Therapeutics Effects of Oral Cavity Derived Stem Cells on the Neurodegenerative Diseases: A Systematic Review

Objective: Published data obtained from in vitro and in vivo studies was reviewed systematically and analyzed critically in order to evaluate the effect of oral cavity derived stem cells (OCDSCs) on the recovery/therapy of neurodegenerative diseases (NDs) such as Alzheimer’s (AD), Amyotrophic Lateral Sclerosis (ALS), Huntington’s (HD) and Parkinson’s (PD). Methods: An electronic search was accomplished. References of included articles were also searched manually. Studies were critically evaluated for suitability against inclusion/exclusion criteria and data was extracted. Bias risk evaluation of the studies and evidence synthesis were conducted. Results: Fourteen in vivo and 10 in vitro studies met inclusion criteria. PD was induced in 10 in vivo and 7 in vitro studies, while AD was induced in 2 in vivo and 4 in vitro studies. Two studies (1 in vitro and 1 in vivo) evaluated ALS disease and 1 in vivo study evaluated HD. Moderate evidence was found for in vitro studies reporting positive effect of OCDSCs on either PD or AD recovery. Strong evidence was found for in vivo studies in which PD animal models were used; while moderate evidence was found for the impact of OCDSCs on the recovery of the AD. Limited evidence was found for in vivo studies evaluating HD and ALS. Conclusion: Although studies included reported favorable data regarding the OCDSCs on NDs, they presented considerable risk of bias. Because of heterogenous study characteristics, current study recommends the improvement of standardized methods to evaluate the therapeutics effects of OCDSCs on the NDs.