Abstract
Calcium-dependent cysteine proteases, known as calpains, emerge as important regulators of spinal cord physiology, plasticity, and pathology. First characterized in the brain, they influence a wide range of processes in the spinal cord, maintaining neuronal homeostasis, shaping both synaptic and intrinsic plasticity, and modulating glial responses. When dysregulated, calpains contribute to the pathophysiology of traumatic and neurodegenerative spinal cord disorders, as well as to their associated motor and sensory complications, including spasticity and neuropathic pain. A recurring feature of these conditions is calpain-mediated proteolysis of ion channels, transporters, and cytoskeletal proteins, which promotes disinhibition and neuronal hyperexcitability. The resultant protein fragments are examined as prospective biomarkers for damage and disease progression. Meanwhile, promising strategies for neuroprotection and functional recovery in the clinic emerge as a result of innovative pharmacological and genetic approaches to modulate calpain activity. In this review, we present the current state of knowledge regarding the functions and regulation of calpains in the spinal cord and assess their translational potential as both therapeutic targets and effectors in spinal cord disorders.