一种新型去细胞猪主动脉支架的构建和评价

目的:探索超声波联合曲拉通X-100制备猪升主动脉去细胞支架的方法及效果.方法:从体重相近的中华实验猪制备新鲜主动脉标本150份,随机分为5组:空白对照组、超声波(90 kW)联合曲拉通X-100组、超声波(135 kW)联合曲拉通X-100组、超声波(180 kW)联合曲拉通X-100组和曲拉通X-100组,通过组织学及电镜观察、生物力学性能测定、免疫组织化学法检测层黏连蛋白和纤维连接蛋白的蛋白表达变化等方法,分析比较各组去细胞的效果.结果:超声波联合曲拉通X-100组可完全去除动脉内膜细胞,组织形态、生物力学性能等保持良好,层黏连蛋白和纤维连接蛋白的保存明显优于传统的化学去细胞方法.结论:超声波联合曲拉通X-100组去细胞效果优于传统化学去污剂,是理想的制备猪动脉去细胞支架的方法.     

Electrospun silk biomaterial scaffolds for regenerative medicine

Electrospinning is a versatile technique that enables the development of nanofiber-based biomaterial scaffolds. Scaffolds can be generated that are useful for tissue engineering and regenerative medicine since they mimic the nanoscale properties of certain fibrous components of the native extracellular matrix in tissues. Silk is a natural protein with excellent biocompatibility, remarkable mechanical properties as well as tailorable degradability. Integrating these protein polymer advantages with electrospinning results in scaffolds with combined biochemical, topographical and mechanical cues with versatility for a range of biomaterial, cell and tissue studies and applications. This review covers research related to electrospinning of silk, including process parameters, post treatment of the spun fibers, functionalization of nanofibers, and the potential applications for these material systems in regenerative medicine. Research challenges and future trends are also discussed.     

Electrospun materials as potential platforms for bone tissue engineering

Nanofibrous materials produced by electrospinning processes have attracted considerable interest in tissue regeneration, including bone reconstruction. A range of novel materials and processing tools have been developed to mimic the native bone extracellular matrix for potential applications as tissue engineering scaffolds and ultimately to restore degenerated functions of the bone. Degradable polymers, bioactive inorganics and their nanocomposites/hybrids nanofibers with suitable mechanical properties and bone bioactivity for osteoblasts and progenitor/stem cells have been produced. The surface functionalization with apatite minerals and proteins/peptides as well as drug encapsulation within the nanofibers is a promising strategy for achieving therapeutic functions with nanofibrous materials. Recent attempts to endow a 3D scaffolding technique to the electrospinning regime have shown some promise for engineering 3D tissue constructs. With the improvement in knowledge and techniques of bone-targeted nanofibrous matrices, bone tissue engineering is expected to be realized in the near future.     

Micro- and nanotechnologies for intelligent and responsive biomaterial-based medical systems

Advances in medical treatments of a wide variety of pathophysiological conditions require the development of better therapeutic agents, as well as a combination of the required therapeutic agents with device-integrated biomaterials that can serve as sensors and carriers. Combination of micro- and nano-fabricated systems with intelligent biomaterials that have the ability to sense and respond is a promising avenue for the development of better diagnostic and therapeutic medical systems. Micro- and nano-electromechanical systems (MEMs and NEMs) are now becoming a family of potentially powerful new technologies for drug delivery, diagnostic tools, and tissue engineering. Improvements in micro- and nano-fabrication technologies have enhanced the ability to create better performing therapeutic systems for numerous pathophysiological applications. More importantly, MEMS- and NEMS-based tissue regeneration scaffolds, biosensors, and drug delivery devices provide new opportunities to mimic the natural intelligence and response of biological systems.     

Engineered bidirectional communication mediates a consensus in a microbial biofilm consortium

Microbial consortia form when multiple species colocalize and communally generate a function that none is capable of alone. Consortia abound in nature, and their cooperative metabolic activities influence everything from biodiversity in the global food chain to human weight gain. Here, we present an engineered consortium in which the microbial members communicate with each other and exhibit a "consensus" gene expression response. Two colocalized populations of Escherichia coli converse bidirectionally by exchanging acyl-homoserine lactone signals. The consortium generates the gene-expression response if and only if both populations are present at sufficient cell densities. Because neither population can respond without the other's signal, this consensus function can be considered a logical AND gate in which the inputs are cell populations. The microbial consensus consortium operates in diverse growth modes, including in a biofilm, where it sustains its response for several days.     

