Active transmembrane drug transport in microgravity: a validation study using an ABC transporter model

Abstract

Microgravity has been shown to influence the expression of ABC (ATP-Binding Cassette) transporters in bacteria, fungi and mammals, but also to modify the activity of certain cellular components with structural and functional similarities to ABC transporters. Changes in activity of ABC transporters could lead to important metabolic disorders and undesired pharmacological effects during spaceflights. However, no current means exist to study the functionality of these transporters in microgravity. To this end, a Vesicular Transport Assay ® (Solvo Biotechnology, Hungary) was adapted to evaluate multi-drug resistance-associated protein 2 (MRP2) trans-membrane estradiol-17-β-glucuronide (E17βG) transport activity, when activated by adenosine-tri-phosphate (ATP) during parabolic flights. Simple diffusion, ATP-independent transport and benzbromarone inhibition were also evaluated. A high accuracy engineering system was designed to perform, monitor and synchronize all procedures. Samples were analysed using a validated high sensitivity drug detection protocol. Experiments were performed in microgravity during parabolic flights, and compared to 1g on ground results using identical equipment and procedures in all cases. Our results revealed that sufficient equipment accuracy and analytical sensitivity were reached to detect transport activity in both gravitational conditions. Additionally, transport activity levels of on ground samples were within commercial transport standards, proving the validity of the methods and equipment used. MRP2 net transport activity was significantly reduced in microgravity, so was signal detected in simple diffusion samples. Ultra-structural changes induced by gravitational stress upon vesicle membranes or transporters could explain the current results, although alternative explanations are possible. Further research is needed to provide a conclusive answer in this regard. Nevertheless, the present validated technology opens new and interesting research lines in biology and human physiology with the potential for significant benefits for both space and terrestrial medicine.

Identification of Reference Genes in Human Myelomonocytic Cells for Gene Expression Studies in Altered Gravity

“…Altered expression levels of those genes by microgravity or hypergravity could have an impact on the translational level or the supply of the cell with essential resources important for proper cellular function. Recently it was shown that during parabolic flights the activity of the MRP2-ABC-transporter was significantly reduced [ 82 ]. Furthermore, under short duration spaceflight missions certain ABC transporter genes in the medically relevant species Salmonella sp.…”

Three Dimensional Printing (3DP) for Space Pharmaceuticals

“…In a recent investigation, alteration in lipid metabolism homeostasis as a result of an increased in hepatic triglyceride was reported during spaceflight (Jonscher et al 2016). Also, genetic expression of ATP-binding cassette transporters (Vaquer et al 2014) and activity of some transmembrane proteins and ion channels (Goldermann and Hanke 2001) have been reported to alter in actual and simulated microgravity conditions. Summarily, these changes could result in changes in drug metabolism which could either decrease or increase drug exposure significantly during spaceflight.…”

Ergonomic Challenges for Astronauts during Space Travel and the Need for Space Medicine

“…There have been a number of excellent publications either as reviews [1,[82][83][84][85][86][87][88][89] or as original research, including publications which illustrate the effect of gravity on drug targets, processes which affect drug behavior in physiological systems [72,73,86,[89][90][91][92][93][94][95][96][97][98][99][100][101][102][103][104] and this section will summarise the major findings. When planning astronaut healthcare for a space mission, there are a number of basic considerations which are, in part dependent upon the duration of the mission;…”

“…All drugs administered were associated with adverse events which were manageable and most reports of drug ineffectiveness were reported after the first day of administration. Although there was a paucity of available information on drug effectiveness, these early findings stimulated investigation into understanding pharmacokineticpharmacodynamic relationships and whether the space environment per se may effect drug properties such as stability [83,[88][89][90]94,[101][102][103][104][106][107][108]. To date, there have been two published studies which have investigated the effect of space flight on the pharmacokinetics of the analgesic acetaminophen [paracetamol] [91,109] and a further study investigating the same parameters of the stimulant dextroamphetamine and the anti-emetic scopolamine [92].…”