Editorial [Hot Topic: Spinal Cord Injury and Repair - Part II (Executive Editor: Weihong Pan)]

The first half of the Special Issue has discussed many strategies for spinal cord repair. In this latter half, more emphasis is placed on pathophysiological changes and functional modalities after SCI. The blood-spinal cord barrier (BSCB, a component of the BBB) is a dynamic regulatory interface and participates in the exchange of information between the injured spinal cord and the periphery. Sharma provides a superb review of BSCB changes, addressing different animal models of SCI, spinal cord edema, ischemia, cellular and molecular alterations, ultrastructural changes, and spinal cord evoked potentials. Sharma has been a leader in SCI studies of tumor necrosis factor α (TNFα), serotonin, prostaglandin, bradykinin, opioid peptides, naloxone, as well as excitatory and oxidative stress [7]. His paper is followed by a review of the pioneering studies of Hermann, Holmes, and Rogers [8]. Hermann et al. have focused on α unique and extremely important field of spinal cord modulation concerned with the question of how TNFα mediates mind-body interactions by its interface with the vago-vagal neurocircuitry in the brainstem. Despite its name “cachexin”, it is less well known that TNFα causes "visceral malaise" by reducing gastric motility. Discussed in the review are potentiation of vagovagal responsiveness by TNFα and its mechanisms of action on the dorsal vagal complex and neurons of the solitary tract and area postrema. The studies have provided insight into the role of TNFα in neuronal excitability and chronic pain after SCI. Central neuropathic pain (CNP) is extremely devastating in survivors of chronic SCI. An expert in this field, Claire Hulsebosch, presents a thorough review of the pain phenomena (and terminology), animal models of pain, the pathophysiological mechanisms that provide the substrates for CNP, current treatment, and future strategies [9]. This major review bridges basic research and clinical studies. In the direction of patient care, Giorgio Brunelli discusses the pioneering clinical studies of peripheral nerve grafts to re-establish CNS-PNS connections [10]. The detailed procedures and functional assessment are well illustrated by figures accompanied by concise text. Next, in their excellent review, Kern, McKay, Dimitrijevic and Dimitrijevic discuss motor control after complete and incomplete human SCI, examine the neural circuitry involved in cutaneous and muscle stretch responses as elicited by single and regular repeating stimuli, and provide insight into future neurobiological interventions [11]. The electrophysiological assessment of neurorehabilitation leads to further questions about neuroplasticity. In the last paper, Ding, Kastin and Pan summarize the different levels of neural plasticity and discuss their potential functional implications [12]. A review of the exciting new developments in the field of SCI must be inspiring for young researchers like Ding who is starting on an enlightened path filled with enthusiastic investigators continuing to provide rich new information for such a worthwhile goal. We are extremely happy that each author of this Special Issue of “Spinal cord injury and repair” has made such an outstanding contribution. Unavoidably, we were unable to invite many other experts in the field to join the discussion and thereby may have missed some important aspects. Regardless, we hope that this Special Issue will provoke more discussion and facilitate more studies in areas such as the blood-spinal cord barrier, cytokine transport, central neuropathic pain, and autonomic nervous system regulation after SCI.