不同来源间充质干细胞在膝关节软骨修复中的临床研究进展

近年来由于器官修复干细胞治疗技术的提出,使得不能自身修复的关节软骨成为研究热点之一,间充质干细胞对膝关节软骨修复已表现出明显的治疗优势。学者们临床上初步研究了不同来源的间充质干细胞膝关节软骨修复作用,并通过结合移植、软骨组织工程等技术提高了骨髓、脂肪、滑膜、脐带血等来源干细胞修复人类软骨效果,均取得了较好的临床疗效。不同干细胞来源不同各自会有一定的优缺点。目前临床研究仍处于试验阶段,尚无确切定论何种干细胞及何种技术处理最适合于人类软骨的修复。大规模和或结合新处理技术的临床试验以及远期疗效的验证,需要进一步临床深入研究。     

Update on mesenchymal stem cell therapies for cartilage disorders

Cartilage disorders, including focal cartilage lesions, are among the most common clinical problems in orthopedic practice. Left untreated, large focal lesions may result in progression to osteoarthritis, with tremendous impact on the quality of life of affected individuals. Current management strategies have shown only a modest degree of success, while several upcoming interventions signify better outcomes in the future. Among these, stem cell therapies have been suggested as a promising new era for cartilage disorders. Certain characteristics of the stem cells, such as their potential to differentiate but also to support healing made them a fruitful candidate for lesions in cartilage, a tissue with poor healing capacity. The aim of this editorial is to provide an update on the recent advancements in the field of stem cell therapy for the management of focal cartilage defects. Our goal is to present recent basic science advances and to present the potential of the use of stem cells in novel clinical interventions towards enhancement of the treatment armamentarium for cartilage lesions. Furthermore, we highlight some thoughts for the future of cartilage regeneration and repair and to explore future perspectives for the next steps in the field.     

Gene therapy for cartilage repair

AIM: Articular cartilage has very limited intrinsic healing capacity. Although numerous attempts to repair full-thickness articular cartilage defects have been conducted, no methods have successfully regenerated long-lasting hyaline cartilage. One of the most promising procedures for cartilage repair is tissue engineering accompanied by gene therapy. METHOD: With gene therapy, genes encoding for therapeutic growth factors can be expressed at a high level in the injured site for an extended period of time. Chondrocytes have been intensively studied for cell transplantation in articular cartilage defects. RESULTS: However, recent studies have shown that chondrocytes are not the only candidate for cartilage repair. Muscle-derived cells have been found capable of delivering genes and represent a good vehicle to deliver therapeutic genes to improve cartilage repair. More importantly, recent studies have suggested the presence of pluripotent stem cells in muscle-derived cells. CONCLUSION: New techniques of cell therapy and molecular medicine for the treatment of cartilage lesions are currently undergoing clinical trials. This paper will summarize the current status of gene therapy for cartilage repair and its future application.     

Editorial Commentary: Biological Cartilage Repair Technique—An “Effective,Accessible, and Safe” Surgical Solution for an Old Difficult Biological Problem

Achieving good long-term outcomes while treating chondral defects has always been a challenge. Several surgical techniques for regeneration of the articular cartilage have been proposed. Among them, osteochondral autograft transplantation and 2-step procedures such as autologous chondrocyte implantation have provided good results, promoting formation of new hyaline-like cartilage tissue, whereas other techniques such as microfracture result in fibrous cartilage and a less durable repair. Single-stage cell-based procedures are an attractive treatment option given the potential for cost savings and avoiding a second-stage procedure. We believe that 1-stage cartilage repair in the knee with a hyaluronic acid–based scaffold embedded with mesenchymal stem cells sourced from bone marrow aspirate concentrate has a prominent role in treating chondral defects because this is a simple technique that could improve the care of patients and be cost-effective in the near future.     

Injectable cultured bone marrow derived mesenchymal cells vs chondrocytes in the treatment of chondral defects of the knee – RCT with 6 years follow-up

Articular cartilage has unique biological and biomechanical characteristics. Damage to this tissue fails to heal spontaneously, leading to progressive arthritis. Cartilage repair techniques have been looked forward to in the treatment of significant cartilage injuries. Cell-based regenerative techniques like the two-staged cultured chondrocytes and single-stage mesenchymal cell transplantation have been tried with varying results and limitations. We study the outcomes of cultured bone marrow derived MSCs in the treatment of articular cartilage defects of the knee in comparison to autologous cultured chondrocyte implantation (ACI). Both cultured MSC and ACI treatment methods resulted in significant improvements in patient reported outcome measures (PROMs). There was no difference in the PROMs, MOCART scores, T21 mapping and dGEMRIC values between the groups. Use of cultured MSCs leads to good clinical outcomes similar to ACI and represents a promising treatment to restore the articular cartilage in the knee.     

