The tubes containing the suspensionsof HUVECs in EGM were maintained under constant right-angled rotationalong the circumference for up to 2 h under a humidified environmentas the cells sedimented to attach to the PDMS walls during this period.Alternatively, the PDMS tubes could be placed in the incubator andflipped every 30 min for 2–4 times to enable uniform cell coating.