A method for quantifying cellular uptake of fluorescently labeled siRNA.

Area of Science:

• Biotechnology
• Molecular Biology
• Drug Delivery Systems

Background:

• Efficient intracellular delivery of small interfering RNA (siRNA) remains a significant challenge for its therapeutic applications.
• Accurate quantification of internalized siRNA is essential for evaluating carrier-mediated uptake efficiency in biological studies.

Purpose of the Study:

• To investigate discrepancies in apparent siRNA uptake measurements caused by quenching effects.
• To develop a reliable method for quantifying intracellular siRNA delivery, overcoming limitations of existing techniques.

Main Methods:

• Formulation of fluorescently labeled siRNA in various lipo- and polyplexes.
• Examination of siRNA uptake using different measurement techniques.
• Analysis of quenching phenomena influenced by siRNA-carrier interactions and intracellular environment.
• Development and validation of a cell lysis method with SDS to dissociate siRNA for accurate fluorescent signal measurement.

Main Results:

• Observed significant differences in apparent siRNA uptake depending on the measurement technique used.
• Identified quenching phenomena, dependent on siRNA-carrier interactions and intracellular conditions, as the cause of signal variations.
• Demonstrated that cell lysis in 2% SDS effectively dissociates siRNA from complexes, eliminating quenching effects.
• Validated a simple and accurate method for quantifying cellular siRNA uptake.

Conclusions:

• Quenching significantly impacts the accuracy of siRNA uptake measurements, particularly with fluorescently labeled siRNA complexed with carriers.
• A straightforward cell lysis protocol using SDS provides a robust approach to quantify intracellular siRNA delivery.
• This method facilitates the development and optimization of more efficient siRNA delivery systems for therapeutic and research purposes.