A Combination of Hemodialysis with Hemoperfusion Helped to Reduce the Cardiovascular-Related Mortality Rate after a 3-Year Follow-Up: A Pilot Study in Vietnam

Derivation and elimination of uremic toxins from kidney-gut axis

Uremic toxins are chemicals, organic or inorganic, that accumulate in the body fluids of individuals with acute or chronic kidney disease and impaired renal function. More than 130 uremic solutions are included in the most comprehensive reviews to date by the European Uremic Toxins Work Group, and novel investigations are ongoing to increase this number. Although approaches to remove uremic toxins have emerged, recalcitrant toxins that injure the human body remain a difficult problem. Herein, we review the derivation and elimination of uremic toxins, outline kidney-gut axis function and relative toxin removal methods, and elucidate promising approaches to effectively remove toxins.

Effect of different hemodialysis modalities on hepcidin clearance in patients undergoing maintenance hemodialysis

INTRODUCTION

Hepcidin is a master regulator of iron utilization and takes part in the pathophysiology of anemia in maintenance hemodialysis (MHD) patients. Hepcidin is a moderate-molecular-weight substance and partially binds to plasma proteins in the circulation, which theoretically might be removed efficiently by hemoperfusion (HP). This study aimed to compare the effect of different dialysis modalities on hepcidin removal and discuss its effect on the iron and anemia status in MHD patients.

MATERIALS AND METHODS

In a longitudinal interventional study of 26 stable MHD patients, the serum hepcidin, β2-microglobulin (β2-MG), and intact parathyroid hormone (iPTH) were measured before and after one treatment session of hemodialysis (HD), hemodiafiltration (HDF), HD + HP, and HDF + HP, separately. One-way analysis of variance (ANOVA) was used to identify the effect of dialysis modalities on the intra-dialysis clearance ratios.

RESULTS

The combined dialysis modalities (HD + HP and HDF + HP) achieved greater clearance ratios of serum hepcidin than HD and HDF alone, HD + HP vs. HD (16 ± 15% vs. 4 ± 13%, p < 0.001), HDF + HP vs. HDF (18 ± 5% vs. 10 ± 13%, p = 0.0036). Similarly, the combined dialysis modalities also performed better than HD and HDF alone in removing β2-MG. There was no significant difference in iPTH clearance among these four modalities, except that HDF + HP achieved a greater clearance ratio than HD. Furthermore, the anemia was improved after the 6-month treatment with regular HD/HDF plus HP, which was indicated by increasing hemoglobin (p = 0.0004) and reduction of erythropoiesis-stimulating agents (ESAs) resistance index (ERI) (p = 0.0431).

CONCLUSIONS

Our findings suggest that the combined dialysis modalities of HD/HDF plus HP could achieve better clearance ratios of hepcidin than HD/HDF alone, thereby, might improve iron utilization, and benefit anemia management in MHD patients. Further studies with larger sample-size patients and longer follow-up duration are still needed.

Comparative efficacy between hemodialysis using super high-flux dialyzer with hemoperfusion and high-volume postdilution online hemodiafiltration in removing protein bound and middle molecule uremic toxins: A cross-over randomized controlled trial

BACKGROUND

Hemodialysis (HD) using super high-flux dialyzer (HD + SHF) comparably removed uremic toxins to high-volume postdilution online hemodiafiltration (olHDF). Integration of hemoperfusion (HP) to HD + SHF (HD + SHF + HP) might provide superior uremic toxin removing capability to high-volume postdilution olHDF.

METHOD

The present study was conducted in thrice-a-week HD patients to compare the efficacy in removing indoxyl sulfate (IS), beta-2 microglobulin (β₂ M), and urea between high-volume postdilution ol-HDF and HD + SHF + HP, comprising HD + SHF as the main treatment plus HD + SHF + HP 1/week in the first 4 weeks and 1/2 weeks in the second 4 weeks.

RESULTS

Ten prevalent HD patients with blood flow rate (BFR) above 400 ml/min were randomized into two sequences of 8-week treatment periods of HD + SHF + HP and later high-volume postdilution olHDF or vice versa. When compared with high-volume postdilution olHDF (convective volume of 26.02 ± 1.8 L/session), HD + SHF + HP provided comparable values of percentage reduction ratio of IS (52.0 ± 11.7 vs. 56.3 ± 7.5%, p = 0.14) and β₂ M (83.7 ± 4.9 vs. 84.0 ± 4.3%, p = 0.37) and slightly lower urea reduction ratio. Despite greater dialysate albumin loss (p = 0.008), there was no significant change in serum albumin level in HD + SHF + HP group.

CONCLUSIONS

HD + SHF + HP could not provide superior efficacy in removing uremic toxins to high-volume postdilution olHDF. The use of low BFR of 200 ml/min during the first 2 h of HD + SHF + HP session, according to the instruction of manufacturer, might impair the efficacy of the HD + SHF part in removing uremic toxins.

Elimination of Uremic Toxins by Functionalized Graphene-Based Composite Beads for Direct Hemoperfusion

Conventional absorbents for hemoperfusions suffer from low efficiency and slow absorption with numerous side effects. In this research, we developed cellulose acetate (CA) functionalized graphene oxide (GO) beads (∼1.5-2 mm) that can be used for direct hemoperfusion, aiming at the treatment of kidney dysfunction. The CA-functionalized GO bead facilitates adsorption of toxins with high biocompatibility and high-efficiency of hemoperfusion while maintaining high retention for red blood cell, white blood cells, and platelets. Our in vitro results show that the toxin concentration for creatinine reduced from 0.21 to 0.12 μM (p < 0.005), uric acid from 0.31 to 0.15 mM (p < 0.005), and bilirubin from 0.36 to 0.09 mM (p < 0.005), restoring to normal levels within 2 h. Our in vivo study on rats (Sprague-Dawley, n = 30) showed that the concentration for creatinine reduced from 83.23 to 54.87 μmol L^-1 (p < 0.0001) and uric acid from 93.4 to 54.14 μmol L^-1 (p < 0.0001), restoring to normal levels within 30 min. Results from molecular dynamics (MD) simulations using free-energy calculations reveal that the presence of CA on GO increases the surface area for adsorption and enhances penetration of toxins in the binding cavities because of the increased electrostatic and van der Waals force (vdW) interactions. These results provide critical insight to fabricate graphene-based beads for hemoperfusion and to have the potential for the treatment of blood-related disease.