FDG PET can replace bone scintigraphy in primary staging of malignant lymphoma

Mitophagy and apoptosis mediated by ROS participate in AlCl3-induced MC3T3-E1 cell dysfunction

Aluminum (Al), as a common environmental pollutant, causes osteoblast (OB) dysfunction and then leads to Al-related bone diseases (ARBD). One of the mechanisms of ARBD is oxidative stress, which leads to an increase in the production of reactive oxygen species (ROS). ROS can induce mitochondrial damage, thereby inducing mitophagy and apoptosis. But whether mitophagy and apoptosis mediated by ROS, and the role of ROS in AlCl₃-induced MC3T3-E1 cell dysfunction is still unclear. In this study, MC3T3-E1 cells used 0 mM Al (control group), 2 mM Al (Al group), 5 mM N-acetyl cysteine (NAC) (NAC group), 2 mM Al and 5 mM NAC (Al + NAC group) for 24 h. We found AlCl₃-induced MC3T3-E1 cell dysfunction accompanied by oxidative stress, apoptosis, and mitophagy. While NAC, a ROS scavenger treatment, restored cell function and alleviated the mitophagy and apoptosis. These results suggested that mitophagy and apoptosis mediated by ROS participate in AlCl₃-induced MC3T3-E1 cell dysfunction.

Primary bone anaplastic lymphoma kinase positive anaplastic large-cell lymphoma: A case report and review of the literature

BACKGROUND

Primary bone lymphoma (PBL) is an uncommon extranodal disease that represents approximately 1%-3% of lymphomas. Anaplastic lymphoma kinase (ALK) positive anaplastic large-cell lymphoma (ALCL) is an extremely rare type of PBL. The aim of this report is describe the symptoms, diagnosis, and treatment of primary bone ALK-positive ALCL.

CASE SUMMARY

A 66-year-old man presented to our hospital with neck and shoulder pain and intermittent fever that lasted for 1 mo. After extensive evaluation, positron emission tomography-computed tomography (CT) examination showed multiple osteolytic bone lesions without other sites lesions. CT-guided biopsy of the T10 vertebral body was performed, and the pathology results showed that neoplastic cells were positive for ALK-1, CD30, and CD3. A diagnosis of primary bone ALK positive ALCL was ultimately made. The patient was in partial response after four cycle soft cyclophosphamide, doxorubicin, vincristine, and prednisone chemotherapy, and we planned to repeat the biopsy and radiological examination after completion of the fifth cycle of therapy.

CONCLUSION

Primary bone ALK positive ALCL is a rare disease and physicians should keep in mind that ALCL can present with isolated osseous involvement without nodal involvement, and lymphoma should be considered in the differential diagnosis of primary bone lesions.

Induction of the differentiation of porcine bone marrow mesenchymal stem cells into premature hepatocyte-like cells in an indirect coculture system with primary hepatocytes

Liver transplantation is currently the only option for patients with end-stage liver disease. Thus, other alternate therapeutic strategies are needed. Bone marrow mesenchymal stem cells (BM-MSCs) are nonhematopoietic cells present in the bone marrow stroma that serve as precursors cells for various other cells. In this study, we evaluated the differentiation of porcine BM-MSCs into hepatocyte-like cells using three types of culture systems: hepatic induction medium (HIM), HIM/primary hepatocyte culture supernatant (HCS; 1:1 ratio), and a hepatocyte coculture system (HCCS; primary hepatocytes in the upper chamber, and BM-MSCs in the lower chamber). Primary hepatocytes were isolated from anesthetized healthy 1-month-old pigs by enzymatic digestion. Hepatic-specific marker expression (albumin [ALB], transferrin [TF], α-fetoprotein [AFP]), glycogen storage, low-density lipoprotein, and indocyanine green uptake were evaluated. Upregulation of hepatic-specific markers (ALB, TF, and AFP) was observed by real-time polymerase chain reaction in the HCCS group. Periodic acid-Schiff staining revealed enhanced glycogen storage in hepatocyte-like cells from the HCCS group compared with that from the HIM/HCS group. Furthermore, hepatocyte like-cells in the HCCS group showed improved LDL and ICG uptake than those in the other groups. Overall, our current study revealed that indirect coculture of primary hepatocytes and BM-MSCs enhanced the differentiation efficacy of BM-MSCs into hepatocyte-like cells by unknown useful soluble factors, including paracrine factors.

