A novel MSC‐seeded triphasic construct for the repair of osteochondral defects

Mesenchymal stem cells (MSC) are increasingly replacing chondrocytes in tissue engineering based research for treatment of osteochondral defects. The aim of this work was to determine whether repair of critical‐size chronic osteochondral defects in an ovine model using MSC‐seeded triphasic constructs would show results comparable to osteochondral autografting (OATS). Triphasic implants were engineered using a beta‐tricalcium phosphate osseous phase, an intermediate activated plasma phase, and a collagen I hydrogel chondral phase. Autologous MSCs were used to seed the implants, with chondrogenic predifferentiation of the cells used in the cartilage phase. Osteochondral defects of 4.0 mm diameter were created bilaterally in ovine knees (n = 10). Six weeks later, half of the lesions were treated with OATS and half with triphasic constructs. The knees were dissected at 6 or 12 months. With the chosen study design we were not able to demonstrate significant differences between the histological scores of both groups. Subcategory analysis of O'Driscoll scores showed superior cartilage bonding in the 6‐month triphasic group compared to the autograft group. The 12‐month autograft group showed superior cartilage matrix morphology compared to the 12‐month triphasic group. Macroscopic and biomechanical analysis showed no significant differences at 12 months. Autologous MSC‐seeded triphasic implants showed comparable repair quality to osteochondral autografts in terms of histology and biomechanical testing. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:1586–1599, 2010     

Tissue engineering‐based cartilage repair with mesenchymal stem cells in a porcine model

This in vivo pilot study explored the use of mesenchymal stem cell (MSC) containing tissue engineering constructs in repair of osteochondral defects. Osteochondral defects were created in the medial condyles of both knees of 16 miniature pigs. One joint received a cell/collagen tissue engineering construct with or without pretreatment with transforming growth factor β (TGF‐β) and the other joint from the same pig received no treatment or the gel scaffold only. Six months after surgery, in knees with no treatment, all defects showed contracted craters; in those treated with the gel scaffold alone, six showed a smooth gross surface, one a hypertrophic surface, and one a contracted crater; in those with undifferentiated MSCs, five defects had smooth, fully repaired surfaces or partially repaired surfaces, and one defect poor repair; in those with TGF‐β‐induced differentiated MSCs, seven defects had smooth, fully repaired surfaces or partially repaired surfaces, and three defects showed poor repair. In Pineda score grading, the group with undifferentiated MSC, but not the group with TGF‐β‐induced differentiated MSCs, had significantly lower subchondral, cell morphology, and total scores than the groups with no or gel‐only treatment. The compressive stiffness was larger in cartilage without surgical treatment than the treated area within each group. In conclusion, this preliminary pilot study suggests that using undifferentiated MSCs might be a better approach than using TGF‐β‐induced differentiated MSCs for in vivo tissue engineered treatment of osteochondral defects. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29:1874–1880, 2011     

脱细胞骨软骨支架复合自体骨髓间充质干细胞修复羊骨软骨缺损的研究

目的探讨脱细胞骨软骨支架接种自体骨髓间充质干细胞(BMSCs)修复羊骨软骨缺损效果,探索骨软骨缺损新的修复方式。方法制备直径为8mm骨软骨脱细胞支架,培养羊BMSCs,接种于骨软骨支架,制备羊负重区骨软骨缺损模型,分空白、空白支架及细胞支架复合物3组,每组4只羊,3个月后处死动物取标本行大体及组织学检测。结果修复羊负重区骨软骨缺损模型实验结果显示细胞支架复合修复组骨软骨有较好修复,空白支架组软骨下骨基本修复、软骨侧无明显修复,空白对照组未见明显修复,缺损边缘软骨退变。结论含骨软骨连接结构的脱细胞骨软骨支架接种种子细胞能较好的修复羊负重区骨软骨缺损。     

Tissue‐Engineered Tracheal Reconstruction Using Three‐Dimensionally Printed Artificial Tracheal Graft: Preliminary Report

