Cartilage Defects In Rabbits Research Articles

Bioenergetic-active exosomes for cartilage regeneration and homeostasis maintenance.

Cartilage regeneration relies on adequate and continuous bioenergy supply to facilitate cellular differentiation and extracellular matrix synthesis. Chondrocytes frequently undergo energy stress under pathological conditions, characterized by disrupted cellular metabolism and reduced adenosine triphosphate (ATP) levels. However, there has limited progress in modulating energy metabolism for cartilage regeneration thus far. Here, we developed bioenergetic-active exosomes (Suc-EXO) to promote cartilage regeneration and homeostasis maintenance. Suc-EXO exhibited a 5.42-fold increase in ATP content, enabling the manipulation of cellular energy metabolism by fueling the TCA cycle. With continuous energy supply, Suc-EXO promoted BMSC chondrogenic differentiation via the P2X7-mediated PI3K-AKT pathway. Moreover, Suc-EXO improved chondrocyte anabolism and mitochondrial homeostasis via the P2X7-mediated SIRT3 pathway. In a rabbit cartilage defect model, the Suc-EXO-encapsulated hydrogel notably promoted cartilage regeneration and maintained neocartilage homeostasis, leading to 2.26 and 1.53 times increase in Col2 and ACAN abundance, respectively. These findings make a remarkable breakthrough in modulating energy metabolism for cartilage regeneration, offering immense potential for clinical translation.

In situ bioprinting for cartilage repair using a parallel manipulator

Regeneration of large-sized cartilage injury is a challenging endeavor. In vitro bioprinting for cartilage repair has several drawbacks, such as the tedious process of material preparation, potential contamination, and the mismatch between implant and defect. This study aimed to investigate the application of in situ bioprinting in cartilage repair using a parallel manipulator. In particular, the material extrusion rate and printing speed were adjusted to obtain the suitable forming parameters in a custom-made parallel manipulator. Cell experiments were conducted to determine the biocompatibility. Finally, a rabbit cartilage defect model was used to evaluate the feasibility of in situ bioprinting combined with machine vision. The results showed that to achieve optimum printing using the custom-made three-dimensional printer, 400–560 mm/min should be set as the standard printing speed, with an extrusion multiplier of 0.09–0.10. Cartilage defects can be precisely and easily segmented using a bimodal method with a 2% deviation error. In vitro experiments revealed that the utilized materials are highly biocompatible. Furthermore, according to the results from in vivo experiments, in situ bioprinting lends itself useful in the repair of cartilage defects. The overall results confirmed the feasibility of applying a parallel manipulator in in situ bioprinting for cartilage repair. Additional optimizations of the proposed approach are warranted prior to translation into clinical applications in the future.

Nanofiber Composite Microchannel-Containing Injectable Hydrogels for Cartilage Tissue Regeneration.

Articular cartilage tissue is incapable of self-repair and therapies for cartilage defects are still lacking. Injectable hydrogels have drawn much attention in the field of cartilage regeneration. Herein, the novel design of nanofiber composite microchannel-containing hydrogels inspired by the tunnel-piled structure of subway tunnels is proposed. Based on the aldehydized polyethylene glycol/carboxymethyl chitosan (APA/CMCS) hydrogels, thermosensitive gelatin microrods (GMs) are used as a pore-forming agent, and coaxial electrospinning polylactic acid/gelatin fibers (PGFs) loaded with kartogenin (KGN) are used as a reinforcing agent and a drug delivery system to construct the nanofiber composite microchannel-containing injectable hydrogels (APA/CMCS/KGN@PGF/GM hydrogels). The in situ formation, micromorphology and porosity, swelling and degradation, mechanical properties, self-healing behavior, as well as drug release of the nanofiber composite microchannel-containing hydrogels are investigated. The hydrogel exhibits good self-healing ability, and the introduction of PGF nanofibers can significantly improve the mechanical properties. The drug delivery system can realize sustained release of KGN to match the process of cartilage repair. The microchannel structure effectively promotes bone marrow mesenchymal stem cell (BMSC) proliferation and ingrowth within the hydrogels. In vitro and animal experiments indicate that the APA/CMCS/KGN@PGF/GM hydrogels can enhance the chondrogenesis of BMSCs and promote neocartilage formation in the rabbit cartilage defect model.

