The density of infiltrating T cells and macrophages in the parental tumour correlates with growth rate of tumoroids established from colorectal adenocarcinoma

Abstract

The aim of the present study was to investigate the correlation between the density of infiltrating T cells and macrophages in the parental colorectal cancer (CRC) and the growth rate of tumoroids (i.e. a patient-derived in vitro 3D model). Tumoroids were established from fresh specimens of primary and metastatic CRC from 29 patients. The in vitro growth rate of tumoroids was monitored by automated imaging. The density of infiltrating T cells and macrophages was determined in the centre of the tumour (CT) and at the invasive margin (IM) of the parental tumours. This was performed by digital image analysis on the whole-slide scanned images using Visiopharm^® software. Tumoroids with higher density of infiltrating CD3+ lymphocytes in the IM of their parental tumour showed a higher growth rate (P < .0005). The average relative growth rate (log10) during the period from day 1 to day 11 was 0.364 ± 0.006 (mean ± SD) for the CD3+ (IM)-high group and 0.273 ± 0.008 (mean ± SD) for the CD3+ (IM)-low group. In contrast, the density of CD68+ infiltrating macrophages in the parental tumours showed significant inverse effect on the growth rate of the tumoroids (P < .0005). The present study showed that the density of immune cells in the parental CRC correlates with the growth rate of the tumoroids. The future perspective for such a 3D model could be in vitro investigations of the tumour-associated inflammatory microenvironment as well as personalized cancer immunotherapy.

Keywords: colorectal adenocarcinoma; digital pathology; in vitro 3D culture; tumour-associated T lymphocytes; tumour-associated macrophages.

Figure 1

Automated quantification of the immune cells in colon adenocarcinoma by digital image analysis. Main figure: The centre of the tumour (blue marking) and the invasive margin (red marking). A‐C, Recognition of CD3+, CD8+ and CD68+ cells respectively. The left panels show the IHC‐stained section before analysis, and the right panels show the areas detected positive, indicated by green label, adjacent to the background area, indicated by the blue label. (bar = 500 µm)

Figure 2

Scatter plot with fitted regression line showing relative growth rates of tumoroids established from the tumours with the highest 50% (blue colour) vs the lowest 50% (green colour) density of CD3+ cells at the invasive margin (IM) of their parental tumours. Each circle represents the relative rate of growth area in a specific culture well for a specific patient. The correlation between increasing number of the CD3+ cells at IM of the parental tumour and the higher growth rate of tumoroids was significant during the period from day 1 to day 11 (P < .0005)

Figure 3

Scatter plot with fitted regression line showing relative growth rates of tumoroids established from the tumours with the highest 50% (blue colour) vs the lowest 50% (green colour) density of CD68+ cells at the invasive margin (IM) of their parental tumours. Each circle represents the relative rate of growth area in a specific culture well for a specific patient. The statistical analysis showed a significant correlation between increasing number of the CD68+ cells at IM of the parental tumour and the lower growth rate of tumoroids during the period from day 1 to day 11 (P < .0005)