No fully approved artificial blood product exists for general clinical use in the United States or Europe, despite more than four decades of research. The field has produced two broad families of substitutes, hemoglobin-based oxygen carriers and perfluorocarbon emulsions, along with newer approaches like lab-grown red blood cells and synthetic nanoparticles. Each has shown genuine promise in specific settings, yet each has also run into biological and economic barriers that have kept artificial blood just out of reach. The science, however, has not stalled. Recent years have seen breakthroughs in nanoparticle design, bioreactor engineering, and even the first human trials of laboratory-cultured red blood cells, all of which are reshaping what “artificial blood” could look like within the next decade.
Two Families of Blood Substitutes
The most developed category of artificial blood is the hemoglobin-based oxygen carrier, or HBOC. These products take hemoglobin, the protein inside red blood cells that binds and releases oxygen, and process it so it can circulate freely in the bloodstream without needing a red blood cell membrane around it. Hemoglobin can come from expired donated human blood, from bovine sources, or from genetically engineered bacteria. Once extracted, it undergoes chemical modifications such as polymerization, cross-linking, or attachment of polyethylene glycol (PEG) chains to increase its size, extend how long it circulates, and reduce toxicity.1PubMed Central. Comparison of the Pharmacokinetic Properties of Hemoglobin-Based Oxygen Carriers Because the hemoglobin is stripped from cells, HBOCs do not carry blood-type antigens on their surface, which means they can be given to any patient without blood typing or cross-matching.2International Journal of Research in Pharmacy and Allied Science. Plastic Blood: Synthetic Blood Substitutes in Emergency Medicine for Patient Transfusion
The second family is perfluorocarbon (PFC) emulsions. These are entirely synthetic, carbon-fluorine compounds that dissolve oxygen and carbon dioxide directly rather than binding them chemically the way hemoglobin does.3PubMed Central. Perfluorocarbon-based oxygen carriers: from physics to physiology The oxygen simply sits between the PFC molecules and is released when surrounding tissue has a lower oxygen concentration. PFCs are also blood-type neutral and can be manufactured without any biological starting material. After doing their job, PFC particles are engulfed by immune cells and eventually exhaled through the lungs, a clearance process that is reversible and does not cause lasting tissue damage.4PubMed. Pharmacokinetics and side effects of perfluorocarbon-based blood substitutes However, PFCs carry less oxygen per volume than hemoglobin-based products and typically require the patient to breathe supplemental high-concentration oxygen to work well, which limits where and how they can be used.
Why Hemoglobin Outside a Red Blood Cell Causes Problems
The core challenge for HBOCs has been a side effect that sounds counterintuitive: a product designed to deliver oxygen can make blood pressure spike dangerously. The reason is nitric oxide, a small signaling molecule that your blood vessels constantly produce to stay relaxed and open. Free hemoglobin floating in plasma is extremely good at grabbing nitric oxide, far better than hemoglobin safely tucked inside a red blood cell. When the free hemoglobin scavenges that nitric oxide, blood vessels constrict, and blood pressure rises.5Nature Biotechnology. Rate of reaction with nitric oxide determines the hypertensive effect of cell-free hemoglobin Research using recombinant hemoglobins engineered to react with nitric oxide at different speeds confirmed that the rate of that reaction directly predicts how much blood pressure goes up.5Nature Biotechnology. Rate of reaction with nitric oxide determines the hypertensive effect of cell-free hemoglobin
