High resolution monitoring of valvular interstitial cell driven pathomechanisms in procalcific environment using label-free impedance spectroscopy

Julia Böttner; Sarah Werner; Lukas Feistner; Tina Fischer-Schaepmann; Katherina Neussl; Michael A Borger; Holger Thiele; Petra Büttner; Florian Schlotter

doi:10.3389/fcvm.2023.1155371

High resolution monitoring of valvular interstitial cell driven pathomechanisms in procalcific environment using label-free impedance spectroscopy

Front Cardiovasc Med. 2023 Jun 20:10:1155371. doi: 10.3389/fcvm.2023.1155371. eCollection 2023.

Authors

Julia Böttner¹, Sarah Werner¹, Lukas Feistner¹, Tina Fischer-Schaepmann¹, Katherina Neussl¹, Michael A Borger¹, Holger Thiele¹, Petra Büttner¹, Florian Schlotter¹

Affiliation

¹ Department of Cardiology, Heart Center Leipzig at University of Leipzig, Leipzig, Germany.

Abstract

Introduction: Fibro-calcific aortic valve disease has high prevalence and is associated with significant mortality. Fibrotic extracellular matrix (ECM) remodeling and calcific mineral deposition change the valvular microarchitecture and deteriorate valvular function. Valvular interstitial cells (VICs) in profibrotic or procalcifying environment are frequently used in vitro models. However, remodeling processes take several days to weeks to develop, even in vitro. Continuous monitoring by real-time impedance spectroscopy (EIS) may reveal new insights into this process.

Methods: VIC-driven ECM remodeling stimulated by procalcifying (PM) or profibrotic medium (FM) was monitored by label-free EIS. Collagen secretion, matrix mineralization, viability, mitochondrial damage, myofibroblastic gene expression and cytoskeletal alterations were analyzed.

Results and discussion: EIS profiles of VICs in control medium (CM) and FM were comparable. PM reproducibly induced a specific, biphasic EIS profile. Phase 1 showed an initial impedance drop, which moderately correlated with decreasing collagen secretion (r = 0.67, p = 0.22), accompanied by mitochondrial membrane hyperpolarization and cell death. Phase 2 EIS signal increase was positively correlated with augmented ECM mineralization (r = 0.97, p = 0.008). VICs in PM decreased myofibroblastic gene expression (p < 0.001) and stress fiber assembly compared to CM. EIS revealed sex-specific differences. Male VICs showed higher proliferation and in PM EIS decrease in phase 1 was significantly pronounced compared to female VICs (male minimum: 7.4 ± 4.2%, female minimum: 26.5 ± 4.4%, p < 0.01). VICs in PM reproduced disease characteristics in vitro remarkably fast with significant impact of donor sex. PM suppressed myofibroblastogenesis and favored ECM mineralization. In summary, EIS represents an efficient, easy-to-use, high-content screening tool enabling patient-specific, subgroup- and temporal resolution.

Keywords: FCAVD; apoptosis; calcification; electrochemical impedance spectroscopy (EIS); extracellular matrix (ECM).

Grants and funding

The Open Access Publishing Fund of Leipzig University supported by the German Research Foundation within the program Open Access Publication Funding supported this publication.