Treatment Of Articular Cartilage Defects Research Articles

Arthroscopic autologous chondrocyte implantation in the hip for the treatment of full-thickness cartilage defects - A case series of 29 patients and review of the literature.

Purpose: Current literature indicates that the appropriate treatment of articular cartilage defects has significant influence on the postoperative outcome after hip arthroscopy. In the hip, arthroscopic treatment of cartilage defects is technically challenging, especially the autologous chondrocyte implantation/matrix-associated autologous chondrocyte implantation (ACI/MACI) procedures. The purpose of this prospective study was to introduce two injectable MACI products with self-adherent properties. Furthermore, we report short-term outcome and review the current literature. Methods: Full-thickness cartilage defects of 29 patients caused by the femoroacetabular impingement (FAI) were treated arthroscopically with an injectable MACI product in a two-step surgical procedure. The patient-related outcome was assessed with International Hip Outcome Tool (iHOT33), Euro-Quol group score (EQ-5D) and Non-Arthritic-Hip-Score (NAHS) at baseline, six weeks, six, 12 and 24 months. Results: Twenty-nine out of 46 patients (27 male/two female) with a mean age of 30.3 years (range 18–45 years) and an average defect size of 2.21 cm2 were available for follow-up after a mean of 19 months (range 6–24 months). All defects were located on the acetabulum International Cartilage Repair Society (ICRS) grade 3A–3D (nine 3A; eleven 3B; six 3C; three 3D). Twenty-six patients had associated labral pathology (23 repair 1–5 anchors; three partial trimming). Twenty-seven defects were caused by the FAI (20 CAM, six combined, one Pincer), two cases were of traumatic cause. An overall statistically significant improvement was observed for all assessment scores at an average follow-up of 19 months. Conclusion: In this study, we present short-term data of new arthroscopic injectable matrix-associated, autologous chondrocyte implants as a treatment option for full-thickness cartilage defects of the hip. All patient-administered assessment scores demonstrated an increase in activity level, quality of life and reduction of pain after a 19-month follow-up. Further randomized controlled trails (RCTs) with comparison of natural history, bone marrow stimulation techniques and MACI of the hip have to approve the results in long-term follow-up.

Autologous osteochondral transplantation (mosaicplasty) in articular cartilage defects of the patellofemoral joint: retrospective analysis of 33 cases.

The purpose of this retrospective study was to evaluate the results of osteochondral autografting (mosaicplasty) in isolated articular cartilage defects of the patellofemoral joint. Thirty-three patients who underwent mosaicplasty for patellofemoral (either patella or trochlea) cartilage defects (modified Outerbridge classification: grades III and IV) of the knee joint were retrospectively reviewed. There were 25 male and 8 female patients with a mean age of 31.3±6.7 (range 22-47) years. The average size of the lesion was 2.4±0.55cm2 (range 1.5-4.0). Patients with patellofemoral malalignment were excluded. All patients were followed at least one year with a mean of 19.3±4.3months (range 12-24months) using Lysholm knee score. The mean preoperative Lysholm knee score was 51.9±2.6 (47-58) points and increased to 85.5±4.2 (75-89) points at the final follow-up. There was a significant increase in Lysholm score during follow-up period (p=0.0001). The results were good in 24 cases and fair in 9 cases. No patients had poor results. No patients had infection. Five patients had postoperative mild painful hemarthrosis. Of these patients, four were treated with rest, ice, compression (elastic bandage) and elevation and the remaining one was treated by aspiration. No patients needed secondary open or arthroscopic drainage. No systemic complications occurred during the follow-up. Mosaicplasty is an effective technique for the treatment of articular cartilage defects of the patellofemoral joint knee which restores the joint function in a short period of follow-up. However, a meticulous surgical technique should be followed to restore the native articular surface and the congruity of the joint.

Dual Function of Glucosamine in Gelatin/Hyaluronic Acid Cryogel to Modulate Scaffold Mechanical Properties and to Maintain Chondrogenic Phenotype for Cartilage Tissue Engineering.

