Stress-wave-assisted transport through the plasma membrane in vitro

Background and Objective: Laser-induced stress waves have been shown to alter the permeability of the plasma membrane without affecting cell viability. The aim of the work reported here was to quantify the molecular uptake by cell cultures in vitro and determine optimal stress-wave parameters. Study Design/Materials and Methods: Human peripheral blood mononuclear cells were exposed to laser-induced stress waves in an experimental arrangement that eliminated interference from ancillary effects such as plasma, heat, or cavitation. A radiolabeled compound (tritiated thymidine) was used as the probe. Results: Stress waves enhanced the diffusion of tritiated thymidine by inducing a transient permeabilization of the plasma membrane. Furthermore, maximum intracellular concentration (2 x 10⁵ thymidine molecules/cell or 10% of the extracellular concentration) was reached with only 2-3 stress waves. Conclusion: Laser-induced stress waves provide an efficient method for delivering molecules through the plasma membrane into the cytoplasm of cells.