Cartilage Defects In Rabbits Research Articles

Cell factory-derived bioactive molecules with polymeric cryogel scaffold enhance the repair of subchondral cartilage defect in rabbits

We have explored the potential of cell factory-derived bioactive molecules, isolated from conditioned media of primary goat chondrocytes, for the repair of subchondral cartilage defects. Enzyme-linked immunosorbent assay (ELISA) confirms the presence of transforming growth factor-β1 in an isolated protein fraction (12.56 ± 1.15 ng/mg protein fraction). These bioactive molecules were used alone or with chitosan-agarose-gelatin cryogel scaffolds, with and without chondrocytes, to check whether combined approaches further enhance cartilage repair. To evaluate this, an in vivo study was conducted on New Zealand rabbits in which a subchondral defect (4.5 mm wide × 4.5 mm deep) was surgically created. Starting after the operation, bioactive molecules were injected at the defect site at regular intervals of 14 days. Histopathological analysis showed that rabbits treated with bioactive molecules alone had cartilage regeneration after 4 weeks. However, rabbits treated with bioactive molecules along with scaffolds, with or without cells, showed cartilage formation after 3 weeks; 6 weeks after surgery, the cartilage regenerated in rabbits treated with either bioactive molecules alone or in combinations showed morphological similarities to native cartilage. No systemic cytotoxicity or inflammatory response was induced by any of the treatments. Further, ELISA was done to determine systemic toxicity, which showed no difference in concentration of tumour necrosis factor-α in blood serum, before or after surgery. In conclusion, intra-articular injection with bioactive molecules alone may be used for the repair of subchondral cartilage defects, and bioactive molecules along with chondrocyte-seeded scaffolds further enhance the repair. Copyright © 2015 John Wiley & Sons, Ltd.

Repair of knee articular cartilage defects with bone marrow-derived mesenchymal stem cells and bioprotein gel compound in rabbits

Objective To investigate the role of bone marrow-derived mesenchymal stem cells (BMSCs) compounded with bioprotein gel (Bg) in repair of knee articular cartilage defects of rabbits. Methods Bilateral femoral condylar cartilage defect models (3.5 mm in diameter and 3 mm in depth) were established in 36 healthy New Zealand rabbits. Animals were divided into three groups of 12 rabbits each according to the random number table: BMSCs-Bg group, Bg group and blank control group. Effect of repair was evaluated by anatomic observation and histological examination at 4, 8, 12 and 16 weeks after operation and by articular cartilage histological hemi-quantitative scoring system. Results Hyaline-like cartilage was noted in BMSCs-Bg group at 4 weeks postoperatively, got close to the normal at 8 and 12 weeks and showed no disintegration at 16 weeks. Only fibrous tissue or fibrocartilage was observed in other 2 groups. In BMSCs-Bg group histology scores were (4.5±0.1)points, (4.9±0.1)points, (5.5±0.1)points, and (6.2±0.1)points respectively at 4, 8, 12 and 16 weeks, higher than those in other 2 groups (P<0.05). Besides, the histology scores were higher in Bg group than in blank control group but the differences were insignificant. Conclusion BMSCs-Bg compound can well repair the articular cartilage defect in a short-term period, when Bg contributes to cartilage generation as a good cell carrier. Key words: Cartilage; Mesenchymal stem cells; Fibrin tissue adhesive; Repair

Effects of Phosphorylatable Short Peptide-Conjugated Chitosan-Mediated IL-1Ra and igf-1 Gene Transfer on Articular Cartilage Defects in Rabbits

