Macroscopic cartilage repair scoring of defect fill, integration and total points correlate with corresponding items in histological scoring systems - a study in adult sheep

Locally Directed Recombinant Adeno- Associated Virus-Mediated IGF-1 Gene Therapy Enhances Osteochondral Repair and Counteracts Early Osteoarthritis In Vivo

BACKGROUND

Restoration of osteochondral defects is critical, because osteoarthritis (OA) can arise.

HYPOTHESIS

Overexpression of insulin-like growth factor 1 (IGF-1) via recombinant adeno-associated viral (rAAV) vectors (rAAV-IGF-1) would improve osteochondral repair and reduce parameters of early perifocal OA in sheep after 6 months in vivo.

STUDY DESIGN

Controlled laboratory study.

METHODS

Osteochondral defects were created in the femoral trochlea of adult sheep and treated with rAAV-IGF-1 or rAAV-lacZ (control) (24 defects in 6 knees per group). After 6 months in vivo, osteochondral repair and perifocal OA were assessed by well-established macroscopic, histological, and immunohistochemical scoring systems as well as biochemical and micro-computed tomography evaluations.

RESULTS

Application of rAAV-IGF-1 led to prolonged (6 months) IGF-1 overexpression without adverse effects, maintaining a significantly superior overall cartilage repair, together with significantly improved defect filling, extracellular matrix staining, cellular morphology, and surface architecture compared with rAAV-lacZ. Expression of type II collagen significantly increased and that of type I collagen significantly decreased. Subchondral bone repair and tidemark formation were significantly improved, and subchondral bone plate thickness and subarticular spongiosa mineral density returned to normal. The OA parameters of perifocal structure, cell cloning, and matrix staining were significantly better preserved upon rAAV-IGF-1 compared with rAAV-lacZ. Novel mechanistic associations between parameters of osteochondral repair and OA were identified.

CONCLUSION

Local rAAV-mediated IGF-1 overexpression enhanced osteochondral repair and ameliorated parameters of perifocal early OA.

CLINICAL RELEVANCE

IGF-1 gene therapy may be beneficial in repair of focal osteochondral defects and prevention of perifocal OA.

Regeneration of injured articular cartilage using the recombinant human amelogenin protein

Aims

Cartilage injuries rarely heal spontaneously and often require surgical intervention, leading to the formation of biomechanically inferior fibrous tissue. This study aimed to evaluate the possible effect of amelogenin on the healing process of a large osteochondral injury (OCI) in a rat model.

Methods

A reproducible large OCI was created in the right leg femoral trochlea of 93 rats. The OCIs were treated with 0.1, 0.5, 1.0, 2.5, or 5.0 μg/μl recombinant human amelogenin protein (rHAM+) dissolved in propylene glycol alginate (PGA) carrier, or with PGA carrier alone. The degree of healing was evaluated 12 weeks after treatment by morphometric analysis and histological evaluation. Cell recruitment to the site of injury as well as the origin of the migrating cells were assessed four days after treatment with 0.5 μg/μl rHAM+ using immunohistochemistry and immunofluorescence.

Results

A total of 12 weeks after treatment, 0.5 μg/μl rHAM+ brought about significant repair of the subchondral bone and cartilage. Increased expression of proteoglycan and type II collagen and decreased expression of type I collagen were revealed at the surface of the defect, and an elevated level of type X collagen at the newly developed tide mark region. Conversely, the control group showed osteoarthritic alterations. Recruitment of cells expressing the mesenchymal stem cell (MSC) markers CD105 and STRO-1, from adjacent bone marrow toward the OCI, was noted four days after treatment.

Conclusion

We found that 0.5 μg/μl rHAM+ induced in vivo healing of injured articular cartilage and subchondral bone in a rat model, preventing the destructive post-traumatic osteoarthritic changes seen in control OCIs, through paracrine recruitment of cells a few days after treatment.

