SDF-1/CXCR4 Axis Promotes MSCs to Repair Liver Injury Partially through Trans-Differentiation and Fusion with Hepatocytes

Leveraging stem cells to combat hepatitis: a comprehensive review of recent studies

Hepatitis is a significant global public health concern, with viral infections being the most common cause of liver inflammation. Antiviral medications are the primary treatments used to suppress the virus and prevent liver damage. However, the high cost of these drugs and the lack of awareness and stigma surrounding the disease create challenges in managing hepatitis. Stem cell therapy has arisen as a promising therapeutic strategy for hepatitis by virtue of its regenerative and immunomodulatory characteristics. Stem cells have the exceptional capacity to develop into numerous cell types and facilitate tissue regeneration, rendering them a highly promising therapeutic avenue for hepatitis. In animal models, stem cell therapy has demonstrated worthy results by reducing liver inflammation and improving liver function. Furthermore, clinical trials have been undertaken to assess the safety and effectiveness of stem cell therapy in individuals with hepatitis. This review aims to explore the involvement of stem cells in treating hepatitis and highlight the findings from studies conducted on both animals and humans. The objective of this review is to primarily concentrate on the ongoing and future clinical trials that assess the application of stem cell therapy in the context of hepatitis, including the transplantation of autologous bone marrow-derived stem cells, human induced pluripotent stem cells, and other mesenchymal stem cells. In addition, this review will explore the potential merits and constraints linked to stem cell therapy for hepatitis, as well as its prospective implications in the management of this disease.

Five Critical Gene-Based Biomarkers With Optimal Performance for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most fatal cancers in the world. There is an urgent need to understand the molecular background of HCC to facilitate the identification of biomarkers and discover effective therapeutic targets. Published transcriptomic studies have reported a large number of genes that are individually significant for HCC. However, reliable biomarkers remain to be determined. In this study, built on max-linear competing risk factor models, we developed a machine learning analytical framework to analyze transcriptomic data to identify the most miniature set of differentially expressed genes (DEGs). By analyzing 9 public whole-transcriptome datasets (containing 1184 HCC samples and 672 nontumor controls), we identified 5 critical differentially expressed genes (DEGs) (ie, CCDC107, CXCL12, GIGYF1, GMNN, and IFFO1) between HCC and control samples. The classifiers built on these 5 DEGs reached nearly perfect performance in identification of HCC. The performance of the 5 DEGs was further validated in a US Caucasian cohort that we collected (containing 17 HCC with paired nontumor tissue). The conceptual advance of our work lies in modeling gene-gene interactions and correcting batch effect in the analytic framework. The classifiers built on the 5 DEGs demonstrated clear signature patterns for HCC. The results are interpretable, robust, and reproducible across diverse cohorts/populations with various disease etiologies, indicating the 5 DEGs are intrinsic variables that can describe the overall features of HCC at the genomic level. The analytical framework applied in this study may pave a new way for improving transcriptome profiling analysis of human cancers.

Herpetin Promotes Bone Marrow Mesenchymal Stem Cells to Alleviate Carbon Tetrachloride-Induced Acute Liver Injury in Mice

Herpetin, an active compound derived from the seeds of Herpetospermum caudigerum Wall., is a traditional Tibetan herbal medicine that is used for the treatment of hepatobiliary diseases. The aim of this study was to evaluate the stimulant effect of herpetin on bone marrow mesenchymal stem cells (BMSCs) to improve acute liver injury (ALI). In vitro results showed that herpetin treatment enhanced expression of the liver-specific proteins alpha-fetoprotein, albumin, and cytokeratin 18; increased cytochrome P450 family 3 subfamily a member 4 activity; and increased the glycogen-storage capacity of BMSCs. Mice with ALI induced by carbon tetrachloride (CCl₄) were treated with a combination of BMSCs by tail-vein injection and herpetin by intraperitoneal injection. Hematoxylin and eosin staining and serum biochemical index detection showed that the liver function of ALI mice improved after administration of herpetin combined with BMSCs. Western blotting results suggested that the stromal cell-derived factor-1/C-X-C motif chemokine receptor 4 axis and the Wnt/β-catenin pathway in the liver tissue were activated after treatment with herpetin and BMSCs. Therefore, herpetin is a promising BMSC induction agent, and coadministration of herpetin and BMSCs may affect the treatment of ALI.

