Supported by Berkeley Biotech Approach published by Nature Rather than chemically or genetically reprogramming older cells, it recreates the embryonic environment in which blood stem cells first form. Its lead program targets bone marrow transplantation in blood cancers and has received FDA Orphan Drug Designation.
HexemBio opened to the public with a $10.4 million seed round SOSV is managed by Draper Associates with participation from Seraphim and other investors. Based in Berkeley and New York, the company is developing what it describes as the first blood stem cell The rejuvenation therapy is built around a platform called Synthetic Human Yolk.
Instead of editing or chemically reprogramming aged hematopoietic stem cells, this technology temporarily places a patient’s own cells in a recreated version of the growth medium where the blood stem cells first appear in the embryo, then returns them through a standard IV infusion.
Hematopoietic stem cells sit deep in the bone marrow and give rise to every blood and immune cell in the human body. Their decline with age is associated with weakened immunity, chronic inflammation, and increased susceptibility to conditions including blood cancer and neurodegeneration.
Previous attempts to reverse this decline have typically involved transcription factor reprogramming, cytokine therapy or gene editing, approaches that can destabilize cells or carry safety risks, HexemBio says.
The Synthetic Human Yolk Sac recreates the microenvironment that creates the body’s first blood stem cells during early embryonic development. The seminal work supporting the platform was published in the journal Nature in February 2024 by a team led by Mo Ebrahimkhani at the University of Pittsburgh, with Samira Kiani and Joshua Hislop among the authors. All three are now co-founders of HexemBio.
The company’s lead clinical program targets bone marrow transplantation in patients with blood cancers, including acute myeloid leukemia and acute lymphoblastic leukemia.
HexemBio received FDA Orphan Drug Designation for this indication in July 2025 and completed the FDA Pre-IND meeting in January 2026. The first human trials are scheduled for 2027.
The regulatory strategy focuses on bone marrow transplant outcomes because aging itself is not currently recognized as a regulatory indicator, a limitation that has shaped how several longevity-adjacent biotechs have structured their early clinical programs.
The founding team consists of MIT, UC Berkeley, Harvard and Y Combinator. Gabriel Levesque Tremblay, former YC founder and UC Berkeley postdoc, serves as CEO. MIT-educated Presidential Early Career Award winner Samira Kiani is the CTO.
Mo Ebrahimkhani, an inventor of the underlying technology and a pioneer in synthetic developmental biology, is CSO. Joshua Hislop, whose doctoral work contributed directly to Nature, leads the company’s AI platform, which includes proprietary tools YolkGPT and YolkScore. Samet Yıldırım, a former YC founder with experience in drug development at Boehringer Ingelheim, is the chief business officer.
The advisory board includes Robert S. Langer, Institute Professor at MIT and co-founder of Moderna.fundamentally different from transcription factor reprogramming or gene editing, and he said the early data were ‘extremely compelling’.
Additional advisors include Peter Barton Hutt, former FDA general counsel and current Moderna board member; Joanne Kurtzberg of Duke University, one of the leading bone marrow transplant clinicians in the United States; David Harris, founder of the first public cord blood bank in the United States; Felipe Sierra, former director of NIH’s Division of Biology of Aging; Jens Nielsen, CEO of BioInnovation Institute; and George Church, professor of genetics at Harvard Medical School and co-founder of Colossal Biosciences.
Seed funding will be used to complete IND-enabling research and GMP manufacturing ahead of the 2027 trial target.