The peripheral CB1 receptor antagonist JD5037 attenuates liver fibrosis via a CB1 receptor/β-arrestin1/Akt pathway

BACKGROUND AND PURPOSE

Liver fibrosis is a serious cause of morbidity and mortality worldwide and has no adequate treatment. Accumulating evidence suggests that cannabinoid CB₁ receptors regulate a variety of physiological and pathological processes in the liver, and blockage of CB₁ receptor signalling shows promise as a new therapy for several liver diseases. The aim of this study was to investigate the potential therapeutic effects of CB₁ receptors and a peripheral CB₁ receptor antagonist JD5037 in liver fibrogenesis.

EXPERIMENTAL APPROACH

Liver samples from both humans and mouse models were investigated. The peripheral CB₁ receptor antagonist JD5037, β-arr1 wild type (β-arr1-WT) and β-arr1 knockout (β-arr1-KO) littermate models, and primary hepatic stellate cells (HSCs) were also used. The mechanisms underlying CB₁ receptor-regulated HSCs activation in fibrosis and the therapeutic potential of JD5037 were further analysed.

KEY RESULTS

CB₁ receptors were induced in samples from patients with liver fibrosis and from mouse models. These receptors promoted activation of HSCs in liver fibrosis via recruiting β-arrestin1 and Akt signalling, while blockage of CB₁ receptors with JD5037 attenuated CB₁ receptor-regulated HSCs activation and liver fibrosis by suppressing β-arrestin1/Akt signalling.

CONCLUSIONS AND IMPLICATIONS

CB₁ receptors promote the activation of HSCs and liver fibrosis via the β-arrestin1/Akt signalling pathway. The peripheral CB₁ receptor antagonist JD5037 blocked this pathway, the activation of HSCs and liver fibrosis. This compound and the associated pathway may be a novel approach to the treatment of liver fibrosis.

MicroRNA-134 deactivates hepatic stellate cells by targeting TGF-β activated kinase 1-binding protein 1

Aberrant expression of microRNAs is associated with liver fibrogenesis. We previously found that microRNA-134 (miR-134) expression was reduced in fibrosis-based hepatocarcinogenesis induced by diethylinitrosamine. Herein we investigate the role and mechanisms of miR-134 in hepatic fibrosis. Our data show that miR-134 expression is reduced in rat hepatic fibrogenesis induced by carbontetrachloride, bile duct ligation, and dimethylnitrosamine, as well as in activated hepatic stellate cells (HSCs). Moreover, miR-134 inhibited HSC proliferation, and decreased the expression of smooth muscle actin and collagen I in HSCs, whereas the miR-134 inhibitor increased HSC activation. MiR-134 also negatively regulated transforming growth factor-β-activated kinase 1-binding protein 1 (TAB1) expression in both human and rat HSCs by directly binding to its 3' untranslated region. Importantly, TAB1 expression was significantly elevated during liver fibrogenesis and HSC activation. Knockdown of TAB1 inhibited the proliferation and fibrogenic behavior of HSCs, and significantly reduced the effect of the miR-134 inhibitor on HSC proliferation. Collectively, these data suggest that miR-134 inhibits the activation of HSCs via directly targeting TAB1, and the restoration of miR-134 or targeting TAB1 is of clinical significance in the treatment of liver fibrosis.

Undifferentiated Adipose Tissue Stem Cell Transplantation Promotes Hepatic Regeneration, Ameliorates Histopathologic Damage of the Liver, and Upregulates the Expression of Liver Regeneration- and Liver-Specific Genes in a Rat Model of Partial Hepatectomy

Objective

Adipose tissue stem cells (ADSCs) present a promising therapeutic method to alleviate liver failure (LF). The purpose of this prospective study was to evaluate the efficacy of undifferentiated ADSC transplantation on liver regeneration and on the expression of liver regeneration- and liver-specific genes, following 60% partial hepatectomy (PHx).

Methods

Sixty female rats were subjected to PHx and were transplanted with 10⁶ or 2 × 10⁶ ADSCs, either into the portal vein (PV) or into the hepatic parenchyma. Animals of the control group were not transplanted and served as controls. Animals were sacrificed on the 4th, the 7th, or the 15th postoperative day (POD).

Results

The transplanted ADSCs were successfully engrafted into the liver parenchyma and ameliorated the histopathologic damage on the 7th and 15th POD. All transplanted animals demonstrated a significantly higher liver regeneration rate on the 4th and 7th POD, compared with the control group. The expression of hepatocyte growth factor, α-fetoprotein, tyrosine aminotransferase, hepatocyte nuclear factor 4a, and cytochrome P450 1A2 was significantly upregulated, compared with the control group.

Conclusions

Although undifferentiated, ADSC transplantation significantly enhanced the liver regeneration process. These findings may be proven clinically valuable, especially in cases of acute LF.

