Recently, several distinct populations of cells that appear to correlate with or influence postnatal cardiovascular health have been identified. Many of these may be referred to as “angiogenic cells”, i.e. cells that support or augment angiogenesis, without actually differentiating into the cells that form part of the vascular network.
A cell culture assay was developed by Hill et al. to assess the correlation between the frequency of a specific population of circulating cells, clinical factors, and vascular function. In this widely used assay, peripheral blood mononuclear cells are plated on fibronectin-coated dishes. After 2 days, the non-adherent cells (which contain the cells of interest) are harvested and replated on fibronectin-coated dishes. Colonies, defined as a central core of “round” cells, with more elongated “sprouting” cells at the periphery, are evaluated and quantified 3 days later. In healthy individuals, the number of colonies negatively correlated with the Framingham cardiovascular risk score and positively correlated with vascular function, as measured by flow-mediated brachial artery reactivity. STEMCELL Technologies has standardized this 5-day assay and refers to it as the 5-Day CFU-Hill Colony Assay.