Previously, we reported an improvement in the transfection efficiency of the plasmid DNA-chitosan (pDNA/CS) complex by the utilization of phosphorylatable short peptide-conjugated chitosan (pSP-CS). In this study, we investigated the effects of pSP-CS-mediated gene transfection of interleukin-1 receptor antagonist protein (IL-1Ra) combined with insulin-like growth factor-1 (IGF-1) in rabbit chondrocytes and in a rabbit model of cartilage defects. pBudCE4.1-IL-1Ra+igf-1, pBudCE4.1-IL-1Ra and pBudCE4.1-igf-1 were constructed and combined with pSP-CS to form pDNA/pSP-CS complexes. These complexes were transfected into rabbit primary chondrocytes or injected into the joint cavity. Seven weeks after treatment, all rabbits were sacrificed and analyzed. High levels of IL-1Ra and igf-1 expression were detected both in the cell culture supernatant and in the synovial fluid. In vitro, the transgenic complexes caused significant proliferation of chondrocytes, promotion of glycosaminoglycan (GAG) and collagen II synthesis, and inhibition of chondrocyte apoptosis and nitric oxide (NO) synthesis. In vivo, the exogenous genes resulted in increased collagen II synthesis and reduced NO and GAG concentrations in the synovial fluid; histological studies revealed that pDNA/pSP-CS treatment resulted in varying degrees of hyaline-like cartilage repair and Mankin score decrease. The co-expression of both genes produced greater effects than each single gene alone both in vitro and in vivo. The results suggest that pSP-CS is a good candidate for use in gene therapy for the treatment of cartilage defects and that igf-1 and IL-1Ra co-expression produces promising biologic effects on cartilage defects.

Comparison of repair between cartilage and osteocartilage defects in rabbits using similarly manipulated scaffold-free cartilage-like constructs

BackgroundArticular cartilage has a limited capacity for spontaneous repair, and its repair remains a clinical challenge. The purpose of this study was to prepare scaffold-free cartilage-like constructs and evaluate the feasibility of their use for the treatment of cartilage and osteocartilage defects in vivo. MethodsThe scaffold-free constructs were prepared by chondrocytes isolated from the articular cartilage of rabbits using a high-density three-dimensional culture system. Two different defects, i.e., a chondral defect without oozing blood and an osteochondral defect with oozing blood, of 4-mm diameter, were created on the patellar groove of rabbits and forwarded to in vivo trials. In each defect, the constructs cut into 4-mm-diameter cylinders were grafted at the bottom of the defects. As a control, defects were only made on the contralateral knee joint in each rabbit. At 2, 4, 8 and 12 weeks after surgery, six rabbits in each group were evaluated macroscopically and histologically. ResultsIn vitro, histological examination revealed that the constructs have the character of hyaline cartilage with a potential adhesiveness to surrounding tissue. In vivo, in two control groups, incomplete spontaneous cartilage repair was observed in the osteochondral defects, whereas no repair was observed in the chondral defects. In the two treated groups, the surviving constructs in chondral defects showed significantly better repair compared to those in osteochondral defects. ConclusionsIt is possible for a chondral defect to be repaired by scaffold-free constructs in certain conditions. Establishing the optimal environment suitable for cartilage repair is warranted.

Combined effects of connective tissue growth factor-modified bone marrow-derived mesenchymal stem cells and NaOH-treated PLGA scaffolds on the repair of articular cartilage defect in rabbits.

In cartilage tissue engineering using stem cells, it is important to stimulate proliferation and control the differentiation of stem cells to specific lineages. Here we reported a combined technique for articular cartilage repair, consisting of bone marrow mesenchymal stem cells (BMMSCs) transfected with connective tissue growth factor (CTGF) gene and NaOH-treated poly(lactic-co-glycolic) acid (PLGA) scaffolds. In the present study, BMMSCs or CTGF-modified BMMSCs seeded on PLGA or NaOH-treated PLGA scaffolds were incubated in vitro and NaOH-treated PLGA significantly stimulated proliferation of BMMSCs, while CTGF gene transfer promoted chondrogenic differentiation. The effects of the composite on the repair of cartilage defects were evaluated in rabbit knee joints in vivo. Full-thickness cartilage defects (diameter: 5 mm; depth: 3 mm) were created unilaterally in the patellar groove. Defects were either left empty (n = 18) or implanted with BMMSCs/PLGA (n = 18), BMMSCs/NaOH-treated PLGA (n = 18), or CTGF-modified BMMSCs/NaOH-treated PLGA (n = 18). The defect area was examined grossly, histologically, and mechanically at 6, 12, and 24 weeks postoperatively. Implanted cells were tracked using adeno-LacZ labeling at 6 weeks after implantation. Overall, the CTGF-modified BMMSCs/NaOH-treated PLGA group showed successful hyaline-like cartilage regeneration similar to normal cartilage, which was superior to the other groups using gross examination, qualitative and quantitative histology, and mechanical assessment. The in vivo viability of the implanted cells was demonstrated by their retention for 6 weeks after implantation. These findings suggested that a combination of CTGF-modified BMMSCs and NaOH-treated PLGA may be an alternative treatment for large osteochondral defects in high-loading sites.

