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Spinal cord injury (SCI) causes immediate damage to the nervous tissue accompanied by loss of motor and sensory function. The limited self-repair competence of injured nervous tissue underscores the need for reparative interventions to recover function after SCI. The vasculature of the spinal cord plays a crucial role in SCI and repair. Ruptured and sheared blood vessels in the injury epicenter and blood vessels with a breached blood-spinal cord barrier (BSCB) in the surrounding tissue cause bleeding and inflammation, which contribute to the overall tissue damage. The insufficient formation of new functional vasculature in and near the injury impedes endogenous tissue repair and limits the prospect of repair approaches. Limiting the loss of blood vessels, stabilizing the BSCB, and promoting the formation of new blood vessels are therapeutic targets for spinal cord repair. Inflammation is an integral part of injury-mediated vascular damage, which has deleterious and reparative consequences. Inflammation and the formation of new blood vessels are intricately interwoven. Biomaterials can be effectively used for promoting and guiding blood vessel formation or modulating the inflammatory response after SCI, thereby governing the extent of damage and the success of reparative interventions. This review deals with the vasculature after SCI, the reciprocal interactions between inflammation and blood vessel formation, and the potential of biomaterials to support revascularization and immunomodulation in damaged spinal cord nervous tissue.

Spinal cord injury (SCi) results in permanent loss of function leading to often devastating personal, economic and social problems. A contributing factor to the permanence of SCi is that damaged axons do not regenerate, which prevents the re-establishment of axonal circuits involved in function. Many groups are working to develop treatments that address the lack of axon regeneration after SCi. The emergence of biomaterials for regeneration and increased collaboration between engineers, basic and translational scientists, and clinicians hold promise for the development of effective therapies for SCi. A plethora of biomaterials is available and has been tested in various models of SCi. Considering the clinical relevance of contusion injuries, we primarily focus on polymers that meet the specific criteria for addressing this type of injury. Biomaterials may provide structural support and/or serve as a delivery vehicle for factors to arrest growth inhibition and promote axonal growth. Designing materials to address the specific needs of the damaged central nervous system is crucial and possible with current technology. Here, we review the most prominent materials, their optimal characteristics, and their potential roles in repairing and regenerating damaged axons following SCi.Keywords: spinal cord injury; axon regeneration; biodegradable materials; extracellular matrix proteins; functional recovery; growth factor; guidance; injury and repair; spinal motor neuron IntroductionSpinal cord injury (SCi) causes loss of neurons and axons resulting in motor and sensory function impairments. There are thousands of new cases of SCi in the world annually [1,2] occurring often in young adults. The lack of endogenous repair and the significant costs to the individual, family and society [1] are important motivations behind the continuing efforts to develop effective therapies. Promoting axonal regeneration is considered a potential repair strategy because it could lead to recovery of axonal circuits involved in motor and/or sensory function [3] .The central nervous system (CNS) neurons are intrinsically capable of some regeneration of damaged axons [4] but their attempts after SCi are frustrated by structural and chemical obstructions in the damaged nervous tissue [5] . Spinal cord repair approaches typically lead to small functional gains. one feature that most of these approaches have in common is a poor axonal regeneration response, suggesting that promoting axonal regeneration, including synapse formation, is essential to achieve substantial functional repair after SCi. if so, it is rational to anticipate that effective spinal cord therapies will need to include interventions addressing the axon growth-inhibition that leads to the poor axonal growth responses. As introduced above, axonal regeneration is considered an important repair mechanism for the injured spinal cord. Therefore, this review focuses on materials that have shown most promise to elicit an axonal regeneration response to foster functional restoration after ...

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