Multimodal Nonlinear Optical Imaging of Cell-Matrix Interaction during Spinal Cord Injury Ex Vivo

Neurons within spinal cord injury (SCI) are prevented from regeneration because of scar formation. Chondroitinase ABC ( ChABC) was reported to promote functional recovery after spinal cord injury. However, the mechanism and the role of ChABC in the recovery are not clear. In this research, we used second harmonic generation (SHG) and two-photon excitation fluorescence (2PEF) images as probes to observe cell-matrix interaction on fibrosis after SCI followed by ChABC treatment. According to our experimental results, the enzyme ChABC could decrease cystic formation dramatically and consequently allow the spinal cord to regenerate. Using immunohistological analysis, we found that treatment with ChABC at the lesion area resulted in fewer chondroitin sulfate proteoglycans (CSPGs) remaining, longer axonal re- growth, and more new developmental neurons. Furthermore, ChABC 1 U/ml was more effective than 5 U/ml treatment. Using the noninvasive technology, SHG and 2PEF images, we could observe cell-matrix interaction clearly, not only in fixed samples but also in unfixed ex vivo samples. This technology presents a potential for clinical use in the near future