Objective To review the research progress of promoting the bone formation at early stage by components of the extracellular matrix (ECM). Methods Recent literature concerning the influence of these components on new bone formation and bone/implant contact was extensively reviewed and summarized. Results Coating of titanium or hydroxyapatite implants with organic components of the ECM (such as collagen type I, chondroitin sulfate, and Arg-Gly-Asp peptide) offers great potential to improve new bone formation and enhance bone/implant contact, which in turn will shorten recovery time and improve implant stability. Conclusion The increasing knowledge about the role of the ECM for recruitment, proliferation, differentiation of cells, and regeneration of tissue will eventually deal to the creating of an artificial ECM on the implant that could allow a defined adjustment of the required properties to support the healing process.
Objective To transplant intravenously human brain-derived neurotrophic factor (hBDNF) genemodified bone marrow mesenchymal stem cells (BMSCs) marked with enhanced green fluorescent protein (EGFP) to injured spinal cord of adult rats, then to observe the viabil ity of the cells and the expressions of the gene in spinal cord, as well as theinfluence of neurological morphological repairing and functional reconstruction. Methods Ninety-six male SD rats weighing (250 ± 20) g were randomly divided into 4 groups: hBDNF-EGFP-BMSCs transplantation group (group A, n=24), Ad5-EGFPBMSCs transplantation group (group B, n=24), control group (group C, n=24), and sham operation group (group D, n=24). In groups A, B, and C, the spinal cord injury models were prepared according to the modified Allen method at the level of T10 segment, and after 3 days, 1 mL hBDNF-EGFP-BMSCs suspension, 1 mL Ad5-EGFP-BMSCs suspension and 1 mL 0.1 mol/L phosphate buffered sal ine (PBS) were injected into tail vein, respectively; in group D, the spinal cord was exposed without injury and injection. At 24 hours after injury and 1, 3, 5 weeks after intravenous transplantation, the structure and neurological function of rats were evaluated by the Basso-Beattie-Bresnahan (BBB) score, cortical somatosensory evoked potential (CSEP) and transmission electron microscope. The viabil ity and distribution of BMSCs in the spinal cord were observed by fluorescent inverted phase contrast microscope and the level of hBDNF protein expression in the spinal cord was observed and analyzed with Western blot. Meanwhile, the expressions of neurofilament 200 (NF-200) and synaptophysin I was analyzed with immunohi stochemistry. Results After intravenous transplantation, the neurological function was significantly improved in group A. The BBB scores and CSEP in group A were significantly higher than those in groups B and C (P lt; 0.05) at 3 and 5 weeks. The green fluorescence expressions were observed at the site of injured spinal cord in groups A and B at 1, 3, and 5 weeks. The hBDNF proteinexpression was detected after 1, 3, and 5 weeks of intravenous transplantation in group A, while it could not be detected in groups B, C, and D by Western blot. The expressions of NF-200 and synaptophysin I were ber and ber with transplanting time in groups A, B, and C. The expressions of NF-200 and synaptophysin I were best at 5 weeks, and the expressions in group A were ber than those in groups B and C (P lt; 0.05). And the expressions of NF-200 in groups A, B, and C were significantly ber than those in group D (P lt; 0.05), whereas the expressions of synaptophysin I in groups A, B, and C were significantly weaker than those in group D (P lt; 0.05). Ultramicrostructure of spinal cords in group A was almost normal. Conclusion Transplanted hBDNF-EGFP-BMSCs can survive and assemble at the injured area of spinal cord, and express hBDNF. Intravenous implantation of hBDNF-EGFP-BMSCs could promote the restoration of injured spinal cord and improve neurological functions.
Objective To review the current researches of scaffold materials for skeletal muscle tissue engineering, to predict the development trend of scaffold materials in skeletal muscle tissue engineering in future. Methods The related l iterature on skeletal muscle tissue engineering, involving categories and properties of scaffold materials, preparative techniqueand biocompatibil ity, was summarized and analyzed. Results Various scaffold materials were used in skeletal muscle tissue engineering, including inorganic biomaterials, biodegradable polymers, natural biomaterial, and biomedical composites. According to different needs of the research, various scaffolds were prepared due to different biomaterials, preparative techniques, and surface modifications. Conclusion The development trend and perspective of skeletal muscle tissue engineering are the use of composite materials, and the preparation of composite scaffolds and surface modification according to the specific functions of scaffolds.