Glucosamine (GlcN) fulfills many of the requirements as an ideal component in scaffolds used in cartilage tissue engineering. The incorporation of GlcN in a gelatin/hyaluronic acid (GH) cryogel scaffold could provide biological cues in maintaining the phenotype of chondrocytes. Nonetheless, substituting gelatin with GlcN may also decrease the crosslinking density and modulate the mechanical properties of the cryogel scaffold, which may be beneficial as physical cues for chondrocytes in the scaffold. Thus, we prepared cryogel scaffolds containing 9% GlcN (GH-GlcN9) and 16% GlcN (GH-GlcN16) by carbodiimide-mediated crosslinking reactions at −16 °C. The crosslinking density and the mechanical properties of the cryogel matrix could be tuned by adjusting the content of GlcN used during cryogel preparation. In general, incorporation of GlcN did not influence scaffold pore size and ultimate compressive strain but increased porosity. The GH-GlcN16 cryogel showed the highest swelling ratio and degradation rate in hyaluronidase and collagenase solutions. On the contrary, the Young’s modulus, storage modulus, ultimate compressive stress, energy dissipation level, and rate of stress relaxation decreased by increasing the GlcN content in the cryogel. The release of GlcN from the scaffolds in the culture medium of chondrocytes could be sustained for 21 days for GH-GlcN16 in contrast to only 7 days for GH-GlcN9. In vitro cell culture experiments using rabbit articular chondrocytes revealed that GlcN incorporation affected cell proliferation, morphology, and maintenance of chondrogenic phenotype. Overall, GH-GlcN16 showed the best performance in maintaining chondrogenic phenotype with reduced cell proliferation rate but enhanced glycosaminoglycans (GAGs) and type II collagen (COL II) secretion. Quantitative real-time polymerase chain reaction also showed time-dependent up-regulation of cartilage-specific marker genes (COL II, aggrecan and Sox9) for GH-GlcN16. Implantation of chondrocytes/GH-GlcN16 constructs into full-thickness articular cartilage defects of rabbits could regenerate neocartilage with positive staining for GAGs and COL II. The GH-GlcN16 cryogel will be suitable as a scaffold for the treatment of articular cartilage defects.

Treatment of Articular Cartilage Defects With Microfracture and Autologous Matrix-Induced Chondrogenesis Leads to Extensive Subchondral Bone Cyst Formation in a Sheep Model

Background: Microfracture and the autologous matrix-induced chondrogenesis (AMIC) technique are popular for the treatment of articular cartilage defects. However, breaching of the subchondral bone plate could compromise the subchondral bone structure. Hypothesis: Microfracture and AMIC will cause deleterious effects on the subchondral bone structure. Study Design: Controlled laboratory study. Methods: A total of 36 sheep received an 8-mm-diameter cartilage defect in the left medial femoral condyle. Control animals (n = 12) received no further treatment, and the rest received 5 microfracture holes either with a type I/III collagen scaffold implanted (n = 12; AMIC group) or without the collagen scaffold (n = 12; microfracture group). Macroscopic infill of defects, histology, and histomorphometry of the subchondral bone were performed at 13 and 26 weeks postoperatively, and micro–computed tomography (CT) was also performed at 26 weeks postoperatively. Results: Microfracture and AMIC resulted in subchondral bone cyst formation in 5 of 12 (42%) and 11 of 12 (92%) specimens at 13 and 26 weeks, respectively. Subchondral bone changes induced by microfracture and AMIC were characterized by an increased percentage of bone volume, increased trabecular thickness, and a decreased trabecular separation, and extended beyond the area below the defect. High numbers of osteoclasts were observed at the cyst periphery, and all cysts communicated with the microfracture holes. Cartilage repair tissue was of poor quality and quantity at both time points and rarely reached the tidemark at 13 weeks. Conclusion: Microfracture technique caused bone cyst formation and induced severe pathology of the subchondral bone in a sheep model. Clinical Relevance: The potential of microfracture technique to induce subchondral bone pathology should be considered.

Treatment of Articular Cartilage Defects of the Knee With Microfracture and Enhanced Microfracture Techniques.

Chondral injuries in the knee are a common source of pain and morbidity. Treatment of symptomatic chondral defects is challenging due to the limited healing capacity of articular cartilage. Microfracture is the most common surgical technique used to treat chondral defects in the knee and utilizes marrow stimulation to generate a fibrocartilage repair. Microfracture has demonstrated good short-term postoperative outcomes. Long-term outcomes following microfracture are variable, with loss of improvement attributed to the poor mechanical qualities of the fibrous repair tissue. Current research is focusing on ways to optimize the repair environment after microfracture using biological scaffolds (enhanced microfracture) to facilitate chondrogenic differentiation and proliferation to improve the quality of repair tissue.

