Effects of conventional and new peritoneal dialysis solutions on human peritoneal mesothelial cell viability and proliferation

Objective: To investigate the biocompatibility of "new" peritoneal dialysis (PD) solutions with bicarbonate/lactate buffer, non glucose osmotic agents (icodextrin or amino acids), neutral pc, and tow levels of glucose degrada tion products (GDPs). Design: Using M199 culture medium as a control, we compared conventional an d new PD solutions with respect to their effects on the viability of human peritoneal mesothelial cells (HPMCs) [using lactate dehydrogenase (LDH) rel ease], on DNA damage in HPMCs [using single-cell gel electrophoresis (Comet assay)], and on HPMC proliferation (using [H-3]-thymidine incorporation). The experiments were performed after cell growth was synchronized by incuba tion with serum-free media for 24 hours. The PD solutions tested included c ommercial 1.5% glucose and 4.25% glucose solutions with 40 mmol/L lactate ( D 1.5 and D 4.25, respectively), 7.5% icodextrin (E), 1.1% amino acid (N), 1.5% glucose solution in a triple-chambered bag (Bio 1.5), 1.5% glucose sol ution in a dual-chambered bag with neutral pH (Bal 1.5), and 1.5% glucose a nd 4.25% glucose solution containing 25 mmol/L bicarbonate and 15 mmol/L la ctate (P 1.5 and P 4.25, respectively). Results: When HPMCs were continuously exposed to undiluted PD solutions, D 1.5, D 4.25, P 4.25, and E increased LDH release by more than 60% at 24 hou rs. All PD solutions tested increased LDH release by more than 75% at 96 ho urs. With a-fold diluted PD solutions, only D 4.25 significantly increased LDH release at 96 hours, though not at 24 hours. When cells were exposed to undiluted PD solutions for 60 min and allowed to recover in M199 for up to 96 hours, LDH release was significantly higher at 24 - 96 hours in E (55% - 69%) and D 1.5 (48% - 72%) as compared with control [M199 (18%)]. Release of LDH was significantly lower with PD solutions containing lower levels o f GDPs than those in D 1.5, suggesting that GDPs may have a role in cell vi ability. The D solutions (D 1.5 and D 4.25) and E solution also induced sig nificant DNA damage. Both LDH release and DNA damage by D and E were signif icantly attenuated by adjusting the solution pc to 7.4, suggesting that low pc may be implicated in PD solution-induced DNA damage and cell death. Whe n diluted 2-fold, D 1.5, D 4.25, and P 4.25 decreased [H-3]-thymidine incor poration to 43%, 34%, and 41% of control, respectively, at 24 hours and to 45%, 26%, and 35% of control, respectively, at 96 hours. When cells were ex posed to undiluted PD solutions for 5 minutes and allowed to recover in M19 9 for up to 96 hours, D 1.5 and P 4.25-but not D 4.25-significantly inhibit ed cell proliferation at 24 hours. This effect was sustained up to 96 hours . Conclusions:The present in vitro data demonstrate that PD solutions with lo w pc, or high levels of GDPs, or both, promote HPMC death and DNA damage, a nd that PD solutions with high osmolality inhibit cell proliferation. Solut ions with neutral pc, amino acids, and "low GDPs" appear to be more biocomp atible than conventional PD solutions. These results require confirmation i n in vivo animal and clinical studies.