Researchers at Children's Hospital Boston have created blood vessels from genetically engineered cells that could secrete drug on demand directly into the bloodstream to combat anaemia.

Patients who rely on recombinant, protein-based drugs must often endure frequent injections, often several times a week, or intravenous therapy.

They have reversed anaemia in mice with engineered vessels secreting erythropoietin (EPO).

The technology could potentially be used to deliver other proteins such as Factor VIII and Factor IX for patients with hemophilia, alpha interferon for hepatitis C and interferon beta for multiple sclerosis, said the study's principal investigator, Juan Melero-Martin, PhD, of the Department of Cardiac Surgery at Children's.

Such drugs are currently made in bioreactors by engineered cells, and are very expensive to make in large amounts.

The researchers created the drug-secreting vessels by isolating endothelial colony-forming cells from human blood and inserting a gene instructing the cells to produce EPO.

They then added mesenchymal stem cells, suspended the cells in a gel, and injected this mixture into the mice, just under the skin. The cells spontaneously formed networks of blood vessels, lined with the engineered endothelial cells.

Within a week, the vessels hooked up with the animals' own vessels, releasing EPO into the bloodstream.

Tests showed that the drug circulated throughout the body and reversed anaemia in the mice; both induced by radiation (as often occurs in cancer patients) and by loss of kidney tissue (modelling chronic kidney failure).

Mice with the vessel implants had significantly higher hematocrits (a measure of red blood cell concentration) and recovered from anaemia more quickly than controls.

The discovery was reported in the November 17 issue of the journal Blood. (ANI)