Early Signs of Bone and Cartilage Changes Induced by Treadmill Exercise in Rats

Abstract

This study aims to investigate the earliest alterations of bone and cartilage tissues as a result of different exercise protocols in the knee joint of Wistar rats. We hypothesize that pretraining to a continuous intense running protocol would protect the animals from cartilage degeneration. Three groups of animals were used: (i) an adaptive (pretraining) running group that ran for 8 weeks with gradually increasing velocity and time of running followed by a constant running program (6 weeks of 1.12 km/hour running per day); (ii) a non-adaptive running (constant running) group that initially rested for 8 weeks followed by 6 weeks of constant running; and (iii) a non-running (control) group. At weeks 8, 14, and 20 bone and cartilage were analyzed. Both running groups developed mild symptoms of cartilage irregularities, such as chondrocyte hypertrophy and cell clustering in different cartilage zones, in particular after the adaptive running protocol. As a result of physical training in the adaptive running exercise a dynamic response of bone was detected at week 8, where bone growth was enhanced. Conversely, the thickness of epiphyseal trabecular and subchondral bone (at week 14) was reduced due to the constant running in the period between 8 and 14 weeks. Finally, the intermediate differences between the two running groups disappeared after both groups had a resting period (from 14 to 20 weeks). The adaptive running group showed an increase in aggrecan gene expression and reduction of MMP2 expression after the initial 8 weeks running. Thus, the running exercise models in this study showed mild bone and cartilage/chondrocyte alterations that can be considered as early-stage osteoarthritis. The pretraining adaptive protocol before constant intense running did not protect from mild cartilage degeneration.

Assessment of nanoindentation in stiffness measurement of soft biomaterials: kidney, liver, spleen and uterus

“…Piuma nanoindentation technology has been widely used in research on biomaterial stiffness of hard animal organs, for example in bone 25 , in ear, ala nasi, and septum on both the cellular and the extracellular matrix (ECM) levels 24 , 26 , in the knee joint 22 , in articular cartilage 23 . Other examples are human donor cornea 27 , fibrotic intestinal tissue 30 , pancreatic acellular scaffolds 31 , soft plates 28 and particularly calcified aneurysmal abdominal aortas 29 .…”

“…Piuma nanoindenter is one of these technologies to be used to study elastic property of biomaterials. This technique has been widely used to test passive mechanical properties of hard biosamples, such as bone and cartilage 22 – 26 . However, so far there are only very few studies 27 – 31 which used the Nanoindentation technology to study organ stiffness of soft biomaterials, such as the kidney, liver, spleen and uterus samples.…”

Ultrasound and clinical findings in the metacarpophalangeal joint assessment of show jumping horses in training

“…These results can be explained once it is known that exercise causes deleterious effects on the synovial membrane, such as thickening, increased vascularization and synovial proliferation [28,29]. Furthermore, pro-inflammatory molecules are released into the synovial fluid of horses subjected to exercise [28,29], and bone remodeling and chondral degradation can also be observed [12].…”

“…The lameness scores also increased over time. The changes described in the literature resulting from the imposition of exercise, such as lameness, positive responses on the flexion test, ultrasound changes in the subchondral bone and chondral tissue and increased vascularization [7,8,12,27,29,35], were increasingly observed from T0 to T2. Thus, more studies need to be conducted to understand the potential of joint recovery and prevent constant degradation, taking into account the amount of training imposed and possible therapeutic interventions.…”

“…Most athletes can adjust to exercise regimens or increases in exercise intensity. However, the articular cartilage seems unable to completely recover from constant trauma resulting from exercise and can enter an inflammatory and degenerative cycle that culminates in clinical and progressive presentations of the disease [8,11,12]. Therefore, a combination of diagnostic tools is important for detecting and following up early changes [9,13].…”