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BACKGROUND: It is important to study the methods of culturing bone marrow-derived mesenchymal stem cells (MSCs) to obtain a great amount of high purity MSCs for applying ocular tissues constructed by tissue engineering technique to treat eye diseases.OBJECTTVE: To separate and culture in vitro MSCs from bone marrow of the adult rats by density gradient centrifugation combined with adherence culture, and observe the growing characteristics and the possibility of mass multiplication.DESIGN: A completely randomized grouping design/repetitive measuring experiment.SETTING: Pathological laboratory, Zhongshan Ophthalmic Center, Sun Yat-sen University.MATERIALS: Four six-week-old SD rats about 250 g, grade Ⅱ of cleaning, were provided by the Animal Center of Sun Yat-sen University [certificate number: SCSK(Yue)2004/0011], about 250 g each rat and there was no limit to the sex. The main reagents and instruments included low sugar Dulbecco modified Eagle culture medium (DMEM/F12, American Gibco Corporation), trypsin (fetal bovine serum (FBS, Hangzhou Sijiqing Bio-Engineering Material Research Institute), American Gibco Corporation), disodium edetate, lymphocyte separating medium, fibronectin, CD44, CD34, CD31 monoclonal antibodies, two-step-method kit for immunohistochemistry (Beijing Zhong shan Biotechnology Corporation).METHODS: This experiment was conducted at the Key laboratory of Ophthalmology (Sun Yat-sen University), Ministry of ethanol (750 g/L) for 10 minutes. Under aseptic condition, the medullaris cavitas was exposed, the syringe containing application m edium was directly punctured into the femoral cavity, the cells in the medullaris cavitas were washed out with the culture medium containing heparin and taken as the cell suspension. The bone marrow-derived MSCs were separated and purified by density gradient centrifugation combined with adherence culture, and the growing conditions of the wells. When the cells had generally connected with each other, they were fixed with methanol or dimethy ketone in situ for 10 minutes, and then hematoxylin eosin (HE) staining or immunohistochemical staining. Antibodies against fiinoculated to 96-well culture plate by a cell density of 4.25×107/L, with 200 μL every well; then put the culture plate into culture box. Then from the next day to the sixth day, 5 g/L MTT solution was added into two rows (20 μL every well) every day, continuously cultured for 4 hours, then the supernatant was removed, and 200 μL DMSO was added to each well, agitated for 5 minutes, then detected the absorbance (A) values at 570 nm wave length, and a growth curve was drawn.branes were clear and the cell bodies were lucent. Being cultured for 2 days, there appeared adherent cells. 3 days later,most of the adherent cells extended and appeared to be in polygon, star or long-shuttle shapes. 4 days later, the cells showed to be in division growth stage; and about 12 days later, the cell clones were connected to each other, appearing curve of subcultured MSCs was in S shape. Cells began growing fast on the 2nd day after being passaged, and they entered the growth period for 3-4 days followed by saturation period, and then cells stopped growing.CONCLUSION: It is a simple and practical method to separate MSCs from the bone marrow of adult rats by means of density gradient centrifugation and adherence. MSCs can greatly proliferate in vitro and offer seed cells for the application of tissue engineering technique to treat eye diseases.