Diminished radiolabeling efficiency of progenitor cells using indium-111 oxine

Abstract Background: Progenitor cells have enormous potential for forming new blood vessels and myocytes and thereby limiting infarct size and restoring cardiac function after ischemic injury. Nearly all studies following progenitor cell transplantation use post-mortem histochemical analysis to determine the fate of administered cells. The development of a non-invasive imaging approach for in-vivo monitoring would be highly desirable. The purpose of this study was to evaluate the labeling efficacy of indium-111 (In-111) oxine for progenitor cells. Methods: Mature human peripheral leukocytes (WBCs) as well as cytokine mobilized unfractionated and CD34+ selected progenitor cells were labeled with In-111 oxine following preliminary studies to determine optimal labeling conditions. After washes with physiological saline, cells were incubated with In-111 oxine for 20 min. Then, to remove unbound activity, cells were washed with autologous plasma. Results: Radiolabeling efficiency (% of administered activity incorporated into cells) was higher for WBCs than for unfractionated or CD34+ selected cells (Figure). Viability as determined by trypan-blue dye exclusion was > 98% for all cell types. Conclusions: Compared to peripheral WBCs, progenitor cells demonstrate a lower labeling efficiency using In-111 oxine. Nonetheless, CD34+ cells can be labeled with sufficient efficiency to permit non-invasive imaging. Download : Download full-size image