# Xenoline-polarized macrophages as a physiologically relevant in vitro model of tumor-associated macrophages in glioblastoma

## TL;DR

Researchers developed a new lab model using patient-derived cells to better mimic tumor-associated macrophages in glioblastoma, offering a more accurate way to study cancer-immune interactions.

## Contribution

A novel in vitro model using xenoline-polarized macrophages that better reflects the heterogeneity of tumor-associated macrophages in glioblastoma.

## Key findings

- Xenoline-polarized macrophages adopt transcriptional signatures similar to TAM subsets in patient samples.
- Macrophages polarized with a radiation-selected xenoline show gene patterns linked to interferon response and hypoxia.
- Phenotypic validation revealed discrepancies between predicted and observed macrophage functions.

## Abstract

Tumor-associated macrophages (TAMs) are the most abundant non-cancerous cell type in glioblastoma (GBM) and heavily influence GBM biology, contributing to tumor progression, therapeutic resistance, immune evasion, and neovascularization. Current in vitro models that utilize IL-4/IL-13 stimulation fail to capture the transcriptional and functional heterogeneity of TAMs observed in vivo. In this study, we utilize a serum-free indirect co-culture model with patient-derived xenolines to polarize primary human macrophages and characterize their molecular and functional phenotypes. We demonstrate that xenoline-polarized macrophages diverge from classical M1/M2 states and instead adopt transcriptional signatures reflective of TAM subsets identified from patients. Notably, macrophages polarized with the radiation-therapy selected xenoline, JX14P-RT, exhibited gene expression patterns enriched for interferon response and hypoxia, mirroring recurrent GBM samples. In contrast, JX14P TAMs showed enrichment in phagocytic gene sets. Functional validation of these phenotypes revealed discrepancies between the transcriptionally predicted and observed phenotypes, emphasizing the importance of integrating phenotypic validation in sequencing studies. Altogether, our findings establish xenoline-polarized macrophages as a more physiologically relevant alternative to traditional models, offering a useful model for studying tumor-immune interaction in vitro.