Correction to: Nature Biomedical Engineering, published online 19 April 2021.

In the version of this Article originally published, in Fig. 2a the images labelled ‘3 d’, ‘5 d’ and ‘7 d’ in the top row (‘Stiff hydrogels’) were accidentally duplicated in the bottom row (‘Soft hydrogels’). The original and corrected versions of Fig. 2a are shown below. All versions of the Article have been amended.

Fig. 2
figure 1

Original and Corrected.