Objective To investigate the biocompatibil ity of silk fibroin nanofibers scaffold with olfactory ensheathing cells (OECs) and to provide an ideal tissue engineered scaffold for the repair of spinal cord injury (SCI). Methods Silk fibroin nanofibers were prepared using electrospinning techniques and were observed by scanning electron microscope (SEM). Freshly isolated OECs from SD rats purified by the modified differential adherent velocity method were cultured. The cells at passage 1 (1 × 104 cells/cm2) were seeded on the poly-l-lysine (control group) and the silk fibroin nanofibers (experimental group) coated coversl ips in Petri dish. At desired time points, the morphological features, growth,and adhesion of the cells were observed using phase contrast inverted microscopy. The OECs were identified by the nerve growth factor receptor p75 (NGFR p75) immunofluorescence staining. The viabil ity of OECs was examined by l ive/dead assay. The prol iferation of OECs was examined by MTT assay. The cytotoxicity of the nanofibers was evaluated. Results The SEM micrographs showed that the nanofibers had a smooth surface with sol id voids among the fibers, interconnecting a porous network, constituted a fibriform three dimensional structure and the average diameter of the fibers was about (260 ± 84) nm. The morphology of OECs on the experimental group was similar to the cell morphology on the control group, the cells distributed along the fibers, and the directions of the cell protrusions were in the same as that of the fibers. Fluorescence microscopy showed that the purity of OECs was 74.21% ± 2.48% in the experimental group and 79.05% ± 2.52% in the control group 5 days after culture. There was no significant difference on cell purity between two groups (P gt; 0.05). The OECs in the experimental group stained positive for NGFR p75 compared to the control group, indicating that the cells in the experimental group still maintained the OECs characteristic phenotype. Live/dead staining showed that high viabil ity was observed in both groups 3 days after culture. There was no significant difference on cell viabil ity between two groups. The prol iferation activity at 1, 3, 5, 7, and 10 days was examined by MTT assay. The absorbency values of the control group and the experimental group had significant differences 3 and 5 days after culture (P lt; 0.05). The relative growth rates were 95.11%, 90.35%, 92.63%, 94.12%, and 94.81%. The cytotoxicity of the material was grade 1 and nonvenomous according to GB/T 16886 standard. Conclusion Silk fibroin nanofibers scaffold has good compatibility with OECs and is a promising tissue engineered scaffold for the repair of SCI.
The compressive strength of the original bone tissue was tested, based on the raw human thigh bone,bovine bone,pig bone and goat bone. The four different bone-like apatites were prepared by calcining the raw bones at 800℃ for 8 hours to remove organic components. The comparison of composition and structure of bone-like apatite from different bone sources was carried out with a composition and structure test. The results indicated that the compressive strength of goat bone was similar to that of human thigh bone, reached (135.00±7.84) MPa; Infrared spectrum (IR), X-ray diffraction (XRD) analysis results showed that the bone-like apatite from goat bone was much closer to the structure and phase composition of bone-like apatite of human bones. Inductively Coupled Plasma (ICP) test results showed that the content of trace elements of bone-like apatite from goat bone was closer to that of apatite of human bone. Energy Dispersive Spectrometer (EDS) results showed that the Ca/P value of bone-like apatite from goat bone was also close to that of human bone, ranged to 1.73±0.033. Scanning electron microscopy (SEM) patterns indicated that the macrographs of the apatite from human bone and that of goat bone were much similar to each other. Considering all the results above, it could be concluded that the goat bone-like apatite is much similar to that of human bone. It can be used as a potential natural bioceramic material in terms of material properties.
The study of viruses traditionally focused on their roles as infectious agents and as tools for understanding cell biology. Recently, however, with the development of structural biology, viruses have now been receiving particular attention in nanotechnology. By chemical methods or by gene modification, viruses have been functionalized as potential building blocks for several applications, such as drug/gene delivery vehicles, advanced vaccine vehicles, and special inorganic or organic nanomaterials. Here we highlight some of the recent progresses in the medical applications of viruses.
In order to enhance the anticoagulant properties of decellularized biological materials as scaffolds for tissue engineering research via heparinized process, the decellularized porcine liver scaffolds were respectively immobilized with heparin through layer-by-layer self-assembly technique (LBL), multi-point attachment (MPA) or end-point attachment (EPA). The effects of heparinization and anticoagulant ability were tested. The results showed that the three different scaffolds had different contents of heparin. All the three kinds of heparinized scaffolds gained better performance of anticoagulant than that of the control scaffold. The thrombin time (TT), prothrombin time (PT) and activated partial thromboplastin time (APTT) of EPA scaffold group were longest in all the groups, and all the three times exceeded the measurement limit of the instrument. In addition, EPA scaffolds group showed the shortest prepared time, the slowest speed for heparin release and the longest recalcification time among all the groups. The decellularized biological materials for tissue engineering acquire the best effect of anticoagulant ability in vitro via EPA heparinized technique.
