Effect of a Rapidly Degrading Presolidified 10 kDa Chitosan/Blood Implant and Subchondral Marrow Stimulation Surgical Approach on Cartilage Resurfacing in a Sheep Model

PHB/CHIT Scaffold as a Promising Biopolymer in the Treatment of Osteochondral Defects-An Experimental Animal Study

Biopolymer composites allow the creation of an optimal environment for the regeneration of chondral and osteochondral defects of articular cartilage, where natural regeneration potential is limited. In this experimental study, we used the sheep animal model for the creation of knee cartilage defects. In the medial part of the trochlea and on the medial condyle of the femur, we created artificial defects (6 × 3 mm²) with microfractures. In four experimental sheep, both defects were subsequently filled with the porous acellular polyhydroxybutyrate/chitosan (PHB/CHIT)-based implant. Two sheep had untreated defects. We evaluated the quality of the newly formed tissue in the femoral trochlea defect site using imaging (X-ray, Computer Tomography (CT), Magnetic Resonance Imaging (MRI)), macroscopic, and histological methods. Macroscopically, the surface of the treated regenerate corresponded to the niveau of the surrounding cartilage. X-ray examination 6 months after the implantation confirmed the restoration of the contour in the subchondral calcified layer and the advanced rate of bone tissue integration. The CT scan revealed a low regenerative potential in the bone zone of the defect compared to the cartilage zone. The percentage change in cartilage density at the defect site was not significantly different to the reference area (0.06–6.4%). MRI examination revealed that the healing osteochondral defect was comparable to the intact cartilage signal on the surface of the defect. Hyaline-like cartilage was observed in most of the treated animals, except for one, where the defect was repaired with fibrocartilage. Thus, the acellular, chitosan-based biomaterial is a promising biopolymer composite for the treatment of chondral and osteochondral defects of traumatic character. It has potential for further clinical testing in the orthopedic field, primarily with the combination of supporting factors.

CARGEL Bioscaffold improves cartilage repair tissue after bone marrow stimulation in a minipig model

Purpose

To gain knowledge of the repair tissue in critically sized cartilage defects using bone marrow stimulation combined with CARGEL Bioscaffold (CB) compared with bone marrow stimulation (BMS) alone in a validated animal model.

Methods

Six adult Göttingen minipigs received two chondral defects in each knee. The knees were randomized to either BMS combined with CB or BMS alone. The animals were euthanized after 6 months. Follow-up consisted of histomorphometry, immunohistochemistry, semiquantitative scoring of the repair tissue (ICRS II), and μCT of the trabecular bone beneath the defect.

Results

There was significantly more fibrocartilage (80% vs 64%, p = 0.04) and a trend towards less fibrous tissue (15% vs 30%, p = 0.05) in the defects treated with CB. Hyaline cartilage was only seen in one defect treated with CB and none treated with BMS alone.

For histological semiquantitative score (ICRS II), defects treated with CB scored lower on subchondral bone (69 vs. 44, p = 0.04). No significant differences were seen on the other parameters of the ICRS II. Immunohistochemistry revealed a trend towards more positive staining for collagen type II in the CB group (p = 0.08). μCT demonstrated thicker trabeculae (p = 0.029) and a higher bone material density (p = 0.028) in defects treated with CB.

Conclusion

Treatment of cartilage injuries with CARGEL Bioscaffold seems to lead to an improved repair tissue and a more pronounced subchondral bone response compared with bone marrow stimulation alone. However, the CARGEL Bioscaffold treatment did not lead to formation of hyaline cartilage.

A cell-free approach with a supporting biomaterial in the form of dispersed microspheres induces hyaline cartilage formation in a rabbit knee model

The objective of this study was to test a regenerative medicine strategy for the regeneration of articular cartilage. This approach combines microfracture of the subchondral bone with the implant at the site of the cartilage defect of a supporting biomaterial in the form of microspheres aimed at creating an adequate biomechanical environment for the differentiation of the mesenchymal stem cells that migrate from the bone marrow. The possible inflammatory response to these biomaterials was previously studied by means of the culture of RAW264.7 macrophages. The microspheres were implanted in a 3 mm-diameter defect in the trochlea of the femoral condyle of New Zealand rabbits, covering them with a poly(l-lactic acid) (PLLA) membrane manufactured by electrospinning. Experimental groups included a group where exclusively PLLA microspheres were implanted, another group where a mixture of 50/50 microspheres of PLLA (hydrophobic and rigid) and others of chitosan (a hydrogel) were used, and a third group used as a control where no material was used and only the membrane was covering the defect. The histological characteristics of the regenerated tissue have been evaluated 3 months after the operation. We found that during the regeneration process the microspheres, and the membrane covering them, are displaced by the neoformed tissue in the regeneration space toward the subchondral bone region, leaving room for the formation of a tissue with the characteristics of hyaline cartilage.

Articular cartilage regeneration and tissue engineering models: a systematic review

INTRODUCTION

Cartilage regeneration and restoration is a major topic in orthopedic research as cartilaginous degeneration and damage is associated with osteoarthritis and joint destruction. This systematic review aims to summarize current research strategies in cartilage regeneration research.

MATERIALS AND METHODS

A Pubmed search for models investigating single-site cartilage defects as well as chondrogenesis was conducted and articles were evaluated for content by title and abstract. Finally, only manuscripts were included, which report new models or approaches of cartilage regeneration.

RESULTS

The search resulted in 2217 studies, 200 of which were eligible for inclusion in this review. The identified manuscripts consisted of a large spectrum of research approaches spanning from cell culture to tissue engineering and transplantation as well as sophisticated computational modeling.

CONCLUSIONS

In the past three decades, knowledge about articular cartilage and its defects has multiplied in clinical and experimental settings and the respective body of research literature has grown significantly. However, current strategies for articular cartilage repair have not yet succeeded to replicate the structure and function of innate articular cartilage, which makes it even more important to understand the current strategies and their impact. Therefore, the purpose of this review was to globally summarize experimental strategies investigating cartilage regeneration in vitro as well as in vivo. This will allow for better referencing when designing new models or strategies and potentially improve research translation from bench to bedside.