Why is the correct storage of stem cells so important for the future of medical innovation?
Stem cells can be sourced from the bone marrow itself, peripheral blood and, more recently, umbilical cord blood. Stem cells from umbilical cord blood (haematopoietic stem cells) have to date been used to repair bone marrow in more than 2000 patients. In the US, cord blood has become the most frequent source of stem cells for transplantation in children. Along with ongoing research to improve the use of cord blood in stem cell transplants, a significant amount of research is being conducted to explore the application of cord blood in the field of regenerative medicine. Currently, there are ongoing clinical studies investigating the value of cord blood in the treatment of brain injury, cerebral palsy, Type 1 diabetes, heart disease and critical limb ischaemic.The market for stem cells is very much in its infancy, but there is little doubt that stem cell storage will be the norm in years to come, not just in the private sector, but also for public health services and other public arenas.
New sources of stem cells from adipose tissue (fat), children's milk teeth and even hair are regularly being identified and stored under cryogenic conditions that preserve materials unaltered; this usually involves temperatures from 160 ºC to 190 ºC. Liquid nitrogen is the most logical choice for storage at temperatures below 130 ºC, but there are risks associated with its use. The extremely low temperature of the liquid can cause severe burnlike damage to the skin either by contact with the fluid, surfaces cooled by the fluid or evolving gases. Large volumes of nitrogen gas are evolved from small volumes of liquid nitrogen. This can easily replace normal air in poorly ventilated areas leading to the danger of asphyxiation. The risk of injury is moderate, with cryogenic burns the most likely injury; however in exceptional circumstances when large amounts of material are spilled in an enclosed space, asphyxiation may be fatal.
To ensure there is no crosscontamination with the stored samples, it is generally recommended that materials are accommodated in the vapour phase above the actual nitrogen, where temperatures are in the region of 150 ºC down to 197 ºC. Crosscontamination of biological samples when immersed in the liquid nitrogen may mean viruses and bacteria can invade the stored samples.
Industry experts believe that the use of drystore freezers, specifically designed as vapour phase storage systems, offer exceptional sample security; a slight positive pressure in the sample chamber will circulate out any pathogens; and operator safety is ensured as the storage area is completely free of liquid nitrogen, which is housed in a jacket surrounding the chamber. Temperature performance to 190 °C can be achieved well below the level required to keep materials in firstclass condition.
By storing stem cells taken from a baby's umbilical cord, it is now possible for parents to insure their child's future health against diseases such as cancer, diabetes, cardiovascular problems and blood disorders.