Systematic evaluation of the incidence of the knee donor area after autobone cartilage mosaic xentoplasty / 中国骨伤

OBJECTIVE@#To provide an overview of the incidence of knee donor -site morbidity after autologous osteochondral mosaicplasty.@*METHODS@#A comprehensive search was conducted in PubMed, EMbase, Wanfang Medical Network, and CNKI databases from January 2010 to April 20, 2021. Relevant literature was selected based on predefined inclusion and exclusion criteria, and data were evaluated and extracted. The correlation between the number and size of transplanted osteochondral columns and donor-site morbidity was analyzed.@*RESULTS@#A total of 13 literatures were included, comprising a total of 661 patients. Statistical analysis revealed an incidence of knee donor-site morbidity at 8.6% (57/661), with knee pain being the most common complaint, accounting for 4.2%(28/661). There was no significant correlation between the number of osteochondral columns and postoperative donor-site incidence (P=0.424, N=10), nor between the diameter size of osteochondral columns and postoperative donor-site incidence(P=0.699, N=7).@*CONCLUSION@#Autologous osteochondral mosaicplasty is associated with a considerable incidence of knee donor-site morbidity, with knee pain being the most frequent complaint. There is no apparent correlation between donor-site incidence and the number and size of transplanted osteochondral columns. Donors should be informed about the potential risks.

Biocompatibility of tissue engineered cartilage constructedin vivoby silk fibroin-chitosan scaffold carrying bone marrow mesenchymal stem cells / 中国组织工程研究

BACKGROUND: Our previous studies have found that silk fibroin-chitosan scaffold carrying bone marrow mesenchymal stem cells can repair cartilage defect in rabbits, but further exploration on the biocompatibility of tissue engineered cartilage is yet to be done. OBJECTIVE: To explore the biocompatibility of tissue engineered cartilage that is constructed in vitro by silk fibroin-chitosan scaffold with bone marrow mesenchymal stem cells. METHODS: Three-dimensional silk fibroin-chitosan scaffolds were prepared in a ratio of 1:1. Rabbit bone marrow mesenchymal stem cells were extracted, induced and seeded onto the silk fibroin-chitosan scaffold to construct the cell-scaffold composite. The composite was then implanted into a rabbit joint defect model for cartilage repair. There were three groups in the present study: Experiment group with implantation of induced bone marrow mesenchymal stem cells+silk fibroin-chitosan scaffold into the cartilage defect model, control group with implantation of silk fibroin-chitosan scaffold into the cartilage defect model, and blank group without implantation. RESULTS AND CONCLUSION: The three-dimensional silk fibroin-chitosan scaffolds were successfully prepared and combined with bone marrow mesenchymal stem cells (BMSCs) to construct the tissue engineered cartilage for repair cartilage defects in rabbits. Blood routine parameters, procalcitonin levels, erythrocyte sedimentation rates and C-reactive protein levels detected at 2, 4, 8, and 12 weeks post-implantation indicated no obvious signs of systemic infection, and there was no damage to liver and kidney functions in the three groups. There were also no significant differences between the three groups in terms of blood routines and liver and kidney functions (P > 0.05). As shown by gross observation, hematoxylin-eosin staining and scanning electron microscope, in the experimental group, cartilage defects were repaired, with scaffold degradation, no presence of inflammatory cells, and good integration with surrounding tissues. Therefore, tissue engineered cartilage constructed in vitro by silk fibroin-chitosan scaffolds carrying bone marrow mesenchymal stem cells has good biocompatibility, which provides an experimental basis for tissue engineering approaches to cartilage repair.

Tissue engineering methods for repair of articular cartilage defect under special conditions / 中国组织工程研究