【Abstract】 Objective To evaluate the biocompatibil ity of the sheep BMSCs cultured on the surface of photografting modified copolymers of 3-hydroxybutyrate and 3-hydroxyvalerate(PHBV). Methods BMSCs were isolated from bone marrow of the posterior il iac crest of a 6-month old sheep by whole marrow adherent culture method. The 3rd passage BMSCs were seeded onto modified PHBV and conventional PHBV films, or three-dimension scaffolds. Cell-adhesion rates were calculated by hemocytometer at 1, 2 and 6 hours after seeded. Cell morphology was examined by scanning electron microscope when the BMSCs were cultured for 3 days, 1 week and 3 weeks. Cell cycle was analyzed by flow cytometry at 5 days after seeded. The content of protein in BMSCs was determined by BCA assay and the content of DNA was quantified by Hoechst 33258 assay at 4, 8 and 12 days after seeded. Results At 1 hour after seeded, cell-adhesion rate on modified PHBV films (52.7% ± 6.0%) was significantlyhigher than that of conventional PHBV films (37.5% ± 5.3%) (P lt; 0.05); At 2 and 6 hours after seeded, cell-adhesion rate of modified PHBV films was similar to that of PHBV films (P gt; 0.05). The surface of modified PHBV film was rougher. In the early culture stage, more cells adhered to modified PHBV and the cells displayed much greater spreading morphology. Furthermore, ECM on modified PHBV were richer. There were no significant differences between the trial team and the control on the cell cycle and the content of DNA and protein of BMSCs (P gt; 0.05). Conclusion Photografting modification on PHBV can promote BMSCs’ adhesion and enhance their biocompatibil ity.
Objective To summarize the current progress in the genetic modification of vascular prostheses and to look forward to the future of genetic modification in vascular prostheses. Methods PubMed onl ine search with the key words of “vascular prostheses, gene” was undertaken to identify articles about the genetic modification of vascular prostheses. Then these articles were reviewed and summarized. Results To improve long-term patency of vascular prostheses, various genes were transfected into seeded cells. The antithrombosis activity of local vessels increased. Conclusion Progresses in tissue engineering and molecular biology make possible endothel ial ization and genetic modification of vascular prostheses. However, because most relevant researches are still basic experiments, further study is needed before cl inical appl ication.
Objective To investigate the memory amelioration of the Alzheimer disease (AD)model rat after being transplanted the single neural stem cells(NSC) and NSC modified with human brain-derived neurotrophic factor（hBDNF） gene. Methods Forty SD rats were divided evenly into 4 groups randomly. The AD model rats were made by cutting unilaterallythe fibria fornix of male rats. Ten to twelve days after surgery, the genetically modified and unmodified NSC were implanted into the lateral cerebral ventricle of group Ⅲ and group Ⅳ respectively. Two weeks after transplantation, theamelioration of memory impairment of the rats was detected by Morris water maze. Results The average escaping latency of the group Ⅲ and group Ⅳ (41.84±21.76 s,25.23±17.06 s respectively) was shorter than that of the group Ⅱ(70.91±23.67 s) (Plt;0.01). The percentage of swimming distance inthe platform quadrant in group Ⅲ (36.9%) and in group Ⅳ(42.0%) was higherthan that in the group Ⅱ(26.0%) (Plt;0.01). More marginal and random strategies were used in group Ⅱ.The percentage of swimming distance in the platform quadrant in group Ⅳ was also greater than that in group Ⅲ(Plt;0.05). There were no significant differences in the average escaping latency, the percentage of swimming distance in the platform quadrant and the probe strategy between group Ⅳ and group Ⅰ(Pgt;0.05).More lineal and oriented strategies were used in group Ⅳ. Conclusion The behavioral amelioration of AD model rat was obtained by transplanting single NSC and hBDNF-gene-modified NSC. The effect of the NSC group modified with hBDNF gene is better than that of the groupⅢ.
OBJECTIVE: To modify the surface of poly(D,L-lactide) film by anhydrous ammonia gaseous plasma treatment. METHODS: The changes of contact angles were measured and surface energy were calculated. Mouse 3T3 fibroblast cells were cultured on plasma modified and control poly(D,L-lactide) films. RESULTS: It was found that the hydrophilicity and surface energy of the materials have been increased after plasma treatment. Cell culture results showed that ammonia plasma treatment could promote the cell attachment and cells growth. After 4 days culture, the cells on the plasma treated films were 2-folds quantitatively compared with that of the control films. CONCLUSION: Ammonia plasma treatment can improve the cell affinity to poly(D,L-lactide).
