A rationally designed self-immolative linker enhances the synergism between a polymer-rock inhibitor conjugate and neural progenitor cells in the treatment of spinal cord injury.
Biomaterials 2021;
276:121052. [PMID:
34388362 DOI:
10.1016/j.biomaterials.2021.121052]
[Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 07/04/2021] [Accepted: 07/24/2021] [Indexed: 10/24/2022]
Abstract
Rho/ROCK signaling induced after spinal cord injury (SCI) contributes to secondary damage by promoting apoptosis, inflammation, and axon growth inhibition. The specific Rho-kinase inhibitor fasudil can contribute to functional regeneration after SCI, although inherent low stability has hampered its use. To improve the therapeutic potential of fasudil, we now describe a family of rationally-designed bioresponsive polymer-fasudil conjugates based on an understanding of the conditions after SCI, such as low pH, enhanced expression of specific proteases, and a reductive environment. Fasudil conjugated to poly-l-glutamate via a self-immolative redox-sensitive linker (PGA-SS-F) displays optimal release kinetics and, consequently, treatment with PGA-SS-F significantly induces neurite elongation and axon growth in dorsal root ganglia explants, spinal cord organotypic cultures, and neural precursor cells (NPCs). The intrathecal administration of PGA-SS-F after SCI in a rat model prevents early apoptosis and induces the expression of axonal growth- and neuroplasticity-associated markers to a higher extent than the free form of fasudil. Moreover, a combination treatment comprising the acute transplantation of NPCs pre-treated with PGA-SS-F leads to enhanced cell engraftment and reduced cyst formation after SCI. In chronic SCI, combinatory treatment increases the preservation of neuronal fibers. Overall, this synergistic combinatorial strategy may represent a potentially efficient clinical approach to SCI treatment.
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