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, resulting 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 PubMed, Scopus and Google Scholar using appropriate keywords, examining the current literature on the well-known tissue engineering methods for the treatment of knee osteoarthritis.     

Treatment of a Focal Articular Cartilage Defect of the Talus with Polymer-Based Autologous Chondrocyte Implantation: A 12-Year Follow-Up Period

Autologous chondrocyte implantation (ACI) is a first-line treatment option for large articular cartilage defects. Although well-established for cartilage defects in the knee, studies of the long-term outcomes of matrix-assisted ACI to treat cartilage defects in the ankle are rare. In the present report, we describe for the first time the long-term clinical and radiologic results 12 years after polymer-based matrix-assisted ACI treat a full-thickness talar cartilage defect in a 25-year-old male patient. The clinical outcome was assessed using the visual analog scale and Freiburg ankle score, magnetic resonance imaging evaluation using the Henderson-Kreuz scoring system and T2 mapping. Clinical assessment revealed improved visual analog scale and Freiburg ankle scores. The radiologic analysis and T2 relaxation time values indicated the formation of hyaline-like repair tissue. Polymer-based autologous chondrocytes has been shown to be a safe and clinically effective long-term treatment of articular cartilage defects in the talus.     

Editorial Commentary: Stem Cell Treatment in Knee Osteoarthritis: What for? Pain Management or Cartilage Regeneration?

The efficacy of mesenchymal stem cells regarding clinical outcomes and cartilage regeneration in knee osteoarthritis remains unclear; however, their theoretical role in multilineage cellular differentiation and immunomodulation of the arthritic cascade has been investigated. Several studies have reported that the use of stem cell therapy for knee osteoarthritis helps in pain improvement, but its effect on cartilage regeneration has not yet been explored. Moreover, numerous studies have reported high heterogeneity in the cell sources, as well as methods of culture expansion or cell concentration, and differences in delivery methods, assessment tools, and concomitant surgical procedures, which could affect the clinical outcomes or evaluation of cartilage regeneration potency. Furthermore, future studies are warranted to examine these factors in detail to interpret the results of mesenchymal stem cell treatment for knee osteoarthritis.     

A prospective,randomised comparison of autologous chondrocyte implantation versus mosaicplasty for osteochondral defects in the knee

Autologous chondrocyte implantation (ACI) and mosaicplasty are both claimed to be successful for the repair of defects of the articular cartilage of the knee but there has been no comparative study of the two methods. A total of 100 patients with a mean age of 31.3 years (16 to 49) and with a symptomatic lesion of the articular cartilage in the knee which was suitable for cartilage repair was randomised to undergo either ACI or mosaicplasty; 58 patients had ACI and 42 mosaicplasty. Most lesions were post-traumatic and the mean size of the defect was 4.66 cm2. The mean duration of symptoms was 7.2 years and the mean number of previous operations, excluding arthroscopy, was 1.5. The mean follow-up was 19 months (12 to 26). Functional assessment using the modified Cincinatti and Stanmore scores and objective clinical assessment showed that 88% had excellent or good results after ACI compared with 69% after mosaicplasty. Arthroscopy at one year demonstrated excellent or good repairs in 82% after ACI and in 34% after mosaicplasty. All five patellar mosaicplasties failed. Our prospective, randomised, clinical trial has shown significant superiority of ACI over mosaicplasty for the repair of articular defects in the knee. The results for ACI are comparable with those in other studies, but those for mosaicplasty suggest that its continued use is of dubious value.     

Induced pluripotent stem cells in cartilage repair

Articular cartilage repair techniques are challenging. Human embryonic stem cells and induced pluripotent stem cells(i PSCs) theoretically provide an unlimited number of specialized cells which could be used in articular cartilage repair. However thus far chondrocytes from iPSCs have been created primarily by viral transfection and with the use of cocultured feeder cells. In addition chondrocytes derived from i PSCs have usually been formed in condensed cell bodies(resembling embryoid bodies) that then require dissolution with consequent substantial loss of cell viability and phenotype. All of these current techniques used to derive chondrocytes from i PSCs are problematic but solutions to these problems are on the horizon. These solutions will make i PSCs a viable alternative for articular cartilage repair in the near future.     

