Mechanisms Underlying Cell Therapy in Liver Fibrosis: An Overview

Liver sinusoidal endothelial cell: An important yet often overlooked player in the liver fibrosis

Liver sinusoidal endothelial cells (LSECs) are liver-specific endothelial cells with the highest permeability than other mammalian endothelial cells, characterized by the presence of fenestrae on their surface, the absence of diaphragms and the lack of basement membrane. Located at the interface between blood and other liver cell types, LSECs mediate the exchange of substances between the blood and the Disse space, playing a crucial role in maintaining substance circulation and homeostasis of multicellular communication. As the initial responders to chronic liver injury, the abnormal LSEC activation not only changes their own physicochemical properties but also interrupts their communication with hepatic stellate cells and hepatocytes, which collectively aggravates the process of liver fibrosis. In this review, we have comprehensively updated the various pathways by which LSECs were involved in the initiation and aggravation of liver fibrosis, including but not limited to cellular phenotypic change, the induction of capillarization, decreased permeability and regulation of intercellular communications. Additionally, the intervention effects and latest regulatory mechanisms of anti-fibrotic drugs involved in each aspect have been summarized and discussed systematically. As we studied deeper into unraveling the intricate role of LSECs in the pathophysiology of liver fibrosis, we unveil a promising horizon that pave the way for enhanced patient outcomes.

Liver Fibrosis Amelioration by Macrophage-Biomimetic Polydopamine Nanoparticles via Synergistically Alleviating Inflammation and Scavenging ROS

The progression of liver fibrosis is determined by the interaction of damaged hepatocytes, active hepatic stellate cells, and macrophages, contributing to the development of oxidative stress and inflammatory environments within the liver. Unfortunately, the current pharmacological treatment for liver fibrosis is limited by its inability to regulate inflammation and oxidative stress concurrently. In this study, we developed a cell membrane biomaterial for the treatment of liver fibrosis, which we designated as PM. PM is a biomimetic nanomaterial constructed by encapsulating polydopamine (PDA) with a macrophage membrane (MM). It is hypothesized that PM nanoparticles (NPs) can successfully target the site of inflammation, simultaneously inhibit inflammation, and scavenge reactive oxygen species (ROS). In vitro experiments demonstrated that PM NPs exhibited strong antioxidant properties and the ability to neutralize pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β). Moreover, the capacity of PM NPs to safeguard cells from oxidative stress and their anti-inflammatory efficacy in an inflammatory model were validated in subsequent cellular experiments. Additionally, PM NPs exhibited a high biocompatibility. In a mouse model of hepatic fibrosis, PM NPs were observed to aggregate efficiently in the fibrotic liver, displaying excellent antioxidant and anti-inflammatory properties. Notably, PM NPs exhibited superior targeting, anti-inflammatory, and ROS scavenging abilities in inflamed tissues compared to MM, PDA, or erythrocyte membrane-encapsulated PDA. Under the synergistic effect of anti-inflammation and antioxidant, PM NPs produced significant therapeutic effects on liver fibrosis in mice. In conclusion, the synergistic alleviation of inflammation and ROS scavenging by this specially designed nanomaterial, PM NPs, provides valuable insights for the treatment of liver fibrosis and other inflammatory- or oxidative stress-related diseases.

Hepatic inflammation and fibrosis are profiles related to mid-term mortality in biopsy-proven MASLD: A multicenter study in Japan

AIMS

A multi-stakeholder consensus has proposed MASLD (metabolic dysfunction-associated steatotic liver disease). We aimed to investigate the pathological findings related to the mid-term mortality of patients with biopsy-proven MASLD in Japan.

METHODS

We enrolled 1349 patients with biopsy-proven MASLD. The observational period was 8010 person years. We evaluated independent factors associated with mortality in patients with MASLD by Cox regression analysis. We also investigated pathological profiles related to mortality in patients with MASLD using data-mining analysis.

RESULTS

The prevalence of MASH and stage 3/4 fibrosis was observed in 65.6% and 17.4%, respectively. Forty-five patients with MASLD died. Of these, liver-related events were the most common cause at 40% (n = 18), followed by extrahepatic malignancies at 26.7% (n = 12). Grade 2/3 lobular inflammation and stage 3/4 fibrosis had a 1.9-fold and 1.8-fold risk of mortality, respectively. In the decision-tree analysis, the profiles with the worst prognosis were characterised by Grade 2/3 hepatic inflammation, along with advanced ballooning (grade 1/2) and fibrosis (stage 3/4). This profile showed a mortality at 8.3%. Furthermore, the random forest analysis identified that hepatic fibrosis and inflammation were the first and second responsible factors for the mid-term prognosis of patients with MASLD.

