Efficient Adsorption of Tumor Necrosis Factor with an in vitro Set-Up of the Microspheres-Based Detoxification System

Dieter Falkenhagen (1942–2015): A Multifaceted Scientist

Dieter Falkenhagen was born in 1942 in Dresden, Germany and died in 2015. He specialized in internal medicine and nephrology. Focusing on artificial organ research, he investigated various aspects of the efficacy and safety of hemodialysis and adsorption technologies, including biocompatibility issues related to blood versus surface interactions and the adverse effects of endotoxin contamination. He studied various mathematical models to analyze efficacy and safety, and animal models to help clarify uncertainty issues. Through his studies, adsorbents were developed, resulting in Prometheus, an artificial liver support device. Anticoagulation models, including citrate perfusion, were improved and made safer by his work. He also stepped into bioreactor research to increase efficacy of liver support devices.

Techniques of extracorporeal cytokine removal: a systematic review of the literature

BACKGROUND AND AIMS

Attempts at achieving cytokine homeostasis include blood purification to deliver cytokine removal. Assessment of ex vivo studies for optimal operating conditions is a vital step.

METHODS

We conducted a systematic search for ex vivo studies on cytokine removal using known modalities of extracorporeal circulation. We selected 29 articles and analyzed data according to clearance, sieving coefficient, ultrafiltrate concentration and percentage removal.

RESULTS

We identified four main techniques for cytokine removal: standard techniques, high cut-off (HCO) techniques, adsorption techniques and combined plasma filtration adsorption. HCO hemofiltration (HCO/HF) showed greatest consistency in cytokine removal among all approaches. Mean albumin clearance with HCO filters was 3.74 ml/min.

CONCLUSION

Ex vivo data support the view that HCO/HF is the most consistently effective approach in terms of sieving and clearance. Further investigation of HCO/HF in randomized controlled trials in animal models and humans seems desirable.

Activation-dependent adsorption of cytokines and toxins related to liver failure to carbon beads

In the course of severe pathological conditions, such as acute liver failure and sepsis, toxic metabolites and mediators of inflammation are released into the patient's circulation. One option for the supportive treatment of these conditions is plasmapheresis, in which plasma, after being separated from the cellular components of the blood, is cleansed by adsorption of harmful molecules on polymers or activated carbon. In this work, the adsorption characteristics of activated carbon beads with levels of activation ranging from 0 to 86% were assessed for both hydrophobic compounds accumulating in liver failure (bilirubin, cholic acid, phenol and tryptophan) and cytokines (tumor necrosis factor α and interleukin-6). Progressive activation resulted in significant gradual reduction of both bulk density and mean particle size, in an increase in the specific surface area, and to changes in pore size distribution with progressive broadening of micropores. These structural changes went hand in hand with enhanced adsorption of small adsorbates, such as IL-6 and cholic acid and, to a lesser extent, also of large molecules, such as TNF-α.

Adsorptive modulation of inflammatory mediators dampens endothelial cell activation

AIM

In this study, the effect of specific or selective adsorption of inflammatory mediators on endothelial activation was assessed.

METHODS

Conditioned medium was obtained by stimulation of monocytic THP-1 cells with lipopolysaccharide and treated either with an adsorbent specific for tumour necrosis factor-α or with an albumin-coated polystyrene-divinylbenzene copolymer which selectively binds a range of cytokines. Thereafter, the conditioned medium was applied to endothelial cells in culture.

RESULTS

Adsorption of inflammatory mediators resulted in significantly decreased endothelial cell activation, as shown by reduced interleukin (IL)-6 and IL-8 secretion from endothelial cells as well as reduced surface expression of the adhesion molecules intercellular adhesion molecule-1 and E-selectin. The effect was more pronounced the earlier the mediator modulation was performed.

CONCLUSION

Adsorptive modulation of inflammatory mediators dampens endothelial cell activation and may thus be beneficial as supportive therapy in sepsis.

Safe and effective devices and instruments for use in the neonatal intensive care units: NICHD Workshop summary

The neonatal intensive care unit (NICU) depends heavily on advanced biomedical devices for monitoring, diagnosis, and treatment. Developing safe and effective devices for use in the NICU requires collaborative research and testing efforts between the bioengineering and biomedical disciplines. However, no mechanism exists to match the needs of the clinical community and the efforts of the bioengineering community. To address this issue, in February 2009, the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) of the National Institutes of Health (NIH) invited a team of experts from diverse fields of biomedicine and bioengineering to participate in a workshop. The team reviewed and summarized bioinstrumentation needs and proposed a research agenda to develop safe and effective devices and instruments. The discussants addressed topics in cardiopulmonary, cerebrovascular, metabolic, and infectious conditions of the neonate. The authors provide a summary of the workshop discussions in this paper.