EXPLORING THE ROLE OF PERIPHERAL MYELIN PROTEIN 22 EXPRESSION IN ORDERED MEMBRANE DOMAINS OF SCHWANN CELL DIFFERENTIATED DENTAL PULP STEM CELLS AND HOW IT AFFECTS CELL-MATRIX INTERACTIONS

Abstract

New therapeutic strategies to establish repair of injured peripheral nerves are desperately needed. For this purpose, our group developed Engineered Neural Tissue with Schwann cell differentiated human dental pulp stem cells (SC-hDPSC) embedded in an aligned collagen hydrogel 1, 2. The use of SC-DPSCs as a cell source for nerve repair has several advantages but there is a need to better understand how they interact with the extracellular matrix (ECM) and how this affects their myelinating behavior. We aim to investigate the role of peripheral myelin protein 22 (PMP22) in the interaction of SC-hDPSCs with an endoneurial-like ECM. SC-hDPSC were cultured on 2D coated surfaces and by performing immunostainings combined with confocal-and super resolution STORM microscopy we showed that PMP22 is expressed in lipid rafts of the plasma membrane. Live cell/TIRF imaging experiments with cholera toxin b showed that these lipid rafts are highly dynamic. We also observed a strong colocalization between PMP22 and integrin b1, a6, and b4 in the membrane of SC-hDPSC. In addition, SC DPSC cultured in aligned or free floating hydrogels strongly interact with collagen I fibres via these integrins, which was confirmed macro-scopically and with label-free second harmonic generation microscopy. In conclusion, we showed that PMP22 is expressed in ordered regions in the SC-hDPSC membrane together with integrins that are important for cell interactions with the ECM and in myelination. This implicates that PMP22 may play a role in controlling myelination, but this will be explored in future experiments.