Tissue clearing / 3D imaging

一行要約

Tissue clearing (CLARITY / iDISCO+ / CUBIC / uDISCO) で組織を透明化 → 蛍光標識 → light-sheet microscopy で撮像することで、whole-organ レベルの 3D 細胞分布 / 脈管 / 免疫細胞 / 腫瘍細胞分布を non-destructive に取得する手法。脳転移領域では single brain met < 100 µm レベルで全脳分布を mappingでき、leptomeningeal extension, perivascular spread, immune infiltration 3D 構造を解像。EV biodistribution の in vivo 追跡や PDX 全身 metastatic burden の定量にも応用。

原理

(1) 固定 + 標識: 4% PFA 固定 → 抗体 / fluorophore 染色 (whole-mount または vibratome 厚切片)。(2) Clearing: organic solvent (iDISCO+, 3DISCO, uDISCO = THF / DBE / BABB) で脂質除去・屈折率均一化、または hydrogel embedding (CLARITY) や urea-based (CUBIC, ScaleS) で透明化。(3) Imaging: light-sheet (LSFM) で薄い光シートで sectioning 撮像、photobleaching / acquisition 時間を大幅短縮。(4) 解析: Imaris / Arivis / napari で 3D segmentation, Fiji BigStitcher で stitching, ClearMap / TRAILMAP で whole-brain quantification。

Expansion microscopy (ExM) は逆アプローチで試料を等方的に膨張 → super-resolution 取得 (4-20 倍)。

主要エビデンス / 適用領域

• Whole-brain metastasis mapping: KP-NSCLC / B16 melanoma 模型で全脳の脳転移分布を mapping、preferential niche (perivascular, gray-white junction) 同定
• Leptomeningeal disease 3D: CSF 経路に沿った tumor cell 分布を 3D 描出
• Vascular co-option: brain met が既存血管に沿って成長する vascular co-option を 3D で可視化
• Immune infiltration 3D: TIL の腫瘍周囲 vs 内部分布を whole-tumor で定量
• EV biodistribution: 蛍光標識 EV の全身 organ-specific homing 動態
• PDX systemic burden: NSG マウス全身の micro-metastatic foci 定量

適用分野と限界

• 強み: whole-organ / non-destructive 3D, micro-metastasis (<100 µm) 検出, perivascular / leptomeningeal architecture 保存, antibody / GFP / dye 多様な標識
• 限界: clearing protocol で antibody epitope 損失あり (iDISCO+ は耐性), large data (~TB / sample) handling, 定量 standardization 不足, FFPE 適用困難 (fresh / fixed のみ), 専門設備 (light-sheet) 依存

Open Questions

• Multi-color clearing: 5+ 色同時染色の standardization
• Clearing × spatial transcriptomics の hybrid (3D spatial omics)
• Clinical resection sample: human surgical specimen への展開
• AI-driven 3D segmentation: foundation model for volumetric biology

関連エンティティ

• 補完手法: Multiplex-IF-imaging / Spatial-transcriptomics / Digital-pathology / CODEX-PhenoCycler
• 関連細胞: Reactive-astrocyte / Microglia / Border-associated-macrophage / Endothelial-cell
• 関連概念: Brain-metastasis-immune-microenvironment / BBB-disruption-in-brain-metastasis / Leptomeningeal-metastasis / Pre-metastatic-niche / EV-organotropism

関連論文

Basic-Brain metastasis

• Chen et al. FrontOncol 2026 — Stereotactic radiotherapy for brain metastases indications, dose fractionation, technological innovations, and evolving
• Hill et al. NatCommun 2025 — Molecular profiling of brain endothelial cell to astrocyte endfoot communication in mouse and human
• Wei et al. Nature 2026 — Tumour-brain crosstalk restrains cancer immunity via a sensory-sympathetic axis
• Brown et al. Science 2018 — Lymph node blood vessels provide exit routes for metastatic tumor cell dissemination in mice

Basic-Extracellular vesicles

• Shurer et al. Cell 2019 — Physical principles of membrane shape regulation by the glycocalyx
• Swanton et al. Cell 2024 — Embracing cancer complexity Hallmarks of systemic disease
• Chayama et al. Cell 2026 — Physiological brain clearance architecture revealed by neuronal protein tracing
• Arya et al. NatCellBiol 2022 — Ceramide-rich microdomains facilitate nuclear envelope budding for non-conventional exosome formation
• Son et al. NatCommun 2025 — Fusogenic lipid nanoparticles for rapid delivery of large therapeutic molecules to exosomes
• Verweij et al. NatMethods 2021 — The power of imaging to understand extracellular vesicle biology in vivo

Basic-Immunotherapy

• Goyette et al. JCellSci 2019 — How does T cell receptor clustering impact on signal transduction
• Esterhazy et al. Nature 2019 — Compartmentalized gut lymph node drainage dictates adaptive immune responses

Basic-Neutrophil and myeloid cell

• Adrover et al. Nature 2025 — Neutrophils drive vascular occlusion, tumour necrosis and metastasis
• Fan et al. Nature 2026 — Submicrometre sampling of living cells by macrophages
• Chakarov et al. Science 2019 — Two distinct interstitial macrophage populations coexist across tissues in specific subtissular niches

Basic-Others

• Gao et al. Cell 2026 — Nanoparticles hijack calvarial immune cells for CNS drug delivery and stroke therapy
• deLaunoit et al. Cell 2026 — The spatiotemporal dynamics of postnatal vascularization in the mouse brain
• Leunig et al. NatRevImmunol 2025 — Connection and communication between the nervous and immune systems
• McMahon et al. NatStructMolBiol 2018 — Yeast surface display platform for rapid discovery of conformationally selective nanobodies

Basic-Tumor microenvironment

• Nigri et al. CancerDiscov 2026 — Myofibroblasts induce neuroplasticity to promote pancreatic inflammation and cancer progression

Clinical-NSCLC-Driver negative

• Salazar et al. JAMAOncol 2017 — Association of delayed adjuvant chemotherapy with survival after lung cancer surgery
• Rauer et al. NEnglJMed 2019 — Treatment of progressive multifocal leukoencephalopathy with pembrolizumab

Clinical-Others

• Vishwanath et al. NatMed 2026 — General-purpose large language models outperform specialized clinical AI tools on medical benchmarks

Clinical-SCLC

• Rittberg et al. ClinLungCancer 2020 — Effect of hospitalization during first chemotherapy and performance status on small-cell lung cancer outcomes