Lysosomal Trapping (Lysosomotropism) Assay

Lysosomes are essential for the degradation of old organelles and engulfed microbes and also play a role in programmed cell death.

Lysosomotropic agents e.g., chloroquine, accumulate preferentially in the lysosomes of cells in the body.

These agents tend to have both lipophilic or amphiphilic compounds with basic moieties. Once inside the acidic environment of the lysosome, the drug becomes protonated and trapped in the organelle.

Trapping of drugs in the lysosome may be one mechanism leading to drug-induced phospholipidosis for cationic amphiphilic drugs (CAD).

Cyprotex’s lysosomal trapping service is a cell based assay which uses high content screening to identify both lysosomotropism and cytotoxicity according to a recently published method.



Figure 1. Representative high content screening images for cells treated with (A) vehicle control (B) 50 µM chloroquine (a lysosomotropic agent) and (C) 150 µM piroxicam (a non-lysosomotropic agent) over a 4 hr period. Drugs which are lysosomotropic such as chloroquine competitively inhibit uptake of the lysosomal dye into the lysosomes.


Figure 2. Graphical representation of lysosomal trapping data for chloroquine (a lysosomotropic agent) and piroxicam (a non-lysosomotropic agent). Chloroquine causes a concentration dependent decrease in lysosomal staining compared to vehicle control treated cells. No effect was observed for piroxicam. No cytotoxic effects were observed for either compound at the concentration range tested. Data represents mean of triplicate incubations ± standard deviation.