Tissue engineering for the repair of peripheral nerve injury

Peripheral nerve injury is a common clinical problem and affects the quality of life of patients. Traditional restoration methods are not satisfactory. Researchers increasingly focus on the field of tissue engineering. The three key points in establishing a tissue engineering material are the biological scaffold material, the seed cells and various growth factors. Understanding the type of nerve injury, the construction of scaffold and the process of repair are necessary to solve peripheral nerve injury and promote its regeneration. This review describes the categories of peripheral nerve injury, fundamental research of peripheral nervous tissue engineering and clinical research on peripheral nerve scaffold material, and paves a way for related research and the use of conduits in clinical practice.

Preparation and Biocompatibility of Porous Poly(vinylalcohol)-Glycosaminoglycan-Collagen Scaffold

This paper aims to prepare a PVA-GAG-COL composite with polyvinyl alcohol (PVA), glycosaminoglycan (GAG) and collagen (COL) by the method of freeze drying and to investigate the feasibility as a tissue engineering scaffold for tissue or organ repairing. In this study, SEM was used to observe the morphology. Biocompatibility was tested by cell culture with the extracted fluid of composite materials. Different proportional scaffolds could be obtained with different concentrations and alcoholysis degree of PVA. Different proportional scaffolds also had different porous structures. SEM proved that large amount of porous structure could be formed. Biocompatibility test showed that the extracted fluid of composite materials was nontoxic, which could promote the adhesion and proliferation of the fibroblast. Fibroblast could grow on the scaffold normally.A porous scaffold for tissue engineering with high water content can be fabricated by PVA, GAG and COL, which has excellent cell biocompatibility. The porous structure shows potential in tissue engineering and cell culture.

防电磁辐射纺织品测试方法与仪器研究

对防电磁辐射纺织品的测试方法及测试仪器进行了研究。详述了网络分析仪、纱线架、织物架、法兰同轴支架的选择与设计,通过对法兰同轴防电磁辐射测试仪进行合理的改进,实现了防电磁辐射纺织品屏蔽效能测试的简单快捷反应机制,并为防电磁辐射纺织品的设计与开发提供了基础与技术支撑,最后根据存在的不足对防电磁辐射纺织品测试仪的进一步研发提出了展望。

Digital design of scaffold for mandibular defect repair based on tissue engineering

Mandibular defect occurs more frequently in recent years,and clinical repair operations via bone transplantation are difficult to be further improved due to some intrinsic flaws.Tissue engineering,which is a hot research field of biomedical engineering,provides a new direction for mandibular defect repair.As the basis and key part of tissue engineering,scaffolds have been widely and deeply studied in regards to the basic theory,as well as the principle of biomaterial,structure,design,and fabrication method.However,little research is targeted at tissue regeneration for clinic repair operations.Since mandibular bone has a special structure,rather than uniform and regular structure in existing studies,a methodology based on tissue engineering is proposed for mandibular defect repair in this paper.Key steps regarding scaffold digital design,such as external shape design and internal microstructure design directly based on triangular meshes are discussed in detail.By analyzing the theoretical model and the measured data from the test parts fabricated by rapid prototyping,the feasibility and effectiveness of the proposed methodology are properly verified.More works about mechanical and biological improvements need to be done to promote its clinical application in future.

Application of collagen-chitosan/fibrin glue asymmetric scaffolds in skin tissue engineering

To create a scaffold that is suitable for the construction of tissue-engineered skin, a novel asymmetric porous scaffold with different pore sizes on either side was prepared by combining a collagen-chitosan porous membrane with fibrin glue. Tissue-engineered skin was fabricated using this asymmetric scaffold, fibroblasts, and a human keratinocyte line (HaCaT). Epidermal cells could be seen growing easily and achieved confluence on the fibrin glue on the upper surface of the scaffold. Scanning electron microscopy showed typical shuttle-like fibroblasts adhering to the wall of the scaffold and fluorescence microscopy showed them growing in the dermal layer of the scaffold. The constructed composite skin substitute had a histological structure similar to that of normal skin tissue after three weeks of culture. The results of our study suggest that the asymmetric scaffold is a promising biologically functional material for skin tissue engineering, with prospects for clinical applications.

Elevated high sensitive C-reactive protein and apelin levels after percutaneous coronary intervention and drug-eluting stent implantation

Objective:Percutaneous coronary intervention(PCI) triggers an acute inflammatory response,while sirolimus is known to have anti-inflammatory properties;the inflammatory system response to PCI after sirolimus-eluting stent placement remains unclear.The purpose of this study is to determine the changes in high sensitive C-reactive protein(hs-CRP) and apelin after PCI procedure and drug-eluting stent implantation in patients with and without reduced left ventricular systolic function.Methods:Forty-eight consecutive patients undergoing PCI at the Beijing Anzhen Hospital between July and September 2006 were recruited.Sirolimus-eluting stents were employed in all patients.Blood samples were drawn immediately before and 24 h after the procedure.Plasma hs-CRP and apelin levels were determined by enzyme immunoassay.Results:Paired t-test revealed a significant increase in both hs-CRP and apelin post-procedure(P=0.006 and P<0.0001,respectively).Patients with reduced left ventricular ejection fraction(LVEF) had significantly lower baseline apelin levels compared to those with normal ventricular function [(46.8±10.8) vs.(72.0±8.4) pg/ml,P<0.001].However,apelin increased to a level similar to the level of those with normal left ventricular systolic function 24 h after the PCI procedure [(86.7±11.6) vs.(85.1±6.1) pg/ml,P=0.72].Conclusions:hs-CRP and apelin levels increased after PCI and sirolimus-eluting stent implantation.Patients with impaired left ventricular systolic function had significantly lower baseline apelin levels,which increased significantly after PCI.

