assembly and priming of the 3d-printed bioreactor for perfusion culture

A Novel 3D Printed Bioreactor for Ex Vivo Culture of Blood Vessels in Perfusion

The vascular wall exists in a reactive steady state, which ensures both responsivities to external stimuli (i.e., change of pressure, vasoconstrictors) and a consistent non-activating surface preventing blood coagulation and inflammatory cell infiltration1. In response to aging- and lifestyle-dependent stimuli and upon direct damage, the vascular wall activates remodeling processes such as restenosis and atherosclerosis, which are known contributors to common cardiovascular diseases (CVDs), such as ischemic stroke and myocardial infarction2. While interventional approaches such as percutaneous revascularisation and stenting are available to tackle advanced manifestations of vascular disease, these are known to provoke further vascular damage, often leading to recurrence. In addition, only limited preventative and early-stage solutions are available. Understanding the mechanisms maintaining vascular wall homeostasis and driving its dysfunction is at the heart of developing new cures3.
Despite the constant development and advances in molecular biology and tissue engineering, animal studies remain a crucial component of vascular biology studies. In vivo animal studies have provided enormous insight into the mechanisms of vascular homeostasis and pathology; however, these procedures are costly, have relatively low throughput, and pose substantial ethical issues. In addition, small animals are poorly representative of human vascular physiology, and larger animal experiments are vastly more expensive and create further ethical considerations4,5. With the increasing demand for pharmaceutical and medical solutions for a rapidly aging population, the downsides of animal use are magnified, impacting the reproducibility, reliability, and transferability of results to patient care6.
In vitro systems offer a simplified platform to study basic mechanisms but fail to recapitulate the complexity of the whole tissue, the interactions between cells and the extracellular matrix, and the mechanical forces, which are critical determinants in the development of vascular diseases7.
Ex vivo studies performed on whole tissues maintained in artificially controlled environments mimic the in vivo complexity while enabling relatively high-throughput investigations8. Given the ability to closely control the culture conditions and environment, ex vivo models allow a broad range of complex studies and provide a suitable alternative to reduce the use of animal procedures in vascular biology. Static vascular ring cultures offered interesting insights but failed to incorporate the crucial hemodynamic element9. Indeed, the study of the vascular system ex vivo poses specific challenges related to the many dynamic forces which apply to the cells within the blood vessel wall. Stimuli such as luminal flow, turbulence, shear stress, pressure, and wall deformation significantly impact tissue pathophysiology10,11,12.
Perfusion bioreactors are essential for studying vascular homeostasis and remodeling in response to injury or hemodynamic changes13. Furthermore, perfusion culture can be used to improve the maturation and durability of tissue-engineered blood vessels (TEBVs), providing suitable alternatives for vascular grafts14.
Commercially available perfusion bioreactors are limited in flexibility and adaptability and are costly. Many of the existing in-house developed bioreactors are instead difficult to replicate in other labs, due to the limited descriptions and unavailability of specially made components7,8,9,10,11,12. To overcome these limitations, we have recently developed a new bioreactor (EasyFlow), which is economical to produce, accommodates a range of tissues, and enables relatively simple modifications to adapt to different research demands13. The insert is 3D printed and fits as in a lid of a standard 50 mL centrifuge tube. Its modular design and 3D printing manufacture make it accessible and reproducible across different labs, as well as easily modifiable to adapt to different scientific needs. This protocol describes the assembly and basic operation of the bioreactor system in an arterial perfusion setting.

Author Spotlight: EasyFlow - An Economical and Adaptable Perfusion Bioreactor for Large Blood Vessel Culture 

Ex Vivo Perfusion Culture of Large Blood Vessels in a 3D Printed Bioreactor

We developed a simple cost-effective and adaptable bioreactor for the culture of blood vessels in vitro. The application of physiological flow and pulsatile forces to blood vessels ensures that the cells within the tissue remain viable. The application of bioreactors, such as the one we described here, enable the culture of blood vessels ex vivo and reduces the reliance on animal experiments in research.The application of hemodynamic forces is crucial to maintain a healthy blood vessel in culture, while profusion bioreactors are a great solution to achieve this dynamic environment. Systems described in the existing literature are often challenging to replicate, expensive, and not easy to adapt. We have developed a new perfusion system titled EasyFlow.This system is economic to produce, accommodates a different range of tissues, and is simple to modify so researchers can adapt it to their experimental needs. The production is open source, based on a 3D model, and is accessible through the paper. Also, it can be adapted to the needs of the research based on this 3D model.EasyFlow is currently being employed to test mechanism of vascular repair, such as stem cells or biomaterial-based therapies. We also aim to use this bioreactor to induce the maturation of tissue-engineered blood vessels.

