New Findings

Allevi Author - Valentine's Day Edition: GWU Bioprints Heart Tissue

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George Washington University joins the #AlleviAuthor club with their new paper titled, “Use of GelMA for 3D printing of cardiac myocytes and fibroblasts” and published in Journal of 3D Printing in Medicine.

First let’s review some basics about your heart! Heart tissue is composed of two main cell types; cardiac fibroblasts (CFB) & cardiomyocytes (CMC).

 
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Cardiomyocytes are the contracting cells which allow the heart to pump. Each cardiomyocyte needs to contract in coordination with its neighboring cells to efficiently pump blood from the heart, and if this coordination breaks down then the heart may not pump at all.

Fibroblast cells give support to the muscle tissue. They are unable to provide forceful contractions like cardiomyocytes, but instead are largely responsible for creating and maintaining the extracellular matrix which forms the mortar in which cardiomyocyte bricks are embedded. Fibroblasts also play a crucial role in responding to injury by creating collagen while gently contracting to pull the edges of the injured area together.

In previous academic studies, tests of pure populations of cardiomyoctes have failed to stay viable making it difficult to study the heart in a lab setting. In their recent paper, the team at George Washington University set out to determine how 3D bioprinting affects these two types of cells and if there is a way to create viable 3D tissue in the lab by bioprinting both CMCs and CFBs in tandem.

The team studied the effects of temperature, pressure, bioink composition, and UV exposure to determine the best conditions for 3D bioprinting heart muscle.

Through LIVE/DEAD assays, bioluminescence imaging and morphological assessment, they determined that cell survival within a 3D bioprinted CMC-laden GelMA construct was MORE sensitive to extruder pressure and bioink composition than the fibroblast-laden constructs. Also they determined that BOTH cell types were adversely impacted by the UV curing step. And finally they determined that using a mixture of cardiomyocytess and cardiac fibroblasts increased viability of the tissue- showing that CMCs <3 CFBs.

Cheers to the team at GWU! Their research creates an important foundation for future studies of 3D bioprinted heart tissue.

Read their paper here.

Newly Formulated Cell Media Will Change the Way We Study Cancer

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The first synthetic cell culture medium was formulated 60 years ago by an American physician named Harry Eagle. As a pathologist, Dr. Eagle needed a way to keep cells alive longer in a laboratory setting in order to study their growth and behavior. His formula, better known at EMEM (Eagle's minimal essential medium), is composed of a mixture of sugars, vitamins, salts, and amino acids and as its name implies, is the bare minimum of nutrients needed in order to keep cells alive ex-vivo.

Since its creation, Eagle’s medium has become an essential consumable in labs worldwide where it is used by researchers to study animal cells. However, the formulation hasn’t changed much since making its debut in 1959 and recently scientists have begun to wonder if feeding cells the bare minimum of nutrients is skewing the results they are obtaining in lab.

Thinking of EMEM as Gatorade (which it essentially is), you can imagine what would happen if you tried to subsist on a diet of Gatorade alone. Your body wouldn’t behave normally under such harsh conditions so why do we expect your cells to be any different?

In 2012, a researcher by the name of Saverio Tardito set out to create a more relevant cell medium.

“The vast majority of biomedical researchers use cell culture media that were not designed to reproduce the physiological cellular environment but were formulated to enable the continued culture of cells with minimal amounts of nutrients and serum”.

Improving the metabolic fidelity of cancer models with a physiological cell culture medium, Science Advances

His final concoction, called Plasmax, is a mixture of approximately 60 nutrients and metabolites found in the human blood. In their paper, published in Science Advances, Tardito and his colleagues at Cancer Research UK Beatson Institute compared Plasmax with traditional cell culture media and found that cells cultured in Plasmax behaved in a more physiological manner.

By studying Plasmax in conjunction with cancer cells, Tardito and his team concluded that their newly formulated medium can improve the degree to which in-vitro models behave as they would in-vivo and ultimately provide better models for cancer research.

As we enter the renaissance of tissue engineering, we are deepening our understanding of the complex organisms that make up the human body. In order to develop novel drugs, better study disease, and regenerate tissue, it is imperative that we develop more relevant models in the lab that mimic the geometry, environment and diet that cells exist on in the body.

Read the full article here.

Allevi Author: 3D‐Printed Sugar Stents to Aid in Surgery

Microvascular anastomosis (or the method of surgically connecting blood vessels) is a common part of many reconstructive and transplant surgical procedures.

There are multiple methods for connecting two veins together including coupling devices, surgical glue, and surgical suturing but each method has it’s downsides; coupling devices can face rejection from the body, glue can introduce contamination or clotting to the vein, and suturing (the most commonly accepted practice) is a delicate and time consuming procedure.