BACKGROUND: Although desired cartilage repair has been realized via tissue engineering technology, these achievements mainly focus on small-size defect under a normal physical condition. However, cartilage defects are always accompanied by the underlying diseases in clinical practice, such as osteoarthritis and rheumatoid arthritis. Meanwhile, the location, scope, and depth of cartilage defects are uncertain, which brings a great challenge in cartilage tissue repair. OBJECTIVE: To summarize the methods of repairing articular cartilage defects at different locations and under inflammatory condition. METHODS: We searched PubMed and CNKI with the search terms “cartilage defect regeneration, osteochondral, growth plate, weight-bearing area, inflammatory” in Chiense and English to retrieve related papers published before March 2019. A total of 209 papers were retrieved and 86 were included in the final analysis according to inclusion and exclusion criteria. RESULTS AND CONCLUSION: For articular cartilage defects under different special conditions, the repair goals and strategies are different. For repair of full-layer cartilage defects and osteochondral structure defects, multi-layered scaffolds are often used to repair the unique stratified cartilage structure and subchondral bone structure, while avoiding the problem of heterotopic ossification in neonatal cartilage. To avoid deformity after long bone maturation, growth factors such as insulin-like growth factor and bone morphogenetic protein 7 should be added to continuously stimulate the repair of the growth plate and promote bone growth. For cartilage repair in the weight-bearing area, the scaffolds should have good mechanical property, which ensure not to undergo severe deformation and structural damage when loaded. In addition, the new cartilage tissue has sufficient mechanical strength to support sustained longitudinal pressure and wear. For cartilage defects in the inflammatory state, both inflammation management and cartilage defect repair should be considered, and introduction of mesenchymal stem cells can regulate immune function and promote tissue regeneration, such that articular cartilage defect can be completely repaired.

Differences in the effect of two injectable Pluronic F-127 hydrogel composites in repairing rabbit cartilage defects / 中国组织工程研究

BACKGROUND: Preliminary experiments show that bone marrow mesenchymal stem cells transfected with SOX9 gene can grow and proliferate in Pluronic F-127 hydrogel, promote the secretion of extracellular matrix, and increase the expression of cartilage matrix. OBJECTIVE: The SOX9 gene was transduced into bone marrow mesenchymal stem cells by lentivirus gene induction, and then combined with injectable Pluronic F-127 hydrogel to observe the effect of Pluronic F-127 hydrogel on repairing cartilage defects. METHODS: SOX9 gene was transfected into bone marrow mesenchymal stem cells by lentivirus gene induction. After 48 hours of transfectlon, SOX9 gene was combined with Pluronic F-127 hydrogel. Sixty New Zealand white rabbits provided by the Experimental Animal Center of Wuhan University of Science and Technology were selected to establish the models of femoral condylar cartilage defect of the right knee joint. The rabbits were randomly divided into three groups: model group without implantation of any material at the defect site, control group with implantation of non-transfected bone marrow mesenchymal stem cells and Pluronic F-127 hydrogel complex at the defect site, and experimental group with implantation of SOX9 gene-transfected bone marrow mesenchymal stem cells and Pluronic F-127 hydrogel complex at the defect site. Four and twelve weeks after operation, the defect tissues were taken for three-dimensional reconstruction of micro-CT, hematoxylin-eosin staining, Safranine O staining, type II collagen immunohistochemical staining and Wakitani soft tissue repair histological score. This study was approved by the Ethics Committee of Wuhan University of Science and Technology. RESULTS AND CONCLUSION: (1) At 12 weeks after operation, three-dimensional reconstruction of Micro-CT showed that there was no obvious repair In the defect area of the model group, and there was still a large depression In the center. In the control group, the central depression area was significantly reduced and more trabecular structures of regenerated bone were observed. In the experimental group, the defect area was basically repaired. (2) At 12 weeks after operation, hematoxylin-eosin staining showed that there was no trabecular bone structure, disordered cell distribution and no cartilage lacunae at the defect area of the model group. In the control group, more bone tissue was reconstructed, and the defect area was mainly filled with cartilage-like tissue and fibrous tissue. In the experimental group, bone tissue was reconstructed adequately, and the defect area was mainly filled with chondroid cells and chondroid extracellular matrix. Cells arranged columnariy, similar to the surrounding cartilage. (3) At 12 weeks after surgery, Safranine O staining and collagen II immunohistochemical staining results showed that a small amount of glycosamlnoglycan was observed, but no type II collagen was found in the model group. The expression of glycosaminoglycan and type II collagen was more in the control group. The expression of glycosaminoglycan and type II collagen was highest In the experimental group compared with the other two groups. (4) The histological score of Wakitani soft tissue repair in the experimental group was higher than that in the control group and model group (P < 0.05). (5) The results suggested that Pluronic F-127 hydrogel complex loaded with SOX9 gene transfected bone marrow mesenchymal stem cells can promote the repair of cartilage defects.

