Basic science: Genes encoding bile acid, phospholipid and anion transporters are expressed in a human fetal cardiomyocyte culture

Abstract

Objectives To establish a human fetal cardiomyocyte culture and to investigate whether the genes that encode transporters that may influence influx or efflux of bile acids are expressed in human fetal cardiomyocytes. Design Laboratory study. Setting Imperial College London. Sample Six fetal hearts were obtained at the time of termination of pregnancy at 12–13 weeks of gestation and used to generate primary human cardiomyocyte cultures. Methods To confirm the presence of cardiomyocytes, the cells were incubated with monoclonal antibodies to sarcomeric α‐actinin and anticardiac myosin heavy chain. Real‐time reverse transcription polymerase chain reaction was used to establish whether transcripts of genes that may influence bile acid transport are present in the culture (NTCP, BSEP, MDR3, FIC1, MRP2, MRP3, OATP‐A, OATP‐C, OATP‐D, OATP‐E) and whether taurocholate administration alters messenger RNA (mRNA) expression. Main outcome measures Relative mRNA expression of genes of interest. Results Real‐time polymerase chain reaction demonstrated the presence of mRNA for BSEP, MDR3, FIC1, OATP‐C, OATP‐D and OATP‐E in fetal heart. Four transcripts remained in the cardiomyocyte culture (BSEP, MDR3, FIC1 and OATP‐D), and we demonstrated the influence of taurocholate on gene expression. Conclusions We have developed an in vitro model of the fetal heart that may be used for studies of the cardiac effect of endobiotics, e.g. bile acids, or of specific agents that may be used to treat the mother or fetus in pregnancy.

Systemic gut microbial modulation of bile acid metabolism in host tissue compartments

“…The global signaling capacity of bile acids is currently unclear; however, the expression of bile acid receptors FXR and TGR5 in tissues outside of the enterohepatic circulation, including the kidney (25) and heart (26,27), suggests a greater role throughout the body. Expression of bile acid transporters in renal tubular cells [Asbt (28), organic anion transporting polypeptide 1 (OATP1) (29), and kidney specific organic anion transporter (OATK2) (30)] and cardiomyocytes (31,32) further supports this proposition. Moreover, the involvement of bile acids in the regulation of glucose homeostasis is consistent with the expression of FXR in pancreatic β-cells, which has been shown to play an essential role in the regulation of insulin transcription and secretion induced by glucose (33).…”

“…Although the biological significance of bile acids in the heart remains to be elucidated, given their known function as signaling molecules and the presence of the FXR and TGR5 receptors in addition to bile acid transporters in the heart (26,27,31,32), it is feasible that bile acids serve a regulatory role in cardiomyocyte metabolism. A minor route of bile acid elimination is urinary excretion, removing excess bile acids from systemic circulation.…”

“…Additionally, it is known that the hepatic extraction of free bile acids is also less efficient compared with the conjugated forms (35), and this further explains the greater proportion of unconjugated bile acids in the systemic circulation and consequently, the kidney and heart. At physiological pH, conjugated bile acids are negatively charged and require carrier-mediated transport across tissue membranes; therefore, it is likely that these organspecific profiles arise from selective uptake caused by differential expression of bile acid transporters in the renal tubular cells and cardiomyocytes (28)(29)(30)(31)(32). In a previous study, Dupont et al (36) showed organ-specific differences in the ratios of glycine-and taurine-conjugated bile acids in a range of tissues from miniature swine using gas liquid chromatography.…”

The protective effect of ursodeoxycholic acid in an in vitro model of the human fetal heart occurs via targeting cardiac fibroblasts

“…Previous research in our lab focused on neonatal rat models of the fetal heart, although some work was previously carried out using isolated human fetal cardiomyocytes from aborted fetuses of 9 -12 weeks of gestation with no known pathology (Gorelik et al, 2006a). These cells were used to investigate gene expression of bile acid transporters and changes in expression after TC incubation (Gorelik et al, 2006a).…”

“…These cells were used to investigate gene expression of bile acid transporters and changes in expression after TC incubation (Gorelik et al, 2006a). …”