Optical imaging of articular cartilage degeneration using near-infrared dipicolylamine probes

Articular cartilage is the hydrated tissue that lines the ends of long bones in load bearing joints and provides joints with a smooth, nearly frictionless gliding surface. However, the deterioration of articular cartilage occurs in the early stages of osteoarthritis (OA) and is clinically and radiographically silent. Here two cationic near infrared fluorescent (NIRF) dipicolylamine (DPA) probes, Cy5-DPA-Zn and Cy7-DPA-Zn, were prepared for cartilage degeneration imaging and OA early detection through binding to the anionic glycosaminoglycans (GAGs). The feasibility of NIRF dye labeled DPA-Zn probes for cartilage degeneration imaging was examined ex vivo and in vivo. The ex vivo studies showed that Cy5-DPA-Zn and Cy7-DPA-Zn not only showed the high uptake and electrostatic attractive binding to cartilage, but also sensitively reflected the change of GAGs contents. In vivo imaging study further indicated that Cy5-DPA-Zn demonstrated higher uptake and retention in young mice (high GAGs) than old mice (low GAGs) when administrated via local injection in mouse knee joints. More importantly, Cy5-DPA-Zn showed dramatic higher signals in sham joint (high GAGs) than OA side (low GAGs), through sensitive reflecting the change of GAGs in the surgical induced OA models. In summary, Cy5-DPA-Zn provides promising visual detection for early cartilage pathological degeneration in living subjects.     

SOX trio-co-transduced adipose stem cells in fibrin gel to enhance cartilage repair and delay the progression of osteoarthritis in the rat

The aim of this study was to test the hypotheses that retroviral gene transfer of SOX trio enhances the in vitro chondrogenic differentiation of ASCs, and that SOX trio-co-transduced ASCs in fibrin gel promote the healing of osteochondral defects, and arrest the progression of surgically-induced osteoarthritis in a rat model. ASCs isolated from inguinal fat in rats were transduced with SOX trio genes using retrovirus, and further cultured in vitro in pellets for 21 days, then analyzed for gene and protein expression of SOX trio and chondrogenic markers. SOX trio-co-transduced ASCs in fibrin gel were implanted on the osteochondral defect created in the patellar groove of the distal femur, and also injected into the knee joints of rats with surgically-induced osteoarthritis. Rats were sacrificed after 8 weeks, and analyzed grossly and microscopically. After 21 days, ASCs transduced with SOX-5, -6, or -9 had hundreds-fold greater gene expression of each gene compared with the control with the SOX protein expression matching gene expression. SOX trio-co-transduction significantly increased GAG contents as well as type II collagen gene and protein expression. ASCs co-transduced with SOX trio significantly promoted the in vivo cartilage healing in osteochondral defect model, and prevented the progression of degenerative changes in surgically-induced osteoarthritis.     

Modulation of chondrocyte functions and stiffness-dependent cartilage repair using an injectable enzymatically crosslinked hydrogel with tunable mechanical properties

We developed an injectable hydrogel system to evaluate the effect of hydrogel stiffness on chondrocyte cellular functions in a three-dimensional (3D) environment and its subsequent influence on ectopic cartilage formation and early-stage osteochondral defect repair in a rabbit model. The hydrogels, composed of gelatin-hydroxyphenylpropionic acid (Gtn-HPA) conjugate, were formed using oxidative coupling of HPA moieties catalyzed by hydrogen peroxide (H₂O₂) and horseradish peroxidase (HRP). The storage modulus (G′) of the hydrogels, which was tunable by changing the H₂O₂ and Gtn-HPA concentrations, ranged from 570 Pa to 2750 Pa. It was found that the cellular functions of chondrocytes encapsulated in hydrogels, including cell proliferation, biosynthesis of collagen and sulfated glycosaminoglycans (sGAG), as well as gene expression of type I (Col-I) and type II collagen (Col-II), were strongly affected by the stiffness of the hydrogels. Of note, chondrocytes cultured within the Gtn-HPA hydrogel of medium stiffness (G′ = 1000 Pa) produced highest level of sGAG production, as well as highest ratio of Col-II to Col-I gene expression among the Gtn-HPA hydrogels of different stiffness. Consistent with the results from in vitro and in vivo ectopic cartilage formation, osteochondral defect repair in a rabbit model showed stiffness-dependent tissue repair, with defects implanted with chondrocytes in hydrogels of medium stiffness having markedly more hyaline cartilage formation, smoother surface and better integration with adjacent cartilage, compared to defects treated with hydrogels of low or high stiffness. These results suggest that the tunable stiffness of Gtn-HPA hydrogels modulates chondrocyte cellular functions, and has a dramatic impact on cartilage tissue histogenesis and repair.     

