Purpose In the present study, silica nanoparticles (sNP) coupled with insulin-like growth factor 1 (IGF-1) were loaded on a collagen-based scaffold intended for cartilage repair, and the influence on the viability, proliferation, and differentiation potential of human primary articular chondrocytes was examined. Methods Human chondrocytes were isolated from the hyaline cartilage of patients (n=4, female, mean age: 73±5.1 years) undergoing primary total knee joint replacement. Cells were dedifferentiated and then cultivated on a bioresorbable collagen matrix supplemented with fluorescent sNP coupled with IGF-1 (sNP–IGF-1). After 3, 7, and 14 days of cultivation, cell viability and integrity into the collagen scaffold as well as metabolic cell activity and synthesis rate of matrix proteins (collagen type I and II) were analyzed. Results The number of vital cells increased over 14 days of cultivation, and the cells were able to infiltrate the collagen matrix (up to 120 μm by day 7). Chondrocytes cultured on the collagen scaffold supplemented with sNP–IGF-1 showed an increase in metabolic activity (5.98-fold), and reduced collagen type I (1.58-fold), but significantly increased collagen type II expression levels (1.53-fold; P =0.02) after 7 days of cultivation compared to 3 days. In contrast, chondrocytes grown in a monolayer on plastic supplemented with sNP-IGF-1 had significantly lower metabolic activity (1.32-fold; P =0.007), a consistent amount of collagen type I, and significantly reduced collagen type II protein expression (1.86-fold; P =0.001) after 7 days compared to 3 days. Conclusion Collagen-based scaffolds enriched with growth factors, such as IGF-1 coupled to nanoparticles, represent an improved therapeutic intervention for the targeted and controlled treatment of articular cartilage lesions.
Hemofilters applied in continuous renal replacement therapies (CRRTs) for the treatment of acute kidney injury must meet high standards in biocompatibility and permeability for middle and large molecules over extended treatment times. In general, cellulose-based membranes exhibit good biocompatibility and low fouling, and thus appear to be beneficial for CRRT. In this in vitro study, we compared a novel asymmetric cellulose triacetate (ATA) membrane with three synthetic membranes [polysulfone (PS), polyethersulfone (PES), and polyethylenimine-treated acrylonitrile/sodium methallyl sulfonate copolymer (AN69 ST)] regarding thrombogenicity and cytokine removal. For thrombogenicity assessment, we analyzed the thrombin-antithrombin complex (TAT) generation in human whole blood during 5 h recirculation and filtration. Sieving coefficients of interleukin-6 (IL-6), IL-8, IL-10, and tumor necrosis factor-alpha (TNF-α) were determined using human plasma as test fluid. ATA and AN69 ST membrane permeability were determined also during long-term experiments (48.5 h). ATA exhibited the lowest TAT generation (6.3 µg/L at 5 h), while AN69 ST induced a pronounced concentration increase (152.1 µg/L) and filter clogging during 4 out of 5 experiments. ATA (IL-8: 1.053; IL-6: 1.079; IL-10: 0.898; TNF-α: 0.493) and PES (0.973; 0.846; 0.468; 0.303) had the highest sieving coefficients, while PS (0.697; 0.100; 0.014; 0.012) and AN69 ST (N/A; 0.717; 0; 0.063) exhibited lower permeability. Long-term experiments revealed stronger fouling of the AN69 ST compared to the ATA membrane. We observed the highest permeability for the tested cytokines, the lowest thrombogenicity, and the lowest fouling with the ATA membrane. In CRRT, these factors may lead to increased therapy efficacy and lower incidence of coagulation-associated events.
