Engineering 101

Bioprinters to lead to 3D printed replacement organs

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In the wake of recent developments in the field of cell therapy, bioprinter vendors are seeking to market to more sophisticated researchers. One desktop 3D printer that seeks to serve this market demonstrates the rapid evolution of tissue printing technology. Called the Bio X, from Cellink, the printer comes with three exchangeable print heads, temperature control, integrated UV for sterilization and solidifying tissue matrices, and a touchscreen that works through lab gloves. The self-contained printer has a HEPA filter and fits under a lab hood.

The system is designed to print cells and bioinks, materials that support the cells while they form an extracellular matrix into tissues and organs for drug testing and cell therapy in regenerative medicine.

This particular unit builds on some technologies originally introduced in Cellink’s entry-level Inkredible and Inkredible Plus printers. Those printers were designed primarily for small academic and pharmaceutical labs. Bio X is aimed at researchers who require more precise control or want to build more complex samples, says Eric Gatenholm, CEO of the Swedish firm.

The system comes at the right time. On December 5, the U.S. Food and Drug Administration issued its first guidance for 3D printing devices. Having FDA guidelines makes it easier for companies to submit products for government approval.

FDA developed its guidelines based on its own reviews of more than 100 3D products, ranging from knee and dental implants to time-released medicines, and talks with key players in the industry. FDA cited the technology’s potential, noting that “burn patients in the near future will be treated with their own new skin cells that are 3D printed directly onto their burn wounds.” Further down the road, it expects to see 3D replacement organs.

FDA’s announcement reflects the advanced work researchers are conducting in the lab working with 3D bioprinters. While this particular bioprinter was not designed as a production printer, it does have a 130x90x70mm high build volume. It achieves 1-micrometer resolution on 50-micrometer-thick layers.

The system mounts three snap-in print heads at a time, which users can customize or change. The printer also comes with a pneumatic head that heats to 85°C. An optional pneumatic head goes to 130°C, hot enough to print many thermoplastics for supports, matrices, or devices. A thermoplastic extruder head goes to 250°C and handles a wider range of polymers. The unit also has a heated print bed that broadens the types of bioink the unit can deposit. Another optional pneumatic head chills materials to 4°C for collagen-based and other bioinks that require cooler temperatures.

In addition to pneumatic heads, Cellink offers optional ink jet heads for high-speed printing and piston pump syringe heads for better control of flow rates and deposited volume. There are also two tool heads. The first is a high-definition camera to track the printing process to ensure quality. The second holds a custom laser. Lasers emit UV radiation to solidify tissue matrices. Two integrated lasers are provided at wavelengths (365 and 405nm) that work with the most common chemicals used to initiate those reactions. The custom head enables users to mount a different wavelength laser if they work with other chemicals.

The system also has built-in 275nm UV-C lamps, which can be used after cleaning to run sterilization cycles and kill bacteria within the build space. At the top of the unit sits a HEPA H14 dual filter to remove small particles and microorganisms. Dual fans pull purified air through the filter, down to the build space, and out the sides of the unit to generate clean, positive pressure within the enclosed system.

Cellink came to 3D printing from an unusual background. In 2015, the company began selling bioinks, which provide a temporary or permanent support while cells create their own extracellular matrix. Its bioinks, sourced from local wood cellulose and alginate from seaweed, were the first ones designed to mix with any cell type.

Gatenholm says his firm backed into 3D printers while testing inks, finding there was a market need for smaller features. The first model they created, he says, had two mounted printheads (not heated), achieved 100-micrometer resolutions, and sold for only $10,000. It looked like an early MakerBot. In fact, Gatenholm admits to using the same off-the-shelf, side-mounted stepper motor and rubber belt configuration that MakerBot used to drive its two print head because it is fast and reliable.

“Everyone is talking about 3D tissues, but 99% of research today is still done in a Petri dish,” Gatenholm said. He hopes the lower price tag will make it easier for more labs to own these types of printers. Cellink also emulated MakerBot’s cloud service, Thingaverse, where users share digital design files. Calling their service Bioverse.co, it contains CAD models and protocols for printing 3D tissue and human organs.

Source Alliance of Advanced BioMedical Engineering (AABME)

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