Mechano growth factor (MGF) and transforming growth factor (TGF)-β3 functionalized silk scaffolds enhance articular hyaline cartilage regeneration in rabbit model

Damaged cartilage has poor self-healing ability and usually progresses to scar or fibrocartilaginous tissue, and finally degenerates to osteoarthritis (OA). Here we demonstrated that one of alternative isoforms of IGF-1, mechano growth factor (MGF) acted synergistically with transforming growth factor β3 (TGF-β3) embedded in silk fibroin scaffolds to induce chemotactic homing and chondrogenic differentiation of mesenchymal stem cells (MSCs). Combination of MGF and TGF-β3 significantly increased cell recruitment up to 1.8 times and 2 times higher than TGF-β3 did in vitro and in vivo. Moreover, MGF increased Collagen II and aggrecan secretion of TGF-β3 induced hMSCs chondrogenesis, but decreased Collagen I in vitro. Silk fibroin (SF) scaffolds have been widely used for tissue engineering, and we showed that methanol treated pured SF scaffolds were porous, similar to compressive module of native cartilage, slow degradation rate and excellent drug released curves. At 7days after subcutaneous implantation, TGF-β3 and MGF functionalized silk fibroin scaffolds (STM) recruited more CD29+/CD44 + cells (P < 0.05). Similarly, more cartilage-like extracellular matrix and less fibrillar collagen were detected in STM scaffolds than that in TGF-β3 modified scaffolds (ST) at 2 months after subcutaneous implantation. When implanted into articular joints in a rabbit osteochondral defect model, STM scaffolds showed the best integration into host tissues, similar architecture and collagen organization to native hyaline cartilage, as evidenced by immunostaining of aggrecan, collagen II and collagen I, as well as Safranin O and Masson's trichrome staining, and histological evalution based on the modified O'Driscoll histological scoring system (P < 0.05), indicating that MGF and TGF-β3 might be a better candidate for cartilage regeneration. This study demonstrated that TGF-β3 and MGF functionalized silk fibroin scaffolds enhanced endogenous stem cell recruitment and facilitated in situ articular cartilage regeneration, thus providing a novel strategy for cartilage repair.     

Articular chondrocytes and mesenchymal stem cells seeded on biodegradable scaffolds for the repair of cartilage in a rat osteochondral defect model

This work investigated the ability of co-cultures of articular chondrocytes and mesenchymal stem cells (MSCs) to repair articular cartilage in osteochondral defects. Bovine articular chondrocytes and rat MSCs were seeded in isolation or in co-culture onto electrospun poly(?-caprolactone) (PCL) scaffolds and implanted into an osteochondral defect in the trochlear groove of 12-week old Lewis rats. Additionally, a blank PCL scaffold and untreated defect were investigated. After 12 weeks, the extent of cartilage repair was analyzed through histological analysis, and the extent of bone healing was assessed by quantifying the total volume of mineralized bone in the defect through microcomputed tomography. Histological analysis revealed that the articular chondrocytes and co-cultures led to repair tissue that consisted of more hyaline-like cartilage tissue that was thicker and possessed more intense Safranin O staining. The MSC, blank PCL scaffold, and empty treatment groups generally led to the formation of fibrocartilage repair tissue. Microcomputed tomography revealed that while there was an equivalent amount of mineralized bone formation in the MSC, blank PCL, and empty treatment groups, the defects treated with chondrocytes or co-cultures had negligible mineralized bone formation. Overall, even with a reduced number of chondrocytes, co-cultures led to an equal level of cartilage repair compared to the chondrocyte samples, thus demonstrating the potential for the use of co-cultures of articular chondrocytes and MSCs for the in vivo repair of cartilage defects.     

