Rabbit Osteochondral Defect Research Articles

An Injectable Bioorthogonal Dextran Hydrogel for Enhanced Chondrogenesis of Primary Stem Cells.

The purpose of this study is to corroborate the feasibility of an injectable dextran hydrogel, in situ formed through a catalyst-free bioorthogonal reaction, for cartilage regeneration with adult chondrocytes or adipose-derived stem cells (ADSCs). To this end, an injectable dextran (dextran-AN) hydrogel encapsulating the rabbit adult chondrocytes or rabbit ADSCs (rADSCs) or human ADSCs (hADSCs) was successfully prepared by simply incubating the cells with dibenzocyclooctyne-dextran conjugate and azide-dextran conjugate under physiological conditions through a copper-free bioorthogonal reaction without using additional reagents. The possibility of dextran-AN hydrogel/adult rabbit chondrocyte constructs for in vivo chondrogenesis was first assessed in a rabbit osteochondral defect model. Data indicated that the hydrogel was biocompatible against surrounding tissue and could promote adult chondrocyte survival and in vivo chondrogenesis within 8 weeks. Next, in vitro and in vivo chondrogenetic differentiation of rADSCs encapsulating in dextran-AN hydrogel was studied systemically. Compared to the agarose hydrogel as a positive control, the dextran-AN hydrogel elicited comparable ability to support in vitro chondrogenesis of rADSCs within 3 weeks but caused better cartilage regeneration within 6 weeks in a rabbit osteochondral defect model. Furthermore, miR29A downregulating of hADSCs was applied for in vivo chondrogenesis by subcutaneous in situ formation of dextran-AN hydrogel containing the hADSCs in a balb/c nude mouse model. Within 4-week regeneration, the hydrogel group illustrated upregulated mRNA expression level of chondrogenesis-related biomarkers. In addition, improved production of neocartilage extracellular matrices (type-II collagen and glycosaminoglycan) was found for miR29A-downregulatd hADSC group in comparison with miR29A-upregulated hADSC and untreated hADSC control groups. The results of this study show that bioorthogonal dextran-based hydrogel is capable of supporting in vitro and in vivo chondrogenesis of chondrocytes and human stem cells, thus highlighting high feasibility of bioorthogonal hydrogels for clinical translation in stem cell-based cartilage regeneration.

Demineralized cancellous bone seeded with allogeneic chondrocytes for repairing articular osteochondral defects in rabbits

To evaluate the effect of demineralized cancellous bone (DCB) seeded with allogeneic chondrocytes for repairing articular osteochondral defects in rabbits. Articular chondrocytes were isolated from a 1-month-old male New Zealand rabbit for primary culture. The passage 1 chondrocytes were seeded onto prepared rabbit DCB scaffold to construct tissue-engineered cartilage and cultured in vitro for 2 weeks. Full-thickness articular osteochondral defects (3 mm both in diameter and depth) were created on both sides of the femoral medial condyles in 30 New Zealand white rabbits (age 4- 5 months). In 20 of the rabbits, the defects were filled with the tissue-engineered cartilage on the right side (group A) and with DCB only on the left side (group B); the remaining 10 rabbits did not receive any implantation in the defects to serve as the control (group C). At 1, 3, and 6 months after the implantation, tissue samples were collected from the defects for macroscopic observation and histological examination with Toluidine blue (TB) and collagen type Ⅱ staining. The effect of defect repair using the tissue-engineered cartilage was assessed at 6 months based on the histological scores. The prepared DCB had a spongy 3D structure with open and interconnected micropores of various sizes and showed good plasticity and mechanical strength. DCB began to degrade within 1 month after implantation and was totally absorbed at 3 months. At 6 months after implantation, the defects filled with the chondrocyte-seeded DCB were repaired mainly by hyaline-like cartilage tissues, which were well integrated to the adjacent cartilage without clear boundaries and difficult to recognize. The chondrocytes were located in the lacunate and arranged in vertical columns in the deep repaired tissue, where matrix proteoglycans and collagen type Ⅱ were distributed homogeneously close to the normal cartilage. The subchondral bone plate was reconstructed completely. The defects implanted with DCB only were filled with fibrocartilage tissue, as compared with fibrous tissue in the control defects. The histological scores in group A were significantly superior to those in group B and C (P < 0.05), but the scores for subchondral bone plate reconstruction were comparable between groups A and B at 6 months. DCB is a good scaffold material for preparing tissue-engineered cartilage, and chondrocyte- seeded DCB can repair articular osteochondral defects by inducing the generation of hayline-like cartilage.

