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Lofthouse EM, Cleal J, Lewis RM, Sengers BG. Computational Modelling of Paracellular Diffusion and OCT3 Mediated Transport of Metformin in the Perfused Human Placenta. J Pharm Sci 2023; 112:2570-2580. [PMID: 37211316 DOI: 10.1016/j.xphs.2023.05.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 05/15/2023] [Accepted: 05/15/2023] [Indexed: 05/23/2023]
Abstract
Metformin is an antidiabetic drug, increasingly prescribed in pregnancy and has been shown to cross the human placenta. The mechanisms underlying placental metformin transfer remain unclear. This study investigated the roles of drug transporters and paracellular diffusion in the bidirectional transfer of metformin across the human placental syncytiotrophoblast using placental perfusion experiments and computational modelling. 14C-metformin transfer was observed in the maternal to fetal and fetal to maternal directions and was not competitively inhibited by 5 mM unlabelled metformin. Computational modelling of the data was consistent with overall placental transfer via paracellular diffusion. Interestingly, the model also predicted a transient peak in fetal 14C-metformin release due to trans-stimulation of OCT3 by unlabelled metformin at the basal membrane. To test this hypothesis a second experiment was designed. OCT3 substrates (5 mM metformin, 5 mM verapamil and 10 mM decynium-22) added to the fetal artery trans-stimulated release of 14C-metformin from the placenta into the fetal circulation, while 5 mM corticosterone did not. This study demonstrated activity of OCT3 transporters on the basal membrane of the human syncytiotrophoblast. However, we did not detect a contribution of either OCT3 or apical membrane transporters to overall materno-fetal transfer, which could be represented adequately by paracellular diffusion in our system.
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Affiliation(s)
- Emma M Lofthouse
- Faculty of Medicine, University of Southampton, UK; Institute for Life Sciences, University of Southampton, UK
| | - Jane Cleal
- Faculty of Medicine, University of Southampton, UK; Institute for Life Sciences, University of Southampton, UK
| | - Rohan M Lewis
- Faculty of Medicine, University of Southampton, UK; Institute for Life Sciences, University of Southampton, UK
| | - Bram G Sengers
- Faculty of Engineering and Physical Sciences, University of Southampton, UK; Institute for Life Sciences, University of Southampton, UK.
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Cooke LDF, Tumbarello DA, Harvey NC, Sethi JK, Lewis RM, Cleal JK. Endocytosis in the placenta: An undervalued mediator of placental transfer. Placenta 2021; 113:67-73. [PMID: 33994009 DOI: 10.1016/j.placenta.2021.04.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Revised: 04/21/2021] [Accepted: 04/27/2021] [Indexed: 12/16/2022]
Abstract
Endocytosis is an essential mechanism for cellular uptake in many human tissues. A range of endocytic mechanisms occur including clathrin-dependent and -independent mechanisms. However, the role of endocytosis in the placenta and the spatial localisation of individual mechanisms is not well understood. The two principal cell layers that comprise the placental barrier to maternal-fetal transfer are the syncytiotrophoblast and fetal capillary endothelium. Endocytic uptake into the syncytiotrophoblast has been demonstrated for physiological maternal molecules such as transferrin-bound iron and low density lipoprotein (LDL) and may play an important role in the uptake of several other micronutrients, serum proteins, and therapeutics at both major placental cell barriers. These mechanisms may also mediate placental uptake of some viruses and nanoparticles. This review introduces the mechanisms of cargo-specific endocytosis and what is known about their localisation in the placenta, focussing predominantly on the syncytiotrophoblast. A fuller understanding of placental endocytosis is necessary to explain both fetal nutrition and the properties of the placental barrier. Characterising placental endocytic mechanisms and their regulation may allow us to identify their role in pregnancy pathologies and provide new avenues for therapeutic intervention.
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Affiliation(s)
- Laura D F Cooke
- The Institute of Developmental Sciences, University of Southampton, Southampton General Hospital, Southampton, SO16 6YD, UK.
| | - David A Tumbarello
- Biological Sciences, Faculty of Environmental and Life Sciences, University of Southampton, Highfield Campus, Life Sciences Building 85, Southampton, SO17 1BJ, UK
| | - Nicholas C Harvey
- MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton General Hospital, Southampton, SO16 6YD, UK; NIHR Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK
| | - Jaswinder K Sethi
- The Institute of Developmental Sciences, University of Southampton, Southampton General Hospital, Southampton, SO16 6YD, UK; NIHR Southampton Biomedical Research Centre, University of Southampton and University Hospital Southampton NHS Foundation Trust, Southampton, SO16 6YD, UK; Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
| | - Rohan M Lewis
- The Institute of Developmental Sciences, University of Southampton, Southampton General Hospital, Southampton, SO16 6YD, UK; Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
| | - Jane K Cleal
- The Institute of Developmental Sciences, University of Southampton, Southampton General Hospital, Southampton, SO16 6YD, UK; Institute for Life Sciences, University of Southampton, Southampton, United Kingdom
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