纳米银-胶原蛋白组织工程周围神经支架的构建及其理化性能的检测

目的 探讨纳米银-胶原蛋白组织工程周围神经支架的构建及其理化性能和生物相容性.方法 采用不同浓度纳米银溶液构建含不同浓度纳米银(1、2、3、4、5、6 mg/L)的胶原蛋白组织工程支架,对照组仅加入不含纳米银的等量纯水.分别以扫描电镜观察其横截面和纵截面孔径结构,测定微拉伸强度.采用5只SD仔鼠进行纳米银-胶原蛋白支架细胞毒性实验,8只雄性成年SD大鼠进行支架体内降解实验,12只雄性成年SD大鼠行纳米银体内蓄积毒性测试.逐步按照空间结构以及在模拟体内环境下的多种理化特性筛选最佳纳米银含量的纳米银-胶原蛋白材料,构建周围神经支架.结果 纳米银含量为l、2 mg/L的纳米银-胶原蛋白支架内部孔径结构高度仿生,其中2 mg/L纳米银含量组的支架抗拉伸强度达到0.22 MPa,优于其他测试组.采用含2 mg/L纳米银支架材料制作薄膜行雪旺细胞培养证实该支架材料无神经细胞毒性.体内降解实验显示该组织工程支架从植入体内开始缓慢发生降解,4个月后可以完全降解.纳米银体内蓄积毒性测试显示在支架植入体内直至完全降解过程中,脑、脊髓、肝和肾脏银元素含量均低于l ng/mL,不存在蓄积毒性.结论 使用含2mg/L纳米银的胶原蛋白周围神经组织工程支架不仅在内部空间结构上可高度仿生周围神经,且具有较好的抗拉伸强度、在体内可完全降解、无细胞毒性和银蓄积毒性等优点.     

Current concepts in gene therapy of the musculoskeletal system

The purpose of this article is to review the remarkable progress in the field of musculoskeletal system gene therapy. Since the introduction of this concept 15 years much of the preclinical and clinical data have emerged. The original target, rheumatoid arthritis, has been subjected to clinical phase II efficacy protocol, and osteoarthritis gene therapy efficacy is being thoroughly investigated in various animal models. The most promising area of research in this field however, is the tissue repair, because it doesn't require prolonged period of gene expression, local delivery is reasonably simple and it avoids substantial risk associated with systemic delivery, and levels of gene expression don't need to be so finely regulated. Gene transfer is successfully being used to aid the repair and regeneration of bone, cartilage, ligament tendon, meniscus and intervertebral disc. Other potential applications of gene therapy in musculoskeletal system include osteoporosis, aseptic loosening, genetic diseases and tumors. Highly encouraging data gained from these studies have confirmed that gene therapy is a promising therapeutic solution to treat various musculoskeletal system disorders.     

Current concepts in tissue engineering technique for repair of cartilage defect

Hunter's observation in 1743 that cartilage "once destroyed, is not repaired," has not essentially changed for 250 years. At present, there is no well-established procedure for the repair of cartilage defect with articular cartilage, which has the same biochemical and biomechanical properties as the surrounding normal intact cartilage. In 1994, transplantation of human autologous chondrocytes in suspension, as reported by Brittberg et al., provided a potential procedure for articular cartilage repair. We have improved their procedure and developed a new technique which creates new cartilage-like tissue by cultivating autologous chondrocytes embedded in Atelocollagen gel for 3 weeks before transplantation. These improvements maintained the chondrocyte phenotype, evenly distributed chondrocytes throughout the osteochondral defects, and decreased the risk of leakage of grafted chondrocytes into the defects. Good clinical results suggest that this technique should be a promising procedure for repairing articular cartilage defect.     

天然神经细胞外基质桥接周围神经缺损的实验研究

周围神经缺损的修复一直是困扰临床医生的一个难题,为此我们尝试了用组织工程方法修复周围神经缺损的实验研究,旨在了解天然神经细胞外基质（ＮａｔｕｒｅＥｘｔｒａｃｅｌｕｌａｒＭａｔｒｉｘ,ＮＥＣＭ）在神经再生中的作用,为临床修复周围神经缺损寻求新的替代材料。实验用ＳＤ大鼠４８只各组１２只分别用ＮＥＣＭ,自体坐骨神经;腹壁浅静脉桥接坐骨神经１０ｍｍ缺损,空白对照组缺损旷置。术后８周,观察运动功能、再生神经形态学及ＨＲＰ逆行标记脊髓前角运动神经元情况表明,上述指标ＮＥＣＭ组与自体神经移植组无显著差异（Ｐ＞０．０５）优于静脉移植组（Ｐ＜０．０１）。该移植体无免疫排斥反应,具有良好的生物相容性,且富含神经再生所需生物要素,为神经再生构成了良好的微环境条件,因此在临床修复神经缺损有潜在的实用价值。     

