Continuous Low-Intensity Ultrasound Preserves Chondrogenesis of Mesenchymal Stromal Cells in the Presence of Cytokines by Inhibiting NFκB Activation

Abstract

Proinflammatory joint environment, coupled with impeded chondrogenic differentiation of mesenchymal stromal cells (MSCs), led to inferior cartilage repair outcomes. Nuclear translocation of phosphorylated-NFκB downregulates SOX9 and hinders the chondrogenesis of MSCs. Strategies that minimize the deleterious effects of NFκB, while promoting MSC chondrogenesis, are of interest. This study establishes the ability of continuous low-intensity ultrasound (cLIUS) to preserve MSC chondrogenesis in a proinflammatory environment. MSCs were seeded in alginate:collagen hydrogels and cultured for 21 days in an ultrasound-assisted bioreactor (5.0 MHz, 2.5 Vpp; 4 applications/day) in the presence of IL1β and evaluated by qRT-PCR and immunofluorescence. The differential expression of markers associated with the NFκB pathway was assessed upon a single exposure of cLIUS and assayed by Western blotting, qRT-PCR, and immunofluorescence. Mitochondrial potential was evaluated by tetramethylrhodamine methyl ester (TMRM) assay. The chondroinductive potential of cLIUS was noted by the increased expression of SOX9 and COLII. cLIUS extended its chondroprotective effects by stabilizing the NFκB complex in the cytoplasm via engaging the IκBα feedback mechanism, thus preventing its nuclear translocation. cLIUS acted as a mitochondrial protective agent by restoring the mitochondrial potential and the mitochondrial mRNA expression in a proinflammatory environment. Altogether, our results demonstrated the potential of cLIUS for cartilage repair and regeneration under proinflammatory conditions.

3D in-vitro cultures of human bone marrow and Wharton’s jelly derived mesenchymal stromal cells show high chondrogenic potential

“…Moreover, MSCs could modulate microenvironment composition as described in myelodysplasia, where they can contribute to hematopoietic stem cell growth inhibition by secretion of pro-inflammatory cytokines, especially transforming growth factor-beta (TGF-β) ( Patel et al, 2021 ). Other cytokines and growth factors are important in modulating chondrogenesis in health and disease, as pro-inflammatory cytokines, such as interleukin (IL)-1β, that induces chondrocyte-mediated ECM proteolysis, or IL-6, can significantly reduce proliferation potential of chondrocytes and favor osteoarthritis events ( Zhou et al, 2018 ; Razmara et al, 2019 ; Jafri et al, 2020a ; Bhogoju et al, 2022 ). Conversely, anti-inflammatory cytokines, such as IL-4 and IL-10, are upregulated by BM-MSC models, induce physiological cartilage turnover over osteoarthritis events, and reduce inflammatory processes of the synovia ( Jafri et al, 2020b ).…”