Identification and in vitro BrdU labeling of adult bone marrow mesenchymal stem cells / 中国组织工程研究

ABSTRACT

BACKGROUND: No particular marker molecule of bone marrow mesenchymal stem cells (BMSCs) is presently found, so its determination is difficult. BrdU marker has no radioactive pollution. Some studies have confirmed that BrdU marker has no damage to cell function without ultraviolet radiation. OBJECTIVE: To investigate in vitro identification and labeling methods and biological characteristics of adult BMSCs. DESIGN, TIME AND SETTING: The cell experiment was conducted at the General Hospital of Lanzhou Military Area Command of Chinese PLA between June and December 2007. MATERIALS Bone marrow was collected from 5 healthy adult volunteers. BrdU was purchased from Sigma, USA. METHODS: 10 mL adult bone marrow was harvested to isolate mononuclear cells by density gradient. Cells were cultured in DMEM containing 10% fetal bovine serum and proliferated at a density of 2?108 L-1. At the third passage, BMSCs was inoculated in medium supplemented with osteoblast inductor and stained with alkaline phosphatase. Subsequently, BMSCs were inoculated in medium supplemented with lipoblast inductor and stained with oil red O. Cells were incubated with BrdU at different concentrations of 5, 10 and 15 ?mol/L for 12, 24, 48, 72 and 96 hours, and then detected by immunocytochemistry. MAIN OUTCOME MEASURES: Cell growth and proliferation were observed under an inverted light microscope. Cell phenotype, osteoblast and lipoblast differentiation were identified by flow cytometry. BrdU-positive labeling rate and cell growth after labeling were investigated. RESULTS: In vitro cultured BMSCs were homogenous population and exhibited a spindle-shaped fibroblastic morphology. BMSCs expressed CD44 and CD71, but did not express CD34 and HLA-DR. BMSCs can differentiate into osteoblasts and lipoblasts. Most BMSCs were labeled by BrdU. With the increase in labeling concentration and over time, BrdU positive rate gradually increased and exceeded 90% after labeling with BrdU (10 ?mol/L) for 72 hours, with the labeling identifiable in nine consecutive passages. At the third passage, 90% BMSCs were in G0/G1 phase, and 88.62% in G0/G1 phase after labeling. BrdU has little effect on morphous and proliferation of labeled cells. CONCLUSION: Adult BMSCs can be identified through morphological character, specific surface antigens and multipotential differentiation in vitro. BrdU labeling provides a feasible means for a dynamic observation of the survival, growth and differentiation of the implanted BMSCs. The optimal dosage and timing of BrdU labeling are respectively 10 ?mol/L and 72 hours.