Multileveled Hierarchical Hydrogel with Continuous Biophysical and Biochemical Gradients for Enhanced Repair of Full-Thickness Osteochondral Defect

The repair of hierarchical osteochondral defect requires sophisticated gradient reestablishment; however, few strategies for continuous gradient casting consider the relevance to clinical practice regarding cell adaptability, multiple gradient elements, and precise gradient mirroring native tissue. Here, a hydrogel with continuous gradients in nano-hydroxyapatite (HA) content, mechanical, and magnetism is developed using synthesized superparamagnetic HA nanorods (MagHA) that easily respond to a brief magnetic field. To precisely reconstruct osteochondral tissue, the optimized gradient mode is calculated according to magnetic resonance imaging (MRI) of healthy rabbit knees. Then, MagHA are patterned to form continuous biophysical and biochemical gradients, consequently generating incremental HA, mechanical, and electromagnetic cues under an external magnetic stimulus. To make such depth-dependent biocues work, an adaptable hydrogel is developed to facilitate cell infiltration. Furthermore, this approach is applied in rabbit full-thickness osteochondral defects equipped with a local magnetic field. Surprisingly, this multileveled gradient composite hydrogel repairs osteochondral unit in a perfect heterogeneous feature, which mimics the gradual cartilage-to-subchondral transition. Collectively, this is the first study that combines an adaptable hydrogel with magneto-driven MagHA gradients to achieve promising outcomes in osteochondral regeneration.

Arthroscopic International Cartilage Repair Society Classification System Has Only Moderate Reliability in a Porcine Cartilage Repair Model

BACKGROUND

The International Cartilage Repair Society (ICRS) score was designed for arthroscopic use to evaluate the quality of cartilage repair.

PURPOSE

To evaluate the reliability of the ICRS scoring system using an animal cartilage repair model.

STUDY DESIGN

Controlled laboratory study.

METHODS

A chondral defect with an area of 1.5 cm² was made in the medial femoral condyle of 18 domestic pigs. Five weeks later, 9 pigs were treated using a novel recombinant human type III collagen/polylactide scaffold, and 9 were left to heal spontaneously. After 4 months, the pigs were sacrificed, then 3 arthroscopic surgeons evaluated the medial femoral condyles via video-recorded simulated arthroscopy using the ICRS scoring system. The surgeons repeated the evaluation twice within a 9-month period using their recorded arthroscopy.

RESULTS

The porcine cartilage repair model produced cartilage repair tissue of poor to good quality. The mean ICRS total scores for all observations were 6.6 (SD, 2.6) in arthroscopy, 5.9 (SD, 2.7) in the first reevaluation, and 6.2 (SD, 2.8) in the second reevaluation. The interrater reliability with the intraclass correlation coefficient (ICC) for the ICRS total scores (ICC, 0.46-0.60) and for each individual subscore (ICC, 0.26-0.71) showed poor to moderate reliability. The intrarater reliability with the ICC also showed poor to moderate reliability for ICRS total scores (ICC, 0.52-0.59) and for each individual subscore (ICC, 0.29-0.58). A modified Bland-Altman plot for the initial arthroscopy and for the 2 reevaluations showed an evident disagreement among the observers.

CONCLUSION

In an animal cartilage repair model, the ICRS scoring system seems to have poor to moderate reliability.

CLINICAL RELEVANCE

Arthroscopic assessment of cartilage repair using the ICRS scoring method has limited reliability. We need more objective methods with acceptable reliability to evaluate cartilage repair outcomes.

Hydrogel-Guided, rAAV-Mediated IGF-I Overexpression Enables Long-Term Cartilage Repair and Protection against Perifocal Osteoarthritis in a Large-Animal Full-Thickness Chondral Defect Model at One Year In Vivo

