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Recent findings have indicated the association between APC-resistance and cerebrovascular disease. These reports prompted us to investigate whether resistance to APC could be found in patients suffering from stroke.Therefore, we studied APC-resistance in 50 young adults (or =45 yrs) with a history of ischemic stroke. Eleven out of fifty cerebrovascular subjects showed APC-resistance, while 2 had PC deficiency and 3 PS deficiency. No deficiencies in the anticoagulant protein AT III and in fibrinolytic proteins were found. The family history demonstrated a distribution of APC-resistance compatible with dominant autosomal inheritance. The plasma concentration of prothrombin fragment 1+2 (F1+2), which is a marker of hypercoagulable states, was also measured in patients and family members of resistant subjects (n = 38).DNA analysis showed factor V R506Q mutation (Leiden mutation) in 11 patients and their relatives with poor response to activated protein C detected by APTT tests. Of 11 investigated subjects with APC-resistance, 9 were heterozygotes and 2, with the lowest APC-ratio values, were homozygotes for factor V mutation. Among 38 relatives, 22 showed a poor response to APC and according to the APC-ratio values, 18 were heterozygotes and 4 homozygotes for FV Leiden mutation. The mutation, in heterozygous form, was also found in 2% of our normal population (n = 100). The plasma concentration of F1+2 was significantly higher both in 11 individuals carrying the FV:Q506 mutation and in 39 patients without APC-resistance compared to that found in the control group. However, the patients with FV:Q506 mutation showed the highest values in F1+2. In the studied family members F1+2 plasma levels were within normal values.Our findings indicate a possible involvement of APC-resistance in the pathogenesis of cerebral thrombosis in young adults and agree with the hypothesis that individuals with APC-resistance have an imbalance between pro-and anti-coagulant forces leading to increased thrombin generation and a hypercoagulable state.

Endothelial progenitor cells (EPCs) play a role in endogenous neovascularization of ischaemic tissues. Isolation and characterization of EPCs from circulating mononuclear cells are important for developing targeted cellular therapies and reproducibility of data are the major scientific goals. Here we compared two currently employed isolation methods, i.e. from total peripheral blood mononuclear cells (PBMCs) and from enriched CD133+ cells, by defining the cell morphology and functional activities. We show that EPCs from cultured PBMCs resulted in an adherent population of 23% ± 4% merged cells positive for Dil-Ac-LDL and lectin, whereas the percentage of double positive cells in cultured CD133+ enriched cells was 50% ± 7% (P < 0.01). These data were obtained through a novel and a more complete method of analysis of cell calculations (specifically by dividing each microscope field into 120 subfields). When stimulated with tumour necrosis factor α (TNF)-α and glucose, cell number was reduced in EPCs from total PBMCs and, more consistently, in CD133+ enriched cells. However, both cultured total PBMCs and CD133+ enriched cells respond similarly to TNF-α or glucose-induced p38-phosphorylation.EPCs from both procedures show similar results in terms of phenotype and response to modulators of their functional activities. However, when the cell phenotype of CD133 + enrichment-derived cells was compared with that of cells from the total PBMC, a significant increase in CD133+ expression was observed (P < 0.01) This may have relevance during intervention studies using cultured EPCs. © 2007 The Japanese Biochemical Society.