Three‐dimensional printing has come into the spotlight in the realm of tissue engineering. We intended to evaluate the plausibility of 3D‐printed (3DP) scaffold coated with mesenchymal stem cells (MSCs) seeded in fibrin for the repair of partial tracheal defects. MSCs from rabbit bone marrow were expanded and cultured. A half‐pipe‐shaped 3DP polycaprolactone scaffold was coated with the MSCs seeded in fibrin. The half‐pipe tracheal graft was implanted on a 10 × 10‐mm artificial tracheal defect in four rabbits. Four and eight weeks after the operation, the reconstructed sites were evaluated bronchoscopically, radiologically, histologically, and functionally. None of the four rabbits showed any sign of respiratory distress. Endoscopic examination and computed tomography showed successful reconstruction of trachea without any collapse or blockage. The replaced tracheas were completely covered with regenerated respiratory mucosa. Histologic analysis showed that the implanted 3DP tracheal grafts were successfully integrated with the adjacent trachea without disruption or granulation tissue formation. Neo‐cartilage formation inside the implanted graft was sufficient to maintain the patency of the reconstructed trachea. Scanning electron microscope examination confirmed the regeneration of the cilia, and beating frequency of regenerated cilia was not different from those of the normal adjacent mucosa. The shape and function of reconstructed trachea using 3DP scaffold coated with MSCs seeded in fibrin were restored successfully without any graft rejection.     

组织工程骨软骨复合体修复犬膝关节负重区骨软骨缺损的实验研究

目的 观察以骨软骨支架复合骨髓基质干细胞(bone-fflarrow mesenchymal stem cells,BMSCs)修复犬膝关节负重区骨软骨缺损的疗效.方法 利用软骨细胞外基质作为软骨支架部分,以脱细胞骨作为骨支架部分,采用相分离技术制备骨软骨双相支架,将成软骨诱导的BMSCs种植到双相支架上构建组织工程骨软骨复合体,并以此复合体修复犬膝关节股骨髁负重区骨软骨缺损,分为细胞-双相支架组(实验组)和单纯支架组(对照组).分别在术后3和6个月时取材,根据大体、组织学、Micro-CT等检测结果进行半定量或定量评估.结果 大体及组织学评价表明:同一时间点实验组的修复效果优于对照组,且实验组在术后6个月时的修复效果优于其术后3个月时,两项差异均有统计学意义;而对照组小同时间点修复效果的差异无统计学意义.Micro-CT检测结果表明实验组与对照组软骨下骨均得到重建,两者的差异尤统计学意义.结论 骨软骨双相支架复合成软骨诱导的BMSCs能成功修复犬膝关节负重区的骨软骨缺损,其修复效果明显优于单纯支架植入组.     

Engineering und Charakterisierung von funktionalem osteochondralem Ersatzgewebe

Extensive osteochondral lesions require repair of the cartilage and underlying bone. We generated osteochondral repair tissue by tissue engineering. Standardized defects, 7 x 5 x 5 mm, were created in femoropatellar grooves of adult rabbits. Engineered cartilage, generated in vitro starting from chondrocytes and a biodegradable scaffold, was implanted using Collagraft as subchondral support. Cell-free implants, defects left empty, and unoperated knee joints served as controls. Explants were characterized morphologically and mechanically. Engineered cartilage implants were superior to cell-free implants and to natural healing of empty defects with respect to the histologic score and Young's modulus of the 6-month repair tissue. These data suggest that engineered cartilage can provide primary stability for the treatment of critical osteochondral defects.     

Orderly osteochondral regeneration in a sheep model using a novel nano‐composite multilayered biomaterial

The objective of this article was to investigate the safety and regenerative potential of a newly developed biomimetic scaffold when applied to osteochondral defects in an animal model. A new multilayer gradient nano‐composite scaffold was obtained by nucleating collagen fibrils with hydroxyapatite nanoparticles. In the femoral condyles of 12 sheep, 24 osteochondral lesions were created. Animals were randomized into three treatment groups: scaffold alone, scaffold colonized in vitro with autologous chondrocytes and empty defects. Six months after surgery, the animals were sacrificed and the lesions were histologically evaluated. Histologic and gross evaluation of specimens showed good integration of the chondral surface in all groups except for the control group. Significantly better bone regeneration was observed both in the group receiving the scaffold alone and in the group with scaffold loaded with autologous chondrocytes. No difference in cartilage surface reconstruction and osteochondral defect filling was noted between cell‐seeded and cell‐free groups. In the control group, no bone or cartilage defect healing occurred, and the defects were filled with fibrous tissue. Quantitative macroscopic and histological score evaluations confirmed the qualitative trends observed. The results of the present study showed that this novel osteochondral scaffold is safe and easy to use, and may represent a suitable matrix to direct and coordinate the process of bone and hyaline‐like cartilage regeneration. The comparable regeneration process observed with or without autologous chondrocytes suggests that the main mode of action of the scaffold is based on the recruitment of local cells. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:116–124, 2010     