Post-Implantation Stiffening by a Bioinspired, Double-Network, Self-Healing Hydrogel Facilitates Minimally Invasive Cell Delivery for Cartilage Regeneration.

Injectable hydrogels have demonstrated advantages in cartilage repair by enabling the delivery of cells through a minimally invasive approach. However, several injectable hydrogels suffer from rapid degradation and low mechanical strength. Moreover, higher mechanical stiffness in hydrogels can have a detrimental effect on post-implantation cell viability. To address these challenges, we developed an in situ forming bioinspired double network hydrogel (BDNH) that exhibits temperature-dependent stiffening after implantation. The BDNH mimics the microarchitecture of aggrecan, with hyaluronic acid-conjugated poly(N-isopropylacrylamide) providing rigidity and Schiff base crosslinked polymers serving as the ductile counterpart. BDNHs exhibited self-healing property and enhanced stiffness at physiological temperature. Excellent cell viability, long time cell proliferation, and cartilage specific matrix production were observed in the chondrocytes cultured in the BDNH hydrogel. Evidence of cartilage regeneration in a rabbit cartilage defect model using chondrocyte-laden BDNH has suggested it to be a potential candidate for cartilage tissue engineering.

Highly resilient and fatigue-resistant poly(4-methyl-ε-caprolactone) porous scaffold fabricated via thiol-yne photo-crosslinking/salt-templating for soft tissue regeneration

Elastomeric scaffolds, individually customized to mimic the structural and mechanical properties of natural tissues have been used for tissue regeneration. In this regard, polyester elastic scaffolds with tunable mechanical properties and exceptional biological properties have been reported to provide mechanical support and structural integrity for tissue repair. Herein, poly(4-methyl-ε-caprolactone) (PMCL) was first double-terminated by alkynylation (PMCL-DY) as a liquid precursor at room temperature. Subsequently, three-dimensional porous scaffolds with custom shapes were fabricated from PMCL-DY via thiol-yne photocrosslinking using a practical salt template method. By manipulating the Mn of the precursor, the modulus of compression of the scaffold was easily adjusted. As evidenced by the complete recovery from 90% compression, the rapid recovery rate of >500 mm min−1, the extremely low energy loss coefficient of <0.1, and the superior fatigue resistance, the PMCL20-DY porous scaffold was confirmed to harbor excellent elastic properties. In addition, the high resilience of the scaffold was confirmed to endow it with a minimally invasive application potential. In vitro testing revealed that the 3D porous scaffold was biocompatible with rat bone marrow stromal cells (BMSCs), inducing BMSCs to differentiate into chondrogenic cells. In addition, the elastic porous scaffold demonstrated good regenerative efficiency in a 12-week rabbit cartilage defect model. Thus, the novel polyester scaffold with adaptable mechanical properties may have extensive applications in soft tissue regeneration.

Application of Nano-Calcium Phosphate Coated Porous Tantalum Scaffold in Repair of Rabbit Cartilage Defect

