BackgroundActivation of immune cells by malaria infection induces the secretion of cytokines and the synthesis of other inflammatory mediators. This study compared the cytokine levels and leukocyte count between malaria-infected peripheral and placental blood of pregnant women before delivery and postpartum. The cytokines assessed include interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), interleukin-4 (IL-4), interleukin-6 (IL-6) and interleukin-10 (IL-10).Materials and methodsThe subjects comprised 144 malaria-infected pregnant women and 60 malaria-infected women at post-partum stage (for placental blood collection). Others were 60 malaria-uninfected pregnant women and 40 malaria-uninfected women at postpartum stage (for placental blood collection). Forty malaria-infected and 40 malaria-uninfected nonpregnant women served as control subjects. The test groups were asymptomatic, and the control groups were apparently healthy subjects. All were aged between 17 and 44 years. Ethical approval for the study was obtained at Abia State University Teaching Hospital and Living Word Mission Hospital, Aba. Informed consent was obtained from the participants. Blood samples were aseptically collected initially from the maternal peripheral circulation and from the placenta on delivery, and tested for HIV and malaria using standard methods. IFN-γ, TNF-α, IL-4, IL-6 and IL-10 were measured by enzyme-linked immunosorbent assay technique. Kruskal–Wallis test was used for comparison of the groups.ResultsIFN-γ was significantly higher in the peripheral than in placental blood (P=0.001). IL-4 and IL-10 were significantly lower in the peripheral than in placental blood (P=0.001 and P=0.004, respectively). The total leukocytes, neutrophils and lymphocyte counts were significantly higher in the placenta than in peripheral blood (P=0.001), and the mixed differential count was significantly higher in the placenta than in peripheral blood (P=0.012).ConclusionThis study has shown that the cytokine levels and leukocyte counts may differ between the peripheral and placental blood of the same women. Therefore, measurement of parameters in the peripheral circulation may not always reflect the levels in the placental blood for the assessment of immune cellular response at the materno–fetal interface.

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For in vitro cultural purposes, cytokines and a variety of other synthetic constituents have been used in time past to support the growth of Hematopoietic Stem Cells (HSCs) and many other critical human cells. However, in the case of HSCs, it has not been possible to ensure their long-term survival and expansion by merely using cocktails of these cytokines. Endothelial Cells (EC), the main type of cells lining the blood vessels, lymphatic vessels and the heart are favorable to HSC growth. When in co-culture with HSCs, ECs have been found to be key in supporting HSCs in vitro. Harvesting sufficient number of endogenous ECs is critical for these cells' utility in experiments and for clinical purposes. The number of natural endogenous ECs obtainable by most current procedures fall short of that required for clinical application and HSC co-culture purposes; hence researchers have now resorted to the use of synthetic brand of ECs which have its own shortcomings. Although good for experimental purposes, it may not be easily adaptable for clinical therapy. This review is intended to blend the current technologies in use for therapy to formulate a procedure for obtaining large numbers of endothelial cells that could be used in co-culture with HSCs or even for use in clinical therapy.

Currently, hematopoietic stem cells derived from the bone marrow or from cord blood are used to treat patients who require hematopoietic stem cell treatment. In spite of the varied sources from which hematopoietic stem cells may be obtained, there is still shortage of genetically matched hematopoietic stem cell grafts. As a result, many patients requiring transplantation cannot benefit from the procedure. Efforts have been made in time past to expand this unique type of adult stem cells in culture, with little success. These stem cells, even in the presence of several exogenous cytokines, serum factors and support from (mesenchymal) cells do not propagate the stem cells beyond a few days. However, reports from recent studies indicate that long-term propagation and large-scale expansion of hematopoietic stem cells is now possible with the use of endothelial cells in co-culture with hematopoietic stem cells. These studies have demonstrated that the presence of endothelial cells is necessary for promoting self-renewal of Hematopoietic Stem Cells (HSC), for long-term survival of repopulating HSCs and for increasing the number of these cells in culture. Endothelial cells from blood vessels constitute the basic building blocks of the human vasculature, being a key constituent of the bone marrow and vascular niche that support hematopoietic mobilization, maintenance and regeneration. Researchers have not only found that endothelial cells could greatly expand HSCs but the proliferation induced by endothelial cells carries no risk of tumor formation. There is a dire need to translate this revolutionary finding from the laboratory into routine clinical use. The purpose of this review therefore, is to glean the several studies related to the subject into a practical protocol scalable for clinical application.