Cell-Based Regeneration and Treatment of Liver Diseases

Codonopsis pilosula polysaccharides (CPP) intervention alleviates sterigmatocystin (STC)-induced liver injury and gut microbiota dysbiosis

Codonopsis pilosula polysaccharides (CPP), the main active ingredient of Codonopsis pilosula, has gained significant attention as a liver-protective agent. Previous studies have demonstrated that CPP could alleviate gut microbiota dysbiosis in colitis or obese mice. However, the effects of CPP on mycotoxin-induced liver injury and gut microbiota dysbiosis are still poorly understood. In this study, we aimed to investigate the protective effects of CPP on sterigmatocystin (STC)-induced liver injury, as well as its regulatory effects on gut microbiota. Our results revealed that CPP intervention significantly alleviated STC-induced liver injury, as evidenced by decreased liver index, reduced liver histopathological changes, and modulation of related molecular markers. Additionally, we found that CPP could alleviate liver injury by reducing liver inflammation and oxidative stress, inhibiting hepatocyte apoptosis, and regulating lipid metabolism. Notably, we also observed that CPP could alleviate STC-induced gut microbiota dysbiosis by modulating the diversity and richness of gut microbiota, suggesting that gut microbiota modulation may also serve as a mechanism for CPP-mediated remission of liver injury. In summary, our study not only provided a new theoretical basis for understanding the hepatotoxicity of STC and the protective effects of CPP against STC-induced liver injury, but also provided new perspectives for the application of CPP in the fields of food, healthcare products, and medicine.

Proteomics reveals the pharmacological mechanism of flavonoids from Astragali Complanati Semen in preventing chronic liver injury

BACKGROUND

Total flavonoids from Astragali Complanati Semen (TFACS), the main active ingredients in Astragali Complanati Semen (ACS), have been shown to have a protective effect on chronic liver injury (CLI), but the hepatoprotective targets and signalling pathways involved are unclear.

PURPOSE

The aim of our study was to identify the anti-CLI targets and signalling pathways of TFACS and to comprehensively elucidate its mechanism of action via proteomics analysis combined with in vivo and in vitro experiments.

METHODS

A CLI mouse model was generated via intraperitoneal injection of carbon tetrachloride (CCl4) (CCl4: olive oil = 1:4, 2 ml/kg, twice a week for 6 weeks). The hepatoprotective effect of TFACS was assessed by observing the pathological structure of the liver and analysing indicators of liver function. The key pathways and targets related to the hepatoprotective effect of TFACS were identified via 4D-label-free quantitative proteomics technology and further verified via in vivo indicator validation and in vitro cell experiments.

RESULTS

TFACS administration significantly normalized the histopathological structure and function of the liver, decreased the levels of inflammatory factors and oxidative stress indicators, and reduced the iron staining area and the levels of hepcidin and iron in the liver compared with those in the CLI model. A total of 424 differentially expressed proteins (DEPs) were identified between the TFACS and model groups, and these DEPs were enriched in the focal adhesion, PI3K-Akt, and ferroptosis pathways. Akt1, Pik3ca, NF-κB p65, Itga5, Itgb5, Itga6, Prkca, Fn1, Tfrc, and Vdac3 were identified as key targets of TFACS. TFACS administration significantly reversed the changes in the gene and protein expression of the key targets compared with those in the model group. In addition, TFACS treatment significantly reduced the levels of inflammatory cytokines and inhibited Akt1, NF-κB p65 and FAK activation in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages. In an erastin-induced l-O2 ferroptosis cell model, treatment with TFACS normalized the mitochondrial structure, reduced the protein levels of Tfrc and Vdac3, inhibited lipid peroxidation, and reduced the amount of Fe2+ in the mitochondria.

CONCLUSION

TFACS protected against CLI, and its mechanism of action may be related to inhibition of the focal adhesion, PI3K/Akt and ferroptosis signalling pathways.

Immune regulation and therapeutic application of T regulatory cells in liver diseases

CD4+ CD25+ FOXP3+ T regulatory cells (Tregs) are a subset of the immunomodulatory cell population that can inhibit both innate and adaptive immunity by various regulatory mechanisms. In hepatic microenvironment, proliferation, plasticity, migration, and function of Tregs are interrelated to the remaining immune cells and their secreted cytokines and chemokines. In normal conditions, Tregs protect the liver from inflammatory and auto-immune responses, while disruption of this crosstalk between Tregs and other immune cells may result in the progression of chronic liver diseases and the development of hepatic malignancy. In this review, we analyze the deviance of this protective nature of Tregs in response to chronic inflammation and its involvement in inducing liver fibrosis, cirrhosis, and hepatocellular carcinoma. We will also provide a detailed emphasis on the relevance of Tregs as an effective immunotherapeutic option for autoimmune diseases, liver transplantation, and chronic liver diseases including liver cancer.