Mesenchymal stromal cells (MSCs) and their exosome in acute liver failure (ALF): a comprehensive review

Recently, mesenchymal stromal cells (MSCs) and their derivative exosome have become a promising approach in the context of liver diseases therapy, in particular, acute liver failure (ALF). In addition to their differentiation into hepatocytes in vivo, which is partially involved in liver regeneration, MSCs support liver regeneration as a result of their appreciated competencies, such as antiapoptotic, immunomodulatory, antifibrotic, and also antioxidant attributes. Further, MSCs-secreted molecules inspire hepatocyte proliferation in vivo, facilitating damaged tissue recovery in ALF. Given these properties, various MSCs-based approaches have evolved and resulted in encouraging outcomes in ALF animal models and also displayed safety and also modest efficacy in human studies, providing a new avenue for ALF therapy. Irrespective of MSCs-derived exosome, MSCs-based strategies in ALF include administration of native MSCs, genetically modified MSCs, pretreated MSCs, MSCs delivery using biomaterials, and also MSCs in combination with and other therapeutic molecules or modalities. Herein, we will deliver an overview regarding the therapeutic effects of the MSCs and their exosomes in ALF. As well, we will discuss recent progress in preclinical and clinical studies and current challenges in MSCs-based therapies in ALF, with a special focus on in vivo reports.

Emerging Importance of Chemokine Receptor CXCR4 and Its Ligand in Liver Disease

Chemokine receptors are members of the G protein-coupled receptor superfamily, which together with chemokine ligands form chemokine networks to regulate various cellular functions, immune and physiological processes. These receptors are closely related to cell movement and thus play a vital role in several physiological and pathological processes that require regulation of cell migration. CXCR4, one of the most intensively studied chemokine receptors, is involved in many functions in addition to immune cells recruitment and plays a pivotal role in the pathogenesis of liver disease. Aberrant CXCR4 expression pattern is related to the migration and movement of liver specific cells in liver disease through its cross-talk with a variety of significant cell signaling pathways. An in-depth understanding of CXCR4-mediated signaling pathway and its role in liver disease is critical to identifying potential therapeutic strategies. Current therapeutic strategies for liver disease mainly focus on regulating the key functions of specific cells in the liver, in which the CXCR4 pathway plays a crucial role. Multiple challenges remain to be overcome in order to more effectively target CXCR4 pathway and identify novel combination therapies with existing strategies. This review emphasizes the role of CXCR4 and its important cell signaling pathways in the pathogenesis of liver disease and summarizes the targeted therapeutic studies conducted to date.

Downregulation of augmenter of liver regeneration impairs the therapeutic efficacy of liver epithelial progenitor cells against acute liver injury by enhancing mitochondrial fission

Cell-based therapeutic approaches have been proven to be effective strategies for the treatment of acute liver injury (ALI). However, widespread application of these procedures is limited by several key issues, including rapid loss of stemness in vitro, aberrant differentiation into undesirable cell types, and low engraftment in vivo. In this study, liver epithelial progenitor cells (LEPCs) were characterized and transfected with augmenter of liver regeneration (ALR). The results revealed that in ALI mice with CCl₄ , the transplantation of ALR-bearing LEPCs into the liver markedly protected mice against ALI by decreasing the levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), thus relieving hepatic tissue injury and attenuating inflammatory infiltration. Mechanistically, the knockdown of ALR in LEPCs activated the phosphorylation of dynamin-related protein 1 (Drp1) at the S616 site and thereby enhanced mitochondrial fission. In contrast, the transfection of ALR into LEPCs significantly inhibited Drp1 phosphorylation, thereby favoring the maintenance of mitochondrial integrity and the preservation of adenosine triphosphate contents in LEPCs. Consequently, the ALR-bearing LEPCs transplanted into ALI mice exhibited substantially greater homing ability to the injured liver via the SDF-1/CXCR4 axis than that of LEPCs-lacking ALR. In conclusion, we demonstrated that the transplantation of ALR-transfected LEPCs protected mice against CCl₄ -induced ALI, thus offering immense curative potential in the clinic.

