In vivo conversion of rat astrocytes into neuronal cells through neural stem cells in injured spinal cord with a single zinc-finger transcription factor

Abstract

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.

Dissecting the Dual Role of the Glial Scar and Scar-Forming Astrocytes in Spinal Cord Injury

“…This reduction of the glial scar led to improved axonal regeneration and functional recovery (Rodriguez et al, 2014;Hesp et al, 2018;Zarei-Kheirabadi et al, 2019). These studies may provide us with clues as to how to manipulate the glial scar; that is, to reduce its density modestly without interrupting its integrity.…”

“…Since irreversible neuronal loss is another primary problem in SCI recovery, cell reprogramming may solve this problem by converting other cell types into neurons. Previous studies showed that in vivo, astrocytes can be reprogrammed into functional neurons after SCI through a single transcription factor (Su et al, 2014;Zarei-Kheirabadi et al, 2019). These reprogramming strategies exhibit limited efficiency in transforming astrocytes, thereby avoiding excessive attenuation of the glial scar.…”

Astrocytic reprogramming combined with rehabilitation strategy improves recovery from spinal cord injury

“…Several previous studies have resulted in a moderate glial scar reduction, intentionally or unintentionally, which leads to functional recovery. [42][43][44] These results may provide us with a new idea about how to manipulate the glial scar, which is to attenuate the density of the scar moderately without interrupting its integrity. In this study, we show that the Sox2-induced astrocytic reprogramming strategy can attenuate the density of glial scars more moderately, slowly, progressively, and partially and has higher clinical feasibility than the other interventions mentioned above.…”

Overexpression of the transcription factors OCT4 and KLF4 improves motor function after spinal cord injury

“…Moreover, KLF4 might be a regulator of proliferation and migration in neurons, blood, kidneys, and skin cells 39 . Furthermore, Zarei‐Kheirabadi et al found that rat astrocytes were transdifferentiated into neural stem cells in vitro by ZFP521 or Sox2, and Wang et al confirmed that the p‐53 pathway could improve the reprogramming efficiency of the astrocytes to neuroblasts transition induced by Sox2 40,41 . In addition to these findings, the OCT4 and KLF4 TFs may be significant regulators of the biological behaviors of astrocytes by inducing cellular reprogramming.…”