CONCLUSIONS

In patients with biopsy-proven MASLD, the prevalence of MASH and advanced fibrosis was approximately 65% and 20%, respectively. The leading cause of mortality was liver-related events. Hepatic inflammation and fibrosis were significant factors influencing mid-term mortality. These findings highlight the importance of targeting inflammation and fibrosis in the management of patients with MASLD.

SIRT3: A potential therapeutic target for liver fibrosis

Sirtuin3 (SIRT3) is a nicotinamide adenine dinucleotide (NAD+)-dependent protein deacetylase located in the mitochondria, which mainly regulates the acetylation of mitochondrial proteins. In addition, SIRT3 is involved in critical biological processes, including oxidative stress, inflammation, DNA damage, and apoptosis, all of which are closely related to the progression of liver disease. Liver fibrosis characterized by the deposition of extracellular matrix is a result of long termed or repeated liver damage, frequently accompanied by damaged hepatocytes, the recruitment of inflammatory cells, and the activation of hepatic stellate cells. Based on the functions and pharmacology of SIRT3, we will review its roles in liver fibrosis from three aspects: First, the main functions and pharmacological effects of SIRT3 were investigated based on its structure. Second, the roles of SIRT3 in major cells in the liver were summarized to reveal its mechanism in developing liver fibrosis. Last, drugs that regulate SIRT3 to prevent and treat liver fibrosis were discussed. In conclusion, exploring the pharmacological effects of SIRT3, especially in the liver, may be a potential strategy for treating liver fibrosis.

Research Progress Regarding the Effect and Mechanism of Dietary Polyphenols in Liver Fibrosis

The development of liver fibrosis is a result of chronic liver injuries may progress to liver cirrhosis and liver cancer. In recent years, liver fibrosis has become a major global problem, and the incidence rate and mortality are increasing year by year. However, there are currently no approved treatments. Research on anti-liver-fibrosis drugs is a top priority. Dietary polyphenols, such as plant secondary metabolites, have remarkable abilities to reduce lipid metabolism, insulin resistance and inflammation, and are attracting more and more attention as potential drugs for the treatment of liver diseases. Gradually, dietary polyphenols are becoming the focus for providing an improvement in the treatment of liver fibrosis. The impact of dietary polyphenols on the composition of intestinal microbiota and the subsequent production of intestinal microbial metabolites has been observed to indirectly modulate signaling pathways in the liver, thereby exerting regulatory effects on liver disease. In conclusion, there is evidence that dietary polyphenols can be therapeutically useful in preventing and treating liver fibrosis, and we highlight new perspectives and key questions for future drug development.

Tyrosine kinase receptor B attenuates liver fibrosis by inhibiting TGF-β/SMAD signaling

BACKGROUND AND AIMS

Liver fibrosis is a leading indicator for increased mortality and long-term comorbidity in NASH. Activation of HSCs and excessive extracellular matrix production are the hallmarks of liver fibrogenesis. Tyrosine kinase receptor (TrkB) is a multifunctional receptor that participates in neurodegenerative disorders. However, paucity of literature is available about TrkB function in liver fibrosis. Herein, the regulatory network and therapeutic potential of TrkB were explored in the progression of hepatic fibrosis.

METHODS AND RESULTS

The protein level of TrkB was decreased in mouse models of CDAHFD feeding or carbon tetrachloride-induced hepatic fibrosis. TrkB suppressed TGF-β-stimulated proliferation and activation of HSCs in 3-dimensional liver spheroids and significantly repressed TGF-β/SMAD signaling pathway either in HSCs or in hepatocytes. The cytokine, TGF-β, boosted Nedd4 family interacting protein-1 (Ndfip1) expression, promoting the ubiquitination and degradation of TrkB through E3 ligase Nedd4-2. Moreover, carbon tetrachloride intoxication-induced hepatic fibrosis in mouse models was reduced by adeno-associated virus vector serotype 6 (AAV6)-mediated TrkB overexpression in HSCs. In addition, in murine models of CDAHFD feeding and Gubra-Amylin NASH (GAN), fibrogenesis was reduced by adeno-associated virus vector serotype 8 (AAV8)-mediated TrkB overexpression in hepatocytes.