Orchestrated regulation of immune inflammation with cell therapy in pediatric acute liver injury

Acute liver injury (ALI) in children, which commonly leads to acute liver failure (ALF) with the need for liver transplantation, is a devastating life-threatening condition. As the orchestrated regulation of immune hemostasis in the liver is essential for resolving excess inflammation and promoting liver repair in a timely manner, in this study we focused on the immune inflammation and regulation with the functional involvement of both innate and adaptive immune cells in acute liver injury progression. In the context of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) pandemic, it was also important to incorporate insights from the immunological perspective for the hepatic involvement with SARS-CoV-2 infection, as well as the acute severe hepatitis of unknown origin in children since it was first reported in March 2022. Furthermore, molecular crosstalk between immune cells concerning the roles of damage-associated molecular patterns (DAMPs) in triggering immune responses through different signaling pathways plays an essential role in the process of liver injury. In addition, we also focused on DAMPs such as high mobility group box 1 (HMGB1) and cold-inducible RNA-binding protein (CIRP), as well as on macrophage mitochondrial DNA-cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway in liver injury. Our review also highlighted novel therapeutic approaches targeting molecular and cellular crosstalk and cell-based therapy, providing a future outlook for the treatment of acute liver injury.

Magnetic Nanostructures and Stem Cells for Regenerative Medicine, Application in Liver Diseases

The term "liver disease" refers to any hepatic condition that leads to tissue damage or altered hepatic function and can be induced by virus infections, autoimmunity, inherited genetic mutations, high consumption of alcohol or drugs, fat accumulation, and cancer. Some types of liver diseases are becoming more frequent worldwide. This can be related to increasing rates of obesity in developed countries, diet changes, higher alcohol intake, and even the coronavirus disease 2019 (COVID-19) pandemic was associated with increased liver disease-related deaths. Although the liver can regenerate, in cases of chronic damage or extensive fibrosis, the recovery of tissue mass is impossible, and a liver transplant is indicated. Because of reduced organ availability, it is necessary to search for alternative bioengineered solutions aiming for a cure or increased life expectancy while a transplant is not possible. Therefore, several groups were studying the possibility of stem cells transplantation as a therapeutic alternative since it is a promising strategy in regenerative medicine for treating various diseases. At the same time, nanotechnological advances can contribute to specifically targeting transplanted cells to injured sites using magnetic nanoparticles. In this review, we summarize multiple magnetic nanostructure-based strategies that are promising for treating liver diseases.

Multiple Shades of Gray-Macrophages in Acute Allograft Rejection

Long-term results following solid organ transplantation do not mirror the excellent short-term results achieved in recent decades. It is therefore clear that current immunosuppressive maintenance protocols primarily addressing the adaptive immune system no longer meet the required clinical need. Identification of novel targets addressing this shortcoming is urgently needed. There is a growing interest in better understanding the role of the innate immune system in this context. In this review, we focus on macrophages, which are known to prominently infiltrate allografts and, during allograft rejection, to be involved in the surge of the adaptive immune response by expression of pro-inflammatory cytokines and direct cytotoxicity. However, this active participation is janus-faced and unspecific targeting of macrophages may not consider the different subtypes involved. Under this premise, we give an overview on macrophages, including their origins, plasticity, and important markers. We then briefly describe their role in acute allograft rejection, which ranges from sustaining injury to promoting tolerance, as well as the impact of maintenance immunosuppressants on macrophages. Finally, we discuss the observed immunosuppressive role of the vitamin-like compound tetrahydrobiopterin and the recent findings that suggest the innate immune system, particularly macrophages, as its target.

Cellular therapies in liver and pancreatic diseases

Over the past two decades, developments in regenerative medicine in gastroenterology have been greatly enhanced by the application of stem cells, which can self-replicate and differentiate into any somatic cell. The discovery of induced pluripotent stem cells has opened remarkable perspectives on tissue regeneration, including their use as a bridge to transplantation or as supportive therapy in patients with organ failure. The improvements in DNA manipulation and gene editing strategies have also allowed to clarify the physiopathology and to correct the phenotype of several monogenic diseases, both in vivo and in vitro. Further progress has been made with the development of three-dimensional cultures, known as organoids, which have demonstrated morphological and functional complexity comparable to that of a miniature organ. Hence, owing to its protean applications and potential benefits, cell and organoid transplantation has become a hot topic for the management of gastrointestinal diseases. In this review, we describe current knowledge on cell therapies in hepatology and pancreatology, providing insight into their future applications in regenerative medicine.