Histology research on repairing of rabbit articular cartilage defects with naringin and tissue engineering cartilage

At present, there are many methods to treat cartilage defects, but none radically repairs the articular cartilage defects. To histologically verify the effect of naringin combined with tissue engineering cartilage on the repair of rabbit articular cartilage defects. Rabbit bone marrow mesenchymal stem cells following in vitro proliferation were compounded onto acellular dermal matrix, which was then implanted into rabbit knee cartilage defects. Naringin was also given by lavage. Hematoxylin-eosin staining, Masson trichrome staining, toluidine blue dyeing, type II collagen staining and type X collagen staining were performed in the repaired tissue. After 8 weeks post-surgery, the defects repaired with the naringin and stem cells composite were turned into milky-white and transparent smooth tissue. The defective tissue which was repaired, was very similar to normal cartilage tissue, with smooth surface. After the histology research, we found that the defect tissue was filled with new cartilage tissue. Results indicated that naringin combined with tissue engineering cartilage can promote the repair of articular cartilage defects in rabbits. Subject headings: bone marrow; mesenchymal stem cells; dermis; tissue engineering; cartilage, articular; polypodiaceae Funding: Fund for Young Teachers by Beijing University of Chinese Medicine, No. JYBZZ-JS060 Li CG, Qu Y, Ye C, Chen J, Wang FX, Li PY, Li SH, Ren JP, Qi J. Histology research on repairing of rabbit articular cartilage defects with naringin and tissue engineering cartilage. Zhongguo Zuzhi Gongcheng Yanjiu. 2014;18(20): 3165-3171.

Reparation of chondral defects in rabbits by autologous and allogenous chondrocytes seeded on collagen/hyaluronan scaffold or suspended in fibrin glue

Abstract The topic of the study was to verify in vivo survival of in vitro cultured autologous and allogenous chondrocytes suspended in a fibrin glue Beriplast® or seeded on Collagen type I-Hyaluronan (Col type I-HYA) scaffolds for the regeneration of articular cartilage defects in rabbits. The study was carried out on 15 domestic rabbits randomly assigned to five groups (n = 3 in each) with different treatments of artificially created chondral defects (ChD´s). These defects were made in a non-load-bearing area of medial condyle of the distal femur, and were treated as follows: 1st and 3rd group: the ChD´s were filled with autologous or allogenous chondrocytes seeded on Col type I-HYA scaffolds, respectively. The scaffolds were fixed to the ChD´s by fibrin glue Beriplast®; 2nd and 4th group: the ChD´s were filled with a suspension of autologous or allogenous chondrocytes in fibrin glue Beriplast®, respectively, and they were immediately covered by unseeded Col type I-HYA scaffolds; Control group: the ChD´s were left to heal spontaneously without any treatment. Macroscopical, histological and immunohistochemical analyses of the ChD´s were performed 12 months after the treatment. In all treated groups, the chondrocytes were capable to proliferate and produce the cartilage extracellular matrix, including proteoglycans and type II collagen, as compared to the control “untreated” group. On the other hand, the production of hyaline-like cartilage tissue confirmed that both therapeutic methods using autologous chondrocytes can be applied successfully for the treatment of chondral defects in rabbits.