Enhanced articular cartilage regeneration with SIRT1-activated MSCs using gelatin-based hydrogel

To investigate the functional effects of resveratrol (RSV) on mesenchymal stem cells (MSCs), we treated MSCs with RSV continuously during ex vivo expansion. MSCs were continuously treated with RSV from passage (P) 0 to P5. A proliferative capacity of RSV-treated MSCs was higher than that of non-treated MSCs and similar with P1-MSCs. Continuous treatment of RSV on MSCs increased the stemness and inhibited the senescence. During chondrogenic differentiation in vitro, RSV-treated MSCs had higher differentiation potential and reduced hypertrophic maturation, which are limitations for hyaline cartilage formation. The histological analysis of micromass demonstrated increased chondrogenic differentiation potential. We further explored the therapeutic effectiveness of this method in a rabbit osteochondral defect model. A rabbit osteochondral defect model was established to investigate the hyaline cartilage regeneration potential of RSV-treated MSCs. Moreover, the cartilage regeneration potential of RSV-treated MSCs was greater than that of untreated MSCs. The expression levels of chondrogenic markers increased and those of hypertrophic markers decreased in RSV-treated MSCs compared with untreated MSCs. Sustained treatment of RSV on MSCs during ex vivo expansion resulted in the maintenance of stemness and enhanced chondrogenic differentiation potential. Consequentially, highly efficient MSCs promoted superior hyaline cartilage regeneration in vivo. This novel treatment method provides a basis for cell-based tissue engineering.

3D printing of a lithium-calcium-silicate crystal bioscaffold with dual bioactivities for osteochondral interface reconstruction

It is difficult to achieve self-healing outcoming for the osteochondral defects caused by degenerative diseases. The simultaneous regeneration of both cartilage and subchondral bone tissues is an effective therapeutic strategy for osteochondral defects. However, it is challenging to design a single type of bioscaffold with suitable ionic components and beneficial osteo/chondral-stimulation ability for regeneration of osteochondral defects. In this study, we successfully synthesized a pure-phase lithium calcium silicate (Li2Ca4Si4O13, L2C4S4) bioceramic by a sol-gel method, and further prepared L2C4S4 scaffolds by using a 3D-printing method. The compressive strength of L2C4S4 scaffolds could be well controlled in the range of 15–40 MPa when pore size varied from 170 to 400 μm. L2C4S4 scaffolds have been demonstrated to possess controlled biodegradability and good apatite-mineralization ability. At a certain concentration range, the ionic products from L2C4S4 significantly stimulated the proliferation and maturation of chondrocytes, as well as promoted the osteogenic differentiation of rBMSCs. L2C4S4 scaffolds simultaneously promoted the regeneration of both cartilage and subchondral bone as compared to pure β-TCP scaffolds in rabbit osteochondral defects. These findings suggest that 3D-printed L2C4S4 scaffolds with such specific ionic combination, high mechanical strength and good degradability as well as dual bioactivities, represent a promising biomaterial for osteochondral interface reconstruction.

Application of combined porous tantalum scaffolds loaded with bonemorphogenetic protein 7 to repair of osteochondral defect in rabbits.

