A Pathophysiological Validation of Collagenase II-Induced Biochemical Osteoarthritis Animal Model in Rabbit

Animal Models of Osteoarthritis: Updated Models and Outcome Measures 2016-2023

Purpose

Osteoarthritis (OA) is a global musculoskeletal disorder that affects primarily the knee and hip joints without any FDA-approved disease-modifying therapies. Animal models are essential research tools in developing therapies for OA; many animal studies have provided data for the initiation of human clinical trials. Despite this, there is still a need for strategies to recapitulate the human experience using animal models to better develop treatments and understand pathogenesis. Since our last review on animal models of osteoarthritis in 2016, there have been exciting updates in OA research and models. The main purpose of this review is to update the latest animal models and key features of studies in OA research.

Method

We used our existing classification method and screened articles in PubMed and bibliographic search for animal OA models between 2016 and 2023. Relevant and high-cited articles were chosen for inclusion in this narrative review.

Results

Recent studies were analyzed and classified. We also identified ex vivo models as an area of ongoing research. Each animal model offers its own benefit in the study of OA and there are a full range of outcome measures that can be assessed. Despite the vast number of models, each has its drawbacks that have limited translating approved therapies for human use.

Conclusion

Depending on the outcome measures and objective of the study, researchers should pick the best model for their work. There have been several exciting studies since 2016 that have taken advantage of regenerative engineering techniques to develop therapies and better understand OA.

Lay Summary

Osteoarthritis (OA) is a chronic debilitating disease without any cure that affects mostly the knee and hip joints and often results in surgical joint replacement. Cartilage protects the joint from mechanical forces and degrades with age or in response to injury. The many contributing causes of OA are still being investigated, and animals are used for preclinical research and to test potential new treatments. A single consensus OA animal model for preclinical studies is non-existent. In this article, we review the many animal models for OA and provide a much-needed update on studies and model development since 2016.

Knee osteoarthritis: A review of animal models and intervention of traditional Chinese medicine

BACKGROUND

Knee osteoarthritis (KOA) characterized by degeneration of knee cartilage and subsequent bone hyperplasia is a prevalent joint condition primarily affecting aging adults. The pathophysiology of KOA remains poorly understood, as it involves complex mechanisms that result in the same outcome. Consequently, researchers are interested in studying KOA and require appropriate animal models for basic research. Chinese herbal compounds, which consist of multiple herbs with diverse pharmacological properties, possess characteristics such as multicomponent, multipathway, and multitarget effects. The potential benefits in the treatment of KOA continue to attract attention.

PURPOSE

This study aims to provide a comprehensive overview of the advantages, limitations, and specific considerations in selecting different species and methods for KOA animal models. This will help researchers make informed decisions when choosing an animal model.

METHODS

Online academic databases (e.g., PubMed, Google Scholar, Web of Science, and CNKI) were searched using the search terms "knee osteoarthritis," "animal models," "traditional Chinese medicine," and their combinations, primarily including KOA studies published from 2010 to 2023.

RESULTS

Based on literature retrieval, this review provides a comprehensive overview of the methods of establishing KOA animal models; introduces the current status of advantages and disadvantages of various animal models, including mice, rats, rabbits, dogs, and sheep/goats; and presents the current status of methods used to establish KOA animal models.

CONCLUSION

This study provides a review of the animal models used in recent KOA research, discusses the common modeling methods, and emphasizes the role of traditional Chinese medicine compounds in the treatment of KOA.

