Stem Cells Cultured in Human In Vitro System

A recent study describes the use of human marrow stromal cells to replace mouse embryonic fibroblasts as feeder cells for the in vitro cultivation of human embryonic stem cells. The study appeared in the March 2003 issue of Stem Cells.

Investigators at Johns Hopkins University (Baltimore, MD, USA) have been seeking alternative methods for maintaining cultures of primitive, undifferentiated human embryonic stem cells in order to avoid use of growth factors of rodent origin. They used culture-expanded human marrow stromal cells from multiple donors as feeder cells to support growth of a human embryonic stem cell line under serum-free culture conditions. Stem cell colonies cultured on irradiated stromal cells amplified more than 100-fold during 30 days of continuous culture (in five passages). The longest continuous expansion of stem cells on stromal cells tested to date was 13 passages.

"After eight months of dividing under these conditions, the human embryonic stem cells still look and act just like the originals,” explained first author Dr. Linzhao Cheng, assistant professor of oncology at the Johns Hopkins University's Kimmel Cancer Center. "Marrow stromal cells co-exist cells with blood-forming stem cells in bone marrow and support their growth in the lab, but we were surprised they could fully replace mouse cells in supporting more primitive embryonic stem cells. When it is time to create new stem cell lines, this issue will be very important. Our results together with those of others show that it should be possible to establish new stem cell lines without using mouse cells or proteins.”



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