Calcium coated scaffolds and their role in repair of bone defects have been widely studied in the last decades. This study aimed to evaluate the effect of bone morphogenetic protein-7 (BMP-7) loaded nano-calcium phosphate (CaP) coated porous tantalum scaffolds (PTS) on regenerative and reparative potency of cartilage defects in rabbits. We used New Zealand white rabbit cartilage defect models. The subjects were randomly grouped into 4: (1) a control group (no treatment), (2) a PTS group, (3) a CaP/PTS group, and (4) a CaP/PTS/BMP-7 groups. The characterization and in vitro biocompatibility of each scaffold were evaluated. Following scaffold implantation, we evaluated the gross observation score, Micro-CT observation parameters, and the mRNA of target genes. No visible difference was detected in water contact angle (WCA) and cell proliferation activity after co-culture among the PTS, CaP/PTS, and CaP/PTS/BMP-7 scaffold groups (P &gt;0.05). Gross observation scores, trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular mineral density (TMD), bone volume fraction (BV/TV), COL2A1, SOX-9, Aggrecan, and RUNX-2 showed an obvious increase among the PTS, CaP/PTS, and CaP/PTS/BMP-7 groups to those with no treatment (P &lt;0.05). Also, the PPARγ showed an obvious decline (P &lt;0.05). Gross observation scores, Tb.Th, Tb.N, TMD, BV/TV, COL2A1, SOX-9, Aggrecan, and RUNX-2 increased and PPARγ decreased in CaP/PTS/BMP-7 group to PTS and CaP/PTS groups (P &lt;0.05). Our findings indicate that PT scaffolds enhance the reparative potency of cartilage defects in New Zealand rabbits promoted the repair of cartilage defects in rabbits. This effect is boosted among those treated with the BMP-7 loaded nano-CaP coated PTS, and this group showed improved regenerative and reparative potency.

A Cell-Free Silk Fibroin Biomaterial Strategy Promotes In Situ Cartilage Regeneration Via Programmed Releases of Bioactive Molecules.

In situ tissue regeneration using cell-free biofunctional scaffolds has been extensively studied as a promising alternative strategy to promote cartilage repair. In this study, a cartilage-biomimetic silk fibroin (SF)-based scaffold with controlled sequential release of two bioactive molecules is developed. Transforming growth factor-β1 (TGF-β1) is initially loaded onto the SF scaffolds by physical absorption, which are then successively functionalized with bone marrow mesenchymal stem cells (BMSCs)-specific-affinity peptide (E7) via gradient degradation coating of Silk fibroin Methacryloyl (SilMA)/Hyaluronic acid Methacryloyl (HAMA). Such SF-based scaffolds exhibit excellent structural stability and catilage-like mechanical properties, thus providing a desirable 3D microenvironment for cartilage reconstruction. Furthermore, rapid initial release of E7 during the first few days, followed by slow and sustained release of TGF-β1 for as long as few weeks, synergistically induced the recruitment of BMSCs and chondrogenic differentiation of them in vitro. Finally, in vivo studies indicate that the implantation of the biofunctional scaffold markedly promote in situ cartilage regeneration in a rabbit cartilage defect model. It is believed that this cartilage-biomimetic biofunctional SF-based scaffold with sequential controlled release of E7 and TGF-β1 may have a promising potential for improved cartilage tissue engineering.

Culture of Mesenchymal Stem Cells Derived From the Infrapatellar Fat Pad Without Enzyme and Preliminary Study on the Repair of Articular Cartilage Defects in Rabbits.

Objective: The aim of the study was to evaluate the advantages of without enzyme isolating patellar fat pad-derived mesenchymal stem cells (IPFP-SCs) and the feasibility of cartilage repair. Methods: The IPFP-SCs were isolated using the without enzyme method and compared with the IPFP-SCs obtained by the traditional enzyme digestion method in terms of cell proliferation ability, characterization, and differentiation ability, and the differences in chondrogenic induction and differentiation between the two groups were compared. Twenty-four New Zealand rabbits were randomly divided into four groups (n = 6). After the articular cartilage defects were modeled, different preparations were injected into the joint cavity. The rabbits in the group A were injected with the mixture of IPFP-SCs and pure PRP (P-PRP), separated using the without enzyme method, while those in the group B were injected with the mixture of IPFP-SCs and P-PRP separated with the digestion method, while those in the group C were injected with SVF separated using the without enzyme method, and those in the group D were injected with normal saline. At 6 weeks and 12 weeks after operation, the cartilage repair of rabbit joint specimens was observed and evaluated by gross observation and histological staining, and the effects of different IPFP-SCs application forms in repairing cartilage defects were compared. Results: The time required to obtain IPFP-SCs by enzyme-free isolation was significantly less than that by enzyme digestion, while the acquisition rate of primary cells was significantly lower than that by enzyme digestion. After culture and amplification, the two IPFP-SCs from different sources did not show significant differences in cell proliferation, cell phenotype, and differentiation ability. In animal experiments, groups A and B had the best effect on the repair of cartilage defects, and there was no significant difference between the two groups. The repair effect in group C was weaker than that in the former two groups, but it was relatively better than that in group D. Conclusion: It is more time-saving to obtain IPFP-SCs by the without enzyme method than by enzymatic digestion, and there is no significant difference in cell identification and differentiation potential between the two methods. However, the rate of obtaining primary cells was significantly lower than that with the enzyme digestion method. IPFP-SCs showed good repair effect in the rabbit animal cartilage defect model, providing ideas and reference for the clinical application of stem cells in repairing articular cartilage.

