Colony housing promotes structural and functional changes during surgically induced osteoarthritis in rats.

Objective: The aim of the study was to investigate how social housing with high locomotion activity affects experimental osteoarthritis (OA) in rats. Design: Rats were housed either conventionally in type IV cages in pairs or in rat colony cages (RCC) on 4 levels interconnected by jump holes or staircase in groups of 48. OA was induced by anterior cruciate ligament transection and resection of the medial meniscus (ACLT + tMx), medial meniscal tear (MMT) or destabilization of the medial meniscus (DMM). Functional changes were characterized by continues tracking of individual activity and catwalk gait analysis. Cartilage volume and bone structure were investigated at week 20 after surgery by histology and micro-CT. Results: In the RCC, healthy rats changed cage levels 82 ± 15 times daily, reduced by 30% after ACLT + tMx (p < 0.0001). In both housing systems, the order of severity of the investigated models was ACLT + tMx > MMT > DMM in all outcome measures. Compared to Type IV, RCC housed rats developed stronger gait disturbance symptoms (ACLT + tMx; 95%CI = -15-2; p < 0.004), the cartilage volume was reduced (ACLT + tMx: 95%CI = -0.1-0.5; p < 0.0001), serum levels of the cartilage remodeling marker AGNx1 were higher (MMT; 95%CI = -53-(-6); p = 0.001), bone was denser with increased volume (ACLT + tMx; 95%CI = 0.8-7.5; p = 0.004) and joints were less flexible (ACLT + tMx; 95%CI = 3.6-14; p < 0.0001). Conclusion: Housing rats in an environment allowing increased locomotion and socialization promotes structural and functional alterations during joint instability-induced OA. This increases the assay window, improves the relevance for the human disease and enables to discriminate the models in structural and behavioral parameters.

Clinical and molecular characterization of a re-established line of sheep exhibiting hemophilia A.

BACKGROUND: Large animal models that accurately mimic human hemophilia A (HA) are in great demand for developing and testing novel therapies to treat HA. OBJECTIVES: To re-establish a line of sheep exhibiting a spontaneous bleeding disorder closely mimicking severe human HA, fully characterize their clinical presentation, and define the molecular basis for disease. PATIENTS/METHODS: Sequential reproductive manipulations were performed with cryopreserved semen from a deceased affected ram. The resultant animals were examined for hematologic parameters, clinical symptoms, and responsiveness to human FVIII (hFVIII). The full coding region of sheep FVIII mRNA was sequenced to identify the genetic lesion. RESULTS AND CONCLUSIONS: The combined reproductive technologies yielded 36 carriers and 8 affected animals. The latter had almost non-existent levels of FVIII:C and extremely prolonged aPTT, with otherwise normal hematologic parameters. These animals exhibited bleeding from the umbilical cord, prolonged tail and nail cuticle bleeding time, and multiple episodes of severe spontaneous bleeding, including hemarthroses, muscle hematomas and hematuria, all of which responded to hFVIII. Inhibitors of hFVIII were detected in four treated animals, further establishing the preclinical value of this model. Sequencing identified a premature stop codon and frame-shift in exon 14, providing a molecular explanation for HA. Given the decades of experience using sheep to study both normal physiology and a wide array of diseases and the high homology between human and sheep FVIII, this new model will enable a better understanding of HA and facilitate the development and testing of novel treatments that can directly translate to HA patients.