Resolves as YES if at least 1 million synthetic blood vessels have been successfully implanted into 1 million (different) adult humans before January 1st 2035. This can occur anywhere on Earth.

Other organs:

Will we get synthetic lungs before 2035?39%‌

Will we get synthetic hearts before 2035?65%‌

Will we get synthetic livers before 2035?33%‌

Will we get synthetic kidneys before 2035?25%‌

Will we get synthetic eyes before 2035?41%‌

Will we get synthetic blood vessels before 2035?59%‌ (this question)

Will we get synthetic stomachs before 2035?43%‌

In the context of this question, a synthetic blood vessel is defined as an organ that fulfils broadly the same function as the original tissue it is designed to replace, despite having never been present inside a human body. This definition includes, but is not limited to, biological vessels grown on scaffolds from the patient's stem cells, artificial vessels that do not contain biological cells and synthetic vessels that have both biological and non-biological components.

Successful implantation is defined as the organ continuing to operate for at least 12 months subsequent to the operation. If multiple operations are required, then this clock starts at the final operation. A healthy threshold of operation is not defined for this question, only that the transplant is still considered functional and the clinicians do not consider it appropriate to remove it.

These synthetic organs must have been completely implanted into the human, and cannot have significant components located outside of the patient's body. However, these devices are allowed to have external ports such as electrical sockets and tubes for fluids (although this is probably not likely to be needed in the case of synthetic blood vessels). The devices must be able to operate autonomously for a period of at least 12 hours without being connected to these external ports.

Various forms of maintenance over the 12 month duration are permitted, provided the synthetic vessels are not removed from the patient's body during these operations. Removing and replacing components of the organs is permitted.