Application of tissue-derived bioink for articular cartilage lesion repair

Articular cartilage (AC) lesions are common but remain a great challenge for researchers and clinicians mainly due to their poor self-healing capability. Decellularized cartilage extracellular matrix (dCECM) derived from natural cartilage, and the incorporated growth factors have been used for potential chondrocyte induction and cartilage tissue regeneration. Moreover, infrapatellar fat pad adipose-derived stem cells (IPFP-ADSCs) have been proven to be an optimal source of seeded cells for AC lesion restoration. Therefore, the therapeutic role of dCECM-incorporated bioink with IPFP-ADSCs loaded in 3D (three-dimensional) scaffolds remain to be explored using an osteochondral defect model. In this work, we successfully extracted IPFP-ADSCs and isolated dCECMs, which were then mixed in a temperature-responsive hydrogel to form a 3D bioink. The 3D bioprinting scaffolds printed with dCECM successfully facilitated chondrogenic differentiation-related growth factor expression in IPFP-ADSCs. Most importantly, implantation of the 3D dCECMs with an IPFP-ADSC-loaded scaffold was capable of providing a favorable cell matrix for stem cell proliferation and promoted chondrogenic differentiation, thereby greatly enhancing successful cartilage repair in rabbit cartilage defects.

Effect of silk fibroin microcarrier loaded with clematis total saponins and chondrocytes on promoting rabbit knee articular cartilage defects repair

To prepare the silk fibroin microcarrier loaded with clematis total saponins (CTS) (CTS-silk fibroin microcarrier), and to investigate the effect of microcarrier combined with chondrocytes on promoting rabbit knee articular cartilage defects repair. CTS-silk fibroin microcarrier was prepared by high voltage electrostatic combined with freeze drying method using the mixture of 5% silk fibroin solution, 10 mg/mL CTS solution, and glycerin. The samples were characterized by scanning electron microscope and the cumulative release amount of CTS was detected. Meanwhile, unloaded silk fibroin microcarrier was also prepared. Chondrocytes were isolated from knee cartilage of 4-week-old New Zealand rabbits and cultured. The 3rd generation of chondrocytes were co-cultured with the two microcarriers respectively for 7 days in microgravity environment. During this period, the adhesion of chondrocytes to microcarriers was observed by inverted phase contrast microscope and scanning electron microscope, and the proliferation activity of cells was detected by cell counting kit 8 (CCK-8), and compared with normal cells. Thirty 3-month-old New Zealand rabbits were selected to make bilateral knee cartilage defects models and randomly divided into 3 groups ( n=20). Knee cartilage defects in group A were not treated, and in groups B and C were filled with the unloaded silk fibroin microcarrier-chondrocyte complexes and CTS-silk fibroin microcarrier-chondrocyte complexes, respectively. At 12 weeks after operation, the levels of matrix metalloproteinase 9 (MMP-9), MMP-13, and tissue inhibitor of MMP 1 (TIMP-1) in articular fluid were detected by ELISA. The cartilage defects were collected for gross observation and histological observation (HE staining and toluidine blue staining). Western blot was used to detect the expressions of collagen type Ⅱ and proteoglycan. The inflammatory of joint synovium was observed by histological staining and inducible nitric oxide synthase (iNOS) immunohistochemical staining. The CTS-silk fibroin microcarrier was spherical, with a diameter between 300 and 500 μm, a porous surface, and a porosity of 35.63%±3.51%. CTS could be released slowly in microcarrier for a long time. Under microgravity, the chondrocytes attached to the surface of the two microcarriers increased gradually with the extension of culture time, and the proliferation activity of chondrocytes at 24 hours after co-culture was significantly higher than that of normal chondrocytes ( P<0.05). There was no significant difference in proliferation activity of chondrocytes between the two microcarriers ( P>0.05). In vivo experiment in animals showed that the levels of MMP-9 and MMP-13 in group C were significantly lower than those in groups A and B ( P<0.05), and the level of TIMP-1 in group C was significantly higher ( P<0.05). Compared with group A, the cartilage defects in groups B and C were filled with repaired tissue, and the repaired surface of group C was more complete and better combined with the surrounding cartilage. Histological observation and Western blot analysis showed that the International Cartilage Repair Scoring (ICRS) and the relative expression levels of collagen type Ⅱ and proteoglycan in groups B and C were significantly better than those in group A, and group C was significantly better than group B ( P<0.05). The histological observation showed that the infiltration of synovial inflammatory cells and hyperplasia of small vessels significantly reduced in group C compared with groups A and B. iNOS immunohistochemical staining showed that the expression of iNOS in group C was significantly lower than that in groups A and B ( P<0.05). CTS-silk fibroin microcarrier has good CTS sustained release effect and biocompatibility, and can promote the repair of rabbit cartilage defect by carrying chondrocyte proliferation in microgravity environment.

