Background: Spinal cord injury (SCI) results in glial scar formation and irreversible neuronal loss, which finally leads to functional impairments and long-term disability. Our previous studies have demonstrated that the ectopic expression of Zfp521 reprograms fibroblasts and astrocytes into induced neural stem cells (iNSCs). However, it remains unclear whether treatment with Zfp521 also affects endogenous astrocytes, thus promoting further functional recovery following SCI. Methods: Rat astrocytes were transdifferentiated into neural stem cells in vitro by ZFP521 or Sox2. Then, ZFP521 was applied to the spinal cord injury site of a rat. Transduction, real-time PCR, immunohistofluorescence, and function assessments were performed at 6 weeks post-transduction to evaluate improvement and in vivo lineage reprogramming of astrocytes. Results: Here, we show that Zfp521 is more efficient in reprogramming cultured astrocytes compared with Sox2. In the injured spinal cord of an adult rat, resident astrocytes can be reprogrammed into neurons through a progenitor stage by Zfp521. Importantly, this treatment improves the functional abilities of the rats as evaluated by the Basso, Beattie, and Bresnahan (BBB) locomotor rating scale and further by calculation of its subscores. There was enhanced locomotor activity in the hind limbs, step length, toe spread, foot length, and paw area. In addition, motor evoked potential recordings demonstrated the functional integrity of the spinal cord. Conclusions: These results have indicated that the generation of iNSCs or neurons from endogenous astrocytes by in situ reprogramming might be a potential strategy for SCI repair.

Amputation of the proximal region in mammals is not followed by regeneration because blastema cells (BCs) and expression of regenerative genes, such as Msh homeobox () genes, are absent in this animal group. The lack of BCs and positional information in other cells is therefore the main obstacle to therapeutic approaches for limb regeneration. Hence, this study aimed to create blastema-like cells (BlCs) by overexpressing and genes in mouse bone marrow-derived mesenchymal stem cells (mBMSCs) to regenerate a proximally amputated digit tip. We transduced mBMSCs with and genes and compared osteogenic activity and expression levels of several -regulated genes (, , and keratin 14 ()) in BlC groups, including MSX1, MSX2, and MSX1/2 (in a 1:1 ratio) with those in mBMSCs and BCs and following injection into the amputation site. We found that gene overexpression increased expression of specific blastemal markers and enhanced the proliferation rate and osteogenesis of BlCs compared with mBMSCs and BCs via activation of and Histological analyses indicated full regrowth of digit tips in the-overexpressing groups, particularly in MSX1/2, through endochondral ossification 6 weeks post-injection. In contrast, mBMSCs and BCs formed abnormal bone and nail. Full digit tip was regenerated only in the MSX1/2 group and was related to boosted , and gene expression and to limb-patterning properties resulting from and overexpression. We propose that -transduced cells that can regenerate epithelial and mesenchymal tissues may potentially be utilized in limb regeneration.

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