The aim of this study was to establish an assessment method for determiningα-Gal(α-1, 3-galactosyle) epitopes contained in animal tissue or animal tissue-derived biological materials with ELISA inhibition assay. Firstly, a 96 well plate was coated with Galα-1, 3-Gal/bovine serum albumin (BSA) as a solid phase antigen and meanwhile, the anti-α-Gal M86 was used to react withα-Gal antigens which contained in the test materials. Then, the residual antibodies (M86) in the supernatant of M86-Gal reaction mixture were measured using ELISA inhibition assay by theα-Gal coating plate. The inhibition curve of the ELISA inhibition assay, the R2=0.999, was well established. Checking using bothα-Gal positive materials (rat liver tissues) andα-Gal negative materials (human placenta tissues) showed a good sensitivity and specificity. Based on the presently established method, theα-Gal expression profile of rat tissues, decellular animal tissue-derived biological materials and porcine dermal before and after decellular treatment were determined. The M86 ELISA inhibition assay method, which can quantitatively determine theα-Gal antigens contained in animal tissues or animal tissue-derived biomaterials, was refined. This M86 specific antibody based-ELISA inhibition assay established in the present study has good sensitivity and specificity, and could be a useful method for determining remnantα-1, 3Gal antigens in animal tissue-derived biomaterials.
Due to its special sequence structure, spider silk protein has unique physical and chemical properties, mechanical properties and excellent biological properties. With the expansion of the application value of spider silk in many fields as a functional material, progress has been made in the studies on the expression of recombinant spider silk proteins through many host systems by gene recombinant techniques. Recombinant spider silk proteins can be processed into high performance fibers, and a wide range of non-fibrous morphologies. Moreover, for their excellent biocompatibility and low immune response they are ideal for biomedical applications. Here we review the process and mechanism of preparation in vitro, chemistry and genetic engineering modification on recombinant spider silk protein.
Three-dimensional (3D) bio-printing is a novel engineering technique by which the cells and support materials can be manufactured to a complex 3D structure. Compared with other 3D printing methods, 3D bio-printing should pay more attention to the biocompatible environment of the printing methods and the materials. Aimed at studying the feature of the 3D bio-printing, this paper mainly focuses on the current research state of 3D bio-printing, with the techniques and materials of the bio-printing especially emphasized. To introduce current printing methods, the inkjet method, extrusion method, stereolithography skill and laser-assisted technique are described. The printing precision, process, requirements and influence of all the techniques on cell status are compared. For introduction of the printing materials, the cross-link, biocompatibility and applications of common bio-printing materials are reviewed and compared. Most of the 3D bio-printing studies are being remained at the experimental stage up to now, so the review of 3D bio-printing could improve this technique for practical use, and it could also contribute to the further development of 3D bio-printing.
ObjectiveTo evaluate the bone repair efficacy of the new nano-hydroxyapatite (n-HA)/polyurethane (PU) composite scaffold in the treatment of chronic osteomyelitis in tibia.MethodsA novel levofloxacin@mesoporous silica microspheres (Lev@MSNs)/n-HA/PU was successfully synthesized. Its surface structure was observed by scanning electron microscopy (SEM). Fifty adult female New Zealand rabbits were randomly selected, and osteomyelitis was induced in the right tibia of the rabbit by injecting bacterial suspension (Staphylococcus aureus; 3×107 CFU/mL), which of the method was described by Norden. A total of 45 animals with the evidence of osteomyelitis were randomly divided into 4 groups, and the right medullary cavity of each animal was exposed. Animals in the blank control group (group A, n=9) were treated with exhaustive debridement only. The remaining animals were first treated by exhaustive debridement, and received implantations of 5 mg Lev@PMMA (group B, n=12), 1 mg Lev@MSNs/n-HA/PU (group C, n=12), and 5 mg Lev@MSNs/n-HA/PU (group D, n=12), respectively. At 12 weeks postoperatively, the right tibia of rabbits were observed by X-ray film, and then gross observation, methylene blue/acid fuchsin staining, and SEM observation of implant-bone interface, as well as biomechanical test (measuring the maximal compression force) were performed.ResultsX-ray films showed that the infection were severer than those of preoperation in group A, while the control of inflammation and bone healing of rabbits in group D were obviously better than those at preoperation. The gross observation showed extensive bone destruction in group A, a significant gap between bone tissue and the material in groups B and C, and close combination between bone tissue and the material in group D. The histology of the resected specimens showed that there was no obvious new bone formation around the materials in groups B and C, and there was abundant new bone formation around the periphery and along the voids of the materials and active bone remodeling in group D. The SEM observation of the bone-implant interface demonstrated that no new bone formation was observed at the bone-implant interface in groups B and C. However, bony connections and blurred boundaries were observed between the material and host bone tissue in group D. The biomechanical test showed the maximal compression force of groups B and D were significantly higher than that of groups A and C (P<0.05), but there was no significant difference between groups B and D (P>0.05).ConclusionThe novel synthetic composite Lev@MSNs/n-HA/PU exhibit good antibacterial activities, osteoconductivity, and biomechanical properties, and show great potential in the treatment of chronic osteomyelitis of rabbits.
Artificial bone repair material is the best substitute for autologous bone transplantation. Bone repair materials are constantly being replaced and upgraded, which can be roughly divided into three generations: bioinert materials, bioactive materials, and smart materials. Research and development of bone repair materials with multiple biological activities, in vivo degradation property that perfectly fit for new bone formation, and ability of complete reconstruction of bone tissue in physiological state are the focus of future research.
Marine-derived biopolymers are excellent raw materials for biomedical products due to their abundant resources, good biocompatibility, low cost and other unique functions. Marine-derived biomaterials become a major branch of biomedical industry and possess promising development prospects since the industry is in line with the trend of " green industry and low-carbon economy”. Chitosan and alginates are the most commonly commercialized marine-derived biomaterials and have exhibited great potential in biomedical applications such as wound dressing, dental materials, antibacterial treatment, drug delivery and tissue engineering. This review focuses on the properties and applications of chitosan and alginates in biomedicine.