Development of a Novel Large Animal Model to Evaluate Human Dental Pulp Stem Cells for Articular Cartilage Treatment.

PURPOSE: Chondral lesion is a pathology with high prevalence, reaching as much as 63% of general population and 36% among athletes. The ability of human Dental Pulp Stem Cells (DPSCs) to differentiate into chondroblasts in vitro suggests that this stem cell type may be useful for tissue bioengineering. However, we have yet to identify a study of large animal models in which DPSCs were used to repair articular cartilage. Therefore, this study aimed to describe a novel treatment for cartilage lesion with DPSCs on a large animal model. METHODS: Mesenchymal stem cells (MSC) were obtained from deciduous teeth and characterized by flow cytometry. DPSCs were cultured and added to a collagen type I/III biomaterial composite scaffold. Brazilian miniature pig (BR-1) was used. A 6-mm diameter, full-thickness chondral defect was created in each posterior medial condyle. The defects were covered with scaffold alone or scaffold + DPSCs on the contralateral side. Animals were euthanized 6 weeks post-surgery. Cartilage defects were analyzed macroscopically and histology according to modified O'Driscoll scoring system. RESULTS: Flow cytometry confirmed characterization of DPSCs as MSCs. Macroscopic and histological findings suggested that this time period was reasonable for evaluating cartilage repair. To our knowledge, this study provides the first description of an animal model using DPSCs to study the differentiation of hyaline articular cartilage in vivo. CONCLUSION: The animals tolerated the procedure well and did not show clinical or histological rejection of the DPSCs, reinforcing the feasibility of this descriptive miniature pig model for pre-clinical studies.

Immature bovine oocyte cryopreservation: comparison of different associations with ethylene glycol, glycerol and dimethylsulfoxide.

Research on different cryoprotectants and their associations is important for successful vitrification, since greater cryoprotectant concentration of vitrification solution may be toxic to oocytes. The aim of the present research was to compare the efficiency of immature bovine oocyte vitrification in different associations of ethylene glycol (EG), glycerol and dimethylsulfoxide (Me(2)SO). In the first experiment, oocytes were exposed to the cryoprotectant for either 30 or 60s in final solutions of EG+DMSO1 (20% EG+20% Me(2)SO) or EG+DMSO2 (25% EG+25% Me(2)SO) or EG+GLY (25% EG+25% glycerol). In the second experiment, the oocytes were vitrified in open pulled straws (OPS) using 30s exposure of final solutions of EG+DMSO1 or EG+DMSO2 or EG+GLY. Maturation rates of 30s exposure groups were not different from the control, but 60s cryoprotectant exposure was toxic, decreasing maturation rates. The vitrification with EG+DMSO2 resulted in enhanced maturation rate (29.2%) as compared with EG+DMSO1 (11.7%) and EG+GLY (4.3%) treatments. These data demonstrate that concentration and type of cryoprotectant have important effects on the developmental competence of vitrified oocytes.