Combination therapy with intra‐articular injection of mesenchymal stem cells and articulated joint distraction for repair of a chronic osteochondral defect in the rabbit

The present study investigated intra‐articular injection of bone‐marrow‐derived mesenchymal stem cells (MSCs) combined with articulated joint distraction as treatment for osteochondral defects. Large osteochondral defects were created in the weight‐bearing area of the medial femoral condyle in rabbit knees. Four weeks after defect creation, rabbits were divided into six groups: control group, MSC group, distraction group, distraction + MSC group, temporary distraction group, and temporary distraction + MSC group. Groups with MSC received intra‐articular injection of MSCs. Groups with distraction underwent articulated distraction arthroplasty. Groups with temporary distraction discontinued the distraction after 4 weeks. The rabbits were euthanized at 4, 8, and 12 weeks after treatment except temporary distraction groups which were euthanized at only 12 weeks. Histological scores in the distraction + MSC group were significantly better than in the control, MSC group or distraction group at 4 and 8 weeks, but showed no further improvement. At 12 weeks, the temporary distraction + MSC group showed the best results, demonstrating hyaline cartilage repair with regeneration of the osteochondral junction. In conclusion, joint distraction with intra‐articular injection of MSCs promotes early cartilage repair, and compressive loading of the repair tissue after temporary distraction stimulates articular cartilage regeneration. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1466–1473, 2015.     

Repair of large osteochondral defects in rabbits using porous hydroxyapatite/collagen (HAp/Col) and fibroblast growth factor‐2 (FGF‐2)

Articular cartilage has a limited capacity for self‐renewal. This article reports the development of a porous hydroxyapatite/collagen (HAp/Col) scaffold as a bone void filler and a vehicle for drug administration. The scaffold consists of HAp nanocrystals and type I atelocollagen. The purpose of this study was to investigate the efficacy of porous HAp/Col impregnated with FGF‐2 to repair large osteochondral defects in a rabbit model. Ninety‐six cylindrical osteochondral defects 5 mm in diameter and 5 mm in depth were created in the femoral trochlear groove of the right knee. Animals were assigned to one of four treatment groups: porous HAp/Col impregnated with 50 µl of FGF‐2 at a concentration of 10 or 100 µg/ml (FGF10 or FGF100 group); porous HAp/Col with 50 µl of PBS (HAp/Col group); and no implantation (defect group). The defect areas were examined grossly and histologically. Subchondral bone regeneration was quantified 3, 6, 12, and 24 weeks after surgery. Abundant bone formation was observed in the HAp/Col implanted groups as compared to the defect group. The FGF10 group displayed not only the most abundant bone regeneration but also the most satisfactory cartilage regeneration, with cartilage presenting a hyaline‐like appearance. These findings suggest that porous HAp/Col with FGF‐2 augments the cartilage repair process. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:677–686, 2010     

组织工程骨软骨复合物的构建与形态学观察

目的探讨采用组织工程技术构建骨软骨复合物的可行性。方法将骨髓基质细胞(BMSCs)成诱导软骨后接种于快速成形的三维支架材料聚乳酸／聚羟乙酸共聚物(PLGA)构建组织工程软骨，经成骨诱导的BMSCs接种于聚乳酸／聚羟乙酸共聚物／磷酸三钙(PLGA／TCP)构建组织工程骨，在体外分别培养2周后，将两种工程化组织及两者以无损伤线缝合形成的组织工程骨软复合体分别植入自体股部肌袋，术后8周取材，行组织学观察。结果术后组织学观察表明。组织工程软骨在体内可形成软骨组织组织工程骨在体内可形成骨组织，两者的复合体在体内可形成骨软骨复合物。结论以骨髓基质细胞为种子细胞、以快速成形的生物降解材料为支架体外构建的组织工程骨软骨复合物，可在体内形成骨软骨组织，有望用于骨软骨缺损的修复。     

Low‐dose BMP‐2 and MSC dual delivery onto coral scaffold for critical‐size bone defect regeneration in sheep

