Rabbit Chondrocytes Research Articles

ALB–PRF facilitates chondrogenesis by promoting chondrocytes migration, proliferation and differentiation

Cartilage injury is common in orthopedics and cartilage tissue engineering provides a therapeutic direction for cartilage regeneration. Albumin (ALB)–platelet-rich fibrin (PRF) is speculated to be an ideal natural scaffold material for cartilage tissue engineering theoretically as a product derived from human venous blood. Through in vitro and in vivo experiments, it was demonstrated that ALB–PRF displayed porous structure and slowly released growth factors (TGF-β1, PDGF-AA, PDGF-AB, PDGF-BB, EGF, IGF-1 and VEGF), ALB–PRF conditioned media promoted proliferation, migration, adhesion, phenotype maintenance and extracellular matrix secretion of rabbit chondrocytes. Moreover, ALB–PRF facilitated chondrogenesis in vivo, the regenerative cartilage formed by ALB–PRF/chondrocytes was histologically similar to that of natural knee joint cartilage, the regenerative cartilage expressed cartilage differentiation marker (SOX9, ACAN and COL II), and proliferation marker PCNA and secreted abundant glycosaminoglycans (GAGs) in extracellular matrix. In conclusion, ALB–PRF promoted the migration, proliferation and phenotype maintenance of chondrocytes in vitro. Its loose, porous structure and rich growth factors contained enhanced cell adhesion and growing into the materials. ALB–PRF facilitated chondrogenesis of chondrocytes in vivo.

Promotion and Mechanism of Acupotomy on Chondrocyte Autophagy in Knee Osteoarthritis Rabbits.

To explore the effect of acupotomy intervention on autophagy of chondrocytes in rabbits with knee osteoarthritis (KOA), and to determine the possible mechanisms of acupotomy to alleviate cartilage degeneration. The modified Videman method was used to construct a KOA rabbit model. After modeling, 40 rabbits were randomly divided into 4 groups by a random number table: control; KOA (model); KOA + acupotomy (acupotomy), and KOA + sham acupotomy (sham), 10 in each group. After a 3-week treatment course, the knee joint activity was determined by the modified Lequesne MG index. Hematoxylin-eosin staining staining was used to examine the morphological changes of chondrocytes. Autophagy of chondrocytes was observed by transmission electron microscopy. The surface morphology of cartilage tissue was observed by scanning electron microscope. The mRNA and protein levels of AMP kinase/mammalian target of rapamycin/Unc-51 (AMPK/mTOR/ULK1) signal pathway key proteins, autophagy-related factor Beclin-1 and microtubule-associated protein 1A/1B light chain 3 (LC3) in rabbit knee cartilage were assessed by real-time fluorescence quantitative polymerase chain reaction and Western blot, respectively. The modified Lequesne MG score of acupotomy group was significantly lower than that of model group (P<0.05). Pathological results showed that chondrocyte autophagy decreased and cartilage surface was rough in the model group, which recovered after acupotomy treatment. The mRNA expressions of AMPK, ULK1, Beclin-1 and the protein levels of p-AMPK, p-ULK1, Beclin-1, and LC3 II/LC3 I were decreased in the model group, while the mRNA and protein expressions of mTOR were increased (P<0.01). However, acupotomy treatment reversed these abnormal changes (P<0.05). Acupotomy could effectively up-regulate the expressions of AMPK, ULK1 and Beclin1, reduce the expression of mTOR, promote autophagy, and alleviate joint degeneration. Acupotomy is a promising complementary and alternative therapy for KOA.