Porous tantalum (PT) has been widely used in orthopaedic applications for low modulus of elasticity, excellent biocompatibility, and the microstructures similar to cancellous bone. In order to improve the biological activity of PT, biologically active factors can be combined with the material. The purpose of this study was to investigate if bone morphogenetic protein 7 (BMP-7) modifications could enhance the repairing of cartilage of PT in osteochondral defect in medial femoral condyle of rabbits. A cylindrical osteochondral defect model was created on the animal medial femoral condyle of and filled as follows: PT modified with BMP-7 for MPT group, non-modified PT for the PT group, while no implants were used for the blank group. The regenerated osteochondral tissue was assessed and analyzed by histological observations at four, eight and 16weeks post-operation and evaluated in an independent and blinded manner by five different observers using a histological score. Osteochondral and subchondral bone defect repair was assessed by micro-CT scan at 16 weeks post-operation, while the biomechanical test was performed at 16 weeks post-operation. Briefly, higher overall histological score was observed in the MPT group compared to PT group. Furthermore, more new osteochondral tissue and bone formed at the interface and inside the inner pores of scaffolds of the MPT group compared to PT group. Additionally, the micro-CT data suggested that the new bone volume fractions and the quantity and quality of trabecular bone, as well as the maximum release force of the bone, were higher in the MPT group compared to PT group. We demonstrated that the applied modified PT with BMP-7 promotes excellent subchondral bone regeneration and may serve as a novel approach for osteochondral defects repair.

Gradient nano-engineered in situ forming composite hydrogel for osteochondral regeneration

Fabrication of anisotropic osteochondral-mimetic scaffold with mineralized subchondral zone and gradient interface remains challenging. We have developed an injectable semi-interpenetrating network hydrogel construct with chondroitin sulfate nanoparticles (ChS-NPs) and nanohydroxyapatite (nHA) (∼30–90 nm) in chondral and subchondral hydrogel zones respectively. Mineralized subchondral hydrogel exhibited significantly higher osteoblast proliferation and alkaline phosphatase activity (p < 0.05). Osteochondral hydrogel exhibited interconnected porous structure and spatial variation with gradient interface of nHA and ChS–NPs. Microcomputed tomography (μCT) demonstrated nHA gradation while rheology showed predominant elastic modulus (∼930 Pa) at the interface. Co–culture of osteoblasts and chondrocytes in gradient hydrogels showed layer–specific retention of cells and cell-cell interaction at the interface. In vivo osteochondral regeneration by biphasic (nHA or ChS) and gradient (nHA + ChS) hydrogels was compared with control using rabbit osteochondral defect after 3 and 8 weeks. Complete closure of defect was observed in gradient (8 weeks) while defect remained in other groups. Histology demonstrated collagen and glycosaminoglycan deposition in neo–matrix and presence of hyaline cartilage–characteristic matrix, chondrocytes and osteoblasts. μCT showed mineralized neo–tissue formation, which was confined within the defect with higher bone mineral density in gradient (chondral: 0.42 ± 0.07 g/cc, osteal: 0.64 ± 0.08 g/cc) group. Further, biomechanical push-out studies showed significantly higher load for gradient group (378 ± 56 N) compared to others. Thus, the developed nano-engineered gradient hydrogel enhanced hyaline cartilage regeneration with subchondral bone formation and lateral host-tissue integration.

Osteochondral repair using an acellular dermal matrix-pilot in vivo study in a rabbit osteochondral defect model.

RabADM alone resulted in neocartilage formation similar to native cartilage. IPFP-MSCs limited osteochondral repair and contributed to fibrosis, even in combination with the rabADM. Further studies using ADM for osteochondral repair are warranted in a more appropriate pre-clinical model of osteochondral repair. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1919-1928, 2018.

Repair of osteochondral defects in a rabbit model with artificial cartilage particulates derived from cultured collagen-chondrocyte microspheres

Tissue engineered cartilage has become a promising candidate for restoration of defective cartilage, but is normally associated with problems including limited tissue size, inferior mechanical properties, poor tissue homogeneity and integrative properties compared to the native cartilage. In this study, we utilised our recently developed microsphere culture technique to fabricate artificial cartilage particulates (ACPs) using collagen hydrogel microspheres with allogenic chondrocytes. These ACPs were used to repair rabbit osteochondral defects in vivo. The results demonstrated that the optimised ACPs showed better cartilage repair and integration into the host tissue. Moreover, the mechanical integrity of ACPs protected the tissue underneath and enhanced the subchondral bone formation. After 3 months of surgery, the subchondral bone volume had recovered to a similar level to the natural tissue. Together, these results suggested that the ACPs prepared using our microsphere culture technique show great potential for osteochondral repair in future clinical applications.