Novel, Innovative Models to Study Ischemia/Reperfusion-Related Redox Damage in Organ Transplantation

The implementation of ex vivo organ machine perfusion (MP) into clinical routine undoubtedly helped to increase the donor pool. It enables not just organ assessment, but potentially regeneration and treatment of marginal organs in the future. During organ procurement, redox-stress triggered ischemia-reperfusion injury (IRI) is inevitable, which in addition to pre-existing damage negatively affects such organs. Ex vivo MP enables to study IRI-associated tissue damage and its underlying mechanisms in a near to physiological setting. However, research using whole organs is limited and associated with high costs. Here, in vitro models well suited for early stage research or for studying particular disease mechanisms come into play. While cell lines convince with simplicity, they do not exert all organ-specific functions. Tissue slice cultures retain the three-dimensional anatomical architecture and cells remain within their naïve tissue-matrix configuration. Organoids may provide an even closer modelling of physiologic organ function and spatial orientation. In this review, we discuss the role of oxidative stress during ex vivo MP and the suitability of currently available in vitro models to further study the underlying mechanisms and to pretest potential treatment strategies.

Liver Regeneration by Hematopoietic Stem Cells: Have We Reached the End of the Road?

The liver is the organ with the highest regenerative capacity in the human body. However, various insults, including viral infections, alcohol or drug abuse, and metabolic overload, may cause chronic inflammation and fibrosis, leading to irreversible liver dysfunction. Despite advances in surgery and pharmacological treatments, liver diseases remain a leading cause of death worldwide. To address the shortage of donor liver organs for orthotopic liver transplantation, cell therapy in liver disease has emerged as a promising regenerative treatment. Sources include primary hepatocytes or functional hepatocytes generated from the reprogramming of induced pluripotent stem cells (iPSC). Different types of stem cells have also been employed for transplantation to trigger regeneration, including hematopoietic stem cells (HSCs), mesenchymal stromal cells (MSCs), endothelial progenitor cells (EPCs) as well as adult and fetal liver progenitor cells. HSCs, usually defined by the expression of CD34 and CD133, and MSCs, defined by the expression of CD105, CD73, and CD90, are attractive sources due to their autologous nature, ease of isolation and cryopreservation. The present review focuses on the use of bone marrow HSCs for liver regeneration, presenting evidence for an ongoing crosstalk between the hematopoietic and the hepatic system. This relationship commences during embryogenesis when the fetal liver emerges as the crossroads between the two systems converging the presence of different origins of cells (mesoderm and endoderm) in the same organ. Ample evidence indicates that the fetal liver supports the maturation and expansion of HSCs during development but also later on in life. Moreover, the fact that the adult liver remains one of the few sites for extramedullary hematopoiesis—albeit pathological—suggests that this relationship between the two systems is ongoing. Can, however, the hematopoietic system offer similar support to the liver? The majority of clinical studies using hematopoietic cell transplantation in patients with liver disease report favourable observations. The underlying mechanism—whether paracrine, fusion or transdifferentiation or a combination of the three—remains to be confirmed.

Mesenchymal stem cell homing to improve therapeutic efficacy in liver disease

Mesenchymal stem cell (MSC) transplantation, as an alternative strategy to orthotopic liver transplantation, has been evaluated for treating end-stage liver disease. Although the therapeutic mechanism of MSC transplantation remains unclear, accumulating evidence has demonstrated that MSCs can regenerate tissues and self-renew to repair the liver through differentiation into hepatocyte-like cells, immune regulation, and anti-fibrotic mechanisms. Multiple clinical trials have confirmed that MSC transplantation restores liver function and alleviates liver damage. A sufficient number of MSCs must be home to the target tissues after administration for successful application. However, inefficient homing of MSCs after systemic administration is a major limitation in MSC therapy. Here, we review the mechanisms and clinical application status of MSCs in the treatment of liver disease and comprehensively summarize the molecular mechanisms of MSC homing, and various strategies for promoting MSC homing to improve the treatment of liver disease.