ECE2014 Poster Presentations Developmental Endocrinology (6 abstracts)
Objectives: GH plays a crucial role in the regulation of metabolism of human cells. Nevertheless, a direct influence of this hormone on the proliferation, maturation and differentiation of human early hematopoietic stem/progenitor cells (HSPCs) has not been investigated thoroughly. Moreover, certain deviations of hematological parameters, such as anemia or leucopenia, are commonly observed in patients with growth hormone deficiency (GHD) syndrome, which might be substantially compensated during the therapeutic GH supplementation. However, the mechanisms of GH cellular action and interactions with HSPCs from these patients are not well known. We explored whether the possible impairment of GH-mediated regulatory mechanisms in human hematopoiesis has any direct influence on proliferation/differentiation of HSPCs collected from patients with GHD, who underwent the exogenous GH supplementation therapy.
Materials and methods: Blood-derived CD34+-enriched HSPCs were isolated from GHD patients at the time of diagnosis, and subsequently in the 3rd and 6th month of the scheduled regular GH therapy. Healthy volunteers served as controls. The expression of the growth hormone receptor (GHR) on HSPCs was examined by flow cytometry and immunocytofluorescence. Next, the growth of granulocytemacrophage colony-forming units (CFU-GM), erythrocyte burst-forming units (BFU-E) and lymphocyte colony-forming units (CFU-L) was determined in clonogeneic in vitro assays. Additionally, the gene expression of the cell-cycle regulatory molecule, such as proliferating cell nuclear antigen (PCNA) was examined by qRT-PCR.
Results: GHR expression was detected at the protein level in the population of human early HSPCs. GHD patients displayed decreased clonogeneic potential of BFU-E, GM-CFU and CFU-L, which was significantly increased after prolonged GH therapeutic supplementation. Similarly, GH supplementation activated the molecular response of HSPCs through an increase in PCNA gene expression in the analyzed cells.
Conclusions: We have shown that GH may directly play a significant role in the regulation of growth and differentiation of human early hematopoietic stem/progenitor cells.