Tissue‐engineered constructs (TECs) combining resorbable calcium‐based scaffolds and mesenchymal stem cells (MSCs) have the capability to regenerate large bone defects. Inconsistent results have, however, been observed, with a lack of osteoinductivity as a possible cause of failure. This study aimed to evaluate the impact of the addition of low‐dose bone morphogenetic protein‐2 (BMP‐2) to MSC‐coral‐TECs on the healing of clinically relevant segmental bone defects in sheep. Coral granules were either seeded with autologous MSCs (bone marrow‐derived) or loaded with BMP‐2. A 25‐mm‐long metatarsal bone defect was created and stabilized with a plate in 18 sheep. Defects were filled with one of the following TECs: (i) BMP (n = 5); (ii) MSC (n = 7); or (iii) MSC‐BMP (n = 6). Radiographic follow‐up was performed until animal sacrifice at 4 months. Bone formation and scaffold resorption were assessed by micro‐CT and histological analysis. Bone union with nearly complete scaffold resorption was observed in 1/5, 2/7, and 3/6 animals, when BMP‐, MSC‐, and MSC‐BMP‐TECs were implanted, respectively. The amount of newly formed bone was not statistically different between groups: 1074 mm³ [970–2478 mm³], 1155 mm³ [970–2595 mm³], and 2343 mm³ [931–3276 mm³] for BMP‐, MSC‐, and MSC‐BMP‐TECs, respectively. Increased scaffold resorption rate using BMP‐TECs was the only potential side effect observed. In conclusion, although the dual delivery of MSCs and BMP‐2 onto a coral scaffold further increased bone formation and bone union when compared to single treatment, results were non‐significant. Only 50% of the defects healed, demonstrating the need for further refinement of this strategy before clinical use. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2637–2645, 2017.

     

Effect of tenascin‐C on the repair of full‐thickness osteochondral defects of articular cartilage in rabbits

The purpose of this study was to examine the effect of tenascin‐C (TNC) on the repair of full‐thickness osteochondral defects of articular cartilage in vivo. We used a gellan–gellan–sulfate sponge (Gellan–GS) to maintain a TNC‐rich environment in the cartilage defects. We implanted Gellan‐GS soaked in PBS only (Group 1), Gellan‐GS soaked in 10 µg/ml of TNC (Group 2), and Gellan‐GS soaked in 100 µg/ml of TNC (Group 3) into a full‐thickness osteochondral defect of the patellar groove of rabbits. The defect area was examined grossly and histologically 4–12 weeks after surgery. Sections of synovium were also immunohistochemically investigated. Histologically as well as macroscopically, the defects in Group 2 showed better repair than the other groups at 8 and 12 weeks after surgery. Inflammation of the synovium tended to diminish over time in all groups, and the degree of synovitis was the same for all three groups at each time point. In conclusion, Gellan–GS soaked in TNC can be used as a novel scaffold for the repair of articular cartilage defects. This study also indicates that TNC promotes the repair of full‐thickness osteochondral defects in vivo. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:563–571, 2015.     

Repair of superficial osteochondral defects with an autologous scaffold-free cartilage construct in a caprine model: implantation method and short-term results

OBJECTIVE: To compare four different implantation modalities for the repair of superficial osteochondral defects in a caprine model using autologous, scaffold-free, engineered cartilage constructs, and to describe the short-term outcome of successfully implanted constructs. METHODS: Scaffold-free, autologous cartilage constructs were implanted within superficial osteochondral defects created in the stifle joints of nine adult goats. The implants were distributed between four 6-mm-diameter superficial osteochondral defects created in the trochlea femoris and secured in the defect using a covering periosteal flap (PF) alone or in combination with adhesives (platelet-rich plasma (PRP) or fibrin), or using PRP alone. Eight weeks after implantation surgery, the animals were killed. The defect sites were excised and subjected to macroscopic and histopathologic analyses. RESULTS: At 8 weeks, implants that had been held in place exclusively with a PF were well integrated both laterally and basally. The repair tissue manifested an architecture similar to that of hyaline articular cartilage. However, most of the implants that had been glued in place in the absence of a PF were lost during the initial 4-week phase of restricted joint movement. The use of human fibrin glue (FG) led to massive cell infiltration of the subchondral bone. CONCLUSIONS: The implantation of autologous, scaffold-free, engineered cartilage constructs might best be performed beneath a PF without the use of tissue adhesives. Successfully implanted constructs showed hyaline-like characteristics in adult goats within 2 months. Long-term animal studies and pilot clinical trials are now needed to evaluate the efficacy of this treatment strategy.     