Cobalt-containing calcium silicate nanowires incorporated scaffolds for the repair of osteochondral defect induced by chondrosarcoma

Considering the difficulty in the treatment of chondrosarcoma in clinic, multifunctional composite hydrogel scaffolds were designed with excellent photothermal ability for the regeneration of damaged bone and cartilage tissue. The chitosan solution/polyvinyl alcohol (CP) hydrogels with different contents of cobalt doped calcium silicate (Co-CSH) nanowires were prepared via 3D printing method. Attributing to the excellent photothermal performance of Co-CSH nanowires, the average survival rate of human chondrosarcoma cells in the CP-5Co-13.4 % and CP-5Co-16.2 % scaffolds with near infrared laser irradiation was about 10.5 % and 9.9 %, respectively. At the same time, the prepared composite hydrogel scaffolds possessed satisfactory biocompatibility and could support the adhesion and spread of rabbit bone mesenchymal stem cells (rBMSCs) and rabbit chondrocytes in the hydrogel scaffolds, and further promoted the formation of new bone and cartilage tissue in vivo, on account of the stimulation effect of released bioactive ions. Therefore, the prepared composite hydrogel scaffolds is expected to provide a new therapeutic strategy for the postoperative adjuvant treatment of chondrosarcoma.

The potential of an electrospun poly (3-hydroxybutyrate)/poly (ethylene glycol) blend fibrous scaffold for cartilage tissue engineering

Poly (3-hydroxybutyrate) and poly (ethylene glycol) are frequently used as materials for designing scaffolds in tissue engineering. This work aimed the production of P3HB-PEG scaffolds in different weight ratio of PEG using electrospinning and characterized. Samples also were examined for rabbit chondrocyte cell assay. 5 wt% of PEG decreased the nanofiber diameter with more uniformity and enhanced hydrophilicity. The biodegradation rate increased while the mechanical features tended to decrease. In vitro tests showed good chondrocyte cell viability and adhesion. These results manifested that electrospun the P3HB-PEG scaffolds could enhance cartilage regeneration, showing their marvelous prospect as scaffolds for cartilage tissue engineering.

Electroacupuncture improves articular microcirculation and attenuates cartilage hypoxia in a male rabbit model of knee osteoarthritis

Background and aimHypoxia of the cartilage has been considered as a potential pathogenic factor in knee osteoarthritis (KOA). Studies have shown that impaired blood perfusion of joint leads to cartilage hypoxia. Electroacupuncture (EA) has proven effects on pain relief and improving microcirculation. This study aimed to explore the effect of EA on articular microcirculation and cartilage anoxic and the underlying mechanisms. ProceduresVideman's method was used for 6 weeks to establish the KOA model. EA intervention was performed in four points around the knee for 3 weeks after KOA modeling. The Lequesne MG score was used to assess ethology. We recorded the oxygen tension of synovial fluid and the synovial microcirculation in vivo. HE-staining was used to assess cartilage morphology, and immunohistochemistry (IHC), Western blotting, and RT-PCR were used to assess expression of the major glycolytic enzymes glucosetransporter1 (GLUT1), pyruvate kinase M2(PKM2), and lactate dehydrogenase A (LDHA). Enzyme-linked immunosorbent assay (Elisa) was used to detect lactate content. Results and conclusionThere was a significant decrease in Lequesne MG score and improvement in Mankin score after EA intervention (P < 0.01), a significant increase in synovial microcirculation (P < 0.05) and synovial fluid oxygen tension (P < 0.01), and there was significant decrease in the expression of GLUT1, PKM2 and LDHA (P < 0.01) and lactate (P < 0.05). This study suggested that EA ameliorate cartilage hypoxia and regulate glycolytic metabolism in chondrocytes in KOA model rabbits by improving articular microcirculation and oxygen tension.

Quantitative evaluation of warm acupuncture-moxibustion in improvement of cartilage damage in rabbits with early knee osteoarthritis based on MR T2 mapping.

