A proteomic investigation of protein adsorption to cerebral microdialysis membranes in surgically treated intracerebral hemorrhage patients

Abstract Background Cerebral microdialysis (CMD) is a minimally invasive technique for sampling the interstitial fluid in human brain tissue. CMD allows monitoring the metabolic state of tissue, as well as sampling macromolecules such as proteins and peptides. Recovery of proteins or peptides can be hampered by their adsorption to the CMD membrane as has been previously shown in-vitro, however, protein adsorption to CMD membranes has not been characterized following implantation in human brain tissue. Methods In this paper, we describe the pattern of proteins adsorbed to CMD membranes compared to that of the microdialysate and of cerebrospinal fluid (CSF). We retrieved CMD membranes from three surgically treated intracerebral hemorrhage (ICH) patients, and analyzed protein adsorption to the membranes using two-dimensional gel electrophoresis (2-DE) in combination with nano-liquid mass spectrometry. We compared the proteome profile of three compartments; the CMD membrane, the microdialysate and ventricular CSF collected at time of CMD removal. Results We found unique protein patterns for each of the three compartments, particularly in the molecular weight range of 10-35 kDa. Conclusion This study highlights the importance of analyzing the membranes in addition to the microdialysate when using CMD to sample proteins for biomarker investigation.