An improved bioprinter capable of printing human-scale, structurally stable tissues in any shape is reported online this week in Nature Biotechnology. Although more research and development are needed before tissues produced by this printer might be suitable for transplantation into patients, the new system overcomes several technical obstacles to achieving this goal.
3D bioprinters are machines that print cells in layered patterns with the aim of creating a functional tissue or organ. However, the resulting constructs are often structurally unstable and too fragile for surgical implantation. Moreover, because they lack blood vessels, their size is constrained by the diffusion limit for nutrients and oxygen, which is around 200 micrometers-too small to make most human tissues and organs.
Anthony Atala and colleagues addressed the problem of structural stability by printing cells together with biodegradable polymer materials that confer mechanical strength until the newly forming tissue matures. To overcome the size limit and produce large tissues, they integrated microchannels into the construct design so that nutrients and oxygen can be delivered to cells anywhere in the structure.
The authors also demonstrate an approach for customizing the shape of printed constructs to the needs of individual patients. They use clinical imaging to create a 3D computer model of the missing tissue, and translate the model into a program that guides the printer nozzles that dispense cells.
The study explores the capabilities of the new bioprinter for fabricating bone, cartilage and skeletal muscle using human, rabbit, rat and mouse cells. Future refinements that will be required to make transplantable tissues include the use of clinical-grade human cells (ideally derived from the patient) and a wider variety of cell types printed in patterns that replicate native tissues.