CONCLUSION

TGF-β stimulated TrkB degradation through E3 ligase Nedd4-2 in HSCs. TrkB overexpression inhibited the activation of TGF-β/SMAD signaling and alleviated the hepatic fibrosis both in vitro and in vivo . These findings demonstrate that TrkB could be a significant suppressor of hepatic fibrosis and confer a potential therapeutic target in hepatic fibrosis.

Immunomodulatory role of mesenchymal stem cell therapy in liver fibrosis

Liver fibrosis is a fibrogenic and inflammatory process that results from hepatocyte injury and is characterized by hepatic architectural distortion and resultant loss of liver function. There is no effective treatment for advanced fibrosis other than liver transplantation, but it is limited by expensive costs, immune rejection, and postoperative complications. With the development of regenerative medicine in recent years, mesenchymal stem cell (MSCs) transplantation has become the most promising treatment for liver fibrosis. The underlying mechanisms of MSC anti-fibrotic effects include hepatocyte differentiation, paracrine, and immunomodulation, with immunomodulation playing a central role. This review discusses the immune cells involved in liver fibrosis, the immunomodulatory properties of MSCs, and the immunomodulation mechanisms of MSC-based strategies to attenuate liver fibrosis. Meanwhile, we discuss the current challenges and future directions as well.

The effect of mesenchymal stem cells and imatinib on macrophage polarization in rat model of liver fibrosis

Liver fibrosis is a disorder in which inflammatory reactions play an important role, and central to the progression and pathogenesis of this disease are the immune-specific cells known as macrophages. Macrophage types are distinguished from each other by the expression of a series of surface markers. STAT6 and Arg1 play an important role in the polarization of macrophages, so these two factors are downstream of interleukin 4 (IL-4) and IL-13 cytokines and cause to differentiate M2. Therefore, this study aimed to compare the independent effects of imatinib and mesenchymal cell treatment on the polarization of macrophages in rat models of liver fibrosis. The liver fibrosis was induced by the injection of CCL4 for 6 weeks in Sprague-Dawley rats. Then, rats were divided into four different groups, and the effects of imatinib and mesenchymal cells on the expression of Arg1, Ly6c, and STAT6 were evaluated. Histopathology experiments considered the amelioration effect of treatments. Our results showed that Arg1 expression was significantly increased in the groups treated with mesenchymal cells and imatinib compared to the control group. On the other hand, expression of STAT6 was significantly increased in the imatinib-treated mice compared to mesenchymal and control groups. Moreover, the expression of LY6C significantly decreased in imatinib and mesenchymal treated groups compared to the control group. Therefore, our data showed that mesenchymal stem cells and imatinib significantly modulate the fibrotic process in rat models of fibrosis, probably by polarizing macrophages towards an anti-inflammatory profile and increasing the frequency of these cells in liver tissue.

Endoplasmic reticulum stress in innate immune cells - a significant contribution to non-alcoholic fatty liver disease

Liver disease and its complications affect millions of people worldwide. NAFLD (non-alcoholic fatty liver disease) is the liver disease associated with metabolic dysfunction and consists of four stages: steatosis with or without mild inflammation (NAFLD), non-alcoholic steatohepatitis (NASH), fibrosis, and cirrhosis. With increased necroinflammation and progression of liver fibrosis, NAFLD may progress to cirrhosis or even hepatocellular carcinoma. Although the underlying mechanisms have not been clearly elucidated in detail, what is clear is that complex immune responses are involved in the pathogenesis of NASH, activation of the innate immune system is critically involved in triggering and amplifying hepatic inflammation and fibrosis in NAFLD/NASH. Additionally, disruption of endoplasmic reticulum (ER) homeostasis in cells, also known as ER stress, triggers the unfolded protein response (UPR) which has been shown to be involved to inflammation and apoptosis. To further develop the prevention and treatment of NAFLD/NASH, it is imperative to clarify the relationship between NAFLD/NASH and innate immune cells and ER stress. As such, this review focuses on innate immune cells and their ER stress in the occurrence of NAFLD and the progression of cirrhosis.

