Explaining Bioprinting

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3D printing began to revolutionise industries with digital files providing the blueprint to create products layer by layer as if by magic. A decade ago; Bioprinting took it one step further and began to revolutionise the field of medical research and treatment. Here, we ask Manchester Biogel what this means for the future of medicine.

Printing living materials

Unlike traditional 3D printers, bioprinters are designed to print biological materials (often laden with living cells). These “bioinks” can also be combined with 3D printed cell “scaffolds”, allowing these cells to multiply. In this way, bioprinting can be used with additive manufacturing processes (such as traditional 3D polymer products) to create living biological systems.

Printing the inside out

The scope of bioprinting for medical applications cannot be underestimated. Not only can this cutting-edge technology be used to help repair or replace damaged joints and ligaments, but it can also be used in drug and cancer research due to the ease with which complex medical constructs can be created outside of the body whilst replicating elements of what happens inside.

Structure, form and function

Bioprinting literally “builds” on the existing technology of 3D printing, using CAD software and 3D printers and/or biomaterials to create functional tissues and organs; layer by layer. The ability to culture cells in 3D also enables the mimicry of key tissue characteristics (unlike 2D monolayers), meaning that fibrous structures such as the extracellular matrix can be more easily explored. Cells are organised in specific ways. It has proved highly challenging to try and mimic these structures, whereby bioprinting offers researchers the ability to print items with a hierarchical structure. Exploring the extracellular matrix is vital to help advance in treating aggressive cancers such as pancreatic cancer.

The ability to create and experiment with function and form is critical in biology, where the structure is everything, but the shape is often irregular. Combining 3D printing and bioprinting elements enables increasingly effective research and treatment to continue.

With regards to the bioprinting itself – there are three methods of delivery: –

Extrusion

Bioinks is extruded through nozzles to create 3D structures – think of a gel being “printed” out into a petri-dish. This comes with limitations; however – nozzles can become clogged, and other variables affect the process, such as cell viability, concentration etc.

Inkjet

This “non-contact” printing technique uses droplet technology, but the size and placement precision can cause difficulties, and only low viscosity ink can be used.

Laser

This method uses laser technology to deposit biomaterials onto a substrate, but it can be a costly and time-consuming process in preparation and achieving precise cell placement.

Bioinks

As with the three types of bioprinting, there are different categories of bioinks – matrix, sacrificial and support, with matrix referring to “encapsulating” hydrogel inks – biomaterials that can be both printed AND form a compatible environment for living cells.

Sacrificial links are rather like the name suggests – bioinks that are printed but then removed (often self-eroding) to create empty channels/spaces.

Where matrix bioinks lack the stability to be printed on their own or take too long to “gel”,; sacrificial or support inks may also be used to create the necessary framework. These gels can be added singularly or form the composition of “hybrid” inks.

The right ink

All links need to have defined characteristics such as curing process, biological compatibility, interaction, and viscosity level to match up to printing requirements. As they are produced explicitly for 3D bioprinting cell culture applications, some of the most dependable yet versatile bioinks can be used with any extrusion printer, giving users the results, they seek.