Contrast-enhanced x-ray microscopy of articular cartilage

Osteoarthritis is a common chronic disease of joints characterized by degenerative changes of articular cartilage. An early diagnosis of osteoarthritis may be possible when imaging excised tissue for research in situ at the cellular-molecular scale. Whereas cartilage histopathology is destructive, time-consuming, and limited to 2D views, contrast-enhanced x-ray microscopy (XRM) can image articular cartilage and subchondral bone in 3D. This study evaluates articular cartilage structure ex vivo using both techniques.Osteochondral plugs were excised from non-diseased bovine knees and stained in phosphotungstic acid for 0 to 32 h. XRM imaging revealed an optimal staining time of 16 h and a saturated staining time of 24 h. Histology sections were cut and analyzed by polarized light microscopy (PLM) and second-harmonic-generation dual-photon (SHG-DP) microscopy. Histology photomicrographs were aligned with matching XRM slices and evaluated for features relevant in histopathological scoring of osteoarthritis cartilage, including the tidemark, collagen architecture and chondrocyte morphology.The cartilage collagen network and chondrocytes from the 3D contrast-enhanced XRM were correlated with the 2D histology. This technique has two distinct advantages over routine histopathology: (1) the avoidance of dehydration, demineralization, and deformation of histological sectioning, thereby preserving the intact articular cartilage and subchondral bone plate ex vivo, and (2) the ability to evaluate the entire osteochondral volume in 3D. This work explores several diagnostic features of imaging cartilage, including: visualization of the tidemark in XRM and SHG-DP microscopy, validating the morphology of chondrocytes and nuclei with XRM, SHG-DP and PLM, and correlating collagen birefringence with XRM image intensity.

Regenerative Engineering Animal Models for Knee Osteoarthritis

Abstract

Osteoarthritis (OA) of the knee is the most common synovial joint disorder worldwide, with a growing incidence due to increasing rates of obesity and an aging population. A significant amount of research is currently being conducted to further our understanding of the pathophysiology of knee osteoarthritis to design less invasive and more effective treatment options once conservative management has failed. Regenerative engineering techniques have shown promising preclinical results in treating OA due to their innovative approaches and have emerged as a popular area of study. To investigate these therapeutics, animal models of OA have been used in preclinical trials. There are various mechanisms by which OA can be induced in the knee/stifle of animals that are classified by the etiology of the OA that they are designed to recapitulate. Thus, it is essential to utilize the correct animal model in studies that are investigating regenerative engineering techniques for proper translation of efficacy into clinical trials. This review discusses the various animal models of OA that may be used in preclinical regenerative engineering trials and the corresponding classification system.

Lay Summary

Osteoarthritis (OA) of the knee is the most common synovial joint disease worldwide, with high rates of occurrence due to an increase in obesity and an aging population. A great deal of research is currently underway to further our understanding of the causes of osteoarthritis, to design more effective treatments. The emergence of regenerative engineering has provided physicians and investigators with unique opportunities to join ideas in tackling human diseases such as OA. Once the concept is proven to work, the initial procedure for the evaluation of a treatment solution begins with an animal model. Thus, it is essential to utilize a suitable animal model that reflects the particular ailment in regenerative engineering studies for proper translation to human patients as each model has associated advantages and disadvantages. There are various ways by which OA can occur in the knee joint, which are classified according to the particular cause of the OA. This review discusses the various animal models of OA that may be used in preclinical regenerative engineering investigations and the corresponding classification system.

A novel method to establish the rabbit model of knee osteoarthritis: intra-articular injection of SDF-1 induces OA

Background

Animal model of Knee Osteoarthritis (OA) is the primary testing methodology for studies on pathogenic mechanisms and therapies of human OA disease. Recent major modeling methods are divided into artificially induced and spontaneous. However, these methods have some disadvantages of slow progression, high cost and no correlation with the pathogenesis of OA.

Methods

Our studies attempted to find a rapid, easy, and consistent with the natural pathological process of OA modeling method by intra-articular injection of stromal cell-derived factor 1 (SDF-1) in the rabbit knee. After induction we collected cartilage specimens from the medial femoral condyle to undergo macroscopic, histological, immunohistochemical, and biochemical evaluations. Meanwhile, compared with Hulth surgical method to evaluate its efficacy.