3D printing of Mo-containing scaffolds with activated anabolic responses and bi-lineage bioactivities.

When osteochondral tissues suffer from focal or degenerative lesions caused by trauma or disorders, it is a tough challenge to regenerate them because of the limited self-healing capacity of articular cartilage. In this study, a series of Mo-doped bioactive glass ceramic (Mo-BGC) scaffolds were prepared and then systematically characterized. The released MoO42- ions from 7.5Mo-BGC scaffolds played a vital role in regenerating articular cartilage and subchondral bone synchronously.Methods: The Mo-BGC scaffolds were fabricated through employing both a sol-gel method and 3D printing technology. SEM, EDS, HRTEM, XRD, ICPAES and mechanical strength tests were respectively applied to analyze the physicochemical properties of Mo-BGC scaffolds. The proliferation and differentiation of rabbit chondrocytes (RCs) and human bone mesenchymal stem cells (HBMSCs) cultured with dilute solutions of 7.5Mo-BGC powder extract were investigated in vitro. The co-culture model was established to explore the possible mechanism of stimulatory effects of MoO42- ions on the RCs and HBMSCs. The efficacy of regenerating articular cartilage and subchondral bone using 7.5Mo-BGC scaffolds was evaluated in vivo.Results: The incorporation of Mo into BGC scaffolds effectively enhanced the compressive strength of scaffolds owing to the improved surface densification. The MoO42- ions released from the 7.5Mo-BGC powders remarkably promoted the proliferation and differentiation of both RCs and HBMSCs. The MoO42- ions in the co-culture system significantly stimulated the chondrogenic differentiation of RCs and meanwhile induced the chondrogenesis of HBMSCs. The chondrogenesis stimulated by MoO42- ions happened through two pathways: 1) MoO42- ions elicited anabolic responses through activating the HIF-1α signaling pathway; 2) MoO42- ions inhibited catabolic responses and protected cartilage matrix from degradation. The in vivo study showed that 7.5Mo-BGC scaffolds were able to significantly promote cartilage/bone regeneration when implanted into rabbit osteochondral defects for 8 and 12 weeks, displaying bi-lineage bioactivities.Conclusion: The 3D-printed Mo-BGC scaffolds with bi-lineage bioactivities and activated anabolic responses could offer an effective strategy for cartilage/bone interface regeneration.

Silk fibroin-chondroitin sulfate scaffold with immuno-inhibition property for articular cartilage repair.

Severe cartilage defect such as osteoarthritis (OA) is difficult to self-repair because of its avascular, aneural and alymphatic nature. Current scaffolds often focus on providing sufficient mechanical support or bio-mimetic structure to promote cartilage repair. Thus, silk has been adopted and investigated broadly. However, inflammation is one of the most important factors in OA. But few scaffolds for cartilage repair reported anti-inflammation property. Meanwhile, chondroitin sulfate (CS) is a glycosaminoglycan present in the natural cartilage ECM, and has exhibited a number of useful biological properties including anti-inflammatory activity. Thus, we designed this silk-CS scaffold and proved that this scaffold exhibited good anti-inflammatory effects both in vitro and in vivo, promoted the repair of articular cartilage defect in animal model.

BMP-2 gene activated muscle tissue fragments for osteochondral defect regeneration in the rabbit knee.

