Circulating CD34⁺ progenitor cells and growth factors in patients treated with PCI for acute myocardial infarction or stable angina pectoris.

OBJECTIVE: To differentiate the effect of myocardial infarction from the effect of percutaneous coronary intervention (PCI) on the circulatory profiles of CD34(+) cells and growth factors in patients with ST-elevation myocardial infarction (STEMI). METHODS: Twenty patients with STEMI and 10 with angina pectoris (AP) were included. All were treated with PCI. Blood was drawn before PCI in the AP group, and after 3 and 12 hours, and 1, 3, 5, 7 and 14 days after PCI in both groups. In STEMI patients, correlation analyses between TIMI myocardial perfusion grade (TMP-grade) and circulating CD34(+) cells were also assessed. RESULTS: Circulating CD34(+) cells increased from day 1 to days 5 and 7 after PCI only in STEMI patients (p < 0.05). Between-group analyses revealed a borderline significant difference in change in SDF-1α concentrations from 3 h to 14 days after PCI (p = 0.05), and SDF-1α was significantly higher in STEMI patients 14 days after PCI (p < 0.05). In both groups, peak HGF concentrations were observed 3 h after PCI, whereas IGF-1 increased in AP patients only, 3 h after PCI (p < 0.005). TIMI perfusion grade was negatively correlated to the circulating number of CD34(+) cells 5 days after PCI (r =-0.69, p < 0.005). CONCLUSION: After PCI, STEMI patients have significantly higher numbers of circulating CD34(+) progenitor cells compared to patients with AP. STEMI results in a significant increase in SDF-1α after 14 days, and the increase at this time may indicate a favorable environment for progenitor cell therapy.

Using global gene expression patterns to characterize Annexin V positive and negative human monocytes in culture.

OBJECTIVE: To investigate the early apoptosis that may be detected by Annexin V binding to phosphatidylserine and propidium iodide (PI) exclusion in human monocytes. When studying monocytes in culture, less than 40 % of these cells survive after 7 days. MATERIAL AND METHODS: In the first 4 h, 24 % of monocytes in culture develop into Annexin V(+)/PI(-) cells. Human monocytes were investigated at 0 h and sorted into Annexin V(+) and Annexin V(-) by FACS after 4 h. Gene expression was examined by microarray analyses. RESULTS: At 4 h, Annexin V(+) monocytes versus Annexin V(-) cells showed 1220 differentially expressed genes. Ingenuity Pathway Analysis disclosed 153 genes related to cell death. Among these were caspase activators, caspase 6, Apaf 2 and FAS, as well as the autophagy gene ATG5. In addition, examination of the most up-regulated or down-regulated genes among the 1220 revealed genes involved in other biological processes, as well as genes not yet annotated. These included the non-annotated genes LOC28480 (fold change: 82) and 225767-at (fold change: 68) and the transcription factor SOX 4 (fold change: 24). conclusions: We suggest that apoptosis in cultured monocytes, as evidenced by Annexin V(+), operates through genes well known in apoptosis, but that the process also involves additional genes not commonly associated with apoptosis.

Flow cytometry-sorted non-viable endotoxin-treated human monocytes are strongly procoagulant.

Monocytes/macrophages are important in disease states such as gram-negative sepsis and coronary artery disease. Following exposure to lipopolysaccharide (LPS), monocytes express tissue factor (TF), the main initiator of blood coagulation. We previously demonstrated that human monocytes treated with high concentrations of LPS, or with LPS and calcium ionophore, displayed higher TF activity than monocytes treated with only low concentrations of LPS, even though the monocytes under all conditions expressed similar amounts of cell surface TF antigen. Such restrainedTF activity is often referred to as encryption and its release as de-encryption. We also observed that the increase in TF activity, de-encryption, coincided with an increase in cell surface phosphatidylserine (PS) representing apoptosis and necrosis. In the present work, we separated LPS and LPS and calcium ionophore-treated human monocytes into two populations, one of mainly viable, PS negative cells, and one of mainly non-viable, PS positive cells, by sorting flow-cytometry. We observed that non-viable cells expressed considerably less TF antigen than viable cells. Despite this, non-viable cells were clearly more procoagulant than viable cells in two different coagulation assays. Procoagulant activity was dependent on both TF and PS. We consider the higher content of externalized PS in non-viable monocytes as the major reason for the stronger procoagulant activity of these cells. Thus, TF de-encryption appears largely to occur on PS positive, non-viable cells under these conditions. This supports the important role of PS in coagulation, and it suggests that PS expression signifying cell death, may be clinically relevant.

Response of malignant B lymphocytes to ionizing radiation: gene expression and genotype.

The human malignant B-lymphocyte cell lines Reh and U698 show arrest in G2 phase after ionizing radiation (IR), but only Reh cells arrest in G1 phase and die by apoptosis. We have used cDNA microarrays to measure changes in gene expression at 2, 4 and 6 hr after irradiation of Reh and U698 cells with 0.5 and 4 Gy in order to begin exploring the molecular mechanisms underlying the phenotypic changes. We also investigated whether gene expression changes could be caused by possible aberrations of genes, as measured by comparative genomic hybridization. Reh cells showed upregulation of CDKN1A that likely mediated the G1 arrest. In contrast, U698 cells have impaired function of TP53 protein and no activation of CDKN1A, suppressing the arrest in G1. The G2 arrest in both cell lines was likely due to repression of PLK1 and/or CCNF. IR-induced apoptosis in Reh cells was probably mediated by TP53 and CDKN1A, whereas a high expression level of MCL1, caused by gene amplification, and activation of the NFKB pathway may have suppressed the apoptotic response in U698 cells. Genes suggested to be involved in apoptosis were activated long before this phenotype was detectable and showed the same temporal expression profiles as genes involved in cell cycle arrest. Our results suggest that differences in functionality and/or copy number of several genes involved in IR-regulated pathways contributed to the phenotypic differences between Reh and U698 cells after IR, and that multiple molecular factors control the radiation response of malignant B lymphocytes.