Results

Macroscopic observation and modified Mankin score of histological staining exhibited typical features of middle stage OA cartilage in SDF-1 injected groups. Immunohistochemically, the positive expression of interleukin-1 (IL-1) and tumor necrosis factor α(TNF-α) was earlier and higher in high dose SDF-1 group than the surgical group. The matrix metalloproteinases (MMPs) in synovial fluid and chondrocytes significantly increased, but type II collagen (COLII) and aggrecan (ACAN) protein expressions decreased in SDF-1 injected group following the extension of time and increase of SDF-1 concentration.

Conclusions

Our data indicated intra-articular injection of SDF-1 (40μg/kg, three times for 12 weeks) can induce rabbit knee OA model successfully more rapidly and easily than traditional surgical modeling. The study provided a further option for the establishment of knee OA animal model.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04188-7.

Hypoxia/reoxygenation activates the JNK pathway and accelerates synovial senescence

Hypoxia/reoxygenation (H/R) may play an important role via senescence in the mechanism of osteoarthritis (OA) development. The synovial membrane is highly sensitive to H/R due to its oxygen consumption feature. Excessive mechanical loads and oxidative stress caused by H/R induce a senescence-associated secretory phenotype (SASP), which is related to the development of OA. The aim of the present study was to investigate the differences of SASP manifestation in synovial tissue masses between tissues from healthy controls and patients with OA. The present study used tumor necrosis factor-α (TNF-α) to pre-treat synovial tissue and fibroblast-like synoviocytes (FLS) to observe the effect of inflammatory cytokines on the synovial membrane before H/R. It was determined that H/R increased interleukin (IL)-1β and IL-6 expression levels in TNF-α-induced cell culture supernatants, increased the proportion of SA-β-gal staining, and increased the expression levels of high mobility group box 1, caspase-8, p16, p21, matrix metalloproteinase (MMP)-3 and MMP-13 in the synovium. Furthermore, H/R opened the mitochondrial permeability transition pore, caused the loss of mitochondrial membrane potential (ΔΨm) and increased the release of reactive oxygen species (ROS). Moreover, H/R caused the expansion of the mitochondrial matrix and rupture of the mitochondrial extracorporeal membrane, with a decrease in the number of cristae. In addition, H/R induced activation of the JNK signaling pathway in FLS to induce cell senescence. Thus, the present results indicated that H/R may cause inflammation and escalate synovial inflammation induced by TNF-α, which may lead to the pathogenesis of OA by increasing changes in synovial SASP and activating the JNK signaling pathway. Therefore, further studies expanding on the understanding of the pathogenesis of H/R etiology in OA are required.

Comparison of early-stage changes of osteoarthritis in cartilage and subchondral bone between two different rat models

Osteoarthritis (OA) is a chronic degenerative joint disease and the major cause of joint pain and disability in the elderly. It is mainly characterized by articular cartilage degradation and subchondral bone remodeling. There are two main types of OA: natural occurring OA and secondary OA, mainly associated with aging and trauma, respectively. In this study, we established two OA models in rat knee joints to simulate the two types of OA, using the type II collagenase injection (CI) and anterior cruciate ligament transection (ACLT), respectively. After intervention for 2-6 weeks, cartilage and subchondral bone changes were detected in histological staining, immunochemistry, and micro-CT. Results showed that both models with typical pathology changes of OA were successfully induced, while the development and severity of OA process in the models were different. In ACLT rats, the cartilage damage was milder, lasted for a shorter time, and subchondral bone reconstruction occurred earlier, compared with the changes in CI rats. The cartilage damage was secondary to subchondral bone change in ACLT rats, while subchondral bone change was secondary to cartilage degeneration in CI rats. In conclusion, the interaction between cartilage and subchondral bone is different between the natural-occurring and secondary OA models. These two models not only suggest potential different mechanisms of the two types of OA, but also provide new directions for OA treatment and prevention.