Transcriptional landscape of the interaction of human Mesenchymal Stem Cells with Glioblastoma in bioprinted co-cultures

Abstract

Background The interaction between mesenchymal stem cells (MSC) and Glioblastoma (GBM), although potentially of the highest importance, is ill-understood. This is due, in part, to the lack of relevant experimental models. The similarity between the in vitro situations and the in vivo situation can be improved by 3D co-culture as it reproduces key cell–cell interactions between the tumor microenvironment (TME) and cancer cells. Methods MSC Can acquired characteristics of cancer associated fibroblasts (CAF) by being cultured with conditioned medium from GBM cultures and thus are called MSCCAF. We co Cultured MSCCAF with patient derived GBM in a scaffold 3D bioprinted model. We studied the response to current GBM therapy (e.g. Temozolomide +/Radiation) on the co cultures by bulk transcriptomic (RNA Seq) and epigenetic (ATAC Seq) analyses Results The transcriptomic modifications induced by standard GBM treatment in bioprinted scaffolds of mono- or co-cultures of GBM ± MSC can be analyzed. We found that mitochondrial encoded OXPHOS genes are overexpressed under these conditions and are modified by both co-culture and treatment (chemotherapy ± radiation). We have identified two new markers of MSC/GBM interactions, one epigenetically regulated (i.e. TREM-1) associated with an increased overall survival in GBM patients and another implicated in post-transcriptional regulation (i.e. the long non-coding RNA, miR3681HG), which is associated with a reduced overall survival in GBM patients.

1. Introduction

Glioblastoma (GBM) is the predominant primary cancer in human adults with a median survival following diagnosis of 12 to 15 months, with less than 10% of people surviving longer than five years [1]. The most current common treatment for GBM is a combination of complete (when possible) surgical resection, followed by radiotherapy and concomitant chemotherapy with the alkylating agent Temozolomide (TMZ) [2]. GBM are extremely heterogeneous and exhibit a very complex tumor microenvironment (TME), which render these tumors difficult to treat [3]. Today the main axis of research emphasizes on new therapies that are more “patient-specific” and which take into account a prediction on the mechanisms of resistance [4]. One way to achieve this goal is to use accurate in vitro tests that allow drug or innovative treatment screening on a personalized basis [5].

Among the cells present in the GBM microenvironment are the mesenchymal stem cells (MSC), the origins of which are ill-defined [6, 7]. Of note, the presence of MSC has been correlated with the survival of the patients [8]. However, so far, no clear mechanisms have been established to explain both the tropism and the mechanism(s) of action of MSC in GBM [9]. We have recently shown, in three-dimensional (3D) co-cultures, that the influences of MSC on GBM are multiple and involve both molecule and organelle transfers through connecting structures such as tunneling nanotubes (TNT) [10] and extracellular vesicles (EV) [11]. Strikingly, the co-culture of MSC and GBM affect both cellular types as, for example, it allows MSC to acquire a cancer-associated fibroblast (CAF) phenotype and properties that are specific for each GBM [12].

The current paradigm of in vitro studies is currently shifting from the classical two-dimensional (2D) to 3D-cultures. 3D-cultures can be developed with or without a scaffold. Scaffold-based 3D-cultures can use solid scaffold or hydrogels derived from extracellular matrix, proteins, polymer and many other materials. It is expected that 3D-cultures could influence the