16.1.1 - Continuous Low-Intensity Ultrasound Preserves Chondrogenesis of MSCs and Mitochondrial Potential While Inhibiting NFκB Activation
- A. Subramanian (Huntsville, US)
- A. Subramanian (Huntsville, US)
- S. Bhogoju (Huntsville, US)
- S. Khan (Huntsville, US)
Abstract
Purpose
Dysregulation of the anabolic processes in a proinflammatory joint environment coupled with impeded chondrogenic differentiation of mesenchymal stromal cells (MSCs) led to inferior cartilage repair outcomes. The preponderance of proinflammatory cytokines activated nuclear factor kappa B (NFκB) impedes the chondrogenesis of MSCs. Strategies that minimize the deleterious effects of activated NFκB while promoting MSC chondrogenesis are of interest. The present study establishes the ability of continuous low-intensity ultrasound (cLIUS) to preserve MSC chondrogenesis impacted by a proinflammatory environment.
Methods and Materials
MSCs were seeded in alginate: collagen hydrogels and cultured for 21-days in ultrasound (US)-assisted bioreactor 14 kPa (4-applications/day) in the presence of IL1β and evaluated by qRT-PCR and immunofluorescence (IF). The differential expression of markers associated with the NFκB pathway under cLIUS was evaluated upon a single exposure of cLIUS and assayed by qRT-PCR, IF, WB, and tetramethylrhodamine methyl ester (TMRM) assay was used to assess the mitochondrial potential under IL1β and cLIUS treatment. Study groups included appropriate non-cytokine treated and non-cLIUS treated controls (Fig.1B).
Results
Chondroinductive potential of cLIUS was preserved as noted by the increased expression of SOX9 and deposition of collagen II (Fig. 2A-I & III). cLIUS extended its chondroprotective effects by stabilizing the NFκB complex in the cytoplasm via engaging the IκBα feedback mechanism, thus preventing its nuclear translocation (Fig. 2A-II). cLIUS acted as a mitochondrial protective agent by restoring the mitochondrial potential and the mitochondrial mRNA expression in a proinflammatory environment (Fig. 2C-VI). Altogether, our results demonstrated the potential of cLIUS for cartilage repair and regeneration under proinflammatory conditions (Fig.1A).
Conclusion
This study establishes the potential of cLIUS to improve and enhance outcomes of in vivo cartilage repair therapies. Translation of promising in vitro findings with cLIUS requires an understanding of the cLIUS propagation in the joint space along with optimal transducer settings.