Supplementary Material for: A Novel In Vivo Rat Mesentery Model for Studying Tumor Spheroid-Induced Microvascular Remodeling

Introduction: The tumor microenvironment is comprised of neoplastic cells and a variety of host cell types. Investigation of cell dynamics within this environment has motivated in vitro and ex vivo biomimetic model development. Our lab recently introduced the tumor spheroid-rat mesentery model to investigate cancer-induced lymphatic/blood vessel remodeling. To validate the physiological relevance of this model, the objective of this study was to determine the effect of tumor spheroids on microvascular remodeling after transplantation onto rat mesenteric.
Methods: Spheroids derived from H1299 lung cancer cells were seeded onto rat mesenteric tissues during a survival surgical procedure. Tissues were harvested 3-5 days post-seeding and stained with PECAM and LYVE-1 to identify blood and lymphatic vessels respectively.
Results: At all timepoints, cancer cells remained adhered to the tissue. Tissues seeded with tumor spheroids were shown to have increased vascular density, capillary sprouting, and tortuosity compared to sham tissues exposed to sterile saline only. Tumor spheroids also induced the formation of lymphatic/blood vessel connections and LYVE-1 negative protrusions emerging from lymphatic vessels.
Conclusion: Overall, this study underscores the use of in vivo modeling to aid in the discovery of novel vascular growth dynamics and offers new methodologies for studying tumor-induced remodeling.

引言：肿瘤微环境（tumor microenvironment）由肿瘤细胞（neoplastic cells）及多种宿主细胞类型构成。对该环境内细胞动态的研究推动了体外（in vitro）及离体（ex vivo）仿生模型（biomimetic model）的开发。本实验室近期建立了肿瘤球-大鼠肠系膜模型（tumor spheroid-rat mesentery model），以探究癌症诱导的淋巴/血管重塑（cancer-induced lymphatic/blood vessel remodeling）。为验证该模型的生理相关性（physiological relevance），本研究旨在明确肿瘤球移植至大鼠肠系膜后对微血管重塑（microvascular remodeling）的影响。

方法：在存活性手术（survival surgical procedure）过程中，将源自H1299肺癌细胞的肿瘤球接种于大鼠肠系膜组织。接种后3-5天取材，并用PECAM和LYVE-1分别染色以识别血管和淋巴管。

结果：在所有时间点，癌细胞均保持对组织的粘附。与仅暴露于无菌生理盐水的假手术组织（sham tissues）相比，接种肿瘤球的组织显示出血管密度（vascular density）增加、毛细血管出芽（capillary sprouting）增多及迂曲度（tortuosity）升高。肿瘤球还诱导了淋巴/血管连接的形成，以及源自淋巴管的LYVE-1阴性突起（LYVE-1 negative protrusions）。

结论：总体而言，本研究强调了体内模型（in vivo modeling）在助力发现新型血管生长动态（novel vascular growth dynamics）中的应用，并为研究肿瘤诱导的重塑（tumor-induced remodeling）提供了新的方法学（methodologies）。