Kleine Hepatozyten (SH) für eine zellbasierte Leberersatztherapie Small Hepatocytes (SH) for an alternative liver therapy

Due to the shortage of donor organs, advanced liver cirrhosis is associated with ah igh mortality rate. A cell based therapy may present as a true alternative to stabilise the patient in the middle and long term, thereby decreasing the mortality rate on the transplant waiting list. However, limitation of cellbased therapies consists of the availability of functional human hepatocytes whereas hepatic progenitor cells such as small hepatocytes (SH) are ap ossible cell source, because they have proliferation capacity [1]. For ab etter characterisation of these cells, we used explanted cirrhotic livers, as well as surgical liver specimens. SH cells were separated by a percoll density gradient centrifugation. To further characterise these cells we cultured them in FCS free medium [2] and used fluorescence staining and PCR analysis. The isolation of SH cells from resected liver specimens showed an inverse correlation between donor age and the number of isolated SH cells. However, the highest number of SH cells was consistently isolated from explanted cirrhotic livers compared to resected liver specimens. SH cells express liver specific markers such as transferrin, cytokeratin 18 and albumin while the stem cell marker CD 90 was undetectable. Moreover, vimentin was not present as well as specific degrading enzymes such as cytochrome P450 1A2 and 3A4. However, during this differentiation stage SH cells feature only limited cytochrome P450 gene expression and activity, suggesting that SH cells are not fully differentiated into adult hepatocytes. The absence of vimentin supports that these cells are originally of endodermal origin. Further characterisation of SH cells is needed to determine its role in the liver and its possible use in future applications. Einleitung Das Vorliegen einer fortgeschrittenen Leberzirrhose ist aufgrund des aktuellen Spendermangels mit einer hohen Mortalitat assoziiert. Eine zellbasierte Therapie konnte Patienten helfen ihre Leberfunktion zu stabilisieren und die damit verbundene Mortalitat zu reduzieren. Da jedoch die Verfugbarkeit von funktionellen humanen Hepatozyten limitiert ist, versuchen Wissenschaftlerteams in der ganzen Welt neue Alternativen zu finden. Unter vielen moglichen erscheinen hepatische Vorlauferzellen wie kleine Hepatozyten (SH) eine mogliche Zellquelle dar zu stellen, da sie nach Isolation in-vitro proliferieren konnen [1]. Methodik Zur besseren Charakterisierung dieser Zellen wurden SH-Zellen aus explantierten, zirrhotischen Lebern sowie aus chirurgischen Leberresektaten uber eine Dichtegradienten-Zentrifugation mit Percoll separiert. Die Zellvereinzelung erfolgte uber den Verdau mit Collagenase. Fur die nachfolgende Charakterisierung erfolgte die Kultivierung der Zellen in FCS freiem Medium [2] mit anschliesender