Cool temperature hemodialysis and biocompatibility in chronic hemodialysis patients: a preliminary study.

BACKGROUND: Cooler temperature dialysate (TD) has gained in popularity in the treatment of hypotension during hemodialysis (HD). In this study we verified the hypothesis of an eventual involvement of cytokines. METHODS: Four patients on regular HD underwent two 4-hour HD sessions once at 37 degrees C TD and once at 35 degrees C TD. The concentration of the cytokines (cyt) IL-1, IL-2, IL-8, IL-12 and tumor necrosis factor-alpha (TNF-alpha) was measured before the HD session initiation and after 20, 60, 120 and 240 minutes. Body temperature, weight, blood pressure and heart rate were registered at the same time points. RESULTS: We found a higher blood pressure at 35 degrees C but no intradialytic differences in cyt concentration at 35 degrees C or 37 degrees C. The percentage changes of cyt from baseline were very slight, except for IL-8 which decreased by 40% both at 35 degrees C and 37 degrees C. CONCLUSIONS: These preliminary results suggest that cytokines do not seem play a relevant role in determining the favorable effects of cooler TD on blood pressure. Our study is preliminary and our results need to be confirmed by other studies.

Parathyroid hormone and mobilization of circulating bone marrow-derived cells in uremic patients.

BACKGROUND: Parathyroid hormone (PTH) revealed a positive action on progenitor cells released from bone marrow, and many mechanisms supported PTH as a tool to improve stem cell-based therapy in experimental models of ischemia. Elevated PTH resulted in increased mobilization of progenitors into the peripheral blood of patients affected by untreated primary hyperparathyroidism. A frequent finding in uremic patients is a higher PTH level, and different therapeutic strategies are adopted and implemented to achieve an intermediary PTH level. On the contrary, the amount of progenitors commonly results to be extremely reduced. OBJECTIVE: In the present study, we investigated, in a cohort of uremic patients, the effect of different levels of PTH on mobilization of progenitor cell populations. METHODS: Eighty patients (26 women, 54 men) were enrolled. Following the Kidney Disease Outcomes Quality Initiative (KDOQI) guidelines, patients were divided in 3 groups for PTH levels: low-PTH group with a PTH level lower than 150 pg/mL (n = 25), KDOQI-PTH group with a PTH level between 150 and 300 pg/mL (n = 37), and high-PTH group with a PTH level higher than 300 pg/mL (n = 18). Patients with high levels of PTH were treated differently to achieve KDOQI targets: 5 received intravenous calcitriol and P binders, 3 received intravenous paracalcitriol, and 10 received cinacalcet. We quantified, by the combination of surface markers (CD45(+), CD34(+), CD31(+), and c-kit(+)), the number of hematopoietic and endothelial progenitor cells. RESULTS: High-PTH group demonstrated a significantly higher level of CD45(+)/CD34(+)/c-kit(+) with respect to low-PTH and KDOQI-PTH groups (1.02 [SD, 0.12] vs. 0.56 [SD, 0.14] cells/uL, P < 0.01; and 1.02 [SD, 0.12] vs. 0.46 [SD, 0.20] cells/uL, P < 0.05). CD45(+)/CD34(+)/CD31(+) levels resulted significantly increased in the KDOQI-PTH group compared with those observed in the low- (1.83 [SD, 0.72] vs 1.26 [SD, 0.83] cells/µL, P = 0.04) and high-PTH groups (1.83 [SD, 0.72] vs 1.20 [SD, 1.15] cells/µL, P = 0.04). Receiver operating characteristic analyses were performed to define the ability of CD45(+)/34(+)/31(+) to identify the presence of an optimal PTH status (>150 but <300 pg/mL) among all hemodialysis patients. The area under the curve of CD45(+)/34(+)/31(+) was 0.674 (95% confidence interval [CI], 0.501-0.819) with a best cutoff level of 1.36 cells/µL (sensitivity, 80.0; specificity, 59.1; P < 0.05). After 4 months, we demonstrated an increase in endothelial progenitor cell number in 13 patients with secondary hyperparathyroidism that achieved KDOQI targets in PTH levels after pharmacological treatment. CONCLUSIONS: Our data confirm, with acknowledged limitations due to the low number of patients, the effect of PTH on bone marrow-derived progenitor cells emphasizing that, in our cohort, an intermediary PTH level, achieved following specific guidelines, results in an equilibrate balance between different subsets of progenitor cells.