Engineering Embryonic Stem Cell Microenvironments for Tailored Cellular Differentiation

The rapid progress of embryonic stem cell (ESCs) research offers great promise for drug discovery, tissue engineering, and regenerative medicine. However, a major limitation in translation of ESCs technology to pharmaceutical and clinical applications is how to induce their differentiation into tailored lineage commitment with satisfactory efficiency. Many studies indicate that this lineage commitment is precisely controlled by the ESC microenvironment in vivo. Engineering and biomaterial-based approaches to recreate a biomimetic cellular microenvironment provide valuable strategies for directing ESCs differentiation to specific lineages in vitro. In this review, we summarize and examine the recent advances in application of engineering and biomaterial-based approaches to control ESC differentiation. We focus on physical strategies (e.g., geometrical constraint, mechanical stimulation, extracellular matrix (ECM) stiffness, and topography) and biochemical approaches (e.g., genetic engineering, soluble bioactive factors, coculture, and synthetic small molecules), and highlight the three-dimensional (3D) hydrogel-based microenvironment for directed ESC differentiation. Finally, future perspectives in ESCs engineering are provided for the subsequent advancement of this promising research direction.

Efficient generation of functional hepatocyte-like cells from mouse liver progenitor cells via indirect co-culture with immortalized human hepatic stellate cells

BACKGROUND

Differentiation of liver progenitor cells (LPCs) to functional hepatocytes holds great potential to develop new strategies for hepatocyte transplantation and the screening of drug-induced cytotoxicity. However, reports on the efficient and convenient hepatic differentiation of LPCs to hepatocytes are few. The present study aims to investigate the possibility of generating functional hepatocytes from LPCs in an indirect co-culture system.

METHODS

Mouse LPCs were co-cultured in Transwell plates with an immortalized human hepatic stellate cell line (HSC-Li) we previously established. The morphology, expression of hepatic markers, and functions of mouse LPC-derived cells were monitored and compared with those of conventionally cultured LPCs.

RESULTS

Co-culturing with HSC-Li cells induced differentiation of mouse LPCs into functional hepatocyte-like cells. The differentiated cells were morphologically transformed into hepatocyte-like cells 3 days after co-culture initiation. In addition, the differentiated cells expressed liver-specific genes and possessed hepatic functions, including glycogen storage, low-density lipoprotein uptake, albumin secretion, urea synthesis, and cytochrome P450 1A2 enzymatic activity.

CONCLUSIONS

Our method, which employs indirect co-culture with HSC-Li cells, can efficiently induce the differentiation of LPCs into functional hepatocytes. This finding suggests that this co-culture system can be a useful method for the efficient generation of functional hepatocytes from LPCs.

Liver progenitor cells-mediated liver regeneration in liver cirrhosis

Cirrhosis is defined as the histological development of regenerative nodules surrounded by fibrous bands in response to chronic liver injury. In cirrhotic liver where hepatocytes proliferation is compromised, liver progenitor cells (LPCs) are activated and then differentiated into hepatocytes and cholangiocytes, leading to the generation of regenerative nodules and functional restoration. Here, we summarize and discuss recent findings on the mechanisms underlying LPCs-mediated regeneration in liver cirrhosis. Firstly, we provide recent research on the mechanism underlying LPCs activation in severe or chronic liver injury. Secondly, we present new and exciting data on exploring the origin of LPCs, which reveal that the hepatocytes give rise to duct-like progenitors that then differentiate back into hepatocytes in chronic liver injury or liver cirrhosis. Finally, we highlight recent findings from the literature exploring the role of LPCs niche in directing the behavior and fate of LPCs. This remarkable insight into the cellular and molecular mechanisms of LPCs-mediated regeneration in liver cirrhosis will provide a basis for translating this knowledge into clinical application.

Optimization of mesenchymal stem cells (MSCs) delivery dose and route in mice with acute liver injury by bioluminescence imaging

PURPOSE

Both experimental and initial clinical studies have shown the therapeutic potential of mesenchymal stem cells (MSCs) in liver disease. Noninvasive tracking of MSCs could facilitate its clinical translation. The purpose of this study was to optimize MSCs delivery dose and route in mice with acute liver injury using bioluminescence imaging (BLI) to track the cells.

PROCEDURES

MSCs were labeled with the Luc2-mKate2 dual-fusion reporter gene (MSCs-R). The fate of MSCs-R was tracked through in vivo BLI after administration of different doses or delivery through different routes.