Combined use of chondroitinase-ABC,TGF-β1, and collagen crosslinking agent lysyl oxidase to engineer functional neotissues for fibrocartilage repair

Patients suffering from damaged or diseased fibrocartilages currently have no effective long-term treatment options. Despite their potential, engineered tissues suffer from inferior biomechanical integrity and an inability to integrate in vivo. The present study identifies a treatment regimen (including the biophysical agent chondroitinase-ABC, the biochemical agent TGF-β1, and the collagen crosslinking agent lysyl oxidase) to prime highly cellularized, scaffold-free neofibrocartilage implants, effecting continued improvement in vivo. We show these agents drive in vitro neofibrocartilage matrix maturation toward synergistically enhanced Young's modulus and ultimate tensile strength values, which were increased 245% and 186%, respectively, over controls. Furthermore, an in vitro fibrocartilage defect model found this treatment regimen to significantly increase the integration tensile properties between treated neofibrocartilage and native tissue. Through translating this technology to an in vivo fibrocartilage defect model, our results indicate, for the first time, that a pre-treatment can prime neofibrocartilage for significantly enhanced integration potential in vivo, with interfacial tensile stiffness and strength increasing by 730% and 745%, respectively, compared to integration values achieved in vitro. Our results suggest that specifically targeting collagen assembly and organization is a powerful means to augment overall neotissue mechanics and integration potential toward improved clinical feasibility.     

Early Cartilage Degeneration in a Rat Experimental Model of Developmental Dysplasia of the Hip

Osteoarthritis (OA) is a common long-term complication of developmental dysplasia of the hip (DDH) that is associated with a higher incidence of OA. In addition, the age of onset of OA in DDH patients is significantly younger than in the general population. In order to investigate the early degeneration in DDH cartilage, we used a rat DDH model that was established by the straight-leg swaddling position. The hips were isolated from the DDH model rats and an untreated control group at postnatal weeks 2, 4, 6, and 8. Histology and proteoglycan levels were observed in articular cartilage using Safranin O staining. Biomarkers of cartilage degeneration, including type X collagen and matrix metalloproteinase (MMP)-13, were assessed using immunohistochemistry and quantitative real-time polymerase chain reaction. In addition, expressions of ADAMTS-4 and ADAMTS-5 were studied using quantitative real-time polymerase chain reaction at different ages. DDH rats showed decreased proteoglycans and derangement of chondrocytes when compared with the control group. Collagen X and MMP-13 expressions were higher in the superficial zone of DDH rats than in that of controls (p < 0.05), and the increase was age-dependent. mRNA expression of Collagen X and MMP-13 showed similar results (p < 0.05). A significant increase in mRNA expression of ADAMTS-5 was found in the DDH model cartilage at 8 weeks (p < 0.05). However, no change was observed in ADAMTS-4 expression. This study shows that degenerative cartilage changes occur at an early stage in the rat DDH model and become aggravated with age.     

