Current Assays for the Assessment of Endothelial Progenitor Cell Proliferation, Migration, and Paracrine Functions

Abstract

Endothelial progenitor cells (EPCs), a subset of bone-marrow derived pluripotent mononuclear cells, have been touted for their prognostic, diagnostic, and therapeutic value in the treatment of diseases of the vasculature. However, the results of the clinical trials of autologous EPC transplantation have been mixed, likely because the EPC function of patients who would benefit from autologous transplantation is compromised by genetic and environmental factors associated with pre-clinical and frank disease states. This finding, combined with an inability to assess the functional state of donor EPCs prior to transplantation, creates a significant barrier to their therapeutic application. Although there is currently substantial literature focusing on diseases that impact EPC function, there are no reviews that collate the obligate functions of EPCs for transplantation application. Across the literature, EPC functional assays assess six known abilities of these cells: pre-terminal differentiation, mobilization, proliferation, homing/migration, paracrine functions, and terminal differentiation. This review provides an overview of the current literature on the subset of functions that are crucial for therapeutic efficacy: proliferation, migration and paracrine functions. In this systematic review of over 400 publications, assays that assess these functions are described, organized and evaluated for application in pre-transplant assessment.