Blood Substitutes and Artificial Blood: 7 Types Researchers Are Developing

There is no substitute for human blood. That statement has been true for over a century of transfusion medicine — but researchers have been working to change it for decades, driven by three persistent problems: blood shortages, storage limitations, and the ever-present risk of infectious disease transmission.

Simple volume expanders like Ringer’s lactate and colloid solutions can manage blood losses up to roughly 50% by maintaining blood pressure and fluid balance. But they carry no oxygen. Developing something that actually replicates blood’s oxygen transport function — safely, stably, and without the need for refrigeration or type-matching — remains one of medicine’s grand challenges.

Here are the seven major approaches researchers have pursued.

1. Antigen Camouflage

The concept: Rather than creating artificial red cells from scratch, what if you could make real red cells “invisible” to the immune system?

Researchers have developed techniques to coat the surface of red blood cells with polyethylene glycol (PEG), a polymer widely used in pharmaceuticals and food processing because the body’s immune system largely ignores it. The PEG coating physically masks the antigens on the cell surface — the proteins that define blood type and trigger immune rejection.

The result is a cell that retains its oxygen-carrying hemoglobin but can no longer be identified as type A, B, or O. In theory, PEG-coated cells would function as a universal donor product, compatible with any recipient.

Where it stands: This approach shows particular promise for patients who require repeated transfusions and develop alloantibodies — antibodies against donor red cell antigens that make finding compatible blood increasingly difficult. PEG camouflage could sidestep that escalating incompatibility.

2. Perfluorocarbon-Based Products

The concept: Perfluorocarbons (PFCs) are synthetic fluorinated compounds with a remarkable property — they dissolve oxygen at very high concentrations. Oxycyte, one of the most studied PFC products, can carry approximately five times more oxygen per unit volume than natural hemoglobin.

PFC oxygen carriers are formulated as tiny microdroplets that circulate through the bloodstream. Their small size allows them to reach tissue beds that standard red cells — much larger — may not penetrate easily in critically injured or inflamed tissue.

Key advantages:

• Requires no blood typing — compatible with all patients
• Can be stored at room temperature
• No infectious disease risk (fully synthetic)
• Microdroplets can access constricted capillaries

Where it stands: PFC products have been tested in clinical trials for applications including surgery and stroke treatment. The main limitation is that patients must breathe supplemental oxygen to maximize the amount the product can carry — PFCs dissolve oxygen but don’t bind it the way hemoglobin does, so partial pressure matters.

3. Recombinant Plasma Proteins

The concept: Instead of replacing red cells, recombinant technology targets plasma proteins — specifically clotting factors and albumin that can be manufactured without any human blood.

Using genetic engineering, scientists have inserted genes for human proteins (including Factor VIII and Factor IX, the deficient proteins in hemophilia A and B) into cell lines that produce them in culture. The resulting proteins are structurally identical to their natural counterparts but free from human blood-borne pathogens.

Why it matters: The hemophilia community suffered catastrophic HIV and hepatitis C infections in the 1980s and early 1990s from pooled plasma-derived clotting factors. Recombinant alternatives effectively ended that risk. FDA-approved recombinant Factor VIII and Factor IX are now standard of care in many countries.

Albumin — the most abundant plasma protein, critical for maintaining blood pressure and transporting drugs — is a current target for recombinant production to reduce dependence on plasma donations.

4. Transgenic Therapeutic Proteins

The concept: What if farm animals could serve as bioreactors for human blood proteins?

Transgenic animal research has successfully introduced human genes into livestock — primarily sheep, goats, and cattle — that then express human proteins in their milk. Milking these animals yields large quantities of protein that can be purified for medical use.

Claimed advantages:

• Virtually unlimited production capacity
• Substantially lower manufacturing costs than cell culture
• Freedom from human bloodborne diseases
• Scalable without large bioreactor investment

Where it stands: Human coagulation factors produced in transgenic animal milk have reached clinical research stages. Regulatory approval has been granted for a small number of transgenic animal-derived proteins in Europe and the United States, though the approach remains controversial and faces scrutiny regarding long-term safety and consistency.

5. Bovine-Derived Hemoglobin (Hemopure)

The concept: Hemoglobin — the actual oxygen-carrying molecule — can be extracted from bovine (cow) blood, purified, chemically modified to improve stability, and administered as an infusion.

Hemopure (hemoglobin glutamer-250, bovine) has been the most extensively studied hemoglobin-based oxygen carrier. Because it uses hemoglobin outside of red cells (a cell-free solution), it doesn’t require blood type matching and can be stored at room temperature for extended periods.

Clinical results: Trials demonstrated that 27% of patients who received Hemopure required no blood transfusions during the follow-up period. It has been approved for use in South Africa and has been used under compassionate use authorization in emergency situations.

Limitations: Cell-free hemoglobin solutions tend to scavenge nitric oxide, causing vasoconstriction (blood vessel narrowing). This cardiovascular side effect has been the primary regulatory obstacle to broader approval in the United States and Europe.

6. Modified Hemoglobin Solutions

The concept: Similar to bovine hemoglobin, this approach uses human or recombinant hemoglobin that’s been chemically modified — polymerized, conjugated, or encapsulated — to extend its circulation time and reduce the toxicity associated with free hemoglobin in the bloodstream.

PolyHeme, a polymerized human hemoglobin solution, was one of the most visible products in this category. It could be stored at room temperature for extended periods and was evaluated for trauma use — specifically, whether it could be administered in the field before hospital arrival when blood typing is impossible.

The ongoing challenge: Vasoconstriction remains the key obstacle. When hemoglobin circulates outside the protective environment of a red cell membrane, it interacts with vascular biology in ways that drive up blood pressure and can reduce blood flow to critical organs. Encapsulating hemoglobin in synthetic membranes (artificial red cells) is one proposed solution, but manufacturing these at scale remains technically difficult.

7. Platelet Substitutes

The concept: Platelets — the clotting cells depleted by chemotherapy and bone marrow failure — are among the most perishable blood products, lasting only five days. A stable, storable platelet substitute would transform care for cancer patients.

Two products have reached clinical study:

Synthocytes are polymerized albumin microspheres that mimic the platelet surface, activating the clotting cascade at sites of vascular injury without requiring living cells.

Cyplex is a freeze-dried platelet membrane preparation that retains some clotting activity after reconstitution.

The appeal: Compared to donated platelets, these substitutes would have dramatically longer shelf lives, no infection risk, and no HLA compatibility concerns. For thrombocytopenic cancer patients — one of the most demanding consumers of blood center platelet supplies — a stable alternative would be a significant advance.

Where it stands: Neither product has achieved FDA approval. Demonstrating adequate efficacy compared to real platelets has been the primary obstacle.

What All Substitutes Would Offer

Despite their differences in approach and mechanism, all successful blood substitutes would share several core advantages over donated human blood:

• Universal compatibility: No blood typing required — usable in any patient without delay
• Pathogen-free: No risk of hepatitis, HIV, or other transmissible infections
• Extended shelf life: Months or years without refrigeration, compared to days or weeks for donated components
• Reliable supply: Manufacturing capacity that scales with demand, unconstrained by donor availability
• Consistent quality: Predictable composition from batch to batch

The gap between this ideal and current reality explains why human blood donation remains essential. Understanding blood products and the complex needs they serve also clarifies why no single substitute can replace all of them simultaneously — the biology is simply too varied.

Research continues, driven by the persistent reality that blood facts make stark: supply never fully meets demand, and the patients who need blood most urgently are often those in settings where stored human blood isn’t immediately available.