講演者：　長澤　丘司　（大阪大学大学院生命機能研究科/医学系研究科 幹細胞・免疫発生研究室  教授）

演題：　The microenvironmental niches for hematopoietic stem and progenitor cells in the bone marrow

日時： 7月27日（水） 12:00-13:00
会場： 発生医学研究所1階　カンファレンス室

Abstract:

All blood cells, including immune cells, are generated from hematopoietic stem cells (HSCs) in the bone marrow. HSCs are in contact with and maintained by restricted microenvironments, termed niches; however, the identity of cells creating HSC niches has been a subject of longstanding debate. We focused our analysis on the chemokine CXCL12, which is essential for homing and maintenance of HSCs and development of immune cells in the bone marrow, and identified a population of mesenchymal cells with long processes, expressing high amounts of CXCL12, termed CXCL12-abundant reticular (CAR) cells. We revealed that most HSCs adjoined the processes of CAR cells and that ablation of CAR cells in vivo severely impaired the adipogenic and osteogenic differentiation potential of bone marrow cells and production of stem cell factor (SCF) as well as CXCL12, and led to a marked reduction in the numbers of hematopoietic stem and progenitor cells (HSPCs), indicating that CAR cells are adipo-osteogenic progenitors, which create a HSPC niche. Recently, we found that the transcription factor Foxc1 was preferentially expressed in CAR cells in the bone marrow and was essential for development and maintenance of the HSPC niche, enhancing CXCL12 and SCF expression, and inhibiting adipogenic processes in CAR cells. The features of cells, which play a dominant role in creating HSC niches in the bone marrow will be discussed.

References：

(1) Sugiyama, T. et al., Immunity 25, 977 (2006).

(2) Omatsu, Y. et al.,  Immunity 33, 387 (2010).

(3) Omatsu, Y. et al.,  Nature 508, 536 (2014).

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担当分野：　国際先端医学研究機構　滝澤 仁