Influence of bicarbonate/low-GDP peritoneal dialysis fluid (BicaVera) on in vitro and ex vivo epithelial-to-mesenchymal transition of mesothelial cells.
BACKGROUND
Peritoneal membrane damage induced by peritoneal dialysis (PD) is largely associated with epithelial-to-mesenchymal transition (EMT) of mesothelial cells (MCs), which is believed to be a result mainly of the glucose degradation products (GDPs) present in PD solutions.


OBJECTIVE
This study investigated the impact of bicarbonate-buffered, low-GDP PD solution (BicaVera: Fresenius Medical Care, Bad Homburg, Germany) on EMT of MCs in vitro and ex vivo.


METHODS



METHODS
Omentum-derived MCs were incubated with lactate-buffered standard PD fluid or BicaVera fluid diluted 1:1 with culture medium. Ex vivo studies: From 31 patients randomly distributed to either standard or BicaVera solution and followed for 24 months, effluents were collected every 6 months for determination of EMT markers in effluent MCs.


RESULTS
Culturing of MCs with standard fluid in vitro resulted in morphology change to a non-epithelioid shape, with downregulation of E-cadherin (indicative of EMT) and strong induction of vascular endothelial growth factor (VEGF) expression. By contrast, in vitro exposure of MCs to bicarbonate/low-GDP solution had less impact on both EMT parameters. Ex vivo studies partially confirmed the foregoing results. The BicaVera group, with a higher prevalence of the non-epithelioid MC phenotype at baseline (for unknown reasons), showed a clear and significant trend to gain and maintain an epithelioid phenotype at medium- and longer-term and to show fewer fibrogenic characteristics. By contrast, the standard solution group demonstrated a progressive and significantly higher presence of the non-epithelioid phenotype. Compared with effluent MCs having an epithelioid phenotype, MCs with non-epithelioid morphology showed significantly lower levels of E-cadherin and greater levels of fibronectin and VEGF. In comparing the BicaVera and standard solution groups, MCs from the standard solution group showed significantly higher secretion of interleukin 8 and lower secretion of collagen I, but no differences in the levels of other EMT-associated molecules, including fibronectin, VEGF, E-cadherin, and transforming growth factor β1. Peritonitis incidence was similar in both groups. Functionally, the use of BicaVera fluid was associated with higher transport of small molecules and lower ultrafiltration capacity.


CONCLUSIONS
Effluent MCs grown ex vivo from patients treated with bicarbonate/low-GDP BicaVera fluid showed a trend to acquire an epithelial phenotype, with lower production of proinflammatory cytokines and chemokines (such as interleukin 8) than was seen with MCs from patients treated with a lactate-buffered standard PD solution.
Servicio de Nefrología, Unidad de Biología Molecular and Instituto de Investigación del Hospital Universitario de la Princesa, Madrid, Spain.
Antonio
A
Fernández-Perpén
María Luisa
ML
Pérez-Lozano
María-Auxiliadora
MA
Bajo
Patricia
P
Albar-Vizcaino
Pilar
P
Sandoval Correa
Gloria
G
del Peso
María-José
MJ
Castro
Abelardo
A
Aguilera
Marta
M
Ossorio
Mirjam E
ME
Peter
Jutta
J
Passlick-Deetjen
Luiz S
LS
Aroeira
Rafael
R
Selgas
Manuel
M
López-Cabrera
J Antonio
JA
Sánchez-Tomero
D001639:Bicarbonates / Q000032:analysis / Q000493:pharmacokinetics*; D002478:Cells, Cultured; D015314:Dialysis Solutions / Q000737:chemistry / Q000494:pharmacology*; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects*; D005947:Glucose / Q000032:analysis / Q000378:metabolism* / Q000494:pharmacology*; D006801:Humans; D010530:Peritoneal Dialysis
D001639:Bicarbonates; D015314:Dialysis Solutions; D005947:Glucose