Mesenchymal stromal cells: promising treatment for liver cirrhosis

Liver fibrosis is a wound-healing process that occurs in response to severe injuries and is hallmarked by the excessive accumulation of extracellular matrix or scar tissues within the liver. Liver fibrosis can be either acute or chronic and is induced by a variety of hepatotoxic causes, including lipid deposition, drugs, viruses, and autoimmune reactions. In advanced fibrosis, liver cirrhosis develops, a condition for which there is no successful therapy other than liver transplantation. Although liver transplantation is still a viable option, numerous limitations limit its application, including a lack of donor organs, immune rejection, and postoperative complications. As a result, there is an immediate need for a different kind of therapeutic approach. Recent research has shown that the administration of mesenchymal stromal cells (MSCs) is an attractive treatment modality for repairing liver injury and enhancing liver regeneration. This is accomplished through the cell migration into liver sites, immunoregulation, hepatogenic differentiation, as well as paracrine mechanisms. MSCs can also release a huge variety of molecules into the extracellular environment. These molecules, which include extracellular vesicles, lipids, free nucleic acids, and soluble proteins, exert crucial roles in repairing damaged tissue. In this review, we summarize the characteristics of MSCs, representative clinical study data, and the potential mechanisms of MSCs-based strategies for attenuating liver cirrhosis. Additionally, we examine the processes that are involved in the MSCs-dependent modulation of the immune milieu in liver cirrhosis. As a result, our findings lend credence to the concept of developing a cell therapy treatment for liver cirrhosis that is premised on MSCs. MSCs can be used as a candidate therapeutic agent to lengthen the survival duration of patients with liver cirrhosis or possibly reverse the condition in the near future.

Hesperetin derivative decreases CCl4 -induced hepatic fibrosis by Ptch1-dependent mechanisms

Hepatic fibrosis (HF), a continuous wound-healing response of the liver to repeated injuries, is characterized by abnormal extracellular matrix (ECM) accumulation. Hepatic stellate cells (HSCs) are considered a major cell type for ECM production. However, recent evidence indicates the lack of effective treatments for HF. Hesperetin, a Traditional Chinese Medicine monomer, has been isolated from the fruit peel of Citrusaurantium L. (Rutaceae). Growing evidence suggests the partial function of hesperetin in HF treatment. A hesperetin derivative (HD) was synthesized in our laboratory to increase the bioavailability and the water solubility of hesperetin. In this study, we detected the functions of HD in a mouse model of CCl₄ -induced HF and transforming growth factor-β1-stimulated HSC-T6 cells, in vivo and in vitro. HD reduced histological damage and CCl₄ -induced HF. Moreover, HD interference was associated with the activation of indicators in HSC-T6 cells, showing that HD is involved in HSCs activation in HF. Mechanistically, the Hedgehog pathway is involved in the HD treatment of HF, and HD may attenuate the aberrant expression of patched1. In conclusion, the studies indicate that HD may function as a potential antifibrotic Traditional Chinese Medicine monomer in HF therapy.

Kinsenoside attenuates liver fibro-inflammation by suppressing dendritic cells via the PI3K-AKT-FoxO1 pathway

Kinsenoside (KD) exhibits anti-inflammatory and immunosuppressive effects. Dendritic cells (DCs) are critical regulators of the pathologic inflammatory milieu in liver fibrosis (LF). Herein, we explored whether and how KD repressed development of LF via DC regulation and verified the pathway involved in the process. Given our analysis, both KD and adoptive transfer of KD-conditioned DCs conspicuously reduced hepatic histopathological damage, proinflammatory cytokine release and extracellular matrix deposition in CCl₄-induced LF mice. Of note, KD restrained the LF-driven rise in CD86, MHC-II, and CCR7 levels and, simultaneously, upregulated PD-L1 expression on DCs specifically, which blocked CD8⁺T cell activation. Additionally, KD reduced DC glycolysis, maintained DCs immature, accompanied by IL-12 decrease in DCs. Inhibiting DC function by KD disturbed the communication of DCs and HSCs with the expression or secretion of α-SMA and Col-I declined in the liver. Mechanistically, KD suppressed the phosphorylation of PI3K-AKT driven by LF or PI3K agonist, followed by enhanced nuclear transport of FoxO1 and upregulated interaction of FoxO1 with the PD-L1 promoter in DCs. PI3K inhibitor or si-IL-12 acting on DC could relieve LF, HSC activation and diminish the effect of KD. In conclusion, KD suppressed DC maturation with promoted PD-L1 expression via PI3K-AKT-FoxO1 and decreased IL-12 secretion, which blocked activation of CD8⁺T cells and HSCs, thereby alleviating liver injury and fibro-inflammation in LF.