Intra-articular injection of synovium-derived mesenchymal stem cells and hyaluronic acid promote regeneration of massive cartilage defects in rabbits.

IntroductionThe purpose of this study was to investigate whether intra-articular injection of synovium-derived mesenchymal stem cells (SD MSCs) with low molecular weight hyaluronic acid (HA) could promote regeneration of massive cartilage in rabbits.Material and methodsThe SD MSCs were harvested from the knees of 10 Flemish giant rabbits, expanded in culture, and characterized. A reproducible 4-mm cylindrical defect was created in the intercondylar groove area using a kit for the mosaic chondroplasty of femoral condyle COR (De Puy, Mitek). The defect was made within the cartilage layer without destruction of subchondral bone. Two weeks after the cartilage defect, SD MSCs (2 × 106 cell/0.15 ml) were suspended in 0.5% low molecular weight HA (0.15 ml) and injected into the left knee, and HA solution (0.30 ml) alone was placed into the right knee. Cartilage regeneration in the experimental and control groups were evaluated by macroscopically and histologically at 10, 30, and 60 days.ResultsOn day 10, after intra-articular injection of SD MSCs, we observed an early process of cartilage regeneration in the defect area. Histological studies revealed that cartilage defect was covered by a thin layer of spindle-shaped undifferentiated cells and proliferated chodroblasts. In contrast, an injection of HA did not induce reparation of cartilage in the defect area. At 30 days, macroscopic observation showed that the size of cartilage defect after SD MSC injection was significantly smaller than after HA injection. Histological score was also better in the MSC-treated intercondylar defect. At 60 days after MSC treatment, cartilage defect was nearly nonexistent and looked similar to an intact cartilage.ConclusionThus, intra-articular injection of SD MSCs can adhere to the defect in the intercondylar area, and promote cartilage regeneration in rabbits.

Study of human acellular amniotic membrane loading bone marrow mesenchymal stem cells in repair of articular cartilage defect in rabbits.

The aim of this study was to investigate the repair effect of human acellular amniotic membrane (HAAM) loading bone marrow mesenchymal stem cells (BMSCs) on articular cartilage defect in rabbits. Rabbit BMSCs were isolated and cultured, and they were then inoculated on HAAM to prepare the complex of HAAM and BMSCs. Twenty-four rabbits were randomly divided into groups A and B, with 12 animals in each group. The left and right sides were used as the experimental and control sides, respectively. The models of bilateral articular cartilage defect were established. The defect areas on the experimental side in groups A and B were implanted with the complex of HAAM and BMSCs and HAAM alone, respectively. The control sides of the two groups were not implanted with any material. In the 8th and 12th week after surgery, gross observation, histological examination and cartilage defect scoring were performed. In the 8th and 12th postoperative week, gross observation and histological observation showed that dense cartilage-like cells appeared in group A but not in group B, indicating preferable cartilage repair. The cartilage defect score on the experimental side in group A was 5.31 ± 0.68 in the 8th week and 3.23 ± 0.52 in the 12th week, and that in group A was significantly lower than in group B (P < 0.05). HAAM loading BMSCs has a good repair effect on articular cartilage defect under an in vitro environment.

Repair of articular cartilage defects by tissue-engineered cartilage constructed with adipose-derived stem cells and acellular cartilaginous matrix in rabbits.