RESULTS

When delivered via the superior mesenteric vein (SMV), the high-dose (1.0 × 10(6) and 5.0 × 10(5)) group mice demonstrated high liver BLI signal but also had lethal portal vein embolization (PVE). By contrast, no PVE and its related death occurred in the low-dose (2.5 × 10(5)) group mice. Thus, 2.5 × 10(5) is the optimal delivery dose. Three delivery routes, i.e., inferior vena cava (IVC), SMV, and intrahepatic (IH) injection, were also systematically compared. After IVC infusion, MSCs-R were quickly trapped inside the lungs, and no detectable homing to the liver and other organs was observed. By IH injection, lung entrapment was bypassed, but MSCs-R distribution was only localized in the injection region of the liver. By contrast, after SMV infusion, MSCs-R were dispersedly distributed and stayed as long as 7-day posttransplantation in the liver. The in vivo imaging results were further validated by ex vivo imaging, digital subtraction angiography (DSA), and tissue analysis. Therefore, SMV is the optimal MSCs delivery route for liver disease.

CONCLUSIONS

Collectively, BLI, which could dynamically and quantitatively track cellular location and survival, is useful in determining MSCs transplantation parameters.

In vivo hepatogenic capacity and therapeutic potential of stem cells from human exfoliated deciduous teeth in liver fibrosis in mice

INTRODUCTION

Liver transplantation is a gold standard treatment for intractable liver diseases. Because of the shortage of donor organs, alternative therapies have been required. Due to their potential to differentiate into a variety of mature cells, stem cells are considered feasible cell sources for liver regeneration. Stem cells from human exfoliated deciduous teeth (SHED) exhibit hepatogenic capability in vitro. In this study, we investigated their in vivo capabilities of homing and hepatocyte differentiation and therapeutic efficacy for liver disorders in carbon tetrachloride (CCl4)-induced liver fibrosis model mice.

METHODS

We transplanted SHED into CCl4-induced liver fibrosis model mice through the spleen, and analyzed the in vivo homing and therapeutic effects by optical, biochemical, histological, immunological and molecular biological assays. We then sorted human leukocyte antigen-ABC (HLA-ABC)-positive cells from primary CCl4-damaged recipient livers, and analyzed their fusogenicity and hepatic characteristics by flow cytometric, genomic DNA, hepatocyte-specific gene assays. Furthermore, we examined the treatment effects of HLA-positive cells to a hepatic dysfunction by a secondary transplantation into CCl4-treated mice.

RESULTS

Transplanted SHED homed to recipient livers, and expressed HLA-ABC, human hepatocyte specific antigen hepatocyte paraffin 1 and human albumin. SHED transplantation markedly recovered liver dysfunction and led to anti-fibrotic and anti-inflammatory effects in the recipient livers. SHED-derived HLA-ABC-positive cells that were sorted from the primary recipient liver tissues with CCl4 damage did not fuse with the host mouse liver cells. Sorted HLA-positive cells not only expressed human hepatocyte-specific genes including albumin, cytochrome P450 1A1, fumarylacetoacetase, tyrosine aminotransferase, uridine 5'-diphospho-glucuronosyltransferase, transferrin and transthyretin, but also secreted human albumin, urea and blood urea nitrogen. Furthermore, SHED-derived HLA-ABC-positive cells were secondary transplanted into CCl4-treated mice. The donor cells homed into secondary recipient livers, and expressed hepatocyte paraffin 1 and human albumin, as well as HLA-ABC. The secondary transplantation recovered a liver dysfunction in secondary recipients.

CONCLUSIONS

This study indicates that transplanted SHED improve hepatic dysfunction and directly transform into hepatocytes without cell fusion in CCl4-treated mice, suggesting that SHED may provide a feasible cell source for liver regeneration.

In vitro culture of isolated primary hepatocytes and stem cell-derived hepatocyte-like cells for liver regeneration

Various liver diseases result in terminal hepatic failure, and liver transplantation, cell transplantation and artificial liver support systems are emerging as effective therapies for severe hepatic disease. However, all of these treatments are limited by organ or cell resources, so developing a sufficient number of functional hepatocytes for liver regeneration is a priority. Liver regeneration is a complex process regulated by growth factors (GFs), cytokines, transcription factors (TFs), hormones, oxidative stress products, metabolic networks, and microRNA. It is well-known that the function of isolated primary hepatocytes is hard to maintain; when cultured in vitro, these cells readily undergo dedifferentiation, causing them to lose hepatocyte function. For this reason, most studies focus on inducing stem cells, such as embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs), hepatic progenitor cells (HPCs), and mesenchymal stem cells (MSCs), to differentiate into hepatocyte-like cells (HLCs) in vitro. In this review, we mainly focus on the nature of the liver regeneration process and discuss how to maintain and enhance in vitro hepatic function of isolated primary hepatocytes or stem cell-derived HLCs for liver regeneration. In this way, hepatocytes or HLCs may be applied for clinical use for the treatment of terminal liver diseases and may prolong the survival time of patients in the near future.