Revealing the role of miRNA-489 as a new onco-suppressor factor in different cancers based on pre-clinical and clinical evidence

Recently, microRNAs (miRNAs) have shown to be potential therapeutic, diagnostic and prognostic targets in disease therapy. These endogenous non-coding RNAs contribute to regulation of different cellular events that are necessary for maintaining physiological condition. Dysregulation of miRNAs is correlated with development of various pathological events such as neurological disorders, cardiovascular diseases, and cancer. miRNA-489 is a new emerging miRNA and studies are extensively investigating its role in pathological conditions. Herein, potential function of miRNA-489 as tumor-suppressor in various cancers is described. miRNA-489 is able to sensitize cancer cells into chemotherapy by disrupting molecular pathways involved in cancer growth such as PI3K/Akt, and induction of apoptosis. The PROX1 and SUZ12 as oncogenic pathways, are affected by miRNA-489 in suppressing metastasis of cancer cells. Wnt/β-catenin as an oncogenic factor ensuring growth and malignancy of tumors is inhibited via miRNA-489 function. For enhancing drug sensitivity of tumors, restoring miRNA-489 expression is a promising strategy. The lncRNAs can modulate miRNA-489 expression in tumors and studies about circRNA role in miRNA-489 modulation should be performed. The expression level of miRNA-489 is a diagnostic tool for tumor detection. Besides, down-regulation of miRNA-489 in tumors provides unfavorable prognosis.

Cellular and Molecular Mechanisms Underlying Liver Fibrosis Regression

Chronic liver injury of different etiologies may result in hepatic fibrosis, a scar formation process consisting in altered deposition of extracellular matrix. Progression of fibrosis can lead to impaired liver architecture and function, resulting in cirrhosis and organ failure. Although fibrosis was previous thought to be an irreversible process, recent evidence convincingly demonstrated resolution of fibrosis in different organs when the cause of injury is removed. In the liver, due to its high regenerative ability, the extent of fibrosis regression and reversion to normal architecture is higher than in other tissues, even in advanced disease. The mechanisms of liver fibrosis resolution can be recapitulated in the following main points: removal of injurious factors causing chronic hepatic damage, elimination, or inactivation of myofibroblasts (through various cell fates, including apoptosis, senescence, and reprogramming), inactivation of inflammatory response and induction of anti-inflammatory/restorative pathways, and degradation of extracellular matrix. In this review, we will discuss the major cellular and molecular mechanisms underlying the regression of fibrosis/cirrhosis and the potential therapeutic approaches aimed at reversing the fibrogenic process.

Anti-inflammation treatment for protection of hepatocytes and amelioration of hepatic fibrosis in rats

Chronic inflammation is considered as an important pathophysiologic mechanism of hepatic cirrhosis, which induces hepatocyte injury and activates hepatic stellate cells (HSCs), thus resulting in hepatic fibrosis. Previous studies have reported that cyclooxygenase-2 (COX-2) inhibitor can effectively treat liver fibrosis, while somatostatin (SST) analogues inhibit the activation of HSCs. The present study aimed to investigate the effects of a COX-2 inhibitor, celecoxib, combined with a SST analogue, octreotide, for protection of hepatocytes and prevention of fibrosis in a rat model of hepatic fibrosis. Therefore, a hepatic fibrosis rat model was established following peritoneal injection of thioacetamide (TAA), and the rats were then treated with a combination of celecoxib and octreotide (TAA + C). Immunohistochemistry and western blotting assays were used to assess the expression levels of proteins associated with inflammation, epithelial-mesenchymal transition (EMT), proliferation, apoptosis and autophagy. H&E staining, transmission electron microscopy and scanning electron microscopy were used to evaluate the destruction of hepatocytes. Masson's Trichrome and Sirius Red were used to measure the degree of liver fibrosis. The results demonstrated that, compared with those of the control group, the degree of liver fibrosis and the expression of the intrahepatic inflammation factors were aggravated in the TAA group. Furthermore, the apoptosis rate, EMT and autophagy of hepatocytes were also increased in the TAA group. However, treatment with TAA + C restored the aforementioned increased levels compared with the TAA group. In conclusion, treatment of rats with the combination of celecoxib and octreotide could attenuate the progress of hepatic fibrosis via protection of hepatocytes by reducing apoptosis, EMT and autophagy in hepatocytes.

