Lab-grown red blood cells
Also known as Lab-grown blood, Stem cell-derived red blood cells, Cultured red blood cells, iPSC-derived red blood cells
Lab-grown red blood cells are made from stem cells as a possible future transfusion product. The UK RESTORE trial has completed its final mini-dose transfusions and is closed to recruitment; results are expected in late 2026 or early 2027. Whether manufactured cells survive longer than donated cells is not yet known, and producing enough cells affordably for routine care remains a major challenge.
In plain language
Red blood cells carry oxygen around the body. Donated blood remains the source for routine red-cell transfusions. Researchers are growing red cells from stem cells in the laboratory to investigate whether manufactured cells could help people who need unusually well-matched blood, including some patients with rare blood groups or complex transfusion needs.
The UK RESTORE study compares small doses of lab-grown cells with standard donated cells from the same donor, tracking how long each remains in the circulation. NHSBT says recruitment is closed, and NIHR reported in February 2026 that the final batch had been given to volunteers. Results are expected in late 2026 or early 2027. The trial has not yet shown that lab-grown cells last longer or improve patient care. Its mini-doses are a research step; the cells are not available as a routine blood product.
A central engineering challenge is scale. A normal blood unit contains far more red cells than a mini-dose, and the manufacturing process must reliably mature cells, remove their nuclei, meet clinical quality standards and do so at a cost that can be justified for a particular patient group. The likely early use, if the approach succeeds, would be for selected complex transfusions rather than replacing ordinary blood donation.
Technical explanation
Red cells can be made from haematopoietic progenitor cells or from induced pluripotent stem cells (iPSCs), which are adult cells reprogrammed to an embryonic-like state. The cells are expanded, pushed through erythroid differentiation and must then eject their nuclei (enucleation) to become mature red cells. Enucleation has been a bottleneck. Ju and colleagues (2024) report that hiPSCs have an enucleation rate of 4 to 10%, and Varga and colleagues (2025) report that the reported yields of enucleated cells from earlier protocols have remained below 25%.
Yield is the next constraint. Varga and colleagues report about 4.6 × 10^3 red cells per iPSC in an optimised, feeder-free dynamic culture, with a 40 to 70% enucleation rate. They estimate that about 4.9 × 10^7 iPSCs would be needed for one minitransfusion unit of 1 × 10^11 enucleated cells. That work was carried out on orbital shakers, and the authors describe stirred-tank bioreactors as future work with no data yet. Lim and colleagues (2021) note that a single unit of blood contains 2 × 10^12 enucleated red cells, and that fully defined, xenogeneic-free and GMP-compliant processes are needed for clinical translation.
Cell quality is also still under study. In a small mouse study with three mice per group, iPSC-derived human red cells were cleared at a rate not significantly different from native human cells, and both had gone by 144 hours. The authors note that human red cells normally last about 120 days and describe the faster clearance in mice as a discrepancy. The iPSC-derived cells carry fetal haemoglobin and have higher oxygen affinity than adult red cells. Varga and colleagues also note that leukocyte filters used in current practice show suboptimal filtration efficiency (about 30%).
What the evidence says
Each statement is typed by the strength of its evidence and linked to the source that supports it.
Demonstrated Shown in a published experiment, test or shipping product.
By 7 November 2022, two people had received mini transfusions of lab-grown red blood cells in the RESTORE trial, which is run by NHS Blood and Transplant and the University of Bristol.
Sources: [3] · News item, publication date and participantsThe RESTORE trial gives each volunteer two mini transfusions, at least four months apart: one of standard red cells and one of lab-grown cells from the same donor, to test how long each lasts in the body. The lab-grown dose is about 5 to 10 ml.
Sources: [3] · Trial designVarga and colleagues report about 4.6 × 10^3 red cells per iPSC in an optimised, feeder-free dynamic culture, with a 40 to 70% enucleation rate. This is lab-scale work with five healthy-donor iPSC lines.
Sources: [4] · Abstract and results · medium confidenceIn a small mouse study with three mice per group, iPSC-derived human red cells were cleared at a rate not significantly different from native human red cells, and both were cleared by 144 hours. The authors note that human red cells normally last about 120 days and describe the faster clearance in mice as a discrepancy.
Sources: [4] · In vivo results and Discussion · low confidenceJu and colleagues report that hiPSCs have an enucleation rate of 4 to 10%, that inadequate enucleation is a major barrier to large-scale in vitro production of red cells, and that these products have proven difficult to manufacture on a large scale.
Sources: [6] · Abstract and main text · medium confidenceNIHR BioResource reported on 11 February 2026 that the final batch of lab-grown red cells for RESTORE had been given to volunteers, with results expected in late 2026 or early 2027. The update reports trial progress, not outcomes.
Sources: [1] · Trial updateThe NHSBT trial page describes RESTORE as a phase I randomised crossover study in healthy volunteers and states that recruitment is closed.
Sources: [2] · Summary and study designReported, unverified Stated by a company or team but not independently confirmed.
The trial team reports that the two recipients so far are well and healthy, and that no untoward side effects were reported. No formal safety results have been published in the sources reviewed here.
Sources: [3] · Participants · medium confidenceVarga and colleagues estimate that about 4.9 × 10^7 iPSCs would be needed to make one minitransfusion unit of 1 × 10^11 enucleated red cells. This is an estimate, not a tested manufacturing run.
