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本帖最后由 naturalkillerce 于 2011-10-10 00:02 编辑 5 G. w* [) }6 @4 M/ g) r5 B! N7 w
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Diabetic rats cured with their own stem cells
! A+ d) M! R3 U3 ~00:01 07 October 2011 by Andy Coghlan
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9 V2 f6 o9 P' W$ U4 F) |For similar stories, visit the Stem Cells Topic Guide( q4 q5 n( A5 Z+ x. }8 A
A cure for diabetes could be sitting in our brains. Neural stem cells, extracted from rats via the nose, have been turned into pancreatic cells that can manufacture insulin to treat diabetes.0 Y- z1 A" F3 M0 ~3 e5 Y g
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Beta cells in the pancreas produce insulin, which regulates glucose levels. People with diabetes either have type 1, in which native beta cells are destroyed by the immune system, or type 2, in which beta cells cannot produce enough insulin.* p8 T. Z8 v. \ C3 Q D# e) |
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To replace lost or malfunctioning beta cells, Tomoko Kuwabara of the National Institute of Advanced Industrial Science and Technology in Tsukuba Science City, Japan, and colleagues turned to neural stem cells in the brain.: v, f; p8 A2 r! ~
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Nasal extraction. Z! _( [$ }& {! \- i
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First, they extracted a tiny amount of tissue from the rats' olfactory bulb, the part of the brain which deals with smell, or from the hippocampus, involved in memory. Each area is accessible through the nose, both in rats and humans.6 S; j7 C3 l) n4 N, N: z
- ^8 R8 N+ P4 c& P' `6 X$ _Next, the team extracted neural stem cells from the tissue and exposed them to Wnt3a – a human protein that switches on insulin production – and to an antibody that blocks a natural inhibitor of insulin production.
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After multiplying the stem cells for two weeks, they placed them on thin sheets of collagen which act as a removable scaffold. This allowed the team to lay the sheets incorporating the cells on top of the rats' pancreas without harming the organ itself.8 p$ |3 _$ V {) j6 b. W
' F3 k' f% M# T5 Y( D7 L5 h: ]6 ]Within a week, concentrations of insulin in the blood of both type 1 and type 2 rats that had received treatment matched those in non-diabetic rats. Elevated blood glucose concentrations also returned to normal.4 ~0 P4 n! p- u8 k6 z
0 H w7 x# `" D( E+ c/ UThe cells successfully tackled diabetes for 19 weeks until researchers halted the treatment by removing the sheets of cells, after which the rats' diabetes returned.+ z7 ^$ k. w5 b- @ \0 z
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Natural change0 Q, L; `, O, U9 B
/ D+ @! H2 F; l, B) {( NCrucially, the cells did not have to be genetically manipulated outside of the body.
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; T6 K9 I' V! f* kMany other labs around the world have tried altering stem cells from other parts of the body, including the gut, the liver and blood, to change them into beta cells. But these all require alterations or genetic manipulations which could pose safety concerns when transferring the treatment to humans.
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Because the cells in the current study come from the same animal in which they are transplanted, they also overcome hurdles of rejection or the need for immunosuppressive drugs, such is the case when people receive donor pancreatic cells.
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No manipulation
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The researchers believe that it would be safe to access neural stem cells in humans. "It would be possible to extract adult neural stem cells from the olfactory bulb surgically using an endoscope," they say, adding that other groups have already done such extractions, proving that they are practical.
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"The most important improvement offered by this study is the derivation of insulin-expressing cells from diabetes patients without the need for genetic manipulation," say Onur Basak and Hans Clevers of the Hubrecht Institute for Development Biology and Stem Cell Research in Utrecht, the Netherlands, in a commentary published alongside the work (EMBO Molecular Medicine, DOI: 10.1002/emmm.201100178).* U4 i, e7 G0 D3 F6 e
2 t5 ^1 O7 @ S8 V! M. g2 O% Y"It will be essential to validate these results in available human neuronal stem cell lines as well as patient-derived olfactory bulb neural stem cells," they add.
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Journal reference: EMBO Molecular Medicine, DOI: 10.1002/emmm.2011001771 G- R1 \( }) ~* T1 ~
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http://www.newscientist.com/arti ... own-stem-cells.html |
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发表于 2011-10-9 23:40
