Allevi Authors

Allevi Author: 3D Bioprinting a Spinal Cord

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People often ask us, “what is it that a bioprinter can do really well?”, and we tell them that it’s the ability to print and pattern living cells. Your cells are incredible organisms; they understand the environment around them and communicate with other cells to perform specific organ functions. This is why a bioprinter is such an amazing tool - it empowers you to control the geometry and placement of multiple cell types which allows cells to mimic the environments that they are used to in the body. But some cells are more finicky than others… induced pluripotent stem cells and neural cells for instance are difficult to keep alive and difficult to control.

That’s why this next #AlleviAuthor from University of Minnesota really blew us away with their new paper titled “3D Printed Stem-Cell Derived Neural Progenitors Generate Spinal Cord Scaffolds” and published in Advanced Functional Materials, wherein they used Allevi bioinks to 3D bioprint a spinal cord using induced pluripotent stem cells and oligodendrocyte progenitor cells (OPCs).

Successfully bioprinting multicellular neural tissue is a huge win for the field of regenerative medicine as it would allow damaged tissue to rebuild functional axonal connections across the central nervous system, essentially healing damaged connections. This technique will hopefully help develop new clinical approaches to treat neurological disease, such as spinal cord injury.

You can access the full paper here to learn more.

Allevi Author: Plant Based Hydrogels for Cell Laden Bioprinting

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Time for another inductee to the #AlleviAuthor club. Researchers from University of California, Berkeley and IBM used their Allevi 2 bioprinter to study the printability and viability of plant based bioinks.

In their paper titled, “Agarose-Based Hydrogels as Suitable Bioprinting Materials for Tissue Engineering” and published in ACS Biomaterials Science & Engineering, they compared agarose-based hydrogels commonly used for cartilage tissue engineering to Pluronic. The goal is to find a bioink that has great printability without sacrificing cell viability.

The team compared mechanical and rheological properties, including yield stress, storage modulus, and shear thinning, as well as construct shape fidelity to assess their potential as a bioink for cell-based tissue engineering. Read on to find out which ratios of alginate and agarose demonstrated the best cell viability as well as print structure for their cartilage tissue engineering needs: https://cdn-pubs.acs.org/doi/10.1021/acsbiomaterials.8b00903.

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 Author: Review of Bone Biofabrication Methods & Bioinks

In the USA alone, 500,000 bone grafting procedures are performed annually, with musculoskeletal-related disabilities costing about $240 billion each year. In spite of the advancements over the past 20 years, scientists and engineers have been unable to provide a material that fulfills every characteristic needed for bone tissue to be physiologically relevant in clinical applications.

In this edition of the #AlleviAuthor series, our very own Director of Bioengineering, Taci Pereira, reviews state of the art bone tissue biofabrication technologies for the Journal of 3D Printing in Medicine.

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Pereira examines the six essential characteristics of bone graft materials; osteoinduction, osteoconduction, osteointegration, biocompatibility, translatability, and growth factor necessity.  

In addition to reviewing bioinks for bone engineering, Pereira examines the different techniques that have emerged within the biofabrication field; 3D bioprinting, selective laser sintering (SLS), electrospinning and stereolithography.

Read on below to learn about the promising methods for bone engineering, where Pereira sees a need for innovation and why she is excited for the future of Hyperelastic Bone.

State of the art biofabrication technologies and materials for bone tissue engineering

 

Allevi Author: UPenn bioprints custom nasal defects

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We're proud to bring you yet another #AlleviAuthor - this one from down the street at University of Pennsylvania.  Dr. Chamith Rajapakse's Lab at UPenn focuses on the development and application of image guided 3D bioprinting for personalized clinical applications.

In his most recent publication, Dr. Rajapakse bioprinted a scaffold that precisely matched a patient’s nasal septal defect, in both size and shape using the Allevi 2 bioprinter. This serves as the first step in a major goal to create patient-specific tissue engineered grafts for NSP repair and beyond.

Here at Allevi, we envision a future of truly personalized medicine. The research by Dr. Rajapakse and his lab brings this future that much closer within the bone, cartilage and muscle tissue types.  One can being to imagine the future of being able to reconstruct cleft palates, nasal septal perforations, broken bones, torn ligaments, vertebrae and so much more.

Read on for the abstract and check out the full publication here.

Abstract: Nasal septal perforations (NSPs) are relatively common. They can be problematic for both patients and head and neck reconstructive surgeons who attempt to repair them. Often, this repair is made using an interpositional graft sandwiched between bilateral mucoperichondrial advancement flaps. The ideal graft is nasal septal cartilage. However, many patients with NSP lack sufficient septal cartilage to harvest. Harvesting other sources of autologous cartilage grafts, such as auricular cartilage, adds morbidity to the surgical case and results in a graft that lacks the ideal qualities required to repair the nasal septum. Tissue engineering has allowed for new reconstructive protocols to be developed. Currently, the authors are unaware of any new literature that looks to improve repair of NSP using custom tissue-engineered cartilage grafts. The first step of this process involves developing a protocol to print the graft from a patient's pre-operative CT.

In this study, CT scans were converted into STereoLithography (STL) file format. The subsequent STL files were transformed into 3D printable G-Code using the Slic3r software. This allowed us to customize the parameters of our print and we were able to choose a layer thickness of 0.1mm.  A desktop 3D bioprinter (Allevi 2) was then used to construct the scaffold.

This method resulted in the production of a PCL scaffold that precisely matched the patient’s nasal septal defect, in both size and shape. This serves as the first step in our goal to create patient-specific tissue engineered nasal septal cartilage grafts for NSP repair.