Induction of chondrogenesis with a RANKL-binding peptide, WP9QY, in vitro and in vivo in a rabbit model

WP9QY (W9) is a receptor activator of nuclear factor-κB ligand (RANKL)-binding peptide that inhibits osteoclastogenesis by blunting the RANKL-RANK interaction, and also increases osteoblastogenesis via RANKL reverse signaling. W9 has dual effects on osteoclasts and osteoblasts; however, it is unknown whether the peptide has an effect on chondrocytes. Here, we report that W9 induces proliferation and differentiation of chondrocytes in vitro and repairs full-thickness articular cartilage defects in vivo. W9 stimulated chondrocyte differentiation in a two-dimensional (2D) culture of human mesenchymal stem cells (hMSCs), and transforming growth factor β3 (TGF-β3) showed synergistic effects with W9 on chondrogenesis. W9 enlarged the size of 3D pellet cultures of hMSCs and produced chondrocyte-specific matrices, especially in combined treatment with TGF-β3. The peptide also stimulated proliferation of hMSCs with induction of expression of chondrogenesis-related genes. Several RANKL inhibitors had no effect on chondrocytic differentiation. RANKL-knockdown experiments showed that W9 did not induce chondrogenesis through RANKL, but did induce osteoblastogenesis through RANKL. Intraarticular injection of W9 resulted in significant repair of full-thickness articular cartilage defects in rabbits. Taken together, these results suggest that W9 ameliorates the articular cartilage defects by increasing the volume of cartilaginous matrices with accompanying induction of proliferation and differentiation of chondrocytes via mechanisms independent of RANKL inhibition and RANKL reverse signaling. Since no pharmaceuticals are clinically available for treatment of cartilage damage such as osteoarthritis, our findings demonstrate the potential of W9 to address the unmet medical needs.

Scrapie-Responsive Gene 1 Promotes Chondrogenic Differentiation of Umbilical Cord Mesenchymal Stem Cells via Wnt5a.

