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 < .

Few investigators have evaluated the usefulness of the JAK2 V617F mutation for explaining the phenotypic variations and for predicting the risk of major clinical events in primary myelofibrosis (PMF). In a transversal survey we assayed by allelespecific polymerase chain reaction (PCR) the JAK2 V617F mutational status in 304 patients with PMF. Multiple DNA samples were collected prospectively from 64 patients, and a highly sensitive quantitative PCR was used as a confirmatory test. In a longitudinal prospective study we determined the progression rate to clinically relevant outcomes in 174 patients who had JAK2 mutation determined at diagnosis. JAK2 V617F was identified in 63.4% of patients. None of the V617F-negative patients who were sequentially genotyped progressed to become V617F positive, whereas progression rate from heterozygous to homozygous mutation was 10 per 100 patient-years. JAK2 V617F mutation contributed to hemoglobin, aquagenic pruritus, and platelet count variability, whereas homozygous mutation was independently associated with higher white blood cell count, larger spleen size, and greater need for cytoreductive therapies. Adjusting for conventional risk factors, V617F mutation independently predicted the evolution toward large splenomegaly, need of splenectomy, and leukemic transformation. We conclude that JAK2 V617F genotype should be considered in any future risk stratification of patients with PMF. (Blood. 2007;110: [4030][4031][4032][4033][4034][4035][4036]

Vitiligo is a common skin disease characterized by the presence of well circumscribed, depigmented, milky white macules devoid of identifiable melanocytes. Although the detection of circulating anti-melanocytic antibodies and of infiltrating lymphocytes at the margin of lesions supports the view that vitiligo is an autoimmune disorder, its etiology remains unknown. In particular, it is still a matter of debate whether the primary pathogenic role is exerted by humoral or cellular abnormal immune responses. In this study, the presence of specific cytotoxic T lymphocyte responses against the melanocyte differentiation antigens Melan-A/MART1, tyrosinase, and gp100 in vitiligo patients have been investigated by the use of major histocompatibility complex/peptide tetramers. High frequencies of circulating melanocyte-specific CD8+ T cells were found in all vitiligo patients analyzed. These cells exerted anti-melanocytic cytotoxic activity in vitro and expressed skin-homing capacity. In one patient melanocyte-specific cells were characterized by an exceptionally high avidity for their peptide/major histocompatibility complex ligand. These findings strongly suggest a role for cellular immunity in the pathogenesis of vitiligo and impact on the common mechanisms of self tolerance.

ECFCs are low at extremely low gestational ages and increase during gestation; extremely preterm infants who display lower numbers at birth have an increased risk of developing BPD. Our findings suggest that decreased ECFCs following extremely preterm birth may be associated with the risk for developing lung vascular immaturity characteristic of new BPD.

Clonal endothelial progenitor cells (EPCs) have been implicated in the aberrant vascular growth that features infantile hemangioma (IH), the most common benign vascular tumor in childhood that may cause ulceration, bleeding, and/or permanent disfigurement. Endothelial colony-forming cells (ECFCs), truly endothelial EPCs endowed with clonal ability and capable of forming patent vessels in vivo, remodel their Ca(2+) toolkit in tumor-derived patients to acquire an adaptive advantage. Particularly, they upregulate the proangiogenic store-operated Ca(2+) entry (SOCE) pathway due to the overexpression of its underlying components, that is, stromal interaction molecule 1 (Stim1), Orai1, and transient receptor potential canonical 1 (TRPC1). The present work was undertaken to assess whether and how the Ca(2+) signalosome is altered in IH-ECFCs by employing Ca(2+) and nitric oxide (NO) imaging, real-time polymerase chain reaction, western blotting, and functional assays. IH-ECFCs display a lower intracellular Ca(2+) release in response to either pharmacological (i.e., cyclopiazonic acid) or physiological (i.e., ATP and vascular endothelial growth factor) stimulation. Conversely, Stim1, Orai1, and TRPC1 transcripts and proteins are normally expressed in these cells and mediate a constitutive SOCE, which is sensitive to BTP-2, La(3+), and Pyr6 and recharges the intracellular Ca(2+) pool. The resting SOCE in IH-ECFCs is also associated to an increase in their proliferation rate and the basal production of NO compared to normal cells. Likewise, the pharmacological blockade of SOCE and NO synthesis block IH-ECFC growth. Collectively, these data indicate that the constitutive SOCE activation enhances IH-ECFC proliferation by augmenting basal NO production and sheds novel light on the molecular mechanisms of IH.

Increased microvessel density contributes to abnormal BM and spleen microenvironment in myelofibrosis (MF). Taking advantage of the JAK2V617F mutation as a marker of malignancy, in the present study, we investigated whether splenic endothelial cells (ECs) obtained from capillaries by laser microdissection or from fresh spleen tissue by cell culture or cell sorting harbored such mutation in patients bearing the mutation in their granulocytes and undergoing splenectomy for therapeutical reasons. To extend the analysis to the ECs of large vessels, endothelial tissue from the splenic vein was also studied. We found JAK2V617F+ ECs in 12 of 18 patients also bearing the mutation in their granulocytes. In 3 patients, the mutation was found in at least 2 different EC samples obtained by laser microdissection, cell culture, or cell sorting. The mutation was detected in the splenic vein ECs of 1 of 6 patients investigated. In conclusion, we provide evidence that some ECs from the spleen and splenic veins of patients with MF bear the JAK2V617F mutation. We suggest that splenic ECs are involved in the process of malignant transformation in MF.

PurposeIn the WHO diagnostic classification, prefibrotic myelofibrosis (pre-MF) is included in the category of primary myelofibrosis (PMF). However, strong evidence for this position is lacking.Patients and MethodsWe investigated whether pre-MF may be aligned along a clinical and biological continuum in 683 consecutive patients who received a WHO diagnosis of PMF.ResultsAs compared with PMF-fibrotic type, pre-MF (132 cases) showed female dominance, younger age, higher hemoglobin, higher platelet count, lower white blood cell count, smaller spleen index and higher incidence of splanchnic vein thrombosis. Female to male ratio and hemoglobin steadily decreased, while age increased from pre-MF to PMF- fibrotic type with early and to advanced bone marrow (BM) fibrosis. Likely, circulating CD34+ cells, LDH levels, and frequency of chromosomal abnormalities increased, while CXCR4 expression on CD34+ cells and serum cholesterol decreased along the continuum of BM fibrosis. Median survival of the entire cohort of PMF cases was 21 years. Ninety-eight, eighty-one and fifty-six percent of patients with pre-MF, PMF-fibrotic type with early and with advanced BM fibrosis, respectively, were alive at 10 years from diagnosis.ConclusionPre-MF is a presentation mode of PMF with a very indolent phenotype. The major consequences of this contention is a new clinical vision of PMF, and the need to improve prognosis prediction of the disease.

No abstract