The impact of PLGA scaffold orientation on in vitro cartilage regeneration

The success of in vitro cartilage regeneration provides a promising approach for cartilage repair. However, the currently engineered cartilage in vitro is unsatisfactory for clinical application due to non-homogeneous structure, inadequate thickness, and poor mechanical property. It has been widely reported that orientation of scaffolds can promote cell migration and thus probably contributes to improving tissue regeneration. This study explored the impact of microtubular oriented scaffold on in vitro cartilage regeneration. Porcine articular chondrocytes were seeded into microtubule-oriented PLGA scaffolds and non-oriented scaffolds respectively. A long-term in vitro culture followed by a long-term in vivo implantation was performed to evaluate the influence of scaffold orientation on cartilage regeneration. The current results showed that the oriented scaffolds could efficiently promote cell migration towards the inner region of the constructs. After 12 weeks of in vitro culture, the chondrocyte-scaffold constructs in the oriented group formed thicker cartilage with more homogeneous structure, stronger mechanical property, and higher cartilage matrix content compared to the non-oriented group. Furthermore, the in vitro engineered cartilage based on oriented scaffolds showed better cartilage formation in terms of size, wet weight, and homogeneity after 12-week in vivo implantation in nude mice. These results indicated that the longitudinal microtubular orientation of scaffolds can efficiently improve the structure and function of in vitro engineered cartilage.     

Synthesis and characterization of a lubricin mimic (mLub) to reduce friction and adhesion on the articular cartilage surface

The lubricating proteoglycan, lubricin, facilitates the remarkable low friction and wear properties of articular cartilage in the synovial joints of the body. Lubricin lines the joint surfaces and plays a protective role as a boundary lubricant in sliding contact; decreased expression of lubricin is associated with cartilage degradation and the pathogenesis of osteoarthritis. An unmet need for early osteoarthritis treatment is the development of therapeutic molecules that mimic lubricin function and yet are also resistant to enzymatic degradation common in the damaged joint. Here, we engineered a lubricin mimic (mLub) that is less susceptible to enzymatic degradation and binds to the articular surface to reduce friction. mLub was synthesized using a chondroitin sulfate backbone with type II collagen and hyaluronic acid (HA) binding peptides to promote interaction with the articular surface and synovial fluid constituents. In vitro and in vivo characterization confirmed the binding ability of mLub to isolated type II collagen and HA, and to the cartilage surface. Following trypsin treatment to the cartilage surface, application of mLub, in combination with purified or commercially available hyaluronan, reduced the coefficient of friction, and adhesion, to control levels as assessed over macro-to micro-scales by rheometry and atomic force microscopy. In vivo studies demonstrate an mLub residency time of less than 1 week. Enhanced lubrication by mLub reduces surface friction and adhesion, which may suppress the progression of degradation and cartilage loss in the joint. mLub therefore shows potential for treatment in early osteoarthritis following injury.     

An arthroscopic device to assess articular cartilage defects and treatment with a hydrogel

The hydraulic resistance R across osteochondral tissue, especially articular cartilage, decreases with degeneration and erosion. Clinically useful measures to quantify and diagnose the extent of cartilage degeneration and efficacy of repair strategies, especially with regard to pressure maintenance, are still developing. The hypothesis of this study was that hydraulic resistance provides a quantitative measure of osteochondral tissue that could be used to evaluate the state of cartilage damage and repair. The aims were to (1) develop a device to measure R in an arthroscopic setting, (2) determine whether the device could detect differences in R for cartilage, an osteochondral defect, and cartilage treated using a hydrogel ex vivo, and (3) determine how quickly such differences could be discerned. The apparent hydraulic resistance of defect samples was ~35% less than intact cartilage controls, while the resistance of hydrogel-filled groups was not statistically different than controls, suggesting some restoration of fluid pressurization in the defect region by the hydrogel. Differences in hydraulic resistance between control and defect groups were apparent after 4 s. The results indicate that the measurement of R is feasible for rapid and quantitative functional assessment of the extent of osteochondral defects and repair. The arthroscopic compatibility of the device demonstrates the potential for this measurement to be made in a clinical setting.     

