The origin, roles and fate of progenitor cells forming synovial joints during limb skeletogenesis remain largely unclear. Here we produced prenatal and postnatal genetic cell fate-maps by mating ...ROSA-LacZ-reporter mice with mice expressing Cre-recombinase at prospective joint sites under the control of Gdf5 regulatory sequences (Gdf5-Cre). Reporter-expressing cells initially constituted the interzone, a compact mesenchymal structure representing the first overt sign of joint formation, and displayed a gradient-like distribution along the ventral-to-dorsal axis. The cells expressed genes such as Wnt9a, Erg and collagen IIA, remained predominant in the joint-forming sites over time, gave rise to articular cartilage, synovial lining and other joint tissues, but contributed little if any to underlying growth plate cartilage and shaft. To study their developmental properties more directly, we isolated the joint-forming cells from prospective autopod joint sites using a novel microsurgical procedure and tested them in vitro. The cells displayed a propensity to undergo chondrogenesis that was enhanced by treatment with exogenous rGdf5 but blocked by Wnt9a over-expression. To test roles for such Wnt-mediated anti-chondrogenic capacity in vivo, we created conditional mutants deficient in Wnt/β-catenin signaling using Col2-Cre or Gdf5-Cre. Synovial joints did form in both mutants; however, the joints displayed a defective flat cell layer normally abutting the synovial cavity and expressed markedly reduced levels of lubricin. In sum, our data indicate that cells present at prospective joint sites and expressing Gdf5 constitute a distinct cohort of progenitor cells responsible for limb joint formation. The cells appear to be patterned along specific limb symmetry axes and rely on local signaling tools to make distinct contributions to joint formation.
Dalbavancin is an intravenous lipoglycopeptide with activity against Gram-positive pathogens and an MIC90 for Staphylococcus aureus of 0.06 μg/ml. With a terminal half-life of >14 days, dosing ...regimens with infrequent parenteral administration become available to treat infectious diseases such as osteomyelitis and endocarditis that otherwise require daily dosing for many weeks. In order to support a rationale for these novel regimens, the pharmacokinetics over an extended dosing interval and the distribution of dalbavancin into bone and articular tissue were studied in two phase I trials and pharmacokinetic modeling was performed. Intravenous administration of 1,000 mg of dalbavancin on day 1 followed by 500 mg weekly for seven additional weeks was well tolerated and did not demonstrate evidence of drug accumulation. In a separate study, dalbavancin concentrations in cortical bone 12 h after infusion of a single 1,000-mg intravenous infusion were 6.3 μg/g and 2 weeks later were 4.1 μg/g. A two-dose, once-weekly regimen that would provide tissue exposure over the dalbavancin MIC for Staphylococcus aureus for 8 weeks, maximizing the initial exposure to treatment while minimizing the frequency of intravenous therapy, is proposed.
Articular cartilage defects are difficult to treat, but drug-loaded tissue engineering scaffolds provide a possible treatment option for these types of injuries.
In this study, we designed a ...bioactive resveratrol-PLA-gelatin porous nano-scaffold using electrospinning, freeze drying, and uniform dispersion techniques to repair articular cartilage defects, and then investigated the possible mechanism behind the successful repair.
We established an articular cartilage defect rat model with a 2 mm diameter wound in the middle of the knee joint femoral condyle non-weight-bearing area, with a depth reaching the full thickness of the subchondral bone. Postmodel specimens and micro computed tomography (CT) were used to observe any macroscopic morphological changes in the articular cartilage and subchondral bone, whereas multiple staining methods were used to observe all microcosmic morphological changes. Gross scores and Mankin scores were used to evaluate the repair condition. Immunohistochemical staining was employed to detect protein expression.
When the repair included the resveratrol-PLA-gelatin porous nano-scaffold, the repaired cartilage and subchondral bone were in better condition. The expression levels of SIRT1, type II collagen, and PI3K/AKT signaling pathway-related proteins (AKT, VEGF, PTEN, Caspase 9, and MMP13) changed significantly. The expression levels of SIRT1,AKT and type II collagen proteins increased significantly, while the expression levels of VEGF, PTEN, Caspase9 and MMP13 proteins decreased significantly compared with the repair included blank porous PLA-gelatin nano-scaffold and without scaffold.
