Current status of stem cell therapy for liver diseases

Hypoxia-Induced miR-210 Overexpression Promotes the Differentiation of Human-Induced Pluripotent Stem Cells to Hepatocyte-Like Cells on Random Nanofiber Poly-L-Lactic Acid/Poly (ε-Caprolactone) Scaffolds

An alternative treatment to liver transplantation includes the use of differentiated stem cells. Hypoxia has been shown to endow human-induced pluripotent stem cells (hiPSCs) with enhanced hepatic differentiation. We have investigated a new strategy for hepatocyte differentiation from hiPSCs using a three-step differentiation protocol with lentiviral overexpression of hypoxia-microRNA-210 of cells grown on a hybrid scaffold. We analyzed the transduction of the miR-210 lentiviral and definitive endoderm and pluripotency gene markers, including SRY-box 17 (SOX17), forkhead box A2 (FOXA2), and octamer-binding transcription factor 4 (OCT-4) by Real-Time PCR and fluorescent microscope. The scanning electron microscopy (SEM) examined the 3D cell morphological changes. Immunocytochemistry staining was used together with assays for aspartate aminotransferase, alanine aminotransferase, and urea secretion to analyze hepatocyte biomarkers and functional markers consisting of α-fetoprotein (AFP), low-density lipoprotein (LDL) uptake, fat accumulation, and glycogen. The flow cytometry analyzed the generation of reactive oxygen species (ROS). Compared to cells transfected with the blank lentiviral vectors as a control, overexpressing miR-210 was at higher levels in hiPSCs. The expression of endodermal genes and glycogen synthesis significantly increased in the differentiated lentiviral miR-210 cells without any differences regarding lipid storage level. Additionally, cells containing miR-210 showed a greater expression of ALB, LDL, AST, ALT, urea, and insignificant lower AFP and ROS levels after 18 days. However, SEM showed no significant differences between cells under the differentiation process and controls. In conclusion, the differentiation of hiPSCs to hepatocyte-like cells under hypoxia miR-210 may be a suitable method for cell therapy and regenerative medicine.

Therapeutic mesenchymal stromal stem cells: Isolation, characterization and role in equine regenerative medicine and metabolic disorders

Mesenchymal stromal cells (MSC) have become a popular treatment modality in equine orthopaedics. Regenerative therapies are especially interesting for pathologies like complicated tendinopathies of the distal limb, osteoarthritis, osteochondritis dissecans (OCD) and more recently metabolic disorders. Main sources for MSC harvesting in the horse are bone marrow, adipose tissue and umbilical cord blood. While the acquisition of umbilical cord blood is fairly easy and non-invasive, extraction of bone marrow and adipose tissue requires more invasive techniques. Characterization of the stem cells as a result of any isolation method, is also a crucial step for the confirmation of the cells' stemness properties; thus, three main characteristics must be fulfilled by these cells, namely: adherence, expression of a series of well-defined differentiation clusters as well as pluripotency. EVs, resulting from the paracrine action of MSCs, also play a key role in the therapeutic mechanisms mediated by stem cells; MSC-EVs are thus largely implicated in the regulation of proliferation, maturation, polarization and migration of various target cells. Evidence that EVs alone represent a complex network 0involving different soluble factors and could then reflect biophysical characteristics of parent cells has fuelled the importance of developing highly specific techniques for their isolation and analysis. All these aspects related to the functional and technical understanding of MSCs will be discussed and summarized in this review.

Bone Marrow-Derived Mesenchymal Stem Cells Isolated from Patients with Cirrhosis and Healthy Volunteers Show Comparable Characteristics

Background and Objectives

Autologous or allogeneic bone marrow-derived mesenchymal stem cells (BMSCs) have been applied in clinical trials to treat liver disease. However, only a few studies are comparing the characteristics of autologous MSCs from patients and allogeneic MSCs from normal subjects.

Methods and Results

We compared the characteristics of BMSCs (BCs and BPs, respectively) isolated from six healthy volunteers and six patients with cirrhosis. In passage 3 (P3), senescent population and expression of p53 and p21 were slightly higher in BPs, but the average population doubling time for P3–P5 in BPs was approximately 65.3±11.1 h, which is 18.4 h shorter than that in BCs (83.7±9.2 h). No difference was observed in the expression of CD73, CD90, or CD105 between BCs and BPs. Adipogenic differentiation slightly increased in BCs, but the expression levels of leptin, peroxisome proliferator-activated receptor γ, and CCAAT-enhancer-binding protein α did not vary between differentiated BCs and BPs. While ATP and reactive oxygen species levels were slightly lower in BPs, mitochondrial membrane potential, oxygen consumption rate, and expression of mitochondria-related genes such as cytochrome c oxidase 1 were not significantly different between BCs and BPs.