To observe the application value of MR T2 mapping for evaluating the effect of warm acupuncture-moxibustion on articular cartilage degeneration, and to observe the relationship between T2 value and expression of matrix metalloproteinases (MMP)-1 and MMP-13 of chondrocytes in rabbits with early knee osteoarthritis (KOA). Thirty male New Zealand rabbits were randomly divided into blank control, KOA model and warm acupuncture-moxibustion groups, with 10 rabbits in each group. The early KOA model was established by right hind limb tubular plaster extension fixation method for 2 weeks. The rabbits of the warm acupuncture-moxibustion group received warm acupuncture-moxibustion stimulation at "Heding"(EX-LE2), "Neixiyan"(EX-LE4), "Waixiyan" (EX-LE5) and"Zusanli"(ST36) on the right hind limb for 15 min, once a day for 2 weeks. After intervention, MR T2 mapping of the right knee joint was performed in each group. The H.E. staining was used to evaluate the histopathological changes of cartilage, followed by giving a score according to the standards of Mankin scoring. The TUNEL method was used to analyze the apoptosis state of chondrocytes, and the positive expressions of MMP-1 and MMP-13 in the articular cartilage were detected by immunohistochemical staining. Compared with the blank control group, the Mankin score, chondrocyte apoptosis index, T2 value and the positive expressions of MMP-1 and MMP-13 in the cartilage tissue were significantly increased in the model group (P<0.01). Compared with the model group, the Mankin score, chondrocyte apoptosis index, T2 value and the positive expressions of MMP-1 and MMP-13 in the cartilage tissue were markedly decreased in the warm acupuncture-moxibustion group (P<0.01). The T2 value was positively correlated with the expression levels of MMP-1 and MMP-13 (P<0.01). H.E. staining showed disordered arrangement of chondrocytes and thinner cartilage layer in the model group, and a clear and relative ordered arrangement of chondrocyte in the warm acupuncture-moxibustion group. Warm acupuncture-moxibustion can reduce the T2 value of articular cartilage in early KOA rabbits, which is positively correlated with the decreased expression of MMP-1 and MMP-13 in the extracellular matrix of cartilage. The MR T2 mapping has certain value in evaluating the effect of warm acupuncture-moxibustion on KOA rabbits with early cartilage degeneration.

3D-Printed Composite Bioceramic Scaffolds for Bone and Cartilage Integrated Regeneration.

Osteoarthritis may result in both cartilage and subchondral bone damage. It is a significant challenge to simultaneously repair cartilage due to the distinct biological properties between cartilage and bone. Here, strontium copper tetrasilicate/β-tricalcium phosphate (Wesselsite[SrCuSi4O10]/Ca3(PO4)2, WES-TCP) composite scaffolds with different WES contents (1, 2, and 4 wt %) were fabricated via a three-dimensional (3D) printing method for the osteochondral regeneration. The physicochemical properties and biological activities of the scaffolds were systematically investigated. 2WES-TCP (WES-TCP with 2 wt % WES) composite scaffolds not only improved the compressive strength but also enhanced the proliferation of both rabbit bone mesenchymal stem cells (rBMSCs) and chondrocytes, as well as their differentiation. The in vivo study further confirmed that WES-TCP scaffolds significantly promoted the regeneration of both bone and cartilage tissue in rabbit osteochondral defects compared with pure TCP scaffolds owing to the sustained and controlled release of bioactive ions (Si, Cu, and Sr) from bioactive scaffolds. These results show that 3D-printed WES-TCP scaffolds with bilineage bioactivities take full advantage of the bifunctional properties of bioceramics to reconstruct the complex osteochondral interface, which broadens the approach to engineering therapeutic platforms for biomedical applications.

A bioengineered trachea-like structure improves survival in a rabbit tracheal defect model.

A practical strategy for engineering a trachea-like structure that could be used to repair or replace a damaged or injured trachea is an unmet need. Here, we fabricated bioengineered cartilage (BC) rings from three-dimensionally printed fibers of poly(ɛ-caprolactone) (PCL) and rabbit chondrocytes. The extracellular matrix (ECM) secreted by the chondrocytes combined with the PCL fibers formed a "concrete-rebar structure," with ECM deposited along the PCL fibers, forming a grid similar to that of native cartilage. PCL fiber-hydrogel rings were then fabricated and alternately stacked with BC rings on silicone tubes. This trachea-like structure underwent vascularization after heterotopic transplantation into rabbits for 4 weeks. The vascularized bioengineered trachea-like structure was then orthotopically transplanted by end-to-end anastomosis to native rabbit trachea after a segment of trachea had been resected. The bioengineered trachea-like structure displayed mechanical properties similar to native rabbit trachea and transmural angiogenesis between the rings. The 8-week survival rate in transplanted rabbits was 83.3%, and the respiratory rate of these animals was similar to preoperative levels. This bioengineered trachea-like structure may have potential for treating tracheal stenosis and other tracheal injuries.