We designed a bioactive resveratrol-PLA-gelatin porous nano-scaffold with better performance, which promoted the repair of cartilage injury as a whole, and explained its possible mechanism in accelerating cartilage repair via the PI3K/AKT signaling pathway.
Articular cartilage injuries are a common source of joint pain and dysfunction. We hypothesized that pulsed electromagnetic fields (PEMFs) would improve growth and healing of tissue‐engineered ...cartilage grafts in a direction‐dependent manner. PEMF stimulation of engineered cartilage constructs was first evaluated in vitro using passaged adult canine chondrocytes embedded in an agarose hydrogel scaffold. PEMF coils oriented parallel to the articular surface induced superior repair stiffness compared to both perpendicular PEMF (p = .026) and control (p = .012). This was correlated with increased glycosaminoglycan deposition in both parallel and perpendicular PEMF orientations compared to control (p = .010 and .028, respectively). Following in vitro optimization, the potential clinical translation of PEMF was evaluated in a preliminary in vivo preclinical adult canine model. Engineered osteochondral constructs (∅ 6 mm × 6 mm thick, devitalized bone base) were cultured to maturity and implanted into focal defects created in the stifle (knee) joint. To assess expedited early repair, animals were assessed after a 3‐month recovery period, with microfracture repairs serving as an additional clinical control. In vivo, PEMF led to a greater likelihood of normal chondrocyte (odds ratio OR: 2.5, p = .051) and proteoglycan (OR: 5.0, p = .013) histological scores in engineered constructs. Interestingly, engineered constructs outperformed microfracture in clinical scoring, regardless of PEMF treatment (p < .05). Overall, the studies provided evidence that PEMF stimulation enhanced engineered cartilage growth and repair, demonstrating a potential low‐cost, low‐risk, noninvasive treatment modality for expediting early cartilage repair.
Engineered osteochondral constructs were implanted into focal defects created in the stifle (knee) joint. To assess expedited early repair, animals were assessed after a 3‐month recovery period. In vivo, PEMF led to a greater likelihood of normal chondrocyte (odds ratio OR: 2.5, p = .051) and proteoglycan (OR: 5.0, p = .013) histological scores in engineered constructs. Overall, the studies provided evidence that PEMF stimulation enhanced engineered cartilage growth and repair, demonstrating a potential low‐cost, low‐risk, noninvasive treatment modality for expediting early cartilage repair.
Purpose The purpose of this study was to quantify the current trends in knee cartilage surgical techniques performed in the United States from 2004 through 2011 using a large private-payer database. ...A secondary objective was to identify salient demographic factors associated with these procedures. Methods We performed a retrospective database review using a large private-payer medical record database within the PearlDiver database. The PearlDiver database is a publicly available, Health Insurance Portability and Accountability Act–compliant national database compiled from a collection of private insurer records. A search was performed for surgical techniques in cartilage palliation (chondroplasty), repair (microfracture/drilling), and restoration (arthroscopic osteochondral autograft, arthroscopic osteochondral allograft, autologous chondrocyte implantation, open osteochondral allograft, and open osteochondral autograft). The incidence, growth, and demographic factors associated with the surgical procedures were assessed. Results From 2004 through 2011, 198,876,000 patients were analyzed. A surgical procedure addressing a cartilage defect was performed in 1,959,007 patients, for a mean annual incidence of 90 surgeries per 10,000 patients. Across all cartilage procedures, there was a 5.0% annual incidence growth (palliative, 3.7%; repair, 0%; and restorative, 3.1%) ( P = .027). Palliative techniques (chondroplasty) were more common (>2:1 ratio for repair marrow-stimulation techniques and 50:1 ratio for restoration autologous chondrocyte implantation and osteochondral autograft and allograft). Palliative surgical approaches were the most common technique, regardless of age, sex, or region. Conclusions Articular cartilage surgical procedures in the knee are common in the United States, with an annual incidence growth of 5%. Surgical techniques aimed at palliation are more common than cartilage repair and restoration techniques regardless of age, sex, or region. Level of Evidence Level IV, retrospective database analysis.