After injury, inflammation, or degeneration, articular cartilage has limited self-repair ability. We aimed to explore the feasibility of repair of articular cartilage defects with tissue-engineered cartilage constructed by acellular cartilage matrices (ACMs) seeded with adipose-derived stem cells (ADSCs). The ADSCs were isolated from 3-month-old New Zealand albino rabbit by using collagenase and cultured and amplified in vitro. Fresh cartilage isolated from adult New Zealand albino rabbit were freeze-dried for 12 h and treated with Triton X-100, DNase, and RNase to obtain ACMs. ADSCs were seeded in the acellular cartilaginous matrix at 2x10(7)/mL, and cultured in chondrogenic differentiation medium for 2 weeks to construct tissue-engineered cartilage. Twenty-four New Zealand white rabbits were randomly divided into A, B, and C groups. Engineered cartilage was transplanted into cartilage defect position of rabbits in group A, group B obtained ACMs, and group C did not receive any transplants. The rabbits were sacrificed in week 12. The restored tissue was evaluated using macroscopy, histology, immunohistochemistry, and transmission electron microscopy (TEM). In the tissue-engineered cartilage group (group A), articular cartilage defects of the rabbits were filled with chondrocyte-like tissue with smooth surface. Immunohistochemistry showed type II-collagen expression and Alcian blue staining was positive. TEM showed chondrocytes in the recesses, with plenty of secretary matrix particles. In the scaffold group (group B), the defect was filled with fibrous tissue. No repaired tissue was found in the blank group (group C). Tissue-engineered cartilage using ACM seeded with ADSCs can help repair articular cartilage defects in rabbits.

Regenerating Cartilages by Engineered ASCs: Prolonged TGF-β3/BMP-6 Expression Improved Articular Cartilage Formation and Restored Zonal Structure

Adipose-derived stem cells (ASCs) hold promise for cartilage regeneration but their chondrogenesis potential is inferior. Here, we used a baculovirus (BV) system that exploited FLPo/Frt-mediated transgene recombination and episomal minicircle formation to genetically engineer rabbit ASCs (rASCs). The BV system conferred prolonged and robust TGF-β3/BMP-6 expression in rASCs cultured in porous scaffolds, which critically augmented rASCs chondrogenesis and suppressed osteogenesis/hypertrophy, leading to the formation of cartilaginous constructs with improved maturity and mechanical properties in 2-week culture. Twelve weeks after implantation into full-thickness articular cartilage defects in rabbits, these engineered constructs regenerated neocartilages that resembled native hyaline cartilages in cell morphology, matrix composition and mechanical properties. The neocartilages also displayed cartilage-specific zonal structures without signs of hypertrophy and degeneration, and eventually integrated with host cartilages. In contrast, rASCs that transiently expressed TGF-β3/BMP-6 underwent osteogenesis/hypertrophy and resulted in the formation of inferior cartilaginous constructs, which after implantation regenerated fibrocartilages. These data underscored the crucial role of TGF-β3/BMP-6 expression level and duration in rASCs in the cell differentiation, constructs properties and in vivo repair. The BV-engineered rASCs that persistently express TGF-β3/BMP-6 improved the chondrogenesis, in vitro cartilaginous constructs production and in vivo hyaline cartilage regeneration, thus representing a remarkable advance in cartilage engineering.

Erratum to: MRI and CT evaluations of an invented bioglue in experimentally induced articular cartilage defects in rabbits

Articular cartilage defect is a condition leading to osteoarthritis of the joints if they remain unhealed or untreated. Some available surgical adhesives are used to adhere the wandering cartilaginous particle and avoid further joint damage. Healing as well as adhering properties of different substances has always been a topic of concern. Magnetic resonance imaging (MRI) and computed tomography (CT) are used to diagnose the condition. This is an effort to evaluate the healing and adhering properties of a newly invented bioglue, both with MRI and CT. Sixty adult, Dutch, male rabbits used for this study were divided into five equal groups (A–E). The groups were A: (a harvested graft was adhered to 4-mm diameter defects), B: (same as group A with 6-mm diameter defect), C: (4- and 6-mm defects were made in either knee or the graft sutured), D: (only defects were created and remained intact), and E: (defects were created and filled with bioglue). The groups were imaged 30 and 60 days postoperation. CT results showed that there was no significant difference in spur formation between groups, while focal osteopenia was higher in groups A, B, C (30 days), and D (30 days). Sclerosis was lower in group E than other groups. MRI showed subchondral signal change and joint effusion to be lower in group E than other groups. The invented bioglue in the present work reduced OA signs on CT and MRI and had no side effects.