Objective To observe the expressions of DNA methyltransferases (DNMTs) 1, 3a and 3b in retinoblastoma (RB). Methods Sixty-two RB samples and six normal retinas were studied, including 17 poorly differentiated and 45 well differentiated samples; 16 invasive and 46 non-invasive samples. The expressions of DNMT1, 3a, and 3b, and Ki-67 were detected using immunohistochemical analysis. Brown staining of nuclei was considered to represent the positive stain for DNMT1, 3a and 3b, and ki-67, blue staining as negative. The level of high expression of nuclear staining was, positive cells in DNMT1ge;65%, in DNMT3age;60% and in DNMT3bge;40%. The correlations of DNMT1, 3a and 3b expression in RB samples, and MIB-1 labeling index were analyzed. Results Viewed under the light microscope, negative expressions of DNMT1, 3a and 3b were demonstrated in normal retinas, however, positive expression was observed in RB samples, with 100% in DNMT1, 98% in DNMT3a and 92% in DNMT3b. Comparing well differentiated RB samples with poorly differentiated samples, significant differences were found in high expression of DNMT1 (chi;2=12.57,P＜0.05) and DNMT3a (chi;2=10.54,P＜0.05); also in the positive cells of DNMT1 (U=179,P＜0.05) and DNMT3a (U=198,P＜0.05). No significant difference was found comparing high expression (chi;2=1.5,P＞0.05) and positive cells (U=307,P＞0.05) of DNMT3b. When comparing invasive tumor tissues with non-invasive tumors, significant differences were shown between high expression (chi;2=4.72,P＜0.05) and positive cells comparing DNMT1 (U=236,P＜0.05). No significant difference was shown in high expression (chi;2=3.53,0.84; P＞0.05) in DNMT3a and DNMT3b, or in comparison with positive cells (U=338,257;P＞0.05). The expression of DNMTs was positively correlated with the MIB-1 labeling index in RB tissues (R2=0.554,0.376,0.219;P＜0.05). Conclusion There are high expressions of DNMT1,3a,and 3b in RB.
Objective To review the relationship between histone modifications and gastrointestinal cancer. Methods Literatures on histone modifications and the relationship between histone modifications and gastrointestinal cancer were collected and reviewed. Results Histone modifications played an important role in the establishment of gene silencing during tumorgenesis. DNA methylation and histone modifications might interact with each other and form a complex network to establish and maintain gene silencing. Restoring gene function silenced by epigenetic changes in cancer had the potential of ‘normalizing’ cancer cells, which was named epigenetic therapy. Epigenetic therapy was very promising in prevention and treatment of gastrointestinal cancer, but many unsolved issues remain which need to be addressed in future studies. Conclusion Histone modifications are associated with the pathogenesis of gastrointestinal cancer. Restoring gene function silenced by epigenetic changes may have a great role in the prevention and treatment of gastrointestinal cancer.
The rutile structure titanium oxide (Ti-O) film was prepared on the pure titanium material TA2 (99.999%) surface by the magnetic filter high vacuum arc deposition sputtering source. The method can not only maintain the material mechanical properties, but also improve the surface properties for better biocompatibility to accommodate the physiological environment. The preparation process of the Ti-O film was as follows. Firstly, argon ions sputtered to the TA2 substrate surface to remove the excess impurities. Secondly, a metal ion source generated Ti ions and oxygen ions by the RF discharge. Meanwhile a certain negative bias was imposed on the sample. There a certain composition of Ti-O film was obtained under a certain pressure of oxygen in the vacuum chamber. Finally, X-ray diffraction was used to research the structure and composition of the film. The results showed that the Ti-O film of the rutile crystal structure was formed under the 0.18 Pa oxygen partial pressure. A Nano scratch experiment was used to test the coating adhesion property, which demonstrated that the film was stable and durable. The contact angle experiment and the platelet clotting experiment proved that the modified surface method had improved platelet adhesion performance, and, therefore, the material possessed better biocompatibility. On the whole, the evaluations proved the modified material had excellent performance.