Sizable Scaffold‐Free Tissue‐Engineered Articular Cartilage Construct for Cartilage Defect Repair

This study introduces an implantable scaffold‐free cartilage tissue construct (SF) that is composed of chondrocytes and their self‐produced extracellular matrix (ECM). Chondrocytes were grown in vitro for up to 5 weeks and subjected to various assays at different time points (1, 7, 21, and 35 days). For in vivo implantation, full‐thickness defects (n = 5) were manually created on the trochlear groove of the both knees of rabbits (16‐week old) and 3 week‐cultured SF construct was implanted as an allograft for a month. The left knee defects were implanted with 1, 7, and 21 days in vitro cultured scaffold‐free engineered cartilages. (group 2, 3, and 4, respectively). The maturity of the engineered cartilages was evaluated by histological, chemical and mechanical assays. The repair of damaged cartilages was also evaluated by gross images and histological observations at 4, 8, and 12 weeks postsurgery. Although defect of groups 1, 2, and 3 were repaired with fibrocartilage tissues, group 4 (21 days) showed hyaline cartilage in the histological observation. In particular, mature matrix and columnar organization of chondrocytes and highly expressed type II collagen were observed only in 21 days in vitro cultured SF cartilage (group 4) at 12 weeks. As a conclusion, cartilage repair with maturation was recapitulated when implanted the 21 day in vitro cultured scaffold‐free engineered cartilage. When implanting tissue‐engineered cartilage, the maturity of the cartilage tissue along with the cultivation period can affect the cartilage repair.     

Failure of xenoimplantation using porcine synovium‐derived stem cell‐based cartilage tissue constructs for the repair of rabbit osteochondral defects

The use of xenogeneic tissues offers many advantages with respect to availability, quality control, and timing of tissue harvest. Our previous study indicated that implantation of premature tissue constructs from allogeneic synovium‐derived stem cells (SDSCs) facilitated cartilage tissue regeneration. The present study investigated the feasibility of xenoimplantation of SDSC‐based premature tissue constructs for the repair of osteochondral defects. Porcine SDSCs were mixed with fibrin gel, seeded in polyglycolic acid (PGA) scaffolds, and cultured in a rotating bioreactor system supplemented for 1 month with growth factor cocktails. The engineered porcine premature tissues were implanted to repair surgically induced osteochondral defects in the medial femoral condyles of 12 rabbits. Three weeks after surgery, the xenoimplantation group exhibited a smooth, whitish surface while the untreated control remained empty. Surprisingly, 6 months after surgery, the xenoimplantation group displayed some tissue loss while the untreated control group was overgrown with fibrocartilage tissue. In the xenoimplantation group, chronic inflammation was observed in synovial tissue where porcine major histocompatibility complex (MHC) class II antigen positively stained in the engulfed foreign bodies. In addition, porcine source cells also migrated from the implantation site and may have been responsible for the observed loss of glycosaminoglycans (GAGs) underneath surrounding articular cartilage. The histological score was much worse in the xenoimplanted group than in the untreated control. Our study suggested that SDSC‐based xenogeneic tissue constructs might cause delayed immune rejection. Xenotransplantation may not be an appropriate approach to repair osteochondral defects. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:1064–1070, 2010     

Oligo[poly(ethylene glycol)fumarate] Hydrogel Enhances Osteochondral Repair in Porcine Femoral Condyle Defects

Background

Management of osteochondritis dissecans remains a challenge. Use of oligo[poly(ethylene glycol)fumarate] (OPF) hydrogel scaffold alone has been reported in osteochondral defect repair in small animal models. However, preclinical evaluation of usage of this scaffold alone as a treatment strategy is limited.

Questions/purposes

We therefore (1) determined in vitro pore size and mechanical stiffness of freeze-dried and rehydrated freeze-dried OPF hydrogels, respectively; (2) assessed in vivo gross defect filling percentage and histologic findings in defects implanted with rehydrated freeze-dried hydrogels for 2 and 4 months in a porcine model; (3) analyzed highly magnified histologic sections for different types of cartilage repair tissues, subchondral bone, and scaffold; and (4) assessed neotissue filling percentage, cartilage phenotype, and Wakitani scores.

