Marrow is Less Fixed and More Flexible than Thought

[Guest guest]

Rockefeller University Press

Unappreciated dynamism of blood cell production

The bone marrow stem cells responsible for generating new blood cells are less

fixed and more flexible than previously thought, according to a paper published

online on February 7 in the Journal of Experimental Medicine (www.jem.org).

Some earlier studies suggested that these hematopoietic stem cells (HSCs) come

in two distinct varieties: those that remain dormant during times of health but

possess the ability to regenerate the whole blood system after trauma such as

irradiation or chemotherapy, and those that divide frequently and contribute to

new blood production during times of health but lack the capability of restoring

the whole blood system after trauma.

Using a new technique to label and track mouse HSCs, Markus Manz and colleagues

find that at any given time, cells harboring the capacity to restore a wiped-out

blood system can actually be found in both rapidly dividing and dormant HSC

populations. In fact, with age, HSCs tend to shift status from rapidly dividing

to dormant. Yet upon encounter with life-threatening bacteria, dormant HSCs

quickly awake, divide and replicate themselves.

These findings suggest that the burden of blood cell production may be more

equally shared than previously realized among all HSCs. Whether human HSCs

exhibit similar on-demand adaptability remains to be determined.

###

The Journal of Experimental Medicine

news@...

212-327-8603

Rockefeller University Press

Unappreciated dynamism of blood cell production

The bone marrow stem cells responsible for generating new blood cells are less

fixed and more flexible than previously thought, according to a paper published

online on February 7 in the Journal of Experimental Medicine (www.jem.org).

Some earlier studies suggested that these hematopoietic stem cells (HSCs) come

in two distinct varieties: those that remain dormant during times of health but

possess the ability to regenerate the whole blood system after trauma such as

irradiation or chemotherapy, and those that divide frequently and contribute to

new blood production during times of health but lack the capability of restoring

the whole blood system after trauma.

Using a new technique to label and track mouse HSCs, Markus Manz and colleagues

find that at any given time, cells harboring the capacity to restore a wiped-out

blood system can actually be found in both rapidly dividing and dormant HSC

populations. In fact, with age, HSCs tend to shift status from rapidly dividing

to dormant. Yet upon encounter with life-threatening bacteria, dormant HSCs

quickly awake, divide and replicate themselves.

These findings suggest that the burden of blood cell production may be more

equally shared than previously realized among all HSCs. Whether human HSCs

exhibit similar on-demand adaptability remains to be determined.

###

About The Journal of Experimental Medicine

news@...