Differentiation of MDSPCs to a neurogenic lineage prior to implantation decreases their ability to respond to environmental cues and stops transformation.

<p>(<b>A-C</b>) Two weeks post-implantation MDSPC-derived neurospheres showed a reduction in muscle regeneration when compared to the parental MDSPCs. (<b>A</b>) The <i>nLacZ</i> donor-derived MDSPC-derived neurospheres (blue) could be detected in eosin stained regenerated myofibers and (<b>B</b>) showed fewer regenerated dystrophin-positive myofibers (red) compared to undifferentiated MDSPCs. (C) Graphical representation of the regeneration index (number of dystrophin positive fibers/100,000 injected cells) of parental MDSPCs and MDSPC-derived neurospheres (NS). NS-injected mice yield a lower regeneration index compared to the undifferentiated MDSPCs. Error bars indicate ± s.d. (**<i>P</i><0.001, Mann-Whitney Rank Sum Test). (<b>D-F</b>) When dissociated MDSPC-derived neurospheres were implanted into a sciatic nerve defect, tumor formation was abrogated. Furthermore, 80% of mice (<i>n</i> = 5) formed large fibrotic masses, as seen by (<b>D</b>) eosin staining with <i>nLacZ</i> donor MDSPC-derived neurospheres shown in blue, in addition to (<b>E</b>) intense collagen deposits identified with Masson’s Trichrome staining (blue). (<b>F</b>) Graphical representation of the Trichrome-positive area of parental MDSPCs and NS. Parental MDSPCs show minimal signs of fibrosis evident by a lower percentage of collagen-positive area. Error bars indicate ± s.d. (**<i>P</i><0.001, Mann-Whitney Rank Sum Test). (<b>G</b>) A schematic of the experimental design and results. Scale bars represent 10 µm.