技术资料

Mesenchymal stem cells (MSC) have been extensively studied and gained wide popularity due to their therapeutic potential. Spontaneous transformation of MSC,from both human and murine origin,has been reported in many studies. MSC transformation depends on the culture conditions,the origin of the cells and the time on culture; however,the precise biological characteristics involved in this process have not been fully defined yet. In this study,we investigated the role of p53 in the biology and transformation of murine bone marrow (BM)-derived MSC. We demonstrate that the MSC derived from p53KO mice showed an augmented proliferation rate,a shorter doubling time and also morphologic and phenotypic changes,as compared to MSC derived from wild-type animals. Furthermore,the MSC devoid of p53 had an increased number of cells able to generate colonies. In addition,not only proliferation but also MSC differentiation is controlled by p53 since its absence modifies the speed of the process. Moreover,genomic instability,changes in the expression of c-myc and anchorage independent growth were also observed in p53KO MSC. In addition,the absence of p53 implicates the spontaneous transformation of MSC in long-term cultures. Our results reveal that p53 plays a central role in the biology of MSC. View Publication

The differentiation of eosinophils from hematopoietic precursors and their subsequent maturation,chemotaxis,and activation is primarily regulated by interleukin-5 (IL-5). To examine the effect of chronic IL-5 exposure on hematopoiesis,IL-5 transgenic (IL-5trg) mice and wild-type BALB/c (WT) mice were examined. In comparison to WT mice,a significant alteration in bone marrow hematopoiesis was observed in IL-5trg mice. Although the total number of myeloid progenitors in the bone marrow of IL-5trg mice was not significantly altered,the number of long-term culture-initiating cells (LTC-ICs) was 1.5-fold lower than that observed in WT mice. Furthermore,IL-5trg mice failed to demonstrate hematopoietic activity in long-term bone marrow cultures,which correlated with a significant decrease in the number of bone marrow mesenchymal/stromal progenitor (MSP) cells in these mice. In comparison to WT mice,a 10-fold decrease was observed in the number of fibroblast colony-forming units (CFU-Fs) in IL-5trg bone marrow. Hematopoietic activity of IL-5trg bone marrow cells was rescued by cultivation on preestablished layers of bone marrow-derived stromal cells. However,in contrast to bone marrow,increased hematopoietic activity was observed in the spleen and peripheral blood of IL-5trg mice. Likewise,the numbers of LTC-ICs and granulocyte-macrophage,macrophage,eosinophil,B-lymphocyte progenitors in the peripheral blood and spleen of IL-5trg mice were approximately 20-fold higher than in WT mice. A significant increase in CFU-F numbers was also observed in the spleens of IL-5trg mice compared with WT mice. Overall,our results suggest that constitutive overexpression of IL-5 can potentially induce colonization of spleen with MSP cells,which provides the necessary microenvironment for establishment of hematopoiesis in extramedullary sites. View Publication