To investigate the feasibility of cylindrical costal osteochondral graft transplantation as a novel regenerative treatment in growth arrest.
The medial portion of the proximal tibial growth plate of ...6-week-old male New Zealand White rabbits was resected to establish an experimental model of partial growth plate injury. The rabbits were divided into four groups: no-treatment, bone wax transplantation, costal chondral graft, and costal osteochondral graft groups. Radiographic and micro-computed tomography scan results were analyzed to evaluate angular deformity of the tibia and bony bridge formation at the injury site. In addition, repair of the injured growth plate cartilage was assessed histologically at 4, 8, and 12 weeks postoperatively.
Radiographic examination revealed that bone wax transplantation continuously decreased the medial proximal tibial angle (MPTA) while the costal chondral graft implantation reduced the decrease of MPTA at 12 weeks postoperatively. The costal osteochondral graft implantation recovered the MPTA, close to the normal. Histologically, the costal osteochondral grafts retained the MPTA in the injured site compared to costal chondral grafts. Additionally, hypertrophic chondrocytes were observed at the graft site in the costal osteochondral graft group at 12 weeks, suggesting that endochondral ossification may occur at the graft site similar to normal ossification. The fluorescence in situ hybridization analysis of osteochondral grafts transplanted from male to female rabbits indicated that they were replaced by cells of host origin.
The costal osteochondral graft can achieve regeneration without bony bridge formation in partial growth plate injury.
Background:
Recruitment of endogenous stem cells has been considered an alternative to cell injection/implantation in articular cartilage repair.
Purpose:
(1) To develop a cartilage ...tissue-engineering scaffold with clinically available biomaterials and functionalize the scaffold with an aptamer (Apt19s) that specifically recognizes pluripotent stem cells. (2) To determine whether this scaffold could recruit joint-resident mesenchymal stem cells (MSCs) when implanted into an osteochondral defect in a rabbit model and to examine the effects of cartilage regeneration.
Study Design:
Controlled laboratory study.
Methods:
The reinforced scaffold was fabricated by embedding a silk fibroin sponge into silk fibroin/hyaluronic acid–tyramine hydrogel and characterized in vitro. A cylindrical osteochondral defect (3.2 mm wide × 4 mm deep) was created in the trochlear grooves of rabbit knees. The rabbits were randomly assigned into 3 groups: Apt19s-functionalized scaffold group, scaffold-only group, and control group. Animals were sacrificed at 6 and 12 weeks after transplantation. Repaired tissues were evaluated via gross examination, histologic examination, and immunohistochemistry.
Results:
In vitro, this aptamer-functionalized scaffold could recruit bone marrow–derived MSCs and support cell adhesion. In vivo, the aptamer-functionalized scaffold enhanced cell homing in comparison with the aptamer-free scaffold. The aptamer-functionalized scaffold group also exhibited superior cartilage restoration when compared with the scaffold-only group and the control group.
Conclusion:
The Apt19s-functionalized scaffold exhibited the ability to recruit MSCs both in vitro and in vivo and achieved a better outcome of cartilage repair than the scaffold only or control in an osteochondral defect model.
Clinical Relevance:
The findings demonstrate a promising strategy of using aptamer-functionalized bioscaffolds for restoration of chondral/osteochondral defects via aptamer-introduced homing of MSCs.
