Wednesday, February 13, 2008
Plucking Cells out of the Bloodstream
A new implantable device can extract stem cells for therapeutic transplant or program cancer cells to die.
By Katherine Bourzac

To read the entire article, go to this link:
Technology Review: Plucking Cells out of the Bloodstream

Bioengineers have developed an implantable device that captures very pure samples of stem cells circulating in the blood. The device, a length of plastic tubing coated with proteins, could lead to better bone-marrow transplants and stem-cell therapies, and it also shows promise as a way to capture and reprogram cancer cells roaming the bloodstream. The company CellTraffix is commercializing the technology.

When patients get bone-marrow transplants, what they're really receiving are infusions of a type of adult stem cell. Bone-marrow-derived stem cells play a crucial role in renewing the blood throughout adulthood, creating new cells to carry oxygen and fight infections. These adult stem cells can be sampled using the new device.

The new device mimics a small blood vessel: it's a plastic tube a few hundred micrometers in diameter that's coated with proteins called selectins. The purpose of selectins in the body seems to be to slow down a few types of cells so that they can receive other chemical signals. A white blood cell, for instance, might be instructed to leave the circulation and enter a wound, where it would protect against infection. "Selectins cause [some] cells to stick and slow down," says Michael King, a chemical engineer at the University of Rochester who's developing the cell-capture devices. Different types of selectins associate with different kinds of cells, including platelets, bone-marrow-derived stem cells, and immune cells such as white cells.

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