This is not just a theoretical concern. The same nitric oxide scavenging happens with old stored blood: as red blood cells break down over weeks in a blood bag, they release cell-free hemoglobin into the surrounding plasma, and that hemoglobin consumes nitric oxide in direct proportion to its concentration.6PubMed Central. Nitric Oxide Scavenging by Red Cell Microparticles and Cell Free Hemoglobin as a Mechanism for the Red Cell Storage Lesion So HBOCs essentially concentrate a problem that already exists at low levels in conventional transfusions. Strategies to counter it have included making hemoglobin molecules larger (so they cannot slip into the space between vessel walls as easily), co-administering nitric oxide donors, and engineering hemoglobin variants with slower nitric oxide reaction rates.7PubMed Central. Reversal of hemoglobin-induced vasoconstriction with sustained release of nitric oxide Novel chemical approaches like “inside-out” PEGylation, which wraps multiple hemoglobin molecules around a single polymer backbone rather than coating each molecule individually, aim to shield the reactive sites from nitric oxide while preserving oxygen delivery.8PubMed. “Inside-Out” PEGylation of Bovine β-Cross-Linked Hemoglobin
A Troubled Clinical Track Record
Despite decades of work, no HBOC has won FDA approval for clinical use. Early clinical trials using purified native hemoglobin revealed hypertension from vasoconstriction as well as signs of damage to multiple organs. Later-generation products that cross-linked or polymerized hemoglobin improved the profile somewhat, but large-scale trials continued to show elevated rates of adverse events or failed to meet their clinical endpoints.9PubMed Central. Artificial Oxygen Carriers: Lessons From Hemoglobin-Based Oxygen Carrier Clinical Trials and Current Development Efforts The reactive heme center at the heart of hemoglobin remained a source of problems: besides scavenging nitric oxide, it generates reactive oxygen species and can trigger sterile inflammation.9PubMed Central. Artificial Oxygen Carriers: Lessons From Hemoglobin-Based Oxygen Carrier Clinical Trials and Current Development Efforts
One HBOC, a bovine-derived product called Hemopure, gained approval in South Africa in 2001 for treating acute anemia, but that remains an outlier. In the United States and Europe, regulators have consistently judged the risk-benefit balance unfavorable for general transfusion. The field’s response has been to move toward more sophisticated molecular engineering and toward clinical niches where the risk calculus is different, such as organ preservation or remote trauma care where no donated blood is available at all.
Lab-Grown Red Blood Cells
A fundamentally different approach sidesteps free hemoglobin entirely: grow actual red blood cells in the laboratory. Starting from stem cells, whether drawn from adult blood or derived from induced pluripotent stem cells (iPSCs), researchers can coax the cells through the same developmental stages they would follow in bone marrow, ending up with enucleated red blood cells that look and function like the ones your body makes naturally. Improved culture protocols have eliminated the need for animal-derived components and dramatically reduced the amount of expensive transferrin protein required, while also boosting the rate at which these cells shed their nuclei, a critical final step in red blood cell maturation.10Experimental Hematology. PSC-RED and MNC-RED: Albumin-free and low-transferrin robust erythroid differentiation protocols to produce human enucleated red blood cells
The first-ever trial to transfuse lab-grown red blood cells into humans, called RESTORE, began in the United Kingdom. It is comparing how long laboratory-made red blood cells survive in the body against standard donated red blood cells.11BioScientist: The Salford Biomedicine Society Magazine. The RESTORE trial’s implications on the future of blood transfusions The trial is small, a proof-of-concept study, but it represents a genuine milestone: for the first time, cells manufactured entirely in a lab are circulating in human volunteers.