Hepatic stellate cells promote the differentiation of embryonic stem cell-derived definitive endodermal cells into hepatic progenitor cells

AIM

Hepatic non-parenchymal cells are well known to be capable of providing an important microenvironment and growth factors for hepatic regeneration, but their capacity for directing embryonic stem cells (ESC) toward hepatocytes remains to be assessed. Thus, this study aims to investigate the role of hepatic stellate cells (HSC), the major type of hepatic non-parenchymal cells, in the differentiation of ESC as well as exploring the potentiality of ESC in regeneration medicine for cell-based therapy.

METHODS

A two-step differentiation procedure that utilized the capability of HSC to regulate proliferation and differentiation of hepatocytes was used to develop an approach for directing the differentiation of ESC towards hepatic progenitor cells. Mouse ESC were cultivated in a serum-free medium containing Activin A and fibroblast growth factor to generate definitive endodermal cells characterized by the CXCR4 cell-surface marker. After 6-8 days in culture, approximately 60% of the differentiated cells expressed CXCR4, and more than 90% of the CXCR4 positive cells could be recovered by cell sorting. The purified CXCR4 positive cells were co-cultured with mouse HSC as feeder cells in basal medium without additional hepatocyte growth factors. Differentiation was complete after 10-12 days of co-culture, and hepatic progenitor cell markers such as α-fetoprotein (afp) and albumin (alb) were detected in the terminally differentiated ESC.

CONCLUSION

These results show that HSC provide an appropriate microenvironment and pivotal growth factors for generation of hepatic progenitor cells from ESC-derived definitive endodermal cells, and suggest that this approach possibly allows for hepatic differentiation of ESC imitating the process of hepatic regeneration.

Therapeutic potentials occurring during the early differentiation process of mesenchymal stem cells in a rats model with thioacetamide-induced liver fibrosis

BACKGROUNDS/AIMS

Mesenchymal stem cells (MSCs) have the capacity to differentiate into hepatocytes, The purpose of this study is to investigate the MSCs' differentiation process and therapeutic potentials by comparing isolated MSCs with HGF-treated MSCs in rat's model with thiacetamide (TAA)-induced cirrhosis.

METHODS

Male Sprague-Dawley (SD) rats, weighing 100-150 g were used in this study. To induce liver fibrosis, recipient rats were taken with 0.04% thioacetamide (TAA) in the drinking water (400 mg TAA/L) for 8 weeks. The rats underlying liver cirrhosis were divided into 3 groups according to the transplanted materials, compared to normal saline as control (I) and isolated MSCs (II) HGF-treated MSCs.

RESULTS

Severe hepatic fibrosis and hepatocyte destruction were detected in the control group. Less hepatic cirrhosis and collagen formation, more hepatocyte regeneration and glycogen storage were detected in isolated MSCs compared to HGF-treated MSCs group, Distribution of red autofluorescence is mainly localized near the sinusoids in isolated MSCs, scattered away the sinusoids in HGF-treated MSCs group. MSCs transdifferentiated into CK-19 postive Oval cells and then to albulmin-producing hepatocytes, HGF treated MSCs differentiated into hepatocyte without the intermediate oval cells phase. HGF treated MSCs became the CK18-positive, MSCs became CD 90-positive.

CONCLUSIONS

Significant hepatocyte differentiation occurred in not HGF-treated MSCs but isolated MSCs group unexpectedly. These results suggest that the beneficial effect of MSCs on in rat's model with TAA-induced cirrhosis may occur during early differentiation course of MSCs. Mature hepatocyte itself has a little effect on the accelerated differentiation and functional capacity of hepatic lineage cell-line.

Hepatocyte differentiation of mesenchymal stem cells

BACKGROUND

Liver cell transplantation and bioartificial liver may provide metabolic support of liver function temporary and are prospective treatments for patients with liver failure. Mesenchymal stem cells (MSCs) are expected to be an ideal cell source for transplantation or liver tissue engineering, however the hepatic differentiation of MSCs is still insufficient for clinical application.

DATA SOURCES

A PubMed search on "mesenchymal stem cells", "liver cell" and "hepatocyte differentiation" was performed on the topic, and the relevant articles published in the past ten years were reviewed.