Introduction: Continuous renal replacement therapies (CRRTs) are essential in the treatment of critically ill patients with acute kidney injury and are also discussed as a supporting sepsis therapy. CRRT can affect antibiotics plasma concentrations. Objective: The effect of continuous venovenous hemofiltration (CVVH) with an asymmetric triacetate (ATA) membrane hemofilter on concentrations of antibiotics with low (meropenem), medium (vancomycin), and high (daptomycin) protein binding (PB) was investigated. Methods: 1 L human whole blood supplemented with antibiotics was recirculated and filtrated for 6 h in vitro. Clearances and sieving coefficients (SC) were determined from antibiotics concentrations measured at filter inlet, outlet, and filtrate side. Reservoir concentration data were fitted using a first-order kinetic model. Results: Meropenem and vancomycin concentrations decreased to 5–10% of the initial plasma level, while only 50% of daptomycin were removed. Clearances and SCs were (10.8 [10.8–17.4] mL/min, SC = 0.72 [0.72–1.16]) for meropenem, (13.4 [12.3–13.7] mL/min, 0.89 [0.82–0.92]) for vancomycin, and (2.1 [1.8–2.1] mL/min, 0.14 [0.12–0.14]) for daptomycin. Removal by adsorption was negligible. Conclusions: The clearances and SCs presented are comparable with findings of other authors. Meropenem and vancomycin, which exhibit low and medium PB, respectively, were strongly removed, while considerably less daptomycin was removed because of its high PB. Our results suggest that in clinical use of the tested antibiotics during CRRT with the ATA hemofilter, the same factors have to be considered for determining the dosing strategy as with filters with other commonly applied membrane materials.
Background and Aims The removal of inflammatory mediators and cytokines is of great importance in the treatment of patients with acute or chronic renal failure. In patients with acute renal failure and sepsis, an attempt is made to achieve removal through the use of high-volume treatments or adsorbers in order to achieve better circulatory stability. In chronic dialysis patients, this has so far not been sufficiently addressed, but is important for mortality and cardiovascular events (MIA syndrome). Some studies show a superiority of HDF over conventional HD. By using new MCO filters in HD mode such as the Baxter Theranova (HDx), an improvement of cytokine status seems to be possible in both areas (chronic and acute). The effectiveness of MCO filters (HDx) compared to high flux hemodiafiltration in the removal of interleukins (interleukin 6, interleukin 10 and TNF (tumor necrosis factor) alpha will be assessed. Method The efficacy of HDx was compared with that of conventional high-flux dialysis filters (Fresenius FX80, HDF) in HDF mode. Based on real world conditions the ultrafiltration/substitution rate was set to 50 ml/min. (blood flow 200 ml/min., dialysate flow 500 ml/min.) No effective ultrafiltration was used. The measurements were performed in vitro in a 3l pool of fresh frozen plasma (citrate anticoagulated, with additional heparin during dialysis treatment). IL6 (24.5 kDa) IL10 (18.6 kDa, dimer)) and TNFalpha (17.4 kDa, trimer) were added to the plasma pool in concentrations of 1.5 μg/l each. This results in very high cytokine levels, as for example in severe sepsis. Samples were taken before and after the dialyzer for 180 minutes (after 5, 15, 30, 60, 120 and 180 minutes).For HDF the measured cytokine concentration was corrected for ultrafiltration rates. In addition to cytokines, albumin and total protein concentration were measured (ELISA Kit LEGEND MAX Human IL-6 / IL-10 / TNF-α; Biolegend and Cobas Mira Plus; Roche Kit LT-AB 0103 and LT-TP 0253). Every test was repeat 5 times. Results Theranova HDx showed higher removal rates of all tested cytokines over a period of 180 minutes. A comparison of the concentrations at the beginning and end of the measurements showed: IL-6 reduction - HDx about 77% / HDF about 63%. IL-10 reduction - HDx about 53% and HDF about 22%. TNF-α Reduction - HDx about 26%; HDF about 18% The concentration of albumin and total serum protein was not significant different during the treatments in both groups. Conclusion Hemodialysis therapy with Theranova HDx appears to be a superior or equal therapy option for the removal of cytokines. This opens up new treatment options for both acute renal failure and chronic dialysis patients, especially if citrate anticoagulation is necessary. The ultrafiltration rate in HDF was lower than recommended for high volume diafiltration,but as high as in our real world experience. Therefore the effect of HDF could be underestimated. Clinical studies with clinically relevant blood flow and ultrafiltration rates are still necessary.
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