Mesenchymal Stem Cells Suppress TGF-β Release to Decrease α-SMA Expression in Ameliorating CCl4-Induced Liver Fibrosis

Introduction:

Liver fibrosis (LF) is the excessive deposition of extracellular matrix (ECM), produced by overactivated hepatic stellate cells, following prolonged transforming growth factor-β (TGF-β) stimulation. The ability of mesenchymal stem cells (MSCs) to improve LF has been reported. However, the mechanisms of MSCs to ameliorate LF through suppressing TGF-β and α-smooth muscle actin (α-SMA) remains unclear.

Aim:

To investigate the effects of MSCs treatment on suppressing TGF-β levels and decreasing α-SMA expression in an LF model.

Methods:

In this study, wenty-four male Wistar rats were injected intraperitoneal (IP) with carbon tetrachloride (CCL4), twice weekly, for eight weeks, to induce LF. Rats were randomly assigned to six groups: Sham, Control, Sham-lo, Sham-hi, and MSC-treated groups, at doses of 1 x 10⁶ (T1) and 2x10⁶ (T2) cells. TGF-β levels were analyzed by enzyme-linked immunosorbent assay (ELISA), whereas α-SMA expression was determined by immunohistochemistry staining.

Results:

MSCs decreased the expression of TGF-β in T1 and T2 groups on day 3 and 14. The T2 group showed lower TGF-β levels than that in the T1 group. This finding was in line with the observed decrease in α-SMA expression and the number of collagen.

Conclusion:

MSCs treatment ameliorated LF by suppressing TGF-β production, leading to decreased α-SMA expression in a CCL4-induced LF animal model.

Adipose-tissue derived porcine mesenchymal stem cells efficiently ameliorate CCl4-induced acute liver failure in mice

Adipose tissue derived mesenchymal stem cells (ADMSCs) may be an attractive therapeutic source for acute liver injury because of their high accessibility and non-invasiveness. Here, we investigated the therapeutic potentials of porcine ADMSCs for acute liver failure (ALF). The morphology, differentiation potential, expression patterns of cell surface markers and liver-specific genes were compared between the ADMSCs derived from the pigs with or without ALF. For therapeutic studies, the expanded porcine ADMSCs from either ALF pig (ALF-ADMSCs) or healthy control pig (Nor-ADMSCs) of passage 3 were transplanted into CCl₄-induced ALF mice, and the liver histology and functional tests were performed at days 1, 7, 14, and 21 after cell transplantation. ALF-ADMSCs expressed higher mRNA level of hepatic growth factor (HGF) than the Nor-ADMSCs. Both ALF-ADMSCs and Nor-ADMSCs improved liver histology, functions, and mouse survival rate. Higher level of porcine hepatocyte-specific genes was seen in the livers of ALF-ADMSCs transplanted mice as compared to the Nor-ADMSCs transplanted mice. In particular, ALF-ADMSCs transplanted mice expressed significantly higher level of albumin and cytokeratin 18 in the liver tissues as compared to the Nor-ADMSCs transplanted mice. ALF-ADMSCs might be superior to Nor-ADMSCs in the treatment of ALF as the former possesses stronger hepatic differentiation potential.

Redox Control of the Immune Response in the Hepatic Progenitor Cell Niche

The liver commonly self-regenerates by a proliferation of mature cell types. Nevertheless, in case of severe or protracted damage, the organ renewal is mediated by the hepatic progenitor cells (HPCs), adult progenitors capable of differentiating toward the biliary and the hepatocyte lineages. This regeneration process is determined by the formation of a stereotypical niche surrounding the emerging progenitors. The organization of the HPC niche microenvironment is crucial to drive biliary or hepatocyte regeneration. Furthermore, this is the site of a complex immunological activity mediated by several immune and non-immune cells. Indeed, several cytokines produced by monocytes, macrophages and T-lymphocytes may promote the activation of HPCs in the niche. On the other side, HPCs may produce pro-inflammatory cytokines induced by liver inflammation. The inflamed liver is characterized by high generation of reactive oxygen and nitrogen species, which in turn lead to the oxidation of macromolecules and the alteration of signaling pathways. Reactive species and redox signaling are involved in both the immunological and the adult stem cell regeneration processes. It is then conceivable that redox balance may finely regulate the immune response in the HPC niche, modulating the regeneration process and the immune activity of HPCs. In this perspective article, we summarize the current knowledge on the role of reactive species in the regulation of hepatic immunity, suggesting future research directions for the study of redox signaling on the immunomodulatory properties of HPCs.

