Hydrogel-based local drug delivery strategies for spinal cord repair

Spinal cord injuries lead to loss of motor, sensory, and autonomic functions. Hydrogel-based drug delivery systems can deliver drugs locally to the injured spinal cord, achieving therapeutic concentrations while reducing side effects associated with systemic drug administration. These systems are made from biocompatible and biodegradable materials. Hydrogels can encapsulate drugs or drug-loaded carriers to provide sustained localized drug release. They can be implanted into parenchymal, intrathecal (subdural), or epidural spaces. Intrathecal implantation is often preferred as it bypasses barriers and doesn't cause additional tissue damage. Hydrogels can also be implanted directly into lesion cavities, functioning as both drug delivery systems and tissue engineering scaffolds to support tissue regeneration. Their high water content and mechanical similarities to native CNS tissue are advantageous.

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  Hydrogel pore size can be varied to control drug release, with larger pore sizes leading to faster drug release.
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  Drug release rate is also highly dependent on drug properties such as molecular weight, as larger molecules will be more sterically hindered from escaping the hydrogel network
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  Composite hydrogel systems combine temporal control over drug release with spatial control, increasing the percentage of drugs delivered to the injury site.