The bottleneck is scale. A single unit of transfusable blood contains roughly a trillion red blood cells. Current iPSC differentiation protocols struggle to produce that many cells efficiently, hampered by developmental immaturity of the cells, low enucleation rates in the range of five to twenty-five percent, and culture conditions that do not mimic what happens inside the body.12PubMed Central. Large-Scale Production of Transfusion-Ready Red Blood Cells From Induced Pluripotent Stem Cells Early bioreactor work found that producing one unit of red blood cell precursors required about 500 liters of culture media, and an unexplained inhibitory factor in the growth environment capped productivity regardless of how well nutrients and oxygen were supplied.13PubMed Central. The productivity limit of manufacturing blood cell therapy in scalable stirred bioreactors New 3D culture systems and bioreactor designs are being explored to break through these limits, but further research is needed before lab-grown blood can be manufactured at clinically useful volumes.14PubMed Central. Current status of red blood cell manufacturing in 3D culture and bioreactors
Synthetic Nanoparticles and Hybrid Designs
Some researchers have taken a different tack altogether, building artificial red blood cells from scratch using synthetic materials. One of the most advanced examples is ErythroMer, a nanoparticle made from a lipid-polymer hybrid shell that encapsulates hemoglobin along with pH-sensitive compounds. The pH sensitivity matters: in tissues that are low on oxygen, the local environment becomes more acidic, and the particle responds by releasing its oxygen preferentially where it is needed most. ErythroMer can also be freeze-dried for storage and reconstituted with saline, giving it a shelf life and portability that no donated blood product can match.15Nature Communications. Artificial cells for in vivo biomedical applications through red blood cell biomimicry
The hybrid design strategy, combining lipids for biocompatibility with polymers for structural toughness, addresses one of the recurring themes in artificial blood development: you need the product to behave enough like a natural cell to avoid triggering immune reactions, but you also need it to survive manufacturing, storage, and reconstitution processes that would destroy a real cell. Early animal results with ErythroMer have been promising, though it has not yet entered human trials.
Artificial Platelets
Blood does more than carry oxygen. Platelets, the cell fragments responsible for clotting, are just as critical in trauma and surgery. Donated platelets have an even shorter shelf life than red blood cells, typically only five days under constant gentle agitation at room temperature, which makes them chronically scarce. Researchers have developed synthetic platelet nanoparticles that mimic how natural platelets stick to damaged blood vessels and recruit more platelets to the wound site. In a rat model of major trauma, these synthetic platelets halved bleeding time and outperformed recombinant clotting factor VIIa, a drug currently used for uncontrolled bleeding. The nanoparticles cleared the body within 24 hours and caused no complications out to seven days.16PubMed Central. Synthetic Platelets: Nanotechnology to Halt Bleeding
A more advanced version called SynthoPlate was subsequently tested in a pig model simulating traumatic arterial hemorrhage, one of the most lethal types of injury. When administered intravenously within the “golden hour” after injury, SynthoPlate reduced blood loss, stabilized blood pressure, and significantly improved survival.17Scientific Reports. Intravenous synthetic platelet (SynthoPlate) nanoconstructs reduce bleeding and improve ‘golden hour’ survival in a porcine model of traumatic arterial hemorrhage The ultimate goal is to combine platelet-mimicking particles with oxygen-carrying particles and plasma to create a complete biosynthetic whole blood surrogate. Early proof-of-concept work has already demonstrated the feasibility of that idea by treating hemorrhagic injury in rabbits with a combination of hemostatic liposomes and hemoglobin-loaded liposomes.18PubMed Central. Bioinspired Artificial Platelets: Past, Present and Future
Trauma Care and Remote Medicine
The strongest near-term case for artificial blood is not replacing the blood supply at your local hospital. It is getting oxygen-carrying capacity to places where donated blood simply cannot go. Blood products need refrigeration, have limited shelf lives, and must be matched to the recipient’s blood type, all of which are logistical nightmares in a combat zone, a rural clinic hours from a blood bank, or the scene of a mass casualty event. An artificial blood product that can sit at room temperature for months, requires no typing, and is free from bloodborne pathogens would change the calculus of emergency medicine.19PubMed Central. Artificial Blood: A Futuristic Dimension of Modern Day Transfusion Sciences
Military medical planners have been particularly vocal about this need. The ability to carry a freeze-dried product in a medic’s pack and reconstitute it in the field could save lives that are currently lost to hemorrhagic shock before evacuation. Similarly, ambulance services in remote regions and disaster-response teams operating where cold-chain logistics break down stand to benefit enormously. The product does not need to be a perfect replacement for whole blood in these scenarios. It needs to buy time, maintaining tissue oxygenation and blood volume for the hours it takes to get a patient to definitive care.