Hierarchically porous composite fabrics with ultrahigh metal–organic framework loading for zero-energy-consumption heat dissipation

The long-term safe operation of high-power equipment and integrated electronic devices requires efficient thermal management,which in turn increases the energy consumption further.Hence,the sustainable development of our society needs advanced thermal management with low,even zero,energy consumption.Harvesting water from the atmosphere,followed by moisture desorption to dissipate heat,is an efficient and feasible approach for zero-energy-consumption thermal management.However,current methods are limited by the low absorbance of water,low water vapor transmission rate(WVTR)and low stability,thus resulting in low thermal management capability.In this study,we report an innovative electrospinning method to process hierarchically porous metal–organic framework(MOF)composite fabrics with high-efficiency and zero-energy-consumption thermal management.The composite fabrics are highly loaded with MOF(75 wt%)and their WVTR value can be up to 3138 g m^(-2) d^(-1).The composite fabrics also exhibit stable microstructure and performance.Under a conventional environment(30℃,60%relative humidity),the composite fabrics adsorb water vapor for regeneration within 1.5 h to a saturated value Wsat of 0.614 g g^(-1),and a corresponding equivalent enthalpy of 1705.6 J g^(-1).In the thermal management tests,the composite fabrics show a strong cooling capability and significantly improve the performance of thermoelectric devices,portable storage devices and wireless chargers.These results suggest that hierarchically porous MOF composite fabrics are highly promising for thermal management of intermittent-operation electronic devices.

Novel three-dimensional nerve tissue engineering scaffolds and its biocompatibility with Schwann cells

Objective： To develop a novel scaffolding method for the copolymers poly lactide-co-glycolide acid （PLGA） to construct a three-dimensional （3-D） scaffold and explore its biocompatibility through culturing Schwann cells （SCs） on it. Methods： The 3-D scaffolds were made by means of melt spinning, extension and weaving. The queueing discipline of the micro-channels were observed under a scanning electronic microscope （SEM）.The sizes of the micropores and the factors of porosity were also measured. Sciatic nerves were harvested from 3-day-old Sprague Dawley （SD） rats for culture of SCs. SCs were separated, purified, and then implanted on PLGA scaffolds, gelatin sponge and poly-L-lysine （PLL）-coated tissue culture poly-styrene （TCPS） were used as biomaterial and cell-supportive controls, respectively. The effect of PLGA on the adherence, proliferation and apoptosis of SCs were examined in vitro in comparison with gelatin sponge and TCPS. Results： The micro-channels arrayed in parallel manners, and the pore sizes of the channels were uniform. No significant difference was found in the activity of Schwann cells cultured on PLGA and those on TCPS （P〉0.05）, and the DNA of PLGA scaffolds was not damaged. Conclusion： The 3-D scaffolds developed in this study have excellent structure and biocompatibility, which may be taken as a novel scaffold candidate for nerve-tissue engineering.

Promotion of microvasculature formation in alginate composite hydrogels by an immobilized peptide GYIGSRG

The ability to create artificial thick tissues is a major tissue engineering problem, requiring the formation of a suitable vascular supply. In this work we examined the ability of inducing angiogenesis in a bioactive hydrogel. GYIGSRG （NH2-Gly-Tyr-Ile- Gly-Ser-Arg-Gly-COOH, GG） has been conjugated to sodium alginate （ALG） to synthesize a biological active biomaterial ALG-GG. The product was characterized by IH NMR, FT-IR and elemental analysis. A series of CaCO3/ALG-GG composite hydrogels were prepared by crosslinking ALG-GG with D-glucono-8-1actone/calcium carbonate （GDL/CaCO3） in different molar ratios. The mechanical strength and swelling ratio of the composite hydrogels were studied. The results revealed that both of them can be regulated under different preparation conditions. Then, CaCO3/ALG-GG composite hydrogel was im- planted in vivo to study the ability to induce angiogenesis. The results demonstrated that ALG-GG composited hydrogel can induce angiogenesis significantly compared with non-modified ALG group, and it may be valuable in the development of thick tissue engineering scaffold.

Fabrication and Properties of Poly(vinylalcohol)-glycosaminoglycantype I Collagen Composite Membrane as Tissue Regeneration Scaffolds

The objective of this paper is to design a based on composite membrane with certain mechanical porous polyvinyl alcohol （PVA） strength and biocompatibilities serving as tissue regenerative scaffolds. PVA-glycosaminoglycan （GAG）-type I collagen （COL） composite membrane was fabricated by PVA with different molecular weight （Mw） and alcoholysis degree （AD） being blended with certain amounts of GAG and COL and dried at 38~C for 24 h. The water content of the composite membranes were from 61.9% to 95.1% and swelling ratio ranged from 123.6% to 621.7%. Scanning electron micro- scope （SEM） analysis proved that PVA-GAG-COL composite membrane has porous and homogenous structure. Biocompatibility test results showed that the composite membrane was nontoxic, which could promote adhesion and proliferation of fibroblasts on the com- posite membrane. In conclusion, PVA-GAG-COL composite membrane with high water content and swelling ratio, suitable mechanical strength and good biocompatibility, has potential in tissue engineering and regenerative medicine.