Chondro-protective effects of low intensity pulsed ultrasound

Abstract

Objectives Cartilage is a highly mechano-responsive tissue. Chondrocytes undergo a series of complex changes, including proliferation and metabolic alteration as the target of external biomechanical and biochemical stimuli. IL-1β is known to regulate chondrocyte metabolism and play an important role in the pathogenesis of osteoarthritis. The objective of this study was to employ low-intensity pulsed ultrasound (LIPUS) as a localized mechanical stimulus and assess its effects on chondrocyte migration, proliferation, metabolism, and differentiation, as well as its ability to suppress IL-1β mediated catabolism in cartilage. Methods Human cartilage explants and chondrocytes were stimulated by LIPUS in presence and absence of of IL-1β to asses cartilage degradation, chondrocytes metabolism, migration and proliferation. Western blot analyses were conducted to study IL-1β the associated NFκB pathway in chondrocytes. Results LIPUS stimulation increased the proteoglycan content in human cartilage explants and inhibited IL-1β induced loss of proteoglycans. LIPUS stimulation increased rates of chondrocyte migration and proliferation, and promoted chondrogenesis in mesenchymal stem cells. Further, LIPUS suppressed IL-1β induced activation of phosphorylation of NFκB-p65 and IκBα leading to reduced expression of MMP13 and ADAMT5 in chondrocytes. Conclusions Collectively, these data demonstrate the potential therapeutic effects of LIPUS in preventing cartilage degradation and treating osteoarthritis via a mechanical stimulation that inhibits the catabolic action of IL-1β and stimulates chondrocyte migration, proliferation, and differentiation.

Low-intensity pulsed ultrasound promotes cell motility through vinculin-controlled Rac1 GTPase activity

“…Enhanced cell migration is a widely reported response to LIPUS stimulation, occurring in several cell types including mesenchymal stem cells (Wei et al, 2014), chondrogenic progenitor cells (Jang et al, 2014), primary human endothelial cells (Katano et al, 2011), human chondrocytes (Uddin et al, 2016) and MC3T3 mouse osteoblasts (Fig. S1C) (Sawai et al, 2012).…”

Low Intensity Pulsed Ultrasound and Articular Cartilage Repair

“…LIPUS may also improve overall chondral histology [6] , while preventing or delaying excess cartilage degradation [29,33] , and in accord with early work [6] may specifically reduce the expression not only of matrix metallopeptidase-13 [29,33] , but interleukin-1B [29] , an additional catabolic degradative overexpressed enzyme found in osteoarthritis. On the other hand, in addition to clearly heightening type II collagen production in early stage osteoarthritis [4] , LIPUS applications help to reduce synovial inflammation [33] , increase chondrocyte numbers [36] , and enhance other strategies designed to promote anabolic cartilage chondrocyte repair processes [37] .…”

“…In addition to the above examples, and despite the lack of parallel clinical evidence, the past as well as the currently emerging LIPUS associated data are believed to hold considerable promise as regards cartilage repair [41,42] . In particular, very similar LIPUSrelated chondrogenic effects are seen regardless of substrate, such as mesenchymal stem cells [20] , and even among human osteoarthritic chondrocytes [19] , as well as those substrates derived from wellaccepted animal models of osteoarthritis [17,19,29] . Importantly positive metabolic outcomes have also been observed, even among osteoarthritic explants [19] and animal models of idiopathic human osteoarthritis [17] , and when normal animal activity has been permitted [21] , and among mesenchymal stem cells, LIPUS promotes chondrogenesis even in the absence of Transforming Growth Factor-B [20] , normally required to promote chondrogenesis in these cells [20] .…”

“…As mentioned previously, these mechanisms of action include, but are not limited to, an apparent reduction in matrix metalloproteinases-13 immunopositive cells [36] , downregulation of interleukin 1 [IL 1], a potent degradative enzyme responsible for considerable inflammatory damage in osteoarthritis that is not readily attenuated by standard pharmacologic interventions [61] , and the activation of the circadian Per-2 gene [32] . Another is related to its potential for stimulating chondrocyte proliferation along with heightened matrix production [19,29] . Moreover, LIPUS appears to stimulate chondrocyte proteoglycan synthesis [62] , while down regulating potent catabolic cartilage enzymes [3,29,33,47] , which can otherwise degrade one or more essential functional and structural components of the chondrocyte extracellular matrix [63] , concurrently.…”

“…Non treated explants showed signs of atrophy at 1 week, but not in treated explants where cell clusters were observed Ting et al [28] Examined the effect of LIPUS on scaffold-free dedifferentiated bovine articular cartilage chondrocytes Those tissues exposed to TGF-B3 produced increases in total collagen and glycosaminoglycan along with cartilage-specific gene expression **Uddin et al [29] Examined the specific impact of LIPUS on human cartilage cells and explants in the presence and absence of IL-1B using Western blot analysis in an effort to specifically study the cellular pathway associated with IL-1B activity LIPUS stimulation applied using a unit with a 10cm2 transducer to cells and explants cultured on 35mm plates for a 20min period per day as approved for bone healing stimulations, increased proteoglycan content as well as inhibiting IL-1B induced loss of proteoglycans Yamaguchi et al [30] An osteochondral defect was created on both femur grooves of Wistar rats. Four wks later, bone m↓ mesenchymal stromal cells (MSCs) were injected into the right knee joint MSC injection improved the cartilage repair score, and LIPUS irradiation improved BV/TV…”