The regeneration of focal articular cartilage defects is complicated by the reduced quality of the repair tissue and the potential development of perifocal osteoarthritis (OA). Biomaterial-guided gene therapy may enhance cartilage repair by controlling the release of therapeutic sequences in a spatiotemporal manner. Here, the benefits of delivering a recombinant adeno-associated virus (rAAV) vector coding for the human insulin-like growth factor I (IGF-I) via an alginate hydrogel (IGF-I/AlgPH155) to enhance repair of full-thickness chondral defects following microfracture surgery after one year in minipigs versus control (lacZ/AlgPH155) treatment are reported. Sustained IGF-I overexpression is significantly achieved in the repair tissue of defects treated with IGF-I/AlgPH155 versus those receiving lacZ/AlgPH155 for one year and in the cartilage surrounding the defects. Administration of IGF-I/AlgPH155 significantly improves parameters of cartilage repair at one year relative to lacZ/AlgPH155 (semiquantitative total histological score, cell densities, matrix deposition) without deleterious or immune reactions. Remarkably, delivery of IGF-I/AlgPH155 also significantly reduces perifocal OA and inflammation after one year versus lacZ/AlgPH155 treatment. Biomaterial-guided rAAV gene transfer represents a valuable clinical approach to promote cartilage repair and to protect against OA.

Repair of full-thickness articular cartilage defects using IEIK13 self-assembling peptide hydrogel in a non-human primate model

Articular cartilage is built by chondrocytes which become less active with age. This declining function of the chondrocytes, together with the avascular nature of the cartilage, impedes the spontaneous healing of chondral injuries. These lesions can progress to more serious degenerative articular conditions as in the case of osteoarthritis. As no efficient cure for cartilage lesions exist yet, cartilage tissue engineering has emerged as a promising method aiming at repairing joint defects and restoring articular function. In the present work, we investigated if a new self-assembling peptide (referred as IEIK13), combined with articular chondrocytes treated with a chondrogenic cocktail (BMP-2, insulin and T3, designated BIT) could be efficient to restore full-thickness cartilage defects induced in the femoral condyles of a non-human primate model, the cynomolgus monkey. First, in vitro molecular studies indicated that IEIK13 was efficient to support production of cartilage by monkey articular chondrocytes treated with BIT. In vivo, cartilage implant integration was monitored non-invasively by contrast-enhanced micro-computed tomography, and then by post-mortem histological analysis and immunohistochemical staining of the condyles collected 3 months post-implantation. Our results revealed that the full-thickness cartilage injuries treated with either IEIK13 implants loaded with or devoid of chondrocytes showed similar cartilage-characteristic regeneration. This pilot study demonstrates that IEIK13 can be used as a valuable scaffold to support the in vitro activity of articular chondrocytes and the repair of articular cartilage defects, when implanted alone or with chondrocytes.

Comparative anatomy and morphology of the knee in translational models for articular cartilage disorders. Part I: Large animals

BACKGROUND

The human knee is a complex joint, and affected by a variety of articular cartilage disorders. Large animal models are critical to model the complex disease mechanisms affecting a functional joint. Species-dependent differences highly affect the results of a pre-clinical study and need to be considered, necessitating specific knowledge not only of macroscopic and microscopic anatomical and pathological aspects, but also characteristics of their individual gait and joint movements.

METHODS

Literature search in Pubmed.

RESULTS AND DISCUSSION

This narrative review summarizes the most relevant anatomical structural and functional characteristics of the knee (stifle) joints of the major translational large animal species, comprising dogs, (mini)pigs, sheep, goats, and horses in comparison with humans. Specific characteristics of each species, including kinematical gait parameters are provided. Considering these multifactorial dimensions will allow to select the appropriate model for answering the research questions in a clinically relevant fashion.

Long-term hydrolytic degradation study of polycaprolactone films and fibers grafted with poly(sodium styrene sulfonate): Mechanism study and cell response

