Towards remyelination therapy with fate-committed Schwann cells derived from bone marrow stromal cells in vitro

Abstract

The main goal of the research project is to promote post-traumatic nerve regeneration in human Central & Peripheral Nervous System (CNS & PNS) employing autologous Schwann Cells derived from adult tissues in nerve guidance channels on developed ground. The research focus is to employ Human Induced Pluripotent stem cell (IPSC) and Bone Marrow Stromal Cell (BMSC)-derived neurons, as a human alternative to rat dorsal root ganglion (DRG) neurons, to achieve fate commitment of Schwann cells sourced from bone Marrow Stromal Cells (BMSCs) through coculturing. The purpose and major concerns of such choice is to pioneer and optimize the current options in terms of safety, simplicity and efficiency for prospects of spinal cord injury treatment strategy. We hypothesis that derived neurons sourced from IPSCs and BMSCs contain Notch ligands for the sequential activation of Notch, Juxtacrine (contact-mediated) and ErbB signaling pathways upon coculture with SCLCs, which would contribute to Schwann cell fate commitment, securing its acquired phenotype and functional capacity. Coculture of human sensory neurons with SCLCs under myelinating conditions are hypothesized to supply critical ligands Jagged-1 and DLL-1 of the Notch signaling pathway, resulting in upregulated levels of neuronal neuregulin 1 type III in conjunction with the phosphorylated receptors ErbB2 and ErbB3, which in turn stimulate SCLCs to achieve fate commitment for later axonal ensheathment and myelination. In the study, human BMSCs have been successfully differentiated into SCLCs through neurosphere formation. Mature small-molecules induced sensory neurons have also been generated from Induced Pluripotent Stem Cells (IPSCs), though unfortunately, the cells experience arrest and death after completing maturation culture. Human Neural Progenitor Cells (NPCs) derived express the Notch Ligand Jagged-1 and EGF receptor ligand Nrg1 type III earliest on Day 8, upon completion of induction, and express the sensory neuron marker BRN3A on Day12. This suggests the early appearance of functional capacity of generated NPCs, even before achieving fate commitment as sensory neurons. Yet, the generated neurons still lack sustainability, which poses problem for SCLC-coculture; a problem to be addressed in later studies. The study has provided prospects on a feasible human alternative for solving the fate commitment dilemma of cultured human Schwann cells for remyelination therapies, which require further in vivo experiments to pave way for final application in human patients.