Poster U4 - Automating Perfusion-Decellularization for Engineering Bioartificial Hearts

Introduction: Scarcity of hearts for transplant and new effective treatments for heart failure are still some of the greatest challenges modern cardiology faces today. In fact, around 4,400 patients were waiting for a heart transplant in 2021 and during 2016-2018, only 50% of the patients listed underwent a transplant by the first year (Colvin et al. 2021). In order to address the lack of hearts available for transplant, a promising engineering solution has risen in the biomedical field: A functional bioartificial heart.
Creating a bioartificial heart is a very complex task. It consists of a multi-step process that involves the use of several biological and engineering techniques as well as specialized equipment set up carefully in a sterile environment. One of the first steps of this process is the perfusion-decellularization of cadaveric hearts. It involves the flow of detergents through a heart for extended periods of time at a constant pressure in a Langerdoff system (Tang-Quan et al. 2020). Although it is a relatively closed system, the Langerdoff setup allows for air and liquid contamination. Additionally, the current perfusion-decellularization protocol is extremely labor intensive and allows for human manipulation error as it requires manual assembly, setup, maintenance and termination. To speed-up, reduce labor costs and standardize our protocol, we designed an automated perfusion-decellularization system that involves the use of a net of pumps, flow sensors, tubing and electronics to perform decellularization of heart scaffolds in the lab.

Materials and

Methods: Hardware
The system comprises both electrical and mechanical components altogether. On the electrical side, a prototype circuit board (PCB) serves as the main controller of the system and it integrates a ESP32 S3 microcontroller, motor drivers, voltage regulators and signal amplifiers. The current mechanical hardware includes a digitally controlled peristaltic pump, pressure and flow sensors for closed-loop perfusion control, eight servo-actuated valves for automatic solution swapping, and a sample collection module. These features enable precise and automated control of fluid perfusion, facilitating advanced protocols and ensuring consistent quality in our processes.
Software
The software architecture consists of a C++ firmware for the microcontroller, and a front-end Python scripted application that operates on a PC platform. Both the firmware and front-end connect with an MQTT (Internet of Things) server that enables remote operation and real-time monitoring of the experiment. Therefore, this integration facilitates efficient control of the experimental setup from any location with internet connectivity.
Experimental Validation
The individual sub-assemblies and software modules of the system have been completed and demonstrated long-term performance qualitatively for any signs of wear or dysfunction after one week of continuous operation.

Results, Conclusions, and Discussions: The sub-assemblies of the system behaved as expected. It operated continuously for 7 days without any signs of wear or tear. Additionally, the accuracy of the movement for the sample collection exhibited no noticeable positional drift during this time. Finally, the continuous pressure perfusion function demonstrated rapid responsiveness compensating variations in resistance in less than 5 seconds and stabilizing the pressure to the set threshold.
At this moment, we are in the final stages of assembling the complete system and anticipate commencing its use for our decellularization experiments in the following weeks. Using this system for bioartificial heart perfusion-decellularization, we anticipate a quality variability reduction of the acellular scaffolds optimizing our experimental procedures for future research in the lab.
References
Colvin, M. M., Smith, J. M., Ahn, Y. S., Messick, E., Lindblad, K., Israni, A. K., Snyder, J. J., & Kasiske, B. L. (2023). OPTN/SRTR 2021 Annual Data Report: Heart. American Journal of Transplantation, 23(2), S300–S378. https://doi.org/10.1016/j.ajt.2023.02.008
Tang-Quan, K. R., Xi, Y., Hochman-Mendez, C., Xiang, Q., Lee, P.-F., Sampaio, L. C., & Taylor, D. A. (2020). Gelatin Promotes Cell Retention Within Decellularized Heart Extracellular Matrix Vasculature and Parenchyma. Cellular and Molecular Bioengineering, 13(6), 633–645. https://doi.org/10.1007/s12195-020-00634-z

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