Advances in research of mesenchymal stem cells in the treatment of osteoarthritis / 医学研究生学报

Osteoarthritis is a chronic progressive disease characterized by cartilage degenerative diseases. Due to the lack of vascular supply of articular cartilage and poor regeneration of chondrocytes, it is difficult to repair the cartilage with degenerative wear. A large number of studies have confirmed that bone marrow mesenchymal stem cells, adipose-derived mesenchymal stem cells, umbilical cord blood mesenchymal stem cells, umbilical cord mesenchymal stem cells, synovial mesenchymal stem cells, osteoarthritis joint fluid-derived mesenchymal stem cells, etc. can be effective to relieve osteoarthritis and repair damaged cartilage. Mesenchymal stem cells can directly differentiate into chondrocytes under appropriate microenvironment, and they also have immunosuppressive, anti-inflammatory and paracrine effects. In this paper, the research progress of basic experiments and clinical application of mesenchymal stem cells from different sources in osteoarthritis is reviewed to better promote the research progress of stem cell therapy for osteoarthritis.

Study on Repairing Effect of Kangfuxin Liquid on Cartilage Defect of Knee Osteoarthritis Model Rabbits and Its Mechanisms / 中国药房

OBJECTIVE： To investigate the effects of Kangfuxin liquid on repairing cartilage defect model of knee osteoarthritis （KOA） in rabbits and its mechanism. METHODS： Totally 72 male New Zealand rabbits were selected and randomly divided into model control group and Kangfuxin low-dose， medium-dose， high-dose groups， with 18 rabbits in each group. A cartilage defect model of the medial femoral condyle of the right knee joint in rabbits was established by drilling after anesthesia surgery. Then the rabbits in each group were given medicine via articular cavity immediately. Kangfuxin low-dose， middle-dose and high-dose groups were given 20％， 40％， 80％ Kangfuxin liquid； model control group was given constant volume of normal saline consecutively， 0.2 mL/kg， once every 3 days. At 4th， 8th， 12th week after medication， the wound repair of cartilage defect in rabbits was observed. Immediately after medication and at 4th， 8th， 12th week after medication， repaired tissue of cartilage defect in rabbits was scored histologically with Wakitani scoring standard under light microscope. At 12th week after medication， pathological changes of repaired tissue of cartilage defect in rabbits were observed by Masson staining. The levels of NO， SOD and LPO in joint fluid and PYD in urine of rabbits were detected by ELISA. RESULTS： At 4th， 8th， 12th week after medication， compared with model control group， cartilage defects in rabbits were repaired well in Kangfuxin low-dose， medium-dose and high-dose groups. At 4th， 8th， 12th week after medication， compared with immediately after medication and model control group at same time point， histomorphological score of repairing cartilage defect of knee joint in rabbits decreased significantly in Kangfuxin low-dose， medium-dose and high-dose groups （P＜0.05）. At 12th week after medication， compared with model control group， the histopathology degree of cartilage defect of knee joint in rabbits was significantly alleviated in Kangfuxin low-dose， medium-dose and high-dose groups. At 4th， 8th， 12th week after medication， compared with model control group， the levels of NO and LPO in joint fluid and PYD level in urine were decreased to different extent in Kangfuxin low-dose， medium-dose and high-dose groups， while SOD level was increased to different extent； at 12th week after medication， the difference of each index has statistical significance （P＜0.05 or P＜0.01）. CONCLUSIONS： Kangangxin liquid can significantly repair cartilage defect of KOA cartilage defect model rabbits， the mechanism of which may be associated with increasing the expression of SOD and mediating NO-inhibited chondrocyte apoptosis.

Promotion effect of cartilage regenerated scaffolds combined with exosomes derived from mutant type of HIF-1α modified BMSCs in repairing advanced cartilage defects / 吉林大学学报(医学版)

