Circulating CD34+, CD133+, and vascular endothelial growth factor receptor 2-positive endothelial progenitor cells in myelofibrosis with myeloid metaplasia.

PURPOSE: Endothelial progenitor cells (EPCs) are present in circulation and contribute to vasculogenesis in adults. We measured the number of circulating EPCs in patients with myelofibrosis with myeloid metaplasia (MMM), and we examined the relationship between the number of EPCs and severity of the MMM disease process. PATIENTS AND METHODS: The number of EPCs was measured by assaying the CD34+CD133+ vascular endothelial growth factor receptor 2 (VEGFR2) -positive cell phenotype in 110 MMM patients, 16 patients with other Philadelphia-negative chronic myeloproliferative disorders (Ph-negative CMPDs), and 14 healthy participants. In four MMM patients, the capacity of selected CD34+ cells to form endothelial colonies (CFU-End) in vitro was tested. RESULTS: CD34+, CD133+, and VEGFR2-positive EPCs were detectable in unselected peripheral-blood cells of 50.9% MMM patients, 37.5% control patients, and 21% healthy participants. Patients with MMM had a median of 0.26% EPCs, significantly higher than that in healthy controls (median, 0%) and in patients with other Ph-negative CMPDs (median, 0.1%). In 14.5% of MMM patients, the numbers of EPCs were greater than the highest value found in patients with other Ph-negative CMPDs. CD34+ selected cells produced colony-forming unit-endothelial (CFU-End), which were vascular endothelial (VE) -cadherin positive, CD31+, von Willebrand factor positive, and CD45-. In MMM patients, the larger the number of EPCs, the smaller the number of circulating immature myeloid cells and circulating CD45+CD34+ hematopoietic progenitor cells. Increased numbers of EPCs were associated with younger age and a diagnosis of prefibrotic MMM. CONCLUSION: Circulating EPCs are elevated in MMM patients in the early stage of the disease. Heightened mobilization of EPCs may represent an important mechanism for development of neoangiogenesis in MMM.

Thalidomide treatment reduces apoptosis levels in bone marrow cells from patients with myelodysplastic syndromes.

We treated with thalidomide seven patients with primary MDS and observed reduction of the transfusion requirement in three cases and reduction of bone marrow blasts in one case. The apoptotic rate of bone marrow cells diminished significantly from a mean of 43.8% to a mean of 17.5%, whereas the proliferative activity did not change. Plasma TNF-alpha, bFGF, IL-1beta levels decreased variably, whereas VEGF levels tended to increase. Matrix metalloproteinases 2 and 9 expression decreased in bone marrow cells of responders. A reduction of CD4 cells and an increase of NK cells was observed in the peripheral blood. Thus, thalidomide may produce a fairly good hematological improvement in erythroid series in MDS, with complex biological mechanisms.

Increased circulating hematopoietic and endothelial progenitor cells in the early phase of acute myocardial infarction.

Endothelial progenitor cell (EPC) mobilization has been reported following tissue damage, whereas no data are available regarding the mobilization of hematopoietic progenitor cells (HPCs). We performed the phenotypic and functional analysis of circulating CD34+ progenitor cells in patients with acute myocardial infarction (AMI), assessed from admission up to 60 days, in patients with stable angina pectoris (SA), and in healthy controls (CTRLs). In patients with AMI at admission (T0), the number of circulating CD34+ cells was higher (P < .001) than in CTRLs and became comparable with CTRLs within 60 days. Both the number of CD34+ cells coexpressing CD33, CD38, or CD117 and the number of HPCs was higher (P < .02 for all) in patients with AMI at T0 than in CTRLs, as was the number of hematopoietic colonies (P < .03). Patients with AMI (T0) had a significantly increased number of CD34+ vascular endothelial growth factor receptor 2-positive (VEGFR-2+) cells (P < .002) with respect to CTRLs, including CD34(+) CD133(+)VEGFR-2+ and CD34+ CD117(+)VEGFR-2+ EPCs. The number of endothelial colonies was higher in patients with AMI (T0) than in CTRLs (P < .05). No significant difference was documented between patients with SA and CTRLs. Spontaneous mobilization of both HPCs and EPCs occurs within a few hours from the onset of AMI and is detectable until 2 months.

Clinical and biological effects of treatment with amifostine in myelodysplastic syndromes.

We treated six patients with primary myelodysplastic syndrome (MDS) with amifostine (200 mg/m(2) i.v./three times a week for three consecutive weeks). Neutrophil counts were more frequently increased than platelet and reticulocyte counts, but no reduction of the transfusion requirement was observed. Significant reduction of the marrow blasts was observed in one case of refractory anaemia with excess of blasts. In vitro stimulation of haematopoiesis was observed in five cases. The apoptotic rate of marrow cells was significantly diminished even after the first course. Our findings show fairly good clinical and biological response to amifostine in MDS.