Dental Pulp Stem Cells: a Promising CMT1A in Vitro Model

Objectives: Charcot-Marie-Tooth disease type 1A (CMT1A) is the most common demyelinating peripheral neuropathy, caused by a duplication of the peripheral myelin protein 22 (PMP22) gene. It is mainly expressed by Schwann cells, where it plays an essential role in developing, maintaining, and stabilizing healthy myelin. The use of autologous primary human Schwann cells is restricted, and animal models are often of limited translational value. Therefore, there is no cure for CMT1A. We aim to develop a human dental pulp stem cell (DPSC)-based in vitro model to study CMT1A-related disease mechanisms. DPSC are isolated from the dental pulp of third molars and can be classified as a subtype of mesenchymal stem cells (MSC).
Methods: Multiple healthy donor-derived DPSC lines were differentiated towards Schwann cells (DPSC-SC), and donor-based variability was determined through qPCR and immunocytochemistry (ICC). Next, we used lentiviral vectors to induce PMP22 overexpression in the DPSC-SC to mimic CMT1A.
Results: After DPSC differentiation, Schwann cell markers P75NTR, S100B, SOX10, Laminin211, and Laminin411 showed stable and similar expression in DPSC-SC from different donor lines. Furthermore, following lentiviral transduction, mRNA levels confirmed successful PMP22 overexpression in the DPSC (150%, p=0.1609). By diluting the lentiviral vector titer to the extent that only 10% of the cells were transduced, we obtained DPSC and DPSC-SC that overexpress only one extra copy of the PMP22 gene, mimicking the PMP22 duplication in CMT1A.
Conclusions: In conclusion, our data confirm a high consistency in our Schwann cell differentiation protocol. Additionally, we successfully induced PMP22 overexpression in both DPSC and DPSC-SC. Alternative approaches for PMP22 overexpression, such as CRISPR/Cas9, may provide an alternative approach. Further research should focus on validating this novel human in vitro CMT1A model.