Objective:To explore the protective effect of exosomes secreted from bone mesenchymal stem cells (BMSCs)modified by hypoxia inducible factor-1α(HIF-1α)on the chondrocytes,and to elucidate the possible mechanism of its combination with cartilage regenerated scaffolds in promoting the repair of advanced cartilage defects.Methods:The exosomes(BMSCs-ExoWTand BMSCs-ExoMU)were extracted from the BMSCs modified by wild type of HIF-1α and mutant type of HIF-1α by ultracentrifugation method and identified in the meantime.In vitro the inflammatory response of chondrocytes were induced by interleukin-1β(IL-1β),the same amount of PBS, BMSCs-ExoWT(80 μg · mL-1),BMSCs-ExoMU(80 μg · mL-1)were respectively cultivated with the chondrocytes under the inflammatory reaction and blank group,inflammation group,BMSCs-ExoWTgroup and BMSCs-ExoMUgroup were set up;Hoechst33342 staining was used to detect the number of apoptotic bodies of chondrocytes in various groups.The Western blotting method was used to detect the expression levels of AKT/p-AKT,ERK/p-ERK and p38/p-p38 in the chondrocytes in various groups.Twelve New Zealand white rabbits were randomly divided into 4 groups and the models of rabbit knee cartilage defects were consructed;the equal volume of physiological saline,scaffold +physiological saline,scaffold +BMSCs-ExoWTand scaffold +BMSCs-ExoMUwere respectively injected into the cartilage defects of rabbits.Six weeks after operation,gross conference, HE and safranin O staining were used to observe and compare the repair effects of cartilage defects in each group. Results:BMSCs-ExoWTand BMSCs-ExoMUwere successfully extracted and identified,and the exosomes were observed to be nearly circular with diameter of about 40-100 nm;the Western blotting results showed that they expressed special proteins CD63 and CD81,respectively.In vitro,the number of apoptotic bodies of chondrocytes in BMSCs-ExoMUgroup was lower than those in inflammation group and BMSCs-ExoWTgroup(P<0.01).The Western blotting results revealed that the expression levels of p-ERK1/2 in BMSCs-ExoMUand BMSCs-ExoWT groups were lower than that in inflammation group(P<0.05);the expression levels of p-AKT and p-p38 were higher(P<0.05);the effect in BMSCs-ExoMUgroup was stronger than BMSCs-ExoWTgroup,and the difference was statistically significant(P<0.05).In the advanced cartilage defect models of rabbit knee joint,the repair effect in scaffold+ BMSCs-ExoMUgroup was better than those in blank group,scaffold group and scaffold+BMSCs-ExoWTgroup.Conclusion:Cartilage scaffold combined with BMSCs-ExoMUcan promote the repair of cartilage defects.

Research progress of rehabilitation after autologous chondrocyte implantation on knee / 中国修复重建外科杂志

Objective: To summarize the research progress of rehabilitation after autologous chondrocyte implantation (ACI). Methods: The literature related to basic science and clinical practice about rehabilitation after ACI in recent years was searched, selected, and analyzed. Results: Based on the included literature, the progress of the graft maturation consists of proliferation phase (0-6 weeks), transition phase (6-12 weeks), remodeling phase (12-26 weeks), and maturation phase (26 weeks-2 years). To achieve early protection, stimulate the maturation, and promote the graft-bone integrity, rehabilitation protocol ought to be based on the biomechanical properties at different phases. Weight-bearing program, range of motion (ROM), and options or facilities of exercise are importance when considering a rehabilitation program. Conclusion: It has been proved that the patients need a program with an increasingly progressive weight-bearing and ROM in principles of rehabilitation after ACI. Specific facilities can be taken at a certain phase. Evidences extracted in the present work are rather low and the high-quality and controlled trials still need to improve the rehabilitation protocol.

Promotion effect of cartilage regenerated scaffolds combined with exosomes derived from mutant type of HIF-1α modified BMSCs in repairing advanced cartilage defects / 吉林大学学报(医学版)

Objective: To explore the protective effect of exosomes secreted from bone mesenchymal stem cells (BMSCs) modified by hypoxia inducible factor-1α (HIF-1α) on the chondrocytes, and to elucidate the possible mechanism of its combination with cartilage regenerated scaffolds in promoting the repair of advanced cartilage defects. Methods: The exosomes (BMSCs-ExoWT and BMSCs-ExoMU) were extracted from the BMSCs modified by wild type of HIF-1α and mutant type of HIF-1α by ultracentrifugation method and identified in the meantime. In vitro the inflammatory response of chondrocytes were induced by interleukin-1β (IL-1β), the same amount of PBS, BMSCs-ExoWT (80 μg · ml-1), BMSCs-ExoMU (80 μg · m-1) were respectively cultivated with the chondrocytes under the inflammatory reaction and blank group, inflammation group, BMSCs-ExoWT group and BMSCs-ExoMU group were set up; Hoechst33342 staining was used to detect the number of apoptotic bodies of chondrocytes in various groups. The Western blotting method was used to detect the expression levels of AKT/p-AKT, ERK/p-ERK and p38/p-p38 in the chondrocytes in various groups. Twelve New Zealand white rabbits were randomly divided into 4 groups and the models of rabbit knee cartilage defects were consructed; the equal volume of physiological saline, scaffold + physiological saline, scaffold + BMSCs-ExoWT and scaffold + BMSCs-ExoMU were respectively injected into the cartilage defects of rabbits. Six weeks after operation, gross conference, HE and safranin O staining were used to observe and compare the repair effects of cartilage defects in each group. Results: BMSCs-ExoWT and BMSCs-ExoMU were successfully extracted and identified, and the exosomes were observed to be nearly circular with diameter of about 40-100 nm; the Western blotting results showed that they expressed special proteins CD63 and CD81, respectively. Invitro, the number of apoptotic bodies of chondrocytes in BMSCs-ExoMU group was lower than those in inflammation group and BMSCs-ExoWT group (P<0.01). The Western blotting results revealed that the expression levels of p-ERK1/2 in BMSCs-ExoMU and BMSCs-ExoWT groups were lower than that in inflammation group (P<0.05); the expression levels of p-AKT and p-p38 were higher (P<0.05); the effect in BMSCs-ExoMU group was stronger than BMSCs-ExoWT group, and the difference was statistically significant (P<0.05). In the advanced cartilage defect models of rabbit knee joint, the repair effect in scaffold + BMSCs-ExoMU group was better than those in blank group, scaffold group and scaffold + BMSCs-ExoWT group. Conclusion: Cartilage scaffold combined with BMSCs-ExoMU can promote the repair of cartilage defects.