Intra-articular Injection of platelet-rich fibrin releasates in combination with bone marrow-derived mesenchymal stem cells in the treatment of articular cartilage defects: An in vivo study in rabbits.

The use of mesenchymal stem cells (MSCs), which can be differentiated into chondrocytes under specific conditions, has been proposed for the treatment of cartilage defects. Blood-derived platelet-rich fibrin releasate (PRFr), which is rich in growth factors and cytokines, may improve cartilage regeneration. In this study, the therapeutic effects of PRFr in combination with bone marrow-derived MSCs for articular cartilage regeneration were evaluated in a rabbit model. Critical osteochondral defects were surgically created in the femoral condyle of the rabbits, and 3 × 106 of MSCs, 0.8 mL of PRFr, or a combination of MSCs and PRFr were injected intra-articularly and one week after first administration. The animals were sacrificed 12 weeks postoperatively, and the regenerated cartilages were assessed by gross inspection and histological examination. No treatment-related adverse events were noted in any of the rabbits. The size of the defect decreased and the volume of regenerated cartilage increased in the medial femoral condyles of the MSCs + PRFr group. Relative to the MSCs or PRFr group, histological examination demonstrated that the MSCs + PRFr group had thicker hyaline-like cartilaginous tissue with normal glycosaminoglycan production. Grading scores revealed that MSCs + PRFr injection had better matrix, cell distribution, and surface indices than other groups. The results showed that intra-articular injections of MSCs + PRFr into the knee can reduce cartilage defects by regenerating hyaline-like cartilage without adverse events. This approach may provide an alternative method of autologous chondrocyte implantation to repair cartilage defects with an unlimited source of cells and releasate. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1536-1543, 2017.

Fresh Osteochondral Allograft Transplantation for Treatment of Articular Cartilage Defects of the Knee

Articular cartilage damage of the knee can cause severe morbidity. Owing to its avascular nature, articular cartilage has limited potential for self-healing and increased propensity to progress to osteoarthritis. Treatment of large, full-thickness cartilage defects is still a challenge for orthopaedic surgeons but has recently achieved high success rates with the use of osteochondral allografts. This article details our technique of osteochondral allograft transplantation for the treatment of articular cartilage defects of the knee.

Return to Sports Activity and Work After Autologous Chondrocyte Implantation of the Knee

Background: Autologous chondrocyte implantation (ACI) has been associated with satisfying results in everyday activities. Clinical results after ACI treatment of femorotibial lesions are superior in comparison with patellofemoral lesions. There is limited information regarding at which level recreational, amateur, and professional athletes can resume sports and physical activities as well as work after ACI and what parameters influence return to work and sports. Hypothesis: Return to sports activity and work is dependent on defect characteristics such as location and size. Study Design: Case series; Level of evidence, 4. Methods: A total of 130 patients with isolated full-thickness cartilage defects of the knee joint treated with ACI between June 2000 and October 2007 were retrospectively studied by an established questionnaire that assessed sports-specific questions such as frequency, duration, and intensity. Engagement in 32 different sports disciplines was evaluated. In addition, work-specific data were evaluated according to classifications established by the REFA Association. Results were evaluated depending on patient- and defect-specific parameters. Results: The mean ± SD patient age at ACI was 36.2 ± 9.2 years, with a mean defect size of 4.4 ± 1.7 cm2. Defects were located at the femorotibial compartment in 55.7% of cases, whereas lesions of the patellofemoral compartment were found in 44.3%. Mean duration of inability to work after ACI was 13.6 ± 11.0 weeks and did not appear to be influenced by patient age. Defect location and defect size did not appear to significantly influence return-to-work rates, but work intensity before surgery significantly influenced return-to-work rates and duration of absence from work. Workplace adaptations were necessary in only 9.2% of cases postoperatively. With regard to postoperative sports activity, 73.1% of patients were able to return to sports. Neither defect location nor size significantly influenced return to physical activity. Patients participated in a mean of 2.3 different sports during their lifetime. Both duration of exercise and number of sessions per week significantly decreased from before to after surgery. Detailed analysis of 32 different sporting activities revealed that high-impact as well as start-stop sports were generally abandoned in favor of endurance and low-intensity exercises. A lifetime level of competitiveness was maintained in 31.3% of cases, while return to elite sports at the time of the survey became highly unlikely (0.8%). Conclusion: The study results illustrate that treatment of articular cartilage defects of the knee joint leads to satisfactory results concerning everyday activities. With the exception of physical labor, no essential adaptations needed to be made at work. Regarding sports activity, return to low- and moderate-intensity levels appears realistic in the majority of cases, whereas the likelihood of returning to activities with high stress applied on the knee joint is low. Neither defect location nor size appears to significantly influence postoperative sports activity or return-to-work rates.

