Fabrication and Characterization of a Protein Composite Conduit for Neural Regeneration

Spinal cord injury (SCI) causes the proliferation of resident microglia and promotes cell migration. Peripheral nerve injury induces the morphological changes and proliferation macrophages. The implantation of neural conduits has been investigated for the repair of wounded spinal cords and peripheral nerves. However, the tissue reaction of microglia and macrophages to implanted materials may enhance the immunological response and therefore aggravate the neural injury. There is a critical need to optimize the neural conduit to improve the therapeutic effect. Collagen is a major component of the extracellular matrix, and it has specific advantages to generating biomaterial scaffolds. Soy protein has tunable structural and mechanical properties and an anti-inflammatory function. In this study, a soybean protein isolate (SPI) and collagen (SPI-collagen) composite was used to fabricate a multichannel conduit that was cross-linked with (1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide (EDC). A number of material and mechanical tests were performed to characterize the conduits. The proliferation rate of human microglial clone 3 cell line (HMC3) cells and human induced pluripotent stem (iPS) cell-derived neural stem cells (i-HNSC) grown on SPI-collagen scaffolds was lower than that of the collagen scaffolds. Hippocampal neurons and i-HNSC-derived neurons showed extensive neurite growth on the SPI-collagen scaffolds. The motility of HMC3 cells and i-HNSCs on SPI-collagen scaffolds was studied using time-lapse microscopy. These studies suggest that the SPI-collagen conduit can potentially be used as an implantable scaffold and enhance the regeneration of wounded nerves and spinal cords.