Role of Granulocyte Colony-stimulating Factor Therapy in Cirrhosis, 'Inside Any Deep Asking Is the Answering'

Liver cirrhosis progresses through multiple clinical stages which culminate in either death or liver transplantation. Availability of organs, timely listing and prompt receipt of donor-livers pose difficulties in improving transplant-listed and transplant outcomes. In this regard, regenerative therapies, particularly with granulocyte colony-stimulating factor (GCSF), has become a lucrative option for improving transplant-free survival. However, the literature is confusing with regards to patient selection and real outcomes. In this exhaustive review, we describe the basics of liver fibrosis and cirrhosis through novel insights from a therapeutic point of view, discuss preclinical studies on GCSF in advanced liver disease to improve on clinical utility, shed light on the pertinent literature of GCSF in advanced cirrhosis, and provide astute inputs on growth factor therapy in decompensated cirrhosis.

The Emerging Role of Mesenchymal Stem Cells in Vascular Calcification

Vascular calcification (VC), characterized by hydroxyapatite crystal depositing in the vessel wall, is a common pathological condition shared by many chronic diseases and an independent risk factor for cardiovascular events. Recently, VC is regarded as an active, dynamic cell-mediated process, during which calcifying cell transition is critical. Mesenchymal stem cells (MSCs), with a multidirectional differentiation ability and great potential for clinical application, play a duplex role in the VC process. MSCs facilitate VC mainly through osteogenic transformation and apoptosis. Meanwhile, several studies have reported the protective role of MSCs. Anti-inflammation, blockade of the BMP2 signal, downregulation of the Wnt signal, and antiapoptosis through paracrine signaling are possible mechanisms. This review displays the evidence both on the facilitating role and on the protective role of MSCs, then discusses the key factors determining this divergence.

Liver Macrophage Depletion Ameliorates The Effect of Mesenchymal Stem Cell Transplantation in a Murine Model of Injured Liver

Mesenchymal stem cells (MSCs) therapy show different levels of effectiveness in the context of different types of liver damage, suggesting that the microenvironment of the injured liver is a key determinant for effective stem cell therapy. The objective was to assess the modulatory effect of hepatic stem cell niche components on the transplanted MSCs during liver injury induced by carbon tetrachloride (CCl₄). Superparamagnetic iron oxide (SPIO)-labeled human MSCs were injected intravenously into mice treated with CCl₄ and subjected to hepatic macrophage-depletion. Liver tissues were collected at different intervals post transplantation for subsequent histopathological, morphometric, immunohistochemical, gene expression and ultrastructural studies. The homing of the transplanted MSCs was evidenced by tracing them within the niche by iron staining and immunohistochemical studies. MSCs differentiated into hepatocyte-like cells and intimal smooth muscle cells as evidenced by their expression of human albumin and α-smooth muscle actin with a concomitant increase in the level of mouse hepatocyte growth factor. A post transplantation reduction in the liver fibro-inflammatory reaction was found and was promoted by liver macrophages depletion. Thus, it could be concluded from the present study that prior manipulation of the microenvironment is required to improve the outcome of the transplanted cells.

Mesenchymal Stem Cells: Miraculous Healers or Dormant Killers?

Mesenchymal Stem Cells (MSCs) are a heterogeneous population of fibroblast-like cells which maintain self-renewability and pluripotency to differentiate into mesodermal cell lineages. The use of MSCs in clinical settings began with high enthusiasm and the number of MSC-based clinical trials has been rising ever since. However; the very unique characteristics of MSCs that made them suitable to for therapeutic use, might give rise to unwanted outcomes, including tumor formation and progression. In this paper, we present a model of carcinogenesis initiated by MSCs, which chains together the tissue organization field theory, the stem cell theory, and the inflammation-cancer chain. We believe that some tissue resident stem cells could be leaked cells from bone marrow MSC pool to various injured tissue, which consequently transform and integrate in the host tissue. If the injury persists or chronic inflammation develops, as a consequence of recurring exposure to growth factors, cytokines, etc. the newly formed tissue from MSCs, which still has conserved their mesenchymal and stemness features, go through rapid population expansion, and nullify their tumor suppressor genes, and hence give rise to neoplastic cell (carcinomas, sarcomas, and carcino-sarcomas). Considering the probability of this hypothesis being true, the clinical and therapeutic use of MSCs should be with caution, and the recipients' long term follow-up seems to be insightful.

