Current protocols and clinical efficacy of human fetal liver cell therapy in patients with liver disease: A literature review

Hepatocyte-derived liver progenitor-like cells attenuate liver cirrhosis via induction of apoptosis in hepatic stellate cells

BACKGROUND

Cell therapy demonstrates promising potential as a substitute therapeutic approach for liver cirrhosis. We have developed a strategy to effectively expand murine and human hepatocyte-derived liver progenitor-like cells (HepLPCs) in vitro. The primary objective of the present study was to apply HepLPCs to the treatment of liver cirrhosis and to elucidate the underlying mechanisms responsible for their therapeutic efficacy.

METHODS

The effects of allogeneic or xenogeneic HepLPC transplantation were investigated in rat model of liver cirrhosis. Liver tissues were collected and subjected to immunostaining to assess changes in histology. In vitro experiments used HSCs to explore the antifibrotic properties of HepLPC-secretomes and their underlying molecular mechanisms. Additionally, proteomic analysis was conducted to characterize the protein composition of HepLPC-secretomes.

RESULTS

Transplantation of HepLPCs resulted in decreased active fibrogenesis and net fibrosis in cirrhosis models. Apoptosis of HSCs was observed in vivo after HepLPC treatment. HepLPC-secretomes exhibited potent inhibition of TGF-β1-induced HSC activation and promoted apoptosis through signal transducer and activator of transcription (STAT)1-mediated pathways in vitro. Furthermore, synergistic effects between amphiregulin and FGF19 within HepLPC-secretomes were identified, contributing to HSC apoptosis and exerting antifibrotic effects via activation of the janus kinase-STAT1 pathway.

CONCLUSIONS

HepLPCs have the potential to ameliorate liver cirrhosis by inducing STAT1-dependent apoptosis in HSCs. Amphiregulin and FGF19 are key factors responsible for STAT1 activation, representing promising novel therapeutic targets for the treatment of liver cirrhosis.

The Crosstalk between Mesenchymal Stromal/Stem Cells and Hepatocytes in Homeostasis and under Stress

Liver diseases, characterized by high morbidity and mortality, represent a substantial medical problem globally. The current therapeutic approaches are mainly aimed at reducing symptoms and slowing down the progression of the diseases. Organ transplantation remains the only effective treatment method in cases of severe liver pathology. In this regard, the development of new effective approaches aimed at stimulating liver regeneration, both by activation of the organ's own resources or by different therapeutic agents that trigger regeneration, does not cease to be relevant. To date, many systematic reviews and meta-analyses have been published confirming the effectiveness of mesenchymal stromal cell (MSC) transplantation in the treatment of liver diseases of various severities and etiologies. However, despite the successful use of MSCs in clinical practice and the promising therapeutic results in animal models of liver diseases, the mechanisms of their protective and regenerative action remain poorly understood. Specifically, data about the molecular agents produced by these cells and mediating their therapeutic action are fragmentary and often contradictory. Since MSCs or MSC-like cells are found in all tissues and organs, it is likely that many key intercellular interactions within the tissue niches are dependent on MSCs. In this context, it is essential to understand the mechanisms underlying communication between MSCs and differentiated parenchymal cells of each particular tissue. This is important both from the perspective of basic science and for the development of therapeutic approaches involving the modulation of the activity of resident MSCs. With regard to the liver, the research is concentrated on the intercommunication between MSCs and hepatocytes under normal conditions and during the development of the pathological process. The goals of this review were to identify the key factors mediating the crosstalk between MSCs and hepatocytes and determine the possible mechanisms of interaction of the two cell types under normal and stressful conditions. The analysis of the hepatocyte-MSC interaction showed that MSCs carry out chaperone-like functions, including the synthesis of the supportive extracellular matrix proteins; prevention of apoptosis, pyroptosis, and ferroptosis; support of regeneration; elimination of lipotoxicity and ER stress; promotion of antioxidant effects; and donation of mitochondria. The underlying mechanisms suggest very close interdependence, including even direct cytoplasm and organelle exchange.

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.