Circular RNA circUbe2k promotes hepatic fibrosis via sponging miR-149-5p/TGF-β2 axis

Abundant regulatory genes and complex circuits involving non-coding RNAs (ncRNAs) monitor the formation and development of hepatic fibrosis (HF). Circular RNAs (circRNAs) are a class of RNAs generated from protein coding genes by back-splicing, playing crucial roles in various pathological processes, including HF. However, little is known about mechanisms of action of circRNAs, let alone in HF. In this study, we found circUbe2k enhanced in CCl₄ -induced HF mice and LX-2 cells stimulated with TGF-β1, regulating the development of HF. Restraining the expression of circUbe2k inhibited α-SMA and Col1α1 expression in CCl₄ -induced HF mice and in LX-2 cells stimulated with TGF-β1. Furthermore, inhibiting circUbe2k expression reduced hepatic stellate cells (HSCs) activation and proliferation in vivo and in vitro. Mechanistically, we demonstrated a direct interaction between circUbe2k and miR-149-5p, which results in the modulation of TGF-β2 expressions. Together, circUbe2k may act as a "catalyst" of HSCs activation and HF through the circUbe2k/miR-149-5p/TGF-β2 axis. Our results provide unprecedented evidence for a significant role for circUbe2k to serve as a potential biomarker for HF therapy.

Effects of mesenchymal stem cells conditioned medium treatment in mice with cholestatic liver fibrosis

AIMS

The purpose of this work was to study the effects of mesenchymal stem cells conditioned medium (MSC CM) treatment in animals with cholestatic liver fibrosis.

MATERIALS AND METHODS

We induced cholestatic liver fibrosis by bile duct ligation in C57Bl/6 mice. In the 5th and 6th days after bile duct ligation proceeding, conditioned medium obtained of cultures of mesenchymal stem cells derived from adipose tissue was injected in the animals. Blood levels of hepatic transaminases, alkaline phosphatase and albumin were measured in each group. Analysis of collagen deposition was realized by Picro Sirius red staining and cytokine profiling was performed by cytometric bead array (CBA).

KEY FINDINGS

Our results showed that MSC CM treatment decreased levels of hepatic enzymes and collagen deposition in the liver. After MSC CM treatment, profibrotic IL-17A was decreased andIL-6 and IL-4 were increased.

SIGNIFICANCE

In summary, MSC CM treatment demonstrated therapeutic potential to cholestatic liver fibrosis, favoring matrix remodeling and cytokine profile towards liver regeneration.

Alpha lipoic acid priming enhances the hepatoprotective effect of adipose derived stem cells in CCl4 induced hepatic injury in-vitro

Mesenchymal stem cells are known to support hepatic defense against liver fibrosis. However, the fibrosis induced oxidative microenvironment affects the proliferative, regenerative, and angiogenic properties of mesenchymal stem cells. Alpha lipoic acid (ALA) is a strong anti-oxidant which has been shown to ameliorate the adverse effects of fibrosis that otherwise can lead to severe liver problems like cirrhosis and liver failure. Here, we studied the protective role of ALA primed adipose derived stem cells (ADSCs) against carbon tetrachloride (CCl₄₎ induced hepatotoxicity in primary hepatocytes in-vitro. Priming of ADSCs helped to abrogate the damaging effects of fibrosis induced oxidative stress as evidenced by significantly reduced levels of alkaline phosphatase (ALP), Alanine Aminotransferase (ALAT) along with decreased lactate dehydrogenase (LDH) release and improved superoxide dismutase (SOD) activity. ALA and ADSCs synergistically down-regulated the expression of Bax gene, an apoptosis regulator while enhancing cell proliferation by up-regulating the expression of Bcl2l1 gene. This treatment improved the expression of albumin (Alb), cytokeratin-8 (Ck8), and hepatic nuclear factor alpha (Hnf4α). Cytochrome P450 2E1 (Cyp2e1) and Alpha fetoprotein (Afp) were down-regulated to lessen the damage caused by CCl₄ treatment. Furthermore, paracrine release of several growth factors like hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF), interleukin-6 (IL-6), tumor necrosis factor alpha (TNFα), and insulin growth factor (IGF) reinforced the improved response of primary hepatocytes against CCl₄ induced hepatotoxicity in the presence of ALA primed ADSCs. This study suggests that ALA priming may improve the therapeutic potential of ADSCs against chronic liver problems by activating the nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream antioxidant factors heme oxygenase 1 (HO-1) and quinone acceptor oxidoreductase-1 (NQO1).