Organ Preservation Outside the Body
While artificial blood for transfusion has struggled to reach the clinic, a quieter success story has been unfolding in organ transplantation. When a donor kidney or liver is kept alive outside the body using machine perfusion, it needs an oxygen-carrying fluid to maintain the organ’s metabolic activity. Packed red blood cells can serve this role, but they introduce their own complexities: type matching, limited availability, and potential for contamination. In a study perfusing 14 human kidneys at body temperature for six hours, an HBOC solution performed comparably to packed red blood cells on measures of blood flow, oxygen consumption, and tissue energy levels, with no histological evidence of damage from the HBOC. Lactic acid levels were actually higher in the kidneys perfused with real blood.20PubMed Central. Synthetic hemoglobin-based oxygen carriers are an acceptable alternative for packed red blood cells in normothermic kidney perfusion Other groups have confirmed that HBOCs can maintain metabolic activity in preserved kidneys at physiologic levels, offering a convenient off-the-shelf alternative that does not depend on donor blood availability.21Journal of Anesthesia and Translational Medicine. Review Applications of Blood Substitutes in Transplantation Surgery: Where Are We Now? – Section: Kidney preservation
This application sidesteps the biggest safety hurdles facing HBOCs in living patients. The hemoglobin is circulating through an organ on a machine, not through a person’s entire vascular system, so the nitric oxide scavenging and vasoconstriction issues are far less relevant. It is entirely possible that artificial oxygen carriers find their first widespread clinical use in transplant surgery rather than in transfusion medicine.
Turning Donated Blood Into Universal Blood
One approach to the blood-supply problem does not involve making artificial blood at all but instead converts the blood we already collect into a universally compatible type. The difference between type A, B, AB, and O blood comes down to sugar molecules on the red blood cell surface. Type O cells lack the extra sugars that A and B cells carry, which is why O-negative blood can be given to anyone. Researchers have identified enzymes, specific glycosidases, that can clip those extra sugars off A or B red blood cells and convert them to functional type O cells.22PubMed Central. Toward universal donor blood: Enzymatic conversion of A and B to O type If this enzymatic conversion could be done efficiently and affordably, it would effectively make most of the donated blood supply universally transfusable, which would relieve chronic shortages of O-negative units without requiring any synthetic product at all.
This is a complementary rather than competing approach. Enzymatic conversion addresses the blood-type matching problem but does nothing about pathogen risk, shelf life, cold-chain logistics, or the fundamental reliance on voluntary donors. Artificial oxygen carriers address those issues but face their own safety and manufacturing challenges. The two strategies could coexist, with enzymatic conversion stretching the existing supply and artificial products filling gaps where donated blood cannot reach.
The Cost Problem
Even if every scientific hurdle were cleared tomorrow, economics would still stand in the way of widespread adoption. A unit of donated blood costs roughly $250 to $300 to acquire from a blood supplier in the United States.23Annals of Blood. New developments and future trends of artificial blood Artificial blood products, whether HBOC-based, PFC-based, or lab-grown, face enormous research and development costs, long development timelines, and manufacturing processes that have not yet achieved economies of scale. For lab-grown red blood cells, the sheer volume of culture media and growth factors required to produce a single transfusable unit dwarfs anything the current biopharmaceutical industry routinely handles. Limited scalability and manufacturing economics currently prevent widespread adoption in most parts of the world.23Annals of Blood. New developments and future trends of artificial blood
That said, cost calculations change depending on the setting. In a military forward operating base where no blood bank exists, or in a developing country where the infrastructure for blood collection, testing, and cold-chain storage barely functions, the relevant comparison is not “artificial blood versus $300 donated blood.” It is “artificial blood versus no blood at all.” In those contexts, even a product that costs several times more per unit could be cost-effective if it prevents deaths or reduces the logistical burden of maintaining a perishable blood supply in hostile conditions.