Injectable gelatin/glucosamine cryogel microbeads as scaffolds for chondrocyte delivery in cartilage tissue engineering

In this study, we fabricate squeezable cryogel microbeads as injectable scaffolds for minimum invasive delivery of chondrocytes for cartilage tissue engineering applications. The microbeads with different glucosamine concentrations were prepared by combining the water-in-oil emulsion and cryogelation through crosslinking of gelatin with glutaraldehyde in the presence of glucosamine. The physicochemical characterization results show the successful preparation of cryogel microbeads with uniform shape and size, high porosity, large pore size, high water uptake capacity, and good injectability. In vitro analysis indicates proliferation, migration, and differentiated phenotype of rabbit chondrocytes in the cryogel scaffolds. The seeded chondrocytes in the cryogel scaffold can be delivered by injecting through an 18G needle to fully retain the cell viability. Furthermore, the incorporation of glucosamine in the cryogel promoted the differentiated phenotype of chondrocytes in a dose-dependent manner, from cartilage-specific gene expression and protein production. The in vivo study by injecting the cryogel microbeads into the subcutaneous pockets of nude mice indicates good retention ability as well as good biocompatibility and suitable biodegradability of the cryogel scaffold. Furthermore, the injected chondrocyte/cryogel microbead constructs can form ectopic functional neocartilage tissues following subcutaneous implantation in 21 days, as evidenced by histological and immunohistochemical analysis.

Electroacupuncture Exerts Chondroprotective Effect in Knee Osteoarthritis of Rabbits Through the Mitophagy Pathway.

Mitochondrial dysfunction of chondrocytes has become an area of focus in Knee Osteoarthritis (KOA) in recent years. Activation of mitophagy could promote the survival of chondrocytes and alleviate cartilage degeneration. The aim of this study was to explore whether mitophagy was involved in the cartilage protection of KOA rabbits after electroacupuncture (EA) intervention. The rabbits were divided into 3 groups, Control group, KOA group, EA group, with 6 rabbits in each group. KOA model rabbits were established by modified Videman's extended immobilization method for 6 weeks and randomly divided into KOA group and EA group. The rabbits in EA group were treated every other day for 3 weeks. The degree of cartilage degeneration was detected by Safranine O-Fast Green staining and immunofluorescence. The morphological changes of chondrocytes mitochondria were detected by transmission electron microscope. ATP concentration in cartilage was measured by ATP Assay Kit. The changes of Pink1-Parkin signal pathway were detected by immunofluorescence, Western blot, and Real-time PCR. The morphology showed that EA could reduce the degeneration of KOA cartilage and increase the distribution of collagen II. We also found that EA could activate mitophagy in KOA rabbit chondrocytes to remove damaged mitochondria and restore mitochondrial homeostasis, which was manifested as increasing the expression of LC3 II/I, promoting the colocalization of TOM20 and LC3B, reducing the accumulation of mitochondrial markers outer mitochondrial membrane 20 (TOM20) and inner mitochondrial membrane 23 (TIM23), and increasing ATP production in chondrocytes. This regulation might be achieved by upregulating the Pink1-Parkin signal pathway. EA may play a role in protecting KOA cartilage by activating mitophagy mediated through Pink1-Parkin pathway.

Heterogeneous Cells as well as Adipose-Derived Stromal Cells in Stromal Vascular Fraction Contribute to Enhance Anabolic and Inhibit Catabolic Factors in Osteoarthritis.

