ABSTRACT
BACKGROUND: There still was not any report about inducing stem cells into matured cells to form products in vitro.OBJECTIVE: To induce CD34+ cells of umbilical cord blood to differentiate into mature megakaryocytes, and to investigate the mechanism of production of platelets.DESIGN, TIME AND SETTING: This cytology in vitro study was conducted at the Central Laboratory of Xiangya Hospital and Xiangya Third Hospital from 2004 to 2006. MATERIALS: Umbilical cord was collected from healthy full-term pregnant puerperants at the Xiangya Hospital.METHODS: The CD34+ cells were isolated from umbilical cord blood by magnetic activated cell sorting (MACS) and then cultured in 24-well culture plate at 5x107/L in StemPro-34 serum-free medium, supplemented with L-glutamine, saturated human transferrin, CaCl2, insulin, deionized bovine serum albumin and recombinant human thrombopoietin at 37℃, under 0.05 volume fraction CO2 saturated humidity to be differentiated into megakaryocytes for 14-21 days. Cell medium was absorbed, and centrifuged to obtain supernatant. Samples were centrifuged again, and then supernatant was removed. The remaining was platelet-like particles in cell culture plate. Platelet was isolated from normal platelet-rich plasma.MAIN OUTCOME MEASURES: The following parameters were measured: morphological changes in cultured cells and platelet-like particles in supematant; results of immunohistochemistry; observation results under a microscope; platelet aggregation; CD41 expression.RESULTS: At day 10, silk-like substances were found in megakaryocyte culture medium, with the presence of platelet-sized particles. The production of platelet-sized particles reached a peal at day 16. Cultured cells were strongly positively for platelet-specific antigen GP Ⅱb Ⅲa. Under the optical microscope, mature megakaryocytes were detected, with the presence of some immature megakaryocytes, and platelet-sized particles were found surrounding megakaryocytes. Under the electron microscope, a majority of mature megakaryocytes and a few apoptotic megakaryocytes were detected, and platelet-sized particles in the supernatant had the same size and structure with the platelet in the platelet-rich plasma. Some platelet surfaces were smooth or irregular. Platelet-sized particles in the supematant aggregated in response to thrombin as platelets in normal platelet-rich plasma. Flow cytometry demonstrated that the cultured platelets had the same high expression rate of CD41 as the platelets from platelet rich plasma.CONCLUSION: Umbilical cord blood CD34+ cells can be induced to differentiate into pudfied and mature megakaryocytes and platelets in vitro.
ABSTRACT
OBJECTIVE@#To determine the expression of DLK1 gene in acute leukemias (AL) and its function in erythroid differentiation of K562 cells.@*METHODS@#We detected the expression of DLK1 gene in 65 different acute leukemia categories (a test group) and 34 normal bone marrow controls (a control group) with RT-PCR. DLK1 protein in 20 out of the 65 AL patients and 13 of the 34 controls was assayed by Western blot. The K562 cell line was induced to erythroid differentiation by hemin. We observed the relationship between its expression and erythroid differentiation.@*RESULTS@#Both leukemia cells and normal marrow cells expressed DLK1. The expression of DLK1 mRNA in patients in the test group was higher than that in the control group (P=0.018), while there was no significance between acute lymphoblastic leukemia and acute myelogenous leukemia (P>0.05).The expression of DLK1 mRNA in the test group at onset had no relation with the WBC and platelet count in the total peripheral blood, and the same was true for blast cell rates in bone marrow cells.The level of DLK1 protein in the test group was higher than that in the control group, which was consistent with the mRNA expression (P=0.042). The expression of DLK1 mRNA decreased gradually with K562 cells towards hemin-induced erythroid differentiation.@*CONCLUSION@#DLK1 gene may be involved in leukemia,but the mRNA level of DLK1 has no relation with some clinical characteristics of AL patients at onset. DLK1 may inhibit the erythroid differentiation of K562 cells.
Subject(s)
Adolescent , Adult , Aged , Child , Child, Preschool , Female , Humans , Male , Middle Aged , Young Adult , Acute Disease , Calcium-Binding Proteins , Case-Control Studies , Cell Differentiation , Genetics , Cell Transformation, Neoplastic , Genetics , Erythroid Cells , Pathology , Erythroid Precursor Cells , Pathology , Intercellular Signaling Peptides and Proteins , Genetics , Metabolism , K562 Cells , Leukemia , Genetics , Metabolism , Membrane Proteins , Genetics , Metabolism , RNA, Messenger , Genetics , MetabolismABSTRACT
0 5).Conclusions The measurement of platelet membrane GPⅡbⅢa complexes by FCM can provide a simple, sensitive and reliable method for G T diagnosis,and also can be applied to analysis of GT family pedigree.