Experimental Study on Effect of Drynaria Combining with Tissue Engineered Cartilage to Promote Cartilage Regeneration / 现代生物医学进展

Objective:To evaluate the effect of rhizome drynaria combined with tissue engineering cartilage on cartilage regeneration in experimental rabbits with cartilage defects.Methods:The hIGF-1 gene was transfected into MSCs by using the method of isola tion,purification and recombination of transgenic stem cells.The MSCs were transplanted into rabbit bone marrow mesenchymal stem cells (MSCs) in vitro.The cells were further amplified and mixed with acellular dermal matrix (ADM) to construct tissue engineered cartilage.Twenty-four New Zealand white rabbits,aged 6 months,were randomly divided into 4 groups (A,B,C and D).six rabbits in each group.Group A and C were transplanted with autologous cartilage.Group B and D were transplanted with modified cells.Group C and D group were fed with 40％ Drynaria Decoction,150ml/d for 4 weeks.Animals were sacrificed at 12 weeks postoperatively,and articular cartilage defects were isolated.Cartilage defect samples were embedded in paraffin blocks and stained with hematoxylin and eosin (H&E).Cartilage regeneration was evaluated by gross morphology,including sclerotic shape,color,contour and homogeneity.The quality of regenerated cartilage was assessed by histological scoring.Toluidine blue staining was used to evaluate the occurrence of chondrogenic glycosaminoglycans (GAG).Results:Compared with group B,the cartilage coverage,the color of new bone marrow,the edge of defect and the surface roughness of group C and D were significantly improved (P＜0.05);the cartilage surface score of regenerated cartilage was significantly improved P＜0.05).Groups C and D had better matrix,cell distribution and surface index than the other groups.And had a thick like hyaline cartilage tissue,with the normal glycosaminoglycan production.It is indicated that drynaria combined with tissue engineering cartilage can reduce cartilage defects by regenerating hyaline cartilage.Conclusion:Cartilage combined with drynariae can significantly improve the quality of cartilage defect repair in rabbit knee joint,and provide an important theoretical basis for clinical treatment of cartilage lesions.

Repair of Partial Thickness Cartilage Defects Using Cartilage Extracellular Matrix Membrane-Based Chondrocyte Delivery System in Human Ex Vivo Model

Treatment options for partial thickness cartilage defects are limited. The purpose of this study was to evaluate the efficacy of the chondrocyte-seeded cartilage extracellular matrix membrane in repairing partial thickness cartilage defects. First, the potential of the membrane as an effective cell carrier was investigated. Secondly, we have applied the chondrocyte-seeded membrane in an ex vivo, partial thickness defect model to analyze its repair potential. After culture of chondrocytes on the membrane in vitro, cell viability assay, cell seeding yield calculation and cell transfer assay were done. Cell carrying ability of the membrane was also tested by seeding different densities of cells. Partial defects were created on human cartilage tissue explants. Cell-seeded membranes were applied using a modified autologous chondrocyte implantation technique on the defects and implanted subcutaneously in nude mice for 2 and 4 weeks. In vitro data showed cell viability and seeding yield comparable to standard culture dishes. Time dependent cell transfer from the membrane was observed. Membranes supported various densities of cells. Ex vivo data showed hyaline-like cartilage tissue repair, integrated on the defect by 4 weeks. Overall, chondrocyte-seeded cartilage extracellular membranes may be an effective and feasible treatment strategy for the repair of partial thickness cartilage defects.