Radially oriented collagen scaffold with SDF-1 promotes osteochondral repair by facilitating cell homing

The migration of cells from the side and the bottom of the defect is important in osteochondral defect healing. Here, we designed a novel collagen scaffold that possessed channels in both the horizontal and the vertical directions, along with stromal cell-derived factor-1 (SDF-1) to enhance osteochondral regeneration by facilitating cell homing. Firstly we fabricated the radially oriented and random collagen scaffolds, then tested their properties. The radially oriented collagen scaffold had better mechanical properties than the random scaffold, but both supported cell proliferation well. Then we measured the migration of BMSCs in the scaffolds in vitro. The radially oriented collagen scaffold effectively promoted their migration, and this effect was further facilitated by addition of SDF-1. Moreover, we created osteochondral defects in rabbits, and implanted them with random or oriented collagen scaffolds with or without SDF-1, and evaluated cartilage and subchondral bone regeneration at 6 and 12 weeks after surgery. Cartilage regeneration with both the radially oriented scaffold and SDF-1 effectively promoted repair of the cartilage defect. Our results confirmed that the implantation of the radially oriented channel collagen scaffold with SDF-1 could be a promising strategy for osteochondral repair.     

The effect of dose on rhBMP-2 signaling,delivered via collagen sponge,on osteoclast activation and in vivo bone resorption

While recombinant human bone morphogenetic protein (rhBMP)-2-based bone therapy presents potential osteoinductivity, it also leads concern due to transient osteoclast activation during early healing periods, ultimately limiting its clinical use. Therefore, we investigated in vivo and in vitro rhBMP-2 signaling which mediates early bone resorbing effect, depending on the dose, and attempted to inhibit this resorption phenomenon using NFAT inhibitor as a target molecule. High-dose of rhBMP-2 (20 μg/defect) enhanced osteoclast activation and the expression of bone resorption markers, compared to low dose (5 μg/defect) at one week after surgery in collagen sponge-delivered rat calvarial defect models. Interestingly, this trend was also observed in the expression of bone formation markers. In particular, rhBMP-2 upregulated RANKL expression, while it downregulated osteoprotegerin (OPG) expression, resulting in a dose-dependent increase in the ratio of RANKL to OPG. NFAT inhibitor (150 μm) treatment in vivo suppressed the high-dose effect of rhBMP-2 on both resorption and formation. In vitro results of rhBMP-2 signaling and NFAT inhibitor effects in rat mesenchymal stem cells showed similar trends as in vivo results. Microcomputer tomography-based evaluation at 4 weeks showed that combined treatment of NFAT inhibitor with 20 μg rhBMP-2 in vivo increased bone volume (BV) more than 20 μg rhBMP-2 alone, which showed little difference in BV compared to 5 μg of rhBMP-2. These results demonstrated that rhBMP-2 implantation concurrently signalized into enhanced osteoclastogenesis and osteoblastogenesis in vivo, dose-dependently. Ratio of RANKL/OPG might be an index for early bone resorbing activity of implanted rhBMP-2. A local cocktail treatment of NFAT inhibitor and high-dose rhBMP-2 might be an alternative to overcome early bone resorbing effects, thereby accelerating bone formation.     

Astragaloside inhibits IL-1β-induced inflammatory response in human osteoarthritis chondrocytes and ameliorates the progression of osteoarthritis in mice

Abstract

Background: Osteoarthritis (OA) is a chronic joint-degeneration disease and accounts for the most frequent arthritis in aging people. OA is characterized by the degeneration of articular cartilage, subchondral bone sclerosis and synovitis. Inflammation as an important role in OA progression, in that anti-inflammatory agents could effectively inhibit the development of OA with minimal side effects, therefore developing a nature anti-inflammatory compound will be a promising therapy for treating OA.

Methods: We treated patient-derived chondrocytes and mouse models of OA with astragaloside, an effective component of astragalus membranaceus, and measured its effect on pro-inflammatory cytokines and OA progression in mice.

Results: In vitro, astragaloside induced a dose-dependent inhibition of IL-1β-induced the production of inflammatory factors, including interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), nitric oxide (NO), prostaglandin E2 (PGE2), expression of MMP 13 and ADAMTS-5, and the activation of NF-κB signaling. In vivo, astragaloside ameliorate the degeneration of cartilage in mouse model of OA.

Conclusion: Astragaloside potentially serve as a promising and effective therapeutic agent for treating OA patients.     

