Summary

小鼠胚胎中早期心脏祖细胞的实时成像

Published: July 12, 2022
doi:

Summary

我们提出了小鼠胚胎培养和成像的详细方案,可实现心脏祖细胞的3D +时间成像。该视频工具包解决了成功进行实时成像所需的关键技能,否则很难从纯文本出版物中获得。

Abstract

心脏发育的第一步意味着细胞行为和分化的剧烈变化。虽然对固定胚胎的分析允许在静止快照中详细研究特定的发育阶段,但实时成像通过在胚胎发育过程中成像来捕获动态形态发生事件,例如细胞迁移、形状变化和分化。这补充了固定分析,并扩展了对胚胎发生过程中器官如何发育的理解。尽管具有优势,但由于其技术挑战,实时成像很少用于小鼠模型。早期小鼠胚胎在 离体 培养时很敏感,需要有效处理。为了促进实时成像在小鼠发育研究中的更广泛应用,本文提出了一种双光子实时显微镜的详细方案,该协议允许在小鼠胚胎中长期采集。除方案外,还提供了有关胚胎处理和培养优化的提示。这将有助于了解早期小鼠器官发生的关键事件,增强对心血管祖细胞生物学的理解。

Introduction

心脏在胚胎发生早期形成,开始向整个胚胎输送营养物质,同时继续发育1。在小鼠胚胎中,原肠胚形成开始一天半后,一个基本的心脏器官在前极23处组装。到早期条纹(ES)阶段,外胚层中的心脏祖细胞通过原始条纹进入新生的中胚层456并开始迁移到前极在那里它们分化形成原始心脏管。在整个过程中,除了迁移7之外,早期心脏祖细胞还经历细胞重排,形状转换和分化(图1)。

近一个世纪以来,早期的心脏祖细胞因其同时分化和构建功能器官的非凡能力而吸引了研究人员。在过去的二十年中,克隆分析和条件敲除模型表明,早期心脏发育涉及高度动态过程中的不同细胞来源8910。然而,原始心脏管的3D结构及其形态发生的动态性质使其研究具有挑战性(图1),我们远未了解其全部复杂性11

为了研究这些动态细胞过程,实时成像方法现在提供了前所未有的细节7121314在小鼠模型中,实时方法是询问静态分析难以解决的发展主题的关键7,1315虽然长期离体培养和强大的显微镜装置正在快速发展16,17很少有研究人员具备成功对活胚胎进行成像的专业知识。尽管纸质出版物提供了足够的技术细节来重现实时成像实验,但如果没有视觉示例或点对点帮助,一些技能和技巧很难掌握。为了加速这一学习过程并在实验室中推广实时成像的使用,我们组装了一个视频协议(图2),该协议收集了对原肠胚小鼠胚胎进行实时成像的必要技能。

Figure 1
图1:小鼠胚胎中心脏祖细胞的早期分化,从原肠胚形成开始到原始心脏管形成之前的阶段。 心脏祖细胞在原肠胚形成开始后不久进入中胚层,迁移到胚胎的另一侧。形态和胚胎日(E)阶段写在图表的顶部。虚线箭头描绘了原肠胚形成过程中原始心脏管祖细胞的迁移轨迹。这个数字改编自11。缩写:ES = 早期连胜;MS = 中间条纹;EHF = 早期头部折叠。 请点击此处查看此图的大图。

Figure 2
2:早期心脏祖细胞实时成像的工作流程图。 请点击此处查看此图的大图。

Protocol

所有动物程序均由CNIC动物实验伦理委员会,马德里共同体批准(参考PROEX 220/15),并符合欧盟指令2010/63EU和关于保护用于实验和其他科学目的的动物的建议2007/526 / EC,根据Real Decreto 1201/2005在西班牙法律中强制执行。 该方案包括使用来自荧光转基因小鼠系的两名雄性报告NOTCH活性Tg(CBF:H2BVenus,+)18。有关本协议中使用的材料、动物和设备的详细信息,请?…

