Feasibility of a self‐assembling peptide hydrogel scaffold for meniscal defect: An in vivo study in a rabbit model

The inner avascular zone of the meniscus has limited healing capacity as the area is poorly vascularized. Although peptide hydrogels have been reported to regenerate bone and cartilage, their effect on meniscus regeneration remains unknown. We tested whether the self‐assembling peptide hydrogel scaffold KI24RGDS stays in the meniscal lesion and facilitates meniscal repair and regeneration in an induced rabbit meniscal defect model. Full‐thickness (2.0 mm diameter) cylindrical defects were introduced into the inner avascular zones of the anterior portions of the medial menisci of rabbit knees (n = 40). Right knee defects were left empty (control group) while the left knee defects were transplanted with peptide hydrogel (KI24RGDS group). Macroscopic meniscus scores were significantly higher in the KI24RGDS group than in the control group at 2, 4, and 8 weeks after surgery. Histological examinations including quantitative and qualitative scores indicated that compared with the control group, the reparative tissue in the meniscus was significantly enhanced in the KI24RGDS group at 2, 4, 8, and 12 weeks after surgery. Immunohistochemical staining showed that the reparative tissue induced by KI24RGDS at 12 weeks postimplantation was positive for Type I and II collagen. KI24RGDS is highly biocompatible and biodegradable, with strong stiffness, and a three dimensional structure mimicking native extracellular matrix and RGDS sequences that enhance cell adhesion and proliferation. This in vivo study demonstrated that KI24RGDS remained in the meniscal lesion and facilitated the repair and regeneration in a rabbit meniscal defect model.     

Capsid protein identification and analysis of mature Triatoma virus (TrV) virions and naturally occurring empty particles

Triatoma virus (TrV) is a non-enveloped + ssRNA virus belonging to the insect virus family Dicistroviridae. Mass spectrometry (MS) and gel electrophoresis were used to detect the previously elusive capsid protein VP4. Its cleavage sites were established by sequencing the N-terminus of the protein precursor and MS, and its stoichiometry with respect to the other major capsid proteins (VP1-3) was found to be 1:1. We also characterized the polypeptides comprising the naturally occurring non-infectious empty capsids, i.e., RNA-free TrV particles. The empty particles were composed of VP0-VP3 plus at least seven additional polypeptides, which were identified as products of the capsid precursor polyprotein. We conclude that VP4 protein appears as a product of RNA encapsidation, and that defective processing of capsid proteins precludes genome encapsidation.     

Overexpression of hUMP1/POMP proteasome accessory protein enhances proteasome-mediated antioxidant defence

The proteasome is the major cellular proteolytic machinery. It is involved in the regulation of various pathways via the selective degradation of either short-lived normal proteins or damaged proteins permitting the cellular detoxification. Proteasome has impaired function during several biological processes, including aging and diseases; however, it can be activated through overexpression of beta(5)- or beta(1)-subunits, resulting to enhanced survival and extended lifespan. In the current study, we have investigated proteasomal up-regulation via overexpression of hUMP1/POMP protein, the known accessory factor for proteasome assembly in humans. hUMP1/POMP overexpressing fibroblasts have increased levels of functional proteasome and enhanced capacity to cope better and faster with various oxidative stressors. These data highlight hUMP1/POMP role in proteasome assembly and further strengthen the prospect of genetic manipulation of the proteasomal system.     