Sources: [4] · Abstract and Discussion · medium confidenceLim and colleagues state that a single unit of blood contains 2 × 10^12 enucleated red cells, that in vitro production processes could carry a cost of US$15,000 or more per blood unit, and that some estimates report even five times higher. Hospitals acquire donated blood at about US$200 to 300 per unit.
Sources: [5] · Introduction · medium confidenceProposed A design or plan that has not yet been built or tested.
The Varga authors anticipate that stirred-tank bioreactors will significantly reduce variation in production efficiency. The study reports no bioreactor data and describes this as future work.
Sources: [4] · DiscussionLimitations and open problems
- RESTORE is a first-in-human phase I crossover study in healthy volunteers using mini-doses, not a therapeutic-dose trial in patients. It cannot establish safety or effectiveness at routine transfusion scale.
- The trial's central question is how long lab-grown cells survive compared with donor cells. Results remain pending; longer survival and fewer transfusions are hypotheses, not demonstrated benefits.
- Enucleation and maturation are unresolved. Ju and colleagues (2024) call inadequate enucleation a major barrier to large-scale production, and iPSC-derived cells still carry fetal haemoglobin.
- Scale is the main barrier. A single unit of blood contains about 2 × 10^12 enucleated red cells (Lim and colleagues, 2021), and the lab-scale process has not been run in stirred-tank bioreactors.
- No verified cost per manufactured unit was found. The figure of US$15,000 or more per unit comes from a 2021 review that reports it as an estimate, and media costs are high (Varga and colleagues, 2025).
- The authors of the iPSC platform note that microcarriers add system complexity and may need enhanced safety measures before human use.
Possible future uses
Ideas, not predictions. None of these has been demonstrated.
- Long-lasting manufactured red cells could reduce how often some people with regular transfusion needs require donor blood. This is not yet shown.
- Lab-grown blood for patients with rare blood groups, for whom well-matched donor blood is hardest to find.
- A backup supply of red cells for emergency or remote care where donation is difficult. This is a hypothesis only.
Timeline
- 10 Sept 2021Lim and colleagues publish a review of iPSC-derived red cells that cites 2 × 10^12 enucleated red cells in a single unit of blood and cost estimates of US$15,000 or more per manufactured unit. Sources: [5]
- 7 Nov 2022The University of Cambridge reports that two people have been transfused in the RESTORE trial with lab-grown cells, and that a minimum of 10 participants will receive two mini transfusions. Sources: [3]
- 15 May 2024Ju and colleagues review the field and state that it has proven difficult to manufacture iPSC-derived red cells on a large scale. Sources: [6]
- 12 Jul 2025Varga and colleagues report a feeder-free, GMP-compatible iPSC-to-red-cell system with about 4.6 × 10^3 red cells per iPSC and a 40 to 70% enucleation rate. Sources: [4]
- 11 Feb 2026NIHR BioResource reports that the final batch of lab-grown red cells for the RESTORE trial had been produced and given to volunteers; trial results were expected in late 2026 or early 2027. Sources: [1]
Futures this could help bring about
Related breakthroughs
Glossary
- Enucleation
- The step in which a developing red cell ejects its nucleus, becoming the flexible, nucleus-free cell that carries oxygen.
- Induced pluripotent stem cell (iPSC)
- An adult cell, such as a skin cell, that has been reprogrammed to an embryonic-like state so that it can form many cell types.
- Minitransfusion
- A very small transfusion, here about 5 to 10 ml, used to measure how long cells survive in the body.
- Fetal haemoglobin
- The form of haemoglobin found in the foetus and newborn, which binds oxygen more tightly than adult haemoglobin.
Sources
- government report
Final batch of red blood cells produced in RESTORE
NIHR BioResource, 11 Feb 2026. Accessed 22 Oct 2026. - government report
RESTORE: Recovery and survival of stem cell originated red cells
NHS Blood and Transplant Clinical Trials Unit, 2026. Accessed 22 Oct 2026. - university press release
First ever clinical trial of lab-grown red blood cell transfusion
University of Cambridge, 7 Nov 2022. Accessed 21 Oct 2026. - peer reviewed paper
Large-Scale Production of Transfusion-Ready Red Blood Cells From Induced Pluripotent Stem Cells
Eszter Varga, Eelke Brandsma, Brenda E. Juarez-Garza et al.. Advanced Science, 12 Jul 2025. DOI: 10.1002/advs.202504725. Accessed 21 Oct 2026. - review article
Industrially Compatible Transfusable iPSC-Derived RBCs: Progress, Challenges and Prospective Solutions
Zhong Ri Lim, Svetlan Vassilev, Yew Wai Leong et al.. International Journal of Molecular Sciences, 10 Sept 2021. DOI: 10.3390/ijms22189808. Accessed 21 Oct 2026. - review article
Progresses in overcoming the limitations of in vitro erythropoiesis using human induced pluripotent stem cells
Hyeonwoo Ju, Yeowon Sohn, Yoojun Nam et al.. Stem Cell Research & Therapy, 15 May 2024. DOI: 10.1186/s13287-024-03754-9. Accessed 21 Oct 2026.
Revision history
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