Previously published data indicate that BMP-2 gene activated muscle tissue grafts can repair large bone defects in rats. This innovative abbreviated ex vivo gene therapy is appealing because it does not require elaborative and time-consuming extraction and expansion of cells. Hence, in the present study, we evaluated the potential of this expedited tissue engineering approach for regenerating osteochondral defects in rabbits. Autologous muscle tissue grafts from female White New Zealand rabbits were directly transduced with an adenoviral BMP-2 vector or remained unmodified. Osteochondral defects in the medial condyle of rabbit knees were treated with either BMP-2 activated muscle tissue implants or unmodified muscle tissue or remained empty. After 13weeks, repair of osteochondral defects was examined by biomechanical indentation testing and by histology/imunohistochemistry applying an extended O'Driscoll scoring system and histomorphometry. Biomechanical investigations revealed a trend towards slightly improved mechanical properties of the group receiving BMP-2 activated muscle tissue compared to unmodified muscle treatment and empty defect controls. However, a statistically significant difference was noted only between BMP-2 muscle and unmodified muscle treatment. Also, histological evaluation resulted in slightly higher histological scores and improved collagen I/II ratio without statistical significance in the BMP-2 treatment group. Histomorphometry indicated enhanced repair of subchondral bone after treatment with BMP-2 muscle, with a significantly larger bone area compared to untreated defects. Gene activated muscle tissue grafts showed potential for osteochondral defect repair. There is room for improvement via the use of appropriate growth factor combinations.

Retracted: 3D Printing of Bilineage Constructive Biomaterials for Bone and Cartilage Regeneration

Owing to the different biological properties of articular cartilage and subchondral bone, it remains significant challenge to construct a bi‐lineage constructive scaffold. In this study, manganese (Mn)‐doped β‐TCP (Mn‐TCP) scaffolds with varied Mn contents are prepared by a 3D‐printing technology. The effects of Mn on the physicochemical properties, bioactivity, and corresponding mechanism for stimulating osteochondral regeneration are systematically investigated. The incorporation of Mn into β‐TCP lowers the lattices parameters and crystallization temperatures, but improves the scaffold density and compressive strength. The ionic products from Mn‐TCP significantly improve the proliferation of both rabbit chondrocytes and mesenchymal stem cells (rBMSCs), as well as promote the differentiation of chondrocytes and rBMSCs. The in vivo study shows that Mn‐TCP scaffolds distinctly improve the regeneration of subchondral bone and cartilage tissues as compared to TCP scaffolds, upon transplantation in rabbit osteochondral defects for 8 and 12 weeks. The mechanism is closely related to the Mn2+ ions significantly stimulated the proliferation and differentiation of chondrocytes through activating HIF pathway and protected chondrocytes from the inflammatory osteoarthritis environment by activating autophagy. These findings suggest that 3D‐printing of Mn‐containing scaffolds with improved physicochemical properties and bilineage bioactivities represents an intelligent strategy for regenerating osteochondral defects.

Mesenchymal stem cells with IGF-1 and TGF- β1 in laminin gel for osteochondral defects in rabbits

ObjectiveHealing of articular cartilage is still a challenge due to its limited potential to regenerate. In the present study, we evaluated allogenic bone marrow mesenchymal stem cells (BM-MSCs) alone or in combination with growth factors, insulin-like growth factor-1 (IGF-1) and transforming growth factor-β1 (TGF-β1) in laminin scaffolds for healing of osteochondral defects. DesignOsteochondral defects of 4mm (diameter) x 5mm (depth) were induced in the rabbit knee joints and treated with phosphate-buffered saline (PBS; control), BM-MSCs, BM-MSCs in laminin, BM-MSCs in laminin with IGF-1, or BM-MSCs in laminin with IGF-1 and TGF-β1 in 10 animals each. Gross, radiographic, scanning electron microscopic (SEM) and histologic examinations besides chondrocyte-specific genes expression by quantitative real time qPCR were carried out at 8 and 12 weeks. ResultsGross and SEM examination revealed superior morphology and surface architecture of the healing site in animals that received MSCs with IGF-1 or IGF-1 and TGF-β1. The application of laminin composites containing MSCs with IGF-1 and TGF-β1 significantly enhanced hyaline cartilage formation with improved cellular arrangement, proteoglycan deposition, clear tidemark zone and subchondral bone formation. However, regenerated tissue in defects that received only MSCs had poor tidemark zone and proteoglycans deposition Aggrecan and Coll2 expression was significantly higher in case of MSCs with growth factors. ConclusionThe treatment with BM-MSCs combined with IGF-1/TGF-β1 into laminin gel scaffold might enhance the restoration of hyaline cartilage in osteochondral defect.