基于均匀设计的中药有效组分复方配伍研究

目的探索基于均匀设计的中药抗氧化有效组分复方的研究分析方法。方法采用均匀设计和改进最小角回归分析,对甘草总黄酮、银杏叶提取物、淫羊藿总黄酮和黄芪总苷组成的中药组分复方不同配比体外清除DPPH自由基的作用进行研究。结果通过分析获得了中药组分配伍清除DPPH的回归方程,优化组合后进行药效学验证,结果显示该中药组分配伍最佳剂量组合为甘草总黄酮0.8mg/ml、银杏叶提取物3.144mg/ml、淫羊藿总黄酮0.024mg/ml和黄芪总苷0.036mg/ml。结论上述中药组分配伍后能有效清除DPPH自由基;本实验采用的均匀设计结合改进最小角回归分析适合"非线性、小样本"生物实验数据数据分析,为筛选评价抗氧化中药有效组分复方提供了合适的研究方法。     

Redefining tissue engineering for nanomedicine in ophthalmology

Working at the nanoscale means to completely rethink how to approach engineering in the body in general and in the eye in particular. In nanomedicine, tissue engineering is the ability to influence an environment either by adding, subtracting or manipulating that environment to allow it to be more conducive for its purpose. The goal is to function at the optimum state, or to return to that optimum state. Additive tissue engineering replaces cells or tissue, or tries to get something to grow that is no longer there. Arrestive tissue engineering tries to stop aberrant growth which, if left uncontrolled, would result in a decrease in function. Nano delivery of therapeutics can perform both additive and arrestive functions influencing the environment either way, depending on the targeting. By manipulating the environment at the nanoscale, the rate and distribution of healing can be controlled. It infers that potential applications of nanomedicine in ophthalmology include procedures, such as corneal endothelial cell transplantation, single retinal ganglion cell repair, check of retinal ganglion cell viability, building of nanofibre scaffolds, such as self‐assembling peptides, to create a scaffold‐like tissue‐bridging structure to provide a framework for axonal regeneration in the case of optic nerve reconnection or eye transplantation, and ocular drug delivery. Examples of potential arrestive therapies include gene‐related treatment modalities to inhibit intraocular neovascularization and to block retinal cell apoptosis. Looking towards the future, this review focuses on how nanoscale tissue engineering can be and is being used to influence that local environment.     

Self‐Assembling of Block Copolymers with Alternative Solvents

Block copolymer (BCP) lithography is one of the most technologically intriguing and scientifically interesting strategies for achieving nanometer‐sized features. This method usually exploits toluene as solvent for the deposition of BCPs in all the processing steps. However, this chemical has some technical disadvantages, such as high toxicity and hygroscopicity. The first aspect can limit its use on the industrial scale because of the protocols on the environmental and operator risks, while the second causes aging effects that can alter the results. In order to overcome these intrinsic limitations, a BCP self‐assembly (BCP‐SA) strategy is presented by using alternative deposition solvents in place of toluene. A preliminary study, based on the physical characteristics, such as volatility, polarity, and hygroscopicity, is carried out to explore two new alternative solvents, ethyl acetate and tetrahydrofuran. The effects on the BCP‐SA due to the new solvents are studied by SEM analysis supported by suitable software for the images elaboration. The results achieved show very promising outcomes for the polymer solutions obtained with ethyl acetate, in terms of uniformity of geometrical features, ordered areas extension, and homogeneity of the pattern obtained, making this chemical a good alternative to toluene.     

Effects of confinement on the mechanical properties of self‐assembled articular cartilage constructs in the direction orthogonal to the confinement surface

This study examined the effects of radial confinement and passive axial compression‐induced vertical confinement, on the biomechanical, biochemical, and histological properties of self‐assembled chondrocyte constructs. The self‐assembled constructs, engineered without the use of an exogenous scaffold, exhibited significant increases in stiffness in the direction orthogonal to that of the confinement surface. With radial confinement, the significantly increased aggregate modulus was accompanied by increased collagen organization in the direction perpendicular to the articular surface, with no change in collagen or glycosaminoglycan (GAG) content. Additionally, radial confinement was most beneficial when applied before 2 weeks. With passive axial compression, the significantly increased Young's modulus and ultimate tensile strength were accompanied by a significant increase in collagen production. This study is the first to demonstrate the beneficial effects of confinement on tissue engineered constructs in the direction orthogonal to that of the confinement surface. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:238–246, 2008