Chemically extracted acellular muscle: a new potential scaffold for spinal cord injury repair

Extracellular matrix is the gold standard for tissue regeneration. In this study, we directly made the extracellular matrix of the tissue or organ into scaffold for spinal cord injuries, a strategy that is seldomly tried in spinal cord engineering. The aim of this study was to determine if the chemically extracted acellular muscle could be a potential scaffold for spinal cord injury. The chemically extracted acellular muscle was implanted in the lateral hemisected adult rat thoracic spinal cord. Control rats were similarly injured. After 1 and 4 weeks, scaffold integration and biocompatibility, axon sprouting, and myelination were evaluated. The chemically extracted acellular muscle scaffolds were found to be well integrated with the host tissue. Sprouting axons grew into the full length of the scaffold in a strikingly parallel and linear fashion. A few remyelinated axons were also detected in the scaffolds. The tracing results in another six rats showed that labeled fibers entered the chemically treated muscle grafts. Furthermore, there were no apparent quantitative differences in the ED-1 and glial fibrillary acidic protein positive cells between groups. Neuron counting showed more surviving neurons in the acellular muscle treated group than those of the injured only group. Vascularization of the grafts was also confirmed. These findings clearly demonstrated that chemically extracted acellular muscle grafts provided useful biomatrices to enhance axon sprouting in the injured spinal cord.