Current estimates suggest that approximately half of arteriovenous fistulas (AVF) fail to functionally mature and become regularly usable for hemodialysis by six months of surgical creation. The process of maturation (and its failure) is poorly understood, and no effective therapies to promote maturation are currently known. An NIDDK-sponsored "Hemodialysis Fistula Maturation (HFM)"(U01 DK-082189-01) cohort study is underway to examine whether a broad range of clinical, demographic, physiological and process-of-care variables in patients undergoing AVF placement influence maturation and usability of the AVF for dialysis. While the parent study will correlate pre-operative vascular function and venous histological features with post-operative ultrasound data, its largely global assessments will not furnish a detailed picture of the local and specific biological mechanisms that determine AVF maturation. Hence, the proposed ancillary clinical study examine the complex interplay between pre-existing endothelial and smooth muscle cell dysfunction, endothelial repair, and systemic inflammation. The specific objectives are (1) to delineate genome-wide expression patterns from endothelial and smooth muscle cells within the donor vein wall at the time of AVF creation, and to identify unique genomic patterns (i.e. "signatures") that are associated with AVF outward remodeling and changes in blood flow rate, (2) to determine the initial and ongoing balance between endothelial injury and repair following vein graft implantation, as defined by circulating endothelial cells (CECs) and endothelial progenitor cells (EPCs), and obtain novel genomic "signatures" of EPCs associated with a successful or unsuccessful AVF maturation, and, (3) to evaluate the role of systemic inflammation, as determined by genome-wide expression patterns of circulating monocytes, as they relate to AVF maturation and can be used to predict outcomes and identify novel pathways. We propose to enter 100 patients (50 patient test set, 50 patient validation set) at the University of Florida who will participate in the parent study. We propose to employ laser microdissection for endothelial and smooth muscle cell capture within the vein wall, as well as macro-scale and novel microfluidic capture technologies for blood EPCs and monocytes obtained preoperatively and on post-op day 14 for subsequent genome-wide expression analysis using a novel proprietary Affymetrix HH/2 exon array. Using these novel technologies, we will accomplish two major goals: (1) develop novel genomic signatures from vascular tissue cell populations and enriched blood leukocytes that can be used to predict a successful outcome, and (2) develop new insights into novel signaling pathways and potential mechanisms for therapeutic intervention. The proposed studies will effectively exploit the unique data collection effort in the parent HFM study and add both predictive genomic modeling of outcome, and significant mechanistic insight into the physiology and pathophysiology of AVF development.
Approximately half of all arteriovenous fistulas will fail to functionally mature and become usable for hemodialysis. This ancillary study to an NIDDK-sponsored Hemodialysis Fistula Maturation (HFM)(U01 DK-082189-01) cohort study will examine genome wide expression patterns in blood monocytes and endothelial precursor cells prior to and after graft creation, as well as from the vein graft itself. The overall goal is to generate prognostic indicators of graft success and develop new mechanistic insights into the causes of graft failure.