Objective Repair of cartilage defects, a common condition resulting from many factors, is still a great challenge. Based on their chondrogenic differentiation ability, mesenchymal stem cell- (MSC-) based cartilage regeneration is a promising approach for cartilage defect repair. However, MSC differentiation into chondroblasts or related cell lineages is elaborately controlled by stem cell differentiation stage factors and affected by an array of bioactive elements, which may impede the efficient production of target cells. Thus, identifying a single transcription factor to promote chondrogenic differentiation is critical. Herein, we explored the mechanism by which scrapie-responsive gene 1 (SCRG1), a candidate gene for cartilage regeneration promotion, regulates chondrogenic differentiation of MSCs. Methods Expression of SCRG1 was detected in umbilical cord-derived MSCs (UCMSCs) by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and immunohistochemical analysis during chondrogenic differentiation. The function of SCRG1 in chondrogenic potential was evaluated after gene knockdown or overexpression by lentiviral vectors. Finally, a rabbit cartilage defect model was established to evaluate the effect of SCRG1 on cartilage repair in vivo. Results Expression of SCRG1 was upregulated during in vitro chondrogenic differentiation of UCMSCs. SCRG1 knockdown inhibited chondrogenic differentiation of UCMSCs, while SCRG1 overexpression promoted chondrogenic differentiation of UCMSCs in vitro. In addition, UCMSC overexpressing SCRG1 promoted cartilage repair in vivo. Mechanistically, SCRG1 promoted chondrogenic differentiation via upregulation of Wnt5a expression and subsequent inhibition of β-catenin. Conclusion Our results showed that SCRG1 promotes chondrogenic differentiation of UCMSCs by inhibiting canonical Wnt/β-catenin signaling through Wnt5a. Our findings provide a future target for chondrogenic differentiation and cartilage regeneration.

Human adipose-derived stromal/stem cells expressing doublecortin improve cartilage repair in rabbits and monkeys

Localized cartilage lesions in early osteoarthritis and acute joint injuries are usually treated surgically to restore function and relieve pain. However, a persistent clinical challenge remains in how to repair the cartilage lesions. We expressed doublecortin (DCX) in human adipose-derived stromal/stem cells (hASCs) and engineered hASCs into cartilage tissues using an in vitro 96-well pellet culture system. The cartilage tissue constructs with and without DCX expression were implanted in the knee cartilage defects of rabbits (n = 42) and monkeys (n = 12). Cohorts of animals were euthanized at 6, 12, and 24 months after surgery to evaluate the cartilage repair outcomes. We found that DCX expression in hASCs increased expression of growth differentiation factor 5 (GDF5) and matrilin 2 in the engineered cartilage tissues. The cartilage tissues with DCX expression significantly enhanced cartilage repair as assessed macroscopically and histologically at 6, 12, and 24 months after implantation in the rabbits and 24 months after implantation in the monkeys, compared to the cartilage tissues without DCX expression. These findings suggest that hASCs expressing DCX may be engineered into cartilage tissues that can be used to treat localized cartilage lesions.

Spatiotemporal regulation of endogenous MSCs using a functional injectable hydrogel system for cartilage regeneration

Hydrogels have been extensively favored as drug and cell carriers for the repair of knee cartilage defects. Recruiting mesenchymal stem cells (MSCs) in situ to the defect region could reduce the risk of contamination during cell delivery, which is a highly promising strategy to enhance cartilage repair. Here, a cell-free cartilage tissue engineering (TE) system was developed by applying an injectable chitosan/silk fibroin hydrogel. The hydrogel system could release first stromal cell-derived factor-1 (SDF-1) and then kartogenin (KGN) in a unique sequential drug release mode, which could spatiotemporally promote the recruitment and chondrogenic differentiation of MSCs. This system showed good performance when formulated with SDF-1 (200 ng/mL) and PLGA microspheres loaded with KGN (10 μΜ). The results showed that the hydrogel had good injectability and a reticular porous structure. The microspheres were distributed uniformly in the hydrogel and permitted the sequential release of SDF-1 and KGN. The results of in vitro experiments showed that the hydrogel system had good cytocompatibility and promoted the migration and differentiation of MSCs into chondrocytes. In vivo experiments on articular cartilage defects in rabbits showed that the cell-free hydrogel system was beneficial for cartilage regeneration. Therefore, the composite hydrogel system shows potential for application in cell-free cartilage TE.

