Histopathology atlas of animal model systems – overview of guiding principles

Abstract

Animal model systems represent an important adjunct and surrogate for studies of osteoarthritis (OA) in humans. They provide a means to study OA pathophysiology as well as aid in the development of therapeutic agents and biological markers for diagnosing and prognosing the disease. Thus, it is of great importance for the OA scientific community, both in academic as well as industrial research, to standardize scoring systems for evaluating the OA disease process and to make results between different studies comparable. The task of the histopathology initiative of OARSI was to achieve a consensus of scoring systems for the most important species used in OA animal model research (dog, guinea pig, horse, mouse, rabbit, rat, and sheep/goat), which are presented in the various chapters in this special volume of Osteoarthritis & Cartilage together with extra chapters on basic methodology (histochemistry, statistics, morphometry), the specific terminology and a general discussion of animal models in OA research. Standardized definitions are suggested for basic but essential terms such as "grading" and "staging" in order to promote their consistent use and thereby promote improved understanding and data interpretation across all model systems. Thus, this introductory chapter presents an overview of the guiding principles for assessment of important OA animal model systems. Use of such systems, independently or in conjunction with other systems in parallel, should facilitate comparability of results across animal model studies.

Benefits of Recombinant Adeno-Associated Virus (rAAV)-Mediated Insulinlike Growth Factor I (IGF-I) Overexpression for the Long-Term Reconstruction of Human Osteoarthritic Cartilage by Modulation of the IGF-I Axis

“…Additional future studies will be required to test the effects of the construct in vivo, taking care of selecting an experimental model of OA that is the most adequate to reproduce the clinical situation among the many systems available to date (8,12,21,84) and of first reproducing the current findings using human cells by translation to such animal cells. The present findings provide motivation to further elaborate the current approach for human OA.…”

Osteoarthritis in horses - Part 2: a review of the intra-articular use of corticosteroids as a method of treatment

“…Studies have shown that it is possible to intervene early in post-traumatic OA, but according to McIIwraith et al (2012b), it is still difficult to determine and identify the most appropriate time to take those steps. Animal models are considered an important complementary and substitutive option for humans in the investigation of OA pathogenesis because animal studies offer information about the pathophysiology of the disorder, allowing the development of drugs and biological markers that contribute to the diagnosis and prognosis (Aigner et al 2010). Research with horses, considered an excellent trial model for musculoskeletal diseases (van Schie et al 2000;Chiaradia et al 2012), may be of value in determining the ideal treatment, considering the frequency of OA in the species (McIIwraith 2005;Goodrich and Nixon 2006) and the availability of well-defined experimental models of OA induction.…”

“…The use of some species allows the study of early pathophysiological events, which is essential for determining treatment and for the research of new therapies (McIIwraith et al 2012b). Because the horse is involved in occupational and sport activities, it is considered a good animal model for human articular diseases (Aigner et al 2010). According to Chiaradia et al (2012), data obtained from this species can "provide suggestive information for tentative biomedical extrapolations", thereby overcoming the limitations on the size of the joint and "workload that are typical of other small animal models".…”

Animal Model of Osteoarthritis

“…Non-calcified cartilage loss tends to be an all-or-none phenomenon, with the pathology of cartilage degeneration rapidly progressing to full-depth fibrillation. Adult rabbit articular cartilage has a cell density ten-fold of that in adult humans (38). Because OA is considered an organ failure, histologic analysis encompassing not only cartilage but also all of joint structure should be performed.…”