The stromal-vascular fraction (SVF), comprising heterogeneous cell populations and adipose-derived stromal cells (ADSCs), has therapeutic potential against osteoarthritis (OA); however, the underlying mechanism remains elusive. This study aimed to investigate the therapeutic effects of heterogeneous cells in rabbit SVF on rabbit chondrocytes. Rabbit SVF and ADSCs were autografted into knees at OA onset. The SVF (1 × 105) and low-dose ADSCs (lADSC; 1 × 104) groups adjusted for their stromal cell content were compared. Animals were euthanized 8 and 12 weeks after OA onset for macroscopic and histological analyses of OA progression and synovitis. Immunohistochemical and real-time polymerase chain reaction assessments were conducted. In vitro, immune-fluorescent double staining was performed for SVF to stain macrophages with F4/80, CD86(M1), and CD163(M2). OA progression was markedly suppressed, and synovitis was reduced in the SVF groups (OARSI histological score 8W: 6.8 ± 0.75 vs. 3.8 ± 0.75, p = 0.001; 12W: 8.8 ± 0.4 vs. 5.4 ± 0.49, p = 0.0002). The SVF groups had higher expression of collagen II and SOX9 in cartilage and TGF-β and IL-10 in the synovium, lower expression of MMP-13, and lower macrophage M1/M2 ratio than the lADSC groups. Immunofluorescent double staining revealed a markedly higher number of M2 than that of M1 macrophages in the SVF. The therapeutic effects of SVF on chondrocytes were superior than those of lADSCs, with enhanced anabolic and inhibited catabolic factors. Heterogeneous cells, mainly M2 macrophages in the SVF, enhanced growth factor secretion and chondrocyte-protective cytokines, thus benefiting chondrocytes and knee joint homeostasis. Overall, the SVF is a safe, relatively simple, and a useful treatment option for OA.

Micronutrient optimization for tissue engineered articular cartilage production of type II collagen.

Tissue Engineering of cartilage has been hampered by the inability of engineered tissue to express native levels of type II collagen in vitro. Inadequate levels of type II collagen are, in part, due to a failure to recapitulate the physiological environment in culture. In this study, we engineered primary rabbit chondrocytes to express a secreted reporter, Gaussia Luciferase, driven by the type II collagen promoter, and applied a Design of Experiments approach to assess chondrogenic differentiation in micronutrient-supplemented medium. Using a Response Surface Model, 240 combinations of micronutrients absent in standard chondrogenic differentiation medium, were screened and assessed for type II collagen promoter-driven Gaussia luciferase expression. While the target of this study was to establish a combination of all micronutrients, alpha-linolenic acid, copper, cobalt, chromium, manganese, molybdenum, vitamins A, E, D and B7 were all found to have a significant effect on type II collagen promoter activity. Five conditions containing all micronutrients predicted to produce the greatest luciferase expression were selected for further study. Validation of these conditions in 3D aggregates identified an optimal condition for type II collagen promoter activity. Engineered cartilage grown in this condition, showed a 170% increase in type II collagen expression (Day 22 Luminescence) and in Young's tensile modulus compared to engineered cartilage in basal media alone.Collagen cross-linking analysis confirmed formation of type II-type II collagen and type II-type IX collagen cross-linked heteropolymeric fibrils, characteristic of mature native cartilage. Combining a Design of Experiments approach and secreted reporter cells in 3D aggregate culture enabled a high-throughput platform that can be used to identify more optimal physiological culture parameters for chondrogenesis.

MicroRNA-146a-5p alleviates the pathogenesis of osteoarthritis by inhibiting SDF-1/CXCR4-induced chondrocyte autophagy.

SDF-1/CXCR4 signaling promotes osteoarthritis (OA) development. CXCR4 is a potential target of miR-146a-5p. This study investigated the therapeutic role and the underlying mechanism of miR-146a-5p in OA. Human primary chondrocytes C28/I2 were stimulated with SDF-1. Cell viability and LDH release were examined. Chondrocyte autophagy was assessed using Western blot analysis, ptfLC3 transfection, and transmission electron microscopy. MiR-146a-5p mimics were transfected into C28/I2 cells to investigate the role of miR-146a-5p in SDF-1/CXCR4-induced autophagy of chondrocytes. An SDF-1-induced rabbit OA model was established to investigate the therapeutic role of miR-146a-5p in OA. Histological staining was performed to observe the morphology of osteochondral tissue. SDF-1/CXCR4 signaling promoted autophagy in C28/I2 cells, as demonstrated by increased LC3-II protein expression and autophagic flux induced by SDF-1. SDF-1 treatment significantly inhibited cell proliferation while promoting necrosis and autophagosome formation in C28/I2 cells. In the presence of SDF-1, miR-146a-5p overexpression in C28/I2 cells suppressed CXCR4 mRNA expression, LC3-II and Beclin-1 protein expression, LDH release, and autophagic flux. In addition, SDF-1 increased the autophagy of chondrocytes in rabbits and promoted the development of OA. Compared with the negative control, miR-146a-5p significantly reduced the morphological abnormalities of the rabbit cartilage that were induced by SDF-1, as well as the number of LC3-II-positive cells, protein expression of LC3-II and Beclin 1, and mRNA expression of CXCR4 in osteochondral tissue. These effects were reversed by the autophagy agonist rapamycin. SDF-1/CXCR4 promotes OA development by enhancing chondrocyte autophagy. MicroRNA-146a-5p may alleviate OA by suppressing CXCR4 mRNA expression and SDF-1/CXCR4-induced chondrocyte autophagy.