Effect of Dynamic Culture and Periodic Compression on Human Mesenchymal Stem Cell Proliferation and Chondrogenesis.

We have recently developed a bioreactor that can apply both shear and compressive forces to engineered tissues in dynamic culture. In our system, alginate hydrogel beads with encapsulated human mesenchymal stem cells (hMSCs) were cultured under different dynamic conditions while subjected to periodic, compressive force. A customized pressure sensor was developed to track the pressure fluctuations when shear forces and compressive forces were applied. Compared to static culture, dynamic culture can maintain a higher cell population throughout the study. With the application of only shear stress, qRT-PCR and immunohistochemistry revealed that hMSCs experienced less chondrogenic differentiation than the static group. The second study showed that chondrogenic differentiation was enhanced by additional mechanical compression. After 14days, alcian blue staining showed more extracellular matrix formed in the compression group. The upregulation of the positive chondrogenic markers such as Sox 9, aggrecan, and type II collagen were demonstrated by qPCR. Our bioreactor provides a novel approach to apply mechanical forces to engineered cartilage. Results suggest that a combination of dynamic culture with proper mechanical stimulation may promote efficient progenitor cell expansion in vitro, thereby allowing the culture of clinically relevant articular chondrocytes for the treatment of articular cartilage defects.

Effect of Longan polysaccharides on proliferation and phenotype maintenance in rabbit articular chondrocytes in vitro.

For autologous chondrocyte implantation (ACI) to restore cartilage defect, limited cell numbers and dedifferentiation of chondrocytes are the major difficulties. An alternative is the use of growth factors, but the high cost and potential tumorigenesis are the major obstacles. To ensure successful ACI therapy, it is of significance to find effective substituted pro-chondrogenic agent. Polysaccharides from plant extract have low toxicity and few undesirable side effects, which were reported to facilitate cartilage regeneration. In this study, we investigated the effect of Longan polysaccharides (LP) on rabbit articular chondrocytes through examination of the cell proliferation, morphology, viability, glycosaminoglycan synthesis and cartilage-specific gene expression. Results showed that close to the positive group which used the growth factor of TGF-β, LP could effectively promote chondrocytes growth and enhance secretion and synthesis of cartilage extracellular matrix by up-regulating expression levels of aggrecan, collagen II and sox9 compared to the negative control. Expression of collagen I gene was effectively down-regulated, demonstrating the inhibition of chondrocytes dedifferentiation by LP. Hypertrophy that might lead to chondrocyte ossification was also undetectable in LP groups. Range of 4.69-18.76µg/ml was recommended dose of LP, among which the most profound response was observed with 9.38μg/ml. All the evidences revealed that LP may replace the growth factors to be applied in ACI therapy. This study might provide a basis for development of a novel agent in the treatment of articular cartilage defect.

Three-dimensional dynamic fabrication of engineered cartilage based on chitosan/gelatin hybrid hydrogel scaffold in a spinner flask with a special designed steel frame.

Cartilage transplantation using in vitro tissue engineered cartilage is considered a promising treatment for articular cartilage defects. In this study, we assessed the advantages of adipose derived stem cells (ADSCs) combined with chitosan/gelatin hybrid hydrogel scaffolds, which acted as a cartilage biomimetic scaffold, to fabricate a tissue engineered cartilage dynamically in vitro and compared this with traditional static culture. Physical properties of the hydrogel scaffolds were evaluated and ADSCs were inoculated into the hydrogel at a density of 1×10(7) cells/mL and cultured in a spinner flask with a special designed steel framework and feed with chondrogenic inductive media for two weeks. The results showed that the average pore size, porosity, swelling rate and elasticity modulus of hybrid scaffolds with good biocompatibility were 118.25±19.51 μm, 82.60±2.34%, 361.28±0.47% and 61.2±0.16 kPa, respectively. ADSCs grew well in chitosan/gelatin hybrid scaffold and successfully differentiated into chondrocytes, showing that the scaffolds were suitable for tissue engineering applications in cartilage regeneration. Induced cells cultivated in a dynamic spinner flask with a special designed steel frame expressed more proteoglycans and the cell distribution was much more uniform with the scaffold being filled mostly with extracellular matrix produced by cells. A spinner flask with framework promoted proliferation and chondrogenic differentiation of ADSCs within chitosan/gelatin hybrid scaffolds and accelerated dynamic fabrication of cell-hydrogel constructs, which could be a selective and good method to construct tissue engineered cartilage in vitro.

