Gelatin methacryloyl hydrogel with and without dental pulp stem cells for TMJ regeneration: An in vivo study in rabbits

Background In the last decade, tissue‐engineering strategies for regenerating the temporomandibular joint (TMJ) have been investigated. This may be a promising strategy for the minimally invasive restoration of joint integrity. Objectives To evaluate whether dental pulp stem cells (DPSCs) loaded in a light‐occured hydrogel made of gelatin methacryloyl (GelMA) enhance the regeneration of osteochondral defects in the rabbit TMJ. Materials and Methods Defects were filled with GelMA alone (control group; n = 4) or filled with GelMA loaded with rabbit DPSCs (experimental group; n = 4), In one group, the TMJ capsule was opened without creating a defect (sham group; n = 2). The following micro‐CT parameters were analysed: bone volume to total volume ratio (BV/TV%) and bone mineral density (BMD). Histological evaluation was performed to assess cartilage regeneration features. A semi‐quantitative scoring system was also used to evaluate the defects. Results All groups had no statistical difference regarding the micro‐CT parameters. The highest mean healing score was found for the experimental group. After 4 weeks, there were no signs of hydrogel in either group or no signs of inflammation in the adjacent tissues. The tissue formed in the defect was dense fibrous connective tissue. Conclusion Adding DPSCs to GelMA did not provide a regenerative enhancement in TMJ osteochondral defects. This resulted in similar micro‐CT parameters after 4 weeks of healing, with improved signs of subchondral bone regeneration but no cartilage regeneration. Osteochondral defects were created in the TMJ condyles of rabbits, and subsequently, a light‐cured hydrogel loaded with dental pulp stem cells was introduced into these defects. The addition of gelatin methacryloyl hydrogel with dental pulp stem cells to these defects enhances micro‐CT parameters associated with subchondral bone healing. However, it does not lead to the restoration of cartilage after one month of implantation.