Novo Nordisk Foundation Center for Stem Cell Biology, University of Copenhagen, Blegdamsvej 3b, 2200, Copenhagen N, Denmark.
Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, 2100, Copenhagen, Denmark.
Commun Biol. 2022 Apr 29;5(1):402. doi: 10.1038/s42003-022-03349-1.
Material properties of living matter play an important role for biological function and development. Yet, quantification of material properties of internal organs in vivo, without causing physiological damage, remains challenging. Here, we present a non-invasive approach based on modified optical tweezers for quantifying sub-cellular material properties deep inside living zebrafish embryos. Material properties of cells within the foregut region are quantified as deep as 150 µm into the biological tissue through measurements of the positions of an inert tracer. This yields an exponent, α, which characterizes the scaling behavior of the positional power spectra and the complex shear moduli. The measurements demonstrate differential mechanical properties: at the time when the developing organs undergo substantial displacements during morphogenesis, gut progenitors are more elastic (α = 0.57 ± 0.07) than the neighboring yolk (α = 0.73 ± 0.08), liver (α = 0.66 ± 0.06) and two mesodermal (α = 0.68 ± 0.06, α = 0.64 ± 0.06) progenitor cell populations. The higher elasticity of gut progenitors correlates with an increased cellular concentration of microtubules. The results infer a role of material properties during morphogenesis and the approach paves the way for quantitative material investigations in vivo of embryos, explants, or organoids.
生物材料特性对于生物功能和发育起着重要作用。然而，在不造成生理损伤的情况下，定量测量体内内部器官的材料特性仍然具有挑战性。在这里，我们提出了一种基于改良光学镊子的非侵入性方法，用于定量测量活体斑马鱼胚胎内部的亚细胞材料特性。通过测量惰性示踪剂的位置，可以定量测量前肠区域细胞的材料特性，深度可达 150μm 进入生物组织。这产生了一个指数α，它描述了位置功率谱和复剪切模量的标度行为。测量结果表明了不同的力学特性：在发育器官在形态发生过程中发生显著位移时，肠道祖细胞比相邻的卵黄（α=0.73±0.08）、肝脏（α=0.66±0.06）和两个中胚层（α=0.68±0.06，α=0.64±0.06）祖细胞群体更有弹性（α=0.57±0.07）。肠道祖细胞的更高弹性与微管的细胞浓度增加有关。这些结果推断了材料特性在形态发生过程中的作用，并且该方法为活体胚胎、外植体或类器官的定量材料研究铺平了道路。
