Endothelial progenitor cells: a cardiovascular protective factor in Parkinson's disease?

Background: Parkinson’s disease (PD) patients have a favourable cardiovascular risk profile. Cardiovascular risk factors are inversely associated with circulating endothelial progenitor cells (EPCs). These cells are involved in the recovery of endothelial integrity, and their function and mobilization from the bone marrow are negatively affected by dopamine. Objective: To investigate EPC counts in PD and establish whether their count is affected by dopamine-replacement therapy. Patients and methods: We studied de novo (DPD; N = 27) and levodopa-treated (LTPD; N = 27) PD patients and control subjects (N = 54) free of comorbidities and matched (1:1:2) by age, gender and body mass index. Results: Both DPD and LTPD patients had higher EPC counts than controls (P < 0.001). No difference was detected between groups of PD patients. After adjusting for age, gender, total serum cholesterol and protein intake the difference between patients and controls remained significant (DPD, P = 0.020; LTPD, P = 0.045). High serum cholesterol and protein intake were also significant independent predictors of a reduced number of EPCs. In LTPD patients levodopa dosage (mg/kg/day) was directly associated with circulating EPC counts (P = 0.014). Conclusion.: PD patients have higher EPC counts than controls, independently of cardiovascular risk profile and dopamine-replacement therapy. A major contributing factor is likely the peripheral sympathetic denervation characterizing these patients. The determinants of circulating EPC counts in PD deserve further investigation. Future studies should address also the functional properties of EPCs in PD. Prospective studies controlling for relevant confounders are required to clarify the role of EPCs as a new marker of cardiovascular disease and risk in PD.