Japan may have created artificial blood that works like the real thing

No blood group, no infection risk, no expiry for months. Researchers in Japan might just have developed artificial blood.These artificial red blood cells could transform how the world handles emergencies — from mass casualties to rural surgeries. The lab-made cells mimic real ones: they carry oxygen, stay stable at room temperature, and are made using expired donated blood that would otherwise be discarded.A recent Lancet report showed that India has one of the world’s highest blood shortages, with lack of awareness, sub-par infrastructure and a chronic shortage of voluntary donors worsening the crisis. As the country grapples with a rising demand for blood and a shrinking donor base, the idea of a blood substitute could be life changing. Developed by Professor Hiromi Sakai and his team at Nara Medical University, these stable, virus-free artificial red blood cells eliminate the need for blood type matching. This technology — now in clinical trials — could change the rules of transfusion medicine, and redefine how countries prepare for crises where real blood can’t reach in time.“They are also expected to respond to diseases and surgical procedures that cannot be treated by blood transfusions, and to unmet medical needs,” says Prof Sakai’s lab’s website.What exactly is artificial blood?Artificial blood isn’t a full replica of human blood. It doesn’t have white blood cells, or platelets. But it does what’s most vital in an emergency — carry oxygen. The Japanese researchers developed artificial red blood cells by encapsulating purified haemoglobin inside thin lipid-based structures, forming haemoglobin vesicles (HbVs). The artificial cells have a purplish color, unlike the common red color of blood, as they are made in a way that they do not oxidise until they are used. These vesicles are just 250 nanometers wide — small enough to flow through capillaries, just like natural red blood cells do.Unlike donated blood, HbVs don’t have a blood type, and don’t carry infection risks. They are made from expired red blood cells that would otherwise be discarded, or even from animal or lab-sourced haemoglobin. In essence, it's a purified, shelf-stable oxygen delivery system — without the usual complications of blood transfusions.Artificial blood offers several benefits over traditional blood donations. It eliminates the need for compatible testing, making it very useful in emergency situations, and can be stored at room temperature for up to two years, far exceeding the short shelf life (around 42 days) of donated blood. The blood was first tested on ratsIn tests on rats where over 90% of their blood was replaced with artificial red blood cells, key indicators like blood pressure, oxygen levels, and gas composition stayed within normal ranges. In fact, when researchers used a modified type of haemoglobin, it caused blood vessels to tighten and blood pressure to rise — a negative effect. But when they used their version of artificial red blood cells, the HbVs, these issues didn’t occur.The artificial blood was also tested to treat rats in shock from heavy blood loss. It worked well — oxygen delivery and blood flow were stable, and all the animals survived. It was also helpful in other experiments involving organ support, stroke, wound healing, and cancer treatment.After being injected, the artificial red blood cells naturally travelled to the spleen and liver, where they were broken down and cleared from the body within a week — just like old red blood cells. The spleen did get slightly enlarged for a short period of time, but soon returned to normal without causing any harm. Blood tests showed no health problems in the rats.Even when large doses — more than twice the animal’s total blood volume — were given over two weeks, the rats stayed healthy and continued to grow. There were no signs of toxic effects or damage in the organs. The next step: human trialsAfter completing safety tests in animals in early 2019, researchers began the first human trial (called First-in-Human or FIH) in October 2020. The trial was approved by Japan’s drug authority and the ethics committee at Hokkaido University, where the trial was held. Healthy adult men were given different doses of the artificial blood (called NMU-HbV): 10 mL, 50 mL, and 100 mL in three separate groups.The results were encouraging. No serious side effects were reported. Some participants had mild reactions like fever or discomfort from the injection, but these went away on their own. Blood tests, heart checks, and other health indicators showed no problems. In the group that received the highest dose (100 mL), the artificial haemoglobin stayed in the bloodstream for around 8 to 9 hours. Earlier tests had shown that the higher the dose, the longer it stays in the body — and future trials may show even better results. With this early success, researchers launched the next stage of the project in 2021. This involved planning for Phase Ib and Phase II trials. To include female participants, they first ran more safety tests on animals. The team then finalised the Phase Ib trial design, based on direct consultations with Japan’s drug regulator.For Phase II, they discussed using the artificial blood after a patient’s bleeding has already been stopped — to help stabilise oxygen levels in people with severe anemia. In March 2025, the scientists administered 100 to 400 millilitres of the artificial blood to 16 volunteers. If all goes to plan, the team hopes to make the blood available for real-world medical use by 2030.