Hyaluronic acid hydrogel encapsulated BMP-14-modified ADSCs accelerate cartilage defect repair in rabbits

BackgroundCartilage defect has a limited capacity to heal. In this context, we hypothesized that hyaluronic acid (HA) hydrogel encapsulated BMP-14-modified adipose-derived mesenchymal stem cells (ADSCs) could accelerate cartilage defect repair in rabbits.MethodsADSCs were isolated and identified by flow cytometry. ADSCs were treated with adenovirus vector encoding BMP-14 (Ad-BMP-14) or adenovirus vector encoding control (Ad-ctrl). Real-time PCR (RT-PCR) and western blot assay was performed to verify the transfection efficacy and chondrogenic differentiation markers (ACAN, Collagen II and SOX9). Rabbit cartilage defect model was performed and randomly divided into following groups: control group, HA hydrogel + ADSCs, ADSCs, HA hydrogel + Lv-ctrl-ADSCs, HA hydrogel + BMP-14 transfected ADSCs. At 6, 9 and 12 weeks after surgery, scanning electron microscopy, hematoxylin–eosin, Safranin-O/Fast Green and immunohistochemical staining for Collagen II were performed to determine the role of HA hydrogel encapsulated BMP-14-modified ADSCs in cartilage repair in vivo.ResultsADSCs were successfully isolated and positively expressed CD29, CD44 and CD90. Transfection efficacy of Ad-BMP-14 was verified by RT-PCR and western blot assay. Moreover, Ad-BMP-14 could significantly increased chondrogenic differentiation markers (ACAN, Collagen II and SOX9). The LV-BMP-14-ADSCs and HA hydrogel + LV-BMP-14-ADSCs groups revealed smoother surface cartilage repair that was level with the surrounding cartilage and almost complete border integration.ConclusionsHA hydrogel encapsulated BMP-14-modified ADSCs accelerate cartilage defect repair in rabbits. We need to further validate the specific mechanism of action of HA hydrogel encapsulated LV-BMP-14-ADSCs involved in the repairing cartilage damage in vivo.

In vivo efficacy of 3D-printed elastin-gelatin-hyaluronic acid scaffolds for regeneration of nasal septal cartilage defects.

Nasal septal cartilage perforations occur due to the different pathologies. Limited healing ability of cartilage results in remaining defects and further complications. This study sought to assess the efficacy of elastin-gelatin-hyaluronic acid (EGH) scaffolds for regeneration of nasal septal cartilage defects in rabbits. Defects (4 × 7 mm) were created in the nasal septal cartilage of 24 New Zealand rabbits. They were randomly divided into four groups: Group 1 was the control group with no further intervention, Group 2 received EGH scaffolds implanted in the defects, Group 3 received EGH scaffolds seeded with autologous auricular chondrocytes implanted in the defects, and Group 4 received EGH scaffolds seeded with homologous auricular chondrocytes implanted in the defects. After a 4-month healing period, computed tomography (CT) and magnetic resonance imaging (MRI) scans were obtained from the nasal septal cartilage, followed by histological evaluations of new tissue formation. Maximum regeneration occurred in Group 2, according to CT, and Group 3, according to both T1 and T2 images with 7.68 ± 1.36, 5.44 ± 2.41, and 8.72 ± 3.02 mm2 defect area respectively after healing. The difference in the defect size was statistically significant after healing between the experimental groups. Group 3 showed significantly greater regeneration according to CT scans and T1 and T2 images. The neocartilage formed over the underlying old cartilage with no distinct margin in histological evaluation. The EGH scaffolds have the capability of regeneration of nasal cartilage defects and are able to integrate with the existing cartilage; yet, they present the best results when pre-seeded with autologous chondrocytes.

