Vascular progenitor recruitment in critically ill patients with acute kidney injury.

Purpose: Endothelial-like vascular progenitor cells (VPCs) are blood-derived angiogenic precursors that can facilitate vascular repair. The mobilization of peripheral blood VPCs and their role in recovery were investigated in patients with acute kidney injury (AKI) in the intensive care unit (ICU) setting.

Methods: Blood samples were drawn on days 0, 3, 7 and 14 in 38 patients admitted to ICU: 30 with AKI and in eight controls with normal renal function. Circulating VPC levels were quantified by the early outgrowth cell cluster-forming assay and/or by flow cytometry.

Results: AKI patients (16 males, mean age 62.4) were classified as Risk (R, n=5), Injury (I, n=11) and Failure (F, n=14) according to the RIFLE criteria. VPC clusters increased over time following the diagnosis of AKI (p < 0.01 for day 0 vs. day 14) while VPC clusters were higher at enrollment in control patients and decreased over time (p=0.02). Greater mobilization of VPCs occurred in patients with more severe AKI at enrollment (I and F categories compared with R, p=0.05). A trend towards greater mobilization of VPC clusters was observed in patients with improved renal function (p=0.07).

Conclusion: Time-dependent increases in circulating VPCs occur in critically ill patients with established AKI. Greater mobilization of VPCs may be associated with recovery of renal function, suggesting a potential role for VPCs in repair after kidney injury.