A one-hour protein treatment could supercharge blood stem cell transplants

Blood stem cells are the body's lifelong supply chain for blood and immune cells — but when they're processed in the lab for gene therapy or bone marrow transplants, they often lose some of their regenerative punch. Now, researchers at the University of Zurich's Institute for Regenerative Medicine (IREM) think they've found a fix.

The team studied how a protein called activated protein C (aPC) affects human blood stem cells. Although aPC and another clotting protein, thrombin, both activate the same cell receptor (PAR1), they produce strikingly different results. aPC kept stem cells in a calm, "quiescent" state — dividing less, differentiating less, and staying more potent — while thrombin pushed cells toward premature specialization, reducing their stem cell capacity.

Crucially, just one hour of aPC treatment was enough to improve how well human blood stem cells engrafted and sustained blood formation after transplantation into mice, even through repeated rounds.

Key Takeaways:

• aPC preserves stem cell quiescence by acting through the PAR1 receptor — the same receptor that thrombin activates, but with opposite effects
• A short aPC pre-treatment of just one hour significantly improved engraftment and long-term blood production in animal models
• aPC also shielded stem cells from inflammatory signals that would otherwise disrupt their resting state

Why it matters: Better-preserved stem cells mean more effective transplants and gene therapies for patients with blood disorders — potentially improving treatment success with a simple pre-treatment step.