RESULTS

Hepatocyte-like cells differentiated from MSCs are a promising cell source for liver regeneration or tissue engineering. Although it is still a matter of debate as to whether MSC-derived hepatocytes may efficiently repopulate a host liver to provide adequate functional substitution, the majority of animal studies support that MSCs can become key players in liver-directed regenerative medicine. However the clinical application of human stem cells in the treatment of liver diseases is still in its infancy.

CONCLUSIONS

Future studies are required to improve the efficacy and consistency of hepatic differentiation from MSCs. It is necessary to better understand the mechanism to achieve transdifferentiation with high efficiency. More clinical trials are warranted to prove their efficacy in the management of patients with liver failure.

Tissue engineering of ureteral grafts by seeding urothelial differentiated hADSCs onto biodegradable ureteral scaffolds

The study is aimed to evaluate the differentiation potential of human adipose-derived stem cells (hADSCs) into urothelial lineage, and to assess possibility of constructing ureteral grafts using the differentiated hADSCs and a novel polylactic acid (PLA)/collagen scaffolds. HADSCs were indirectly cocultured with urothelial cells in a transwell coculture system for urothelial differentiation. After 14 days coculturing, differentiation was evaluated by detecting urothelial lineage markers (cytokeratin-18 and uroplakin 2) in mRNA and protein level. Then the differentiated hADSCs were seeded onto PLA/collagen ureteral scaffolds and cultured in vitro for 1 week. The biocompatibility of the scaffolds was tested by scanning electron microscopy (SEM) and MTT analysis. At last, the cell/scafflod grafts were subcutaneously implanted into 4-week-old female athymic mice for 14 days. The results demonstrated that the hADSCs could be efficiently induced into urothelial lineage by indirect coculture. The differentiated cells seeded onto the PLA/collagen ureteral scaffolds survived up to 7 days and maintained proliferation in vitro, which indicated that the scaffolds displayed good biocompatibility. In vivo study showed that the differentiated cells in the grafts survived, formed multiple layers on the scaffolds and expressed urothelial lineage markers. In conclusion, hADSCs may serve as an alternative cell resource in cell-based tissue engineering for ureteral reconstruction. These cells could be employed to construct a model of ureteral engineering grafts and be effectively applied in vivo, which could be a new strategy on ureteral replacement with applicable potential in clinical research.

Progress in research of differentiation of mesenchymal stem cells into functional hepatocytes

Mesenchymal stem cells (MSCs) are a group of stem cells deriving from mesodermal mesenchyme. They can be recovered from a variety of tissues, including bone marrow, umbilical cord tissue, umbilical cord blood, peripheral blood and adipose tissue. Under given conditions, MSCs can differentiate into bone, fat, nerve cells, hepatocytes and many other cells, and thus can be used as a new treatment to substitute for organ transplantation. In recent years, the incidence of end-stage liver disease has been increasing and it has become one of the major diseases affecting human health. Donor scarcity and immunological rejection limit the clinical application of liver transplantation. Numerous studies have confirmed the therapeutic effects of MSCs on hepatic fibrosis, cirrhosis and other liver diseases, which may be related to the differentiation of MSCs into functional hepatocytes. This paper reviews the capacity, regulation and molecular mechanism of MSC differentiation and discusses the therapeutic effects of different sources of stem cells for liver fibrosis.

Human umbilical cord mesenchymal stem cells improve liver function and ascites in decompensated liver cirrhosis patients

Decompensated liver cirrhosis (LC), a life-threatening complication of chronic liver disease, is one of the major indications for liver transplantation. Recently, mesenchymal stem cell (MSC) transfusion has been shown to lead to the regression of liver fibrosis in mice and humans. This study examined the safety and efficacy of umbilical cord-derived MSC (UC-MSC) in patients with decompensated LC. A total of 45 chronic hepatitis B patients with decompensated LC, including 30 patients receiving UC-MSC transfusion, and 15 patients receiving saline as the control, were recruited; clinical parameters were detected during a 1-year follow-up period. No significant side-effects and complications were observed in either group. There was a significant reduction in the volume of ascites in patients treated with UC-MSC transfusion compared with controls (P < 0.05). UC-MSC therapy also significantly improved liver function, as indicated by the increase of serum albumin levels, decrease in total serum bilirubin levels, and decrease in the sodium model for end-stage liver disease scores. UC-MSC transfusion is clinically safe and could improve liver function and reduce ascites in patients with decompensated LC. UC-MSC transfusion, therefore, might present a novel therapeutic approach for patients with decompensated LC.

