Stimulation of Human Hematopoiesis: The Androstene Link.

5-Androstene-3β, 17β-diol (AED) is a naturally occurring member of the androstene series of steroids. In models of chemotherapy and radiation-induced mylosuppression, AED expanded hematopoietic stem and progenitor cells (HSPC), decreased need for clinical support and increased survival. We studied hematopoietic activity of AED vs. Placebo in healthy adult (20–64 years, n=9) and elderly (65–72 years, n=9) subjects. AED was safe and well tolerated. Complete blood counts were serially obtained between study days 1–56. Bone marrow (BM) samples were obtained on days -1 and 7. AED produced significant increases in average neutrophil counts (NT) and platelet counts (PLT) as compared to placebo. Adult NT significantly increased between days 2–7 (40–73%, p=0.05) and persisted through day 28 (41.5%); adult PLT increased (19.9%) by day 14, and achieved significance by day 21 (15.6%, p=0.01) and increases persisted through day 28 (19.4%, p=0.02). In elderly subjects, NT significantly increased by 56–96% (days 4–6, p=0.05) which persisted through day 28 (30.7%). Fewer elderly subjects demonstrated robust PLT responses; maximum increase in PLT was seen on day 14 (31.5%) and persisted through day 28. BM samples at day 7 showed increased cellularity in AED but not placebo-treated subjects which was consequently reflected as an increase in peripheral blood NT and PT in AE-treated subjects. BM phenotype changes and maturation potential were estimated from immunophenotyping and CFU assay in vitro. BM precursor populations were elevated in most treated subjects on day 7; this reflected an activity of AED on precursor cells that resulted in a decrease in the CD34+CD38− and CFU-F populations and an increase in erythrocyte (BFU-E, CFU-E), and granulocyte (CFU-GM) precursors and megakaryocytes. Elderly patients (but not adults) had increased levels of two angiogenic factors; vascular endothelial growth factor and plasminogen activator inhibitor-1 in plasma (day 5) and in BM (day 7). These findings suggest that AED has a regenerative role in elderly BM and that the stimulation of angiogenic factors precedes an increase in BM cellularity which in turn leads to an increase in circulating terminally differentiated blood elements.