A recent Australian study outlines how a new type of hybrid material may allow bone replacements to be printed directly inside a patient’s body in a dramatic step toward solving many issues with current bone replacement techniques. This process includes the ability to print bone using live cells and without the use of harsh chemicals, both of which are staples of current methods.
Detailed in a research paper published in the journal Advanced Functional Materials, by study co-authors Dr. Iman Roohani, a bioengineer from the University of New South Wales (UNSW) School of Medicine, and Dr. Kristopher Kilian, from UNSW’s School of Chemistry, their process used an off-the-shelf 3D printer, along with their custom-designed “ink.”
Background: Bone Replacement Procedures
At present, the best, most proven method for bone replacement is an autologous graft, where a section of the patient’s own bone is taken from another part of the body and grafted onto the site where the new bone is needed. Unfortunately, this method still has high rates of rejection and a limit to the amount of bone that can be harvested in the first place.
Various attempts to synthesize a suitable replacement have been tried, including using hydrogels, thermoplastics, or even bio-ceramic “hyper-elastic” pseudo-bones. Still, like autologous grafts, all have met several hurdles. That’s primarily due to the unique combination of living and dead tissue that makes up the typical human bone.
“Bone is a highly mineralized tissue which forms at ambient conditions by continuous crystallization of the mineral phase within an organic matrix in the presence of bone residing cells,” explains their research paper, before concluding that, “despite recent advances in the biofabrication of complex engineered tissues, replication of the heterogeneity of bone microenvironments has been a major challenge in constructing biomimetic bone scaffolds.”
The process these researchers have pioneered, they say, is different.
“In contrast https://thedebrief.org/with-the-help-of-a-dead-insect-israeli-reseato previous materials, our technique offers a way to print constructs in situ which mimic the structure and chemistry of the bone,” said Dr. Roohani in an interview with IEEE Spectrum. “The opportunities are limitless.”
Analysis: Printing Bones With A 3D Printer
To meet this daunting list of challenges, the UNSW team spent two years perfecting a biocompatible calcium phosphate material, meaning it wouldn’t present a risk of rejection by the host and one that also forms a malleable paste at room temperature.
That material is then placed in a gelatin bath or other aqueous environment to simulate the inside of a human body, causing a chemical reaction to occur, which hardens the paste into a porous matrix or nanocrystals much like the actual bone it is replacing.
“It’s really the first example of integrating ceramic materials that emulate many aspects of native bone with live cells,” says fellow project researcher Kris Kilian in a short video highlighting the technique. “This really opens up the opportunity where you may be able to actually directly print a patient’s bone within a cavity.”
Kilian explains the technique’s advantage further, describing how, “during surgery, if they [the patient] have a bone resected for disease, or have a tumor taken out, then we can actually take scans of that bone, and then put that onto [sic] the 3D printer, and then directly print, within a cavity of a patient, with their own cells being there. And those cells may be able to then graft, and form native bone naturally.”
In that same video, Dr. Kilian sums up the advantages this process offers, all ideally leading to “quicker surgery times, a reduction in suffering, and also hopefully [saving] lots of lives.”
Outlook: The Future of Bones and 3D Printers
The research team’s exact method is still undergoing refinements, but they performed their successful tests with an off-the-shelf 3D printer, specifically the Hyrel 3D Engine HR. They did, however, equip the device with a custom nozzle.
Dubbed ‘COBICS’ for Ceramic Omnidirectional Bioprinting in Cell-Suspensions, Dr. Roohani says that in the future, their process can also be adapted to work on other types of 3D printers including portable and handheld types that can be used directly in the surgical theater. “You’ll need to engineer the printer for each application,” he explained in the IEE Spectrum post, “but the concept and the principle of the technique will be similar.”
Moving forward, the team is now in the process of designing a bath that will let them print even larger replacement bone samples. They are reportedly undergoing small animal tests to see how it stacks up against traditional bone grafts. After that, they are reportedly hoping to work with dentists, surgeons, and other healthcare professionals to look into specific applications and possibly even partner with them to seek FDA approval, which is something the regulatory agency has already indicated they would be willing to consider.
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