Comparison of different tissue dissociation methods for the analysis of the human brain tumour immune microenvironment (TIME)

The purpose of this experiment was to compare the recovery of immune cells from human brain metastases following tissue dissociation with different enzymatic and non-enzymatic methods.
Conclusion:
We found that mechanical dissociation of human brain metastasis tissue leads to an overall poor cellular yield, making enzymatic dissociation methods preferable for an analysis of the TIME in these tissues. Comparing several different enzymatic approaches, i.e. the Miltenyi “Tumor dissociation kit, human” (TDK), a cold protease- and a liberase TL (Roche)-mediated digestion, showed that cold protease treatment is also not optimal, as relatively few immune cells were recovered. Both TDK- and liberase TL-based digestion methods yielded similar amounts of immune cells with slight differences in their relative abundance.
Notes:
Based on our findings, we recommend that researchers interested in analysing the TIME in human brain metastasis tissue should first evaluate and compare various dissociation methods, in order to optimise the recovery of distinct cell populations depending on their specific research question. To standardize voltage settings across samples acquired on different days, single stained controls were included. Voltages were adjusted such that fluorescence intensity was identical for each antibody, regardless of date of acquisition (using defined acquisition settings and running CS&T beads on each day that samples were acquired). To account for biological variability, we analysed four different brain metastasis patient samples.