Warren J. Alilain, Ph.D. - US grants

? DESCRIPTION (provided by applicant): More than half of all spinal cord injuries (SCI) occur at the cervical level. At this level are the components of the central nervous system mediating respiratory motor activity, including the phrenic motor neurons which innervate the diaphragm and the bulbospinal tracts that provide the inspiratory drive to these cells. Therefore, injuries a this level can result in diaphragmatic paralysis and the inability to breathe. In order to survive, mechanical ventilation is needed for these patients, severely limiting their quality of life. In ths grant application we plan to utilize our newly developed cervical contusion injury model. This cervical contusion injury model is significantly improved compared to previous models of cervical injury in that accompanying it are severe respiratory motor deficits in a clinically relevnt setting. Additionally, with this model we can assay potential therapeutic interventions and their effect on repairing, strengthening, and/or promoting the plasticity of pathways damaged by SCI. Among these interventions is stem cell therapy. Previous work has demonstrated the effectiveness of multipotent adult progenitor cell (MAPC) therapy in restoring locomotor and bladder function in thoracic SCI models. We now propose to determine the effectiveness of MAPC treatment in rescuing the diaphragm from paralysis. If this cell therapy is indeed therapeutically beneficial, there would be a significant and positive impact for a major portion of the SCI population.

PROJECT SUMMARY/ABSTRACT More than 50% of all spinal cord injuries occur at the cervical level. At this level are the phrenic motor neurons which innervate the diaphragm. Therefore, injuries at this level can lead to the inability to breathe. The overall objective of this grant proposal is to examine the changes which take place chronically in the phrenic circuitry of the cord in response to cervical spinal cord injury and investigate and optimize potential therapies that can restore breathing long after injury. Through these studies, an effective intervention can be translated to a significant population of the spinal cord injured community. In this proposal we will utilize chronic cervical spinal cord-hemisected animals which have half of the diaphragm paralyzed. In our earlier studies we observed that enzymatic (chondroitinase ABC) removal of extracellular matrix molecules, called chondroitin sulfate proteoglycans, which block plasticity, regeneration, and sprouting, led to restoration of function of the once paralyzed hemidiaphragm when administered at or near the time of injury. Recovered diaphragmatic activity was rhythmic and synchronized. In stark contrast, when the spinal cord of chronically injured animals was stimulated with chondroitinase ABC and intermittent hypoxia training, chaotic and unstructured activity resulted, suggesting slowly developing and potentially maladaptive responses to injury. However, the use of chondroitinase alone at chronic stages can promote normal rhythm and dramatically enhance properly patterned functional recovery. This grant proposal seeks to: 1) understand the time course and carefully describe the maladaptive processes that take place; 2) understand the mechanisms underlying the production of this newly discovered atypical activity at chronic time points; and 3) learn how to overcome these negative responses to injury so that interventions and rehabilitative strategies can become more effective, thereby leading to improved functional outcomes. Overall, these studies will provide insight on the basic mechanisms that underlie maladaptive, as well as functionally beneficial plasticity that can lead to robust functional respiratory motor recovery at chronic stages of spinal cord injury.

PROJECT SUMMARY/ABSTRACT. Spinal cord injury (SCI) is a devastating lifelong affliction that impairs a number of functions including locomotion, breathing, autonomic regulation, and sensation/pain. Unfortunately, there is no current FDA approved therapy for SCI. Therefore, there is a critical need to translate basic science discoveries developed in the laboratory with promising effects after experimental SCI towards human application. SCI elicits an intraspinal inflammatory response comprised of resident glia and infiltrating blood leukocytes. Although subsets of resident and recruited immune cells have been implicated in CNS repair, more than 20 years of experimental data in different animal models of SCI indicate that acute monocyte depletion (MD) is consistently neuroprotective. Further, there are clinically viable drugs, such as clodronate, that can effectively deplete monocytes after SCI. However, a number of fundamental questions must be answered before successful translation including, understanding the extent to which injury level impacts therapeutic efficacy, as well as, understanding the long-term consequences of MD on functional recovery and monocyte repopulation and fate. Therefore, the goals of this proposal are to examine chronic and level-specific functional changes after acute MD using clinically relevant outcomes including pain, autonomic dysreflexia, respiration, and forelimb/hand function. We will study the effects of acute liposome encapsulated clodronate treatment for up to one year in rodent models of cervical and thoracic SCI. Specifically, this grant seeks to: Aim 1: evaluate the dose-response effects of acute MD on myelopoiesis, biodistribution, and toxicity; Aim 2: determine the efficacy of acute MD on recovery of locomotor, sensory, and autonomic function in chronic SCI rats. Aim 3: determine the effects of acute MD on recovery of respiratory motor and forelimb function after cervical SCI. The combined approach of examining the effects of MD after both cervical and thoracic SCI will provide unprecedented preclinical data regarding the effects of monocyte function on sensory, autonomic, pain, and respiratory outcomes. The feasibility of clodronate (aka disodium dichloromethylene diphosphonate) treatment in SCI individuals was reported almost 40 years ago therefore our proposal is significant as data from our studies could be adapted to treat human SCI and is expected to be of critical translational impact.