New perspectives for articular cartilage repair treatment through tissue engineering: A contemporary review

In this paper review we describe benefits and disadvantages of the established methods of cartilage regeneration that seem to have a better long-term effectiveness.We illustrated the anatomical aspect of the knee joint cartilage, the current state of cartilage tissue engineering, through mesenchymal stem cells and biomaterials,and in conclusion we provide a short overview on the rehabilitation after articular cartilage repair procedures.Adult articular cartilage has low capacity to repair itself,and thus even minor injuries may lead to progressive damage and osteoarthritic joint degeneration, result-ing in significant pain and disability. Numerous efforts have been made to develop tissue-engineered grafts or patches to repair focal chondral and osteochondral defects, and to date several researchers aim to implement clinical application of cell-based therapies for cartilage repair. A literature review was conducted on PubM ed, Scopus and Google Scholar using appropriate keywords, examining the current literature on the wellknown tissue engineering methods for the treatment of knee osteoarthritis.

Functionalized Hydrogels for Articular Cartilage Tissue Engineering

Articular cartilage(AC)is an avascular and flexible connective tissue located on the bone surface in the diarthrodial joints.AC defects are common in the knees of young and physically active individuals.Because of the lack of suitable tissue-engineered artificial matrices,current therapies for AC defects,espe-cially full-thickness AC defects and osteochondral interfaces,fail to replace or regenerate damaged carti-lage adequately.With rapid research and development advancements in AC tissue engineering(ACTE),functionalized hydrogels have emerged as promising cartilage matrix substitutes because of their favor-able biomechanical properties,water content,swelling ability,cytocompatibility,biodegradability,and lubricating behaviors.They can be rationally designed and conveniently tuned to simulate the extracel-lular matrix of cartilage.This article briefly introduces the composition,structure,and function of AC and its defects,followed by a comprehensive review of the exquisite(bio)design and(bio)fabrication of func-tionalized hydrogels for AC repair.Finally,we summarize the challenges encountered in functionalized hydrogel-based strategies for ACTE both in vivo and in vitro and the future directions for clinical translation.

A Novel Biomaterial for Cartilage Repair Generated by Self-Assembly: Creation of a Self-Organized Articular Cartilage-Like Tissue

Recently, attention has been drawn to tissue engineering and other novel techniques aimed at reconstruction of the joint. Regarding articular cartilage tissue engineering, three-dimensional materials created in vitro by cultivation of autologous chondrocytes or mesenchymal stem cells with a collagen gel have been implanted to replace defective parts of the articular cartilage in limited cases with the diseases such as trauma or arthritis. However, several passages of chondrocyte culture are required to obtain a sufficient number of cells for tissue engineering. Additionally, several other problems arise including dedifferentiation of chondrocytes during cell culture, which need to be solved from a viewpoint of cellular resources. The purpose of our study is to create a novel biomaterial possessing functions and structures comparable to native hyaline articular cartilage by utilizing the physicochemical properties of the cartilage matrix components themselves, in other words, employing a self-assembly technique instead of using chondrocytes to produce cartilage matrices eventually leading to articular cartilage tissue formation. We verified the conditions and accuracy of the self-organization process and analyzed the resulting micro structure using electron beam microscopy in order to study the technique involved in the self-organization which would be applicable to creation of cartilage-like tissue. We demonstrated that self-assembly of several cartilage components including type II collagen, proteoglycan and hyaluronic acid could construct self-assembled cartilage-like tissues characterized by nano composite structures comparable to human articular cartilage and by low friction coefficients as small as those of native cartilage.

Research Progress of Osteochondral Composite Scaffolds in Tissue Engineering Cartilage Repair

Repair and regeneration of articular cartilage has always been a major challenge in the medical field due to its peculiar structure(e.g.sparsely distributed chondrocytes,no blood supply).Cartilage tissue engineering is one promising strategy for cartilage repair,however,one critical issue for cartilage tissue engineering is the integration between tissue-engineered and native cartilage.In recent years,osteochondral tissue engineering has attracted growing interest for overcoming this problem.Herein,we review the development of osteochondral tissue engineering.Firstly,currently used seed cells in osteochondral tissue engineering will be described.Secondly,several types of scaffolds and their(dis)advantage for osteochondral tissue engineering will be introduced.Thirdly,the growth factors currently used in osteochondral tissue engineering will be presented and discussed.

