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Unlocking the potential: Ex vivo expansion of cord blood stem cells

by Andrew Shuen, MD PhD


Stem cells under fluorescent 3D microscope

Cord blood, collected from the umbilical cord and placenta after childbirth, is a rich source of hematopoietic stem cells (HSCs) and other progenitor cells. These cells have the unique ability to differentiate into various cell types, making them invaluable for regenerating damaged tissues and treating diseases such as leukemia, lymphoma, and certain genetic disorders.

However, the limited number of stem cells in a single cord blood unit has been a challenge for transplantation in adult patients. Ex vivo expansion aims to overcome this limitation by stimulating the growth and multiplication of cord blood stem cells outside the body before transplantation. This process involves carefully controlling the culture conditions and providing specific growth factors to encourage the expansion of functional stem and progenitor cells.

The potential benefits of ex vivo expansion include:

  1. Increased Cell Numbers: By expanding the number of stem cells, researchers hope to enhance the chances of successful transplantation and improve outcomes for patients, especially in cases where a higher cell dose is required.

  2. Broader Applicability: Ex vivo expansion may broaden the range of patients who can benefit from cord blood transplantation, as it addresses the issue of limited cell numbers, making the therapy more suitable for adults.

  3. Accelerated Engraftment: A higher number of transplanted cells may lead to faster and more robust engraftment, reducing the time for the patient to recover immune function and reducing the risk of infections.

Cryopreservation into Adulthood: Ensuring a Lifelong Reserve

Cryopreservation involves freezing cells at ultra-low temperatures, effectively putting them into a state of suspended animation. This process allows individuals to store their cord blood stem cells for an extended period, potentially into adulthood. The decision to cryopreserve stem cells into adulthood is influenced by several factors:

  1. Advancements in Medical Research: With ongoing advancements in stem cell research and regenerative medicine, the potential applications of cord blood stem cells are continually expanding. Cryopreservation allows individuals to take advantage of future breakthroughs in medical science.

  2. Personalized Medicine: Cryopreserving one's own stem cells provides a personalized and genetically matched resource for potential future treatments. This may be particularly relevant in the context of emerging therapies tailored to an individual's unique genetic makeup.

  3. Insurance Against Age-Related Diseases: As individuals age, the risk of certain diseases and degenerative conditions increases. Cryopreserving cord blood stem cells at a young age acts as a form of biological insurance, offering a reserve of healthy and youthful cells that may be used to address age-related health challenges.

  4. Family Planning: Cryopreservation allows parents to store cord blood stem cells not only for their child but also for potential use by siblings or other family members. This familial approach provides a comprehensive strategy for safeguarding the health of the entire family.


The ex vivo expansion of cord blood stem cells and the cryopreservation of these cells into adulthood represent exciting developments in the field of regenerative medicine. As research progresses and technology advances, these strategies hold the promise of unlocking new possibilities for treating a wide range of diseases and conditions. By investing in the preservation and expansion of cord blood stem cells, individuals are securing their own health for years to come.


Saiyin T, Kirkham AM, Bailey AJM, Shorr R, Pineault N, Maganti HB, Allan DS. Clinical Outcomes of Umbilical Cord Blood Transplantation Using Ex Vivo Expansion: A Systematic Review and Meta-Analysis of Controlled Studies. Transplant Cell Ther. 2023 Feb;29(2):129.e1-129.e9. doi: 10.1016/j.jtct.2022.11.007. Epub 2022 Nov 15. PMID: 36396108.

Zimran E, Papa L, Hoffman R. Ex vivo expansion of hematopoietic stem cells: Finally transitioning from the lab to the clinic. Blood Rev. 2021 Nov;50:100853. doi: 10.1016/j.blre.2021.100853. Epub 2021 Jun 4. PMID: 34112560.

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