In vitro cell culture systems as the basis for an extracorporeal blood purification strategy in multiorgan failure treatment

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.

The helix-loop-helix transcription factor TWIST is dysregulated in myelodysplastic syndromes

Patients with low-grade myelodysplastic syndromes (MDS) show high levels of tumor necrosis factor α (TNFα) and up-regulation of apoptosis in the marrow. In contrast, marrow cells in advanced MDS are typically resistant to TNFα-induced apoptosis but are rendered apoptosis-sensitive on coculture with stroma. The present studies show that CD34(+) marrow cells in advanced MDS express high levels of TWIST, a basic helix-loop-helix transcription factor that opposes p53 function. TWIST levels correlated with disease stage (advanced > low grade; P = .01). Coculture with HS5 stroma resulted in down-regulation of TWIST and increased apoptosis in response to TNFα in CD34(+) cells from advanced MDS; the same effect was achieved by TWIST-specific RNA interference in CD34(+) cells. In primary MDS marrow stroma TWIST expression was lower than in healthy controls; suppression of TWIST in stroma interfered with induction of apoptosis sensitivity in cocultured CD34(+) cells. Stroma cells so modified expressed reduced levels of intercellular adhesion molecule-1 (ICAM1; CD54); blockade of ICAM1 in unmodified stroma was associated with reduced apoptosis in cocultured CD34(+) MDS marrow cells. These data suggest role for dysregulation of TWIST in the pathophysiology of MDS. Conceivably, TWIST or components in the signaling pathway could serve as therapeutic targets for patients with MDS.

Apheresis as Therapy for Patients with Severe Sepsis and Multiorgan Dysfunction Syndrome

Progressive multiorgan dysfunction syndrome may occur in the course of sepsis and septic shock as well as after various intoxications, pancreatitis, crush injuries, and major surgery. Despite conventional intensive care therapies, the prognosis in these patients is still poor. Apheresis, which uses more selective adsorption techniques, can lower the extent of toxins and cytokines in blood. This is achieved in clinical practice by, e.g., using polymyxin B as adsorbent. Although significantly lowered, the mortality is still about 50% with this technique. By unselective plasma exchange, the mortality is reduced down to 20 to 40%. A controlled and randomized study has shown a significant benefit. The centrifugation technique may be favorable over plasma filtration. Not only removal but also replacement with plasma seems important. In the future, probably selective techniques will be used in the early stages of sepsis while unselective plasma exchange may be useful in a disseminated situation.