ESPE Abstracts

Background: Present knowledge on the effects of growth hormone (GH) on aging and lifespan are controversial. Clinical data indicate that normal or high levels of GH may accelerate aging and increase the risk of cardio-vascular diseases. Very small embryonic-like stem cells (VSELs) are a population of developmentally early stem cells residing in adult tissues, which could have the potential role in aging and organ rejuvenation.

Objective: The aim of the study was to analyze the effect of GH treatment on VSELs.

Methods: Twenty-five patients: GH-deficient (20), Turner Syndrome (3), Prader–Willi Syndrome (2), treated with GH, mean age 9.1±2.7 years were included in the study. The mean GH dose was 0.27 mg/kg/week. Fasting peripheral blood samples were taken before the administration of GH, then two-weeks, one-month, three-months and six-months after it. Subsequently, we evaluated by employing FACS changes in the number of small CD133⁺Lin^-CD45^-VSELs and CD34⁺Lin^-CD45^-VSELs – that are precursors of long term repopulating hematopoietic stem cells, mesenchymal stem cells (MSCs) and endothelial progenitor cells (EPCs). Statistical analysis was performed ANOVA.

Results: The administration of GH initially stimulated for a month an increase in number of VSELs, and subsequently the number of VSELs decreased. After six months of treatment the number of circulating in PB VSELs was lower as compared to baseline values (P=0.026). The increase in VSELs number paralleled with increase in number of circulating MSCs and EPCs, however two months shift has been observed in case of EPCs. Finally, the number of MSCs and EPCs become lower than before GH treatment.

Conclusions: The treatment with GH modulates the population of VSELs, MSCs and EPCs circulating in PB. Our data suggests that: 1/VSELs respond to GH treatment, and 2/since the therapy with GH modulates population of VSELs, therefore it could influence life span and organ rejuvenation.