Polycaprolactone (PCL) is a widely used biodegradable polyester for tissue engineering applications when long-term degradation is preferred. In this article, we focused on the analysis of the hydrolytic degradation of virgin and bioactive poly(sodium styrene sulfonate) (pNaSS) functionalized PCL surfaces under simulated physiological conditions (phosphate buffer saline at 25 and 37 °C) for up to 120 weeks with the aim of applying bioactive PCL for ligament tissue engineering. Techniques used to characterize the bulk and surface degradation indicated that PCL was hydrolyzed by a bulk degradation mode with an accelerated degradation-three times increased rate constant-for pNaSS grafted PCL at 37 °C when compared to virgin PCL at 25 °C. The observed degradation mechanism is due to the pNaSS grafting process (oxidation and radical polymerization), which accelerated the degradation until 48 weeks, when a steady state is reached. The PCL surface was altered by pNaSS grafting, introducing hydrophilic sulfonate groups that increase the swelling and smoothing of the surface, which facilitated the degradation. After 48 weeks, pNaSS was largely removed from the surface, and the degradation of virgin and pNaSS grafted surfaces was similar. The cell response of primary fibroblast cells from sheep ligament was consistent with the surface analysis results: a better initial spreading of cells on pNaSS surfaces when compared to virgin surfaces and a tendency to become similar with degradation time. It is worthy to note that during the extended degradation process the surfaces were able to continue inducing better cell spreading and preserve their cell phenotype as shown by collagen gene expressions.

The Treatment of Cartilage Damage Using Human Mesenchymal Stem Cell-Derived Extracellular Vesicles: A Systematic Review of in vivo Studies

Damage to joints through injury or disease can result in cartilage loss, which if left untreated can lead to inflammation and ultimately osteoarthritis. There is currently no cure for osteoarthritis and management focusses on symptom control. End-stage osteoarthritis can be debilitating and ultimately requires joint replacement in order to maintain function. Therefore, there is growing interest in innovative therapies for cartilage repair. In this systematic literature review, we sought to explore the in vivo evidence for the use of human Mesenchymal Stem Cell-derived Extracellular Vesicles (MSC-EVs) for treating cartilage damage. We conducted a systematic literature review in accordance with the PRISMA protocol on the evidence for the treatment of cartilage damage using human MSC-EVs. Studies examining in vivo models of cartilage damage were included. A risk of bias analysis of the studies was conducted using the SYRCLE tool. Ten case-control studies were identified in our review, including a total of 159 murine subjects. MSC-EVs were harvested from a variety of human tissues. Five studies induced osteoarthritis, including cartilage loss through surgical joint destabilization, two studies directly created osteochondral lesions and three studies used collagenase to cause cartilage loss. All studies in this review reported reduced cartilage loss following treatment with MSC-EVs, and without significant complications. We conclude that transplantation of MSC-derived EVs into damaged cartilage can effectively reduce cartilage loss in murine models of cartilage injury. Additional randomized studies in animal models that recapitulates human osteoarthritis will be necessary in order to establish findings that inform clinical safety in humans.

Assessment of Cartilage Repair Quality With the International Cartilage Repair Society Score and the Oswestry Arthroscopy Score

The International Cartilage Repair Society (ICRS) score and the Oswestry Arthroscopic Score (OAS) have been validated to evaluate repair tissue quality. However, the performance of these scores has not been studied in typical patients undergoing cartilage repair and who have lesions of varying sizes. In this study, we compared the performance of the ICRS and the OAS scores and analyzed the effect of lesion characteristics on the performance of these two scores. Cartilage repair quality was assessed in a total of 104 arthroscopic observations of cartilage repair sites of the knee in 62 patients after autologous chondrocyte implantation. Two observers scored the repair areas independently with the ICRS and the OAS scores. The performance of both scores was evaluated according to internal consistency and inter-rater reliability and correlation between the scores. The frequency and proportion of disagreements were analyzed according to the repair site area and the given score. The correlation between the scores was good (r = 0.91, 95% confidence interval [CI]: 0.87-0.94). Both scores showed moderate internal consistency and inter-rater reliability. Cronbach's α was 0.88 (95% CI: 0.80-0.92) for the ICRS score and 0.79 (95% CI: 0.70-0.86) for the OAS score. The intraclass correlation coefficient was 0.89 (95% CI: 0.84-0.92) for the ICRS and 0.81 (95% CI: 0.74-0.87) for the OAS scores. The frequency and proportion of disagreements were higher in larger repair sites. In arthroscopic use, both ICRS and OAS scores perform similarly, however, their reliability deteriorates as the lesion size increases. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 38:555-562, 2020.

