Bio-engineering self-sustaining blood vessels

Researchers have bio-engineered blood vessels that when implanted into a patient are quickly colonised by native cells and become self-sustaining.

A team led by Robert Kirkton of US-based regenerative medical tech company Humacyte Inc created biodegradable scaffolds in the form of blood vessels and then seeded them human vascular cells before incubating them in a bioreactor for eight weeks.

After the incubation, Kirkton and his colleagues removed all the cellular material, leaving behind what they term human acellular vessels (HAVs).

In a four year phase II clinical trial, the HAVs were implanted into 60 patients with end-stage kidney failure, where they served as entry ports for hemodialysis treatments – an approach which requires access to healthy blood vessels.

In a paper published in the journal Science Translational Medicine, the researchers report that the HAVs demonstrated strong mechanical and structural integrity. Within weeks of implantation, they had become populated by the patients’ own cells and microvasculature.

In effect, the researchers write, the acellular vessels transformed into “functional multilayered living tissues that maintain blood transport and exhibit self-healing after cannulation injury, effectively rendering these vessels like the patient’s own blood vessel”.

Fresh clinical trials are currently under way, and if these pan out the HAVs developed by Kirkton and colleagues could represent an end-run around rejection issues that arise from the use of human or animal donors as sources of replacement blood vessels.

“With continued clinical evaluation and development of scalable and cost-efficient manufacturing processes, readily available tissue engineered human blood vessels may offer a promising ‘off-the-shelf’ and biocompatible alternative,” the researchers suggest.