Mechanism of the inhibitory effect of acupotomy on chondrocyte apoptosis in KOA rabbits explored via proteomics 运用蛋白质组学技术探讨针刀抗KOA兔软骨细胞凋亡的作用机制

ObjectiveTo elucidate the mechanism underlying the inhibitory effect of acupotomy on chondrocyte apoptosis in rabbits with knee osteoarthritis (KOA) through screening, analysis, and verification of apoptosis-related differentially expressed proteins via proteomics. MethodsThirty New Zealand white rabbits were randomly divided into the normal, model, and acupotomy groups, with 10 rabbits in each group. The Vidman method was used to prepare KOA models in the model and acupotomy groups. In the acupotomy group, acupotomy was performed at the midpoints of the patellar ligament and medial and lateral collateral ligaments on the left knees once a week for three weeks. Rabbit articular cartilage protein was quantified in each group, and the proteins with differential expression were profiled via proteomics. The apoptosis-related proteins were further screened, and differentially expressed proteins common among the normal, model, and acupotomy groups were collected for cluster analysis. Pathological changes in chondrocytes were observed via HE staining, and chondrocyte apoptosis was observed under an electron microscope. Quantitative real-time PCR (RT-PCR) and western blot were performed to determine the mRNA and protein expression levels, respectively, of the common apoptosis-related proteins in the three groups. ResultsWestern blot and RT-PCR showed that the protein and mRNA expression levels of TXN, CAP1 and FABP3 were lower (all P < 0.05), whereas that of LTF, SCIN and IL-10 were higher (all P < 0.01) in the acupotomy group than that in the model group. ConclusionThe antiapoptotic effect of acupotomy on chondrocytes in KOA rabbits may be achieved by modulating the protein and mRNA expression of differentially expressed apoptosis-related proteins (TXN, CAP1, FABP3, LTS, SCIN, and IL-10).

Research of diclofenac sodium-loaded gelatin scaffold with anti-inflammatory activity for promoting in vivo cartilage regeneration

