Hydrostatic pressure-generated reactive oxygen species induce osteoarthritic conditions in cartilage pellet cultures

Abstract

Osteoarthritis (OA) is one of the most common causes of disability and represents a major socio-economic burden. Despite intensive research, the molecular mechanisms responsible for the initiation and progression of OA remain inconclusive. In recent years experimental findings revealed elevated levels of reactive oxygen species (ROS) as a major factor contributing to the onset and progression of OA. Hence, we designed a hydrostatic pressure bioreactor system that is capable of stimulating cartilage cell cultures with elevated ROS levels. Increased ROS levels in the media did not only lead to an inhibition of glycosaminoglycans and collagen II formation but also to a reduction of already formed glycosaminoglycans and collagen II in chondrogenic mesenchymal stem cell pellet cultures. These effects were associated with the elevated activity of matrix metalloproteinases as well as the increased expression of several inflammatory cytokines. ROS activated different signaling pathways including PI3K/Akt and MAPK/ERK which are known to be involved in OA initiation and progression. Utilizing the presented bioreactor system, an OA in vitro model based on the generation of ROS was developed that enables the further investigation of ROS effects on cartilage degradation but can also be used as a versatile tool for anti-oxidative drug testing.

Hydrostatic Pressure Regulates Oxidative Stress through microRNA in Human Osteoarthritic Chondrocytes

“…Among them, Young et al [25] observed an increased production of ROS, as hydrogen peroxide and hydroxyl radicals, after applying 24 h of static compression ranged from 40 to 120 psi at porcine chondrocytes. A similar increase of ROS species was observed by Rieder et al [13] upon the application, at human adipose tissue derived stromal cells, of 4 h of intermittent stimulation of 0 and 4 bars for 5 consecutive days/week for 21 days. The results of our study partially sustain these data even though the experimental protocols are not comparable.…”

“…In OA, the redox balance has lost and the excessive ROS formation participates to alter gene expression and promotes genomic instability, exacerbating cartilage destruction, synovitis, and apoptosis [21][22][23]. It has been reported an association between mechanical stress and the regulation of oxidant/antioxidant system, even if, data from the literature are poor [13,[24][25][26]. Among them, Young et al [25] observed an increased production of ROS, as hydrogen peroxide and hydroxyl radicals, after applying 24 h of static compression ranged from 40 to 120 psi at porcine chondrocytes.…”

“…At the cellular level, a dynamic physiological compression promotes chondrocyte proliferation and activity, whereas injurious static stress induces opposing, detrimental effects on cell anabolism reducing the synthesis of extracellular matrix (ECM) components [6][7][8]. A number of in vitro studies reported the role of hydrostatic pressure (HP) as modulators of morphology and metabolism of chondrocytes; the effects of HP depended of magnitude, duration, and frequency of loading [7,[9][10][11][12][13]. Interestingly, preliminary experiments on human OA chondrocyte cultures demonstrated the ability of HP to modify the expressional levels of some microRNAs (miRNA), involved in the pathogenesis of OA, and to regulate oxidative stress balance [14][15][16].…”

“…Furthermore, ROS overproduction participates to exacerbate synovitis and to release catabolic cytokines such as interleukin (IL)-1β and tumor necrosis factor alfa (TNF)-α; on the other hand, inflamed synovial cells stimulate the synthesis of newly ROS, creating a vicious circle [22,23]. Mechanical load seems to be effective in the modulation of oxidant/antioxidant system even if the current data available from the literature are scarce and controversial [13,[24][25][26].…”

Influence of the Mechanical Environment on the Regeneration of Osteochondral Defects

“…HP appears to affect hypertrophic genes, increasing Col I, Col X and MMP13 (Ogawa et al, 2009 , 2015 ; Li et al, 2016 ). Conversely, other studies revealed decreasing levels of Col I and Col X under IHP (Vinardell et al, 2012 ; Saha et al, 2017 ; Rieder et al, 2018 ). Freeman et al ( 2017 ) demonstrated that HP without any external growth factors resulted in enhanced chondrogenesis along with reduction in hypertrophic markers.…”