Reduced numbers of circulating endothelial progenitor cells in patients with coronary artery disease associated with long-term statin treatment

Elevated circulating endothelial progenitor marker CD133 messenger RNA levels predict colon cancer recurrence

BACKGROUND

CD133 is a specific surface marker for bone marrow-derived circulating endothelial progenitors, which are vital in postnatal physiologic and pathologic (eg, tumor) angiogenesis. In this study, the authors examined whether increased levels of expression of CD133 messenger RNA (mRNA) in peripheral blood predicted disease recurrence in patients with colon cancer.

METHODS

Semiquantitative real-time reverse transcriptase-polymerase chain reaction analysis was used to quantify CD133 mRNA levels in peripheral blood mononuclear cells from patients with colon cancer. The assay was developed first and tested at laboratory A (n = 34) and then was validated independently at laboratory B (n = 66). All patients were enrolled between February 2002 and December 2003. A central statistician performed the analysis.

RESULTS

At laboratory A, the median CD133 mRNA level was elevated in patients with recurrent disease (4.2; range, 0.017-106.9) compared with patients without recurrence (0.0017; range, 0.0-9.51; P < .001), leading to a 14.6 odds ratio of recurrence (95% confidence interval [95% CI], 1.7-126; P = .004). At laboratory B, it was confirmed that elevated CD133 mRNA levels at a cutoff point >or=4.79 versus <4.79 were associated with an odds ratio of 22.6 for recurrence (95% CI, 1.7-291.2; P = .02). By comparison, the odds ratio for recurrence was 17.2 (95% CI, 1.8-164; P = .01) for patients with stage III-IV disease versus stage I-II disease according to the Tumor, Lymph Node, Metastasis (TNM) classification. An association also was observed between elevated carcinoma embryonic antigen levels (P = .03; 1-sided) and decreased survival (P = .035; 1-sided) with a CD133 mRNA cutoff level of >or=4.79.

CONCLUSIONS

Elevated CD133 mRNA levels at >or=4.79 predicted colon cancer recurrence independent of TNM stage IV disease. Larger prospective studies comparing the current assay with standardized methodology are warranted.

Simvastatin enhances endothelial differentiation of peripheral blood mononuclear cells in hypercholesterolemic patients and induces pro-angiogenic cytokine IL-8 secretion from monocytes

BACKGROUND

Statins are known to have pleiotropic effects. We examined the effect and mechanism of simvastatin therapy on EPC differentiation and pro-angiogenic cytokines in patients with hypercholesterolemia.

METHODS

Twenty-two hypercholesterolemia patients without any other modifiable cardiovascular risk factors or history of previous lipid-lowering therapy were given simvastatin 20 mg/day for 4 weeks. Blood were drawn pre- and post-therapy. The in vitro effects of simvastatin were studied in a separate set of experiments.

RESULTS

Simvastatin treatment significantly increased the number of DiI-acLDL, UEA-1 lectin double-positive EPCs and facilitated its appearance. By FACS analysis of freshly isolated PBMNCs, KDR (+) cells increased after simvastatin treatment while there were no differences in CD34, AC133, and VE-cadherin. Also, serum concentration of IL-8 was markedly increased, while VEGF was only slightly increased. In vitro, PBMNCs co-cultured with simvastatin showed increased cluster formation at day 7, and simvastatin facilitated the appearance and networking of EPCs compared with vehicle. Simvastatin-co-cultured PBMNCs showed significantly increased KDR (+) cells, in contrast to CD34, CD31, and VE-Cadherin (+) cells. In response to simvastatin, IL-8 was mainly increased in monocyte culture supernatants while VEGF increased in smooth muscle cell culture supernatants. These cytokines were associated with increased EPC migratory function. The increase in IL-8 secretion from monocytes by statin treatment was associated with phosphorylation and inactivation of GSK3beta, which was reversed by constitutive activation of GSK-3beta.

CONCLUSION

Simvastatin enhances endothelial differentiation of peripheral blood mononuclear cells in patients with hypercholesterolemia and increases pro-angiogenic cytokine IL-8 secretion from monocytes. Our results may explain the pro-angiogenic effects associated with statin therapy and offer further evidence of statin pleiotropism.

Absence of a relationship between immunophenotypic and colony enumeration analysis of endothelial progenitor cells in clinical haematopoietic cell sources

BACKGROUND

The discovery of adult endothelial progenitor cells (EPC) offers potential for vascular regenerative therapies. The expression of CD34 and VEGFR2 by EPC indicates a close relationship with haematopoietic progenitor cells (HPC), and HPC-rich sources have been used to treat cardiac and limb ischaemias with apparent clinical benefit. However, the laboratory characterisation of the vasculogenic capability of potential or actual therapeutic cell autograft sources is uncertain since the description of EPC remains elusive. Various definitions of EPC based on phenotype and more recently on colony formation (CFU-EPC) have been proposed.

METHODS

We determined EPC as defined by proposed phenotype definitions (flow cytometry) and by CFU-EPC in HPC-rich sources: bone marrow (BM); cord blood (CB); and G-CSF-mobilised peripheral blood (mPB), and in HPC-poor normal peripheral blood (nPB).

RESULTS

As expected, the highest numbers of cells expressing the HPC markers CD34 or CD133 were found in mPB and least in nPB. The proportions of CD34+ cells co-expressing CD133 is of the order mPB>CB>BM approximately nPB. CD34+ cells co-expressing VEGFR2 were also most frequent in mPB. In contrast, CFU-EPC were virtually absent in mPB and were most readily detected in nPB, the source lowest in HPC.

CONCLUSION

HPC sources differ in their content of putative EPC. Normal peripheral blood, poor in HPC and in HPC-related phenotypically defined EPC, is the richest source of CFU-EPC, suggesting no direct relationship between the proposed EPC immunophenotypes and CFU-EPC potential. It is not apparent whether either of these EPC measurements, or any, is an appropriate indicator of the therapeutic vasculogenic potential of autologous HSC sources.

Intracoronary infusion of autologous bone marrow cells and left ventricular function after acute myocardial infarction: a meta-analysis

Recent clinical studies have demonstrated that intracoronary infusion of autologous bone marrow cells (BMC) in conjunction with standard treatment may improve left ventricular function after an acute myocardial infarction (AMI). However, the results of these studies remain controversial, as the studies were relatively small in size and partially differed in design. We reviewed primary controlled randomized clinical studies comparing intracoronary transfer of autologous non-mobilized BMC combined with standard therapy versus standard therapy alone in patients with AMI. We identified five randomized controlled clinical trials, three of which were also placebo- and bone marrow aspiration-controlled. Non-mobilized BMC were infused into the revascularized coronary target artery 6.6 +/- 6.1 days after AMI. The mean follow- up period of 5.2 +/- 1.1 months was completed by 482 patients, 241 of which received infusion of BMC. The effect of BMC on left ventricular ejection fraction (LVEF) as a major functional parameter was evaluated. Analyzing the overall effect on the change in LVEF between baseline and follow-up value revealed a significant improvement in the BMCtreated group as compared to the control group (P = 0.04). Thus, considering the increase in LVEF during follow-up, transplantation of BMC may be a safe and beneficial procedure to support treatment of AMI. However, the functional improvement observed with this form of therapy was altogether relatively moderate and the studies were heterogeneous in design. Hence, further efforts aiming at large-scale, double-blind, randomized and placebo-controlled multi-center trials in conjunction with better definition of patients, which benefit from BMC infusion, appear to be warranted.