Hepatoprotective effect of bone marrow-derived mesenchymal stromal cells in CCl4-induced liver cirrhosis

Bone marrow mesenchymal stromal cells (BM-MSCs) are multipotent stem cells which are ideal candidates for use in regenerative medicine. The objectives of this study were to evaluate the hepatoprotective effect of BM-MSC and its combination treatment with silymarin in carbon tetrachloride (CCl₄)-induced liver cirrhosis animal model and to investigate whether tail vein or portal vein infusion was the ideal route for BM-MSC transplantation. 36 female Wistar rats were randomly divided into six groups (n = 6): Group 1 (normal control), Group 2 (received only CCl₄, disease model), Group 3 (CCl₄ + BM-MSCs through tail vein), Group 4 (CCl₄ + BM-MSCs through portal vein), Group 5 (CCl₄ + silymarin), Group 6 (CCl₄ + BM-MSCs + silymarin). On the 21st day after treatment, blood samples were collected for biochemical estimations. After the experiment, the rats were sacrificed. Liver was dissected out and processed for histopathology and scanning electron microscopy studies. Liver enzyme and marker analysis, histopathological studies indicated that the combination of BM-MSCs and silymarin was effective in treating liver cirrhosis. Transplanted BM-MSCs in combination with silymarin ameliorated the liver tissue damage through their immunoregulatory activities. Among the two routes, the intravenous administration of cells through the tail vein was found to be more effective and safe.

MicroRNA-489-3p Represses Hepatic Stellate Cells Activation by Negatively Regulating the JAG1/Notch3 Signaling Pathway

BACKGROUND

The transformation of hepatic stellate cells (HSCs) into collagen-producing myofibroblasts is a key event in hepatic fibrogenesis. Recent studies have shown that microRNAs (miRNAs) play a critical role in the transformation of HSCs. However, the function of miR-489-3p in liver fibrosis remains unclear.

METHODS

Here, we detected the levels of miR-489-3p and jagged canonical Notch ligand 1 (JAG1) in liver fibrosis by using CCl4-treated rats as an in vivo model and transforming growth factor-beta 1 (TGF-β1)-treated HSC cell lines LX-2 and HSC-T6 as in vitro models. The expression of profibrotic markers was affected by transfecting LX-2 cells with either miR-489-3p mimic or si-JAG1. A dual-luciferase reporter assay was carried out to study the interaction of JAG1 with miR-489-3p.

RESULTS

We found that miR-489-3p was remarkably decreased while JAG1 was increased in liver fibrosis models both in vivo and in vitro. Overexpression of miR-489-3p reduced the expression of profibrotic markers and the activation of LX-2 cells induced by TGF-β1. Moreover, miR-489-3p decreased the expression of jagged canonical Notch ligand 1 (JAG1) in LX-2 cells by interacting with its 3'-UTR. As JAG1 is a Notch ligand, decreased JAG1 by miR-489-3p inhibited the Notch signaling pathway. Moreover, the downregulation of JAG1 inhibited the expression of fibrotic markers.

CONCLUSION

Our results indicate that miR-489-3p can inhibit HSC activation by inhibiting the JAG1/Notch3 signaling pathway.

The development of mesenchymal stem cell therapy in the present, and the perspective of cell-free therapy in the future

