Background
Hepatic ischaemia-reperfusion injury (HIRI) is inevitable in complicated liver surgery and is a major factor leading to postoperative complications and liver dysfunction. Studies have shown that the paracrine mechanisms of stem cell may be essential to tissue repair and functional improvement after transplantation. However, the role of the adipose-derived mesenchymal stem cell secretome (ASC-secretome) in liver regeneration in large animals remains to be determined.
Methods
Twenty-four miniature pigs were subjected to laparoscopic liver ischaemia-reperfusion combined with partial hepatectomy and divided into the following four groups: the saline group, the DMEM group, the ASC group and the ASC-secretome group. Serum and liver tissue samples were collected before the operation and at 1, 3 and 7 days after the operation, and changes in tissue pathology, serum inflammation, liver function, angiogenesis-related factors and liver tissue regeneration-related genes and proteins were evaluated.
Results
Detailed histological analysis showed that ASCs and the ASC-secretome changed pathological damage to liver tissue after liver ischaemia-reperfusion combined with partial hepatectomy (1 and 3 days: p < 0.01). Compared with the saline and DMEM control groups, the ASC-secretome group had significantly reduced expression levels of ALP (1 and 3 days: p < 0.05), ALT (1 day: p < 0.01; 3 days: p < 0.05) and AST (1 and 3 days: p < 0.01), which promoted the recovery of liver function. Moreover, detection of the expression levels of TNF-α and IL-1β (1 day: p < 0.01; 3 days: p < 0.05), IL-6 (1 and 3 days: p < 0.05) and IL-10 (1 and 3 days: p < 0.01) in serum confirmed that the ASC-secretome had obvious anti-inflammatory effects. In addition, the ASC-secretome increased the expression levels of ANG-1 (3 days: p < 0.01), ANG-2 (3 and 7 days: p < 0.01) and VEGF (1 and 7 days: p < 0.05; 3 days: p < 0.01) and promoted angiogenesis during liver regeneration. Moreover, it promoted the mRNA expression of HGF and Cyclin D1 (1 and 3 days: p < 0.01); increased the levels of p-STAT3 (1 and 3 days: p < 0.01), PCNA and Ki67 (1 and 3 days: p < 0.01; 7 days: p < 0.05); inhibited the negative feedback of SOCS3 (1 and 3 days: p < 0.01); and decreased the mRNA expression of TGF-β (3 days: p < 0.01). The cytokines and growth factors detected in the ASC-secretome included TNF-α, IL-6, IL-1β, ANG-1, ANG-2, VEGF and b-FGF.
Conclusion
The ASC-secretome alleviates the inflammatory response induced by ischaemia-reperfusion combined with partial hepatectomy in miniature pigs and promotes liver regeneration.
Hepatic ischaemia reperfusion injury (HIRI) is a major factor leading to liver dysfunction after liver resection and liver transplantation. Adipose‐derived mesenchymal stem cells (ADSCs) have potential therapeutic effects on HIRI. Exosomes derived from ADSCs (ADSCs‐exo) have been widely studied as an alternative of ADSCs therapy. Thus, the aim of this study was to evaluate the potential protective effect and related mechanism of ADSCs‐exo on HIRI subsequent to hepatectomy. Rats were randomly divided into four groups: Sham, I30R+PH, ADSCs and ADSCs‐exo group. After 24 h of reperfusion, liver and serum of the rats were immediately collected. ADSCs‐exo improved liver function, inhibited oxidative stress and reduced apoptosis of hepatocytes in HIRI subsequent to hepatectomy in rats. ADSCs‐exo significantly promoted the recovery of mitochondrial function, markedly increased the content of ATP in the liver tissue, and improved the ultrastructure of mitochondria in hepatocytes. Moreover, ADSCs‐exo significantly increased the expression of OPA‐1, MFN‐1 and MFN‐2 proteins related to mitochondrial fusion, while DRP‐1 and Fis‐1 mRNA and protein expression associated with mitochondrial fission were significantly decreased after the treatment with ADSCs‐exo. In addition, ADSCs‐exo significantly increased the expression of PGC‐1α, NRF‐1 and TFAM genes and proteins related to mitochondrial biogenesis. ADSCs‐exo improves liver function induced by HIRI subsequent to hepatectomy in rats and maintains mitochondrial homeostasis by inhibiting mitochondrial fission, promoting mitochondrial fusion and promoting mitochondrial biogenesis. Therefore, ADSCs‐exo may be considered as a potential promising alternative to ADSCs in the treatment of HIRI subsequent to hepatectomy.
Although accumulating evidence indicates that exosomes have a positive therapeutic effect on hepatic ischemia–reperfusion injury (HIRI), studies focusing on the alleviation of liver injury by exosomes derived from adipose-derived mesenchymal stem cells (ADSCs-Exo) based on the inhibition of cell pyroptosis have not yet been reported. Exosomes contain different kinds of biologically active substances such as proteins, lipids, mRNAs, miRNAs, and signaling molecules. These molecules are widely involved in cell–cell communication, cell signal transmission, proliferation, migration, and apoptosis. Therefore, we investigated the positive effects exerted by ADSCs-Exo after hepatic ischemia–reperfusion with partial resection injury in rats. In this study, we found that the post-operative tail vein injection of ADSCs-Exo could effectively inhibit the expression of pyroptosis-related factors such as NLRP3, ASC, caspase-1, and GSDMD-N, and promote the expression of regeneration-related factors such as Cyclin D1 and VEGF. Moreover, we found that the above cellular activities were associated with the NF-κB and Wnt/β-catenin signaling pathways. According to the results, ADSCs and ADSCs-Exo can reduce pyroptosis in the injured liver and promote the expression of those factors related to liver regeneration, while they can inhibit the NF-κB pathway and activate the Wnt/β-catenin pathway. However, although adipose-derived mesenchymal stem cell (ADSC) transplantation can reduce liver injury, it leads to a significant increase in the pyroptosis-related protein GSDMD-N expression. In conclusion, our study shows that ADSCs-Exo has unique advantages and significance as a cell-free therapy to replace stem cells and still has a broad research prospect in the clinical diagnosis and treatment of liver injuries.
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