Millimeter wave treatment inhibits the mitochondrion-dependent apoptosis pathway in chondrocytes

Abstract

Abstract. Millimeter wave (MW) is an electromagnetic wave with a wavelength between 1 and 10 mm and a frequency of 30-300 GHz that causes multiple biological effects, both locally and globally. MW has been widely used in clinical medicine. Although our previous work demonstrated that MW is capable of inhibiting sodium nitroprussiate (SNP)-induced apoptosis in chondrocytes, the precise mechanism of the antiapoptotic activity remains to be elucidated. The purpose of this study was to investigate the effects of MW in SNP-induced apoptotic chondrocytes. Sprague Dawley rat chondrocytes were isolated and cultured, and the cells were counted. Cell viability was evaluated using MTT assay. Cells were then treated with SNP and MW, and flow cytometry was used to detect apoptosis. Our results showed that MW treatment inhibited a SNP-induced mitochondrion-dependent pathway of apoptosis. MW treatment inhibited the loss of plasma membrane asymmetry (externalization of phosphatidylserine), collapse of mitochondrial membrane potential, and activation of caspase-9 and caspase-3. Taken together, the results indicate that MW inhibits the mitochondrion-dependent pathway of apoptosis in chondrocytes and this may, in part, explain its clinical effect in the treatment of osteoarthritis.

Oxidative Stress Induces Chondrocyte Apoptosis through Caspase-Dependent and Caspase-Independent Mitochondrial Pathways and the Antioxidant Mechanism of Angelica Sinensis Polysaccharide

“…Oxidative stress plays an important role in the degradation and oxidation of cartilage ECM and triggers apoptosis of chondrocyte, which is considered to be the common molecular basis for the initiation and subsequent progress of OA. During the development of OA, chondrocytes produce excessive ROS, owing to the destruction of which, the degeneration of chondrocyte coexists with oxidative stress [ 4 , 7 , 32 ]. In our experiments, we chose intracellular ROS, MDA, and CAT as indicators of oxidative stress.…”

“…Since articular cartilage is vascularized, the regeneration after injury or degenerative changes is very limited [ 4 ]. Although the underlying mechanism has not been fully elucidated, there is considerable evidence that chondrocyte apoptosis is associated with the characteristic cartilage degradation in osteoarthritis (OA) [ 4 – 7 ]. Chondrocyte apoptosis alters the synthesis of the cartilage matrix, leading to cartilage degeneration and destruction, and finally to OA.…”

“…A wide range of signals can trigger the intrinsic pathway, including oxidative stress [ 6 , 18 ]. Chondrocyte apoptosis ultimately leads to the failure of cartilage matrix renewal, as chondrocyte is the only resident cell responsible for synthesizing and maintaining ECM molecules in articular cartilage [ 3 , 4 , 10 ]. Therefore, it is necessary to elucidate the molecular pathway of chondrocyte apoptosis in OA [ 19 ].…”

Millimeter Wave Treatment Inhibits Apoptosis of Chondrocytes via Regulation Dynamic Equilibrium of Intracellular Free Ca2+

“…The millimeter wave detecting head was positioned 30 mm above the cultured cells in the MW treatment group. The chondrocytes were placed around the probe within a 20 mm radius and within the radiation area of (33.2 ± 3) × (45.6 ± 4) mm [ 19 ]. Following millimeter wave treatment, the apoptotic rate of the chondrocytes was examined by flow cytometry (FCM) using Annexin V-FITC/PI and the mitochondrial membrane potential (ΔΨ m ) by FCM analysis with JC-1 staining.…”

“…Staining was performed according to the manufacturer's instructions, as previously described [ 21 ]. Four cell populations were identified according to the following interpretations: viable population in the lower-left quadrant (PI-negativity and FITC-negativity signals), early apoptotic population in the lower-right quadrant (PI-negativity and FITC-positivity signals), necrotic population in the upper-left quadrant (PI-positivity and FITC-negativity signals), and late apoptotic or necrotic population in the upper-right quadrant (PI-positivity and FITC-positivity signals) [ 19 ].…”