405. Enhanced Chondrogenic Potential of Human Bone Marrow Aspirates Upon rAAV-Mediated Overexpression of IGF-I

Genetic modification of human bone marrow aspirates is an attractive strategy as a convenient, one-step treatment of articular cartilage defects. Here, we tested whether overexpression of the mitogenic and pro-anabolic IGF-I factor via rAAV vectors enhances the reparative activities of human bone marrow aspirates. Aspirates obtained from the distal femurs of patients undergoing total knee arthroplasty were directly transduced with an rAAV-hIGF-I vector vs. control rAAV-lacZ transduction and maintained in chondrogenic medium for up to 21 days. Transgene expression was monitored by immunohistochemistry on paraffin-embedded sections of aspirates also stained with toluidine blue and for type-II collagen immunoreactivity. The DNA and proteoglycan contents were monitored by Hoechst 22358 assay and binding to DMMB, respectively. Real-time RT-PCR was performed using the 2-ΔΔCt method to monitor the expression of SOX9, ACAN, COL2A1, COL1A1, and COL10A1, with GAPDH as a control for normalization, by measuring the fold inductions in IGF-I vs. lacZ conditions. Each condition was performed in duplicate in three experiments. The t-test was employed with P ≤ 0.05 considered statistically significant. Effective production of IGF-I was achieved in IGF-I- vs. lacZ-treated aspirates. Enhanced chondrogenic differentiation was observed after 21 days in the aspirates with rAAV-hIGF-I, as noted by more robust toluidine blue staining and stronger type-II collagen immunostaining compared with rAAV-lacZ. IGF-I treatment also increased the DNA and proteoglycan contents in the aspirates vs. lacZ. These findings were corroborated by real-time RT-PCR analysis showing higher levels of SOX9, ACAN, and COL2A1 expression with IGF-I that also increased the levels of COL1A1 and COL10A1. Overexpression of IGF-I via rAAV is thus capable of stimulating the metabolic and chondrogenic activities in human bone marrow aspirates. Regulation of growth factor expression will be necessary to contain terminal differentiation and hypertrophy for translation of the approach in cartilage defects.

Intra-Articular Injection of Synovium-Derived Mesenchymal Stem Cells with Hyaluronic Acid Can Repair Articular Cartilage Defects in a Canine Model

Objective: The purpose of this study was to evaluate effectiveness of intra-articular injection of synovium-derived mesenchymal stem cells (SMSCs) and hyaluronic acid (HA) for the treatment of articular cartilage defects in a canine model. Methods: Forty-eight knees of 24 beagle dogs were randomly assigned to 16 groups (n=3) according to both the number of injected SMSCs (0.5×105 cells, 5×106 cells, 5×107 cells) and the concentration of HA (0%, 0.01%, 0.1%, 0.5%). A partial-thickness cartilage defect was created in the medial femoral condyle under arthroscopy. After seven weeks, autologous SMSCs with or without 1 ml HA were percutaneously injected into the injured knee. In the control group, 1 ml saline was injected. Twelve weeks after the injection, evaluation was performed using the International Cartilage Repair Society (ICRS) visual assessment scale and the modified O’Driscoll histological score. Results: The mean ICRS visual assessment scale and the mean modified O’Driscoll histological score were 1.0 ± 0.00 and 11.0 ± 0.00 in the control group. On the other hand, the mean ICRS visual assessment scale and the mean modified O’Driscoll histological score were 7.3 ± 3.21 and 30.7 ± 7.23 in the group injected with 5×106 cells and 0.01% HA. Conclusion:Intra-articular injection of SMSCs with HA may be effective for stimulating articular cartilage repair. Our results suggest that there is an ideal combination of the number of SMSCs and the concentration of HA for promoting particular cartilage repair.

Covalently conjugated transforming growth factor-β1 in modular chitosan hydrogels for the effective treatment of articular cartilage defects.