Cirrhosis is a chronic condition that can lead to liver failure. Currently, the viable option for decreasing mortality is liver transplantation. However, transplant surgery is highly invasive. Therefore, cell-based therapy has been developed as an alternative. Based on promising findings from preclinical research, some new trials have been registered. One of them was autologous bone marrow cell infusion therapy and found that ameliorating liver fibrosis activated liver regeneration. Now, majority of trials focus on low-immunogenicity mesenchymal stem cells (MSCs) appropriate for allogeneic administration. However, despite about 20 years of research, only a limited number of cell-based therapies have entered routine practice. Furthermore, potential shortcomings of cell-based therapy include a limit on the number of cells, which may be administered, as well as their failure to infiltrate target organs. On the other hand, these research show that MSCs act as "conducting cells" and regulate host cells including macrophages via extracellular vesicles (EVs) or exosome signals, leading to ameliorate liver fibrosis and promote regeneration. Therefore, the concept of cell-free therapy, which makes use of cell-derived EVs or exosomes, is attracting attention. Cell-free therapies may be safely administered in large doses and are able to infiltrate target organs. However, development of cell-free therapy exhibits its own set of challenges and such therapy may not be completely curative in the context of liver disease. This review describes the history of cell-based therapy research and recent advances in cell-free therapy, as well as discussing the need for more effective therapies.

Therapeutic effect and safety of stem cell therapy for chronic liver disease: a systematic review and meta-analysis of randomized controlled trials

Background

Stem cell therapy is becoming an emerging therapeutic option for chronic liver disease (CLD). However, whether stem cell therapy is more effective than conventional treatment remains questionable. We performed a large-scale meta-analysis of randomized controlled trials (RCTs) to evaluate the therapeutic effects and safety of stem cell therapy for CLD.

Methods

We systematically searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL), and ClinicalTrials.gov databases for the period from inception through March 16, 2020. Primary outcomes were all-cause mortality and adverse events related to stem cell therapy. Secondary outcomes included the model for end-stage liver disease score, total bilirubin, albumin, alanine aminotransferase, prothrombin activity, and international normalized ratio. The standardized mean difference (SMD) and odds ratio (OR) with 95% confidence interval (CI) were calculated using a random-effects model.

Results

Twenty-four RCTs were included and the majority of these studies showed a high risk of bias. The meta-analysis indicated that compared with conventional treatment, stem cell therapy was associated with improved survival and liver function including the model of end-stage liver disease score, total bilirubin, and albumin levels. However, it had no obvious beneficial effects on alanine aminotransferase level, prothrombin activity, and international normalized ratio. Subgroup analyses showed stem cell therapy conferred a short-term survival benefit for patients with acute-on-chronic liver failure (ACLF), a single injection was more effective than multiple injections, hepatic arterial infusion was more effective than intravenous infusion, and bone marrow-derived stem cells were more effective than those derived from the umbilical cord. Thirteen trials reported adverse events related to stem cell therapy, but no serious adverse events were reported.

Conclusions

Stem cell therapy is a safe and effective therapeutic option for CLD, while patients with ACLF benefit the most in terms of improved short-term survival. A single injection administration of bone marrow-derived stem cells via the hepatic artery has superior therapeutic effects.

PLK1 regulates hepatic stellate cell activation and liver fibrosis through Wnt/β-catenin signalling pathway

As an outcome of chronic liver disease, liver fibrosis involves the activation of hepatic stellate cells (HSCs) caused by a variety of chronic liver injuries. It is important to explore approaches to inhibit the activation and proliferation of HSCs for the treatment of liver fibrosis. PLK1 is overexpressed in many human tumour cells and has become a popular drug target in tumour therapy. Therefore, further study of the function of PLK1 in the cell cycle is valid. In the present study, we found that PLK1 expression was elevated in primary HSCs isolated from CCl4 -induced liver fibrosis mice and LX-2 cells stimulated with TGF-β1. Knockdown of PLK1 inhibited α-SMA and Col1α1 expression and reduced the activation of HSCs in CCl4 -induced liver fibrosis mice and LX-2 cells stimulated with TGF-β1. We further showed that inhibiting the expression of PLK1 reduced the proliferation of HSCs and promoted HSCs apoptosis in vivo and in vitro. Furthermore, we found that the Wnt/β-catenin signalling pathway may be essential for PLK1-mediated HSCs activation. Together, blocking PLK1 effectively suppressed liver fibrosis by inhibiting HSC activation, which may provide a new treatment strategy for liver fibrosis.

Special Issue on "Cellular and Molecular Mechanisms Underlying the Pathogenesis of Hepatic Fibrosis"

This Special issue contains 48 contributions highlighting novel findings and current concepts in basic and clinical liver fibrosis research. These articles emphasize issues on pathogenesis, cellular mediators, modulators, molecular pathways, disease-specific therapies, scoring systems, as well as novel preclinical animal models for the study of liver fibrogenesis. This editorial aims to briefly summarize the content of these papers.