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Nov/Dec 2000
Vol. 3, No. 9, p. 13.

news in brief

Stem cell survival

red blood cellsThe dream of one day correcting genetic blood diseases before a child is even born may be one step closer to reality, thanks to new stem cell research at the John P. Robarts Research Institute in London, Canada. Researchers there have managed to identify and extract stem cells from living fetuses that could one day be used in gene therapies.

Hematopoietic stem cells are blood factories. Much about these cells remains unknown, but they seem to be long-lived and can produce several different, more specialized cells. In blood formation, they produce short-lived progenitor cells that then give rise to actual blood cells. Because they are long-lived, perhaps even surviving in the bloodstream for a lifetime, stem cells are an obvious target for gene therapy.

The goal is to remove hematopoietic stem cells and introduce healthy versions of missing or malfunctioning genes. The cells could then be reintroduced into the patient to produce healthy blood.

Genetically corrected cells have yet to be used as a treatment, but researchers have isolated stem cells from umbilical cord blood extracted after birth and from aborted fetuses. Unfortunately, these are poor sources of the cells, and the postnatal treatment of infants with their own cells may be too late to prevent serious medical problems. Using cells from aborted fetuses also presents major ethical and immunological problems. The ideal source, then, would be prenatal stem cells from a pro spective patient.

That is exactly the source that the London team, led by Mickie Bhatia, has used. After extracting fetal blood samples via routine procedures, they isolated human hematopoietic stem cells and followed their activity in mice. The cells, which can be gathered from fetuses as young as 12–18 weeks, seem to be more active than those isolated from postnatal cord blood (Blood 2000, 96, 1740–1747).

Bhatia says that the next step will be to start making gene corrections in the cells. If all goes well, they would begin inserting the modified cells in animals and then start looking for suitable patients for human trials. He predicts that actual application of treatments using the newly identified cells could happen within five years.


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