Steroid-Mediated Decrease in Blood Mesenchymal Stem Cells in Liver Transplant could Impact Long-Term Recovery

Orthotopic liver transplant (OLT) remains the standard of care for end stage liver disease. To circumvent allo-rejection, OLT subjects receive gluococorticoids (GC). We investigated the effects of GC on endogenous mesenchymal stem (stromal) cells (MSCs) in OLT. This question is relevant because MSCs have regenerative potential and immune suppressor function. Phenotypic analyses of blood samples from 12 OLT recipients, at pre-anhepatic, anhepatic and post-transplant (2 h, Days 1 and 5) indicated a significant decrease in MSCs after GC injection. The MSCs showed better recovery in the blood from subjects who started with relatively low MSCs as compared to those with high levels at the prehepatic phase. This drop in MSCs appeared to be linked to GC since similar change was not observed in liver resection subjects. In order to understand the effects of GC on decrease MSC migration, in vitro studies were performed in transwell cultures. Untreated MSCs could not migrate towards the GC-exposed liver tissue, despite CXCR4 expression and the production of inflammatory cytokines from the liver cells. GC-treated MSCs were inefficient with respect to migration towards CXCL12, and this correlated with retracted cytoskeleton and motility. These dysfunctions were partly explained by decreases in the CXCL12/receptor axis. GC-associated decrease in MSCs in OLT recipients recovered post-transplant, despite poor migratory ability towards GC-exposed liver. In total, the study indicated that GC usage in transplant needs to be examined to determine if this could be reduced or avoided with adjuvant cell therapy.

Cell fusion in the liver, revisited

There is wide agreement that cell fusion is a physiological process in cells in mammalian bone, muscle and placenta. In other organs, such as the cerebellum, cell fusion is controversial. The liver contains a considerable number of polyploid cells: They are commonly believed to originate by genome endoreplication, although the contribution of cell fusion to polyploidization has not been excluded. Here, we address the topic of cell fusion in the liver from a historical point of view. We discuss experimental evidence clearly supporting the hypothesis that cell fusion occurs in the liver, specifically when bone marrow cells were injected into mice and shown to rescue genetic hepatic degenerative defects. Those experiments-carried out in the latter half of the last century-were initially interpreted to show “transdifferentiation”, but are now believed to demonstrate fusion between donor macrophages and host hepatocytes, raising the possibility that physiologically polyploid cells, such as hepatocytes, could originate, at least partially, through homotypic cell fusion. In support of the homotypic cell fusion hypothesis, we present new data generated using a chimera-based model, a much simpler model than those previously used. Cell fusion as a road to polyploidization in the liver has not been extensively investigated, and its contribution to a variety of conditions, such as viral infections, carcinogenesis and aging, remains unclear.

Serum from CCl4-induced acute rat injury model induces differentiation of ADSCs towards hepatic cells and reduces liver fibrosis

Cellular therapies hold promise to alleviate liver diseases. This study explored the potential of allogenic serum isolated from rat with acute CCl₄ injury to differentiate adipose derived stem cells (ADSCs) towards hepatic lineage. Acute liver injury was induced by CCl₄ which caused significant increase in serum levels of VEGF, SDF1α and EGF. ADSCs were preconditioned with 3% serum isolated from normal and acute liver injury models. ADSCs showed enhanced expression of hepatic markers (AFP, albumin, CK8 and CK19). These differentiated ADSCs were transplanted intra-hepatically in CCl₄-induced liver fibrosis model. After one month of transplantation, fibrosis and liver functions (alkaline phosphatase, ALAT and bilirubin) showed marked improvement in acute injury group. Elevated expression of hepatic (AFP, albumin, CK 18 and HNF4a) and pro survival markers (PCNA and VEGF) and improvement in liver architecture as deduced from results of alpha smooth muscle actin, Sirius red and Masson's trichome staining was observed.

