Study On Repair Mechanism Of Rat Spinal Cord Injury By Implantation Of Chemically Extracted Acellular Muscle Scaffold Seeded With Amniotic Epithelial Cells

Spinal cord injury often leads to permanent neurological deficits, and its treatment has always been a medical problem in the world. Glial scar formation after spinal cord injury is usually difficult to overcome by gene therapy and cell transplantation strategies but it can be replaced by nerve tissue engineering scaffolds which form an important part in the treatment of spinal cord injury. Previously, our research group found that acellular muscle tissue engineering scaffolds alone or combined with amniotic epithelial cells can effectively promote axonal regeneration of injured spinal cord, and that specific mechanism for treatment is not clear. In this study, we explored on repair mechanisms in the treatment strategy for the promotion of axon regeneration in rat thoracic spinal cord hemisection.First of all, we have studied the repair mechanisms of acellular muscle tissue engineering scaffold promoting the axonal regeneration in spinal cord injury. We made rat spinal cord hemisected injury models as well as the chemically acellular muscle scaffold and implanted the scaffold into the rat spinal cord injury. One week after operation, we observed the distribution of adhesion molecules associated with axonal regeneration in acellular muscle scaffold before and after implantation.7days after implantation, the results of immunohistochemistry showed a significant increase in the amount of laminin and fibronectin than before implantation. In addition, we also found that the acellular muscle is conducive to immigration of other axonal regenerating related molecular and cellular components, such as the neural cell adhesion molecule (N-CAM) and S100-positive cells. The experimental results showed that the scaffolds were infiltrated by numerous host cells. The above results suggested that chemically extracted acellular muscle scaffold undergoes a remodeling process when implanted into the spinal cord. The remodeling of the chemically acellular muscle establishes an environment that is helpful to axonal regeneration after spinal cord injury.After that, we did further research on the therapeutic mechanism of chemically acellular muscles with amniotic epithelial cells after implantation into injured rat spinal cord. Chemically acellular muscles, with or without amniotic epithelial cells, were implanted into lateral hemisected adult rat thoracic spinal cord. Control rats were similarly injured.7days after transplantation, the expression and distribution of BDNF and NT-3have been observed in the AECs-acellular muscles graft. And both the chemically acellular muscle group and injured control groups were lacking the distribution of these two proteins in scaffold area or injured area, suggesting that amniotic epithelial cells performed a neurotrophic function after transplantation. The expression of TrkB and TrkC in the area surrounding the scaffolds increased when implanted chemically acellular muscles alone or AECs-acellular muscle grafts, and no positive results were seen in control group, suggesting that the implantation of graft helps to maintain the reactivity of spinal cord tissue to neurotrophic factors. The combination of amniotic epithelial cells promotes the regeneration of myelinated nerve fibers. The above data suggest that the amniotic epithelial cells mainly promote functional recovery of injured spinal cord through its neurotrophic function.Our study establishes some aspects of the mechanism of acellular muscle tissue engineering scaffolds alone or combined with amniotic epithelial cells for the repair of rat spinal cord injury. This may provide more information for the basis of spinal cord injury repair.