Osteoarthritis (OA) is a growing public health problem across the globe, affecting more than half of the over 65 population. In the past, OA was considered a wear and tear disease, leading to the ...loss of articular cartilage and joint disability. Nowadays, thanks to advancements in molecular biology, OA is believed to be a very complex multifactorial disease. OA is a degenerative disease characterized by "low-grade inflammation" in cartilage and synovium, resulting in the loss of joint structure and progressive deterioration of cartilage. Although the disease can be dependent on genetic and epigenetic factors, sex, ethnicity, and age (cellular senescence, apoptosis and lubricin), it is also associated with obesity and overweight, dietary factors, sedentary lifestyle and sport injuries. The aim of this review is to highlight how certain behaviors, habits and lifestyles may be involved in the onset and progression of OA and to summarize the principal risk factors involved in the development of this complicated joint disorder.
Background:
Treating articular cartilage defects is a demanding problem. Although several studies have reported durable and improved clinical outcomes after autologous chondrocyte implantation (ACI) ...over a long-term period, there is no report with over 20 years’ follow-up.
Purpose:
To evaluate clinical outcomes after first-generation ACI for the treatment of knees with disabling, large single and multiple cartilage defects for which patients wished to avoid prosthetic arthroplasty, with a minimum of 20 years’ follow-up.
Study Design:
Case series; Level of evidence, 4.
Methods:
The authors reviewed prospectively collected data from 23 patients (24 knees; mean age, 35.4 years range, 13-52 years) undergoing ACI for the treatment of symptomatic, full-thickness articular cartilage lesions. A mean of 2.1 lesions per knee were treated over a mean total surface area of 11.8 cm2 (range, 2.4-30.5 cm2) per knee. Kaplan-Meier survival analysis and functional outcome scores, including the modified Cincinnati Knee Rating System, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Short Form–36 (SF-36), were used. Patients also self-reported an improvement in pain with a visual analog scale and a satisfaction survey.
Results:
The 20-year survival rate was 63% (95% CI, 40%-78%). The evaluation of the 15 knees with retained grafts demonstrated that all clinical scores except the WOMAC subscore for stiffness and SF-36 mental component summary score improved significantly and were sustained to 20 years postoperatively. Ninety-three percent of these patients rated knee-specific outcomes as good or excellent. The outcomes for 9 of 24 knees were considered failures, including 5 undergoing revision ACI and 4 being converted to arthroplasty at a mean of 1.7 and 5.9 years, respectively. Only 1 of 5 knees that underwent revision ACI was converted to arthroplasty at 1.9 years after the index surgery, and the other 4 patients were able to maintain their biological knee. Overall, 20 years later, 79% of patients maintained their native knee, for which they initially sought treatment, and were satisfied when evaluated.
Conclusion:
First-generation ACI provided satisfactory survival rates and significant clinical improvements over a 20-year follow-up, which offers an important standard for comparison with newer-generation ACI technologies of the future.
Summary Objective Mouse articular cartilage (AC) is mostly assessed by histopathology and its mechanics is poorly characterised. In this study: (1) we developed non-destructive imaging for ...quantitative assessment of AC morphology and (2) evaluated the mechanical implications of AC structural changes. Methods Knee joints obtained from naïve mice and from mice with osteoarthritis (OA) induced by destabilization of medial meniscus (DMM) for 4 and 12 weeks, were imaged by phosphotungstic acid (PTA) contrast enhanced micro-computed tomography (PTA-CT) and scored by conventional histopathology. Our software (Matlab) automatically segmented tibial AC, drew two regions centred on each tibial condyle and evaluated the volumes included. A finite element (FE) model of the whole mouse joint was implemented to evaluate AC mechanics. Results Our method achieved rapid, automated analysis of mouse AC (structural parameters in <10 h from knee dissection) and was able to localise AC loss in the central region of the medial tibial condyle. AC thickness decreased by 15% at 4 weeks and 25% at 12 weeks post DMM surgery, whereas histopathology scores were significantly increased only at 12 weeks. FE simulations estimated that AC thinning at early-stages in the DMM model (4 weeks) increases contact pressures (+39%) and Tresca stresses (+43%) in AC. Conclusion PTA-CT imaging is a fast and simple method to assess OA in murine models. Once applied more extensively to confirm its robustness, our approach will be useful for rapidly phenotyping genetically modified mice used for OA research and to improve the current understanding of mouse cartilage mechanics.
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