Hepatic progenitor cell activation in liver repair

The liver possesses an extraordinary ability to regenerate after injury. Hepatocyte-driven liver regeneration is the default pathway in response to mild-to-moderate acute liver damage. When replication of mature hepatocytes is blocked, facultative hepatic progenitor cells (HPCs), also referred to as oval cells (OCs) in rodents, are activated. HPC/OCs have the ability to proliferate clonogenically and differentiate into several lineages including hepatocytes and bile ductal epithelia. This is a conserved liver injury response that has been studied in many species ranging from mammals (rat, mouse, and human) to fish. In addition, improper HPC/OC activation is closely associated with fibrotic responses, characterized by myofibroblast activation and extracellular matrix production, in many chronic liver diseases. Matrix remodeling and metalloprotease activities play an important role in the regulation of HPC/OC proliferation and fibrosis progression. Thus, understanding molecular mechanisms underlying HPC/OC activation has therapeutic implications for rational design of anti-fibrotic therapies.

Immunoprofiling of Adult-Derived Human Liver Stem/Progenitor Cells: Impact of Hepatogenic Differentiation and Inflammation

Adult-derived human liver stem/progenitor cells (ADHLSCs) are, nowadays, developed as therapeutic medicinal product for the treatment of liver defects. In this study, the impact of hepatogenic differentiation and inflammation priming on the ADHLSCs' immune profile was assessed in vitro and compared to that of mature hepatocytes. The constitutive immunological profile of ADHLSCs was greatly different from that of hepatocytes. Differences in the expression of the stromal markers CD90 and CD105, adhesion molecules CD44 and CD49e, immunoregulatory molecules CD73 and HO-1, and NK ligands CD112 and CD155 were noted. While they globally preserved their immunological profile in comparison to undifferentiated counterparts, differentiated ADHLSCs showed a significant downregulation of CD200 expression as in hepatocytes. This was mainly induced by signals issued from EGF and OSM. On the other hand, the impact of inflammation was quite similar for all studied cell populations with an increased expression level of CD54 and CD106 and induction of that of CD40 and CD274. In conclusion, our immune profiling study suggests CD200 as a key factor in regulating the immunobiology of differentiated ADHLSCs. A better understanding of the molecular and physiological events related to such marker could help in designing the optimal conditions for an efficient therapeutic use of ADHLSCs.

Mesenchymal Stem Cell-Derived Extracellular Vesicles: Roles in Tumor Growth, Progression, and Drug Resistance

Mesenchymal stem cells (MSCs) are ubiquitously present in many tissues. Due to their unique advantages, MSCs have been widely employed in clinical studies. Emerging evidences indicate that MSCs can also migrate to the tumor surrounding stroma and exert complex effects on tumor growth and progression. However, the effect of MSCs on tumor growth is still a matter of debate. Several studies have shown that MSCs could favor tumor growth. On the contrary, other groups have demonstrated that MSCs suppressed tumor progression. Extracellular vesicles have emerged as a new mechanism of cell-to-cell communication in the development of tumor diseases. MSCs-derived extracellular vesicles (MSC-EVs) could mimic the effects of the mesenchymal stem cells from which they originate. Different studies have reported that MSC-EVs may exert various effects on the growth, metastasis, and drug response of different tumor cells by transferring proteins, messenger RNA, and microRNA to recipient cells. In the present review, we summarize the components of MSC-EVs and discuss the roles of MSC-EVs in different malignant diseases, including the related mechanisms that may account for their therapeutic potential. MSC-EVs open up a promising opportunity in the treatment of cancer with increased efficacy.

