Proliferation Of Lymphatic Cells Research Articles

Adenosine inhibits the proliferation of lymphatic endothelial cells

Background: The presence of a lymphatic system in the human heart has been demonstrated several decades ago. After myocardial infarction, lymphatic vessel density increases, predominantly in the myocardium, but also in the epicardium and endocardium of both ventricles and atria. The biological relevance of this increase is poorly known. Recent studies suggest that it may be a protective element in the response to myocardial injury, through efficient removal of cellular debris produced by cardiomyocyte death. Adenosine has the potential to stimulate cardiac repair, partly through activation of angiogenesis. However, whether adenosine affects the lymphatic system is unknown. Methods: Human adult dermal microvascular lymphatic endothelial cells (HMVEC) were used to study the direct effect of adenosine on the lymphatic system. Expression of adenosine receptors was investigated using quantitative PCR. Proliferation of lymphatic cells was measured using CyQUANT and Ki-67, migration of the cells was assessed using a wound healing assay and a Boyden chamber assay, and tube formation was evaluated using a tubulogenesis assay in collagen and spheroids matrix. Cytotoxicity was evaluated using the Live/Dead viability/cytotoxicity assay. Lymphangiogenesis was characterized ex vivo using mouse lymphatic ring explants. To identify potential paracrine effects of adenosine on lymphangiogenesis, the murine cardiomyocyte cell line HL-1 and the human fibroblast cell line 1226 KI were used. Results: HMVEC expressed A2A and A2B, but not A1 and A3, adenosine receptors. Adenosine dose-dependently decreased the proliferation of HMVEC (-40% for 10 μmol/L adenosine), and inhibited their migration and tube formation. Adenosine also decreased microvessel outgrowth from lymphatic rings explanted from mouse lymphatic thoracic duct. A potential cytotoxic effect of adenosine was ruled out. Adenosine decreased the production of vascular endothelial growth factor C (VEGFC), the main growth factor of lymphatic endothelial cells, by fibroblasts. Conditioned medium from fibroblasts treated with adenosine inhibited the proliferation of HMVEC. Adenosine did not alter the production of VEGFC by cardiomyocytes. Conclusion: We have shown for the first time that adenosine down-regulates lymphangiogenesis. This observation may be important for the design of adenosine-based therapies to stimulate cardiac repair.

Staphylococcal Lipoteichoic Acid Exerts Growth Factor — Like Activity Towards Human and Murine Cells

Lipoteichoic acid (LTA) was extracted from Staphylococcus saprophyticus strain S1 and tested for the capacity to induce hematopoietic and lymphatic cell proliferation. As compared to nontreated cells, the number of human bone marrow cells significantly increased in the presence of low LTA concentrations. Optimal growth was observed on the fifth day of in vitro incubation. After exposure to LTA, the lymphocyte proliferation rate also increased in a dose and time dependent manner. On the other hand, human epithelial cells and fibroblasts did not show enhanced growth activities in the presence of LTA.

The benign monoclonal gammapathies: a study of monoclonal antibodies.

Very few clinical conditions have received so many names as the one treated here (Waldenström 1970 b). This is obviously an indication of the fact that the exact nosologic position seems difficult to define. The present author introduced the term benign monoclonal gammapathy (BMG) and still thinks that this is suitable when we want to describe what is really important (Waldenström 1968). I chose the expression gammapathy in order to indicate that the pathologic process was connected with the formation of gammaglobulins in the wide sense of the word. Osserman prefers the term plasmacellular dyscrasia. This has many advantages, but on the other hand I should like to stress the fact that both the lymphomas and the plasmocytomas may be involved. The fact that proliferation of lymphatic cells is a characteristic of the condition macroglobulinemia with formation of IgM means that the word plasmacellular does not cover the whole field. There has been much discussion regarding the term benign. This seems hard to understand, as the central implication of the term BMG is connected with the fact that it is not malignant or progressive like myeloma or clinical macroglobulinemia. Recently, Kyle has published an excellent review of the experiences from the Mayo Clinic (Kyle 1978) and he prefers the expression of undetermined significance as more appropriate than benign. The present paper will try to convey the impression that benign is the most important part of the term. It is the key word as it indicates that no treatment should be given.