Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.19.210633v1?rss=1 Authors: Challagundla, N., Rajput, R. A. Abstract: Development is an irreversible process of differentiating the undifferentiated cells to functional cells. Brain development involves generation of cells with varied phenotype and functions, which is limited during adulthood, stress, damage/degeneration. Cellular reprogramming makes differentiation reversible process with reprogramming somatic/stem cells to alternative fate with/without stem cells. Exogenously expressed transcription factors or small molecule inhibitors have driven reprogramming of stem/somatic cells to neurons providing alternative approach for pre-clinical/clinical testing and therapeutics. Here in, we report a novel approach of microRNA (miR)-induced trans-differentiation of macrophages (CD11b high) to induced neuronal cells (iNCs) (neuronal markers high-Nestin, Nurr1, Map2, NSE, Tubb3 and Mash1) without exogenous use of transcription factors. miR 9, 124, 155 and 224 successfully transdifferentiated macrophages to neurons with transient stem cell-like phenotype. We report trans differentiation efficacy 18% and 21% with miR 124 and miR 155. in silico (String 10.0, miR gator, mESAdb, TargetScan 7.0) and experimental analysis indicate that the reprogramming involves alteration of pluripotency genes like Oct4, Sox2, Klf4, Nanog and pluripotency miR, miR 302. iNCs also shifted to G0 phase indicating manipulation of cell cycle by these miRs. Further, CD133+ intermediate cells obtained during current protocol could be differentiated to iNCs using miRs. The syanpsin+ neurons were functionally active and displayed intracellular Ca+2 evoke on activation. miRs could also transdifferentiate bone marrow-derived macrophages and peripheral blood mononuclear cells to neuronal cells. The current protocol could be employed for direct in vivo reprogramming of macrophages to neurons without teratoma formation for transplantation and clinical studies. HighlightsO_LImiR 9, miR 124 and miR155 could reprogramme macrophages to mature neurons. C_LIO_LImiR-induced neuronal reprogramming involves stem cell like intermediate phenotype. C_LI Graphical Abstract O_FIG_DISPLAY_L [Figure 1] M_FIG_DISPLAY Macrophages transfected with miR 9, 124, 155 and 224 alter pluripotency genes and neuronal differentiation genes via various mechanisms as elucidated. NIM components may also manipulate driving neuronal differentiation gene expression inducing formation of neuronal cells. C_FIG_DISPLAY Copy rights belong to original authors. Visit the link for more info