Combination of low-energy shock-wave therapy and bone marrow mesenchymal stem cell transplantation to improve the erectile function of diabetic rats

Stem cell transplantation and low-energy shock-wave therapy (LESWT) have emerged as potential and effective treatment protocols for diabetic erectile dysfunction. During the tracking of transplanted stem cells in diabetic erectile dysfunction models, the number of visible stem cells was rather low and decreased quickly. LESWT could recruit endogenous stem cells to the cavernous body and improve the microenvironment in diabetic cavernous tissue. Thus, we deduced that LESWT might benefit transplanted stem cell survival and improve the effects of stem cell transplantation. In this research, 42 streptozotocin-induced diabetic rats were randomized into four groups: the diabetic group (n = 6), the LESWT group (n = 6), the bone marrow-derived mesenchymal stem cell (BMSC) transplantation group (n = 15), and the combination of LESWT and BMSC transplantation group (n = 15). One and three days after BMSC transplantation, three rats were randomly chosen to observe the survival numbers of BMSCs in the cavernous body. Four weeks after BMSC transplantation, the following parameters were assessed: the surviving number of transplanted BMSCs in the cavernous tissue, erectile function, real-time polymerase chain reaction, and penile immunohistochemical assessment. Our research found that LESWT favored the survival of transplanted BMSCs in the cavernous body, which might be related to increased stromal cell-derived factor-1 expression and the enhancement of angiogenesis in the diabetic cavernous tissue. The combination of LESWT and BMSC transplantation could improve the erectile function of diabetic erectile function rats more effectively than LESWT or BMSC transplantation performed alone.

Muse Cells, Nontumorigenic Pluripotent-Like Stem Cells, Have Liver Regeneration Capacity Through Specific Homing and Cell Replacement in a Mouse Model of Liver Fibrosis

Muse cells, a novel type of nontumorigenic pluripotent-like stem cells, reside in the bone marrow, skin, and adipose tissue and are collectable as cells positive for pluripotent surface marker SSEA-3. They are able to differentiate into cells representative of all three germ layers. The capacity of intravenously injected human bone marrow-derived Muse cells to repair an immunodeficient mouse model of liver fibrosis was evaluated in this study. The cells exhibited the ability to spontaneously differentiate into hepatoblast/hepatocyte lineage cells in vitro. They demonstrated a high migration capacity toward the serum and liver section of carbon tetrachloride-treated mice in vitro. In vivo, they specifically accumulated in the liver, but not in other organs except, to a lesser extent, in the lungs at 2 weeks after intravenous injection in the liver fibrosis model. After homing, Muse cells spontaneously differentiated in vivo into HepPar-1 (71.1 ± 15.2%), human albumin (54.3 ± 8.2%), and anti-trypsin (47.9 ± 4.6%)-positive cells without fusing with host hepatocytes, and expressed mature functional markers such as human CYP1A2 and human Glc-6-Pase at 8 weeks after injection. Recovery in serum, total bilirubin, and albumin and significant attenuation of fibrosis were recognized with statistical differences between the Muse cell-transplanted group and the control groups, which received the vehicle or the same number of a non-Muse cell population of MSCs (MSCs in which Muse cells were eliminated). Thus, unlike ESCs and iPSCs, Muse cells are unique in their efficient migration and integration into the damaged liver after intravenous injection, nontumorigenicity, and spontaneous differentiation into hepatocytes, rendering induction into hepatocytes prior to transplantation unnecessary. They may repair liver fibrosis by two simple steps: expansion after collection from the bone marrow and intravenous injection. A therapeutic strategy such as this is feasible and may provide significant advancements toward liver regeneration in patients with liver disease.

Stromal cell-derived factor-1 (SDF-1) as a target in liver diseases

The chemokine stromal cell-derived factor-1 (SDF-1) or CXCL12 is constitutively expressed in healthy liver. However, its expression increases following acute or chronic liver injury. Liver sinusoidal endothelial cells (LSEC), hepatic stellate cells (HSC), and malignant hepatocytes are important sources of SDF-1/CXCL12 in liver diseases. CXCL12 is able to activate two chemokine receptors with different downstream signaling pathways, CXCR4 and CXCR7. CXCR7 expression is relevant on LSEC, while HSC, mesenchymal stem cells, and tumor cells mainly respond via CXCR4. Here, we summarize recent developments in the field of liver diseases involving this chemokine and its receptors. SDF-1-dependent signaling contributes to modulating acute liver injury and subsequent tissue regeneration. By activating HSC and recruiting mesenchymal cells from bone marrow, CXCL12 can promote liver fibrosis progression, while CXCL12-CXCR7 interactions endorse proregenerative responses in chronic injury. Moreover, the SDF-1 pathway is linked to development of hepatocellular carcinoma (HCC) by promoting tumor growth, angiogenesis, and HCC metastasis. High hepatic CXCR4 expression has been suggested as a biomarker indicating poor prognosis of HCC patients. Tumor-infiltrating myeloid-derived suppressor cells (MDSC) also express CXCR4 and migrate toward CXCL12. Thus CXCL12 inhibition might not only directly block HCC growth but also modulate the tumor microenvironment (angiogenesis, MDSC), thereby sensitizing HCC patients to conventional or emerging novel cancer therapies (e.g., sorafenib, regorafenib, nivolumab, pembrolizumab). We herein summarize the current knowledge on the complex interplay between CXCL12 and CXCR4/CXCR7 in liver diseases and discuss approaches on the therapeutic targeting of these axes in hepatitis, fibrosis, and liver cancer.

