Exosomes and Stem Cells...
Rehovot, Israel –
It is known that exosomes, small, viral-sized particles are used by the immune system to communicate with itself.
In a recent paper published by Lapidot’s group (Kalinkovich et al. Functional CXCR4-expressing microparticles and SDF-1 correlate with circulating acute myelogenous leukemia cells. Cancer Res. 2006 Nov 15;66(22):11013-20) circulating exosome-like particles that possess CXCR-4 are found in high concentrations in the blood of patients with leukemia. The importance of CXCR-4 is that this is the receptor on stem cells that allows them to follow the SDF-1 gradient so as to home into bone marrow or injured tissue.
SDF-1 is constitutively expressed by the bone marrow stroma, and its expression is induced in injured tissue. Mice that lack SDF-1 do not have bone marrow-mediated cardiac repair after induction of experimental infarcts. Stem cells that lack CXCR-4 do not home to injured tissue either.
The importance of this paper is that CXCR-4 microvesicles can actually enhance the rate of migration of cells to SDF-1 gradients. Therefore an interesting therapeutic possibility which needs to be tested is whether SDF-1 expressing microvesicles can be artificially generated and used to enhance migration of stem cells to where they are suppose to go. On the flip side, one wonders whether the CXCR-4 exosomes actually bind to T regulatory cells and accelerates their migration to tumor sites in cancer patients.
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notch1 said...
that's very interesting!
it's known that exosomes particleas produced by dendritic cells and this is important to anti-cancer immune response.
Some groups were isolated exosome and trying use them itself for anti-cancer treatment. Probably one or 2 companies trying to commercialized this technology and probably they gor some patents.
The new and exciting thing is a link between exosume and HSC by CXCR4-SDF1 traffic axis.