Influence of Recombinant Human Bone Morphogenetic Protein-2 on the Remodeling of Subchondral Bone and Cartilage Healing in the Articular Cartilage Defect of the Rabbit / 대한정형외과학회잡지

PURPOSE: The purpose of this study is to evaluate the effects of recombinant human bone morphogenetic protein-2 (rhBMP-2) after microfracture on the remodeling of subchondral bone and cartilage healing in a model of full-thickness articular cartilage injury in a rabbit. MATERIALS AND METHODS: A full thickness articular cartilage defect of 6x3-mm-size was created in the trochlear groove of the right femur in 24 rabbits. The defect was left empty in six rabbits, and microfracture was done in 18 rabbits. After microfracture, no treatment was done in six rabbits, defect was filled with fibrin glue in six rabbits, and with fibrin glue and rhBMP-2 in six rabbits. The effect of rhBMP-2 after microfracture was evaluated based on histological analysis and real-time polymerase chain reaction (PCR) for analysis of collagen type at 8 weeks after surgery. RESULTS: The score of histological grade scale of six rabbits in which the defect was filled with fibrin glue and rhBMP-2 was better than that of others and real-time PCR also showed a higher amount of collage type 1 and collage type 2 in these six rabbits. CONCLUSION: We consider that fibrin glue and rhBMP-2 after microfracture may accelerate cartilage healing in an articular cartilage defect and maybe helpful in healing the articular cartilage defect into more closely native hyaline cartilage.

Autologous chondrocyte implantation for knee focal cartilage defects: 3 years' follow-up at the University Malaya Medical Centre

Autologous chondrocyte implantation (ACI) is a widely accepted procedure for the treatment of large, fullthickness chondral defects involving various joints, but its use in developing countries is limited because of high cost and failure rates due to limited resources and support systems. Five patients (age <45 years) with focal cartilage defects received ACI at University of Malaya from 2006 to 2007 and followed up for 36 months. The average presubjective Knee Evaluation Forms (IKDC) improved from 38.44±6.29 to 25.6±8.04 postoperatively, the Oxford Knee Score (OKS) went from 25.6±8.04 to 13.96±1.63 and the American Knee Society Score (AKSS) improved from 80±14.33 to 92.96±5.82 post-operatively. Thus improvements were seen in the IKDC and AKSS score but not in the OKS. Magnetic resonance images showed the presence of cartilage tissue filling in the lateral and medial patellar facet and medial femoral condyle in three patients. Failures were seen in two patients, both with patellar defects and over the age of 36 years. Treatment with autologous chondrocyte implantation for focal cartilage defect in lateral and medial patellar facet and medial femoral condyle showed early improvement which was maintained at 3 yrs follow-up. ACI provided satisfactory outcome in focal cartilage defects involving the femoral condyle.

Mechanical properties ofinstantly repaired articular cartilage defects by tissue engineering / 医用生物力学

Objective To investigate the mechanical properties of both artificial cartilage and host cartilage by establishing the in vitro model of tissue engineered cartilage for repairing defects. Methods The agarose gel as an artificial cartilage was implanted in a deep cartilage defect connected with biological adhesive to set up the in vitro model of tissue engineered articular cartilage defects. Under the compression load, the instant mechanical behavior of the repair area was studied using the digital image correlation technology. Results There was no cracking phenomenon occurred at the interface during the compression process. The Strain distributions at middle layer of the repair area were obtained when the cartilage thickness appeared changes with 3.5%, 5.6%, 7.04% and 9.0% by the compression, respectively. When the compressing change increased from 3.5% to 9%, the maximum compressive strain of host cartilage was increased by 75.9%, and the maximum tensile strain of artificial cartilage was increased by 226.99% in the vertical direction of cartilage surface. In the direction parallel with cartilage surface, the maximum tensile strain at the interface was increased by 116.9%, and the increment was far more than that at the host cartilage area and artificial cartilage area. For shear strain at the repair area, the direction of shear strain at the interface changed oppositely with the compression increasing. Conclusions The repair effect of tissue engineered cartilage was uncertain due to the mechanical environment of the repair area. After the tissue engineered cartilage was implanted in the defect, the repair area was under the influence of complex strain states. The strains changed greatly at the interface both with the host cartilage and artificial cartilage as the compression increasing. The strain in the vertical direction of cartilage surface at the interface might change from compressive stain to tensile strain, which was significantly increased in the direction parallel with cartilage surface. The strain direction at the interface could even be changed oppositely, and the shear strain appeared rapidly increase. The complex strain states lead to such great changes in mechanical environment of the defect area, and may cause cracking at the interface, and even further affect the repair process. Therefore, attention should be given to this complex mechanical environment during cartilage defect repair process in clinical treatment.