Implications of the immunoregulatory functions of mesenchymal stem cells in the treatment of human liver diseases

Transplantation of mesenchymal stem cells (MSCs) has been recently studied in animal models, and in clinical trials of patients with fulminant hepatic failure, end-stage liver diseases and inherited metabolic disorders. Modulatory cytokines produced by MSCs can inhibit immunocyte proliferation and migration to the liver, thereby attenuating inflammatory injury and reducing hepatocyte apoptosis. In addition, MSCs play an important role in regressing liver fibrosis and in supporting the function, proliferation and differentiation of endogenous hepatocytes under appropriate conditions. Although remarkable progress has been achieved in basic and clinical MSC studies, optimal therapeutic regimens for the clinical application of MSCs, such as optimal doses, transplantation routine and interval period for transplantation, need to be elucidated in detail. Furthermore, the long-term safety and therapeutic efficacy of MSC transplantation should be evaluated in future clinical trials. This review summarizes our current understanding of the immunomodulatory effects of MSC therapies on human liver diseases.

Transcriptional profiling and hepatogenic potential of acute hepatic failure-derived bone marrow mesenchymal stem cells

Liver stem cell (LSC) transplantation is a promising alternate approach to liver transplantation for patients with end-stage liver disease. However, the precise origin of LSCs remains unclear. Herein we determine if bone marrow mesenchymal stem cells (BMSCs) isolated from rats in acute hepatic failure (AHF) possess hepatic characteristics and have differentiation potential. BMSCs were isolated from AHF and sham-operated rats, and primary hepatocytes were isolated from normal rats for comparison. The transcriptomic profile of BMSCs and primary hepatocytes was analyzed using the Affymetrix GeneChip Rat Genome 230 2.0 Array. BMSCs isolated from AHF and normal rats were induced to differentiate into hepatocytes in vitro and the degree of hepatic differentiation was assessed using quantitative real time RT-PCR, immunohistochemistry, and biochemical assays. AHF-derived BMSCs had a significantly different gene expression profile compared to control BMSCs. Thirty-four gene/probe sets were expressed in both AHF-derived BMSCs and primary hepatocytes, but were absent in control-derived BMSCs, including 3 hepatocyte-specific genes. Forty-four genes were up-regulated more than 2-fold in AHF-derived BMSCs compared to controls, including 3 genes involved in hepatocyte metabolism and development. Furthermore, AHF-derived BMSCs expressed more hepatocyte related genes than control BMSCs. Additional experiments to validate the differentiation of AHF-derived BMSCs, compared to control-derived BMSCs, showed that several hepatocyte-specific genes and proteins [such as albumin (ALB) and alpha fetoprotein (AFP)] were expressed earlier, and at higher levels, after 1 week of differentiation. Hepatocyte-specific metabolic functions were also significantly higher in the AHF group compared to control cells.

CONCLUSION

AHF-derived BMSCs had a hepatic transcriptional profile and expressed hepatocyte specific genes early during differentiation, and possessed greater hepatogenic potency in vitro compared to cells isolated from control animals, further confirming their potential as a stem cell-based therapy for end-stage liver disease.

Mesenchymal stem cells as therapeutic tools and gene carriers in liver fibrosis and hepatocellular carcinoma

Mesenchymal stem (stromal) cells (MSCs) are a source of circulating progenitors that are able to generate cells of all mesenchymal lineages and to cover cellular demands of injured tissues. The extent of their transdifferentiation plasticity remains controversial. Cells with MSC properties have been obtained from diverse tissues after purification and expansion in vitro. These cellular populations are heterogeneous and under certain conditions show pluripotent-like properties. MSCs present immunosuppressive and anti-inflammatory features and high migratory capacity toward inflamed or remodeling tissues. In this study we review available data regarding factors and signaling axes involved in the chemoattraction and engraftment of MSCs to an injured tissue or to a tissue undergoing active remodeling. Moreover, experimental evidence in support of uses of MSCs as vehicles of therapeutic genes is discussed. Because of its regenerative capacity and its particular immune properties, the liver is a good model to analyze the potential of MSC-based therapies. Finally, the potential application of MSCs and genetically modified MSCs in liver fibrosis and hepatocellular carcinoma (HCC) is proposed in view of available evidence.

