Mitochondrial metabolism in human fresh villous trophoblast

Abstract

Objectives: To study different metabolic parameters of the mitochondrialpopulation present in the villous trophoblast in the human termplacenta.Methods: This study was approved by the ethics committee of HospitalNacional Prof. Dr. A. Posadas. After fresh placental tissue dissection, differentialultracentrifugation, followed by flow cytometry analysis of theirForward Scatter (FSC) and Side Scatter (SSC) parameters were performed.Two different mitochondrial fractions were obtained and several mitochondrialmetabolic parameters were determined: transmembrane potential(Dym), cardiolipin content, activity of the mitochondrial respiratorycomplexes as well as the hydrogen peroxide production in both mitochondrialsubpopulations.Results: We could confirm the presence of two mitochondrial subpopulationsthat coexist in fresh human villous trophoblast, describedas heavy/large particles with high FSC and light/small particles with lowFSC, both with similar SSC characteristics. Analysis of the Dym showedthat the light/small mitochondria are more depolarized as comparedwith the large/heavy mitochondria subpopulations, with a level of polarization30% lower than the heavy mitochondrial samples. In addition,the mitochondrial cardiolipin level of the small population was lesserthan the observed in the heavy mitochondrial samples, showing 42% ofcardiolipin oxidation/depletion, probably due to an induced mitochondrialoxidative process.Conclusion: These results suggest that the mitochondrial population inthe human villous trophoblast could exhibit different morphologic andmetabolic states. Thus, the respiratory function closely associated to theiroxidative processes may regulate the energy demand critical for the progesteroneproduction and cell death process during trophoblast turnover.Consequently, alterations in the mitochondrial function of these subpopulationsmay be related to the aberrant differentiation in the villoustrophoblast observed in preeclampsia.