A way of dramatically multiplying the number of primitive stem cells in samples of human umbilical cord blood has been developed by a US team.
Until now the stem cells from one cord have only been sufficient to treat one child with leukaemia. But the new technique promises to create enough cells to treat adult sufferers as well.
鈥淭his demonstration is a significant step towards possibly expanding the use of this source of blood stem cells for treatment of an adult,鈥� says Ken Campbell of the UK鈥檚 Leukaemia Research Fund.
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However, some researchers warn it is as yet unclear whether multiplying these cells at an early stage might diminish their capacity for self-renewal later. If this happened, the transplanted cells might be a source of new blood cells for only a limited period.
Irwin Bernstein at the Fred Hutchinson Cancer Research Center in Seattle, US, who led the work, thinks transplanting a portion of untreated blood along with a portion containing multiplied cells might avoid this potential problem.
Wipe out
Treatment for leukaemia and some other blood disorders often involves wiping out the patient鈥檚 faulty source of blood and immune cells, then transplanting bone marrow to act as a new healthy source of the cells. But bone marrow is in short supply.
However, blood from umbilical cords is a promising alternative, as it is also rich in the haematopoietic stem cells that can develop into any type of blood cell. Stem cells from umbilical cord blood also develop faster than those in bone marrow, and are much less likely to trigger an immune rejection response in a recipient.
The experimental treatment has been successful in a small number of children with leukaemia, but adults need many more cells. And previous work suggests that pooling umbilical cord stem cell populations from different donors does not work well. 鈥淚t is being tried but it seems that only one stem cell population starts to replenish the cells,鈥� Bernstein says.
Hundredfold increase
Bernstein鈥檚 team exposed human stem cells to a molecule called Delta-1, and found a hundredfold increase in the most primitive type of blood stem cell. Delta-1 permanently switched on a signal directing the stem cells to self-renew.
Bernstein鈥檚 team then transplanted the multiplied cells into mice models of leukaemia sufferers. The cells went on to successfully replenish the blood with red and white cells.
鈥淪tudies suggest that multiplying the number of cells from one cord just by two or three times could be enough to treat an adult. If safety and efficacy trials go well, we鈥檇 hope to start trying the approach in two to three years,鈥� Bernstein told 麻豆传媒.
Journal reference: Journal of Clinical Investigation (vol 110, p 1165)