Researchers at Texas A&M University have developed a 3D-printable hydrogel bioink containing mineral nanoparticles that can deliver protein therapeutics to control cell behavior. The material does not provoke the immune system and the researchers hope that it could be useful in replacing damaged tissues for regenerative medicine.
3D printing is a promising method for creating cellular constructs with specific shapes and morphologies. These can function as implants that would allow damaged or missing tissues to regenerate. However, 3D printing structures containing delicate cells, or molecules that can control cellular behavior, such as growth factor proteins, is challenging. This requires researchers to balance the physiological needs and sensitivity of biological materials with the physical constraints of a 3D printing system.
Printed constructs also need to be suitable for implantation, meaning that they need to have the correct mechanical properties and shouldn’t provoke the immune system after implantation. These challenges inspired this group of Texas A&M researchers to develop a new bioink for 3D printed constructs.
The bioink contains polyethylene glycol (PEG), a polymer component that is non-immunogenic, and so is highly suited for implantable materials. However, PEG is typically not applicable to 3D printing, as it is not viscous enough when in solution. The researchers solved this by combining PEG with mineral nanoparticles, called nanoclay, which made the resulting mixture more printable. The bioink is injectable and it quickly stops flowing and cures in place once in position. These properties make it highly suited for 3D printing.
The resulting structures allowed cells to grow within them. The nanoclay also has another benefit in the constructs – it allows for proteins, such as growth factors, to be incorporated in the structures for long-term protein therapy. “This formulation using nanoclay sequesters the therapeutic of interest for increased cell activity and proliferation,” said Charles W. Peak, a researcher involved in the study. “In addition, the prolonged delivery of the bioactive therapeutic could improve cell migration within 3D printed scaffolds and can help in rapid vascularization of scaffolds.”
In the future, researchers may be able to print new tissues and organs for regenerative medicine. Identifying the optimal materials to achieve this is an important stepping stone towards this goal.