Hydrodynamic analysis of the miniaturized hemofilter for a wearable ultrafiltration device.

BACKGROUND/AIMS: Using a small wearable hemofiltration device, heart failure (HF) patients may have the possibility of eliminating acute hemodynamic changes and the freedom from spending many hours attached to a large stationary treatment system. METHODS: We developed a miniaturized hemofilter for a vest-type wearable ultrafiltration device for the treatment of overhydration and congestive HF. In this study, we investigated the feasibility of the newly developed hemofilter based on dynamic CT imaging and in vitro evaluation of hydrodynamic properties. RESULTS: The dynamic CT imaging technique showed development of uniform flow distribution and effective bubble removal in the hemofilter. Hydrodynamic performance of the hemofilter was also acceptable with a stable pressure drop in the blood compartment and ultrafiltration profiles in the intended operating ranges for the treatment of congestive HF patients. CONCLUSIONS: The newly developed miniaturized hemofilter for a wearable ultrafiltration device meets the technical requirements of wearable medical devices and its structural design enables uniform blood flow distribution and stable hydrodynamics during operation.

Time-related analysis of metabolic liver functions, cellular morphology, and gene expression of hepatocytes cultured in the bioartificial liver of the Academic Medical Center in Amsterdam (AMC-BAL).

A comprehensive understanding of the mechanisms that underlie hepatic differentiation inside a bioartificial liver (BAL) device is obtained when functional, histological, and gene expression analyses can be combined. We therefore developed a novel cell-sampling technique that enabled us to analyze adherent hepatocytes inside a BAL device during a 5-day culture period, without the necessity of terminating the culture. Biochemical data showed that hepatocyte-specific functions were relatively stable, despite an increase in glycolytic activity. Quantitative reverse transcriptase polymerase chain reaction analysis of hepatic genes cytochrome p450 3A29, albumin, glutamine synthetase, alpha-1 antitrypsin, and carbamoyl-phosphate synthetase, but also de-differentiation marker pi-class glutathione S transferase showed stable messenger ribonucleic acid (mRNA) levels from day 1 to 5. In contrast, mRNA levels of alpha-fetoprotein, pro- and anti-apoptotic genes Bax-alpha and Bcl-X(L), metabolic genes lactate dehydrogenase and uncoupling protein 2, and cytoskeleton genes alpha- and beta-tubulin and beta-actin increased in 5 days. Histological analysis revealed viable tissue-like structures with adaptation to the in vitro environment. We conclude that hepatocytes show a tendency for de-differentiation shortly after seeding but thereafter remain acceptably differentiated during 5 days of culture. Furthermore, partly impaired mitochondrial function is suggestive for local hypoxic regions and may trigger the observed metabolic changes. Anti-apoptotic activity seems to balance pro-apoptotic activity. This new cell-sampling technique facilitates the analysis of dynamic processes of hepatocyte culture inside a BAL.