Perfluorocarbon Clearance and Side Effects
PFC emulsions have their own distinct safety profile that differs from HBOCs. Because PFC particles are inert synthetic compounds, they do not trigger the hemoglobin-related problems of vasoconstriction or oxidative stress. Instead, the body clears them through its normal immune housekeeping: macrophages in the liver and spleen engulf the PFC droplets, and the compounds are ultimately exhaled through the lungs. This process causes predictable, dose-related effects, including skin flushing and mild fever at lower doses and temporary macrophage enlargement at higher doses. These effects are reversible and do not result in permanent tissue damage, even with prolonged exposure.4PubMed. Pharmacokinetics and side effects of perfluorocarbon-based blood substitutes
One concern specific to PFCs is their temporary suppression of the reticuloendothelial system, the network of immune cells that clears damaged cells and debris from the bloodstream. An early PFC product called Fluosol-DA, tested at moderate doses, caused a transient block of this clearance system that lasted up to a week.24PubMed. Effect of a perfluorocarbon emulsion (Fluosol-DA) on reticuloendothelial system clearance function At very high or repeated doses, PFC particles can redistribute to tissues beyond the liver and spleen, and some animal species have shown reversible increases in pulmonary residual volume from trapped gas. These are manageable issues in a controlled clinical setting but add complexity to dosing protocols, especially if repeated administrations are needed.
Religious and Ethical Considerations
One community with an especially strong interest in artificial blood is Jehovah’s Witnesses, who refuse whole blood transfusions and primary blood components such as red cells, white cells, platelets, and plasma on religious grounds. Their religious leadership has not formally ruled on hemoglobin-based oxygen carriers or perfluorocarbon emulsions, leaving individual members to decide based on personal conscience whether to accept these products.25PubMed Central. Jehovah’s Witnesses and artificial blood For surgeons and anesthesiologists who treat Jehovah’s Witness patients, an effective artificial oxygen carrier would open up treatment options that are currently off the table, particularly in surgeries where significant blood loss is expected.
Beyond religious contexts, artificial blood raises its own ethical questions. If lab-grown red blood cells become viable, should they be allocated first to patients with rare blood types who already face chronic shortages? If freeze-dried oxygen carriers are stockpiled for military use, should civilian emergency services have equal access? And if artificial blood products eventually become cheap enough for routine use in wealthy countries, does the global health community have an obligation to make them available in low-income settings where donated blood is already dangerously scarce? These are not hypothetical questions for a distant future. The RESTORE trial is already underway, nanoparticles like ErythroMer are progressing toward human studies, and military funding agencies are actively investing in field-deployable oxygen carriers. The policy conversations need to keep pace with the science.
Borrowing From Marine Biology
Some of the most creative work in the field draws on organisms that solved oxygen transport problems millions of years ago. The lugworm Arenicola marina, a common marine invertebrate that lives buried in sand on tidal flats, produces an extracellular hemoglobin called M101 that is naturally large, naturally stable outside a cell, and naturally resistant to some of the problems that plague mammalian hemoglobin when it escapes from red blood cells. M101 has shown oxygen-carrying efficiency along with anti-inflammatory, antibacterial, and antioxidant properties, and has demonstrated promise as an additive to organ preservation solutions, where it reduces the tissue damage associated with interrupting and restoring blood flow.26PubMed Central. Therapeutic Potential of Hemoglobin Derived from the Marine Worm Arenicola marina (M101): A Literature Review of a Breakthrough Innovation
The appeal of borrowing from invertebrate biology is that evolution has already done some of the engineering work. Mammalian hemoglobin evolved to function inside a red blood cell, surrounded by enzymes that protect it from oxidation and tightly regulate its oxygen release. Strip away that cellular machinery and problems follow. Invertebrate hemoglobins like M101, on the other hand, evolved to function in the open bloodstream of animals with no red blood cells at all. They are naturally suited to the very application researchers are trying to engineer from scratch. Whether M101 or something inspired by it can be produced at useful scale and navigate human clinical trials remains to be seen, but it represents one of the more elegant approaches in a field that has learned, the hard way, that brute-force chemistry is not always enough.