Objective To evaluate the characterization, biocompatibil ity in vitro and in vivo, and antimicrobial activity of an injectable vancomycin-loaded borate glass/chitosan composite (VBC) so as to lay the foundation for its further cl inical application. Methods The sol id phase of VBC was constituted by borate glass and vancomycin, liquid phase was a mixture of chitosan, citric acid, and glucose with the proportion of 1 ∶ 10 ∶ 20. Solid phase and liquid phase was mixed withthe ratio of 2 ∶ 1. Vancomycin-loaded calcium sulfate (VCS) was produced by the same method using calcium sulfate instead of borate glass and sal ine instead of chitosan, as control. High performance liquid chromatography was applied to detect the release rate of antibiotics from VBC and VCS, and minimum inhibitory concentration (MIC) was tested by using an antibiotic tube dilution method. The structure of the VBC and VCS specimens before and 2, 4, 8, 16, and 40 days after immersion in D-Hank’s was examined by scanning electron microscopy, and the phase composition of VBC was analysed by X-ray diffraction after soaked for 40 days. Thirty-three healthy adult New Zealand white rabbits (weighing, 2.25-3.10 kg; male or female) were used to establ ish the osteomyel itis models according to Norden method. After 4 weeks, the models of osteomyel itis were successfully established in 28 rabbits, and they were randomly divided into 4 groups (groups A, B, C, and D). In group A (n=8), simple debridement was performed; in groups B and C (n=8), defect was treated by injecting VCS or VBC after debridement; and in group D (n=4), no treatment was given. The effectiveness of treatment was assessed using radiological and histological techniques after 2 months. Results The releases of vancomycin from VBC lasted for 30 days; the release rate of vancomycin reached 75% at the first 8 days, then could reached more than 90%. The releases of vancomycin from VCS lasted only for 16 days. The MIC of VBC and VCS were both 2 μg/mL. The VCS had a smooth glass crystal surface before immersion, however, it was almost degradated after 4 days. The fairly smooth surface of the VBC pellet became more porous and rougher with time, X-ray diffraction analysis of VBC soaked for 40 days indicated that the borate glass had gradually converted to hydroxyapatite. After 2 months, the best result of treatment was observed in group C, osteomyelitis symptoms disappeared. The X-ray scores of groups A, B, C, and D were 3.50 ± 0.63, 2.29 ± 0.39, 2.00 ± 0.41, and 4.25 ± 0.64, respectively; Smeltzer scores were 6.00 ± 0.89, 4.00 ± 0.82, 3.57 ± 0.98, and 7.25 ± 0.50, respectively. The scores were significantly higher in group D than in groups A, B, and C (P lt; 0.05), and in group A than in groups B and C (P lt; 0.05). The scores were higher in group B than in group C, but no significant difference was found (P gt; 0.05). Conclusion The VBC is effective in treating chronic osteomyelitis of rabbit by providing a sustained release of vancomycin, in addition to stimulating bone regeneration, so it may be a promising biomaterial for treating chronic osteomyelitis.
OBJECTIVE: To conduct the in vitro test on drug release of rifampin encapsulated in a carrier made of porous phosphate glass ceramics and to analyze main factors which affect the drug release rate. METHODS: A certain quantitative of rifampin was sealed in a hollow cylindrical capsule which consisted of chopped calcium phosphate crystal fiber obtained from glass crystallization. The rifampin concentration was measured in the simulated physiological solution in which the capsule soaked. RESULTS: Rifampin could be released in a constant rate from the porous glass ceramic carrier in a long time. The release rate was dependent on the size of crystal fiber and the wall thickness of the capsule. CONCLUSION: This kind of calcium phosphate glass ceramics can be a candidate of the carrier materials used as long term drug therapy after osteotomy surgery.
For a long period of time, silk fibroin has been applied in biomedical areas. Along with the development of biotechnology, new functions of silk fibroin are being found and developed. From the suture of surgery to the therapeutic drug and the ordinary tissue engineering frame to high grade frame with drug buffer system, exploitation of silk fibroin is constantly introduced with something new from the old ones. In our review, we summarize the applications of silk fibroin in tissue engineering, drug buffer system and medical care.
