Custom-made bones. This concept, which until recently seemed like science fiction, is becoming more and more achievable thanks to advances and research in tissue engineering and additive manufacturing. Incredible new perspectives are coming to light in this domain thanks to a research team led by professors Isabelle Villemure, Carl-Éric Aubin  (professors at Polytechnique Montréal) and Dr. Marie-Lyne Nault, and first author Mohammad Ali Bagheri. Their research is focused on distraction osteogenesis, a technique of slowly lengthening a fractured bone to allow new osseous tissue to form between the two fragments.

To do this, the team designed scaffolds, structures made of porous materials that support and guide osseous healing by providing a frame in which the cells can grow and regenerate. Optimization of these designs was done with the help of machine learning, using artificial intelligence techniques to improve the models and structures by adjusting the parameters to maximize their effectiveness and performance.

Creating complex structures

One of the key aspects of the team’s research is the use of additive manufacturing, specifically selective laser sintering (SLS), an advanced form of 3D printing. This method involves solidifying layers of technical polymer powder, like nylon (polyamide), to create very porous structures with small details. Additive manufacturing allows the team to create complex geometric structures and explore new designs for biomedical engineering.

Mohammad Ali Bagheri was inspired by a book about complex geometry based on origami: “You can make almost anything out of paper. The challenge was then to be able to recreate the principles of origami in the metamaterial.” This process led him to design the perfect materials. “Origami allows us to create structures with specific mechanical properties, such as deformability and recovery. These designs evolve and can be adjusted to different sizes and properties, making it suitable for a variety of uses in tissue engineering.”

100 times on the job, but just one on the platform!

Bagheri also developed a virtual test platform using Bayesian machine learning. This platform optimizes the designs for different bones before scaffold production. The platform saves time and resources by automatically generating computer-assisted design (CAD) files and virtually testing thousands of designs. This method makes creating predictive models easier.

Potential applications for other tissues

While the primary objective of the work is distraction osteogenesis, this technology could also serve to address other forms of osseous deficits, such as open traumas and infections. the design could eventually be used for repairing tendons and soft tissues. The 3D printed structures can be tested for their biocompatibility and cellular response, making the tests more efficient and precise.

Additionally, by changing the parameters determining cell behaviour, the platform allows one to understand and improve cellular response. This interdisciplinary approach requires the collaboration of diverse experts to explore these avenues to their full potential.

Photo © CHU Sainte-Justine (Véronique Lavoie)