Surgical resection remains the gold standard for liver tumor treatment, yet the emergence of post-operative liver failure, known as the small for size syndrome (SFSS), poses a significant challenge. The activation of hypoxia sensors in a SFSS liver remnant initiated early angiogenesis, improving vascular architecture, safeguarding against liver failure and reducing mortality. The study aimed to elucidate vascular remodeling mechanisms in SFSS, its impact on hepatocyte function and subsequent liver failure. Mice underwent extended partial hepatectomy to induce SFSS, with a subset exposed to hypoxia immediately after surgery. Hypoxia bolstered post-hepatectomy survival rates. Early proliferation of liver sinusoidal cells, coupled with recruitment of putative endothelial progenitor cells (EPC), increased vascular density, improved lobular perfusion, and limited hemorrhagic events in the regenerating liver under hypoxia. Administration of granulocyte colony stimulating factor (G-CSF) in hepatectomized mice mimicked the effects of hypoxia on vascular remodeling and EPC recruitment, but failed to rescue survival. Compared to normoxia, hypoxia favored hepatocyte function over proliferation, promoting functional preservation in the regenerating remnant. Injection of AAV8-TBG-HNF4α virus for hepatocyte-specific overexpression of HNF4α, the master regulator of hepatocyte function, enforced functionality in proliferating hepatocytes but did not rescue survival. The combination of HNF4α overexpression and G-CSF treatment rescued survival after SFSS-setting hepatectomy. In summary, SFSS arises from an imbalance and desynchronized interplay between functional regeneration and vascular restructuring. To improve survival following SFSS-hepatectomy, it is essential to adopt a two-pronged strategy aimed at preserving the function of proliferating parenchymal cells and simultaneously attenuating vascular damage.
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