Regeneration of the Osteochondral Defect by a Wollastonite and Macroporous Fibrin Biphasic Scaffold.

Osteochondral defect refers to the damage of cartilage as well as subchondral bone. Cartilage tissue engineering focusing on the regeneration of cartilage and disregarding the subchondral bone always leads to partial regeneration of the damage, resulting in poor mechanical and physiological properties. A scaffold suitable for in situ inductive regeneration of both types of tissues is urgently needed. In this study, a biphasic scaffold integrated by macro-porous fibrin and 3D-printed wollastonite (containing 8% MgSiO3 (CS-Mg8)) scaffolds, either preloaded with rabbit bone marrow mesenchymal stem cells (BMSCs) or not, were fabricated and used to repair osteochondral defects in vivo (full thickness osteochondral defects in rabbits, 4 mm in diameter and 4 mm in depth with bone marrow blood effusion). The fibrin scaffold had a pore size of 100-200 μm, and was degraded gradually and reached weight loss over 80% at 28 days. The presence of BMSCs could accelerate the degradation rate. BMSCs could well proliferate in the fibrin scaffold along with time prolongation. The CS-Mg8 scaffold possessed a regular structure of cross stacked CS-Mg8 rods, and was degraded rather slowly with a mass loss of 8.5% at 28 days. BMSCs adhered and showed well spreading on the CS-Mg8 scaffold, without apparent proliferation in vitro. In vivo transplantation of the biphasic scaffolds, either preloaded with BMSCs or not, could induce the regeneration of both cartilage and subchondral bone to a great extent. Loading of BMSCs enabled better regeneration of cartilage layer, leading to smoother macroscopic appearance, good integrity with surrounding tissue and tide mark formation. However, no significant difference in bone formation and in gene expression was found with and without BMSCs loading.

Evaluation of the effectiveness of a bMSC and BMP-2 polymeric trilayer system in cartilage repair

In this study a poly(lactide-co-glycolide) acid (PLGA) tri-layer scaffold is proposed for cartilage repair. The trilayer system consists of a base layer formed by a tablet of PLGA microspheres, a second layer composed of a microsphere suspension placed on top of the tablet, and the third layer, which constitutes an external electrospun PLGA thin polymeric membrane. Combinations of bone morphogenetic protein-2 (BMP-2) encapsulated in the microspheres of the suspension layer, and bone marrow mesenchymal stem cells (bMSC) seeded on the electrospun membrane, are evaluated by histologic analyses and immunohistochemistry in a critical size osteochondral defect in rabbits. Five experimental groups, including a control group (empty defect), a blank group (blank scaffold), a bMSC treated group, two groups treated with 2.5 μg or 8.5 μg of BMP-2 and another two groups implanted with bMSC-BMP-2 combination are evaluated. The repair area increases throughout the experimental time (24 weeks). The repair observed in the treated groups is statistically higher than in control and blank groups. However, the bMSC-BMP-2 combination does not enhance the BMP-2 response. In conclusion, BMP-2 and bMSC repaired effectively the osteochondral defect in the rabbits. The bMSC-BMP-2 combination did not produce synergism.

Preparation of a biphase composite scaffold and its application in tissue engineering for femoral osteochondral defects in rabbits.

