Combined intermittent hypoxia and surface muscle electrostimulation as a method to increase peripheral blood progenitor cell concentration

Background: Our goal was to determine whether short-term intermittent hypoxia exposure, at a level well tolerated by healthy humans and previously shown by our group to increase EPO and erythropoiesis, could mobilizehematopoietic stem cells (HSC) and increase their presence in peripheral circulation. Methods: Four healthy male subjects were subjected to three different protocols: one with only a hypoxic stimulus (OH), another with a hypoxic stimulus plus muscle electrostimulation (HME) and the third with only muscle electrostimulation (OME). Intermittent hypobaric hypoxia exposureconsisted of only three sessions of three hours at barometric pressure 540 hPa (equivalent to an altitude of 5000 m) for three consecutive days, whereas muscular electrostimulation was performed in two separate periods of 25 min in each session. Blood samples were obtained from an antecubital vein on three consecutive days immediately before the experiment and 24 h, 48 h, 4 days and 7 days after the last day of hypoxic exposure. Results: There was a clear increase in the number of circulating CD34+ cells after combined hypobaric hypoxia and muscular electrostimulation. This response was not observed after the isolated application of the same stimuli. Conclusion: Our results open a new application field for hypobaric systems as a way to increase efficiency in peripheral HSC collection

Enhancement of gene transfer with recombinant adeno-associated virus (rAAV) vectors into primary B-cell chronic lymphocytic leukemia cells by CpG-oligodeoxynucleotides.

OBJECTIVE: Transduction of primary B-cell chronic lymphocytic leukemia (B-CLL) cells with recombinant adeno-associated virus (rAAV) vectors is dependent on preactivation of leukemic cells by CD40L. CpG-oligodeoxynucleotides (CpG-ODNs) are able to activate cytokine production and proliferation of B-CLL cells. Therefore CpG-ODNs were tested for their potential to enhance transgene expression in CLL cells. MATERIALS AND METHODS: Using an optimized adenovirus-free packaging system, rAAV vectors coding for the enhanced green fluorescent protein (AAV/EGFP) were packaged and highly purified resulting in infectious titers up to 5 x 10(9)/mL. Cells obtained from patients with B-CLL were infected with AAV/EGFP at a multiplicity of infection of 100 while being stimulated with CpG-ODNs and/or CD40L-expressing HeLa/SF cells. Transgene expression was assessed after 48 hours by flow cytometry. RESULTS: Stimulation of B-CLL cells by CpG-ODNs resulted in up-regulation of costimulatory molecules and G(1)/S-phase transition at similar levels compared to activation by HeLa/SF cells, but use of CpG-ODNs alone did not result in any efficient AAV/EGFP transduction. Combined stimulation of B-CLL cells with HeLa/SF cells and CpG-ODNs during AAV/EGFP transduction significantly enhanced transgene expression compared to feeder stimulation alone (p=0.004). In addition, the copy number per single cell was significantly increased by addition of CpG-ODNs as detected by quantitative real-time PCR (p=0.04). Use of self-complementary AAV vectors that are not dependent on target cell DNA synthesis did not result in increased transgene expression compared to single-stranded AAV vectors (p=0.30). CONCLUSION: Stimulation by CD40L is crucial for efficient gene transfer into B-CLL cells by rAAV vectors, whereas transduction efficiency can be significantly enhanced by CpG-ODNs

Mobilization of stem and progenitor cells in cardiovascular diseases

Circulating bone marrow (BM)-derived stem and progenitor cells (SPCs) participate in turnover of vascular endothelium and myocardial repair after acute coronary syndromes. Acute myocardial infarction (MI) produces a generalized inflammatory reaction, including mobilization of SPCs, increased local production of chemoattractants in the ischemic myocardium, as well as neural and humoral signals activating the SPC egress from the BM. Several types of circulating BM cells were identified in the peripheral blood, including hematopoietic stem cells, endothelial progenitor cells, mesenchymal stromal cells, circulating angiogenic cells and pluripotent very small embryonic-like cells; however, the contribution of circulating cells to the myocardial and endothelial repair is still unknown. The number and function of these cells is impaired in patients with diabetes and other cardiovascular risk factors, but can be improved by physical exercise and use of statins. The mobilization of SPCs in acute coronary syndromes and stable coronary artery disease seems to predict the clinical outcomes in selected groups of patients. Interpretation of the findings has to incorporate other factors that modulate the process of mobilization, such as coexisting diseases, age and medications. This review discusses the mobilization of SPCs in acute ischemia (MI, stroke), as well as in stable cardiovascular disease, and highlights the possibility of using the SPC as a marker of cardiovascular risk