Experiment study of rabbit joint articular cartilage defects repaired by thermosensitive CS/PVA composite hydrogel engineered hTGF-β1 transfected bone marrow mesenchymal stem cells / 中华显微外科杂志

Objective To investigate the experiment effects of rabbit joint articular cartilage defects repaired by thermosensitive CS/PVA composite hydrogel engineered hTGF-β1 transfected bone marrow mesenchymal stem cells. Methods Bone marrow mesenchymal stem cells were isolated and cultured in vitro. The positive rate of transfection was defected by cell immunohistochemistry methods after Ad-hTGF-β1 transfected for 1 week. Twenty-four adult New Zealand white rabbits with full articular cartilage defects were randomly divided into 4 groups, each group had 6 animals, both hind limbs were used in the experiment. Group A: hydrogel combined with transfected cells; Group B: hydrogel combined with untransfected cells; Group C: hydrogel group; Group D: blank control group. Specimens and histological observation were used to evaluate the repair effect after 16 weeks according to Pineda's score. Results The positive rate of hTGF-β1 expression in BMSCs was about 85.4% after transfection. After 16 weeks the defects of group A were repaired by cartilage-like tissue, the cell arrangement and densities of regenerated cartilage were similar to normal cartilage, type Ⅱ collagen immunohistochemistry were positive. There was a significant difference in Pineda's score compaired with other groups (P ＜ 0.05). Conclusion Rabbit articiular cartilage defects could be repaired by CS/PVA hydrogel engineered hTGF-β1-transfected bone marrow mesenchymal stem cells.

In Vitro Targeted Magnetic Delivery and Tracking of Superparamagnetic Iron Oxide Particles Labeled Stem Cells for Articular Cartilage Defect Repair / 华中科技大学学报（医学）（英德文版）

To assess a novel cell manipulation technique of tissue engineering with respect to its ability to augment superparamagnetic iron oxide particles (SPIO) labeled mesenchymal stem cells (MSCs) density at a localized cartilage defect site in an in vitro phantom by applying magnetic force.Meanwhile,non-invasive imaging techniques were use to track SPIO-labeled MSCs by magnetic resonance imaging (MRI).Human bone marrow MSCs were cultured and labeled with SPIO.Fresh degenerated human osteochondral fragments were obtained during total knee arthroplasty and a cartilage defect was created at the center.Then,the osteochondral fragments were attached to the sidewalls of culture flasks filled with phosphate-buffered saline (PBS) to mimic the human joint cavity.The SPIO-labeled MSCs were injected into the culture flasks in the presence of a 0.57 Tesla (T) magnetic force.Before and 90 min after cell targeting,the specimens underwent T2-weighted turbo spin-echo (SET2WI) sequence of 3.0 T MRI.MRI results were compared with histological findings.Macroscopic observation showed that SPIO-labeled MSCs were steered to the target region of cartilage defect.MRI revealed significantchanges in signal intensity (P＜0.01).HE staining exibited that a great number of MSCs formed a three-dimensional (3D) cell "sheet" structure at the chondral defect site.It was concluded that 0.57 T magnetic force permits spatial delivery of magnetically labeled MSCs to the target region in vitro.High-field MRI can serve as an very sensitive non-invasive technique for the visualization of SPIO-labeled MSCs.

Repair of cartilage defects using chondrocyte and osteoblast composites in vitro cultured in bioreactor / 中华创伤杂志

Objective To assess the feasibility of chondrocyte and osteoblast composites in vitro cultured in bioreactor in repairing cartilage defects.Methods Marrow mesenchymal stem cells were isolated and cultured in vitro,and then were induced to chondrocytes and osteoblasts by growth factor.Chondrocytes and osteoblasts were cocultured in bioreactor for 21 days to form the composites.The adhesion,extension and proliferation of chondrocytes and osteoblasts were observed under scanning electron microscope.The cartilage defects on canine model were repaired with the chondrocyte and osteoblast composites.Results The induced chondrocytes and osteoblasts had fine adhesion,extension and proliferation in the β-TCP scaffold.The repaired tissues in experimental group maintained their thickness to the full depth of the original tissues.A statistical difference was observed between negative control group and experimental group(q=12.337 0,P ＜ 0.01)and between blank control group and experimental group (q=31.539 3,P ＜0.01).Conclusion Perfusion bioreactor makes chondrocyte and osteoblast survive and proliferate in a three-dimensional scaffold and increases the composition rate of the chondrocyte and osteoblast.