Objective To investigate the physicochemicalproperties of the calcium phosphate cement (CPC) containing Danshen composite injection and its drug release rate. Methods This experiment included 4 groups and each group contained 6 specimens. CPC (2 g) was mixed with the setting solution that served as thecontrol group; 0.1,0.5 and 1.0 ml of Danshen composites injection (concentration, 1 000 mg/ml; pH, 7.35) were respectively added to CPC (2 g), which were used as the experimental groups 1, 2 and 3. The resulting specimens were investigated by the X-ray diffraction (XRD), the fourier transformed infrared spectroscopy(FTIR), and the scanning electron microscope (SEM).ResultsThe XRD analysis showed that the control group had a typical diffraction pattern of the hydroxypatite (HAP), which was consistent with the standard patternof HAP. When more Danshen was added in the experimental groups, the diffractionpeaks of HAP gradually decreased; when the diffraction angle 2θ was about 25.92°, the HAP peaks disappeared. Based on the FTIR analysis, with an increase of the drug concentration, the absorption peak of the hydroxy groups decreased. The SEM showed that the size of the CPC particle was related to the drug concentration; with an increase of the drug concentration, the CPC particle increased in number, resulting in an increasing trend of coacervation. The elution test showed that the drugrelease rate and capacity varied with the different concentrationsof Danshen. The initial release rate was relatively great, but after 96 hours the rate slowed down, lasting for a long time. Conclusion The physicochemical properties of CPC do not change when a proper dose (0.1 ml/2 g) of Danshen isadded to CPC. The Danshen composite can be effectively released from CPC, and so CPCcan be used as an ideal drugdelivery carrier for Danshen composite.
Objective To assess the efficacy and safety of Chinese medicinal herbs for asymptomatic hepatitis B virus(HBV) infection. Data Source The trials registers of the Cochrane Hepato-Biliary Group, the Cochrane Library and the Cochrane Complementary Medicine Field were searched in combination with MEDLINE, EMBASE, and handsearches of Chinese journals and conference proceedings. Data Selection Randomized clinical trials with 3 months follow-up comparing Chinese medicinal herbs versus placebo, no intervention, non-specific treatment, or interferon treatment for asymptomatic HBV carriers were included. No language and blinding limitations were applied. Data Extraction Data were extracted independently by two reviewers. The methodological quality of trials was assessed by the Jadad-scale plus allocation concealment. Results Three randomized clinical trials (307 patients) with low methodological quality following patients for three months or more after the end of treatment were included. Herbal compound Jianpi Wenshen recipe showed significant effects on clearance of HBV markers compared to interferon: relative risk 2.40 (95 % CI 1.01 to 5.72) for clearance of serum HBsAg, and 2.54 (1.13 to 5.70) for seroconversion of HBeAg to anti-HBe. Phyllanthus amarus and Astragalus membranaceus showed no significant antiviral effect compared with placebo. Analysis of pooling eight randomized clinical trials with less than three months follow-up did not show a significant benefit of Chinese medicinal herbs on viral markers. No serious adverse event was observed. Conclusions There is insufficient evidence for treatment of asymptomatic HBVcarriers using Chinese medicinal herbs due to the low quality of the trials. Further randomized, double blind, placebo-controlled trials are needed.
It is difficult to repair long defect of bone. Biological bone carrier (BBC) was one of the artifical bone substitutes. It was obtained from human or swine bone after a series of biochemical treatment. It had good histocompatibility. It had the same components and structure of bone, and its biological strength was samiliar to bone. In clinic, BBC was applied to repair of long defect of bone in two cases. The lengths of defect were 13 cm and 11 cm, respectively. After followed up for 2 to 3 years, it was found that the implanted BBC had been combined with the femur with new bone. It had the same metabolism and density as that of the normal bone.
Bone morphogenetic protein (BMPs) has been so far regarded as one of the highly potent osteoinductive growth factors. Recombinant human bone morphogenetic proteins have been utilized extensively in the disciplines of orthopedics, stomatology, etc. For clinical application, BMPs are usually loaded in carriers with a controlled-release system, to maintain concentration to induce de novo bone formation at the desired site. In this article, the research advancements of the carriers and release systems of BMP are reviewed.
Objective To investigate the ability of gene-loaded lipopolysaccharide-amine nanopolymersomes (LNPs) in inducing osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) by in vitro gene transfection, where LNPs were used as a non-viral cationic carrier, and their properties were optimized during synthesis. Methods LNPs were synthesized by a graft-copolymerization method, and the effects of different pH environments during synthesis on physicochemical properties of LNPs and LNPs/plasmid of bone morphogenetic protein 2-green fluorescent protein (pBMP-2-GFP) complexes were explored. Then, optimized LNPs with maximum transfection efficiency and safe cytotoxicity in rat BMSCs were identified by cytotoxicity and transfection experiments in vitro. Thereafter, the optimized LNPs were used to mediate pBMP-2-GFP to transfect rat BMSCs, and the influences of LNPs/pBMP-2-GFP on osteogenic differentiation of BMSCs were evaluated by monitoring the cell morphology, concentration of BMP-2 protein, activity of alkaline phosphatase (ALP), and the formation of calcium nodules. Results The nitrogen content, particle size, and zeta potential of LNPs synthesized at pH 8.5 were lower than those of the other pH groups, with the lowest cytotoxicity (96.5%±1.4%) and the highest transfection efficiency (98.8%±0.1%). After transfection treatment, within the first 4 days, BMSCs treated by LNPs/pBMP-2-GFP expressed BMP-2 protein significantly higher than that treated by Lipofectamine2000 (Lipo)/pBMP-2-GFP, polyethylenimine 25K/pBMP-2-GFP, and the blank (non-treated). At 14 days after transfection, ALP activity in BMSCs treated by LNPs/pBMP-2-GFP was higher than that treated by Lipo/pBMP-2-GFP and the blank, comparable to that induced by osteogenic medium; with alizarin red staining, visible calcium nodules were found in BMSCs treated by LNPs/pBMP-2-GFP or osteogenic medium, but absent in BMSCs treated by Lipo/pBMP-2-GFP or the blank with apoptosis. At 21 days after transfection, transparent massive nodules were discovered in BMSCs treated by LNPs/pBMP-2-GFP, and BMSCs exhibited the morphologic features of osteoblasts. Conclusion LNPs synthesized at pH 8.5 has optimal transfection efficiency and cytotoxicity, they can efficiently mediate pBMP-2-GFP to transfect BMSCs, and successfully induce their directional osteogenic differentiation, whose inducing effect is comparable to the osteogenic medium. The results suggest that gene transfection mediated by LNPs may be a convenient and effective strategy in inducing directional differentiation of stem cells.