MRI and CT evaluations of an invented bioglue in experimentally induced articular cartilage defects in rabbits

MRI and CT evaluations of an invented bioglue in experimentally induced articular cartilage defects in rabbits

Exogenous bFGF promotes articular cartilage repair via up-regulation of multiple growth factors

To investigate the roles of exogenous basic fibroblast growth factor (bFGF) on the repair of full-thickness articular cartilage defects in rabbits. In the present study, a double-layered collagen membrane sandwiched with bFGF-loaded-nanoparticles between a dense layer and a loose layerwas implanted into full-thickness articular cartilage defects in rabbits. By grafting the membrane in a different direction, the dense layer or the loose layer facing the surface of the subchondral bone, the effects of the released bFGF on the defects and the profiles of nine growth factors (GFs) in synovial fluid (SF) were investigated using histological methods and antibody arrays, respectively. In the group with the loose layer facing the surface of the subchondral bone, fast release of bFGF was observed, and early high levels of endogenous transforming growth factor-β2 (TGF-β2), vascular endothelial growth factor (VEGF), bFGF, bone morphogenetic protein 2 (BMP-2), BMP-3, and BMP-4 in SF were detected by antibody arrays, especially on day 3. Chondrocyte-like cells were also observed in this group at an early stage. As a result, this group showed better levels of repair, as compared to the other groups in which low GF levels were detected at an early stage, and chondrocyte-like cells appeared much later. Our study suggests that exogenous bFGF promotes articular cartilage repair by up-regulating the levels of multiple GFs, but administration at an early stage is required.

Cartilage repair of experimentally 11 induced osteochondral defects in New Zealand White rabbits

Articular cartilage has a limited capacity for self-repair in adult humans, and methods used to stimulate regeneration often result in re-growth of fibrous cartilage, which has lower durability. No current treatment option can provide complete repair. The possibility of growth factor delivery into the joint for cartilage regeneration after injury would be an attractive treatment option. A full thickness osteochondral defect of 4 mm in diameter and 2 mm deep was created by mechanical drilling in the medial femoral condyle in 20 female adult New Zealand White rabbits. In an attempt to improve regeneration a hyaluronic hydrogel system, with or without bone morphogenetic protein-2 (BMP-2) was delivered intraarticularly. The contralateral joint defect was treated with saline as control. Throughout the study, rabbits were clinically examined and after 12 (n = 6) or 24 (n = 9) weeks, the rabbits were euthanized and the joints evaluated by histology. The defects healed with fibrocartilage like tissue, and the filling of the defects ranged from less than 25% to complete. The healing of the defects varied both inter- and intra-group wise. Treatment with hyaluronan gel with or without BMP-2 had no effect on cartilage regeneration compared with controls. Instead, severe ectopic bone formation was found in seven joints treated with BMP-2. In conclusion, the present study shows that neither treatment with hyaluronic gel alone, nor in combination with BMP-2, improves the healing of an induced cartilage defect in rabbits. It further shows that BMP-2 can induce ectopic bone formation, which severely affects the functionality of the joint.

Combined Effects of Connective Tissue Growth Factor&amp;#45;modified Bone Marrow&amp;#45;Derived Mesenchymal Stem Cells and NaOH&amp;#45;treated PLGA Scaffolds on Repair of Articular Cartilage Defect in Rabbits

Combined Effects of Connective Tissue Growth Factor&amp;#45;modified Bone Marrow&amp;#45;Derived Mesenchymal Stem Cells and NaOH&amp;#45;treated PLGA Scaffolds on Repair of Articular Cartilage Defect in Rabbits

