Cord blood is the blood that remains in the umbilical cord and placenta following childbirth. It is a rich source of hematopoietic stem cells, which are unique cells capable of developing into various types of blood cells. These cells are valuable for their regenerative properties and potential to treat certain diseases. The collection of cord blood is a simple, non-invasive procedure performed after the baby is born and the umbilical cord has been clamped and cut.
The Science of Cord Blood Preservation
The long-term preservation of cord blood relies on a process called cryopreservation. This technique involves carefully freezing the cells at extremely low temperatures, typically in liquid nitrogen, reaching temperatures below -150 degrees Celsius. Maintaining these ultra-low temperatures effectively halts all cellular activity and metabolic processes. This cessation of biological functions prevents cell degradation over extended periods.
Before freezing, cryoprotectants are introduced to the cord blood sample. These specialized substances, such as dimethyl sulfoxide (DMSO), protect the cells from damage during freezing and thawing. Cryoprotectants work by reducing the formation of ice crystals, which can puncture cell membranes and render the cells non-viable. The careful control of cooling rates during freezing further minimizes cellular stress and maximizes the recovery of viable cells upon thawing.
How Long Can Cord Blood Be Stored?
Scientific evidence indicates that properly cryopreserved cord blood can be stored for decades while maintaining its viability. Research by Dr. Hal Broxmeyer’s laboratory, a pioneer in cord blood preservation, demonstrated that cryopreserved cord blood remained viable after 27 years in frozen storage. This work has been replicated by other laboratories globally, including facilities in Florida, South Korea, and Germany. These findings suggest that when cord blood is stored under optimal conditions, it does not appear to age.
Real-world applications also support these long-term storage capabilities. In 2018, a public cord blood bank in Australia successfully used a 20-year-old donor cord blood unit to treat a leukemia patient. More recently, in May 2023, a young adult in China was reportedly cured of aplastic anemia using their own cord blood that had been stored for 19 years. While a definitive “expiry date” has not been established, accumulating evidence from laboratory studies and successful clinical transplants indicates stability over many years. The longevity of a specific sample also depends on its initial quality and the consistent maintenance of the ultra-low storage temperatures.
Ensuring Viability and Quality Over Time
Maintaining the viability and quality of cord blood throughout its storage period involves rigorous measures. After collection, the cord blood undergoes initial processing, which includes assessing the total cell count and testing cell viability to ensure the sample meets established standards. This initial quality assessment helps determine the sample’s suitability for long-term storage.
Proper freezing protocols are followed to prepare the sample for cryopreservation, using controlled-rate freezers to gradually lower the temperature. Throughout the storage duration, reputable facilities continuously monitor cryogenic storage temperatures to prevent fluctuations that could compromise cell integrity. Periodic quality checks are also performed on representative samples to confirm cells remain functional and suitable for potential therapeutic use.
Applications of Stored Cord Blood
Stored cord blood serves primarily for hematopoietic stem cell transplantation. These stem cells treat a range of diseases affecting the blood and immune system. Conditions such as leukemias, lymphomas, certain anemias, and inherited metabolic disorders can benefit from healthy stem cell transplantation using cord blood.
The unique properties of cord blood stem cells, including their lower risk of graft-versus-host disease compared to adult bone marrow stem cells, make them a suitable option for transplantation. Beyond current therapeutic applications, cord blood also holds promise in regenerative medicine research. Scientists are exploring its potential for repairing damaged tissues and organs, and for developing new treatments for various medical conditions.