Methods

We measured pore size of freeze-dried OPF hydrogel scaffolds and mechanical stiffness of fresh and rehydrated forms. Twenty-four osteochondral defects from 12 eight-month-old micropigs were equally divided into scaffold and control (no scaffold) groups. Gross and histologic examination, one-way ANOVA, and one-way Mann-Whitney U test were performed at 2 and 4 months postoperatively.

Results

Pore sizes ranged from 20 to 433 μm in diameter. Rehydrated freeze-dried scaffolds had mechanical stiffness of 1 MPa. The scaffold itself increased percentage of neotissue filling at both 2 and 4 months to 58% and 54%, respectively, with hyaline cartilage making up 39% of neotissue at 4 months.

Conclusions

Rehydrated freeze-dried OPF hydrogel can enhance formation of hyaline-fibrocartilaginous mixed repair tissue of osteochondral defects in a porcine model.

Clinical Relevance

Rehydrated freeze-dried OPF hydrogel alone implanted into cartilage defects is insufficient to generate a homogeneously hyaline cartilage repair tissue, but its spacer effect can be enhanced by other tissue-regenerating mediators.     

自体骨髓间充质干细胞复合壳聚糖/羟基磷灰石支架修复兔膝骨软骨缺损

目的 探讨骨髓间充质干细胞(bone mesenehymal stem cells,BMSCs)复合壳聚糖(chitosan,CS)/羟基磷灰石(hydmxyapatite,HA)支架修复兔膝关节局部骨软骨缺损.方法 选健康日本大耳白兔36只,2～3月龄,体重1.7～2.0 kg,每只抽取自体骨髓4～6ml,体外分离培养BMSCs后以2×107/ml密度植于CS/HA支架上体外培养10 h,制成BMSCs-CS/HA支架复合物.将36只实验动物手术制成右膝股骨外侧髁负重区骨缺损模型后,随机分成A、B、C 3组,每组12只.A组植入BMSCs-CS/HA复合物,B组植入单纯CS/HA支架;C组不作任何植入,为空白对照组.分别于术后6周、12周各处死6只动物,取材后进行大体、组织学观察6根据改良Wakitani评分标准进行评分,评估软骨组织的修复情况,并行成组设计方差分析.结果 A组术后6周即可重建关节软骨缺损;修复软骨在观察期内逐渐变厚,软骨下骨有少量骨修复;术后12周透明软骨样修复,表面光整,与周围软骨色泽相近,软骨下骨有部分修复.而B组和C组12周时缺损区仍为纤维软骨样纤维组织修复,色泽浅黄.术后6、12周各组组织学半定量评分显示:股骨髁负重区修复A组评分明显优于B、C组(F=27.26,P＜0.05).结论 自体BMSCs复合CS/HA支架在体内环境下可形成透明软骨修复兔膝关节负重区骨软骨缺损.     

A novel nano-composite multi-layered biomaterial for treatment of osteochondral lesions: Technique note and an early stability pilot clinical trial

Introduction

Osteochondral articular defects are a key concern in orthopaedic surgery. Current surgical techniques to repair osteochondral defects lead to poor subchondral bone regeneration and fibrocartilage formation, which is often associated with joint pain and stiffness. The objective of this pilot clinical study is to evaluate the performance and the intrinsic stability of a newly developed biomimetic osteochondral scaffold and to test the safety and the feasibility of the surgical procedure.

Methods

A gradient composite osteochondral scaffold based on type I collagen-hydroxyapatite was obtained by nucleating collagen fibrils with hydroxyapatite nanoparticles.Thirteen patients (15 defect sites) were treated with scaffold implantation from January 2007 to July 2007: four at the medial femoral condyle, two at the lateral femoral condyles, five at the patellas and four at the trochleas. The mean size of the defects was 2.8 cm² (range: 1.5-5.9 cm²).All patients were followed up prospectively. High-resolution magnetic resonance imaging (MRI) was used to determine “the early postoperative adherence rate” at 4-5 weeks and 25-26 weeks after scaffold implantation. Moreover, the magnetic resonance observation of cartilage repair tissue (MOCART) ^{[13] and [14]} score was performed on every MRI. Two second-looks were performed at 6 months; cartilage repair was assessed using the International Cartilage Repair Society (ICRS) visual scoring system and histological and immunohistochemical analysis of the two biopsies was carried out.