COMPARING EXTRACORPOREAL SHOCK WAVE AND HYALURONIC ACID ON RABBIT CARTILAGE DEFECT MODEL

To compare the efficiency of extracorporeal shock wave (ESW) treatment with hyaluronic acid (HA) viscosupplementation in an experimental rabbit cartilage defect model. Materials and methods: A total of 24 New Zealand rabbits were randomly divided into 4 groups: HA, ESW, ESW + HA, and control. Chondral defects were created in the left knees of the rabbits. HA viscosupplementation was performed on the HA and ESW + HA groups, and after 24 h, 0.16 mJ/mm2 ESW was performed on the ESW and ESW + HA groups. After an 8-week follow-up, the rabbits were sacrificed and histopathological examination of the defects was carried out. In addition, immunohistochemistry was performed by the avidin-biotin peroxidase method using vascular endothelial growth factor (VEGF), transforming growth factor beta 1 (TGF-beta 1), and type II collagen antibodies, and the results were evaluated semiquantitatively. Results: There was a significant difference between the control group and the ESW group in terms of Pineda score and type II collagen expression; between the control group and the HA group in terms of Pineda score, VEGF expression, type II collagen expression, and TGF-beta 1 expression; and between the control group and the ESW + HA group in terms of Pineda score, VEGF expression, type II collagen expression, and TGF-beta 1 expression. Conclusion: The results show that both treatment methods have positive therapeutic effects on the articular cartilage defect model in terms of the parameters studied.

Transplantation of Autologous Chondrocytes Seeded on a Fibrin/Hyaluronan Composite Gel Into Tracheal Cartilage Defects in Rabbits: Preliminary Results

Reconstruction of tracheal defects is one of the most difficult procedures in head and neck surgery. To date, various reconstructing techniques have been used with no consensus on the best approach. This study investigated the feasibility of using a fibrin/hyaluronic acid (HA) composite gel with autologous chondrocytes for tracheal reconstruction. Chondrocytes from autologous rabbit auricular cartilages were expanded and seeded into a culture dish at high density to form stable tracheal cartilages mechanically using a fibrin/HA composite gel. A 1-cm long by 0.5-cm wide defect was created by a scalpel on the cervical tracheae of six rabbits. Tissue-engineered cartilages using fibrin/HA composite were trimmed and fixed to the defect boundaries with tissuecol. Postoperatively, the site was evaluated endoscopically, histologically, radiologically, and functionally. None of the six rabbits showed signs of respiratory distress. Postoperatively, in all cases, rigid telescopic examination showed that the implanted scaffolds were completely covered with regenerated mucosa without granulation or stenosis. Histologically, the grafts showed no signs of inflammatory reaction and were covered with ciliated epithelium. Even when grafts were broken and migrated from their original insertion site, the implanted cartilages were well preserved. However, the grafts did show signs of mechanical failure at the implantation site. The beat frequency of ciliated epithelium on implants was very similar to that of normal respiratory mucosa. In conclusion, implants with autologous chondrocytes cultured with fibrin/HA showed good tracheal luminal contour, functional epithelial regeneration, and preservation of neocartilage without inflammation but lacked adequate mechanical stability.

Using Cartilage Extracellular Matrix (CECM) Membrane to Enhance the Reparability of the Bone Marrow Stimulation Technique for Articular Cartilage Defect in Canine Model

AbstractBone marrow stimulation techniques (BSTs) are widely used in clinics to treat cartilage defects, but yet have a critical limitation from the loss of blood clots. In this work, a novel cartilage extracellular matrix (CECM) membrane is developed to protect blood clots after BSTs. The CECM membrane was made of ECM fabricated naturally by cultured porcine chondrocytes, and then decellularized and multi‐layered to confer optimal mechanical strength. Highly compatible with cells, the CECM membrane did not show any cytotoxicity or immune responses in vivo. The CECM membrane was very thin (30–60 μm thick) and bendable, but had good tensile strength (85.64 N), suitable for protecting blood clots from leakage in rabbit cartilage defect. Moreover, the CECM membrane showed low but enough diffusion coefficient to allow delivery of small proteins in synovial fluid into the repaired tissue. In a beagle model, covering the cartilage defect with the CECM membrane after BST generated more hyaline cartilage‐like tissues than the BST alone in histology and chemical analyses at 18 weeks. Its ICRS score was approximately 2.5 times higher than that of the BST alone. Therefore, the CECM membrane is proposed as a useful tool that can improve the outcome of BSTs to treat cartilage defects.

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.