Identification of Pathways in Liver Repair Potentially Targeted by Secretory Proteins from Human Mesenchymal Stem Cells

BACKGROUND

The beneficial impact of mesenchymal stem cells (MSC) on both acute and chronic liver diseases has been confirmed, although the molecular mechanisms behind it remain elusive. We aim to identify factors secreted by undifferentiated and hepatocytic differentiated MSC in vitro in order to delineate liver repair pathways potentially targeted by MSC.

METHODS

Secreted factors were determined by protein arrays and related pathways identified by biomathematical analyses.

RESULTS

MSC from adipose tissue and bone marrow expressed a similar pattern of surface markers. After hepatocytic differentiation, CD54 (intercellular adhesion molecule 1, ICAM-1) increased and CD166 (activated leukocyte cell adhesion molecule, ALCAM) decreased. MSC secreted different factors before and after differentiation. These comprised cytokines involved in innate immunity and growth factors regulating liver regeneration. Pathway analysis revealed cytokine-cytokine receptor interactions, chemokine signalling pathways, the complement and coagulation cascades as well as the Januskinase-signal transducers and activators of transcription (JAK-STAT) and nucleotide-binding oligomerization domain-like receptor (NOD-like receptor) signalling pathways as relevant networks. Relationships to transforming growth factor β (TGF-β) and hypoxia-inducible factor 1-α (HIF1-α) signalling seemed also relevant.

CONCLUSION

MSC secreted proteins, which differed depending on cell source and degree of differentiation. The factors might address inflammatory and growth factor pathways as well as chemo-attraction and innate immunity. Since these are prone to dysregulation in most liver diseases, MSC release hepatotropic factors, potentially supporting liver regeneration.

Melatonin Pretreatment Enhances the Homing of Bone Marrow-derived Mesenchymal Stem Cells Following Transplantation in a Rat Model of Liver Fibrosis

Background:

Bone marrow-derived mesenchymal stem cells (BMMSCs) transplantation has been considered as a promising milestone in liver fibrosis treatment. However, low amounts of homing are a major obstacle. We aimed to investigate the role of melatonin pretreatment in BMMSC homing into experimental liver fibrosis.

Methods:

BMMSCs were obtained, grown, propagated and preconditioned with 5 µM melatonin and analyzed for multipotency and immunophenotypic features at passage three. The cells were labelled with CM-Dil and infused into the rats received the i.p. injection of carbon tetrachloride (CCl₄) for five weeks to induce liver fibrosis. Animals were divided into two groups: One group received BMMSCs, whereas the other group received melatonin-pretreated BMMSCs (MT-BMMSCs). After cell injection at 72 h, animals were sacrificed, and the liver tissues were assessed for further evaluations: fibrosis using Masson’s trichrome and hematoxylin and eosin staining and homing using fluorescent microscopy and flow cytometry.

Results:

BMMSCs and MT-BMMSCs expressed a high level of CD44 but low levels of CD11b, CD45 and CD34 (for all P≤0.05) and were able to differentiate into adipocytes and Schwann cells. CCl₄ induction resulted in extensive collagen deposition, tissue disruption and fatty accumulation with no obvious difference between the two groups. There was a significant increase in homing of MT-BMMSCs in both florescent microscopy (P≤0.001) and flow cytometry (P≤0.01) assays, as compared with non-treated BMMSCs.

Conclusion:

This study indicates the improved homing potential of BMMSCs in pretreatment with melatonin. Therefore, this strategy may represent an applied approach for improving the stem cell therapy of liver fibrosis.