Release behavior and intra-articular biocompatibility of celecoxib-loaded acetyl-capped PCLA-PEG-PCLA thermogels

In this study, we investigated the in vitro and in vivo properties and performance of a celecoxib-loaded hydrogel based on a fully acetyl-capped PCLA-PEG-PCLA triblock copolymer. Blends of different compositions of celocoxib, a drug used for pain management in osteoarthritis, and the acetyl-capped PCLA-PEG-PCLA triblock copolymer were mixed with buffer to yield temperature-responsive gelling systems. These systems containing up to 50 mg celecoxib/g gel, were sols at room temperature and converted into immobile gels at 37 °C. In vitro, release of celecoxib started after a ∼10-day lag phase followed by a sustained release of ∼90 days. The release was proven to be mediated by polymer dissolution from the gels. In vivo (subcutaneous injection in rats) experiments showed an initial celecoxib release of ∼30% during the first 3 days followed by a sustained release of celecoxib for 4–8 weeks. The absence of a lag phase and the faster release seen in vivo were likely due to the enhanced celecoxib solubility in biological fluids and active degradation of the gel by macrophages. Finally, intra-articular biocompatibility of the 50 mg/g celecoxib-loaded gel was demonstrated using μCT-scanning and histology, where no cartilage or bone changes were observed following injection into the knee joints of healthy rats. In conclusion, this study shows that celecoxib-loaded acetyl-capped PCLA-PEG-PCLA hydrogels form a safe drug delivery platform for sustained intra-articular release.     

MiR-671 ameliorates the progression of osteoarthritis in vitro and in vivo

ObjectivesExpression of miR-671 was reported to be downregulated in articular cartilage of patients with OA compared to healthy individuals, indicating it may serve as potential biomarker for OA. However, the mechanism by which miR-671 regulates the progression of OA remains unclear. Here, we aimed to investigate the role of miR-671 in cartilage from patients with OA.MethodsThe expression of miR-671 and inflammation mediators in cartilage from patients with OA was analyzed by RT-PCR. In vitro, chondrocytes CHON-001 were stimulated with IL-1β for 24 h for OA model establishment. Protein expression of MMP-13, aggrecan, and collagen II was measured by western blot. In vivo, the severity of OA in mice was determined by histological analysis.ResultsWe found that the level of miR-671 was downregulated in OA tissues, plasma and IL-1β treated CHON-001 cells, compared with control. MiR-671 mimics ameliorated IL-1β-induced proliferation inhibition and apoptosis stimulation, as well as decreased protein levels of collagen II and aggrecan in CHON-001 cells. In vivo study showed miR-671 mimics alleviated the progression of OA in mice.ConclusionThese results indicated miR-671 play an important role during the pathogenesis of OA. Therefore, miR-671 may serve as a potential therapeutic target for the treatment of OA.     

Intra-articular delivery of kartogenin-conjugated chitosan nano/microparticles for cartilage regeneration

We developed an intra-articular (IA) drug delivery system to treat osteoarthritis (OA) that consisted of kartogenin conjugated chitosan (CHI-KGN). Kartogenin, which promotes the selective differentiation of mesenchymal stem cells (MSCs) into chondrocytes, was conjugated with low-molecular-weight chitosan (LMWCS) and medium-molecular-weight chitosan (MMWCS) by covalent coupling of kartogenin to each chitosan using an ethyl(dimethylaminopropyl) carbodiimide (EDC)/N-hydroxysuccinimide (NHS) catalyst. Nanoparticles (NPs, 150 ± 39 nm) or microparticles (MPs, 1.8 ± 0.54 μm) were fabricated from kartogenin conjugated-LMWCS and –MMWCS, respectively, by an ionic gelation using tripolyphosphate (TPP). The in vitro release profiles of kartogenin from the particles showed sustained release for 7 weeks. When the effects of the CHI-KGN NPs or CHI-KGN MPs were evaluated on the in vitro chondrogenic differentiation of human bone marrow MSCs (hBMMSCs), the CHI-KGN NPs and CHI-KGN MPs induced higher expression of chondrogenic markers from cultured hBMMSCs than unconjugated kartogenin. In particular, hBMMSCs treated with CHI-KGN NPs exhibited more distinct chondrogenic properties in the long-term pellet cultures than those treated with CHI-KGN MPs. The in vivo therapeutic effects of CHI-KGN NPs or CHI-KGN MPs were investigated using a surgically-induced OA model in rats. The CHI-KGN MPs showed longer retention time in the knee joint than the CHI-KGN NPs after IA injection in OA rats. The rats treated with CHI-KGN NPs or CHI-KGN MPs by IA injection showed much less degenerative changes than untreated control or rats treated with unconjugated kartogenin. In conclusion, CHI-KGN NPs or CHI-KGN MPs can be useful polymer-drug conjugates as an IA drug delivery system to treat OA.     