Results

A completely attached graft and repair tissue were found in 13 of 15 lesions (86.7%). A partial detachment was observed in two patients (13.3%). No detached grafts were found.Complete filling of the cartilage defect and congruency of the articular surface were seen in 10 lesions (66.7%) with MRI evaluation at 6 months. The complete integration of the grafted cartilage was detected in eight lesions (53.3%). Subchondral bone changes (oedema or sclerosis) were found in eight defects (53.3%). Statistical analysis showed a significant improvement in the International Knee Documentation Committee (IKDC) subjective and objective scores from preoperative to 6 months’ follow-up (p < 0.0005).Visual scoring of the repaired tissue at second-look revealed a normal repair score in one case and a near-normal repair score in the other case. Histological analysis showed the formation of subchondral bone without the presence of biomaterial. The cartilage repair tissue appeared to be engaged in an ongoing maturation process.

Conclusions

The technique is safe and MRI evaluation at short-term follow-up has demonstrated good stability of the scaffold without any other fixation device. The preliminary clinical results at short-term follow-up are encouraging. A clinical and MRI study with longer follow-up and randomised studies will be done to confirm the high potential of this novel osteochondral scaffold.     

Cartilage repair by human umbilical cord blood‐derived mesenchymal stem cells with different hydrogels in a rat model

This study was carried out to assess the feasibility of human umbilical cord blood‐derived mesenchymal stem cells (hUCB‐MSCs) in articular cartilage repair and to further determine a suitable delivering hydrogel in a rat model. Critical sized full thickness cartilage defects were created. The hUCB‐MSCs and three different hydrogel composites (hydrogel A; 4% hyaluronic acid/30% pluronic (1:1, v/v), hydrogel B; 4% hyaluronic acid, and hydrogel C; 4% hyaluronic acid/30% pluronic/chitosan (1:1:2, v/v)) were implanted into the experimental knee (right knee) and hydrogels without hUCB‐MSCs were implanted into the control knee (left knee). Defects were evaluated after 8 weeks. The hUCB‐MSCs with hydrogels composites resulted in a better repair as seen by gross and histological evaluation compared with hydrogels without hUCB‐MSCs. Among the three different hydrogels, the 4% hyaluronic acid hydrogel composite (hydorgel B) showed the best result in cartilage repair as seen by the histological evaluation compared with the other hydrogel composites (hydrogel A and C). The results of this study suggest that hUCB‐MSCs may be a promising cell source in combination with 4% hyaluronic acid hydrogels in the in vivo repair of cartilage defects. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1580–1586, 2015.     

A preliminary study comparing the use of allogenic chondrogenic pre‐differentiated and undifferentiated mesenchymal stem cells for the repair of full thickness articular cartilage defects in rabbits

Chondrogenic differentiated mesenchymal stem cells (CMSCs) have been shown to produce superior chondrogenic expression markers in vitro. However, the use of these cells in vivo has not been fully explored. In this study, in vivo assessment of cartilage repair potential between allogenic‐derived chondrogenic pre‐differentiated mesenchymal stem cells and undifferentiated MSCs (MSCs) were compared. Bilateral full thickness cartilage defects were created on the medial femoral condyles of 12 rabbits (n = 12). Rabbits were divided into two groups. In one group, the defects in the right knees were repaired using alginate encapsulated MSCs while in the second group, CMSCs were used. The animals were sacrificed and the repaired and control knees were assessed at 3 and 6 months after implantation. Quantitative analysis was performed by measuring the Glycosaminoglycans (GAGs)/total protein content. The mean Brittberg score was higher in the transplanted knees as compared to the untreated knee at 6 months (p < 0.05). Quantitative analysis of GAGs was consistent with these results. Histological and immunohistochemical analysis demonstrated hyaline‐like cartilage regeneration in the transplanted sites. Significant differences between the histological scores based on O'Driscoll histological grading were observed between contralateral knees at both 3 and 6 months (p < 0.05). No significant differences were observed between the Britberg, O'Driscoll scores, and GAGs/total protein content when comparing defect sites treated with MSC and CMSC (p > 0.05). This study demonstrates that the use of either MSC or CMSC produced superior healing when compared to cartilage defects that were untreated. However, both cells produced comparable treatment outcomes. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29: 1336–1342, 2011