Researchers have demonstrated how 3D-printed hydrogels loaded with stem cells can produce superior craniofacial bone grafts that are tailored to an individuals bone structure.
Researchers from Texas A&M University (TX, USA) have brought together the fields of 3D printing, biomaterial engineering and stem cell biology to develop a novel technique to produce personalized craniofacial bone grafts.
Materials used for craniofacial bone implants are either biologically inactive and extremely hard, like titanium, or biologically active and too soft, like biopolymers,” explained co-author Roland Kaunas (Texas A&M University).
In our study, we have developed a synthetic polymer that is both bioactive and mechanically strong. These materials are also 3D printable, allowing custom-shaped craniofacial implants to be made that are both aesthetically pleasing and functional,” Kaunas continued.
Described in a recent study, published in Advanced Healthcare Materials, the new technique involves loading hydrogels with bone stem cells and 3D-printing them to any desired shape. In this way, once the personalized bone grafts are implanted in the target site, they are able to stimulate bone regeneration in a customized shape.
Whilst the pliability of hydrogels is imperative to this technique, their softness can also compromise the accuracy and mechanical integrity of the implant. To overcome this, the researchers developed a nanoengineered ionic-covalent entanglement (NICE) bioink for the scaffolds made from three ingredients, the chemical bonds between which increased the materials strength eight-fold.
The technique the researchers used involved 3D printing parts with the NICE bioink and loading these parts with adult stem cells, which are then chemically induced to convert into bone cells. After a few weeks, the researchers observed an increase in bone cells and consequently an increase in bone-associated proteins and minerals.
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These products then formed an extracellular matrix to facilitate the growth and survival of bone cells. Once the extracellular matrix is fully developed the bone cells can be removed and the hydrogel placed at the site of injury. Healthy bones will encourage healing and, after time, the hydrogel with biodegrade, leaving behind a healed bone in the right shape.
The idea is to have the body’s own bone repair machinery participate in the repair process. Our biomaterial is enriched with this regenerative extracellular matrix, providing a fertile environment to naturally trigger bone and tissue restoration,” Kaunas remarked.
The technique investigated by the researchers provides a strong framework for producing personalized bone grafts that enable in situ bone regeneration. Although this study focused on repairing craniofacial bones, the researchers stressed that they intend to expand the use of the technology to other injuries in the near future.
Sources: Sears C, Mondragon E, Richards ZI et al. Conditioning of 3D printed nanoengineered ionic–covalent entanglement scaffolds with iPhMSCs derived matrix. Adv. Healthc. Mater. doi:10.1002/adhm.201901580 (2020) (Epub ahead of print); https://today.tamu.edu/2020/06/02/texas-am-researchers-use-3d-printed-biomaterials-laced-with-stem-cells-to-create-superior-bone-grafts/