53 - Freie Mitteilung
Inflammation & transplantation
16. Mai 2019, 10:15 - 11:45, Szenario 1, 5. OG
Hypoxia sensing of hepatic stellate cells leads to VEGF-dependent angiogenesis to accelerate liver regeneration in ALPPS
K. Dirscherl1, B. Beck Schimmer1, M. Schläpfer1, R. Wenger1, D. Spahn1, Presenter: E. Schadde1, 2, 3 (1Zürich, 2Winterthur, 3Chicago/USA)
Rerouting portal vein flow induces slow liver regeneration. Associating Liver Partition and portal vein ligation for staged hepatectomy(ALPPS) induces rapid regeneration by adding parenchymal transection to portal vein ligation(PVL). In ALPPS but not PVL, hypoxia inducible factor-1𝛼 (HIF-1𝛼) is upregulated in the liver and prolyl-hydroxylase inhibitors (PHI) also upregulate HIF-1𝛼 and accelerate liver regeneration. This study aims to clarify the role of HIF-1𝛼 in accelerating liver regeneration.
Rat models of PVL, ALPPS, PVL+PHI (Dimethyloxaloylglycin )and intraperitoneal injection of the PHI in normal livers without portal vein rerouting, were compared. Liver volume was evaluated by CT scan. Proliferation of hepatocytes (HC) was evaluated by Ki-67 and DAPI staining. Liver sinusoidal endothelial cell (LSEC) density was evaluated by von Willebrand Factor(vWF) staining and hepatic stellate cell (HSC) activation by desmin staining. In vitro, HEP3B-cells(HC), LX2-cells(HSCs) and TRP3-cells(LSECs) were cultured under hypoxic conditions and under treatment with PHI. Proliferation was measured over 72h with the iCELLigence cell culture system via impedance. Conditioned media experiments were performed using media from HCs, HSCs and LSECs exposed to PHI for 24h and transferred to the other cell lines. Concentration of vascular endothelial growth factor(VEGF) was measured in hypoxic HSCs and blocked. Transcriptome analysis was performed using RNA extracts from hypoxia/PHI treated HSCs and media conditioned LSECs.
PPVL induces slow liver regeneration, while ALPPS and PVL treated with PHI accelerates volume increase and KI-67 proliferation by a factor of 1.8 and 3 respectively. While PHI without portal rerouting has no impact on volume, it leads to increased vascular density by vWF staining, also observed in ALPPS and PVL+DMOG. HSC activation is present in all rapid regeneration models and also the PHI treated normal livers without proliferation. In culture, PHI has an anti-proliferative effect on HCs, HSC and LSEC. However, transfer of media of PHI-treated HSC induces VEGF dependent proliferation of LSEC. Transcriptome analysis shows dominant expression of angiogenesis and matrix remodeling pathways.
In conclusion, hypoxia signaling by HSCs induces VEGF-dependent angiogenesis and leads to rapid liver regeneration in ALPPS.