Representative Results

我们使用该协议来可视化早期心脏祖细胞的NOTCH信号激活,这些信号在原始心脏管形态发生期间即将分化为内皮细胞。为此,我们将野生型C57BL / 6-N小鼠与Tg(CBF:H2BVenus,+)小鼠18 杂交,以获得通过黄色荧光蛋白Venus报告NOTCH活性的胚胎。在E7.5时,金星荧光存在于整个神经外胚层,在内脏和胚胎外中胚层有一些阳性细胞核。4小时后,内皮祖细胞激活金星并组装形成心内膜管和下?…

Discussion

早期的心脏祖细胞组织在一个原始的心脏管中,该管在仍在形成时就开始跳动。了解这一过程是如何发生的,是将广泛的先天性心脏缺陷确定为特定形态发生事件的关键。为此,实时成像提供了一个机会来研究正常和有缺陷的胚胎发育,并提高时间分辨率。这对于研究早期心脏祖细胞特别有用,因为它们通过多种分化和迁移行为快速过渡7。

由于我们可以在?…

Divulgaciones

The authors have nothing to disclose.

Acknowledgements

作者感谢Kenzo Ivanovitch博士以前在这种方法上的工作,以及Shigenori Nonaka博士(日本国立自然科学研究所)的小组提供了胚胎安装的初步专业知识。这项研究得到了西班牙科学和创新部的Grant PGC2018-096486-B-I00和欧盟地平线2020计划的Grant H2020-MSCA-ITN-2016-722427和FEDER Andalucía 2014-2020运营计划的MT和赠款1380918的支持。MS得到了La Caixa基金会博士奖学金(LCF / BQ / DE18 / 11670014)和生物学家公司旅行奖学金(DEVTF181145)的支持。CNIC得到了西班牙科学部和ProCNIC基金会的支持。

Materials

#55 Forceps Dumont  11295-51
35 mm Dish with glass coverslip bottom 14 mm Diameter Mattek P35G-1.5-14-C
35 mm vise table  Grandado SKU 8798771617573
50 mL tubes BD Falcon 352070
Distilled water
DMEM – Dulbecco's Modified Eagle Medium Gibco 11966025  with L-Glutamine, without Glucose, without Na Pyruvate
Fetal Bovine Serum Invitrogen 10438-026
Fluorescent reporter transgenic mice (Tg(CBF:H2BVenus,+)  JAX
Fluorobrite DMEM ThermoFisher A1896701  DMEM for live-cell imaging
High-vacuum silicone grease Dow Corning Z273554-1EA
Holder for wires Perlen Pressen pwb1
LSM 780 Upright microscope Zeiss 
MaiTai Deepsee far red pulsed-laser tuned at 980 nm Spectra-Physics
Non Descanned Detectors equipped with the filter sets
cyan-yellow (BP450-500/BP520-560), green-red (BP500-520/BP570-610) and yellow-red (BP520-560/BP645-710)
Zeiss 
Obj: 20x water dipping 1.0 NA, long working distance Zeiss 
P1000 and P200 pipettes
Paraffin Oil Nidacon VNI0049
Penicillin-streptomycin Invitrogen 15070-063 (the final concentration should be 50 μg/mL penicillin and 50 μg/mL streptomycin)
Petri dishes 35 mm x 10 mm BD Falcon 351008
Pipette tips
Polymethyl methacrylate  Reused from old laboratory equipment
Rat Serum culture embryo, male rats SPRAGUE DAWLEY RjHan SD Janvier Labs 9979
Set of 160 mm fines RS PRO 541-6933
Standard 1.0 mm glass capillaries Anima Lab  1B100F-3
Sterile 0.22 μm syringe filter Corning 431218
Sterile 5 mL syringe Fisher Scientific 15809152
Tungsten needles
Ultrasonic homogeniser (sonicator) Bandelin BASO_17021

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Sendra, M., Mañes, J., Domínguez, J. N., Torres, M. Live Imaging of Early Cardiac Progenitors in the Mouse Embryo. J. Vis. Exp. (185), e64273, doi:10.3791/64273 (2022).

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