“We’re out of blood,” was the chilling statement released by Sichuan University School of Medicine in Chengdu.

4,700 people were left homeless following the earthquake which struck Chengdu yesterday. Rescuers and volunteers are still working through the rubble of the Tianfu Times Tower, but Chengdu’s hospitals are overwhelmed.

“We called for blood donors,” says Doctor Wang Changjiang, “but we can’t process the blood fast enough to meet our needs.”

Despite this critical shortage, no-one has died and Doctor Wang and her team have had more than enough blood. It just isn’t human.

“We’ve had ready availability of artificial blood in the NHS for the last three years,” says Haroun Kemp, an emergency coordinator in the British health service. “The moment we heard of the shortage, we offered to help.”

The artificial blood used by the NHS is based on a plastic polymer, is cheap and easy to produce with a shelf-life of four years. It requires dilution with sterile water, which allows it to take up less room in storage. A ton, equivalent to 5,000 units of human blood, was in Chengdu within five hours.

“It’s astonishing,” says Chen Shengyong, a nurse at Sichuan Hospital. “We had no need to do blood-typing, or worry about rare blood conditions. I’m told this is completely synthetic, yet our patients have responded better than we could have hoped.”

ANALYSIS >> SYNTHESIS: How this scenario came to be

June 2015: NHS sets 2017 target for artificial blood
“Scientists across the globe have been investigating for a number of years how to manufacture red blood cells to offer an alternative to donated blood to treat patients,” says Dr Nick Watkins, NHS Blood and Transplant Assistant Director of Research and Development.

With that the NHS sets itself the ambitious target of completing clinical trials for artificial blood by 2017.

85 million units of red blood cells are required for transfusion annually; that’s about 38 million liters of blood. And demand is growing at about 6-8% a year, while supply is growing at 2-3%. This is despite vast improvement in therapy around key-hole surgery or coronary bypasses where far less blood is now required.

Following the outbreak of Variant Creutzfeldt-Jakob disease in 1996, which caused 170 human cases of the illness, the UK does not use locally-donated blood plasma, but imports it from the US. Conversely, New York imports about 25% of its blood supply from Europe.

Donated blood is subjected to a plethora of tests, including for sexually transmissible diseases, Hepatitis B and C, and HIV. Then it needs to be typed as A, B, AB, or O and its Rhesus group.

“Human blood is great, but we can’t get enough of it, and we can’t get enough of the right type. What is needed is synthetic blood that meets all our requirements,” says Dr Watkins.

Those requirements are extensive. Firstly, it must be compatible with all blood-types, ensuring it can be used by anyone. It must be able to transport oxygen at least as efficiently as blood; and that is both in terms of its capacity to absorb oxygen, and to release it once it gets to its destination. It must last about 120 days once it is transfused to ensure that its rate of decay matches your body’s rate of production (otherwise it’s like having a continuous bleed and requires a just-as-continuous top-up).

And, if that isn’t enough, it must have similar properties to blood since your body control-systems are designed to deal with specific homeostatic pressures and flow-rates.

Dr Watkins grins, “Come back in 2017.”

August 2017: Competing types of synthetic blood go mainstream
A small protest meets journalists arriving at the National Blood Service at St George’s University of London. Placard-wielding demonstrators are concerned about the use of stem cells in synthetic blood.

“No to transgenic humans,” shouts one cardigan-wearing gentleman.

“It’s frustrating,” says Dr Jessica Matthews. “Our stem cells are harvested from donor umbilical cords and erythrocytes [red blood cells] don’t contain DNA anyway. There’s a certain demographic we just cannot reach.”

Few journalists are interested in the protests. Given the turnout, it appears that most are interested only in the NHS’ synthetic blood clinical trial results.

“The trial went better than we expected, with better patient outcomes, including much lower risk of adverse events,” says Dr Watkins. The trial went so well that, within the year, the NHS will be scaling production nationwide.

“But that’s not all. We would also like to announce a successful early-stage trial with the University of Sheffield.”

The University of Sheffield has been developing a plastic synthetic blood made from a dendrimer composed of repetitively-branched molecules forming a tree-like structure around an iron atom at the core. Dendrimers have been used in drug and gene delivery to protect their payload (or prevent adverse side-effects in the wrong place).

“Our results are promising, and we’re hoping to have commercial quantities ready for the market in two years,” says Dr Lance Twyman, from the Department of Chemistry at the University of Sheffield.

Dr Watkins grins, “Come back in 2019.”

April 2021: Successful transfusions without blood
Emergency responders receive the call at 04h16 on 19 April. An earthquake has hit Chengdu.

As China’s professional dispatchers and medical responders fly in from all across the country to respond to the call for aid, one thing becomes immediately apparent. “There isn’t going to be enough blood,” says Dr Wang Changjiang, of the Sichuan University School of Medicine.

Donors arrive but all available space is being used for patients. Hospitals as far as Hong Kong collect blood, but processing is taking too long.

Worse is to come. On 20 April nurses discover that a generator to the main blood bank at Sichuan University School of Medicine failed. All the blood needed to be discarded.

“We’ve had ready availability of artificial blood in the NHS for the last three years,” says Haroun Kemp, an emergency coordinator in the British health service. “The moment we heard of the shortage, we offered to help.”

The University of Sheffield’s synthetic blood received regulatory approval in the UK only months ago. “We have four tons in our warehouse waiting for distribution. The RAF arranged for a jet to pick up a ton and transport it to Chengdu.”

Haroun Kemp finds himself teaching Chinese nurses how to prepare the synthetic blood for transfusion for 214 emergency patients.

“It’s astonishing,” says Chen Shengyong, a nurse at Sichuan Hospital. “We had no need to do blood-typing, or worry about rare blood conditions. I’m told this is completely synthetic, yet our patients have responded better than we could have hoped.”