This paper elaborates the specific implementation process of the "research-based learning" teaching reform of genetic experiment in medical undergraduate education, including the change of teaching philosophy among teachers, the integration and expansion of experimental contents, the innovation of classroom-teaching model, the compilation of proper textbook, the update of assessment methods and the establishment of evaluation mechanism for teaching and so on. Preliminary research shows that RBL teaching reform can stimulate medical students' interest and potential in learning, and improve their practical and scientific research innovation ability.

BACKGROUND: Some limitations involving drug therapies and surgical treatment exist in the traditional treatment of osteogenesis imperfecta. In recent years, a growing number of scientists attempt to treat osteogenesis imperfecta by mesenchymal stem cells transplantation. OBJECTIVE: To summarize the mesenchymal stem cell treatment of osteogenesis imperfecta to guide relevant animal experiments, thereby promoting its clinical application. METHODS: A computer‐based online search of PubMed between January 2000 and June 2018 was performed to search related articles with the keywords of “osteogenesis imperfecta, stem cells, mesenchymal stem cells, stem cells therapy, stem cells transplantation” in English. Literatures regarding mesenchymal stem cells for treatment of osteogenesis imperfecta were selected; in the same field, the articles published lately in authoritative journals were preferred. RESULTS AND CONCLUSION: Mesenchymal stem cells can directly differentiate into functional cells or exert paracrine effect to repair bone defects caused by osteogenesis imperfecta. The low immunogenicity and immunomodulatory capacity of mesenchymal stem cells ensure the transplantation safety in the treatment of osteogenesis imperfecta. Mesenchymal stem cells can fundamentally treat osteogenesis imperfecta, and do not produce adverse reactions that are unavoidable in the drug treatment, which have broad application prospects. Although there are currently no systematic criteria for the efficacy and safety of mesenchymal stem cells in the treatment of osteogenesis imperfecta, mesenchymal stem cell transplantation can circumvent the limitations of conventional drugs and surgical treatment. Further studies are expected to improve the treatment of osteogenesis imperfecta using mesenchymal stem cells and promote its clinical applications, as cell transplantation indeed benefits the patients. Funding: the National Key R&D Program of China, No. 2017YFC1001904; Tianjin City Science and Technology Support Program, No. 16YFZCSY00900

目的 探究羟基磷灰石(HA)对脂肪来源的间充质干细胞(ADSCs)向成骨分化的影响.方法 分离、纯化并鉴定C57BL/6小鼠的ADSCs,将HA与ADSCs共培养,CCK-8法检测不同浓度(0、5、10、20、50、100、500 mg/L)的HA对ADSCs增殖的影响;碱性磷酸酶(ALP)染色检测不同浓度HA对ADSCs成骨分化的影响;实时荧光定量逆转录-聚合酶链反应(qRT-PCR)检测ADSCs成骨相关基因骨钙素(BGLAP)、碱性磷酸酶(ALP)、Ⅰ型胶原(COL1A1)、骨桥蛋白(OPN)、Runt相关转录因子2(Runx2)的mRNA表达情况.结果 低浓度HA(≤20 mg/L)对ADSCs增殖的影响较小,随着HA浓度增加,细胞的增殖活性下降.HA与ADSCs共培养可显著增加其ALP活性,并促进成骨相关基因的表达(P<0.01),且HA为20 mg/L时诱导效果较好.结论 HA具有诱导ADSCs向成骨细胞分化的能力,为两者混合制作成新的骨支架修复材料提供了理论基础.

Objective To explore the role of LSEC on T cell tolerance. Methods T cell apoptosis, cytokine( IL-2 , IL-4 and IL-10 ) expression and secretion of human T cells activated by CD3/CD28 alone and mixed-cultured with human LSEC were detected. Results The ratio of cell apoptosis was higher in mixed-cultured T cells than T cells alone. The gene expressions of IL-4 and IL-10 were higher in mixed-cultured T cells than T cells alone, while gene expression of IL-2 had no significant difference in mixed-cultured T cells than T cells alone. The cytokine se-cretion of IL-2, IL-4 and IL-10 was consistent with gene expression. Conclusion LSEC could induce T cell toler-ance by decreasing T cell number and altering cytokine secretion.

Objective To establish a method for the induction and amplification of regulatory dendritic cells ( DCreg) derived from mouse bone marrow in vitro, and to identify their biological and functional characteristics.Methods The bone marrow mononuclear cells ( BM-MNCs) were induced to differentiate into DCreg by recombinant mouse IL-4 and re-combinant murine granulocyte-macrophage colony-stimulating factor ( rmGM-CSF ) .The cells collected on the sixth day contained a large number of DCreg.A portion of cells were cultured with lipopolysaccharide ( LPS) for another 2 days to a-chieve the mature DC (mDC).The morphology of DCreg was observed by inverted microscope.The expression of CD40, CD11b and CD86 were detected by flow cytometry.The splenic CD8 +T cells were randomly divided into three groups:groups A, B and C.The cells in the group A and group B were incubated with DCreg or mDC at different ratios (5:1, 10:1, 20:1) of mixture to culture for 4 days, and cells in the group C were not treated.We detected the proliferation of CD8 +T cells by the CFSE labeling.The expression of perforin ( Prf1) and GzmB mRNA in CD8 +T cells was detected by real-time PCR.Results Freshly isolated MSCs were round with small volume.When induced for 6 days, much more cell colonies were found, and cells became larger with the increased cell surface projections.The positive cell percentage of CD11b was (96.1 ±2.7)%.Compared with mDC, the positive expression rates of CD40 and CD86 in DCreg were lower (all P<0.05).Compared with group B, the proliferation rate of group A was significantly decreased (all P<0.05). Compared with group C and group B, the expression of Prf1, GzmB mRNA of group A was reduced (all P<0.05).Com-pared with group C, the expression of GzmB mRNA in the group B was increased (all P<0.05).Conclusions rmGM-CSF combined with rmIL-4 can induce the differentiation of BM-MNCs into DCreg successfully, which can obtain a large number of highly purified DCreg with immune suppressive function.

Objective To explore the immunomodulation property of bone marrow-derived mesenchymal stem cells (BMSCs) from Sprague-Dawley (SD) rats after they are isolated, cultured and identified by surface marker and differentiation potential examination. Methods BMSCs were isolated from femur and tibia of SD rats and passaged by trypsinization. The surface markers of the 3rd passage BMSCs were detected by flow cytometry and the capacity of their adipocyte and cartilage differentiation were examined. In order to explore the immunomodulation property of BMSCs, allogeneic spleen T cells of Wi?star rats were co-cultured with BMSCs through either cell-to-cell contact or transwell, then its effect on the T cell subsets and related mechanism was also examined. Results BMSCs were mainly spindle-shaped in culture. Surface marker detec?tion showed that BMSCs expressed high levels of CD29, CD44 and CD90 but no CD34 nor CD45 at the third generation. Un?der specific condition, BMSCs could differentiate into adipocytes and chondrocytes. The CD8+effector T cells (Teffs) decreas?es effectively and the CD4+CD25+regulatory T cells (Tregs) increased remarkably when BMSCs were co-cultured with allo?geneic spleen T cells for 48 hours. The expressions of IL-10 and TGF-β1 of BMSCs significantly increased after co-culture with T cells, and this effect was more obvious in cell-to-cell contact group. Conclusion The immunomodulation property of BMSCs were presumably function through cell-to-cell contacts and cytokine secretion.