Diffusion-weighted MR imaging in musculoskeletal diseases: Current concepts

MR imaging is currently regarded as a pivotal technique for the assessment of a variety of musculoskeletal conditions. Diffusion-weighted MR imaging (DWI) is a relatively recent sequence that provides information on the degree of cellularity of lesions. Apparent diffusion coefficient (ADC) value provides information on the movement of water molecules outside the cells. The literature contains many studies that have evaluated the role of DWI in musculoskeletal diseases. However, to date they yielded conflicting results on the use and the diagnostic capabilities of DWI in the area of musculoskeletal diseases. However, many of them have showed that DWI is a useful technique for the evaluation of the extent of the disease in a subset of musculoskeletal cancers. In terms of tissue characterization, DWI may be an adjunct to the more conventional MR imaging techniques but should be interpreted along with the signal of the lesion as observed on conventional sequences, especially in musculoskeletal cancers. Regarding the monitoring of response to therapy in cancer or inflammatory disease, the use of ADC value may represent a more reliable additional tool but must be compared to the initial ADC value of the lesions along with the knowledge of the actual therapy.     

Current concepts in peripheral nerve surgery

European Journal of Orthopaedic Surgery & Traumatology - The injuries of the peripheral nerves are relatively frequent. Some of them may lead to defects which cannot be repaired with direct...     

组织工程神经在修复周围神经缺损中的应用

周围神经缺损的修复与重建是当前神经领域的一大难题。目前，国内外学者已着力研究雪旺细胞和生物材料复合构建组织工程化人工神经，并将其与日益完善的显微外科技术结合起来，提高周围神经损伤的修复水平。本文结合国内外研究成果，对周围神经损伤修复的研究进行回顾，着重从组织工程方面阐述周围神经修复方法的现状与前景。     

Regeneration of the anterior cruciate ligament: Current strategies in tissue engineering

Recent advancements in the field of musculoskeletal tissue engineering have raised an increasing interest in the regeneration of the anterior cruciate ligament (ACL). It is the aim of this article to review the current research efforts and highlight promising tissue engineering strategies. The four main components of tissue engineering also apply in several ACL regeneration research efforts. Scaffolds from biological materials, biodegradable polymers and composite materials are used. The main cell sources are mesenchymal stem cells and ACL fibroblasts. In addition, growth factors and mechanical stimuli are applied. So far, the regenerated ACL constructs have been tested in a few animal studies and the results are encouraging. The different strategies, from in vitro ACL regeneration in bioreactor systems to bio-enhanced repair and regeneration, are under constant development. We expect considerable progress in the near future that will result in a realistic option for ACL surgery soon.     

Current concepts in end-to-side neurorrhaphy

In peripheral nerve injury, end-to-side neurorrhaphy involves coaptation of the distal stump of a transected nerve to the trunk of an adjacent donor nerve. It has been proposed as an alternative technique when the proximal stump of an injured nerve is unavailable or the nerve gap is too long to be bridged by a nerve graft. Experimental and clinical data suggests that end-to-side neurorrhaphy can provide satisfactory functional recovery for the recipient nerve, without any deterioration of the donor nerve function. The most accepted mechanism of nerve regeneration following end-to-side neurorrhaphy is collateral sprouting. The source of the regenerating axons traveling in the epineurium of the donor nerve is thought to be the proximal Ranvier's nodes at the site of end-to-side neurorrhaphy, however, histologic evidence is still lacking. Partial neurotomy of the donor nerve may enhance regeneration of motor neurons through end-to-side neurorrhaphy and reinnervation of motor targets.     

Current and future imaging of the peripheral nervous system

Peripheral nervous system (PNS) imaging is usually carried out by ultrasound and MRI. Thanks to its wide availability and excellent spatial resolution, ultrasound is a mature investigation with clearly established indications, particularly in entrapment syndromes and tumors. MRI is generally a second-line examination, which provides decisive additional information thanks to its excellent contrast resolution and its multiplanar abilities. This review describes the current methods for imaging the PNS, concentrating on acquisition techniques, normal results and basic pathological semiology. Ongoing and future developments are described in order to underline the forthcoming changes in this very dynamic field of musculoskeletal radiology.     

Basic concepts regarding fracture healing and the current options and future directions in managing bone fractures

Fracture healing is a complex physiological process, which involves a well‐orchestrated series of biological events. Repair of large bone defects resulting from trauma, tumours, osteitis, delayed unions, non‐unions, osteotomies, arthrodesis and multifragmentary fractures is a current challenge of surgeons and investigators. Different therapeutic modalities have been developed to enhance the healing response and fill the bone defects. Different types of growth factors, stem cells, natural grafts (autografts, allografts or xenografts) and biologic‐ and synthetic‐based tissue‐engineered scaffolds are some of the examples. Nevertheless, these organic and synthetic materials and therapeutic agents have some significant limitations, and there are still no well‐approved treatment modalities to meet all the expected requirements. Bone tissue engineering is a newer option than the traditional grafts and may overcome many limitations of the bone graft. To select an appropriate treatment strategy in achieving a successful and secure healing, more information concerning injuries of bones, their healing process and knowledge of the factors involved are required. The main goals of this work are to present different treatment modalities of the fractured bones and to explain how fractures normally heal and what factors interfere with fracture healing. This study provides an overview of the processes of fracture healing and discusses the current therapeutic strategies that have been claimed to be effective in accelerating fracture healing.     

