Misshapen red blood cells could be used as a tool to kill cancer cells in mice, research in the journal Plos One shows.

Sickle-shaped cells can stick together in blood vessels surrounding tumours in mice and block blood flowing to the cancer, researchers says.

The irregularly shaped cells can also deposit toxic residues on the tumour, leading to cancer cell death.

This research focuses on oxygen-poor areas in tumours which have proven difficult to treat in humans.

The US researchers from Duke University and Jenomic, a private research company, gave a fluorescent sickle-cell solution to mice with cancer and watched what happened inside their systems.

Within five minutes the misshapen cells began to stick like 'Velcro' to blood vessels near the oxygen-starved areas of the tumour, Prof Mark Dewhirst co-author of the study, from Duke University, said.
Exclusive target

At 30 minutes the cells formed clots and began to block small blood vessels which fed the tumour.

And the sickle-shaped cells exclusively targeted the oxygen-low areas of tumour, which can become increasingly aggressive forms of cancer in humans.

"We found that sickle cells show a highly unique natural attraction to oxygen-deprived tumours.

"Once clustered within the tumour, the sickle cells deposit a toxic residue... causing tumour cell death," Dr David Terman, a co-author of the study and head of molecular genetics at Jenomic said.

Sickle-shaped cells are normally present in humans who inherit a genetic condition known as sickle cell anaemia.

Unlike normal disc-shaped blood cells, these crescent-moon shaped cells do not flow smoothly through blood vessels and can clump together to block blood supply.

This can result in a sickle crisis - often causing severe pain in the affected region and sometimes a complete and dangerous stop to blood flow in the area.

"The very qualities that make sickle cells a danger to people with the inherited genetic disorder can be turned against tumours to fight cancer," said Dr Terman.

"This is an intriguing new tactic for destroying tumours that are resistant to standard treatments, but the research was carried out in mice so the next challenge will be to show whether this approach is safe and effective in people with cancer," said Dr Emma Smith of Cancer Research UK.

The researchers say their approach could be directed at breast cancers, prostate cancers and many other tumours that develop resistance to current therapies, once more animal studies and human trials have been carried out.