Objective Bioactive borate glass (BG) has good biocompatibil ity and biodegradation. To investigate the feasibilty of bioactive borate glass as a carrier of the antibiotic controlled-releasing by implanting vancomycin-loaded BG (VBG)into the focus of tibia chronic osteomyel itis after debridement. Methods VBG and vancomycin-loaded calcium sulfate (VCS) were prepared with a vancomycin content of 80 mg/g. Sixty-five New Zealand white rabbits, weighing 2.12-3.91 kg (mean, 2.65 kg), were used. The tibia chronic osteomyel itis rabbit models were establ ished by injecting methicill in-resistant Staphylococcus aureus (MRSA, 0.1 mL, 1 × 109 cfu/mL) into the right tibia of 65 rabbits. After 3 weeks of injection, 54 rabbits of successful models were randomly divided into groups A (n=11), B (n=11), C (n=16), and D (n=16). Simple debridement was performed in group A; BG, VCS, and VBG were implanted into the infection sites of groups B, C, and D respectively after thorough debridement. A sample of the debrided tissues was harvested for bacterial examination. The vancomycin serum levels were determined in groups C and D at 1, 2, 4, 10, 24, and 48 hours after operation. The boron serum levels were determined in groups B and D at 10, 24, 48, 72, and 120 hours after operation. After 8 weeks, the effectiveness was assessed radiographically, bacteriologically, and histopathol ogically. Results Ten rabbits died after operation. No vancomycin was detected in group C; the vancomycin level increased gradually, reached the highest level at 4 hours after operation, and then decreased rapidly in group D. No boron was detected in group B; the boron reached the highest serum level at 10 hours after operation, and then decreased gradually in group D. At 8 weeks, calcium sulfate degraded in group C; BG degraded partially in group D; and no obvious degradation was observedin group B. The repair effect was better in group D than in group C. There was no significant difference in radiograph scoring between groups A, B, C and D (P gt; 0.05) before operation, but there was significant difference between group D and groups A, B, C (P lt; 0.05) at 8 weeks after operation. The bacterial culture showed that all the MRSA results were positive in 4 groups. At 8 weeks, the negative rates of MRSA examination were 36.36%, 18.18%, 73.33%, and 81.25% respectively in groups A, B, C, and D, showing significant differences between group D and groups A, B (P lt; 0.05). The histopathological observation showed that a large number of new bones formed and no foreign body reaction occurred in group D. The histopathologic scores of groups A, B, C, and D were 6.45 ± 3.62, 7.55 ± 3.36, 4.27 ± 2.91, and 3.81 ± 3.04 respectively, showing significant differences between group D and groups A, B, and between group C and group B (P lt; 0.05). Conclusion VBG can improve the repair of bone defect in the treatment of chronic osteomyel itis.
Objective To prepare chitosan microcarriers and to use it to cultivate rat primary hepatocytes. Methods The crosslinked chitosan microcarrier was prepared by the reaction of glutaraldehyde with chitosan. Various factors that influence the preparation were studied and the reaction conditions were optimized. Rat primary hepatocytes cultured on chitosan microcarrier were observed by using phase contrast microscope and scanning electron microscope. Results Chitosan microcarriers with good properties could be prepared by adjusting the concentration of chitosan solution and the quantity of glutaraldehyde. Rat hepatocytes cultured on chitosan microcarriers retained the spherical shape as they have in vivo. And albumin secretion can last over one week. The highest albumin secretion rate reached 26.7μg/24h/ml. Conclusion Chitosan microcarriers is a promising scaffold for hepatocyte attachment, which can be used in bioartificial liver support system.