The Ultrastructural Analysis of Human Colorectal Cancer Stem Cell-Derived Spheroids and Their Mouse Xenograft Shows That the Same Cells Types Have Different Ratios.

Michela Relucenti,Rui Chen,Maria Laura De Angelis,Federica Francescangeli,Vito D’Andrea,Ann Zeuner,Selenia Miglietta,Xiaobo Li,Alessandra Boe,Emanuela Pilozzi,Giuseppe Familiari

doi:10.3390/biology10090929

Michela Relucenti, Rui Chen + Show 9 more

Open Access

https://doi.org/10.3390/biology10090929

Copy DOI

Abstract

Simple SummaryA comparative ultrastructural and flow cytometric analysis of colorectal cancer-derived spheroids and their mouse xenografts showed that they both contain the same cell types but with different ratios, reflecting the interaction of cancer cells, respectively, with the in vitro and in vivo microenvironment.Spheroids from primary colorectal cancer cells and their mice xenografts have emerged as useful preclinical models for cancer research as they replicate tumor features more faithfully as compared to cell lines. While 3D models provide a reliable system for drug discovery and testing, their structural complexity represents a challenge and their structure-function relationships are only partly understood. Here, we present a comparative ultrastructural and flow citometric analysis of patient colorectal cancer-derived spheroids and their mice xenografts. Ultrastructural observations highlighted that multicellular spheroids and their xenografts contain the same cancer cell types but with different ratios, specifically multicellular spheroids were enriched in cells with a stem-like phenotype, while xenografts had an increased amount of lipid droplets-containing cells. The flow cytometric analysis for stem cell marker and activity showed enrichment of stem-like cells presence and activity in spheroids while xenografts had the inverse response. Our results evidence the effects on cancer cells of different in vitro and in vivo microenvironments. Those differences have to be paid into account in designing innovative experimental models for personalized drug testing.

Highlights

This article is an open access articleInternational Agency for Research on Cancer estimated in 2020 colorectal cancer as the third worldwide most common malignancy and second cancer-causing patient death [1].Colorectal cancer has several sub-types and every single cancer, from a single patient, contains a heterogeneous cell population, which responded in a very different way to the conventional therapies
Our work aims to fill this gap investigating systematically by flow cytometry, scanning electron microscopy (SEM) and transmission electron microscopy (TEM), the ultrastructural features of spheroids derived from patient colorectal cancer with that of the tumor-derived from spheroids xenograft in mice
We provide a comparative analysis, by TEM, SEM and flow cytometry, of patient colorectal cancer-derived spheroids with that of cancer induced by their mouse xenograft

Summary

Introduction

This article is an open access articleInternational Agency for Research on Cancer estimated in 2020 colorectal cancer as the third worldwide most common malignancy and second cancer-causing patient death [1].Colorectal cancer has several sub-types and every single cancer, from a single patient, contains a heterogeneous cell population, which responded in a very different way to the conventional therapies (chemotherapy and or radiotherapy). Spheroids are useful in preclinical studies on drug sensitivity and effectiveness [10] Another experimental model that allows overcoming in vitro culture disadvantages is the patient-derived xenograft model. Even if the mouse provides a microenvironment that lacks in vitro cultures, this technique has some disadvantages: low rate of engraftment, it is money and time expensive, genetic and epigenetic changes due to the host are different, and being the mouse immunocompromised, interactions with the immune system are incomplete [11,12,13,14,15,16] Both spheroids and xenotransplants are well studied by genetic and proteomic approaches [10,17], but scarce studies instead analyze their ultrastructure utilizing scanning electron microscopy (SEM) and transmission electron microscopy (TEM); in addition, the microstructure of spheroids is described in these studies only briefly [17,18,19,20]. In the literature, no studies reported an ultrastructural investigation of patient colorectal cancer-derived spheroids compared with that of the tumor resulted from spheroids xenograft in mice

Objectives

Methods

Discussion

Conclusion