Posted on 09/02/2006 10:07:31 PM PDT by Coleus
In a remarkable feat of stem-cell biology, Australian and Canadian researchers have identified a type of mammary stem cell capable of reconstituting an entire mammary gland. Their report appears in the January 5 issue of Nature.
Stem cells reside within many different tissues and share two essential characteristics. First, they can give rise to progeny capable of differentiating into mature, specialized cells appropriate for their particular tissue. Often a single stem cell can ultimately produce several different types of mature cells. Second, stem cells are self-renewing, meaning that when they proliferate, they also produce more stem cells. There is considerable interest in their potential use to replace diseased tissues.
The mammary gland consists of a complex, branching epithelial "tree" which produces milk and funnels it through a network of ducts, embedded in a fat pad. The expansion of this tree during puberty, and through multiple rounds of pregnancy, suggests the existence of mammary stem cells (MaSCs). In the new study, researchers sought to purify MaSCs by harvesting mouse mammary tissue and sorting the cells according to the presence of specific proteins on the cell surface. They transplanted subsets of the sorted cells back into mouse mammary glands from which the epithelial network had been removed, leaving only the fat pad. The presence of MaSCs could be inferred from regrowth of the epithelial tree.
The authors first removed cells that expressed proteins associated with red or white blood cells or blood vessel walls. Next, they identified a population of cells that expressed proteins found on skin and neural stem cells, reasoning that these might be markers of stem cells in general. They found that the resulting pool contained a much higher proportion of MaSCs, since a complete gland could be regenerated after transplantation of only a few cells. Carrying these studies to their logical limit, they visualized and transplanted individual cells, and were able in some cases to reconstitute an entire gland from a single MaSC. The reconstituted glands secreted milk when the recipient gave birth, demonstrating that the new glands were functional. Moreover, MaSCs could be recovered from regenerated glands and transplanted successfully to new recipients a second or even third time, arguing that the MaSCs were self-renewing.
In a final set of studies, the authors examined a strain of mice prone to developing breast tumors and found that they contained a higher than normal number of MaSCs. This finding suggests, but does not prove, that MaSCs may be implicated in the development of breast cancer. Further clinical relevance of MaSCs could come from their potential to regenerate mammary tissue following breast cancer surgery.
If this wasn't so serious a subject, I would have demanded pics.
This has cosmetic surgery implications.
I hope it works. A cousin of mine had breast surgery.
It's not an easy thing for a woman.
Pictures!!!
I don't think so. It's not the mammary glandular structure itself that gives the human breast shape; it's the surrounding padding of fat and the underlayment of muscle. Nonlactating mammary glands are actually quite small. When you are admiring a nice pair you're actually admiring a wad of fat held in place with ligaments and connective tissue. There's nothing to indicate that this discovery will influence the way that fat is distributed and suspended.
Please FreepMail me if you want on or off my Pro-Life Ping List.
Allright, then stem cells for the surrounding fat as well. There is definitely a market for it, and the market ultimately gets want it wants.
bump & a ping
Q: How do you make 6 pounds of fat look good?
A: Put a nipple on it.
(Highlight the space [above] after the "A:" for the answer.)
That is really cool.
Easy. Just make the font color=white.
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