近日，瑞士联邦理工学院Timm Schroeder团队开发出一种可用于定量分泌分子的三维全组织数字成像方法，并揭示骨髓中缺少CXCL12梯度。该项研究成果发表在2019年12月5日出版的《细胞—干细胞》上。

研究人员报道了邻近连接法（PLA）对大量、原位成像的单个蛋白的应用，这个方法带有多个荧光通道且整合了3D定量的策略与软件。使用这个平台，研究人员量化了单个CXCL12趋化因子在粒细胞集落刺激因子（G-CSF）处理前后的骨髓（BM）分布。

研究人员发现普遍存在的CXCL12分布具有局部富集，但没有长距离梯度，这与当前关于CXCL12如何调控BM中造血干细胞和祖细胞（HSPC）迁移的假设相反。这种离散数字定量、大容量、多色成像，并具有单分子灵敏度的方法，可广泛应用于任何抗体表位和组织，从而能够进一步洞察组织的分子结构和细胞相互作用。

据悉，技术局限性阻碍了人们对包括潜在干细胞调节因子在内的各个分子如何分布在整个组织和干细胞微环境中的理解。

附：英文原文

Title: A 3D Tissue-wide Digital Imaging Pipeline for Quantitation of Secreted Molecules Shows Absence of CXCL12 Gradients in Bone Marrow

Author: Leo Kunz, Timm Schroeder

Issue&Volume: 2019/12/05

Abstract: Technological limitations have hampered understanding of how individual molecules,including putative stem cell regulators, are distributed throughout tissues and stemcell niches. Here, we report adaptation of the proximity ligation assay (PLA) forlarge-volume, in situ imaging of individual proteins with multiple additional fluorescent channels withintegrated 3D quantification strategies and software. Using this platform, we quantifiedthe bone marrow (BM) distribution of individual CXCL12 chemokine proteins, both beforeand after their depletion by granulocyte-colony stimulating factor (G-CSF) treatment.We found ubiquitous CXCL12 distributions with local enrichments but no long-rangegradients, in contrast to current assumptions about how CXCL12 controls migrationof hematopoietic stem and progenitor cells (HSPCs) within BM. This pipeline for discretedigital quantitative, large-volume, multicolor imaging, with up to single-moleculesensitivity, may be broadly applied to any antibody epitope and tissue, enabling furtherinsights into molecular organization of tissues and cellular interactions.

DOI: 10.1016/j.stem.2019.10.003

Source: https://www.cell.com/cell-stem-cell/fulltext/S1934-5909(19)30424-2