Watch this Scientific Journal Video about Assembly and Priming of the 3D-Printed Bioreactor for Perfusion Culture at JoVE.com

Assembly and Priming of the 3D-Printed Bioreactor for Perfusion Culture  

Begin assembling the bioreactor under laminar flow by first assembling the two 3D printed easy flow inserts. Then using one insert as the reservoir, and the other as the reaction chamber, proceed to assemble the perfusion system. Attach two connected three-way valves to the reservoir R1 port using a system tube equipped with a one-way valve.Connect the resulting outlet with the pump head. Then connect the pump head to the reaction chamber's C4 port using similar tubing with a one-way valve. Next, connect the reaction chamber port C1 via soft wall tubing to the resistance channel with a smaller inner diameter.Create a perfusion return channel by extending the resistance channel with the system tubing, and closing the luminal circulation loop by connecting to the reservoir at R5.Create an overflow channel by connecting the reaction chamber port C3 to the reservoir port R3 using system tubing, Attach a ventilator filter through R2.Construct a pressure dampener by connecting a syringe filled with air and media to the reaction chamber C6.Using a perfusion media, prime the system through the media exchange ports and the reservoir.

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Research

JoVE Journal

Bioengineering

487 Views. Begin assembling the bioreactor under laminar flow by first assembling the two 3D printed easy flow inserts. Then using one insert as the reservoir, and the other as the reaction chamber, proceed to assemble the perfusion system. Attach two connected three-way valves to the reservoir R1 port using a system tube equipped with a one-way valve.Connect the resulting outlet with the pump head. Then connect the pump head to the reaction chamber's C4 port using similar tubing with a one-way v...

Video: Assembly and Priming of the 3D-Printed Bioreactor for Perfusion Culture  

Vascular disease forms the basis of most cardiovascular diseases (CVDs), which remain the primary cause of mortality and morbidity worldwide. Efficacious surgical and pharmacological interventions to prevent and treat vascular disease are urgently needed. In part, the shortage of translational models limits the understanding of the cellular and molecular processes involved in vascular disease. Ex vivo perfusion culture bioreactors provide an ideal platform for the study of large animal vessels (including humans) in a controlled dynamic environment, combining the ease of in vitro culture and the complexity of the live tissue. Most bioreactors are, however, custom manufactured and therefore difficult to adopt, limiting the reproducibility of the results. This paper presents a 3D printed system that can be easily produced and applied in any biological lab, and provides a detailed protocol for its setup, enabling users&#39; operation. This innovative and reproducible ex vivo perfusion culture system enables the culture of blood vessels for up to 7 days in physiological conditions. We expect that adopting a standardized perfusion bioreactor will support a better understanding of physiological and pathological processes in large animal blood vessels and accelerate the discovery of new therapeutics.

This protocol presents the setup and operation of a newly developed, 3D printed bioreactor for the ex vivo culture of blood vessels in perfusion. The system is designed to be easily adopted by other users, practical, affordable, and adaptable to different experimental applications, such as basic biology and pharmacological studies.

Vascular disease forms the basis of most cardiovascular diseases (CVDs), which remain the primary cause of mortality and morbidity worldwide. Efficacious ...

Perfusion Culture of Blood Vessels in the 3D-Printed Bioreactor

To prepare the sample for perfusion culture using the 3D-printed bioreactor. In a laminar flow cabinet, place the isolated porcine carotid artery samples in cold transport media. Using a scalpel blade, remove excess connective tissue and trim the ends of the tissue.Then wash the tissue twice in cold transport media. Next, place the tissue in transport media on an orbital shaker for a minimum of 30 minutes for a thorough final washing. After that, connect a non-branching segment of the washed artery to the fabricated bioreactor system using two barbed lure connections.And secure it using a vessel bond made of vascular silicone ties. Using a small syringe attached to the first lure connection, gently flow media through the artery to ensure its patency. After securing the artery to the fabricated insert, fill the reaction space with perfusion media.Next, carefully fill the luminal circulation loop with media, removing any remaining air from the system. Lastly, connect the reaction space to the assembled perfusion system, completing the circulation. To perform the perfusion culture, place the perfusion system in an incubator.After connecting it to a peristaltic pump, connect any additional acquisition systems, such as pressure sensors. Allow the system to equilibrate overnight with a low media flow rate of approximately 10 to 15 milliliters per minute. The following day, incrementally increase the flow until a final flow rate of 35 milliliters per minute is achieved.Every three days, replace 50%of the media by connecting one syringe with fresh media to the media exchange port closer to the pump and an empty syringe to the port closer to the reservoir to collect the spent medium. After the experiment, using sterile surgical scissors, harvest the tissue from the reaction chamber by trimming the tissue ends connected to the bioreactor. Confocal imaging using endothelial and smooth muscle-specific markers revealed that the normal structure of an artery was well preserved and maintained throughout, starting from the time of harvest, to cleaning and processing, and even after perfusion culture.However, incorrect handling during processing resulted in the loss of the endothelium ahead of the culture, and the application of non-physiological culture conditions like abrupt initiation of high flow showed luminal damage. Histological evaluation of the tissue using hematoxylin and eosin staining and immunofluorescence staining at the time of harvest and after seven days of perfusion culture revealed that the morphology and overall distribution of the cells in the vessel wall were maintained throughout.