For example, a modified methylcellulose hydrogel was recently developed as an affinity-based system that sustained the release of bioactive ChABC for at least 7 days [283], although it has not yet been tested in culture or in vivo. Electrospun collagen nanofibres have been developed to codeliver neurotrophin-3 and ChABC (also incorporating heparin) and offer sustained release in vitro for 4 weeks [284]. In vivo, a high concentration fibrin gel was found to retain nearly six times more bioactive ChABC in the injury site 3 weeks after spinal cord injury [285]. Thus, attempts to optimize and sustain delivery of ChABC look

promising for the future development of this therapy towards use in the clinic. The first study to show that the upregulation of CSPGs could be ameliorated by ChABC application following Crizotinib datasheet spinal contusion also observed deposition Pexidartinib of CSPGs around transplanted foetal cell grafts [242]. Various transplant

approaches aim to create a favourable environment conducive to axon regeneration in the spinal cord. This includes peripheral nerve grafts (PNGs) [286] intraspinal transplantation of foetal spinal cord tissue [287] and cellular transplants such as olfactory ensheathing cells [288], Schwann cells [289], cells transfected to secrete growth factors [290,291] and stem cell populations (such as embryonic stem cells, neural progenitor cells, bone marrow mesenchymal cells) [292–294]. Robust axon entry into these environments is often associated with stalled exit at the transplant/CNS interface or, at best, reduced growth into the CNS environment, thought to be at least partly due to the presence of CSPGs at the graft/host interface [160]. Administration of ChABC in combination with PNG transplantation has been shown to promote additional benefit than PNG grafting alone. For example, implantation of a PNG combined with BDNF did not stimulate regeneration following spinal cord hemisection; however, ChABC-mediated degradation of CS-GAGs promoted

regeneration of Clarke’s nucleus neurones into the graft [295]. Modulation of ECM CSPGs using ChABC after cervical hemisection has also been found to promote significant axonal regeneration beyond the distal end of a PNG back into the spinal cord to promote motor recovery Tyrosine-protein kinase BLK [296,297] and functional regeneration of respiratory pathways to the paralysed diaphragm [298]. Furthermore, following complete thoracic transection, ChABC application alongside a transplanted PNG resulted in impressive regeneration to restore supraspinal control of bladder function [299]. It has been reported that CSPGs in both acute and chronic SCI negatively influence the migration, long-term survival and integration of transplanted neural precursor cells and therefore their therapeutic potential for promoting functional repair and plasticity. This is a problem significantly reduced by ChABC pre-application to the transplant site [300,301].