The role of stem cells in liver repair and fibrosis

In response to liver injury or loss of liver mass, proliferation of mature liver cells is the first-line defense to restore liver homeostasis. In the setting of chronic liver disease, however, the ability of hepatocytes and cholangiocytes to proliferate is blocked and small bipotential progenitor cells are activated. Recent studies have established the role of these facultative progenitor cells in injury repair and fibrosis in patients with chronic liver disease and in experimental models. Several signaling pathways linking progenitor cell activation and fibrosis have been identified, and there is increasing evidence that cross-talk (both physical and via soluble factors) between progenitor cells and myofibroblasts is essential for both fibrosis and parenchymal regeneration. Even more exciting are new data examining the cellular components of the progenitor cell niche, demonstrating that both resident liver cells and circulating cells from the bone marrow can function as stem cells, suggesting that there is a surprising degree of phenotypic plasticity such that progenitor cells can contribute to the myofibroblast population and vice versa. We highlight here recent findings from the literature demonstrating the cellular and functional complexity of the progenitor cell niche, and emphasize some of the important questions that remain to drive future research.

Cell-to-cell contact induces human adipose tissue-derived stromal cells to differentiate into urothelium-like cells in vitro

Human adipose-derived stromal cells (hASCs) are capable of multi-lineage differentiation. Co-culture of stem cells with mature cells or tissues can drive their differentiation toward required lineages. We investigated whether direct cell-to-cell contact between hASCs and human UCs, or soluble signaling molecules, could induce the differentiation of hASCs into urothelium-like cells in vitro. hASCs were isolated from human subcutaneous adipose tissue and amplified in vitro. After labeled by green fluorescent protein, hASCs were cultured with human UCs in direct co-culture, indirect co-culture and conditioned culture, respectively. Two weeks later, expressions of specific urothelial differentiation markers were analyzed by RT-PCR and immunofluorescence. We found that hASCs in direct co-culture expressed urothelial-specific genes uroplakin Ib, uroplakin II and cytokeratin 18. However, uroplakin III gene was not detected during the experimental period. Additionally, uroplakin Ib and cytokeratin 18 were observed in differentiated hASCs by immunofluorescence. Notably, none of these markers were detected in hASCs cultured in indirect co-culture and conditioned culture. These findings suggest that direct cell-to-cell contact between hASCs and human UCs can induce the differentiation of hASCs along urothelial lineage.

Current status of stem cell therapy for liver diseases

Liver failure is one of the main causes of death worldwide and is a growing health problem. Since the discovery of stem cell populations capable of differentiating into specialized cell types, including hepatocytes, the possibility of their utilization in the regeneration of the damaged liver has been a focus of intense investigation. A variety of cell types were tested both in vitro and in vivo, but the definition of a more suitable cell preparation for therapeutic use in each type of liver lesions is yet to be determined. Here we review the protocols described for differentiation of stem cells into hepatocytes, the results of cell therapy in animal models of liver diseases, as well as the available data of the clinical trials in patients with advanced chronic liver disease.

Establishment of a three-dimensional co-culture system by porcine hepatocytes and bone marrow mesenchymal stem cells in vitro

AIM

The application of porcine hepatocytes in liver support systems has been hampered by the short-term survival. Co-cultivation of hepatocytes with non-parenchymal cells may be beneficial for optimizing cell functions via heterotypic interactions. In this study, we present a new cultivation system of porcine hepatocytes and mesenchymal stem cells (MSCs) in a randomly distributed co-culture manner.

METHODS

Mononuclear cells were isolated from bone marrow aspirate of swines (n = 3) by density gradient centrifugation. MSCs were characterized by flow cytometry with CD29, CD44, CD45 and CD90, respectively. Then freshly isolated hepatocytes were simultaneously inoculated with MSCs in a hepatocyte dominant manner. The morphological and functional changes of heterotypic interactions were characterized.

RESULTS

Ninety percent MSCs of passage 3 were positive for CD29, CD44 and CD90, but negative for CD45. A rapid attachment and self-organization of three-dimensional hepatocyte aggregates were encouraged. The cell ultrastructure indicating heterotypic junctions remained similar to that of hepatocytes in vivo. Fluorescence microscopy further verified that MSCs served as a feeder layer for hepatocyte aggregates. Hepatocyte performance levels such as albumin secretion, urea synthesis and CYP3A1 induction were all significantly enhanced in co-culture group compared with hepatocyte homo-culture (P < 0.05). The best hepatic function levels were achieved on day 2 and moderately decreased in the following co-culture days. Moreover, the cell cycle of hepatocytes manifested the same trend in parallel to the enhancement of hepatocyte functionality.

CONCLUSIONS

A three-dimensional co-culture system by porcine hepatocytes and bone marrow MSCs was for the first time established in vitro. Enhanced liver-specific functions make such a co-culture system a promising tool for tissue engineering, cell biology, and bioartificial liver devices.