Cerebral spinal fluid serotonin and adenosine levels detect secondary injuries in traumatic spinal cord injury patients

Project Summary and Abstract. Candidate: My primary career objective is to lead a research program focused on preventing secondary insults in spinal

cord injury (SCI) patients. This proposal is an extension of established skills in small molecule detection with focused time

to learn new skills; 1) defining associations between early interventions and rehabilitation trajectories, and 2) clinical trial methodology. Environment: This proposal will be pursued under the mentorship of Drs. Shutter and Sowa, both

neurotrauma experts actively leading translational clinical trials with a record of training independent trialists. The U. of Pittsburgh is a premier program with established infrastructure that includes institutionally approved protocols incorporating the proposed research, a biobank of over 100 stored patient samples, and all necessary equipment and

supplies. Research: Traumatic SCIs result in devastating disability. Following the initial traumatic insult (i.e. primary injury) local tissue injury initiates a cascade of mechanisms that lead to prolonged ischemic and cytotoxic cell damage (i.e.

secondary injury). We lack strategies to limit pervasive secondary cell damage known to amplify disability and undermine recovery potential. The central hypothesis guiding this proposal is that cerebral spinal fluid (CSF) serotonin and

adenosine represent sensitive biomarkers detecting secondary injuries. This study represents the first step in developing effective treatment strategies to ameliorate secondary injuries and limit SCI disability. This proposal includes two

independent phases, a retrospective analysis of hypoxic cell damage (K99), and a prospective evaluation of cytotoxic cell damage (R00), both utilizing high pressure liquid chromatography (HPLC) analysis of CSF samples. All spinal serotonin

originates from brainstem raphe nuclei with descending projections to facilitate synthesis, delivery, and local intracellular storage at terminals near sensory and motor synapses. Rodent SCI models demonstrate transient spikes in extracellular

serotonin with amplitudes correlating to degree of motor deficit; suggesting serotonin is a biomarker for cellular damage. Using stored CSF samples from human subjects with traumatic SCIs, I demonstrate analogous serotonin spikes following

ischemic cell damage (i.e. secondary injury). The objective of aim 1 is to test the hypothesis that [secondary] ischemic

cord injuries increase CSF serotonin levels in human SCI subjects. Human neurons exhibit a limited capacity for structural

recovery, and serotonin release is theorized to be an indication of irreversible cell damage. It therefore benefits us to

identify biomarkers for “at risk” tissue, prior to irreversible damage. Extracellular (i.e. CSF) adenosine levels correlate to

degree of hypoxic stress with levels increasing during progressively severe and prolonged hypoxia. In aim 2 I will test the hypothesis that CSF adenosine levels increase with degree of cord hypoxia, prior to ischemic injury. Spinal hematomas and cord inflammation lead to non-ischemic cytotoxic cell damage as blood products and pro-apoptotic cytokines promote

cell damage/death. In aim 3 I will test the hypothesis that CSF serotonin is a sensitive biomarker for cytotoxic cell damage. Future studies will compare the capacity for molecular, imaging and physiological biomarkers to direct acute interventions that may limit SCI disability.