Biocompatibility of acellular human pericardium

BACKGROUND: Previous studies have shown successful decellularization of human pericardium without affecting the major structural components and strength of the matrix. The aim of this study was to assess the biocompatibility and reseeding potential of the acellular human pericardial scaffold. MATERIALS AND METHODS: Pericardia were treated sequentially with hypotonic buffer, sodium dodecyl sulfate, and a nuclease solution. The presence of cellular attachment factors after decellularization was evaluated using immunohistochemistry. The scaffold was seeded with dermal fibroblasts and cellular attachment to and numbers of cells penetrating were assessed over time. Biocompatibility was also evaluated following subcutaneous implantation into a mouse model for three months. RESULTS: After decellularization, the scaffold stained positively for fibronectin, but collagen IV and laminin staining was reduced. Seeded fibroblasts attached to the mesothelial surface and were visualized in the tissue within a week of seeding. The majority of fibroblasts in the tissue were viable and there was evidence of remodeling of the matrix. Analysis of the explanted tissues from mice showed that fresh/frozen and glutaraldehyde-fixed pericardia were encapsulated with a thick layer of inflammatory cells and fibrous tissue. In contrast, the decellularized scaffold was infiltrated with myofibroblasts, CD34+ cells and macrophages, indicating a healthy repair process. Compared with the glutaraldehyde-fixed tissue, the calcium content of the fresh/frozen and decellularized pericardia was negligible. CONCLUSIONS: The pericardial scaffold was biocompatible in vitro and in the mouse model in vivo.     

NMR assessment of Me(2)SO in decellularized cryopreserved aortic valve conduits

INTRODUCTION: Decellularized cryopreserved allograft vascular tissue may provide a nonimmunogenic scaffold that is suitable for repopulation by cells from a variety of sources, conferring the potential for growth and repair. Although dimethyl sulfoxide (Me(2)SO) is generally regarded as a safe cryoprotectant, even low levels may alter function of repopulating cells. We investigated the residual concentration of Me(2)SO in the aqueous compartment of cryopreserved ovine aortic valve conduits following decellularization. MATERIALS AND METHODS: Aortic valve conduits from Suffolk sheep were cryopreserved in 1.1 M (7.5% vol/vol) Me(2)SO according to the protocol of our local tissue bank. Three aortic valve conduits were decellularized in a series of hypotonic and hypertonic Tris buffers. Tissue samples were taken at regular time intervals throughout the decellularization process and equilibrated in double distilled, deionized H(2)O for 28 days. Quantitative proton nuclear magnetic resonance spectroscopy was used to determine the residual Me(2)SO concentration in the equilibration solutions from which Me(2)SO tissue concentrations were calculated. RESULTS: After thawing, the mean Me(2)SO concentration in the valve conduit was 0.302 +/- 0.081 M. The decellularization process resulted in a stepwise reduction in the Me(2)SO concentration to less than 8.56 x 10(-5) +/- 9 x 10(-5) M (P = 0.02). The diffusion coefficient was 2.5 x 10(-6) cm(2)/s. CONCLUSIONS: Our study demonstrates that Me(2)SO is effectively washed out of the aortic valve conduit during decellularization, resulting in a final concentration that is several orders of magnitude less than Me(2)SO concentrations reported to alter cell function.     

骨软骨组织工程支架的研究现状及发展趋势

目前,随着骨软骨组织工程的发展,为临床上骨软骨缺损的修复带来了新希望。应用自体细胞、支架、生长因子可以修复骨、软骨的缺损;选取具有生物相容性和可吸收性的复合支架可为细胞提供暂时的支持、黏附、生长环境,促进骨软骨缺损的修复。就骨软骨组织工程支架的分类、特性、应用以及存在的问题和发展趋势作一综述。     

Influence of nanopatterns on endothelial cell adhesion: Enhanced cell retention under shear stress

In this study, nanopatterned crosslinked films of collagen Type I were seeded with human microvascular endothelial cells and tested for their suitability for vascular tissue engineering. Since the films will be rolled into tubes with concentric layers of collagen, nutrient transfer through the collagen films is quite crucial. Molecular diffusivity through the collagen films, cell viability, cell proliferation and cell retention following shear stress were studied. Cells were seeded onto linearly nanogrooved films (groove widths of 332.5, 500 and 650 nm), with the grooves aligned in the direction of flow. The nanopatterns did not affect cell proliferation or initial cell alignment; however, they significantly affected cell retention under fluid flow. While cell retention on unpatterned films was 35 ± 10%, it was 75 ± 4% on 332.5 nm patterned films and even higher, 91 ± 5%, on 650 nm patterned films. The films were found to have diffusion coefficients of ca. 10⁻⁶ cm² s⁻¹ for O₂ and 4-acetaminophenol, which is comparable to that observed in natural tissues. This constitutes another positive asset of these films for consideration as a scaffold material for vascular tissue engineering.