Inhibition of blood vessel formation by a chondrocyte-derived extracellular matrix

In this study, the chondrocyte-derived extracellular matrix (CECM) was evaluated for its activity to inhibit vessel invasion in vitro and in vivo. Human umbilical vein endothelial cells (HUVECs) and rabbit chondrocytes were plated on a bio-membrane made of CECM or human amniotic membrane (HAM). The adhesion, proliferation, and tube formation activity of HUVECs and chondrocytes were examined. The CECM and HAM powders were then mixed individually in Matrigel and injected subcutaneously into nude mice to examine vessel invasion in vivo after 1 week. Finally, a rabbit model of corneal neovascularization (NV) was induced by 3-point sutures in the upper cornea, and CECM and HAM membranes were implanted onto the corneal surface at day 5 after suture injury. The rabbits were sacrificed at 7 days after transplantation and the histopathological analysis was performed. The adhesion and proliferation of HUVECs were more efficient on the HAM than on the CECM membrane. However, chondrocytes on each membrane showed an opposite result being more efficient on the CECM membrane. The vessel invasion in vivo also occurred more deeply and intensively in Matrigel containing HAM than in the one containing CECM. In the rabbit NV model, CECM efficiently inhibited the neovessels formation and histological remodeling in the injured cornea. In summary, our findings suggest that CECM, an integral cartilage ECM composite, shows an inhibitory effect on vessel invasion both in vitro and in vivo, and could be a useful tool in a variety of biological and therapeutic applications including the prevention of neovascularization after cornea injury.     

Intra-articular injection of human synovium-derived mesenchymal stem cells in beagles with surgery-induced osteoarthritis

BackgroundRecently, cell-based tissue engineering approaches using mesenchymal stem cells (MSCs) have been used to treat osteoarthritis (OA). However, the efficacy of human synovium-derived MSCs (hSD-MSCs) has not yet been tested in a canine model of OA. The purpose of this study was to investigate the therapeutic effects of intra-articular hSD-MSC injections in a canine OA model.MethodsSixty beagles underwent surgical manipulation to induce OA and received intra-articular injection 4 weeks after surgery. The dogs were divided into five groups (n = 12) according to the injection material: G1, sham group; G2, control group injected with phosphate-buffered saline; G3, G4, and G5, experimental groups injected with different hSD-MSC dosages (G3, 2.4 × 10⁶ cells; G4, 4.8 × 10⁶ cells; G5, 9.6 × 10⁶ cells). Magnetic resonance imaging (MRI) and histopathological and immunohistochemical examinations were performed 6 and 24 weeks after injection.ResultsMRI revealed significant improvements in synovitis 24 weeks after injection in the hSD-MSC-injected groups (G3–G5). Histopathologic analyses showed that cartilage structure and proteoglycan staining were also significantly improved in these groups (G3–G5) 6 weeks after injection and improved further after 24 weeks. Immunohistochemical analysis revealed significant differences in the levels of collagen types I and II between the hSD-injected groups (G3–G5), indicating a similar extracellular matrix (ECM) composition to naïve articular cartilage.ConclusionOur study demonstrated for the first time that intra-articular hSD-MSC injection ameliorates the progression of canine OA by restoring cartilage, promoting ECM synthesis, and inhibiting the inflammatory response.