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Human umbilical cord blood (CB) is a recognized source of hematopoietic tissues for transplantation, the treatment of malignancies and gene therapy, among other potential clinical applications. A rich network of hematopoietic cytokines and growth factors possessing stimulatory effects on primitive hematopoietic stem/progenitor cells further characterizes fetal CB. To better elucidate these complex interactions and properties, we compared the hematopoietic activities of CB and normal human peripheral blood (PB), by examining growth/survival of normal hematopoietic progenitors and erythropoietin-dependent UT-7/EPO cells. Colony-forming activity assays of normal bone marrow (BM) BFU-E and CFU-GM showed that CB significantly enhanced progenitor cell growth in comparison to PB. Apoptosis was determined by enumerating APO 2.7 mAb stained cells using flow cytometry. UT-7/EPO cell cultures subjected to PB exhibited a four-fold higher rate of apoptosis than CB exposed cultures, indicating that CB markedly suppressed apoptosis in this human leukemic cell line. Immunoprecipitation of UT-7/EPO cell lysates and immunodetection of the anti-phosphotyrosine Ab (4G10), revealed that CB induced tyrosine phosphorylation of three proteins, with approximate molecular masses of 160, 117.5 and 80 kDa. The 80 kDa protein corresponds to the previously reported molecular mass for the Epo receptor, suggesting that erythropoietin is enriched in CB compared with adult PB.

Biological effects of extremely low-frequency electromagnetic fields (ELF-EMF) on microcirculation were investigated in vivo by monitoring arteriole diameters in conscious mice. Measurements of blood vessel diameter were monitored 33 min non-stop before during and after exposure with ELF-EMF and every 389 ms blood vessel diameter were calculated.Using a dorsal skinfold chamber (DSC), and following caudal vein injection of FITC-dextran 250 kDa, the microvasculature (initial arteriole diameter of 45-80 µm), was examined by intravital microscopy and video images were recorded for a total time of 33 min. Arteriole diameter was continuously measured by on-line analysis using a High-speed Digital Machine Vision System CV-2100, using an edge-gap detection algorithm. Since vessel diameters exhibit rhythmic variation expressed by vasomotion, for estimation of microcirculatory activity we used both raw data for frequency analysis of vasomotion (measured frequencies of vasomotion were in the range 0.008 ÷ 0.1 Hz) and evaluate mean blood vessel diameter for each 1 min period of time, and make a comparison between Pre, Exposure/Sham exposure and Post exposure periods, with the aim to evaluate possible changes in mean blood vessel diameter as a result of ELF-EMF action.During EMF exposure and post-exposure periods, arteriole diameters increased significantly compared with the pre-exposure period, and the changes were larger during post-exposure. In contrast to sham exposure, vasodilatation of the microvasculature was significantly greater during exposure and post-exposure to 16 Hz EMF. These findings suggest that ELF-EMF may have potential therapeutic use benefit for treating vascular disorders.

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