Restoration of Injured or Degenerated Articular Cartilage

Intra-articular fractures, ligamentous and meniscal injuries, and articular cartilage breakdown are major causes of degenerative joint disease. Lesions on the articular surface seem to have a limited capacity for repair and often progress inexorably toward osteoarthritis. Recent studies on joint immobilization and cartilage atrophy, however, have shown that repair and remodeling of articular cartilage may be possible. Currently used clinical methods of stimulating cartilage repair and remodeling include alteration of the loading on degenerated joints (primarily by using osteotomies), introduction of new cartilage-forming cells by perforation of subchondral bone, and soft-tissue arthroplasty. These procedures provide temporary relief in selected patients, but they often do not predictably restore long-term joint function. Experimentally, cartilage repair has been stimulated successfully with the use of allografts of periosteum and perichondrium, which serve as sources of cells with chondrogenic potential; introduction of cells grown in culture (stem cells or chondrocytes); stimulation by fibrin clot formation; artificial collagen matrices combined with cell transplants; and chondrogenic growth factors. The long-term success of all these methods has not been explored thoroughly, even in animal studies. Nevertheless, some research results are sufficiently encouraging to suggest that repair of the degenerating articular cartilage may be possible in the future.     

Stimulation of ankle cartilage: other emerging technologies (cellular, electricomagnetic, etc.)

Advances in understanding age-related changes in articular cartilage, joint homeostasis, the natural healing process after cartilage injury, and improved standards for evaluation of a joint surface made the ultimate goal of cartilage repair a possibility. New strategies for enhancement of articular cartilages' limited healing potential and biologic regeneration include advances in tissue engineering and the use of electromagnetic fields. This article reviews developments in basic science and clinical research made with these emerging technologies concerning treatment of articular cartilage defects and treatment of osteoarthritis of the ankle.     

The use of mesenchymal stem cells for chondrogenesis

The application of autologous chondrocytes in cartilage repair procedures is associated with several disadvantages, including injury of healthy cartilage in a preceding surgery frequently resulting in formation of inferior fibrocartilage at defect sites. In order to improve the quality of regeneration, adult mesenchymal stem cells (MSC) are regarded as a promising alternative. The great challenge, when considering MSC for articular cartilage repair, is to generate cells with features of stable chondrocytes which are resistant to hypertrophy and terminal differentiation, as found in hyaline articular cartilage. Common in vitro protocols for chondrogenic differentiation of MSC successfully induce expression of multiple cartilage-specific molecules, including collagen type II and aggrecan, and result in a chondrocyte-like phenotype. However, in vitro chondrogenesis of MSC additionally promotes induction of fibrocartilage-like features such as expression of collagen type I, and hypertrophy, as demonstrated by up-regulation of collagen type X, MMP13 and ALP-activity. As a consequence, differentiated MSC pellets undergo mineralisation and vascularisation after ectopic transplantation in a process similar to endochondral ossification. This review discusses the complexity and entailed challenges when considering MSC from various sources for clinical application and the necessity to optimise chondrogenesis by repressing hypertrophy to obtain functional and suitable cells for cartilage repair.     

Embryonic stem cells form articular cartilage, not teratomas, in osteochondral defects of rat joints

Embryonic stem (ES) cells are considered to be a potential tool for repairing articular cartilage defects, but so far it has been impossible to cause these cells to differentiate into chondrocytes exclusively, either in vivo or in vitro. To explore a potential new cell source of cell transplantation for articular cartilage defects, we transplanted ES cells into articular cartilage defects in immunosuppressed rats. ES cells (AB2.2 or CCE cells) were transplanted into articular cartilage defects in the patellar groove of immunosuppressed rats treated with cyclosporine. The cells were histologically observed until 8 weeks after transplantation. To determine whether the repair tissue in the defect in the AB2.2-transplanted group was derived from the transplanted cells, the neomycin-resistant gene, which had been transfected into AB2.2 cells but does not exist in rat cells, was used for detection. The cells produced cartilage, resulting in repair of the defects from 4 weeks until 8 weeks after the transplantation without forming any teratomas. The neomycin-resistant gene was detected in every sample, demonstrating that the repair tissue in the AB2.2-transplanted group was derived from the transplanted AB2.2 cells. The environment of osteochondral defects is chondrogenic for ES cells. ES cells may thus be a potential tool for repairing articular cartilage defects.     

Cellular origin of neocartilage formed at wound edges of articular cartilage in a tissue culture experiment