Repair effect of articular cartilage defects by nitric oxide synthase inhibitor

Objective To discuss repairing effects of articular cartilage defects by nitric oxide synthase inhibitor (S methylisothiourea, SMT), and explore the role of nitric oxide in cartilage repair. Methods Full-thickness defects of cartilage were created in the intercondylar trochlear groove of femur of thirty-six adult New Zealand white rabbits, and were divided into three gorups. Twenty-four defects were untreated as the control, twenty-four were filled with fibrin glue and impregnated with rhBMP AS rhBMP group, the rest twenty-four were filled with fibrin glue and impregnated with rhBMP, and hypodermic injection with SMT as SMT group. The animals were sacrified at sixteen weeks postoperatively, and the gross appearance of the defect was estimated. The repair tissue was examined histologically and was evaluated according to the grading scale of histology. The amount of released NO and the activities of nitric oxide synthase(NOS) were examined by chemical colorimetry. The distribution of type-Ⅰ , Ⅱ

Morphological MRI and T2 mapping of cartilage repair tissue after mosaicplasty with tissue-engineered cartilage in a pig model

The aim of this study was to evaluate the efficacy of mosaicplasty with tissue-engineered cartilage for the treatment of osteochondral defects in a pig model with advanced MR technique. Eight adolescent miniature pigs were used. The right knee underwent mosaicplasty with tissue-engineered cartilage for treatment of focal osteochondral defects, while the left knee was repaired via single mosaicplasty as controls. At 6, 12, 18 and 26 weeks after surgery, repair tissue was evaluated by magnetic resonance imaging （MRI） with the cartilage repair tissue （MOCART） scoring system and T2 mapping. Then, the results of MRI for 26 weeks were compared with findings of macroscopic and histologic studies. The MOCART scores showed that the repaired tissue of the tissue-engineered cartilage group was statistically better than that of controls （P 〈 0.001）. A significant correlation was found between macroscopic and MOCART scores （P 〈 0.001）. Comparable mean T2 values were found between adjacent cartilage and repair tissue in the experimental group （P 〉 0.05）. For zonal T2 value evaluation, there were no significant zonal T2 differences for repair tissue in controls （P 〉 0.05）. For the experimental group, zonal T2 variation was found in repair tissue （P 〈 0.05）. MRI, macroscopy and histology showed better repair results and bony incorporation in mosaicplasty with the tissue-engi- neered cartilage group than those of the single mosaicplasty group. Mosaicplasty with the tissue-engineered cartilage is a promising approach to repair osteochodndral defects. Morphological MRI and T2 mapping provide a non-invasive method for monitoring the maturation and integration of cartilage repair tissue in vivo.

Biomaterials for repair and regeneration of the cartilage tissue

The repair and regeneration of the diseases and damaged cartilage tissue are one of the most challenging issues in the field of tissue engineering and regenerative medicine. As the cartilage is a non-vascularized and comparatively acellular connective tissue, its ability to the self-restoration is limited to a large extent. Although there is a countless deal of experimental documents on this field, no quantifiable cure exists to bring back the healthy organization and efficacy of the impaired articular cartilage. Tissue reformative approaches have been of excessive curiosity in restoring injured cartilage. Bioengineering of the cartilage has progressed from the cartilage focal damages treatment to bioengineering tactics progress aiming the osteoarthritis procedures. The main focus of the present study is on the diverse potential development of strategies such as various categories of biomaterials applied in the reconstruction of the cartilage tissue.

Expression of Transforming Growth Factor β_(1) in Mesenchymal Stem Cells: Potential Utility in Molecular Tissue Engineering for Osteochondral Repair

The feasibility of using gene therapy to treat full-thickness articular cartilage defects was investigated with respect to the transfection and expression of exogenous transforming growth factor(TGF)-β_(1)genes in bone marrow-derived mesenchymal stem cells(MSCs)in vitro.The full-length rat TGF-β_(1)cDNA was transfected to MSCs mediated by lipofectamine and then selected with G418,a synthetic neomycin analog.The transient and stable expression of TGF-β_(1)by MSCs was detected by using immunohistochemical staining.The lipofectamine-mediated gene therapy efficiently transfected MSCs in vitro with the TGF-β_(1)gene causing a marked up-regulation in TGF-β_(1)expression as compared with the vector-transfected control groups,and the increased expression persisted for at least 4 weeks after selected with G418.It was suggested that bone marrow-derived MSCs were susceptible to in vitro lipofectamine mediated TGF-β_(1)gene transfer and that transgene expression persisted for at least 4 weeks.Having successfully combined the existing techniques of tissue engineering with the novel possibilities offered by modern gene transfer technology,an innovative concept,i.e.molecular tissue engineering,are put forward for the first time.As a new branch of tissue engineering,it represents both a new area and an important trend in research.Using this technique,we have a new powerful tool with which:(1)to modify the functional biology of articular tissue repair along defined pathways of growth and differentiation and(2)to affect a better repair of full-thickness articular cartilage defects that occur as a result of injury and osteoarthritis.