To develop a diclofenac sodium-loaded gelatin scaffold with anti-inflammatory activity and provide a new avenue for alleviating the inflammatory response and enhancing cartilage regeneration in vivo. Diclofenac sodium was homogeneously mixed with gelatin to prepare a diclofenac sodium-loaded porous gelatin scaffold by freeze-drying method as the experimental group, and a pristine porous gelatin scaffold was served as a control group. The general morphology of the scaffold was observed, the pore size of the scaffold was measured by scanning electron microscopy, the porosity of the scaffold was calculated by drainage method, the loading of diclofenac sodium into the gelatin scaffold was detected by fourier transform infrared spectrometer and X-ray diffraction examinations, and the release kinetics of diclofenac sodium from gelatin scaffold was tested using an in vitro release assay. The two scaffolds were co-cultured with lipopolysaccharide-predisposed RAW264.7 in vitro, and the expressions of interleukin 1β (IL-1β) and tumor necrosis factor α (TNF-α) were detected by reverse transcription polymerase chain reaction (RT-PCR), enzyme-linked immuno sorbent assay, and Western blot, to detect the in vitro anti-inflammatory effect of the drug-loaded scaffold. Thereafter, the second generation chondrocytes of New Zealand white rabbits were inoculated on the two groups of scaffolds for in vitro culture, and the cytocompatibility of the scaffold was tested by live/dead staining and cell counting kit 8 assay, the feasibility of in vitro cartilage regeneration of the scaffold was evaluated via gross observation, HE staining, Safranin-O staining, and immunohistochemical collagen type Ⅱ staining, as well as biochemical quantitative analyses. Finally, the two groups of chondrocyte-scaffolds were implanted subcutaneously into New Zealand white rabbits, and after 4 weeks, the general observation, HE staining, safranin O staining, immunohistochemical collagen type Ⅱ staining, and biochemical quantitative analyses were performed to verify the cartilage regeneration in vivo, and the expression of inflammation-related genes CD3 and CD68 was detected by RT-PCR to comprehensively evaluate the anti-inflammatory performance of the scaffolds in vivo. The two scaffolds exhibited similar gross, microporous structure, pore size, and porosity, showing no significant difference (P>0.05). Diclofenac sodium was successfully loaded into gelatin scaffold. Data from in vitro anti-inflammatory assay suggested that diclofenac sodium-loaded gelatin scaffold showed alleviated gene and protein expressions of IL-1β and TNF-α when compared with gelatin scaffold (P<0.05). The evaluation of cartilage regeneration in vitro showed that the number of living cells increased significantly with the extension of culture time, and there was no significant difference between the two groups at each time point (P>0.05). White cartilage-like tissue was regenerated from the scaffolds in both groups, histological observation showed typical cartilage lacuna structure and specific cartilage extracellular matrix secretion. There was no significant difference in the content of cartilage-specific glycosaminoglycan (GAG) and collagen type Ⅱ between the two groups (P>0.05). In vivo experiments showed that the samples in the experimental group had porcelain white cartilage like morphology, histologic staining showed obvious cartilage lacuna structure and cartilage specific extracellular matrix, the contents of GAG and collagen type Ⅱ were significantly higher than those in the control group, and the protein and mRNA expressions of CD3 and CD68 were significantly lower than those in the control group, with significant differences (P<0.05). The diclofenac sodium-loaded gelatin scaffold presents suitable pore size, porosity, and cytocompatibility, as well as exhibited satisfactory anti-inflammatory ability, providing a reliable scheme for alleviating the inflammatory reaction of regenerated cartilage tissue after in vivo implantation and promoting cartilage regeneration in vivo.

Optimization of 3D autologous chondrocyte-seeded polyglycolic acid scaffolds to mimic human ear cartilage.

Auricular reconstruction in children with microtia is one of the more complex procedures in plastic surgery. Obtaining sufficient native material to build an ear requires harvesting large fragments of rib cartilage in children. Herein, we investigated how to optimize autologous chondrocyte isolation, expansion and re-implantation using polyglycolic acid (PGA) scaffolds for generating enough cartilage to recapitulate a whole ear starting from a small ear biopsy. Ear chondrocytes isolated from human microtia subjects grew slower than microtia rib or healthy ear chondrocytes and displayed a phenotypic shift due to the passage number. Rabbit ear chondrocytes co-cultured with mesenchymal stem cells (MSC) at a 50 : 50 ratio recapitulated the cartilage biological properties in vitro. However, PGA scaffolds with different proportions of rabbit chondrocytes and MSC did not grow substantially in two months when subcutaneously implanted in immunosuppressed mice. In contrast, rabbit chondrocyte-seeded PGA scaffolds implanted in immunocompetent rabbits formed a cartilage 10 times larger than the original PGA scaffold. This cartilage mimicked the biofunctional and mechanical properties of an ear cartilage. These results indicate that autologous chondrocyte-seeded PGA scaffolds fabricated following our optimized procedure have immense potential as a solution for obtaining enough cartilage for auricular reconstruction and opens new avenues to redefine autologous cartilage replacement.

Anti-Osteoarthritic Effects of Cartilage-Derived Extracellular Matrix in a Rat Osteoarthritis Model.

