Angiogenic activity of alginate-graft-PEI/pVEGF complexes in vivo / 生物工程学报

To study the angiogenic activity of amphoteric brush-type copolymer complex of alginate-graft-PEI/pVEGF (Alg-g-PEI/pVEGF) in vivo, we evaluated the toxicity of Alg-g-PEI/pVEGF complexes to rMSCs and zebra fish first. Then, we used gel retardation assay to investigate the protection of complex to pDNA against DNase I, serum and heparin. For in vivo study, we evaluated the angiogenic activity of Alg-g-PEI/pVEGF complexes by using CAM and zebra fish as animal models, PEI 25K/pVEGF and saline as positive and negative controls. Our results show that Alg-g-PEI protected pVEGF from enzymolysis and displacement of heparin in some degree, and its complexes with pVEGF were less toxic to rMSCs and zebra fish. Alg-g-PEI/pVEGF complexes induced significant angiogenesis, which was dosage-dependent. In CAM, when the dosage of pVEGF was 2.4 microg/CAM, Alg-g-PEI group achieved the maximum of angiogenesis, and the area ratio of vessel to the total surface was 44.04%, which is higher than PEI 25K group (35.90%) and saline group (24.03%) (**P < 0.01). In zebra fish, the angiogenesis increased with the increase of N/P ratios of Alg-g-PEI/pVEGF complexes in our studied range; when N/P ratio was 110, the optimal angiogenesis was obtained with vessel length of 1.11 mm and area of 1.70 x 10(3) pixels, which is higher than saline group (0.69 mm and 0.94 x 10(3) pixels) (**P < 0.01) and PEI 25k group (0.82 mm and 1.11 x 10(3) pixels) (**P < 0.01). Our results demonstratethat Alg-g-PEI/pVEGF significantly induces angiogenesis in CAM and zebra fish, and has a great potential in therapeutic angiogenesis.

Effects of demineralized bone matrix coated with OB-Cadherin on the capability of mesenchymal cells for adhesion and osteogenic differentiation / 中华急诊医学杂志

Objective To evaluate the adhesion, proliferation and osteogenic differentiation of rabbits' mesenchymal stem cells (MSCs) cultured in demineralized bone matrix coated with OB-Cadherin. Method The second generation of MSC s were seeded onto the OB-Cadherin cover over allogenic frozen-dried demineralized bone matrix(FDBM) and the FDBM without OB-Cadhefin as control, and then both were cultured separably in vitro. The densities of seeded cells, the adhesion rate were measured, and their ALP activity was assayed in order to take it as an index of cell adhesion, proliferation and osteogenic differentiation. The growth and adhension of MSCs on the FDBM was observed and evaluated microscopically and electronic scanning microscopically. Data were ex-pressed as means and standard deviation (x±s), and were analyzed with SPSS 12.0. Independent-Sanples T-test and Paired t test was used, and P<0.05 indicated statistically significant. Results There was no significant dif-ference in cell proliferation between modified FDBM and unmodified FDBM cultured fot 7, 14, 21 d. ays. After culture for 20 hours, the adhesion rate in the control group was (35.56±1.75)%, the densities of seeded cells were less than 2.7×104. The adhesion rate of cells in the modified group was consistent at 80%, whereas the densities of seeded cells were as high as 5.0×105 compared with control group (P<0.01). After cultured for 20 hours, the efficiency of cell adhesion in the modified FDBM was higher than that in the unmodified FDBM. After cultured for 7 days, the cultured MSC on modified FDBM expressed higher AIP activity, and after cultured for 14 days, the ALP activity on modified FDBM was much higher than that on unmodified FDBM (p<0.01). After cultured for 14 days, osteocalcin immunohistochemical positive rate of modified group was (71±11)%, while that of the control group was(49±8)% with significant difference Conclusion OB-Cadherin enhances cell adhesion to FDBM and promotes MSC to differentiate to osteoblast, but no obvious effects d OB-Cadherin on cell proliferation were observed.