Analysis of early cellular responses of anterior cruciate ligament fibroblasts seeded on different molecular weight polycaprolactone films functionalized by a bioactive poly(sodium styrene sulfonate) polymer

With the growing number of anterior cruciate ligament (ACL) ruptures and the increased interest for regenerative medicine procedures, many studies are now concentrated on developing bioactive and biodegradable synthetic ligaments. For this application, the choice of raw materials with appropriate physicochemical characteristics and long-term degradation features is essential. Polycaprolactone (PCL) has the advantage of slow degradation that depends on its molecular weight. This study evaluates two PCL materials: a technical grade (PC60: 60 kDa) versus a medical grade (PC12: 80 kDa), both before and after functionalization with poly(sodium styrene sulfonate) (pNaSS). After determining the grafting process had little to no effect on the PCL physicochemical properties, sheep ACL fibroblast responses were investigated. The PC12 films induced a significantly lower expression of the tumor necrosis factor alpha inflammatory gene compared to the PC60 films. Both film types induced an overproduction of fibroblast growth factor-2 and transforming growth factor beta compared to the controls on day 5 and demonstrated collagen gene expression profiles similar to the controls on day 7. Upon protein adsorption, pNaSS grafting caused a rapid cell adhesion in the first 30 min and an increased adhesion strength (1.5-fold higher). Moreover, after 7 days, an increase in cell density and actin network development were noted on the grafted films.

Photopolymerizable Injectable Cartilage Mimetic Hydrogel for the Treatment of Focal Chondral Lesions: A Proof of Concept Study in a Rabbit Animal Model

BACKGROUND

In this study, we investigate the in vitro and in vivo chondrogenic capacity of a novel photopolymerizable cartilage mimetic hydrogel, enhanced with extracellular matrix analogs, for cartilage regeneration.

PURPOSE

To (1) determine whether mesenchymal stem cells (MSCs) embedded in a novel cartilage mimetic hydrogel support in vitro chondrogenesis, (2) demonstrate that the proposed hydrogel can be delivered in situ in a critical chondral defect in a rabbit model, and (3) determine whether the hydrogel with or without MSCs supports in vivo chondrogenesis in a critical chondral defect.

STUDY DESIGN

Controlled laboratory study.

METHODS

Rabbit bone marrow-derived MSCs were isolated, expanded, encapsulated in the hydrogel, and cultured in chondrogenic differentiation medium for 9 weeks. Compressive modulus was evaluated at day 1 and at weeks 3, 6, and 9. Chondrogenic differentiation was investigated via quantitative polymerase reaction, safranin-O staining, and immunofluorescence. In vivo, a 3 mm-wide × 2-mm-deep chondral defect was created bilaterally on the knee trochlea of 10 rabbits. Each animal had 1 defect randomly assigned to be treated with hydrogel with or without MSCs, and the contralateral knee was left untreated. Hence, each rabbit served as its own matched control. Three groups were established: group A, hydrogel (n = 5); group B, hydrogel with MSCs (n = 5); and group C, control (n = 10). Repair tissue was evaluated at 6 months after intervention.

RESULTS

In vitro, chondrogenesis and the degradable behavior of the hydrogel by MSCs were confirmed. In vivo, the hydrogel could be delivered intraoperatively in a sterile manner. Overall, the hydrogel group had the highest scores on the modified O'Driscoll scoring system (group A, 17.4 ± 4.7; group B, 13 ± 3; group C, 16.7 ± 2.9) ( P = .11) and showed higher safranin-O staining (group A, 49.4% ± 20%; group B, 25.8% ± 16.4%; group C, 36.9% ± 25.2%) ( P = .27), although significance was not detected for either parameter.

CONCLUSION

This study provides the first evidence of the ability to photopolymerize this novel hydrogel in situ and assess its ability to provide chondrogenic cues for cartilage repair in a small animal model. In vitro chondrogenesis was evident when MSCs were encapsulated in the hydrogel.

CLINICAL RELEVANCE

Cartilage mimetic hydrogel may offer a tissue engineering approach for the treatment of osteochondral lesions.