Our previous research has shown that seeding amniotic epithelial cells (AECs) in chemically extracted acellular muscle scaffold (CEAMC) better promotes the functional recovery of spinal cord injury (SCI) than scaffold alone. However, the massive death of transplanted cells, which is related to early inflammatory response, is still a problem in cell therapy. Our previous study proved that nordihydroguaiaretic acid (NDGA) inhibits inflammation after SCI. In this study, we tested a strategy of combining the early administration of NDGA and the transplantation of AEC-seeded CEAMC to treat SCI. The results showed that simply increasing the number of surviving AECs had no significant benefits in SCI therapy, but NDGA administration ameliorated transplanted AEC survival demonstrating the potential value of NDGA in the cellular transplantation treatment of SCI.

Objective To explore the intrinsic mechanism of the mammalian target of rapamycin (mTOR) pathway activation and promotion of neuronal axon growth. Methods Human neuroblastoma cells, SH-SY5Y, were induced with all-trans retinoic acid (ATRA; 10 μM for three days) which differentiated the cell line into a neuronal-like state. Immunohistochemical staining was used to detect the differentiation status of the neuronal-like cells. Phosphatase and tensin homolog (PTEN) RNA interference (RNAi) experiments were performed on the differentiated cells; reverse transcription-polymerase chain reaction (RT-PCR) detected transcriptional levels of PTEN following 24 h of interference. After 36 h, western blot assay was used to detect expression levels of ribosomal protein S6 kinase (pS6k) and mTOR. To downregulate the expression of PTEN and cluster of differentiation 44 (CD44), a cell-surface glycoprotein, simultaneously, PTEN siRNA and CD44 siRNA sequences were mixed in equal proportions in co-interference experiments. RT-PCR detected the transcription level of CD44, and the relationship between the CD44 and axonal growth was observed after 48 h of interference. Results Microtubule-associated protein 2 (MAP2) expression was enhanced after three days of induction in SH-SY5Y cells. RT-PCR showed the transcription level of PTEN was significantly downregulated after 24 h of PTEN knockdown. mTOR and pS6k protein expression levels were significantly upregulated after 36 h of interference. CD44 transcription levels were upregulated after PTEN gene interference. The neurite length of the cells in the experimental interference group was significantly longer than that in the control group, and the expression level of CD44 was positively correlated with neurite growth. The neurite length of the PTEN-only interference group was significantly greater than that of the co-interference and ATRA groups. Conclusion Activation of the mTOR pathway promoted neurite growth through upregulation of CD44 expression, thus promoting neuronal regeneration.

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