圖片來源：www.proglyta.com
2016年2月1日 訊 /生物谷BIOON/ --一直以來，科學家們對巨噬細胞的起源存在一定誤解，巨噬細胞作為一種白細胞在機體發育和免疫力上扮演著重要角色，近日來自新加坡A*STAR的科學家們利用一種新型技術證明了，在早期胚胎發育期間成體組織中的巨噬細胞有兩種來源。
巨噬細胞是人體包括大腦、肺部和腸道在內主要器官的重要組分，其可以「巡視」機體中的病原體，幫助誘發防禦機制並且吞食掉損傷的細胞；巨噬細胞同樣還可以抵禦多種疾病的發生，並且參與了多種癌症的發生過程，因此根據必要的反應，新型療法就會限制或者增強巨噬細胞的活性。
截止到2010年，科學家們都認為所有的巨噬細胞都會通過單核細胞的持續供給來進行補充，單核細胞是另外一種白細胞，隨後研究者就通過研究發現，位於大腦中的小神經膠質細胞實際上是來自於胚胎中的卵黃囊巨噬細胞。研究者Ginhoux說道，基於以上研究結果我們就提出了關於胚胎中巨噬細胞發育的一種系統性見解，而且我們還利用一種「預測命運圖譜」來對祖細胞進行標記並且追蹤其在成年各個階段的行為。
研究者對小鼠模型進行研究，對小鼠的胚胎巨噬細胞祖細胞進行了標記，當進行注射後巨噬細胞祖細胞就會釋放螢光，這就可以幫助研究者根據細胞的運動和分化來對其進行追蹤研究。研究者指出，這項研究就可以幫助我們證實卵黃囊巨噬細胞和胚胎單核細胞是來自早期和晚期的祖細胞；卵黃囊巨噬細胞可以產生小膠質細胞，同時胚胎單核細胞則會在其分化成為成體組織的巨噬細胞之前在其它組織中定植，隨後巨噬細胞就會進行自我更新。
下一步研究者將會通過深入研究來回答是否巨噬細胞的起源非常重要，從本質上來講這是一場「先天和後天」的爭辯，即是否巨噬細胞的起源會影響到晚期發育階段，甚至是正常情況和疾病狀況下細胞的功能和行為呢？而更加深入細緻的研究或許對於研究癌症起源和發展也至關重要。（生物谷Bioon.com）
本文系生物谷原創編譯整理，歡迎轉載！點擊 獲取授權 。更多資訊請下載生物谷APP.
Fate Mapping Analysis Reveals That Adult Microglia Derive from Primitive Macrophagesrly life exercise may promote lasting brain and metabolic health through gut bacterial metabolites
Florent Ginhoux1,2,*, Melanie Greter1, Marylene Leboeuf1, Sayan Nandi3, Peter See2, Solen Gokhan4, Mark F. Mehler4,5, Simon J. Conway6, Lai Guan Ng2, E. Richard Stanley3, Igor M. Samokhvalov7, Miriam Merad1,*
Microglia are the resident macrophages of the central nervous system and are associated with the pathogenesis of many neurodegenerative and brain inflammatory diseases; however, the origin of adult microglia remains controversial. We show that postnatal hematopoietic progenitors do not significantly contribute to microglia homeostasis in the adult brain. In contrast to many macrophage populations, we show that microglia develop in mice that lack colony stimulating factor-1 (CSF-1) but are absent in CSF-1 receptor–deficient mice. In vivo lineage tracing studies established that adult microglia derive from primitive myeloid progenitors that arise before embryonic day 8. These results identify microglia as an ontogenically distinct population in the mononuclear phagocyte system and have implications for the use of embryonically derived microglial progenitors for the treatment of various brain disorders.
C-Myb+ Erythro-Myeloid Progenitor-Derived Fetal Monocytes Give Rise to Adult Tissue-Resident Macrophages
Guillaume Hoeffel, Jinmiao Chen, Yonit Lavin, Donovan Low, Francisca F. Almeida, Peter See, Anna E. Beaudin, Josephine Lum, Ivy Low, E. Camilla Forsberg, Michael Poidinger, Francesca Zolezzi, Anis Larbi, Lai Guan Ng, Jerry K.Y. Chan, Melanie Greter, Burkhard Becher, Igor M. Samokhvalov, Miriam Merad, Florent Ginhoux
Although classified as hematopoietic cells, tissue-resident macrophages (MFs) arise from embryonic precursors that seed the tissues prior to birth to generate a self-renewing population, which is maintained independently of adult hematopoiesis. Here we reveal the identity of these embryonic precursors using an in utero MF-depletion strategy and fate-mapping of yolk sac (YS) and fetal liver (FL) hematopoiesis. We show that YS MFs are the main precursors of microglia, while most other MFs derive from fetal monocytes (MOs). Both YS MFs and fetal MOs arise from erythro-myeloid progenitors (EMPs) generated in the YS. In the YS, EMPs gave rise to MFs without monocytic intermediates, while EMP seeding the FL upon the establishment of blood circulation acquired c-Myb expression and gave rise to fetal MOs that then seeded embryonic tissues and differentiated into MFs. Thus, adult tissue-resident MFs established from hematopoietic stem cell-independent embryonic precursors arise from two distinct developmental programs.