T细胞的免疫反应水平决定干细胞的再生能力

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老狼以为干细胞移植受体存在一个“机会窗口”问题——炎症反应是决定细胞植入的关键，下面文章认为干扰素γ和肿瘤坏死因子α表达水平影响干细胞对组织的修复作用。
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0 R9 Z1 `& a! e! ^( MRecipient's Immune System Governs Stem Cell Regeneration  B- ^# a/ w8 N1 |+ a0 G. h
ScienceDaily (Nov. 20, 2011) — A new study in Nature Medicine describes how different types of immune system T-cells alternately discourage and encourage stem cells to regrow bone and tissue, bringing into sharp focus the importance of the transplant recipient's immune system in stem cell-based regeneration.
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% y# p) h" z0 J7 x4 T8 z6 E( YThe study, conducted at the Center for Craniofacial Molecular Biology at the Ostrow School of Dentistry of USC, examined how mice with bone defects responded to bone marrow mesenchymal stem cell (BMMSC)-mediated bone regeneration.+ R3 i( U) g% E, c! t) i: L

) x6 r  G/ O8 h6 G0 m+ c# P! X& L2 ?Under normal conditions, the mice's T-cells produced an inflammatory response and triggered the creation of cytokines interferon (INF)-gamma and tumor necrosis factor (TNF)-alpha. These attacked and killed the stem cells, preventing the production of new bone.
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"Normally, T-cells protect us from infection," said Professor Songtao Shi, corresponding author for the study, "but they can block healthy regeneration from happening."; u- L+ ~7 ^* y  l

8 k& u8 X& Q, b6 \1 t3 Z! s/ SHowever, when the mice were given infusions of regulatory T-cells (Tregs), the levels of the interfering INF-gamma and TNF-alpha decreased, increasing the rate of bone regrowth and defect repair. Furthermore, administering the anti-inflammatory drug aspirin at the site of the bone defect also increased the rate at which the BMMSCs were able to regrow bone.
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3 g7 d; F& m4 H5 T( h6 g, IPostdoctoral Research Associate and lead author Yi Liu said the findings illustrate the previously unrecognized role of T-cells in tissue regeneration. They also highlight the need for scientists exploring the possibilities of stem cell-based regeneration to shift their focus to the immune system, she added.
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' [, g6 O' j: r3 R9 p& W5 b; }"Based on what we've found, this should be the direction of more research in the future," Liu said.
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http://www.sciencedaily.com/releases/2011/11/111120134749.htm8 {  c& P: T% N1 ?, u- E- y& i2 S