Cartilage – the connective tissue that provides a smooth, lubricated surface between joints in the body – is a structural marvel, but its limited capacity for self-repair complicates injury treatment. To boost the healing process, researchers have long been keen to find new cell-based therapies, and have identified cartilage as a promising candidate for tissue engineering.
“This idea was supported by the apparent morphological simplicity of cartilage – a tissue composed of a single cell type, namely chondrocytes,” explains Wojciech Święszkowski, a biomaterials expert based at Warsaw University of Technology.
His team – which includes Andrea Barbetta and a group of chemists at Sapienza University of Rome, and specialists in stem-cell research at Oslo University Hospital directed by Jan Brinchmann – is helping to advance cartilage regeneration through the development of 3D-printed biomimetic hydrogel scaffolds. To fabricate these intricate matrix structures for supporting cell growth, the researchers have developed custom apparatus that provides microfluidic control over the dispensing of bioink through co-axial nozzles.
According to Święszkowski, who has presented the work in the journal Biofabrication, the set-up unlocks a new level of printing accuracy for extrusion-based systems. “Using this apparatus, we can deposit cells with precision beyond the dimension of a single laid fibre,” he explains. “It means that extrusions can contain multiple cell types or biomaterials, which allows us to pattern 3D constructs that more closely mimic the body’s own tissue.”
The technique also makes advances in decoupling printing accuracy and precision from bioink rheology. “We can freely change bioink composition in terms of biopolymer content and/or cellular density, without changing printing conditions such as printing speed, layer thickness, or the distance between fibres,” Święszkowski comments.
This flexibility gives the team more freedom to tailor the structure and composition of the fibre. In the case of cartilage repair, the group has succeeded in bioprinting biomimetic extracellular matrices composed of methacrylated derivatives of gelatin, hyaluronic acid and chondroitin sulphate.
Święszkowski’s team also has projects running that focus on repairing bone, skeletal muscle, tendon and pancreatic tissue. Examining the performance of their fabricated designs, the researchers have shown that three-dimensional constructs bioprinted using the co-axial extrusion system exhibited functional features after culturing in the lab.
By James Tyrrell | physicsworld
Image Credit: James Tyrrell | physicsworld