BiofabricationBioprintingMedical AM

X-Pure gelatins for greater consistency in bioprinting

Rousselot’s purified X-Pure gelatin products are expanding the possibilities for bioprinting and tissue engineering

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In the human body, tissues are made up of cells supported by an extracellular matrix (ECM), which itself consists of collagens. These collagens have several functions, not only supporting cells but also offering tensile strength and promoting cell adhesion regulation, chemotaxis, cell migration and direct tissue development. When it comes to bioprinting cells, a structure is needed to support cells and mimic the role of collagens in the body. Gelatin—an organic ingredient derived from collagen hydrolysis—has proven to be a viable option, unlocking opportunities in tissue engineering and bioprinting.

Rousselot, a leader in collagen-based solutions, has developed a range of gelatin-based products, including X-Pure modified gelatins, that can be used to promote cell growth in tissue engineering and bioprinting applications. Specifically, these X-Pure gelatins can be used to form thermo-reversible hydrogels that can be printed as a scaffold or cell carrier to encourage cell seeding, or can be used as a coating to improve the cell support of another biomaterial carrier.

From gelatin to GelMA

Before diving into the benefits of Rousselot’s X-Pure gelatin products, it’s first important to understand GelMA, a gelatin methacrylate biomaterial that is today among the most commonly used biomaterials for regenerative bioprinting applications. GelMA was developed just over two decades ago at the University of Ghent by Dr. An Van Den Bulcke, and offers excellent biocompatibility, tunable biodegradability and the ability to be crosslinked.

The material was developed as an alternative to pure gelatin, which—while excellent for cell growth—has a specific challenge associated with it: it melts when exposed to temperatures in the range of 31.7–34.2 °C. This of course poses challenges since cells thrive at body temperature (37°C). The addition of methacrylate anhydride to gelatin results in a more stable material, since the ability to crosslink makes it possible to increase the biomaterial’s stability at body temperature.

However, because GelMA can be made and synthesized in labs all over the world, it is often plagued by batch-to-batch inconsistencies. Additionally, GelMA can be prone to impurities, like endotoxins or residual methacrylic acid, which can influence research results and actually cause issues in vivo, such as tissue inflammation, allergen sensitivity and, in worst cases, fatal shock.

X-Pure gelatins for greater consistency in bioprinting. Rousselot’s purified X-Pure gelatin products are expanding the possibilities.

X-Pure GelMA

To address these inconsistencies and establish greater reliability (and safety) for the versatile biomaterial, Rousselot developed X-Pure GelMA, a modified gelatin methacrylate. The product is the world’s first gelatin methacryloyl made under GMP conditions and offers ultra-low impurity levels, batch-to-batch consistency and tunable mechanical properties. This combination of characteristics means that X-Pure GelMA can be suitable for a wide range of biomedical applications like regenerative medicine and tissue engineering.

For bioprinting users, Rousselot’s X-Pure GelMA offers the consistency that cells need to thrive. It also streamlines the bioprinting process altogether by ensuring that researchers go into their work knowing the exact properties of the biomaterial. That is, while regular GelMA requires researchers to finely tune and optimize bioprinter settings with each new batch (a setup that can take weeks), the same settings can be used for a specific variation of X-Pure GelMA, regardless of the batch number.

X-Pure GelMA’s physicochemical properties can also be tuned through crosslinking for different applications. Rousselot says: “GelMA can be synthesized with a specific degree of functionalization (DoM) and molecular weight (MW) enabling tunable hydrogel formation”. This means that it can be adapted for both high and low viscosity bioinks. The final stiffness of the hydrogel after crosslinking is controlled through material properties, formulation of the bioink and printing conditions such as crosslinking temperature. The consistency of X-Pure GelMA means that the stiffness of the hydrogel can be predicted based on the selected ink formulation and printing conditions. This is in contrast to lab-made GelMA, where each batch requires trial and error experiments to figure out how to recreate the desired hydrogel stiffness.

X-Pure gelatins for greater consistency in bioprinting. Rousselot’s purified X-Pure gelatin products are expanding the possibilities.

X-Pure GelDAT

In 2021, Rousselot introduced another purified, modified gelatin product suitable for bioprinting applications: X-Pure GelDAT. This biomaterial, an ultrapurified gelatin desaminotyrosine, combines the purity of GelMA with superior adhesion to human tissues. This, Rousselot says, can “increase the range of in-body applications reaching the clinic.” X-Pure GelDAT, like X-Pure GelMA, can also be combined with additional biomaterials in the production of complex structures for applications like drug delivery, tissue engineering, organ-on-a-chip and wound dressing.

At the time of the material’s release, Dr. Jeff Daelman, Business Development Manager at Rousselot Biomedical, commented on the product’s ability to accelerate the advancement of research to clinic: “Rousselot’s X-Pure GelDAT’s research grade is functionally equivalent to the GMP-grade material, so researchers have less risk of having to re-validate their biomaterial prior to clinical trials. Compromising on quality in early research can also cause significant scale-up issues and delays in preparation for clinical trials. X-Pure GelDAT can be used throughout every development phase.”

X-Pure GelDAT is, like X-Pure GelMA, available in a range of molecular weights and can be tailored to specific needs of different types of cells. In other words, the physicochemical properties of X-Pure gelatins can be tuned for different degrees of stiffness in order to mimic the stiffness of different types of human tissue. Hydrogels based on gelatin can be as stiff as 200 kPa or as soft 500 Pa or lower. Thus, an environment can be created that recapitulates the stiffness of tissues as soft as brain tissue and as hard as precalcified bone (and everything in between).

X-Pure gelatins for greater consistency in bioprinting. Rousselot’s purified X-Pure gelatin products are expanding the possibilities.

Case study: In-situ bioprinting

Rousselot’s X-Pure GelDAT biomaterial is playing a key role in an innovative research project that is developing a bioprinter that can print living constructs directly in the body to repair damaged tissues. This bioprinter is a world apart from the desktop machines we are accustomed to seeing, and uses muscle-like soft robots to extrude biomaterial structures directly onto tissues.

The research project, out of the University of New South Wales in Sydney, Australia, has the potential to be used for in-situ 3D bioprinting and endoscopic surgery and could help overcome existing challenges with traditional bioprinting, like surface mismatching and tissue damage or contamination caused in the transport of bioprinted tissues ahead of implantation.

The bioprinting solution relies on soft artificial muscles to control a print head, which is controlled by a machine learning tool for the most precise movements. In the study, Rousselot’s X-Pure GelDAT was among the biomaterials used in the printing of an artificial colon and repairing tissue on a pig kidney. GelDAT was regarded as ideal not only for its biocompatibility, but also due to its  exceptional adhesive properties and ability to crosslink with tissues.

“We chose to use GelDAT in this work due to its ease of extrusion and photopolymerization, making it an excellent bioink platform to test this new device,” said Dr. Jelena Rnjak-Kovacina, Scientia Associate Professor and ARC Future Fellow at the Graduate School of Biomedical Engineering. So far, the results of the work are promising: cells suspended in the GelDAT biomaterial survived printing tests, and the researchers are hopeful their technology can improve tissue restoration down the line.

Ultimately, Rousselot’s X-Pure gelatin biomaterials are a key ingredient in bioprinting, offering the consistency, purity and tunability that scientists need to develop and construct environments for cells to thrive.

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Tess Boissonneault

Tess Boissonneault is a Montreal-based content writer and editor with five years of experience covering the additive manufacturing world. She has a particular interest in amplifying the voices of women working within the industry and is an avid follower of the ever-evolving AM sector. Tess holds a master's degree in Media Studies from the University of Amsterdam.

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