Xeno- and transgene-free reprogramming of mesenchymal stem cells toward the cells expressing neural markers using exosome treatments

Abstract

Neural stem cells (NSCs), capable of self-renew and differentiate into neural cells, hold promise for use in studies and treatments for neurological diseases. However, current approaches to obtain NSCs from a live brain are risky and invasive, since NSCs reside in the subventricular zone and the in the hippocampus dentate gyrus. Alternatively, mesenchymal stem cells (MSCs) could be a more available cell source due to their abundance in tissues and easier to access. However, MSCs are committed to producing mesenchymal tissue and are not capable of spontaneously differentiating into neural cells. Thus, the process of reprogramming of MSCs into neural cells to use in clinical and scientific settings has significantly impacted the advancement of regenerative medicine. Previously, our laboratory reported trans-differentiation of MSCs to neural cells through the induced pluripotent stem (iPS) cells state, which was produced by overexpression of the embryonic stem cell gene NANOG. In the current study, we demonstrate that treatment with exosomes derived from NSCs makes MSCs capable of expressing neural cell markers bypassing the generation of iPS cells. An epigenetic modifier, decitabine (5-aza-2'-deoxycytidine), enhanced the process. This novel Xeno and transgene-free trans-differentiation technology eliminates the issues associated with iPS cells, such as tumorigenesis. Thus, it may accelerate the development of neurodegenerative therapies and in vitro neurological disorder models for personalized medicine.

Direct Reprogramming of Somatic Cells to Neurons: Pros and Cons of Chemical Approach

“…However, due to their low efficiency, transgene silencing, inflammation and poor nuclear uptake, are less commonly used in transdifferentiation studies [ 45 ]. Lately, the use of neural exosomes [ 46 ] and the protein transduction domains (PTDs) fused to TFs allow the direct delivery of exogenous TFs avoiding the problems associated with DNA integration into the host genome [ 47 ] opening up new strategies for possible clinical applications.…”

Recent Developments in Surface Topography-Modulated Neurogenesis

“…Generally, MSCs are capable of differentiating into mesodermal cell types such as osteoblast, chondrocytes or myocytes [47]. However, lineage reprogramming aka transdifferentiating MSCs into neuron-like cells is possible and has been proven by multiple studies [48]. Neurogenesis markers β3 tubulin and MAP2 expression was reported to increase when bone marrow-derived human mesenchymal stem cells were cultured on soft vs stiff hydrogels, indicating the susceptibility of the cells to the biophysical properties of the extracellular matrix (ECM) [49].…”