Objective To explore the biocompatibility of poly(lacticacid/glycolic acid/asparagic acid-co-polyethylene glycol) biomaterials (PLGA-ASP-PEG) and biological behaviors of cultured marrow stroml stem cells (MSCs) combined with this new type of scaffold in tissue engineering. Methods The PLGA-ASP-PEG tri-block copolymers were obtained through bulk ringopening copolymerization method.MSCs were isolated from the bone marrow of 4 week old New Zealand rabbits. The 3rdgeneration MSCs were cultured combining with PLGA-ASP-PEG in vitro, while cells cultured in PLGA as control group. The cell adhesion rate and the adhesivepower were examined by conventional precipitation method and micropipette aspiration technique respectively. The morphological features were studied by scanning electron microscope. The proliferation behavior of the cells was analyzed by MTT assay. The cell cycle, proliferation index, DNA index and apoptosis of the cells were detected by flow cytometry. The synthesis of protein and collagen were examined by Coomassie Brilliant Blue dyes and 3H-Proline incorporation test. Results The MSCs adhered and grew well on the surface of the biomaterial PLGA-ASP-PEG. The powers of cell adhesion, proliferation and protein and collagen synthesis of the cells were all significantly higher than those of PLGA group (P＜0.05), but the apoptosis rate was significantly lower than that of PLGA group (P＜0.05). The DNA indexes showed the cells of both PLGA-ASP-PEG group and PLGAgroup were normal diploid cells. Conclusion PLGA-ASP-PEG showedgood biocompatibilityand the biological properties improved greatly compared with the PLGA scaffold materials. These results demonstrated that the promise of PLGAASPPEG canbe used as an ideal scaffold material for construction of tissue engineered bone to restore bone defects in bone tissue engineering．
Objective To investigate the effect of nidus vespae on lymphocyte blastisation in mixed culture system of lymphocyte and pancreatic islet. Methods Solution of nidus vespae was extracted with ethanol from its herb. Rat lymphocyte and pig pancreatic islet were isolated and then were mixed together and cultured in incubators of 37 ℃ (concentration in volume: 5%CO2). Three different concentrations of extracted solution of nidus vespae （experimental group Ⅰ: 4.0 g/ml, group Ⅱ: 0.4 g/ml, group Ⅲ: 0.2 g/ml） were added to the mixed culture system of lymphocyte, respectively. Radioactive nuclide counts per minute were measured by 3H-thymdine test in order to examine the role of nidus vespae in inhibiting blatisation of lymphocyte, and the results were also compared with control group and CsA group, respectively. Results The counts were all reduced significantly (P＜0.001) in 3 experimental groups compared with control group (group Ⅰ 45.3%, group Ⅱ 29.6%and group Ⅲ 9.2%). It also showed that the inhibitory effect became ber in higher concentration but still weaker than that in CsA group (80.7%). Conclusion Nidus vespae could inhibit the blastisation of lymphocyte in mixed culture system of lymphocyte and pancreatic islet, and the effect increased as the the concentration increased, which may suggest that nidus vespae could suppress the rejection induced by T cells.