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Biotech / Medical : Stem Cell Research -- Ignore unavailable to you. Want to Upgrade?


To: SnowShredder who wrote (39)5/9/2004 7:02:05 AM
From: SnowShredder  Read Replies (1) | Respond to of 495
 
Insulin Cells Are Self-Renewing, U.S. Study Finds

Wed May 5, 6:11 PM ET Add Science - Reuters to My Yahoo!


By Maggie Fox, Health and Science Correspondent

WASHINGTON (Reuters) - The cells in the pancreas that make insulin can create copies of themselves, a finding that shows potential new ways to treat juvenile or type-1 diabetes, U.S. researchers said on Wednesday.



The research, published in this week's journal Nature, also boosts arguments that controversial research using embryonic stem cells may be the best way to pursue a cure for the disease, experts said.

Dr. Douglas Melton of Harvard University and the Howard Hughes Medical Institute and colleagues found the self-renewing pancreatic cells in mice.

These cells, called beta cells, make insulin. But in type-1 diabetes, which affects between 1 million and 2 million people in the United States alone, the immune system mistakenly destroys these cells.

Patients must inject themselves with insulin daily to stay alive, and they risk blindness, limb loss and stroke.

Scientists are working to find new sources of these cells. But there are not enough donors for transplants.

Another potential source is master cells called stem cells, which give rise to new cells. So-called adult stem cells exist in various tissues and blood but have not been found in the pancreas.

Then there are embryonic stem cells. These cells have the ability to produce cells that make any kind of tissue at all, and the hope is to train them to produce tissues and organs on demand.

But their origin is controversial to some people, because they are taken from tiny embryos left over from IVF or test tube fertilization attempts. They can also be made using cloning technology.

Opponents, including President Bush (news - web sites) and some members of the U.S. Congress, find both approaches ethically unacceptable, although there is wider acceptance of the use of IVF embryos.

A SEARCH FOR EVIDENCE

Melton and colleagues looked for evidence of adult stem cells in the pancreases of the mice.

They gave the cancer drug tamoxifen to the mice, using it as a tracer in cells. It persists in the mature beta cells.

All the new beta cells they could find contained tamoxifen, showing they were generated from preexisting beta cells, Melton reported.

"If ... people have residual beta cells, these findings suggest that a useful clinical direction would be to find a way to boost the proliferative capacity of those beta cells, to restore insulin production in such patients," Melton said in a statement.

"On the other hand, if type 1 diabetics don't have any beta cells left, then these findings suggest that the only source of new beta cells is probably going to be embryonic stem cells, because there don't appear to be adult stem cells involved in regeneration."

Dr. Ken Zaret of the Fox Chase Cancer Center in Philadelphia said the study did not prove there are no adult stem cells in the pancreas. "But it does shine light on a resource for insulin-producing cells that has been there all along: the beta-cell itself," Zaret wrote in a commentary.



Dr. Robert Goldstein of the Juvenile Diabetes Research Foundation said the study supported his organization's argument that the federal government should lift restrictions on funding embryonic stem cell research.

"Some people say you don't need embryonic stem cells because adult stem cells do everything. This would suggest that is not correct," Goldstein said in a telephone interview.

His organization is offering funding to researchers who want to find out if beta cells can regenerate themselves.


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To: SnowShredder who wrote (39)6/21/2004 10:56:56 AM
From: SnowShredder  Read Replies (2) | Respond to of 495
 
Spontaneous cardiomyocyte differentiation from adipose tissue stroma cells.

Planat-Benard V, Menard C, Andre M, Puceat M, Perez A, Garcia-Verdugo JM, Penicaud L, Casteilla L.

UMR 5018 UPS CNRS, IFR31, Research Institute 31, France.

Cardiomyocyte regeneration is limited in adult life. Thus, the identification of a putative source of cardiomyocyte progenitors is of great interest to provide a usable model in vitro and new perspective in regenerative therapy. As adipose tissues were recently demonstrated to contain pluripotent stem cells, the emergence of cardiomyocyte phenotype from adipose-derived cells was investigated. We demonstrated that rare beating cells with cardiomyocyte features could be identified after culture of adipose stroma cells without addition of 5-azacytidine. The cardiomyocyte phenotype was first identified by morphological observation, confirmed with expression of specific cardiac markers, immunocytochemistry staining, and ultrastructural analysis, revealing the presence of ventricle- and atrial-like cells. Electrophysiological studies performed on early culture revealed a pacemaker activity of the cells. Finally, functional studies showed that adrenergic agonist stimulated the beating rate whereas cholinergic agonist decreased it. Taken together, this study demonstrated that functional cardiomyocyte-like cells could be directly obtained from adipose tissue. According to the large amount of this tissue in adult mammal, it could represent a useful source of cardiomyocyte progenitors.

PMID: 14656930 [PubMed - indexed for MEDLINE]

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