Autologous Chondrocyte Implantation for Articular Cartilage Defect of Femoral Condyle / 대한정형외과학회잡지

PURPOSE: To evaluate the midterm clinical and histological results after autologous chondrocyte implantation (ACI) for an articular cartilage defect of the distal femoral condyle. MATERIALS AND METHODS: Twenty four cases with an articular cartilage defect (Outerbridge grade IV) of the femoral condyle that was confirmed by MRI and the arthroscopic findings underwent ACI. Their mean age at the time of surgery was 42.8 years and the mean follow-up period was 53.2 months (range, 20-82 months). At the last follow up, the articular cartilage view (SPGR) of MRI was examined and the clinical results were evaluated using the HSS and Lysholm scores. In 8 cases, second-look arthroscopy and biopsy were performed and evaluated using histological and histochemical methods. RESULTS: All cases except for one showed well-regenerated articular cartilage on MRI. All cases showed significant clinical improvement in the HSS and Lysholm scores (p<0.0001), with the exception of the Lysholm score of an articular cartilage fracture. Histologically, the regenerated tissue appeared to be a hyaline-like cartilage in all specimens. CONCLUSION: ACI for the treatment of articular cartilage defects of the distal femoral condyle showed a good clinical and MRI results. In OA, the clinical results were relatively acceptable after an associated high tibial valgus osteotomy. However, a longer term follow-up study will be needed to reach a final conclusion.

Cartilage Repair Using Mesenchymal Stem Cells

Articular cartilage defect rarely heals spontaneously due to its avascularity and low cellularity. Even small articular cartilage defects can develop into osteoarthritis, and subsequently, its management has been a major clinical concern. Although there are several treatment options for cartilage defect, no treatment has been established as a gold standard procedure. Bone marrow stimulation techniques which is equivalent to microfracture these days has been adapted as first line treatment, attributed to their technical easiness and minimal invasiveness to patients. However, this procedure has limitation in reproducing hyaline cartilage, so recent cell-based therapies using autologous chondrocytes or mesenchymal stem cells have drawn particular attention. MSCs regardless of its origin have shown significant potential for chondrogenesis. Novel approaches using MSCs as an alternative cell source for patient derived chondrocytes are currently on trial. In this review, stem cells from various origins considered as cell sources and potential application of mesenchymal stem cells to promote cartilage repair will be discussed. While differentiation of stem cell can be well controlled in vitro, it is not easy to predict the course of differentiation when the stem cell is transplanted. Some novel methods using physical stimulation and material based techniques for differentiation control are introduced in this context. Such differentiation control will be beneficial when it is adapted before transplantation. We call it preconditioning.

Effects of invigorating the kidney,promoting qi and activating blood method in repairing articular cartilage defects in rabbits with induced chondrocytes by bone marrow matrix stem cell / 中国矫形外科杂志

[Objective]To explore the effects of invigorating the kidney,promoting qi and activating blood method in repairing articular cartilage defects in rabbits with chodrocytes induced by bone marrow matrix stem cell.[Method]The complexes from seeding of chondrocytes and allograft chondrocytes encapsulated in collagen gel and cultured in Guyanding drug serum into CPPf/PLLA scaffolds were cultured in vitro for 3 weeks. Some complexes were observed with the phase-contrast microscope or scanning electron microscope and others were allotransplanted into articular cartilage defects in rabbits.The specimens harvested at 4,8,12 weeks were analyzed by observation,histology and type Ⅱ collagen immunohistochemistry.[Result]The induced chondrocytes were embedded in scaffolds evenly the formation,smoothness of the surface and integration with adjacent tissues of the hyaline cartilage-like tissues,distribution of type Ⅱ collagen in the matrix of the induced chondrocytes group were better than all those in the chondrocyte group.[Conclusion]The method of invigorating the kidney,promoting qi and activating blood has superiority in repairing articular cartilage defects over the traditional method.