title: Megalin expression in human term and preterm placental villous tissues: effect of gestational age and sample processing and storage time.
abstract: BACKGROUND
  The aims of this study were to characterize megalin expression in human term and preterm placental villous tissues and to assess the impact of gestational age and sample storage on receptor expression.
  
  
  METHODS
  Placental tissue samples were collected from pregnant women undergoing term and preterm Cesarean deliveries. Placental villous tissues were used to quantify megalin protein and mRNA expression by western blotting and quantitative polymerase chain reaction (q-PCR), respectively. Stability of megalin expression was also evaluated under various processing and storage conditions.
  
  
  RESULTS
  Megalin mRNA was detected in term and preterm placental villous tissues. Expression in early preterm samples was 6-fold higher than in late preterm and term samples. Refrigeration of processed term samples at 4°C for up to 18h had a slight impact on megalin mRNA expression with stored samples exhibiting mRNA levels approximately 1.5-fold lower than those frozen immediately after processing. A greater decrease in mRNA expression (up to 33-fold) was observed when processed samples were snap-frozen immediately and thawed at 4°C. Processing of samples prior to refrigeration also appeared to improve mRNA stability with significantly higher expression levels noted in processed vs. unprocessed samples at all points for up to 48h.
  
  
  CONCLUSIONS
  These data suggest that expression of megalin mRNA in term placental villous tissue is relatively stable for up to 18h when samples are processed immediately and refrigerated at 4°C prior to freezing. Processing prior to storage also appears to improve mRNA stability. This paper demonstrates the practical feasibility of analyzing stored tissue samples, thus, it will help with placental mRNA analysis. Additionally, megalin expression appears to vary inversely with gestational age with the greatest expression noted in the most premature samples. Age-dependent differences in placental megalin may therefore influence fetal exposure.
authors.affiliation: Department of Pharmacotherapy and Outcomes Science, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, United States.
authors.forename: Amal A
authors.initials: AA
authors.lastname: Akour
authors.affiliation: Department of Pharmaceutics, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, United States.
authors.forename: Phillip
authors.initials: P
authors.lastname: Gerk
authors.affiliation: Department of Pharmacotherapy and Outcomes Science, School of Pharmacy, Virginia Commonwealth University, Richmond, VA, United States. Electronic address: mjkennedy@vcu.edu.
authors.forename: Mary Jayne
authors.initials: MJ
authors.lastname: Kennedy
mesh_terms: D000293:Adolescent; D000328:Adult; D002460:Cell Line; D005260:Female; D005865:Gestational Age; D056945:Hep G2 Cells; D006801:Humans; D026561:Low Density Lipoprotein Receptor-Related Protein-2 / Q000235:genetics*; D008875:Middle Aged; D010920:Placenta / Q000378:metabolism*; D011247:Pregnancy; D012333:RNA, Messenger / Q000235:genetics; D013048:Specimen Handling; D013997:Time Factors; D014021:Tissue Preservation; D055815:Young Adult
chemical_list: D026561:Low Density Lipoprotein Receptor-Related Protein-2; D012333:RNA, Messenger
keywords: Megalin; Placenta; Preterm; Receptor-mediated endocytosis; mRNA stability