Human embryonic stem cells (hESCs) are valued for their potential to turn into most cell types of the body. With continuing research, they hold strong promise in the field of cell and tissue engineering.
Human ESCs are cultured, or grown, on primary mouse embryonic fibroblast feeder (PMEF) cells in the lab. However since PMEFs are not of the same species as the human cells, they may transmit pathogens to the hESCs, limiting their ability to be transplanted for medical purposes in the future.
Although many types of human cells have been tested as feeder layers for hESC cells, they do not support the hESC culture as well as the mouse cells.
Recently, Michael Shamblott, an assistant professor in the Department of Gynecology and Obstetrics at the Hopkins School of Medicine, and his colleagues were able to successfully culture hESC cell lines on tissue isolated from human umbilical cord blood (UCB).
Fibroblast cells from UCB can be easily harvested after birth from the placenta without posing harm to an infant.
"Feeder layers are used to support embryonic stem cells," Shamblott said. "The goal is to keep stem cells from differentiating. How they do that is still largely a mystery."
Shamblott's team showed that the hESCs cultured in this novel feeder layer are still able to successfully differentiate after the feeder layer is removed.
Embryoid bodies are microscopic structures formed as embryonic stem cells differentiate. These bodies are markers of successful differentiation. "We show a new way of creating feeder layers that grow hESCs for a long period of time, and they can still make embryoid bodies."
The most important feature of this novel feeder layer for hESCs are the clinical applications this new discovery portends, especially in the development of cell therapy for diseases.
"There are vast depositories of umbilical cord around the world, and they have been processed in a way that is very safe for cancer and disease therapy," Shamblott said. "In the future, when we develop cell therapy for diseases, we want to ensure the type of cells we use is safe."
This new method of stem cell production offers scientists a great deal of versatility in clinical applications. "You can find an immunological match of umbilical blood to your patient and develop a custom hESCs feeder layer."
In addition, hESCs grow differently on UCB-derived feeder layers than in PMEF feeder cells and can be conveniently lifted off the new UCB-derived feeder layer, making them prime candidates for large-scale production of hESCs for therapeutic applications.
Shamblott hopes that the promise of this new method will promote the use of umbilical blood for therapeutic purposes and prevent this valuable resource from going to waste.
"In this country, human umbilical blood is often discarded as waste, when they could potentially save the lives, since there is no unified system for their collection," Shamblott said. "When umbilical blood is harvested from the placenta there is no risk involved from either the mother or the fetus."
