Powerful Spheroid Imaging Methodology using DRAQ5

This new work builds on earlier studies to determine a best methodology to clear and image tumour spheroids (Nürnberg et al. 2020) previously reviewed here.  This showed the performance advantage of a low-cost glycerol-based RI correction and nucleus counterstaining with DRAQ5.  The authors, from the laboratory of Rüdiger Rudolph (Mannheim Univ. of Applied Sciences, DE), described a full workflow from tumor spheroid seeding through treatment, and onto whole mount clearing, staining, immunofluorescence imaging and image analysis.

A significant part of this work was the deployment of a deep-learning-based segmentation tool which could give single cell information within the context of the complete 3D spheroid whole mount rather than the limited information available from a cryosection or a 2D optical section of a spheroid.  One fascinating finding was that it was possible to differentiate the tumor and stromal (fibroblast) cells on the basis of nuclear morphology alone which further simplifies the preparative steps and aids the interrogation of the interactions between two cell types in co-culture.

Pancreatic cell line mono-cultures and co-cultures with fibroblasts were exposed to different cytostatic treatments and show features consistent with previous findings on these drugs and the presence or absence of the co-cultured stromal cells.

The results show strong correlation between the whole mount procedure and cryosections.  Using their procedure, DRAQ5 maintained good penetration and staining of nuclei throughout the spheroids. Where can I buy DRAQ5?

The authors concede a limitation of the study in that these results are on single pancreatic cancer cell line but they signal their intention to test their workflow on patient material with the ultimate goal of informing personalized medicine.

References:

Vitacolonna, Mario, et al. "A spheroid whole mount drug testing pipeline with machine-learning based image analysis identifies cell-type specific differences in drug efficacy on a single-cell level." BMC cancer 24.1 (2024): 1542

Clear sense - optical clearing of microtissues, tissue slices. BioStatus Blog, June 2021.