It is a widely accepted fact in the scientific community that the central nervous system (CNS) is generally incapable of regeneration following an injury. Individuals living with spinal cord injuries (SCIs) and traumatic brain injuries (TBIs) face much lower life expectancies and qualities of life than those without CNS damage. For this reason, one of the most prominent areas of recent neuroscientific research has been determining how to promote regeneration and repair in the brain and spinal cord by exogenous means, to restore complete physical and cognitive function to individuals sustaining injuries of these regions. The two research groups discussed in this entry have independently devised and tested the use and efficacy of different materials in treating SCIs.
In their 2020 research article, "The effect of a nanofiber-hydrogel composite on neural tissue repair and regeneration in the contused spinal cord," Dr. Oudega et al. propose an injectable nanofiber-hydrogel composite (NHC) for the promotion of neural repair in the contused spinal cords of adult rats, tested against various other injectable hydrogels and an untreated control group. This research group sought to maximize both the mechanical strength and the porosity of the composite, in order to prevent the injured spinal cord from collapse and to encourage vascularization and axonal growth through the injured region. Their findings demonstrated that NHC better fulfilled these purposes than did simple hydrogels. In addition, the use of NHC was observed to give preference to pro-regenerative M2 macrophages in the injured region over the pro-inflammatory M1 phenotype.
Dr. Álvarez et al. report similarly successful results in their 2021 article, “Bioactive scaffolds with enhanced supramolecular motion promote recovery from spinal cord injury,” which details the use of injectable supramolecular polymers to which two bioactive signals are attached. One of these signals promotes neural stem cell differentiation and axonal growth, while the other promotes cellular proliferation. This research group tested the efficacy of several materials that varied in polymer composition and signals. It was observed that the most noticeable SCI recoveries occurred in mice treated with a coassembly of polymers which contained both signals and whose chemical structures minimized interactions between molecules and maximized mobility throughout the area. As a result, the regenerative signals associated with these molecules were allowed to interact with nearby cells and foster neurogenesis and angiogenesis in the contused region.
The results of both previously mentioned research groups have yet to be replicated in human subjects with SCIs similar to those of the rodent subjects, as well as being approved for common medical use. However, these findings demonstrate significant progress in the scientific community towards an effective and accessible treatment for SCIs. It would be valuable to determine whether the regenerative effects of the materials used in either experiment would be enhanced if a composite material were produced. Another question of note is whether a material, similar to those that mimicked the extracellular matrix of the spinal cord, could be produced which mimics the functions of glial cells lost to TBIs or neurodegenerative diseases.
References:
Álvarez, Z., Kolberg-Edelbrock, A. N., Sasselli, I. R., Ortega, J. A., Qiu, R., Syrgiannis, Z., Mirau, P. A., Chen, F., Chin, S. M., Weigand, S., Kiskinis, E., & Stupp, S. I. (2021). Bioactive scaffolds with enhanced supramolecular motion promote recovery from Spinal Cord Injury. American Association for the Advancement of Science, 374(6569), 848–856. https://doi.org/10.1126/science.abh3602
Li, X., Zhang, C., Haggerty, A. E., Yan, J., Lan, M., Seu, M., Yang, M., Marlow, M. M., Maldonado-Lasunción, I., Cho, B., Zhou, Z., Chen, L., Martin, R., Nitobe, Y., Yamane, K., You, H., Reddy, S., Quan, D.-P., Oudega, M., & Mao, H.-Q. (2020). The effect of a nanofiber-hydrogel composite on Neural Tissue Repair and regeneration in the contused spinal cord. Biomaterials, 245, 119978. https://doi.org/10.1016/j.biomaterials.2020.119978
Morris, Amanda. 'Dancing Molecules' Successfully Repair Severe Spinal Cord Injuries, news.northwestern.edu/stories/2021/11/dancing-molecules-successfully-repair-severe-spinal-cord-injuries/.
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