Modified Red Blood Cells Form Clots in Seconds and Reduce Blood Loss in Rat Study

Researchers have developed a method to modify red blood cells, enabling them to form clots almost immediately in severe wounds, according to a study published in Nature. In experiments with rats, the modified cells triggered clotting in less than 5 seconds for liver injuries, compared to 265 seconds in untreated cases.

This innovation, led by Jianyu Li at McGill University in Montreal, Canada, could address the global toll of blood loss, which kills around 2 million people worldwide each year.

The process begins by extracting blood from rats and separating its cellular components. Scientists then add chemicals that function like handles, with one end attaching to proteins on the red blood cells' surface and the other linking to a long-chain molecule that connects cells. After incorporating this long-chain molecule, the modified cells are reintroduced to the blood plasma.

When injected into severe liver wounds in rats, the treated plasma produced dramatic results. Treated rats lost only 24 milligrams of blood, versus nearly 2000 milligrams in the untreated group. Red blood cells, which primarily carry oxygen, also combine with platelets and fibrin to create a sticky mesh that plugs injuries, forming the bulk of the blood clot.

These engineered clots proved more durable than natural ones, lasting one to two months rather than breaking down within days. The team observed no safety concerns during this period. 'We saw and used the elephant in the room,' said Jianyu Li, referring to the potential to strengthen the inherently fragile red blood cells.

Hyunwoo Yuk, founder of SanaHeal, a company developing bioadhesive technologies in Boston, Massachusetts, described the work as exciting. 'It is exciting work that shows a new design method for cell-based biomaterials for surgical and regenerative applications,' Yuk said. The researchers have applied for a patent on the technique.

The study highlights how red blood cells make up the bulk of the blood clot plug, building on their role in combining with platelets and fibrin in response to injury. By enhancing this natural process, the modification addresses limitations of current treatments, such as costly transfusions or bandages that may trigger immune reactions.

The team envisions preparing the treatment from a patient's blood in under 30 minutes for planned surgeries or from blood-bank samples for emergencies.

1038/s41586-026-10412-y, the research opens avenues for further exploration. Li's group plans additional studies to refine the approach. While existing treatments offer longer storage, the modified cells could be refrigerated for at least a month, providing a rapid-response option for severe bleeding.