Dynamic changes of pathophysiological characteristics during liver regeneration induced by associating liver partition and portal vein ligation for staged hepatectomy (ALPPS).

Background: Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) has been considered as a novel surgical method to treat patients with unresectable liver cancer. Whereas, the process of liver regeneration during ALPPS is still unclear. To comprehensively analyze the changes in transcriptional profiles, histological features, and local immune cell infiltration within the future liver remnant (FLR) during liver regeneration in patients who have undergone ALPPS. Methods: Bulk RNA sequencing (RNA-seq) data of FLR from 10 patients undergoing ALPPS (cohort 1) were analyzed to compare the transcriptional profile changes of FLR dynamically. FLR tissues obtained from 58 ALPPS patients (cohort 2) were collected for immunohistochemistry (IHC) staining of immune cell clusters, and proliferation markers were performed. Three types of rat ALPPS models, including ALPPS (30% FLR), Zurich ALPPS, and ALPPS (10% FLR), were constructed for sampling at dynamic points (0, 1, 2, 4, and 7 days), and bulk RNA-seq was conducted and analyzed based on FLR from ALPPS (10% FLR). Dynamic observation of FLR growth kinetics, immunofluorescence (IF) and IHC staining analyses of proliferation markers, and immune cell infiltrations were performed based on rat models. Results: Bulk RNA-seq data of FLR from ALPPS patients revealed significant enrichment of pathways related to liver regeneration, including hypoxia, angiogenesis, leukocyte migration, and apoptosis in stage 2 compared to stage 1. After an interval of 7 to 28 days (average 15.0 days) during ALPPS, the FLR volume of 58 patients and proliferation markers increased significantly. The total relative hepatocyte number increased by 47.1% (P<0.001) from stage 1 to stage 2. Three different rat ALPPS models exhibited obvious growth of FLR and dynamic transcriptional patterns based on ALPPS (10% FLR) models. Pattern 1, associated with the initiation phase [postoperative day (POD) 1], featured peaks in genes related to DNA replication, RNA translation, and protein biosynthesis. Pattern 2, corresponding to the proliferation phase (POD 2), showed enrichment in pathways related to cell proliferation and liver regeneration. Pattern 3, linked to the renewal phase (POD 4), had increased expression of genes involved in autophagy, protein degradation, and energy supply. Pattern 4, characterizing the terminal phase (POD 7), was marked by elevated expression of chemotaxis, immune response pathways, and natural killer (NK) cells cytotoxicity. Neutrophils and macrophages were observed to infiltrate in FLR of rat ALPPS models as early as POD 1. Furthermore, pathways related to apoptosis and cell death and increased expression of apoptosis marker cleaved caspase 3 by IHC staining, was observed in stage 2 compared to stage 1 of FLR from ALPPS patients, and transiently elevated liver enzymes indicating hepatocyte damage were observed in POD 1 after stage 1 and gradually dropped and recovered by POD 7. Conclusions: This study provides a comprehensive transcriptional, histological, and immune environment landscape, offering valuable insights into liver regeneration induced by ALPPS.