Three-dimensional bioactive scaffolds are useful tools for stem cell implant in tissue-engineering. For chondral and subchondral repair, the chondroinductive and osteoinductive property of a scaffold is a major challenge. The scaffolds that aim to osteogenic differentiation have been well studied. However, cartilage cells can hardly be induced for osteogenesis, and monophase scaffolds cannot ideally repair both cartilage and subchondral defects at the same time. We developed a novel biphase composite scaffold and observe its application osteochondral defects. We combined the advantages of silk-fibroin/chitosan (SF/CS) scaffold in chondrogenic differentiation and the silk-fibroin/chitosan/nano-hydroxyapatite (SF/CS/nHA) scaffold in osteogenic differentiation and bone regeneration, and synthesized a SF/CS-SF/CS/nHA scaffold, which contained both the chondrocytic phase (SF/CS) and the osteoblastic phase (SF/CS/nHA). The biphase scaffold exhibited a porosity ratio around 90% and a water absorption ratio about 822%. A similar degradation property to traditional monophase scaffolds was observed. Bone mesenchymal stem cells (BMSCs) showed a good proliferation on this scaffold. Expression of two types of collagen was inducable for BMSCs on the scaffold. Neoformative extracellular matrix integrated with the scaffold was observed by the scanning electron microscope. When implanted in the lesion site in the rabbit femur with cartilage injury, mixing and filling function were exerted by the cell-scaffold constructs (CSCs). Micro-CT scanning revealed both chondral and subchondral layers were repaired. Moreover, type I and II collagens were both expressed in the implanted CSCs. Chondral and subchondral repair can be achieved using the biphase scaffold implant that permits both chondrogenesis and osteogenesis from BMSCs. This approach has the potential to be clinically used for tissue engineering implantation.

Experimental study on loading naringin composite scaffolds for repairing rabbit osteochondral defects

To investigate the performance of loading naringin composite scaffolds and its effects on repair of osteochondral defects. The loading naringin and unloading naringin sustained release microspheres were prepared by W/O/W method; with the materials of the attpulgite and the collagen type I, the loading naringin, unloading naringin, and loading transforming growth factor β 1 (TGF-β 1) osteochondral composite scaffolds were constructed respectively by "3 layers sandwich method". The effect of sustained-release of loading naringin microspheres, the morphology of the composite scaffolds, and the biocompatibility were evaluated respectively by releasing in vitro, scanning electron microscope, and cell counting kit 8. Forty Japanese white rabbits were randomly divided into groups A, B, C, and D, 10 rabbits each group. After a osteochondral defect of 4.5 mm in diameter and 4 mm in depth was made in the intercondylar fossa of two femurs. Defect was not repaired in group A (blank control), and defect was repaired with unloading naringin composite scaffolds (negative control group), loading naringin composite scaffolds (experimental group), and loading TGF-β 1 composite scaffolds (positive control group) in groups B, C, and D respectively. At 3 and 6 months after repair, the intercondylar fossa was harvested for the general, HE staining, and toluidine blue staining to observe the repair effect. Western blot was used to detect the expression of collagen type II in the new cartilage. Loading naringin microspheres had good effect of sustained-release; the osteochondral composite scaffolds had good porosity; the cell proliferation rate on loading naringin composite scaffold was increased significantly when compared with unloading naringin scaffold ( P<0.05). General observation revealed that defect range of groups C and D was reduced significantly when compared with groups A and B at 3 months after repair; at 6 months after repair, defects of group C were covered by new cartilage, and new cartilage well integrated with the adjacent cartilage in group D. The results of histological staining revealed that defects were filled with a small amount of fibrous tissue in groups A and B, and a small amount of new cartilage in groups C and D at 3 months after repair; new cartilage of groups C and D was similar to normal cartilage, but defects were filled with a large amount of fibrous tissue in groups A and B at 6 months after repair. The expression of collagen type II in groups C and D was significantly higher than that in groups A and B ( P<0.05), but no significant difference was found between groups C and D ( P>0.05). Loading naringin composite scaffolds have good biocompatibility and effect in repair of rabbit articular osteochondral defects.

