Photo-translocation of antiretroviral drugs into HIV-1 permissive cell lines

Abstract

Photo-translocation makes use of laser light to translocate exogenous materials into cells. It’s applicability as a drug delivery systems (DDS) has not been explored. This proof-of-principle study evaluated the applicability of a home-built femtosecond (fs)-laser based photo-translocation system as a DDS, using human immunodeficiency virus type-1 (HIV-1) antiretroviral (ARV) drugs as a model. A tightly focused pulsed laser was integrated into a photo-translocation system which was set up, validated and used to facilitate the delivery of ARV drugs against a concentration gradient into TZM-bl cells. To ensure preservation of the cell’s integrity, cell viability tests were carried out post laser treatment. An HIV-1 subtype C envelope-pseudovirus (ZM53) was generated and used in an in vitro phenotypic inhibition assay to measure the success of photo-translocation of three selected ARV drugs into TZM-bl cells. The near infrared (NIR) photo-translocation setup was successfully assembled and validated, as shown by characterisation of the relevant parameters such as pulse duration (10 picoseconds), central wavelength (1063.8 nm) and beam quality (1.15). The optimal functionality of the newly built photo-translocation system, as determined by trypan-blue exclusion dye in TZM-bl cells, was 3 doses of laser treatment at a power level of 60 mW and an exposure time of 50 ms. These parameters were extrapolated to photo-translocation experiments using selected ARV drugs. Photo-translocation of tenofovir and nevirapine resulted in enhanced levels of approximately 25% viral inhibition against ZM53 pseudoviruses. By contrast, no detectable change in viral inhibition was observed in the photo-translocation of efavirenz. Cell viability results confirmed that no toxicity existed within the laser irradiated cell population with cell viabilities greater than 70% at the tested drug concentrations. Tenofovir was not toxic to the cells at the administered concentration of 20 μg/ml. However, nevirapine (10 μg/ml) and efavirenz (14 μg/ml) showed high levels of toxicity after prolonged exposure to the cells (48 hours) while laser irradiation and brief (30 minutes) exposure to the drugs resulted in significant elevations of cell viability. Overall, this study demonstrated for the first time that laser technology is an efficient, targeted DDS which led to elevated therapeutic effects of ARV drugs against HIV-1 pseudoviruses with minimal damage to the treated cells in vitro.