heart valves

3D Bioprinting Replacement Heart Valves

allevi advanced biomatrix collagen aortic pulmonary heart valve bioprint 3d bioprinted

Throwing it back today to show you this heart valve that was 3d bioprinted using the Allevi 2 with collagen from Advanced BioMatrix.

Your heart has four valves (one for each chamber) that are made up of thin flaps of tissue called cusps. These flaps open and close to allow blood to move through the heart while beating.  The cusps attach to an outer ring of tougher tissue called the annulus. The annulus helps the valve maintain proper shape under the normal strains and stresses of a heartbeat. 

 
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It is essential that your valves open and close tightly to ensure proper blood flow through the heart and onto the rest of your body. A diseased or damaged valve can give you an irregular heartbeat and eventually lead to heart failure. More than 5 million Americans are diagnosed with heart valve disease every year.

 
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Many people can live with valve disease and do not require surgery. However, in some cases, the valve needs to be fixed or replaced. Current methods for replacing a damaged valve included plastic parts or animal tissues.

Allevi users are working towards a future where your #doctor is able to 3d bioprint a custom replacement valve from your own heart cells to reduce the rate of failure and rejection. 3D bioprinting is an amazing design tool that allows you to print custom geometries and tune the rheological properties to provide your cells with the support structure they need to do their job. Just another amazing way our users are changing the future of medicine. #buildwithlife #healwithlife

Allevi Author - Valentine's Edition: 3D Bioprinting Aortic and Cardiac Scaffolds

Allevi bioprinter bioprint aortic and cardiac scaffolds

On this very special Valentine's Day edition of #AlleviAuthor, we'd like to introduce our newest member of the #alleviauthor club whose work studies bioprinting to repair broken heart...valves. Benjamin Stewart, whose thesis was recently presented to the the faculty of the Daniel Felix Ritchie School of Engineering and Computer Science at the University of Denver, studies cardiac tissue specifically for aortic valve repair. 

Stewart's work focuses on 3D bioprinting hydrogels for tissue engineered ascending aorta scaffolds using the AlleviBeta 3D bioprinter. Biocompatible polymers were tested for extrusion mechanics, mechanical and fluid properties, crosslinking dynamics, and degradation properties. Mechanical stretch properties and dynamic performance were tested extensively.

One of the most important aspects of 3D bioprinting is finding the correct biocompatible materials that mimic the mechanical properties of the tissues in your body. Stewart's extensive materials research lays the groundwork for future bioink development for cardiac clinical applications. With the correct bioink, doctors could one day print replacement parts that mechanically perform just like the healthy cardiac tissue in your body. Read on to learn more.

ABSTRACT: The gold standard in 2016 for thoracic aortic grafts is Dacron®, polyethylene terephthalate, due to the durability over time, the low immune response elicited and the propensity for endothelialization of the graft lumen over time. These synthetic grafts provide reliable materials that show remarkable long term patency. Despite the acceptable performance of Dacron® grafts, it is noted that autographs still outperform other types of vascular grafts when available due to recognition of the host’s cells and adaptive mechanical properties of a living graft. 3D bioprinting patient-specific scaffolds for tissue engineering brings the benefits of non-degrading synthetic grafts and autologous grafts together by constructing a synthetic scaffold that supports cell infiltration, adhesion, and development in order to promote the cells to build the native extracellular matrix in response to biochemical and physical cues.

Using the Allevi 3D bioprinter, scaffold materials we tested non-Newtonian photosensitive hydrogel that formed a crosslinked matrix under 365 nm UV light with appropriate water content and mechanical properties for cell infiltration and adhesion to the bioprinted scaffold. Viscometry data on the PEGDA-HPMC 15%-2% w/v hydrogel (non-Newtonian behavior) informed CFD simulation of the extrusion system in order to exact the pressure-flow rate relationship for every hydrogel and geometry combination. Surface tension data and mechanical properties were obtained from material testing and provide content to further characterize each hydrogel and resulting crosslinked scaffold. The goal of this work was to create a basis to build a database of hydrogels with corresponding print settings and resulting mechanical properties.

Read the full thesis here.

10 Cools Things You Could Print with a 3D Bioprinter in the Near Future

3D bioprinting is an intuitive way to approach biology. But not many people realize its versatility. To give an idea of what is possible through 3D bioprinting, we’re starting a little series called “Allevi Applications.” Hopefully, this will make the idea of bioprinting a little more accessible! So without further ado, let’s get started.

1. Joint replacements, think knee, ankle and elbow.

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2. Microfluidic chips

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3. Cell scaffolds for replacement organs, eventually making fulling functioning organs

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4. Cartilage

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5. Accurate surgical models for physicians to practice difficult procedures

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6. Drugs with custom release rates, compositions and geometries

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7. Teeth and dental implants

8. Skin grafts for burn victims

9. Casts and bioactive clothing

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10.  Blood vessels, arteries and heart valves

And our users are just getting started. Check back as we cover new publications from #Allevi Authors and see what amazing applications they come up with next. 

Research Spotlight: Dr. Doris Taylor is Building a Heart from Scratch

Here at Allevi, we’re always keeping an eye out for research being done in tissue engineering and stem cell biology. Together, these disciplines form the backbone of regenerative medicine.

So, it’s only natural that Dr. Doris Taylor’s research at the University of Minnesota and at the Texas Heart Institute caught our eye. Click the image below to check out this brief video describing the premise of her work:

In sum, her approach to creating tissues and organs for transplantation is this: first, wash out the existing cells in a donor’s organ (using a standard detergent called sodium dodecyl sulfate, or SDS) to leave only the extracellular matrix, and then re-cellularize this natural scaffold with the patient’s stem cells. After cell growth and proliferation, the end result is a brand new heart made from the recipient’s own cells. This approach is groundbreaking because it lessens, or nullifies altogether, the problems associated with donor organ rejection.

How could Allevi help out with this goal? Well, we know that an extracellular matrix scaffold is needed to seed the patient’s cells and eventually grow a heart. Why not 3D bioprint such a scaffold, instead of obtaining it by washing out the cells of a animal, or donor’s heart?

Imagine: a patient suffers cardiac trauma and is in need of new heart tissue, or a new heart entirely. A 3D bioprinter could print an extracellular matrix scaffold customized for the patient, and then the patient’s cardiac stem cells would be grown on the matrix. Given the proper incubation, environment, and growth factors, a new, healthy, beating heart could be ready for the patient in a matter of days. This takes the need for a donor out of the transplant equation.

Allevi is looking forward to what Dr. Taylor and her team come up with next. The technique she has developed could be applied to a wide array of organs, and even blood vasculature. The possibilities are endless, and a 3D bioprinter can only help realize the promise of regenerative medicine.

Click here for more information about Dr. Doris Taylor and her work.