Regeneration of temporomandibular joint using in vitro human stem cells: A review

Temporomandibular joint disorders (TMDs) range from gross anatomic deformities of the disc and hard tissue to functional disturbances. Traditional treatment of TMDs includes physical therapy, use of appliances, pharmacological, surgical and psychological interventions. However, during the late stage of TMDs, conventional management often results in inadequate relief of symptoms. Stem cell-based tissue regeneration has been studied extensively in joint regeneration, including the Temporomandibular Joint (TMJ). This study aims to review the potential of various human stem cells (HSC) for the regeneration of the TMJ. In vitro studies using human mesenchymal stem cells cultured under different conditions to evaluate regeneration of TMJ related structures were searched on PubMed, EMBASE, Cochrane, and Web of Science up to March 2020. In vitro studies utilized several different types of stem cells under varying conditions. Increased osteogenesis and/or chondrogenesis were noted with stem cell interventions compared to control groups on Alkaline Phosphatase (ALP) activity, Col-I, Col-II, Col-X, RUNX2, LPL, and Aggrecan mRNA expression. This review emphasizes the potential of stem cell therapies in the regeneration of TMJ-related structures. However, further in vivo studies are required to evaluate the efficacy and safety of these therapies in humans.