3D printing accelerates tissue engineering research

Conventional surgical treatments for cardiovascular disease rely on autografts. This involves harvesting a blood vessel from a less vital part of the patient’s body and using this to repair or bypass a more important damaged or blocked vessel. However, the availability of autografts is limited and obtaining them requires invasive surgery. Synthetic vascular grafts made from polymer materials are also available, although these are prone to infection and blood clotting, especially in smaller diameter vessels. This is where tissue engineering fits in, enabling new blood vessels to be grown in the lab and then used for implantation.

3D printing innovation

Dr Sam Pashneh-Tala from the University of Sheffield uses high-precision desktop stereolithography (SLA) 3D printing to enable the production of tissue-engineered blood vessels with a variety of geometries. His unique methods will allow for patient-specific vascular graft designs to be produced, enabling improved surgical options. The technology also provides a unique testing platform for new vascular medical devices for those suffering from cardiovascular disease - which is currently the number one cause of death worldwide. 

Dr Pashneh-Tala uses scaffold-based tissue engineering to produce his blood vessels. Cells are grown over a scaffold that is in the shape of the required vessel. The scaffold guides and supports the growth of the cells and is produced from a material developed by Dr Pashneh-Tala. 3D printing is used to produce moulds which are used to manufacture the scaffold in the required vascular geometries.

To manufacture the mould, Dr Pashneh-Tala designed the blood vessel mould with Solidworks CAD software, and then 3D prints the desired shape with his Formlabs SLA printer. The moulds are then assembled and secured on top of each other in a sandwich-like formation with a cavity around the core. Once secured, the cavity is filled with the custom biodegradable polymer emulsion, which was developed at The University of Sheffield by Dr-Pashneh-Tala and his team. When the polymer sets, the researcher is left with a porous scaffold with microscopic holes that the cells are able to grow into. Over time the structure will dissolve, leaving just the cells in the desired shape.

Once the tissue engineering scaffold has been seeded with cells, it must be cultured in the lab in order to mature into the required tissue. This process is performed inside a bioreactor, a chamber that contains the developing tissue and can reproduce the internal environment of the body. Rather than having to outsource the manufacturing of these chambers, Dr Pashneh-Tala uses his Form 2 stereolithography (SLA) printer to prototype these in-house. By doing this, he can quickly iterate the designs based on the tissue culture he is creating and print the design in his lab in a matter of hours, saving costs and weeks in development time.

Cheaper by design

“Previously I would have paid between £270-£300 to outsource a polycarbonate chamber,” commented Dr Pashneh-Tala. “With my Formlabs printer, I am able to print the design in my lab using Dental SG, a biocompatible and autoclavable material, for £30-£40. The chamber is then easily sterilised and ready to be used straight away.”

“Regenerative medicine and bioprinting functional tissue substitutes have numerous benefits, from minimising immune rejection to reducing the need for animal and even human samples,” said Gaurav Manchanda, Director of Healthcare at Formlabs. “However, the cost of development for such intricate and technically challenging devices is not always aligned with the budgets available to researchers and teaching hospitals, even in the UK.

“By using Formlabs printers and scaffold-based engineering techniques, Dr Pashneh-Tala has proven that 3D printing can be an accessible and revolutionary technology in the creation of tissue constructs with precise biomimetic properties. It’s extremely exciting and humbling to play a part in democratising the technology used to assist medical researchers in their work to help patients and populations with life threatening conditions.”