The extracellular matrix (ECM) has many functions, such as segregating tissues, providing support, and regulating intercellular communication. Cartilage-derived ECM (CECM) can be prepared via consecutive processes of chemical decellularization and enzyme treatment. The purpose of this study was to improve and treat osteoarthritis (OA) using porcine knee articular CECM. We assessed the rheological characteristics and pH of CECM solutions. Furthermore, we determined the effects of CECM on cell proliferation and cytotoxicity in the chondrocytes of New Zealand rabbits. The inhibitory effect of CECM on tumor necrosis factor (TNF)-α-induced cellular apoptosis was assessed using New Zealand rabbit chondrocytes and human synoviocytes. Finally, we examined the in vivo effects of CECM on inflammation control and cartilage degradation in an experimental OA-induced rat model. The rat model of OA was established by injecting monosodium iodoacetate into the intra-articular knee joint. The rats were then injected with CECM solution. Inflammation control and cartilage degradation were assessed by measuring the serum levels of proinflammatory cytokines and C-telopeptide of type II collagen and performing a histomorphological analysis. CECM was found to be biocompatible and non-immunogenic, and could improve cell proliferation without inducing a toxic reaction. CECM significantly reduced cellular apoptosis due to TNF-α, significantly improved the survival of cells in inflammatory environments, and exerted anti-inflammatory effects. Our findings suggest that CECM is an appropriate injectable material that mediates OA-induced inflammation.

Correction to: Nitric oxide-caused rabbit chondrocyte apoptosis is linked to cytoskeletal protein proteolysis anomaly through intracellular JNK and ERK signal pathways

Correction to: Nitric oxide-caused rabbit chondrocyte apoptosis is linked to cytoskeletal protein proteolysis anomaly through intracellular JNK and ERK signal pathways

Chondrogenic and ameliorated inflammatory effects of chitosan-based biomimetic scaffold loaded with icariin

Icariin (ICA) is a small molecule drug capable of promoting cartilage repair and ameliorating inflammation. Loading ICA into a biomaterial scaffold for cartilage tissue engineering will thus potentially enhance the biological functionality of the engineered scaffold. In this study, short fibers processed from electrospun poly(l-lactide-co-caprolactone) (PLCL) fibers which were prior coated with polydopamine (PDA), were mixed with citric acid doped chitosan solution (CC) for preparing short fibers reinforced chitosan hydrogel (PDA@PLCL/CC) by a freeze-thawing combined freeze-drying method. Thereafter, ICA was loaded into the PDA@PLCL/CC scaffold through physical adsorption to generate a newly engineered biomimetic cartilage scaffold (ICA-PDA@PLCL/CC). Finally, ICA-mediated chondrogenic and ameliorated inflammatory effects of the ICA-PDA@PLCL/CC scaffold were examined in vitro using rabbit chondrocytes. The results showed that the ICA-free PDA@PLCL/CC scaffold possessed appropriate pore size and porosity (> 80%), high water absorbance capacity and improved mechanical performance, and also promoted chondrocyte proliferation and adhesion. The ICA-laden ICA-PDA@PLCL/CC scaffold was evidenced to maintain cytomorphology, upregulate the expression of chondrogenic gene (sox-9), glycosaminoglycan gene (gag), and type Ⅱ collagen gene (col Ⅱ) as well as the synthesis of the cartilage matrix. In the presence of a simulated inflammation, the ICA-PDA@PLCL/CC scaffold was found to reduce chondrocyte fibrosis, effectively downregulate the expression of proinflammatory factors interleukin-6 (il-6), interleukin-1 (il-1), and inducible nitric oxide synthase (inos) in chondrocytes. It can also reduce matrix metalloproteinase-3 (mmp-3) expression and promote the synthesis of the extracellular matrix glycosaminoglycan (GAG) and type II collagen (Col II). The newly developed ICA-PDA@PLCL/CC scaffold may find applications in the regeneration and repair of cartilage defects.

Nitric oxide-caused rabbit chondrocyte apoptosis is linked to cytoskeletal protein proteolysis anomaly through intracellular JNK and ERK signal pathways

Nitric oxide-caused rabbit chondrocyte apoptosis is linked to cytoskeletal protein proteolysis anomaly through intracellular JNK and ERK signal pathways