Scientists at Osaka University have used silk nanofibres, which they produced by mechanical disintegration, to enhance the 3D printing process so that the cells or cell assemblies are not damaged. Silk is considered to be safe for humans. Therefore, its use will help bring 3D cell printing research out of the laboratory into real-world biomedical use. To obtain the fibres, the researchers started with virgin silk, then removed the protein sericin from it because this protein causes inflammation in patients. Next, the researchers ground the remaining biocompatible material into nanofibres. The fibres can be sterilized without damaging them for medical use, with common laboratory equipment. The main purpose of the fibres was to ensure that the cells in the bioink retained their 3D positioning after printing without damaging the cells. The fibres fulfil this purpose by enhancing the integrity of the bioink and minimising the damaging high mechanical stresses often placed on cells during printing. The fibres help printed configurations retain their structural integrity after printing. For example, a nose-shaped configuration retained its shape only when printed with bioink containing the silk fibres. Over 85 per cent of the cells in the bioink remained alive after a week in the printed bioink with or without the added fibres, indicating that adding the fibres did not damage the cells. Current cell printing technology often heavily damages cells or does not retain the intended shape for long. The research here helps overcome these limitations in a way that will help advance drug discovery, regenerative medicine, and many other ongoing high-impact biomedical research fields, and has the potential to reinvigorate the silk industry.
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