Approaches to control precisely growth factor presentation to a tissue defect in a sustained fashion are of increasing interest for a number of complex tissue engineering applications. Although transforming growth factor beta-1 (TGF-β1) plays a key role in promoting chondrogenesis, the therapeutic use of TGF-β1 is limited by its inherent protein instability, requiring high amounts of the protein that can cause adverse side effects with inefficient cartilage formation. In this work, we have developed strategies to stabilize TGF-β1 signaling in the injectable, visible blue light inducible chitosan (MeGC) hydrogel system for specific use in cartilage regeneration. We successfully modulated delivery of TGF-β1 with reduced burst release in a complex biological environment of serum and cells by covalently conjugating the protein to MeGC hydrogels with preserving type II collagen, one of the major cartilaginous extracellular matrix (ECM) components. The hydrogel system supported cellular condensation and deposition of cartilaginous ECM by encapsulating adipose derived stem cells in vitro. We confirmed further the ability of these TGF-β1 functionalized hydrogel systems to promote cartilage regeneration in challenging healing environments such as in a rat partial-thickness chondral defect model which present a limited source of subchondral bone marrow elements. These results suggest a new injectable delivery modality of therapeutic agents to improve clinical cartilage repair.

Application of Adult Stem Cells in Medicine.

Application of Adult Stem Cells in Medicine.

Results at 10-14years after microfracture treatment of articular cartilage defects in the knee.

To evaluate the long-term clinical outcome after microfracture treatment of focal chondral defects of the knee and to investigate possible early determinants of the outcome. A prospective cohort of 110 patients, treated with microfracture, was evaluated at a median of 12years (range 10-14) by Lysholm score, VAS of knee function and VAS of knee pain. Pre- and perioperative information was collected, and additional surgery to the same knee during the follow-up period was recorded. Analysis of variance and paired t test were used for comparison of the long-term data to results from the baseline examination and a former 5-year (midterm) follow-up evaluation. Forty-three patientsneeded additional surgery to the knee including seven knee replacements. Fifty had a poor long-term outcome-defined as a knee replacement surgery or Lysholm score below 64. A poor result was more common in subgroups with mild degenerative changes in the cartilage surrounding the treated defect, concurrent partial meniscectomy, poor baseline Lysholm score or long-standing knee symptoms. The Lysholm score, function VAS and pain VAS all significantly improved from the baseline values to the mean scores of 65 (SD 24), 65 (SD 24) and 31 (SD 24), respectively, at the long-term evaluation. The long-term scores did not differ significantly from the midterm scores. The outcome scores improved significantly from baseline to the long-term evaluation and were not different from the midterm outcome. Still, a normal knee function was generally not achieved, and many patients had further surgery. The results call for more research and, at present, caution in recommending microfracture in articular cartilage defects, especially in subgroups with worse prognosis. Case series, Level IV.

Direct bone morphogenetic protein 2 and Indian hedgehog gene transfer for articular cartilage repair using bone marrow coagulates

Bone morphogenetic protein 2 (BMP-2, encoded by BMP2) and Indian hedgehog protein (IHH, encoded by IHH) are well known regulators of chondrogenesis and chondrogenic hypertrophy. Despite being a potent chondrogenic factor BMP-2 was observed to induce chondrocyte hypertrophy in osteoarthritis (OA), growth plate cartilage and adult mesenchymal stem cells (MSCs). IHH might induce chondrogenic differentiation through different intracellular signalling pathways without inducing subsequent chondrocyte hypertrophy. The primary objective of this study is to test the efficacy of direct BMP2 and IHH gene delivery via bone marrow coagulates to influence histological repair cartilage quality in vivo. Vector-laden autologous bone marrow coagulates with 10(11) adenoviral vector particles encoding BMP2, IHH or the Green fluorescent protein (GFP) were delivered to 3.2 mm osteochondral defects in the trochlea of rabbit knees. After 13 weeks the histological repair cartilage quality was assessed using the ICRS II scoring system and the type II collagen positive area. IHH treatment resulted in superior histological repair cartilage quality than GFP controls in all of the assessed parameters (with P < 0.05 in five of 14 assessed parameters). Results of BMP2 treatment varied substantially, including severe intralesional bone formation in two of six joints after 13 weeks. IHH gene transfer is effective to improve repair cartilage quality in vivo, whereas BMP2 treatment, carried the risk intralesional bone formation. Therefore IHH protein can be considered as an attractive alternative candidate growth factor for further preclinical research and development towards improved treatments for articular cartilage defects.

Effect of epigallocatechin-3-gallate on proliferation and phenotype maintenance in rabbit articular chondrocytes in vitro.

