Using Three-dimensional Root End Tooth Papilla Regeneration Complex Pulp Tissue Stem Cell Aggregates And Dentin Matrix Fragments

Dental pulp is a soft connective tissue and its main functions are to produce dentin, and maintain the biological and physiological vitality of the dentin. When infected by mechanical trauma, chemical irritation or microbial invasion, it is difficult to eradicate the infection by autoimmune system owing to the lack of a collateral blood supply. Clinically, when pulp is diagnosed with irreversible pulpitis, no treatment can reverse the situation regardless of the amount of remaining normal pulp tissue, the entire pulp is amputated by endodontic therapy. However, loss of abilities of nutrition, repair and defense in these teeth affects on the life span of teeth. Therefore, treatment with vital pulp is a promising strategy.The regeneration of dental pulp/dentin-like tissues has been a spot in oral medical research in the nation and world. Recently, cell-based treatments based on tissue engineering techniques have advanced on different fields. And cells, microenvironment and scaffold is three key factors for the construction and regeneration of tissue engineering organ. Currently, some researches on dental pulp/dentin tissue regeneration have been reported, but the regeneration of integrated dental pulp/dentin-like tissues with accessing to normal length of dental root and continuous mineral capability has not been completed. Its main reason is shortage of promising cells, microenvironment and scaffold.Above all, the study is to investigate promising cells, to construct a novel three dimensional stem cell mass and to regenerate dental pulp/dentin-like tissues.Main results:PartⅠ. Promising cellTo select optimizing stem cells for regenerating dental pulp/dentin-like tissues, we tested DPSCs and SCAP biological characteristics. Results show SCAP is higher abilities of proliferation and differentiation than DPSCs and thus SCAP is promising cells for regeneration of dental pulp/dentin-like tissues.PartⅡ. Construction of a novel three-dimensional stem cell mass without any scaffolds.To find promising cell mass without scaffold, we compared cell mass with cell sheet and improved and tested cell mass biological characteristics. Results show that cell mass includes a large number of extracellular matrix (ECM) and enough cell number。In addition, cells on the surface of cell mass expanded adequately and connected closely. In the level of gene, we found that cell mass has higher ability of osteo/odontogenesis than cell sheet. Therefore, cell mass is better for regeneration of dental pulp/dentin-like tissues.PartⅢ. Regeneration of dental pulp/dentin-like tissuesDr. Guo WH in our lab tested systematically dentin matrix dissolved by EDTA and found that it not only play a role in supporting cells, but also providing a microenvironment for odontogenesis. Therefore, SCAP cell mass is inserted into root cancel dissolved by EDTA, and then implanted into the subcutaneous space on the back of immunodeficient mice. Six weeks after the transplantation, the mice were euthanized and tooth fragments removed for histological analysis. We found a vascularized dental pulp-like tissue, a continuous layer of dentin-like tissue. In addition, the cells lining against the dentin-like tissue were positive staining for DSP, BSP, ALP and human mitochondria.