Downregulation of lysosomal trafficking in ARPE19 cells leads to decreased transfection efficiency at high passage

PURPOSE

ARPE19 cells are a commonly used cell culture model for the study of retinal pigment epithelial cell biology and pathologies. However, numerous studies have demonstrated that ARPE19 undergo morphologic, transcriptomic and genomic alterations over time and with increasing passage number. Herein, we explore the mechanisms underlying increased resistance to the delivery of exogenous genetic material via transfection in ARPE19 cells using mass spectrometry.

METHODS

ARPE19 cells (N=5 wells/reagent) were seeded in 6-well plates at passages 24 through 30. At 70% confluency an mCherry reporter construct was delivered via transfection using Lipofectamine 3000, Lipofectamine LTX, Lipofectamine Stem, or PEI (polyethylenimine) reagents. After 72 hours, transfection efficiency was quantified by fluorescence microscopy and flow cytometry. Mass spectrometry and immunofluorescence of ARPE19 cells were performed at passages 24 and 30 to evaluate altered protein synthesis and localization between passage numbers.

RESULTS

ARPE19 transfection showed a maximum transfection efficiency of 32.4% at P26 using Lipofectamine 3000 reagent. All lipofectamine based reagents demonstrated statistically significant decreases in transfection efficiency between passages 24 and 30. Mass spectrometry analysis revealed 18 differentially expressed proteins, including down-regulation of clathrin light chain B (CLTB) and legumain (LGMN) that was confirmed via immunofluorescence imaging, which indicated altered intracellular localization.

CONCLUSIONS

ARPE19 cells demonstrate passage number dependent changes in lipofectamine-based transfection efficiency. Mass spectrometry and immunofluorescence indicates the observed decrease in transfection efficiency involves the dysregulation of endocytosis and intracellular endolysosomal trafficking at later passages.

TRANSLATIONAL RELEVANCE

This study contributes to mounting evidence for changes in ARPE19 cell physiology with increasing passage number. This information is of value for the continued use of ARPE19 cells as a model system for RPE biology and the development of therapeutics.

Isolation, culture, and cryosectioning of primary porcine retinal pigment epithelium on transwell cell culture inserts

Primary culture and long-term maintenance of primary retinal pigment epithelium (RPE) is a useful model system for the study of ocular pathologies such as age-related macular degeneration. Here, we detail the steps for the isolation and long-term culture of primary porcine RPE. We also describe steps for cryoprotecting, cryosectioning, and interrogating with immunofluorescence and histochemistry RPE cells grown on transwell membranes. These techniques can be used in histological studies to detect sub-RPE deposits. For complete details on the use and execution of this protocol, please refer to Pilgrim et al., (2017).

A controlled comparative investigation of psychological treatments for chronic sleep-onset insomnia

A sample of physician-referred chronic insomniacs was randomly allocated to either progressive relaxation, stimulus control, paradoxical intention, placebo or no treatment conditions. Treatment process and outcome were investigated in terms of mean and standard deviation (night to night variability) measures of sleep pattern and sleep quality. Only active treatments were associated with significant improvement, but the nature of treatment gains varied. In particular, stimulus control improved sleep pattern, whereas relaxation affected perception of sleep quality. All improvements were maintained at 17 month follow-up. Results are discussed with reference to previous research and guidelines are given for clinical practice.

A controlled trial of treatments for generalized anxiety

Treatments for chronic anxiety have received considerable interest recently. Firstly, there is a body of research which has shown problems of dependence and habituation in the long-term use of anti-anxiety drugs. A second development is that of psychological treatments for anxiety. Because of the problems involved in the use of benzodiazepines, it is important to determine whether or not psychological treatments are a reasonable alternative when treating chronic anxiety. This study was designed to test the relative effectiveness of cognitive-behavioural therapy, anxiety management training and treatment by benzodiazepines against a waiting list control. Measures were taken on both the process and outcome of treatment. The most immediate and greatest improvements in anxiety were seen in the group receiving drugs. However, these improvements reduced as the trial progressed and were minimal at the end of therapy. Both psychological treatment groups improved as the trial progressed with the most significant and consistent changes seen in the cognitive-behaviour therapy group. However, at follow-up there was no difference between the two groups receiving psychological treatments. Because of their lack of sustained improvement, over half of the group receiving drugs refused to wait without treatment until the follow-up assessment.