**5. Future perspectives**

208 Technical Problems in Patients on Hemodialysis

disease (2 patients), primary amyloidosis (1 patient), renal artery stenosis (1 patient), renal transplantation (1patient), and unknown causes (3 patients).The study was designed to compare high-flux (n=37) vs. low-flux (n=15) and polysulfone (n=42) vs. modified cellulose (n=10) membranes, seven different membranes were used: Arylane H, Tricea 210, HF-80, Arylane M6, FX-60, FX-80, and P160. The effect of the dialysis length on cfDNA

Although correct interpretation of the results is difficult with regard to many variable factors, cfDNA levels increased more than four-fold in 75% of the patients after HD. The study by García-Moreira et al. (2006) has two priorities: 1/ the real-time PCR method was used for the first time to quantify cfDNA; 2/ clear data about the clearance of elevated cfDNA concentrations after HD were provided to scientific community. The authors reported a rapid

In our study (Korabecna et al., 2008), we determined not only pre- and post-dialytic cfDNA concentrations in patients on hemodialysis (n=17) but we also examined non-dialyzed patients with chronic kidney disease (n=20) and patients on peritoneal dialysis (n=18) in comparison with healthy volunteers (n=20). We measured the total cfDNA levels using realtime PCR on GADPH gene. All patients involved in our study were hemodialyzed on high-

In HD patients, we found elevated postdialytic cfDNA values and reported high interindividual variability. We found also patients with lowered cfDNA values after hemodialysis. The levels of cfDNA in HD patients in pre-dialytic interval were significantly increased when compared with patients with chronic kidney disease and patients on peritoneal dialysis but there was no significant difference in comparison with healthy persons probably due to the very broad range of cfDNA concentrations obtained

It seems that the study of quantitative and qualitative cfDNA parameters with regard to the process of hemodialysis can bring very interesting insights into the biological aspect of the

In our study mentioned above (Korabecna et al., 208), we use real-time PCR based on the GAPDH gene sequence amplification for quantification of cfDNA in plasma and overnight dialysate in patients on peritoneal dialysis. We determined the ratio of dialysate cfDNA/plasma cfDNA (P/D ratio) and discovered that this ratio inversely correlates with the duration of period for which the person is treated by peritoneal dialysis. The values of P/D ratio lower than one were found in patients dialysed for longer time (median 17

Ozkaya et al. (2009) studied the plasma cfDNA in children on peritoneal dialysis and found significantly elevated values in comparison to healthy children and positive

Samples of peritoneal effluent with regard to their content of cfDNA were examined in the study by Pajek et al. (2009) to analyze the impact of PD solution with different biocompatibility and cytotoxic properties on the peritoneal membrane cells. Two PD solutions were tested: a conventional lactate buffered, acidic solution and a novel, bicarbonate/lactate buffered, neutral solution low in glucose degradation products. A significant decrease in appearance of

decline to normal values within 30 minutes of completing a hemodialysis session.

concentration after HD was evaluated.

flux polysulfone membrane.

in our control group.

months).

treatment with important clinical consequences.

**4.2 Cell-free nucleic acids in patients on peritoneal dialysis** 

correlation with C- reactive protein levels in treated children.

cfDNA in effluent was observed with the novel PD solution.

The study of cell-free nucleic acids in connection with hemodialysis promises new clinically important findings. Application of new methods – mainly the technology of Next Generation Sequencing (NGS) in combination with bionformatics – will bring huge amount of qualitative and quantitative data and allow the study of tiny fractions of specific sequences on the total circulating nucleic acids background. Recently, no studies focused on analysis of microRNA and mRNA in the plasma of hemodialyzed patient are available. Probably, such studies will be managed in near future.

It has been reported that some interleukins are generated during hemodialysis. It is known that activated monocytes during HD liberate certain mediators of immune response (Kim et al., 2011) therefore the study of individual mechanisms of immune response in patients may be very helpful in the process of individualized treatment. Insights into the current character of immune response can be achieved through the analysis of the methylation status of selected genes using existing arrays technologies. Such high throughput technologies will lead to the comparison of hemodialysis effects on the character of immune response in different groups of patients with different comorbidities.

DNA methylation patterns determined at the level of cfDNA in hemodialyzed patiens may be predictive of response to specific drugs and drug combinations.

The clinical studies performed on hemodialyzed patients can also improve the theoretical knowledge about the clearance and turnover of circulating nucleic acids in connection to the regulatory functions of this extremely interesting class of molecules.