Ex vivo method to visualize and quantify vascular networks in native and tissue engineered skin

Background and aims  Neovascularization plays a pivotal role in tissue engineering and tissue regeneration. However, reliable technologies to visualize and quantify blood vessel networks in target tissue areas are still pending. In this work, we introduce a new method which allows comparing vascularization levels in normal and tissue-engineered skin. Materials and methods  Normal skin was isolated, and vascular dermal regeneration was analyzed based on tissue transillumination and computerized digital segmentation. For tissue-engineered skin, a bilateral full skin defect was created in a nude mouse model and then covered with a commercially available scaffold for dermal regeneration. After 3 weeks, the whole skin (including scaffold for dermal regeneration) was harvested, and vascularization levels were analyzed. Results  The blood vessel network in the skin was better visualized by transillumination than by radio-angiographic studies, the gold standard for angiographies. After visualization, the whole vascular network was digitally segmented showing an excellent overlapping with the original pictures. Quantification over the digitally segmented picture was performed, and an index of vascularization area (VAI) and length (VLI) of the vessel network was obtained in target tissues. VAI/VLI ratio was calculated to obtain the vessel size index. Conclusions  We present a new technique which has several advantages compared to others, as animals do not require intravascular perfusions, total areas of interest can be quantitatively analyzed at once, and the same target tissue can be processed for further experimental analysis. This work was presented at the 10th European Conference of Scientists and Plastic Surgeons (ECSAPS). London, UK. September 2006.     

计算机辅助导航全膝关节置换术的当前概念和进展

全膝关节置换术(TKR)旨在重建胫股和髌股关节的稳定性,缓解疼痛,改善患者生活质量.计算机辅助导航系统的应用能够有效减少常规TKR手术下肢力线重建中的人为错误并改善手术结果.现有证据表明,应用计算机辅助导航系统能够显著减少术后机械轴和冠状位假体位置的异常值.此外,导航系统提供了常规手术无法获得的软组织平衡客观评估.应用...     

Upper extremity peripheral nerve anatomy: current concepts and applications

The nerve anatomy of the upper extremity is studied constantly through surgical findings, electrodiagnostic studies, and cadaveric dissections. Although it is recognized that the anatomy is not changing rapidly, knowledge of the anatomic relationships and their significance is increasing. The purpose of the current study is to provide a comprehensive analysis of the nerve anatomy of the upper extremity to include innervation patterns, critical landmarks, and clinical applications, with particular focus on recent contributions in the literature.     

The complementarity of the technical tools of tissue engineering and the concepts of artificial organs for the design of functional bioartificial tissues

Although tissue engineering uses powerful biological tools, it still has a weak conceptual foundation, which is restricted at the cell level. The design criteria at the cell level are not directly related with the tissue functions, and consequently, such functions cannot be implemented in bioartificial tissues with the currently used methods. On the contrary, the field of artificial organs focuses on the function of the artificial organs that are treated in the design as integral entities, instead of the optimization of the artificial organ components. The field of artificial organs has already developed and tested methodologies that are based on system concepts and mathematical-computational methods that connect the component properties with the desired global organ function. Such methodologies are needed in tissue engineering for the design of bioartificial tissues with tissue functions. Under the framework of biomedical engineering, artificial organs and tissue engineering do not present competitive approaches, but are rather complementary and should therefore design a common future for the benefit of patients.     

Cultured composite autografts as coverage for an extensive body surface area burn: case report and review of the technology

Cultured epithelial autografts (CEA) have been used as an adjunct in the surgical management of extensive thermal burns. Unfortunately, the lack of a dermal matrix makes CEA susceptible to infection, shearing forces and limits their incorporation into the burn wound. A cultured composite autograft (CCA) has been developed in which autologous keratinocytes and fibroblasts are surgically harvested from the burn patient's normal skin. These components are proliferated and then combined to form an epidermal and dermal matrix, grown to confluence then applied.

Standard wound coverage techniques as well as CCA technology were utilized for successful wound closure in a 12 yr-old female with an 81% third degree burn. After fascial excision and allograft coverage, autografts were placed on her posterior burns and then 7500 cm² of CCA was placed onto her anterior thorax, abdomen and lower extremities. Sixty percent of the burn was covered with CCA resulting in a success rate of 40%. No evidence of infection was noted, even in areas where CCA failed, although in those areas random epithelialization appeared to occur which then seemed to facilitate autograft placement. Early debridement and allografting followed by conventional autografts and CCA placement may provide an effective skin coverage strategy in patients with extensive deep burns.