Study on the Microstructure of Human Articular Cartilage/Bone Interface

For improving the theory of gradient microstructure of cartilage/bone interface, human distal femurs were studied. Scanning Electron Microscope （SEM）, histological sections and MicroCT were used to observe, measure and model the micro- structure of cartilage/bone interface. The results showed that the cartilage/bone interface is in a hierarchical structure which is composed of four different tissue layers. The interlocking of hyaline cartilage and calcified cartilage and that of calcified car- tilage and subchondral bone are in the manner of＂protrusion-pore＂ with average diameter of 17.0 gm and 34.1 lam respectively. In addition, the cancellous bone under the cartilage is also formed by four layer hierarchical structure, and the adjacent layers are connected by bone trabecula in the shape of H, I and Y, forming a complex interwoven network structure. Finally, the simplified structure model of the cartilage/bone interface was proposed according to the natural articular cartilage/bone interface. The simplified model is a 4-layer gradient biomimetic structure, which corresponds to four different tissues of natural cartilage/bone interface. The results of this work would be beneficial to the design of bionic scaffold for the tissue engineering of articular cartilage/bone.

Repair of articular cartilage defects in rabbits through tissue-engineered cartilage constructed with chitosan hydrogel and chondrocytes

Objective： In our previous work, we prepared a type of chitosan hydrogel with excellent biocompatibility. In this study, tissue-engineered cartilage constructed with this chitosan hydrogel and costal chondrocytes was used to repair the articular cartilage defects. Methods： Chitosan hydrogels were prepared with a crosslinker formed by combining 1,6-diisocyanatohexane and polyethylene glycol. Chitosan hydrogel scaffold was seeded with rabbit chondrocytes that had been cultured for one week in vitro to form the preliminary tissue-engineered cartilage. This preliminary tissue-engineered cartilage was then transplanted into the defective rabbit articular cartilage. There were three treatment groups： the experimental group received preliminary tissue-engineered cartilage; the blank group received pure chitosan hydrogels; and, the control group had received no implantation. The knee joints were harvested at predetermined time. The repaired cartilage was analyzed through gross morphology, histologically and immunohistochemically. The repairs were scored according to the international cartilage repair society （ICRS） standard. Results： The gross morphology results suggested that the defects were repaired completely in the experimental group after twelve weeks. The regenerated tissue connected closely with subchondral bone and the boundary with normal tissue was fuzzy. The cartilage lacuna in the regenerated tissue was similar to normal cartilage lacuna. The results of ICRS gross and histological grading showed that there were significant differences among the three groups （P〈0.05）. Conclusions： Chondrocytes implanted in the scaffold can adhere, proliferate, and secrete extracellular matrix. The novel tissue-engineered cartilage constructed in our research can completely repair the structure of damaged articular cartilage.

Molecular Tissue Engineering: Applications for Modulation of Mesenchymal Stem Cells Proliferation by Transforming Growth Factor β_1 Gene Transfer

The effect of transforming growth factor β 1 (TGF β 1 ) gene transfection on the proliferation of bone marrow derived mesenchymal stem cells (MSC S ) and the mechanism was investigated to provide basis for accelerating articular cartilage repairing using molecular tissue engineering technology. TGF β 1 gene at different doses was transduced into the rat bone marrow derived MSCs to examine the effects of TGF β 1 gene transfection on MSCs DNA synthesis, cell cycle kinetics and the expression of proliferating cell nuclear antigen (PCNA). The results showed that 3 μl lipofectamine mediated 1 μg TGF β 1 gene transfection could effectively promote the proliferation of MSCs best; Under this condition (DNA/Lipofectamine=1μg/3μl), flow cytometry and immunohistochemical analyses revealed a significant increase in the 3 H incorporation, DNA content in S phase and the expression of PCNA. Transfection of gene encoding TGF β 1 could induce the cells at G0/G1 phase to S1 phase, modulate the replication of DNA through the enhancement of the PCNA expression, increase the content of DNA at S1 phase and promote the proliferation of MSCs. This new molecular tissue engineering approach could be of potential benefit to enhance the repair of damaged articular cartilage, especially those caused by degenerative joint diseases.