 
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During the suturing procedure, surgeons are in a race against the clock to quickly connect the veins together to ensure that organs continue to receive proper blood flow. However, blood vessels of differing shapes and sizes can sometimes make this procedure difficult to maneuver in a timely fashion.

 
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In their recent paper titled, “3D‐Printed Sugar‐Based Stents Facilitating Vascular Anastomosis”, researchers at Brigham and Women’s Hospital & The University of Nebraska Lincoln collaborated using an Allevi 2 bioprinter to find a solution to aid in the intricacies surrounding this procedure.

Here, dissolvable sugar‐based stents are 3D printed as an assistive tool for facilitating surgical anastomosis. The non-brittle sugar‐based stent holds the vessels together during the procedure and are dissolved upon the restoration of the blood flow. The incorporation of sodium citrate minimizes the chance of thrombosis, and the dissolution rate of the sugar‐based stent can be tailored between 4 and 8 min.

 
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3D printing is an ideal method for constructing these stents because you are able to quickly design and create custom geometries to fit the patient’s vessels.

The effectiveness of the printed sugar‐based stent was assessed ex vivo and found to be a fast and reliable fabrication method that can be performed in the operating room.

This new method of aiding surgeons is a game-changer as it is dissolvable, tunable, and completely customizable. In the future, your doctor could quickly print out stents to match your exact vein geometry which would reduce the time spent on the operating table and under anesthesia.

Interested in learning more about this novel technique? You can read the full paper here: https://onlinelibrary.wiley.com/doi/abs/10.1002/adhm.201800702?af=R&

Allevi Author: Lattices vs Sheets for Cardiac Tissue Bioprinting

There are so many variables that go into creating viable 3d bioprinted tissues; bioink selection, print geometry, cure times, rigidity, flexibility, degradation time and cell viability to name a few. Not to mention, each of these parameters needs to be analyzed and perfected for every cell line in the body. As a community, we are still figuring out the perfect protocol for each organ system.

In a new paper out this week titled “A Comparative Study of a 3D Bioprinted Gelatin-Based Lattice and Rectangular-Sheet Structures”, our newest Allevi Authors tackled one of these lingering questions, “What is the best print structure for cardiac tissue, lattice or sheet?”

Researchers at University of Texas El Paso and University of Texas at Austin used their Allevi 2 bioprinter and furfuryl gelatin to study and compare 3d bioprinted lattices vs sheets. Through their comparison, they discovered that the lattice structure was more porous with enhanced rheological properties and exhibited a lower degradation rate compared to the rectangular-sheet.

Further, the lattice allowed cells to proliferate to a greater extent compared to the rectangular-sheet. All of these results collectively affirmed that the lattice poses as a superior scaffold design for tissue engineering applications.

Read the full paper here to learn more about the rigorous testing and analysis the team conducted during their study.

Allevi Bioprinting in Space

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The physical exploration of space began in the 1950s with the race between the Soviet Union and the United States for who could take those weightless first steps.  Orbiting above earth, astronauts have since made countless discoveries of the galaxy we live in and the science of the stars. On top of the celestial research, space exploration has yielded humanity practical tools that improve our daily lives, such as the GPS in your car, the ear thermometer in your medicine cabinet, and the joystick on your gaming console. Without the constraints of gravity, astronauts are able to study and innovate in a truly novel way.

As we continue to explore deeper into space, astronauts are spending more time in orbit than ever before and need tools that are adaptable and customizable for any given task. This is the ethos behind Made in Space, an organization that focuses on increasing human capability in orbit by bringing 3d printing technology onto the International Space Station (ISS). Accessibility to 3D printing on the ISS has allowed astronauts to print custom plastic tools and parts that are needed to successfully achieve their mission. No need to come back to earth to fetch that tool, you can now print it at zero g.

Here at Allevi, we are driven by the goal of being able to 3D bioprint replacement organs for humans. While we continue to understand the capabilities and constraints of 3d biofabrication here on Earth, the ability to explore cellular function in space could afford us novel discoveries of organ form and function that have never before been studied.

Allevi zeroG bioprinting in space on ISS

In pursuit of this novel research, we have partnered with Made in Space to develop the first bioprinter in space; the Allevi ZeroG. We have designed a compatible extruder that can be outfitted onto Made In Space’s existing Additive Manufacturing Facility on the ISS. The ZeroG bio-extruder will allow scientists on the Allevi platform to simultaneously run experiments both on the ground and in space to observe biological differences that occur with and without gravity.

We are excited to continue to revolutionize how we study biology, not only on the ground but now in space. And perhaps one day, the Allevi ZeroG will aid astronauts in 3D bioprinting replacement organs for deep space travel. We’re excited to participate in this next generation space race.

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