Endothelial progenitor cells in peripheral blood of cardiac catheterization personnel

ABSTRACT

The aim of the present study was to evaluate the rejuvenation capacity among cardiac catheterization technicians occupationally exposed to ionizing radiation. The individual annual collective dose information was measured by thermoluminscent personal dosimeters [TLD] for those technicians and found to be ranging between 2.16 and 8.44 mSv/y. Venous blood samples were obtained from 30 cardiac catheterization technicians exposed to X-ray during fluoroscopy procedures at the National Heart Institute in Embaba. The control group involved 25 persons not exposed to ionizing radiation and not working in hospitals in addition to 20 persons not exposed to ionizing radiation and working in hospitals. Blood samples were assayed for total and differential blood counts, micronucleus formation [FMN] plasma stromal derived growth factor-1alpha [SDF-1 alpha] and cell phenotype of circulating endothelial progenitor cells [EPCs], whose surface markers were identified as the CD34, CD133 and kinase domain receptors [KDR]. SDF-1alpha [2650 +/- 270 vs. 2170 +/- 430 pg/ml] and FMN [19.9 +/- 5.5 vs. 2.8 +/- 1.4/1000 cells] were significantly higher among cardiac catheterization staff compared to those of the controls respectively. Similarly, EPCs CD34 [53 +/- 3.9 vs. 48 +/- 8.5/10[5] mononuclear cells], CD133 [62.4 +/- 4.8 vs. 54.2 +/- 10.6 /10[5] mononuclear cells] KDR [52.7 +/- 10.6 vs.43.5 +/- 8.2 /10[5] mononuclear cells] were also significantly higher among cardiac catheterization staff compared to the values of controls respectively. Smoking seemed to have a positive effect on the FMN and SDF-1 but had a negative effect on EPCs. It was found that among cardiac catheterization staff, the numbers of circulating progenitor cells had increased and accordingly there was an increased capacity for tissue repair. In conclusion, the present work shows that occupational exposure to radiation, well within permissible levels, leaves a genetic mark on the somatic DNA of the cardiac catheterization technician. On the other hand, exposure of workers to ionizing radiation stimulates regenerative processes as indicated by the increase in EPCs numbers and SDF-1 levels. This regenerative process is decreased by smoking as evidenced by increased levels of SDF-1 and decreased numbers of EPCs. The technicians who work in cardiac catheterization laboratories should therefore carefully follow radiation protection procedures and should minimize radiation exposure to avoid possible genotoxic effects