Effect of porosities of bilayered porous scaffolds on spontaneous osteochondral repair in cartilage tissue engineering

Poly(lactide-co-glycolide)-bilayered scaffolds with the same porosity or different ones on the two layers were fabricated,and the porosity effect on in vivo repairing of the osteochondral defect was examined in a comparative way for the first time.The constructs of scaffolds and bone marrow-derived mesenchymal stem cells were implanted into pre-created osteochondral defects in the femoral condyle of New Zealand white rabbits.After 12 weeks,all experimental groups exhibited good cartilage repairing according to macroscopic appearance,cross-section view,haematoxylin and eosin staining,toluidine blue staining,immunohistochemical staining and real-time polymerase chain reaction of characteristic genes.The group of 92%porosity in the cartilage layer and 77%porosity in the bone layer resulted in the best efficacy,which was understood by more biomechanical mimicking of the natural cartilage and subchondral bone.This study illustrates unambiguously that cartilage tissue engineering allows for a wide range of scaffold porosity,yet some porosity group is optimal.It is also revealed that the biomechanical matching with the natural composite tissue should be taken into consideration in the design of practical biomaterials,which is especially important for porosities of a multi-compartment scaffold concerning connected tissues.

神经生长因子对骨骼形成及骨疾病的影响

背景:神经生长因子在骨骼的生理和病理进程中发挥了重要作用,系统性分析神经生长因子对骨组织的影响在组织工程及临床治疗两方面都具有重要意义。目的:探究神经生长因子通过骨组织细胞和骨神经-血管耦合等途径调控骨形成的过程,同时研究神经生长因子在骨相关疾病病理进程中的作用。方法:在中国知网、万方、PubMed数据库以“神经生长因子,TrkA,骨,软骨”为中文检索词,以“Nerve growth factor,TrkA,NGF,bone,cartilage”为英文检索词进行文献检索,共检索到2 925篇文献。经过筛选后纳入116篇文献进行归纳总结,撰写综述。结果与结论:神经生长因子既可在骨、软骨、神经、血管等组织细胞中表达,又可作用于这些细胞发挥调控作用。通过多种分泌调控方式,神经生长因子在骨组织内部和骨、神经、血管组织间发挥信号传导作用。通过促进骨髓间充质干细胞的增殖、分化,神经生长因子可促进骨形成及骨修复。神经生长因子介导的破骨细胞生成说明其对骨组织具有多向调控作用。同时,神经生长因子与多种骨科疾病的发生发展高度相关,可能提供新的临床治疗思路。对神经生长因子的研究是了解骨骼生理及病理变化的重要方向之一。

组织工程技术修复颞下颌关节:问题与挑战

背景:颞下颌关节疾病的传统疗法受限于疾病严重程度和个体差异。相比之下,组织工程作为一种新兴治疗方法,可以根据患者具体情况定制个性化治疗方案,减少手术过程中的不确定性,提高治疗效果。目的:综述组织工程修复颞下颌关节的最新研究成果和进展。方法:以“颞下颌关节,组织工程,种子细胞,支架,生长因子,动物模型”为中文检索词,以“temporomandibular joint,tissue engineering,seed cell,scaffold,growth factor,animal model”为英文检索词,分别在PubMed数据库和中国知网进行文献检索,检索时限为各数据库建库时间至2024年3月。通过分析和阅读文献进行筛选,按照排除筛选标准纳入文献,最终纳入57篇文献进行综述。结果与结论:(1)随着生物学、材料学与工程学等技术的发展,颞下颌关节组织工程己取得较大进展,例如种子细胞的筛选、新型支架的开发、生长因子作用机制的探索、多种动物模型的构建等,目前大多数研究尚处于体外实验阶段,动物实验等体内研究尚未大规模开展,组织工程修复颞下颌关节的临床应用还需更多证据支持。(2)尽管颞下颌关节组织工程研究仍存在许多问题和挑战等待解决,依然展现出广阔的临床应用前景,有望在将来成为颞下颌关节疾病出色高效的治疗方式。

Advanced hydrogels for the repair of cartilage defects and regeneration

Cartilage defects are one of the most common symptoms of osteoarthritis(OA),a degenerative disease that affects millions of people world-wide and places a significant socio-economic burden on society.Hydrogels,which are a class of biomaterials that are elastic,and display smooth surfaces while exhibiting high water content,are promising candidates for cartilage regeneration.In recent years,various kinds of hydrogels have been developed and applied for the repair of cartilage defects in vitro or in vivo,some of which are hopeful to enter clinical trials.In this review,recent research findings and developments of hydrogels for cartilage defects repair are summarized.We discuss the principle of cartilage regeneration,and outline the requirements that have to be fulfilled for the deployment of hydrogels for medical applications.We also highlight the development of advanced hydrogels with tailored properties for different kinds of cartilage defects to meet the requirements of cartilage tissue engineering and precision medicine.

