Versatile electrical stimulator for providing cardiac-like electrical impulses in vitro

In the perspective of reliable methods alternative to in vivo animal testing for cardiac tissue engineering (CTE) research, the versatile electrical stimulator ELETTRA has been developed. ELETTRA delivers controlled and stable cardiac-like electrical impulses, and it can be coupled to already existing bioreactors for providing in vitro combined biomimetic culture conditions. Designed to be cost-effective and easy to use, this device could contribute to the reduction and replacement of in vivo animal experiments in CTE

Versatile electrical stimulator for cardiac tissue engineering—Investigation of charge-balanced monophasic and biphasic electrical stimulations

The application of biomimetic physical stimuli replicating the in vivo dynamic microenvironment is crucial for the in vitro development of functional cardiac tissues. In particular, pulsed electrical stimulation (ES) has been shown to improve the functional properties of in vitro cultured cardiomyocytes. However, commercially available electrical stimulators are expensive and cumbersome devices while customized solutions often allow limited parameter tunability, constraining the investigation of different ES protocols. The goal of this study was to develop a versatile compact electrical stimulator (ELETTRA) for biomimetic cardiac tissue engineering approaches, designed for delivering controlled parallelizable ES at a competitive cost. ELETTRA is based on an open-source micro-controller running custom software and is combinable with different cell/tissue culture set-ups, allowing simultaneously testing different ES patterns on multiple samples. In particular, customized culture chambers were appositely designed and manufactured for investigating the influence of monophasic and biphasic pulsed ES on cardiac cell monolayers. Finite element analysis was performed for characterizing the spatial distributions of the electrical field and the current density within the culture chamber. Performance tests confirmed the accuracy, compliance, and reliability of the ES parameters delivered by ELETTRA. Biological tests were performed on neonatal rat cardiac cells, electrically stimulated for 4 days, by comparing, for the first time, the monophasic waveform (electric field = 5 V/cm) to biphasic waveforms by matching either the absolute value of the electric field variation (biphasic ES at ±2.5 V/cm) or the total delivered charge (biphasic ES at ±5 V/cm). Findings suggested that monophasic ES at 5 V/cm and, particularly, charge-balanced biphasic ES at ±5 V/cm were effective in enhancing electrical functionality of stimulated cardiac cells and in promoting synchronous contraction

Compact and tunable stretch bioreactor advancing tissue engineering implementation. Application to engineered cardiac constructs

Physical stimuli are crucial for the structural and functional maturation of tissues both in vivo and in vitro . In tissue engineering applications, bioreactors have become fundamental and effective tools for provid- ing biomimetic culture conditions that recapitulate the native physical stimuli. In addition, bioreactors play a key role in assuring strict control, automation, and standardization in the production process of cell-based products for future clinical application. In this study, a compact, easy-to-use, tunable stretch bioreactor is proposed. Based on customizable and low-cost technological solutions, the bioreactor was designed for providing tunable mechanical stretch for biomimetic dynamic culture of different engineered tissues. In-house validation tests demonstrated the accuracy and repeatability of the imposed mechanical stimulation. Proof of concepts biological tests performed on engineered cardiac constructs, based on de- cellularized human skin scaffolds seeded with human cardiac progenitor cells, confirmed the bioreactor Good Laboratory Practice compliance and ease of use, and the effectiveness of the delivered cyclic stretch stimulation on the cardiac construct maturation

An automated 3D-printed perfusion bioreactor combinable with pulsed electromagnetic field stimulators for bone tissue investigations