OBJECTIVE: The regeneration capacity of cartilage in general is limited. Complete repair of partial thickness articular cartilage has only been reported in a fetal sheep model. However, in long-term culture studies of articular cartilage explants we have observed outgrowth of chondrocytes and neocartilage formation at wound edges. This illustrates that under optimal circumstances articular cartilage is capable to regenerate hyaline cartilage. Recent studies suggest the presence of mesenchymal stem cells in articular cartilage. In the present study we investigated the origin of chondrocyte outgrowth and neocartilage formation at wound edges from immature and mature articular bovine cartilage explants in vitro, in order to understand which cells are responsible for repair. DESIGN: Full-thickness explants from immature and mature animals were cultured for 4 weeks and superficial and deep zone cartilage explants of immature animals were separately cultured. RESULTS: Significant more outgrowth was observed from immature explants as compared to mature explants. At wound edges of immature explants, this outgrowth showed high cell-densities, rounded cells, the extracellular matrix contained proteoglycans and collagen types I and II. We found proliferation activity both in the superficial zone and deep zone chondrocytes in immature explants, using the Ki67 proliferation marker. In the experiment culturing immature superficial and deep zone cartilage explants separately, there was abundant new tissue formation originating from deep cartilage and almost no outgrowth from the superficial cartilage. This indicates that neocartilage originates from chondrocytes in the deep zone cartilage and not from chondrocytes in the superficial zone cartilage. CONCLUSIONS: Present data can help to understand wound healing in partial-thickness and full-thickness defects of immature and mature cartilage and can be of help in finding methods to stimulate the regeneration of articular cartilage.     

The role of mandibular condylar cartilage in articular cartilage repair.

The articular hyaline cartilage of synovial joints has a very limited capacity for repair after injury. In contrast, the mandibular condylar cartilage of the temporomandibular joint possesses as intrinsic potential for regeneration. This study aimed to test the hypothesis that cultured allografts of mandibular condylar cartilage could be used to promote biological repair of injured orthotopic joint surfaces. Using a primate animal model, cultures of mandibular condylar cartilage cells were grafted into surgically created defects in a recipient hyaline cartilage joint surface. Articular wound healing was assessed macroscopically and histologically over a postoperative period of 52 weeks. Mandibular condylar cartilage cells scheduled for allogenous transplantation were initially characterised in vitro. Expansion of primary colonies in organ culture provided the allogenic cellular material for in vivo grafting. Grafting of osteochondral articular wounds with 5-week cultures of mandibular cartilage cells led to wound regeneration with complete reconstitution of articular surface continuity by 52 weeks. There was novel synthesis of cartilage collagens and sulphated glycosaminoglycans within the repair tissue and no evidence of immunological rejection. Healing of grafted defects was thought to occur by a combination of donor cell proliferation and ingress of host mesenchymal cells. In contrast, grafted control wounds underwent largely fibrous repair with incomplete articular regeneration. In conclusion, transplanted allografts of cultured mandibular condylar cartilage appeared to have the ability, in this primate model, to promote cartilaginous repair and regeneration of orthotopic articular wounds.     

Skeletal tissue regeneration: where can hydrogels play a role?

The emerging field of tissue engineering reveals promising approaches for the repair and regeneration of skeletal tissues including the articular cartilage, bone, and the entire joint. Amongst the myriad of biomaterials available to support this strategy, hydrogels are highly tissue mimicking substitutes and thus of great potential for the regeneration of functional tissues. This review comprises an overview of the novel and most promising hydrogels for articular cartilage, osteochondral and bone defect repair. Chondro- and osteo-conductive and -instructive hydrogels are presented, highlighting successful combinations with inductive signals and cell sources. Moreover, advantages, drawbacks, and future perspectives of the role of hydrogels in skeletal regeneration are addressed, pointing out the current state of this rising approach.     

Treatment of full-thickness chondral defects in the knee with autologous chondrocyte implantation

Autologous chondrocyte implantation (ACI) has now been performed for over a decade in the United States. ACI has been demonstrated as a reproducible treatment option for large, full-thickness, symptomatic chondral injuries of the knee. As clinical experience has expanded and indications broadened to more complex cartilage defects, it has become evident that aggressive treatment of coexisting knee pathology is essential for optimal results. This includes management of malalignment, ligamentous, and/or meniscal deficiency, and subchondral bone loss to make the intra-articular environment as ideal as possible for successful cartilage restoration. Additionally, refinements in the rehabilitation necessary for biologic cartilage repair have been made, based on better understanding of the maturation process of the repair cartilage, allowing for earlier initiation of knee range of motion, strengthening exercises, and weight bearing. These changes have enhanced the recovery for the patient and decreased the risk of motion deficits. This article will discuss patient selection for ACI, review ACI surgical technique, including management of coexisting knee pathology, present postoperative ACI rehabilitation guidelines, and summarize clinical outcomes after ACI.     

Clinical relevance of scaffolds for cartilage engineering

The repair of articular cartilage defects in patients' knees presents a particular challenge to the orthopedic surgeon because cartilage lacks the ability to repair or regenerate itself. Various cartilage repair techniques have not produced a superior or uniform outcome, which has led to a new generation of cartilage repair based on tissue-engineering strategies and the use of biological scaffolds. Clinical advances have been made regarding the regeneration of articular cartilage, and continue to be made toward the achievement of a suitable treatment method for resurfacing osteochondral defects, through cartilage tissue engineering and the use of pluripotent cells seeded on bio-scaffolds.