Background/Purpose: Mitochondrial dysfunction is well documented in OA and has the capacity to alter chondrocyte function and viability, contributing to cartilage degeneration. Several studies have showed that chondrocytes from OA patients have mitochondrial alterations. With this background, it is important can evaluate the influence of mitochondria in the pathogenesis of OA using an in vitro model to explain the functional consequences of this association and help us to identify potential diagnostic biomarkers and/or therapeutic targets. Transmitochondrial cybrids are a useful cellular model to study the mitochondrial role in the cellular behavior, since they carry different mitochondrial variants with the same nuclear background. The aim of this work is used an in vitro model based in cybrids with mtDNA from healthy and OA donors and characterize them. Comparing the data with data obtained from human articular chondrocytes.

Methods: mtDNA Cybrids were developed using 143B.TK^–Rho-0 cell as nuclear donor, and platelets from patients N and OA. Human articular chondrocytes were obtained from patients with hip replacement. The mtDNA copy number was measured by real-time PCR method. The O₂^– production was evaluated using flow cytometry. The glucose oxidation assay was measured using D-[¹⁴C(U)]glucose during 4 h CO₂ trapping. The glycolytic activity was measure after addition of glucose, oligomycin and 2-dioxyglucose using Seahorse XFp (ECAR). The OXPHOS function was evaluated by SeaHorse XFp (OCR) after addition of oligomycin, FCCP and Rotenone/Antimycin. Appropriate statistical analyses were performed with GraphPad Prism v6.

Results: mtDNA copy number showed that OA have higher levels than N in cybrids and human chondrocytes showed the same results. The analysis of O₂^– production showed that OA had higher levels than N in both types of cells. The metabolic status analyzing glucose oxidation and total glucose cellular uptake reflected higher values in OA cybrids than N cybrids. But the analysis of glycolysis showed lower values in OA than N cybrids. The analysis of OXPHOS function showed that OA had lower basal respiration and maximal respiratory capacity than N in both types of cells.

Conclusion: In this study, we showed that OA cybrids behave differently from cybrids from healthy (N) donors, while they have a similar behavior to OA and N articular chondrocytes. This information enhances our understanding of the role of mitochondria in OA and suggests that cybrids are a possible model for the study of OA pathogenesis. All these data support that N cybrids and chondrocytes use mitochondria with more efficiency.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/develop-an-in-vitro-model-to-test-the-different-behavior-of-mtdna-in-oa-and-healthy-patients-based-on-mitochondrial-activity-and-metabolic-response/