While fully 3D printed hearts are not a reality yet for the roughly 4,000 people in the US waiting for a transplant each year, 3D printing human tissue for regeneration and repair is a big step in the right direction.
The innovative researchers from Carnegie Mellon University (CMU) have long been working with 3D bioprinting to fabricate tissue, and a team from the university’s Materials Science and Engineering (MSE) and Biomedical Engineering (BME) departments recently developed their own low-cost 3D bioprinter, publishing the designs as open source so anyone can build it.
The researchers went the DIY route by using 3D printing to modify a standard desktop 3D printer.
“Essentially, we’ve developed a bioprinter that you can build for under $500, that I would argue is at least on par with many that cost far more money. Most 3-D bioprinters start between $10K and $20K,” explained MSE and BME Associate Professor Adam Feinberg, who’s also a member of the university’s Bioengineered Organs Initiative. “This is significantly cheaper, and we provide very detailed instructional videos. It’s really about democratizing technology and trying to get it into more people’s hands.”
Commercial 3D bioprinters on the market cost up to $200,000+, and are typically also proprietary, closed source machines that can be hard to modify. But the CMU researchers have created a syringe-based, large volume extruder (LVE) that can be used to modify any FFF-style 3D printer.
“What we’ve created is a large volume syringe pump extruder that works with almost any open source fused deposition modeling (FDM) printer,” said Kira Pusch, a recent graduate of the MSE undergrad program. “This means that it’s an inexpensive and relatively easy adaptation for people who use 3-D printers.”
Pusch, BME postdoctoral fellow Thomas J. ‘TJ’ Hinton, and Feinberg recently published a paper, titled “Large volume syringe pump extruder for desktop 3D printers,” in the HardwareX journal, which provides a complete set of instructions, from CAD and STL files to the types of tools needed, for 3D printing and installing the LVE on a typical commercial 3D printer. For the purposes of their work, the CMU team modified a PrintrBot Simple Metal 3D printer.
The abstract reads, “Syringe pump extruders are required for a wide range of 3D printing applications, including bioprinting, embedded printing, and food printing. However, the mass of the syringe becomes a major challenge for most printing platforms, requiring compromises in speed, resolution and/or volume. To address these issues, we have designed a syringe pump large volume extruder (LVE) that is compatible with low-cost, open source 3D printers, and herein demonstrate its performance on a PrintrBot Simple Metal. Key aspects of the LVE include: (1) it is open source and compatible with open source hardware and software, making it inexpensive and widely accessible to the 3D printing community, (2) it utilizes a standard 60 mL syringe as its ink reservoir, effectively increasing print volume of the average bioprinter, (3) it is capable of retraction and high speed movements, and (4) it can print fluids using nozzle diameters as small as 100 μm, enabling the printing of complex shapes/objects when used in conjunction with the freeform reversible embedding of suspended hydrogels (FRESH) 3D printing method. Printing performance of the LVE is demonstrated by utilizing alginate as a model biomaterial ink to fabricate parametric CAD models and standard calibration objects.”
The team demonstrates its system in the paper using common alginate biomaterial and the Freeform Reversible Embedding of Suspended Hydrogels (FRESH) technique, which is signature to Feinberg’s lab.
“Bioprinting has historically been limited in volume, so essentially the goal is to just scale up the process without sacrificing detail and quality of the print,” Pusch explained.
Pusch, the first author of the paper, spent three years as an undergraduate research assistant in the lab, which has a goal of producing open source biomedical research that other researchers can take and expand upon. This accessible research will hopefully help innovation spread, in order to, as CMU put it, “encourage the rapid development of biomedical technologies to save lives.”
Feinberg said, “We envision this as being the first of many technologies that we push into the open source environment to drive the field forward. It’s something we really believe in.”
In addition to the innovative LVE, several other 3D printed parts were also used to modify the Printrbot into a 3D bioprinter. While the LVE helps lower costs, it also gives users the chance to 3D print artificial human tissue at a higher resolution and on a large scale. This could then make way for experimentation with 3D printing biomaterials and fluids.
“Usually there’s a trade-off, because when the systems dispense smaller amounts of material, we have more control and can print small items with high resolution, but as systems get bigger, various challenges arise,” Feinberg said. “The LVE 3-D bioprinter allows us to print much larger tissue scaffolds, at the scale of an entire human heart, with high quality.”
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