Effects of low‐intensity ultrasound (LIUS) stimulation on human cartilage explants

Abstract

Objective: To evaluate the effects of low-intensity ultrasound (LIUS) stimulation on the anabolic state of human cartilage from patients with osteoarthritis (OA). Methods: Explant cultures of human OA cartilage were stimulated for 10 min every day for 7 consecutive days using continuous-wave sonication at a frequency of 1 MHz with spatial and temporal average intensities of 0 (control), 40, 200, 500, or 700 mW/cm 2 . The effects of LIUS on cell proliferation were evaluated by 3 H-thymidine incorporation. Proteoglycan synthesis was evaluated by the incorporation of 35 S-sulfate and by Safaranin O staining. Collagen synthesis was evaluated by 3 H-proline incorporation and immunohistochemistry. Results: At an intensity of 200 mW/cm 2 , LIUS treatment induced the expression of collagen type II and proteoglycan measured by the incorporation of radioactivity and specific staining of the cartilage explants. However, the expression decreased again at the higher intensities of 500 or 700 mW/cm 2 . Ultrasound had no stimulatory effect on cell proliferation at any intensity. Conclusion: LIUS has anabolic effects on human cartilage in explant cultures, indicating a potentially important method for the repair of osteoarthritic cartilage.Osteoarthritis (OA) is the most common joint disease and is characterized by progressive joint destruction, ultimately leading to the need to replace major joints. Although the precise pathological mechanism has not yet been defined, changes in the function of the chondrocytes are thought to be the main cause of the pathology of OA, particularly the imbalance between the anabolism and the catabolism of the extracellular matrix produced from chondrocytes. Methods to increase synthesis of the cartilage matrix and inhibit its degradation may therefore provide effective treatments for OA.Ultrasound (US) has been used extensively in diagnostic applications (1, 2) and there has recently been increasing interest in its therapeutic use for various musculoskeletal disorders. Several studies have shown that low-intensity US (LIUS) is effective in regenerating injured tissues, including muscles (3, 4) and bones (5-9). In particular, LIUS has been shown to enhance the healing of fractured bones by inducing chondrocyte proliferation (7,9). When applied to a monolayer culture of human chondrocytes, LIUS also increased cellular proliferation and matrix synthesis (10). In animal studies, LIUS stimulation in both bone fractures and cartilage resulted in increased expression of proteoglycan or type II collagen rather than that of bone formation factors such as transforming growth factor-b (TGF-b), osteocalcin, alkaline phosphatase, and a1(I)-procollagen, hence protecting the collagen matrix and preventing the destruction or degradation of cartilage (11-13). However, the effects of LIUS treatment on chondrocyte proliferation and the expression of matrix proteins such as proteoglycan and collagen type II have not been clearly shown in intact human cartilage.In this study, we evaluated the LIUS effects on the ana...

Low‐intensity Ultrasound Stimulation Enhances Chondrogenic Differentiation in Alginate Culture of Mesenchymal Stem Cells

“…TGF-β3 was used instead of TGF-β1 because it was previously shown to have better activity to induce chondrogenic differentiation of MSCs (9). The LIUS stimulation was performed as described previously with some modifications (21). Briefly, LIUS was treated for 10 min every 12 h for 1 or 2 weeks at a frequency of 1 MHz and an intensity of 200 mW/cm 2 in a continuous-wave fashion.…”

“…LIUS is also reported to enhance repair of articular cartilage in animal model of cartilage defect (16,17). In cultured chondrocytes in vitro, LIUS stimulation enhances the synthesis of matrix proteins such as collagen type II and proteoglycans depending on the culture condition and LIUS intensity (18)(19)(20)(21)(22).…”

Effect of ultrasound on human umbilical cord peri-vascular cells

“…The precise cellular mechanisms that mediate the observed therapeutic action of LIPUS are still not fully understood [36][37][38] .…”

Low-Intensity Ultrasound (LIUS) as an Innovative Tool for Chondrogenesis of Mesenchymal Stem Cells (MSCs)

“…The LIUS parameters and treatment conditions were optimized based on our studies using chondrocytes. 20,21,26,27 In alginate culture of rabbit MSCs, LIUS stimulated synthesis of cartilage matrix, formation of lacunae, and enhanced expression of chondrogenic marker genes such as aggrecan, type II collagen and Sox-9 after one or two weeks of culture. 14 Similar results of the LIUS effect were obtained in vitro in alginate culture of human MSCs (Fig.…”

“…[9][10][11][12][13][14][15][16] Among these mechanical stimulations, LIUS is of particular interest because it is simple, cost-effective and already proven to activate chondrocyte phenotypes in vitro [17][18][19][20][21][22] and improve cartilage repair in animal models. 23,24 This review will introduce findings by other groups and ours on the LIUS effect on MSCs during the chondrogenic differentiation and will discuss some of the issues regarding its mechanism and future applications.…”