A cell-free ROS-responsive hydrogel/oriented poly(lactide-co-glycolide) hybrid scaffold for reducing inflammation and restoring full-thickness cartilage defects in vivo

The modulation of inflammation in tissue microenvironment takes an important role in cartilage repair and regeneration. In this study, a novel hybrid scaffold was designed and fabricated by filling a reactive oxygen species (ROS)-scavenging hydrogel (RS Gel) into a radially oriented poly(lactide-co-glycolide) (PLGA) scaffold. The radially oriented PLGA scaffolds were fabricated through a temperature gradient-guided phase separation and freeze-drying method. The RS Gel was formed by crosslinking the mixture of ROS-responsive hyperbranched polymers and biocompatible methacrylated hyaluronic acid (HA-MA). The hybrid scaffolds exhibited a proper compressive modulus, good ROS-scavenging capability, and cell compatibility. In vivo tests showed that the hybrid scaffolds significantly regulated inflammation and promoted regeneration of hyaline cartilage after they were implanted into full-thickness cartilage defects in rabbits for 12 w. In comparison with the PLGA scaffolds, the neo-cartilage in the hybrid scaffolds group possessed more deposition of glycosaminoglycans and collagen type II, and were well integrated with the surrounding tissue.

Porcine fibrin sealant combined with autologous chondrocytes successfully promotes full-thickness cartilage regeneration in a rabbit model.

Xenogeneic porcine fibrin sealant (PFS), derived from porcine blood, was used as a scaffold for cartilage tissue engineering. PFS has a porous microstructure, biocompatibility and degradation, and it provides a perfect extracellular matrix environment for the adhesion and proliferation of chondrocytes. Recently, PFS in combination with autologous chondrocytes (ACs) were used to study the microstructure of PFS scaffolds and promotion effect on the proliferation and migration of ACs. In this study, we investigated the effects of PFS in combination with ACs on the healing of cartilage defects in rabbits. A full‐thickness cartilage defect was made in the femoral trochlear in rabbits, subsequently, three surgical procedures were used to repair the defect, namely: the defect was treated with microfracture (MF group); the defect was filled with PFS alone (PFS group) or in combination with ACs (PFS + ACs group); the unrepaired cartilage defects served as the control group (CD group). Three and 6 months after the operation, the reparative effect was evaluated using medical imaging, gross scoring, pathological staining, biomechanical testing and biochemical examination. The PFS group showed a limited effect on defect repair, this result was significantly worse than the MF group. The best reparative effect was observed in the PFS + ACs group. These results hinted that PFS in combination with autologous chondrocytes has broad prospects for clinical applications in cartilage tissue engineering.

Recapitulating Developmental Condensation and Constructing Self-organised Cartilaginous Tissue for Cartilage Regeneration.

To develop a novel chondrocyte condensation culture strategy recapitulating developmental condensation and construct self-organised cartilaginous tissue for cartilage regeneration. Cell-condensation aggregate (CCA) was generated using the condensation culture method by sequential cell seeding. The chondrification capacities and biocompatibilities of CCA were assessed by comparison with the cell-scaffold complex (CSC), which was constructed by cell-scaffold coculture. Preclinical studies including implantation into nude mice subcutaneously and cartilage defect repair in rabbits were performed. CCA constructed by condensation culture exhibited a morphology of self-organised cartilaginous tissue. Meanwhile, the condensation culture inhibited or abolished expression of HOX genes including HOXC4 and HOXD8, which was partially consistent with developmental HOX gene expression patterns and associated with enhanced regeneration capacities. Compared with CSC, CCA showed a higher capacity for chondrification and regeneration of rabbit cartilage defects. The therapeutic assessments indicate that CCA is an efficient therapeutic tool for cartilage regeneration, providing a new strategy for tissue engineering by mimicking developmental events.

Intra-osseous application of plasma rich in growth factors to treat acute cartilage defects in rabbits: evaluation of blood biomarkers (hyaluronic acid and collagen type II cleavage epitope)

Purpose: Osteoarthritis (OA) is the most frequent musculoskeletal disorder, and it is estimated to affect over 303 million people worldwide. Pain is the most predominant symptom followed by mobility limitations, having a great impact in both physical and mental wellbeing of patients. OA places a significant socio-economic burden on societies, and due to the overall ageing of the population and the increasing prevalence of obesity it is expected an increase of 50% in the number of people with OA over the next 20 years.