Development of an electrical impedance tomography set-up for the quantification of mineralization in biopolymer scaffolds

Abstract

Objective. 3D cell cultures are becoming a fundamental resource for in-vitro studies, as they mimic more closely in-vivo behavior. The analysis of these constructs, however, generally rely on destructive techniques, that prevent the monitoring over time of the same construct, thus increasing the results variability and the resources needed for each experiment. Approach. In this work, we focus on mineralization, a crucial process during maturation of artificial bone models, and propose electrical impedance tomography (EIT) as an alternative non-destructive approach. In particular, we discuss the development of an integrated hardware/software system capable of acquiring experimental data from 3D scaffolds and reconstructing the corresponding conductivity maps. We also show how the same software can test how the measurement is affected by biological features such as scaffold shrinking during the culture. Main results. An initial validation, comprising the acquisition of both a non-conductive phantom and alginate/gelatin scaffolds with known calcium content will be presented, together with the in-silico study of a cell-induced mineralization process. This analysis will allow for an initial verification of the systems functionality while limiting the effects of biological variability due to cell number and activity. Significance. Our results show the potential of EIT for the non-destructive quantification of matrix mineralization in 3D scaffolds, and open to the possible long term monitoring of this fundamental hallmark of osteogenic differentiation in hybrid tissue engineered constructs.

Design of a custom-made device for real-time optical measurement of differential mineral concentrations in three-dimensional scaffolds for bone tissue engineering

“…Based on these results the custom-made spectrometer device appears as a useful option to perform real-time/in-line analysis of TEed constructs. Its cost and performance make it competitive with other recently proposed non-destructive approaches [26]. Furthermore, the small dimensions allow us to consider the device as a component that can be easily integrated on board of recently prototyped bioreactor systems [27][28][29][30][31], for the monitoring of the TEed constructs during their conditioning.…”

Non-destructive monitoring of 3D cell cultures: new technologies and applications

“…As detailed in the previous sections, these methods are largely connected with cell destructive processing. While the alternative approaches already described maintain their general validity, other methods specific for the evaluation of changes in matrix properties have been proposed for the study of artificial bone substitutes ( Cortesi et al, 2021b ; Lovecchio et al, 2022 ; Arunngam et al, 2018 ). They are based on either EIT or spectroscopic techniques and aim at quantifying different calcium-based components that are typical of cell-induced mineralization.…”

“…Our works on the topic ( Cortesi et al, 2021b ; Lovecchio et al, 2022 ) rely on a different experimental model that grants better reproducibility and a higher level of control. Indeed, the amount of minerals produced by the cells is highly dependent on the type of cells and the experimental protocol employed.…”

“…To overcome this issue, we used alginate-based scaffolds that can be polymerised in presence of defined amounts of calcium carbonate to produce phantoms with highly reproducible mineral content. This difference could be quantified with either a custom-made spectrometer ( Lovecchio et al, 2022 ) or an EIT system ( Cortesi et al, 2021b ) ( Fig. 5 ).…”

Advances of deep learning in electrical impedance tomography image reconstruction

“…Furthermore, You et al first reported the case of retroperitoneal hemorrhage EIT monitoring in patients with renal trauma ( You et al, 2013 ), and Liu et al reported the first study on non-invasive monitoring of cerebral blood volume during total aortic arch replacement ( Liu et al, 2019 ). In addition to the abovementioned fields, EIT has extensive applications in biomedical areas, such as cell culture monitoring ( Yang et al, 2019 ; Schwarz et al, 2020 ; Liu et al, 2022b ) and bioimpedance analysis ( Cortesi et al, 2021 ). These studies fully demonstrate that EIT, as a new medical imaging technology, is gradually becoming a powerful supplement to traditional medical imaging technology.…”