Significance of circulating endothelial progenitor cells in patients with fracture healing process

Abstract

Fracture healing is a complex bone formation process, and neovascularization may contribute to new bone regeneration. The circulating endothelial progenitor cell (EPC) mobilization and homing could involve in neovascularization and vasculogenesis. In this study, we investigate the changes of circulating EPC during bone fracture healing, and the possible contribution of EPCs to increased neovascularization and fracture healing. The number of circulating EPCs was monitored in twenty-four patients with long bone traumatic fracture within the first 48 h and at 3, 5, 10, and 14 days post-fracture. The mononuclear cells which isolated from peripheral blood were analyzed by flow cytometry. Peripheral blood counts of leukocytes and platelets were measured by hematology analyzer. The amount of peripheral EPCs significantly increased in patients with fracture compared to age-matched healthy control subjects within the first 48 h after injury, and peaked at 3 days post-fracture. There was no significant difference in the change trend of early EPCs between male and female, but the number of early EPCs was significantly greater in younger patients compared to older patients. A comparison of the EPCs levels between patients with severe injury (ISS > 16) and patients with mild injury (ISS 16) revealed no statistically significant difference. The level of early EPCs was inverse correlation with the level of plate after fracture, but no correlation with the level of peripheral leucocytes. These findings suggest traumatic fracture may induce the mobilization of EPCs into the peripheral circulation. The increased EPCs may contribute to neovascularization and involve in fracture healing. ß

Mobilization of endogenous stem cell populations enhances fracture healing in a murine femoral fracture model

“…Eghbali-Fatourechi et al noted that circulating osteoprogenitor cell numbers increased at least 4-fold in a patient who had sustained a severe fracture 20 days earlier [60]. Another study by Ma et al demonstrated that peripheral EPC numbers significantly increased in patients within 48 hours after fracture and peaked around 3 days after injury [61]. In light of these and similar studies we had expected to see increased numbers of circulating cells in fractured mice and that this response would be enhanced in the presence of AMD3100 mobilization.…”

Pleiotropic effects of the dipeptidylpeptidase-4 inhibitors on the cardiovascular system

“…Repair of the injured endothelium is accomplished in large part by recruitment of circulating endothelial progenitor cells (EPCs). The role of endothelial repair is being increasingly recognized as a potential therapeutic target to improve endothelial dysfunction, myocardial ischemic injury, kidney injury, and bone marrow microangiopathy (10,44,112,119). The endothelium of individuals who are obese and diabetic is prone to endothelial injury that can lead to endothelial dysfunction and microvascular and macrovascular complications.…”

Cellular biology of fracture healing

“…Endothelial cells in forming callus vasculature can develop from a variety of sources, including, existing vessels of the periosteum and the intramedullary vasculature; circulating EPCs that are increased during fracture repair; or the bone marrow . Circulating EPCs are not only increased in rodent models, but are significantly increased in human patients at day three post‐fracture …”