3D-printed fish gelatin scaffolds for cartilage tissue engineering

Knee osteoarthritis is a chronic disease caused by the deterioration of the knee joint due to various factors such as aging,trauma,and obesity,and the nonrenewable nature of the injured cartilage makes the treatment of osteoarthritis challenging.Here,we present a three-dimensional(3D)printed porous multilayer scaffold based on cold-water fish skin gelatin for osteoarticular cartilage regeneration.To make the scaffold,cold-water fish skin gelatin was combined with sodium alginate to increase viscosity,printability,and mechanical strength,and the hybrid hydrogel was printed according to a pre-designed specific structure using 3D printing technology.Then,the printed scaffolds underwent a double-crosslinking process to enhance their mechanical strength even further.These scaffolds mimic the structure of the original cartilage network in a way that allows chondrocytes to adhere,proliferate,and communicate with each other,transport nutrients,and prevent further damage to the joint.More importantly,we found that cold-water fish gelatin scaffolds were nonimmunogenic,nontoxic,and biodegradable.We also implanted the scaffold into defective rat cartilage for 12 weeks and achieved satisfactory repair results in this animal model.Thus,cold-water fish skin gelatin scaffolds may have broad application potential in regenerative medicine.

Urine-derived stem cells:applications in skin,bone and articular cartilage repair

As an emerging type of adult stem cell featuring non-invasive acquisition,urine-derived stem cells(USCs)have shown great potential for applications in tissue engineering and regenerative medicine.With a growing amount of research on the topic,the effectiveness of USCs in various disease models has been shown and the underlying mechanisms have also been explored,though many aspects still remain unclear.In this review,we aim to provide an up-to-date overview of the biological characteristics of USCs and their applications in skin,bone and articular cartilage repair.In addition to the identification procedure of USCs,we also summarize current knowledge of the underlying repair mechanisms and application modes of USCs.Potential concerns and perspectives have also been summarized.

The application of ECM-derived biomaterials in cartilage tissue engineering

Given the tremendous increase in the risks of cartilage defects in the sports and aging population,current treatments are limited,and new repair strategies are needed.Cartilage tissue engineering(CTE)is a promising approach to handle this burden and several fabrication technologies and biomaterials have been developed these years.The extracellular matrix(ECM)of cartilage consists of a tissue-specific 3D microenvironment with excellent biomechanical and biochemical properties,which regulates cell proliferation,adhesion,migration,and differentiation,thus attracting a great deal of attention to the rapid development of CTE based on ECM components.New generations of biomaterials are being developed rapidly for use as scaffolds to mimic the natural ECM environment.In this review,we discuss such CTE scaffolds based on ECM-derived biomaterials by reviewing the biomaterials for CTE,the applications in different scaffolds and their processing approaches,as well as the current clinical applications of those ECM-based CTE scaffolds.

纳米复合水凝胶在骨关节炎治疗中的优势与特征

背景:纳米复合水凝胶在骨关节炎治疗中有很大的研究前景和应用潜力。目的:综述纳米复合水凝胶在骨关节炎及软骨修复中的研究进展。方法:检索中国知网和PubMed等数据库,英文检索词为“nanocomposite hydrogel,nanogel,osteoarthritis,cartilage,physical encapsulation,electrostatic interaction,covalent crosslinking”,中文检索词为“纳米复合水凝胶,纳米水凝胶,骨关节炎,软骨,物理包覆,物理包载,静电作用,共价交联”。根据纳入与排除标准对所有文章进行初筛后,保留相关性较高的71篇文章进行综述。结果与结论:在细胞或动物实验中,纳米复合水凝胶具有改善骨关节炎的效果。纳米复合水凝胶可以从改善关节间力学环境、搭载靶向药物、促进种子细胞软骨化等方面加速软骨修复,改善骨关节炎症内环境,达到治疗骨关节炎的目的。目前纳米复合水凝胶在骨关节炎疾病中的研究仍有巨大的发挥空间,继续深入材料制备研究,积极开展细胞、动物实验将有望为临床治疗骨关节炎开辟新途径。