In vivo evaluation of porous hydrogel pins to fill osteochondral defects in rabbits

ObjectiveThis experimental study aimed to evaluate the biological performance of poly (l-co-D, l-lactic acid)-co-trimetilene carbonate/poly (vinyl alcohol) (PLDLA-co TMC/PVA), hydrogel scaffolds, as an implant in the filling (and not in the repair) of osteochondral defects in New Zealand rabbits, assessing the influence of the material in tissue protection in vivo. MethodsTwelve rabbits were divided into groups of nine and 16 weeks. In each animal, an osteochondral defect was created in both medial femoral condyles. In one knee, a hydrogel scaffold was implanted (pin group) and in the other, the defect was maintained (control group). A histological analysis of the material was performed after euthanasia. ResultsThe condyles of the pin group showed no inflammatory reaction and were surrounded by a fibrous capsule. The control group presented higher bone growth in the areas of the defect, but with disorganized articular cartilage, evident fibrosis, bone exposure, atrophy, and proliferation of synovial membrane. ConclusionThe hydrogel pins are promising in filling osteochondral defects, generally do not cause inflammatory reactions, and are not effective in the repair of osteochondral defects.

Comparison of 2 Different Formulations of Artificial Bone for a Hybrid Implant With a Tissue-Engineered Construct Derived From Synovial Mesenchymal Stem Cells: A Study Using a Rabbit Osteochondral Defect Model

Background: Previously, we developed a hybrid implant composed of hydroxyapatite (HA)–based artificial bone coupled with a mesenchymal stem cell (MSC)–based scaffold-free tissue-engineered construct (TEC) and demonstrated its feasibility for osteochondral repair. Beta-tricalcium phosphate (βTCP) may be a promising alternative to HA, as it is a highly biocompatible material and is resorbed more rapidly than HA in vivo. Hypothesis: A βTCP-based hybrid TEC implant will exhibit superior osteochondral repair when directly compared with an HA-based hybrid implant, as tested using a rabbit osteochondral defect model. Study Design: Controlled laboratory study. Methods: Osteochondral defects were created in the femoral groove of skeletally mature rabbits. The TEC and artificial bone, using either HA or βTCP with the same porosities and similar mechanical properties, were hybridized and then implanted in the defects. A histological evaluation and microindentation testing were performed for the assessment of repair tissue. Results: Osteochondral defects treated with the TEC/βTCP implants showed more rapid subchondral bone repair at 1 month, but the cartilaginous tissue deteriorated over time out to 6 months after implantation. Osteochondral defects treated with the TEC/HA implants maintained good histological quality out to 6 months after implantation and also exhibited better biomechanical properties at 6 months as compared with the TEC/βTCP implants. Conclusion: Contrary to our hypothesis, the TEC/HA hybrid implant facilitated better osteochondral repair than did the TEC/βTCP implant. The results of the present study suggest the importance of a stable restoration of subchondral bone for long-term effective osteochondral repair rather than rapid remodeling of subchondral bone. Clinical Relevance: This study contributes to the future selection of suitable materials for patients with osteochondral lesions.

Effects of a cell-free method using collagen vitrigel incorporating TGF-β1 on articular cartilage repair in a rabbit osteochondral defect model.

We studied the ability of collagen vitrigel material to repair cartilage in vivo when used alone or with transforming growth factor-β (TGF-β). We measured the time course and quantity of TGF-β1 released from the collagen vitrigel in vitro to quantify the controlled release of TGF-β1. Over 14 days, 0.91 ng of TGF-β was released from the collagen vitrigel. Osteochondral defects were made in the femoral trochlear groove in 36 Japanese white rabbits, which were divided into three groups: untreated group (group A), collagen vitrigel-implanted group (group B), and TGF-β1-incorporated collagen vitrigel-implanted group (group C). The weight distribution ratio between the affected and unaffected limbs served as an indicator of pain. Animals were sacrificed at 4 and 12 weeks after surgery, and their tissues were assessed histologically. The weight distribution ratio increased in all groups and did not differ significantly between groups at 12 weeks. Group A needed 6 weeks to attain maximum improvement, and groups B and C showed near-maximum improvement at 4 and 2 weeks, respectively. The International Cartilage Repair Society II score improved significantly in group C relative to the other groups. These findings suggest that sustained, slow release of TGF-β caused early pain mitigation and cartilage repair. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2592-2602, 2017.