Reinforced microfibers for soft hydrogels are a breakthrough for printed cartilage for 3D printed body parts

QUT biofabrication team has made a major breakthrough by 3D printing mechanically reinforced, tissue engineered constructs for the regeneration of body parts.

In an article published in Nature Communications, the biomedical engineers outlined how they had reinforced soft hydrogels via a 3D printed scaffold.

Professor Dietmar W. Hutmacher, from QUT’s Institute of Health and Biomedical Innovation, said nature often used fibre reinforcement to turn weak structures into outstanding mechanically robust ones.

“Such is the case with articular cartilage tissue, which is formed by stiff and strong collagen fibres intertwined within a very weak gel matrix of proteoglycans,” Professor Hutmacher said.

Fabrication of microfibre scaffolds. 3D scaffolds were fabricated from PCL by 3D printing, that is, melt-electrospinning in a direct writing mode. (a) Thin PCL fibres were stacked in a 0–90° orientation through combined extrusion and an electrostatic field

Nature Communications – Reinforcement of hydrogels using three-dimensionally printed microfibres

“By bringing this natural design perspective of fibre reinforcement into the field of tissue engineering (TE), we can learn a lot about how to choose an effective combination of matrix and reinforcement structure in order to achieve composite materials with enhanced mechanical properties for engineering body parts.”

Professor Hutmacher said hydrogels were favoured because they had excellent biological properties, however, the hydrogels currently available for tissue regeneration of the musculoskeletal system couldn’t meet the mechanical and biological requirements for successful outcomes.

“Our international biofabrication research team has found a way to reinforce these soft hydrogels via a 3D printed scaffold structure so that their stiffness and elasticity are close to that of cartilage tissues.”
Professor Hutmacher said the team had introduced organised, high-porosity microfiber networks that are printed using a new technique called “melt electrospinning writing”.

“We found that the stiffness of the gel/scaffold composites increased synergistically up to 54 times, compared with hydrogels or microfiber scaffolds alone,” he said.

“Computational modelling has shown that we can use these 3D-printed microfibres in different hydrogels and a large range of tissue engineering applications.”

Abstract

Despite intensive research, hydrogels currently available for tissue repair in the musculoskeletal system are unable to meet the mechanical, as well as the biological, requirements for successful outcomes. Here we reinforce soft hydrogels with highly organized, high-porosity microfibre networks that are 3D-printed with a technique termed as melt electrospinning writing. We show that the stiffness of the gel/scaffold composites increases synergistically (up to 54-fold), compared with hydrogels or microfibre scaffolds alone. Modelling affirms that reinforcement with defined microscale structures is applicable to numerous hydrogels. The stiffness and elasticity of the composites approach that of articular cartilage tissue. Human chondrocytes embedded in the composites are viable, retain their round morphology and are responsive to an in vitro physiological loading regime in terms of gene expression and matrix production. The current approach of reinforcing hydrogels with 3D-printed microfibres offers a fundament for producing tissue constructs with biological and mechanical compatibility.

Supplemental information

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