In bone tissue engineering research, bioreactors designed for replicating the main features of the complex native environment represent powerful investigation tools. Moreover, when equipped with automation, their use allows reducing user intervention and dependence, increasing reproducibility and the overall quality of the culture process. In this study, an automated uni-/bi-directional perfusion bioreactor combinable with pulsed electromagnetic field (PEMF) stimulation for culturing 3D bone tissue models is proposed. A user-friendly control unit automates the perfusion, minimizing the user dependency. Computational fluid dynamics simulations supported the culture chamber design and allowed the estimation of the shear stress values within the construct. Electromagnetic field simulations demonstrated that, in case of combination with a PEMF stimulator, the construct can be exposed to uniform magnetic fields. Preliminary biological tests on 3D bone tissue models showed that perfusion promotes the release of the early differentiation marker alkaline phosphatase. The histological analysis confirmed that perfusion favors cells to deposit more extracellular matrix (ECM) with respect to the static culture and revealed that bi-directional perfusion better promotes ECM deposition across the construct with respect to uni-directional perfusion. Lastly, the Real-time PCR results of 3D bone tissue models cultured under bi-directional perfusion without and with PEMF stimulation revealed that the only perfusion induced a ~ 40-fold up-regulation of the expression of the osteogenic gene collagen type I with respect to the static control, while a ~ 80-fold up-regulation was measured when perfusion was combined with PEMF stimulation, indicating a positive synergic pro-osteogenic effect of combined physical stimulation

Artery in Microgravity (AIM): Assembly, integration, and testing for a student payload for the ISS

The Artery in Microgravity (AIM) project was the first experiment to be selected for the “Orbit Your Thesis!” programme of the European Space Agency Academy. It is a 2U cube experiment that will be operated in the International Commercial Experiment (ICE) Cubes facility onboard the International Space Station. The experiment is expected to be launched on SpaceX-25 in mid-2022. The project is being developed by an international group of students from ISAE-SUPAERO and Politecnico di Torino. The objective of the experiment is to study haemodynamics in the space environment applied to coronary heart disease. The outcomes of this testbench will contribute to understanding the effects of radiation and microgravity on the circulatory system of an astronaut, specifically the behaviour in long-term human spaceflight. It will also help to ascertain the feasibility of individuals suffering from this kind of disease going to space someday. The cornerstones of the experiment are two models of 3D-printed artificial arteries, in stenotic and stented conditions respectively. Blood-mimicking fluid composed of water and glycerol is circulated through the arteries in a closed hydraulic loop, and a red dye is injected for flow visualisation. Drops of pressure and image analysis of the flow will be studied with the corresponding sensors and camera. The pH of the fluid will also be monitored to assess the effect of augmented radiation levels on the release of particles from the metallic stent. Some delays were experienced in the project due to the COVID-19 pandemic and to implement design improvements. Improvements were made to several aspects of the design including mechanics (e.g. remanufacturing the reservoir with surface treatment against corrosion, leak prevention measures), software (e.g. upgrading to Odroid-C4 and migrating the code to Python), and electronics (e.g. several iterations of the interface PCB design). This iterative process of identifying areas of concern and designing and implementing solutions has resulted in many lessons learned. The paper will outline in detail Phase D – Qualification and Production of the AIM experiment cube, with special insight on the implementation of the improvements. Previously, at the Symposium on Space Educational Activities in 2019 in Leicester, the initial phases of the design and development of the cube were presented. This year, the final flight model and the results of validation testing before launching on SpaceX-25 are presented. Lessons learned throughout the course of the project are also highlighted for students embarking on their own space-related educational activities

Innovative force sensor for indoor climbing holds – real-time measurements and data processing, design and validation

In this article, a system to measure the evolution of load in time and space during indoor climbing is described. The system is based on a set of dedicated multiaxial load cells, which measure the load on each hold of an indoor climbing wall. When the climber hangs on a hold, the load signal is read and sent to a digital acquisition and processing system. Sensor design allows for measurement of the force components applied to the climbing holds, regardless of the application point of the force on the hold. Local deformations were measured through strain gauges. Based on the electrical configuration of the strain gauges, the values of the applied forces can be computed, making the contributions to the deformation due to bending moments and torsion negligible. The sensor was designed, assuming a maximum applicable load of 200 kg without plastic deformation. The design process was based on both analytical and finite element method analyses. An experimental calibration and testing campaign was performed to validate the sensor design