ESTRO 2024 - Abstract Book

S5224

Radiobiology - Microenvironment

ESTRO 2024

Exposure to ionizing irradiation can induce inflammation, which is involved in the response to treatments in both tumors and normal tissues [1]. Besides the release of several cytokines, the inflammatory response can induce alterations in the microvascular wall permeability.

We propose an advanced in-vitro model based on microvasculature-on-chip technology. With this device, we evaluate the inflammatory response and the microvascular wall alteration following ionizing irradiation exposure.

Material/Methods:

We first constructed the microvasculature-on-chip by designing the microfluidic chip to accommodate three dimensional cell cultures supporting vasculogenic-like microvascular network formation. The microfluidic chip was then fabricated using the classical soft-lithography technique [2] (Figure 1).

To create the microvascular network, we introduced a fibrin-thrombin gel containing Human Umbilical Vein Endothelial Cells (HUVECs, 4.5 M/ml) and Human Dermal Fibroblasts (4.5 M/ml) into the central channel of the chip. After seven days, pseudo-vasculogenesis was completed, and the microvascular network was fully developed (Figure 1).

We performed irradiations at 2, 5, 8, and 10 Gy with 6 MV photons (dose rate 2.8 Gy/min). The dose was calculated using the treatment planning system, employing an ad-hoc phantom to simulate surrounding tissues.

At two time points after irradiation, we collected the media to measure cytokine concentrations using the (QAH INF-1-1) Human Inflammation Array Q1 (RayBiotech). Here, we present results for IL6, IL8, and MCP1(CCL2). These data are coupled with previous analysis of vascular wall permeability to TRITC-labelled 40kDa dextran through confocal imaging [3].

Results:

The microvasculature-on-chip enabled the consistent production of microvascular networks [3].

Three hours after irradiation, we do not report modulation of IL6, even if there is a small difference at 5 Gy (p < 0.001). Conversely, after 24 hours, IL6 increased linearly with dose dependence with a slope of 253 (pg/ml)/Gy (95% CI: 215-291 (pg/ml)/Gy, R² = .94, Figure 2).

IL8 differed from the sham-irradiated control at 10 Gy, three hours after irradiation (p = 0.04, Figure 2).

MCP1(CCL2) increased with the dose up to 5 Gy after 3 hours but then decreased at 10 Gy (Figure 2).