of the composites. Forty C57BL/6 mice of four weeks were randomly divided into experimental group and control group. The experimental group mice were transplanted the composite under the skin of upper back. And the control group mice were transplanted nanometer hydroxyapatite under the skin of upper back. Two groups of animals were observed 4 and 6 weeks, respectively. The splenic cells of mice were prepared by a stainless steel mesh. Flow cytometry instrument was used to measure the value of CD4⁺ and CD8⁺. Results: Dental pulp stem cells were well bonded with nanometer hydroxyapatite in vitro. Immunohistochemical study showed that both 4 weeks and 6 weeks experimental groups had positive expressions of the dentin sialoprotein (DSP). After 4 and 6 weeks, the values of CD4⁺ and CD8⁺ had no obvious differences between the experimental group and the control group. Conclusion: The results of our experiments proved that after allogeneic transplantation of dental pulp stem cells, it is impossible to cause the body's immune rejection. Dental pulp stem cells still have low immunogenicity in vivo, which are expected to be a source of allograft tissue engineering seed cells in the future.

Key words: Dental, pulp, stem, cell, Allogenic, Transplant, In, vivo, Low, immunogenicity