Human Schwann-like Cells Derived from Adipose-derived Mesenchymal Stem Cells Rapidly De-differentiate in the Absence of Stimulating Medium

Finding a viable cell-based therapy to address peripheral nerve injury holds promise for enhancing the currently suboptimal microsurgical approaches to peripheral nerve repair. Autologous nerve grafting is the current gold standard for surgical repair of nerve gaps; however, this causes donor nerve morbidity in the patient, and the results remain unsatisfactory. Transplanting autologous Schwann cells (SCs) results in similar morbidity, as well as limited cell numbers and restricted potential for expansion in vitro. Adipose-derived stem cells (ASCs), 'differentiated' towards an SC-like phenotype in vitro (dASCs), have been presented as an alternative to SC therapies. The differentiation protocol stimulates ASCs to mimic the SC phenotype; however, the efficacy of dASCs in nerve repair is not yet convincing, and the practicality of the SC-like phenotype is unproven. Here, we examined the stability of dASCs by withdrawing differentiation medium for 72 h after the full 18-day differentiation protocol, and measuring changes in morphology, gene expression, and protein levels. Withdrawal of differentiation medium from dASCs resulted in a rapid reversion to stem cell-like characteristics. Quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent assay analyses demonstrated a significant reduction in gene and protein expression of growth factors that were expressed at high levels following 'differentiation'. Therefore, we question the relevance of differentiation to an SC-like phenotype, as withdrawal of differentiation medium, a model of transplantation into an injured nerve, results in rapid reversion of the dASC phenotype to stem cell-like characteristics. Further investigation into the differentiation process and the response of dASCs to an injured environment must be undertaken prior to the use of dASCs in peripheral nerve repair therapies.