In autologous chondrocyte implantation (ACI) to restore defective cartilage, limited cell numbers and dedifferentiation of chondrocytes are the major difficulties. An alternative is the use of growth factors, but their high cost and potential for tumorigenesis are major obstacles. To ensure successful ACI therapy, it is important to find an effective substitute pro-chondrogenic agent. Epigallocatechin-3-gallate (EGCG), one of the green tea catechins, has been widely investigated in studies of interleukin-1β-induced chondrocytes. In the present study, the effects of EGCG on rabbit articular chondrocytes were investigated through the examination of cell proliferation, morphology, glycosaminoglycan synthesis and cartilage-specific gene expression. The results showed that EGCG could effectively promote chondrocyte growth and enhance the secretion and synthesis of the cartilage extracellular matrix by upregulating expression levels of aggrecan, collagen II and Sox9 genes. Expression of the collagen I gene was downregulated, which showed that EGCG effectively inhibited the dedifferentiation of chondrocytes. Hypertrophy, which may lead to chondrocyte ossification, was also undetectable in the EGCG groups. In conclusion, the recommended dose of EGCG was found to be in the range of 5 to 20 μM, with the most marked response observed with 10 μM. The present study may provide a basis for the development of a novel agent as a substitute for growth factors in the treatment of articular cartilage defects.

Promoting increased mechanical properties of tissue engineered neocartilage via the application of hyperosmolarity and 4α-phorbol 12,13-didecanoate (4αPDD)

Osteoarthritis, a degenerative disease of the load-bearing joints, greatly reduces quality of life for millions of Americans and places a tremendous cost on the American healthcare system. Due to limitations of current treatments, tissue engineering of articular cartilage may provide a promising therapeutic option to treat cartilage defects. However, cartilage tissue engineering has yet to recapitulate the functional properties of native tissue. During normal joint loading, cartilage tissue experiences variations in osmolarity and subsequent changes in ionic concentrations. Motivated by these known variations in the cellular microenvironment, this study sought to improve the mechanical properties of neocartilage constructs via the application of hyperosmolarity and transient receptor potential vanilloid 4 (TRPV4) channel activator 4α-phorbol 12,13-didecanoate (4αPDD). It was shown that 4αPDD elicited significant increases in compressive properties. Importantly, when combined, 4αPDD positively interacted with hyperosmolarity to modulate its effects on tensile stiffness and collagen content. Thus, this study supports 4αPDD-activated channel TRPV4 as a purported mechanosensor and osmosensor that can facilitate the cell and tissue level responses to improve the mechanical properties of engineered cartilage. To our knowledge, this study is the first to systematically evaluate the roles of hyperosmolarity and 4αPDD on the functional (i.e., mechanical and biochemical) properties of self-assembled neotissue. Future work may combine 4αPDD-induced channel activation with other chemical and mechanical stimuli to create robust neocartilages suitable for treatment of articular cartilage defects.

A novel synthesized sulfonamido-based gallic acid – LDQN-C: Effects on chondrocytes growth and phenotype maintenance

Chondrocyte based therapy is promising to treat symptomatic chondral and osteochondral lesions. Growth factors to accelerate the proliferation and retain the phenotype of chondrocytes in vitro are imperative. However, the high cost and rapid degradation of growth factors limited their further application. Therefore, it is significant to find substitutes that can preserve chondrocytes phenotype and ensure sufficient cells for cytotherapy. Antioxidant and anti-inflammatory agents or their derivatives that have effect on arthritis may be an alternative. In this study, we synthesized sulfonamido-based gallate – LDQN-C and investigated its effect on rat articular chondrocytes through examination of the cell proliferation, morphology, viability, glycosaminoglycans (GAGs) synthesis and cartilage specific gene expression. Results showed that LDQN-C could enhance secretion and synthesis of cartilage extracellular matrix (ECM) by up-regulating expression levels of aggrecan, collagen II and Sox9 genes compared to the GA treated group and control group. Expression of collagen type II was effectively up-regulated while collagen I was down-regulated, which demonstrated that the inhibition of chondrocytes dedifferentiation by LDQN-C. Range of 1.36×10−9M to 1.36×10−7M is recommended dose of LDQN-C, among which the most profound response was observed with 1.36×10−8M. GA at concentration of 0.125μg/mL was compared. This study might provide a basis for the development of a novel agent for the treatment of articular cartilage defect.