Conclusions

Taken together, there are marginal differences in the proliferation, differentiation, and mitochondrial activities of BCs and BPs, but both BMSCs from patients with cirrhosis and healthy volunteers show comparable characteristics.

Sex-Specific Transcriptome Differences in Human Adipose Mesenchymal Stem Cells

In humans, sexual dimorphism can manifest in many ways and it is widely studied in several knowledge fields. It is increasing the evidence that also cells differ according to sex, a correlation still little studied and poorly considered when cells are used in scientific research. Specifically, our interest is on the sex-related dimorphism on the human mesenchymal stem cells (hMSCs) transcriptome. A systematic meta-analysis of hMSC microarrays was performed by using the Transcriptome Mapper (TRAM) software. This bioinformatic tool was used to integrate and normalize datasets from multiple sources and allowed us to highlight chromosomal segments and genes differently expressed in hMSCs derived from adipose tissue (hADSCs) of male and female donors. Chromosomal segments and differentially expressed genes in male and female hADSCs resulted to be related to several processes as inflammation, adipogenic and neurogenic differentiation and cell communication. Obtained results lead us to hypothesize that the donor sex of hADSCs is a variable influencing a wide range of stem cell biologic processes. We believe that it should be considered in biologic research and stem cell therapy.

Mesenchymal stem cells to treat liver diseases

Mesenchymal stem cells (MSCs) are being developed for stem cell therapy and can be efficiently used in regenerative medicine. To date, more than 1,000 clinical trials have used MSCs; of these, more than 80 clinical trials have targeted liver disease. MSCs migrate to damaged liver tissues, differentiate into hepatocytes, reduce liver inflammatory responses, reduce liver fibrosis, and act as antioxidants. According to the reported literature, MSCs are safe, have no side effects, and improve liver function; however, their regenerative therapeutic effects are unsatisfactory. Here, we explain, in detail, the basic therapeutic effects and recent clinical advances of MSCs. Furthermore, we discuss future research directions for improving the regenerative therapeutic effects of MSCs.

Early Developmental Zebrafish Embryo Extract to Modulate Senescence in Multisource Human Mesenchymal Stem Cells

Stem cells undergo senescence both in vivo, contributing to the progressive decline in self-healing mechanisms, and in vitro during prolonged expansion. Here, we show that an early developmental zebrafish embryo extract (ZF1) could act as a modulator of senescence in human mesenchymal stem cells (hMSCs) isolated from both adult tissues, including adipose tissue (hASCs), bone marrow (hBM-MSCs), dental pulp (hDP-MSCs), and a perinatal tissue such as the Wharton’s Jelly (hWJ-MSCs). In all the investigated hMSCs, ZF1 decreased senescence-associated β-galactosidase (SA β-gal) activity and enhanced the transcription of TERT, encoding the catalytic telomerase core. In addition, it was associated, only in hASCs, with a transcriptional induction of BMI1, a pleiotropic repressor of senescence. In hBM-MSCs, hDP-MSCs, and hWJ-MSCs, TERT over-expression was concomitant with a down-regulation of two repressors of TERT, TP53 (p53), and CDKN1A (p21). Furthermore, ZF1 increased the natural ability of hASCs to perform adipogenesis. These results indicate the chance of using ZF1 to modulate stem cell senescence in a source-related manner, to be potentially used as a tool to affect stem cell senescence in vitro. In addition, its anti-senescence action could also set the basis for future in vivo approaches promoting tissue rejuvenation bypassing stem cell transplantation.

Comparison of Oxidative Stress Effects on Senescence Patterning of Human Adult and Perinatal Tissue-Derived Stem Cells in Short and Long-term Cultures

Human Mesenchymal Stem Cells (hMSCs) undergo senescence in lifespan. In most clinical trials, hMSCs experience long-term expansion ex vivo to increase cell number prior to transplantation, which unfortunately leads to cell senescence, hampering post-transplant outcomes. Hydrogen peroxide (H₂O₂) in vitro represents a rapid, time and cost-effective tool, commonly used as oxidative stress tantalizing the stem cell ability to cope with a hostile environment, recapitulating the onset and progression of cellular senescence. Here, H₂O₂ at different concentrations (ranging from 50 to 400 μM) and time exposures (1 or 2 hours - h), was used for the first time to compare the behavior of human Adipose tissue-derived Stem Cells (hASCs) and human Wharton's Jelly-derived MSCs (hWJ-MSCs), as representative of adult and perinatal tissue-derived stem cells, respectively. We showed timely different responses of hASCs and hWJ-MSCs at low and high subculture passages, concerning the cell proliferation, the cell senescence-associated β-Galactosidase activity, the capability of these cells to undergo passages, the morphological changes and the gene expression of tumor protein p53 (TP53, alias p53) and cyclin dependent kinase inhibitor 1A (CDKN1A, alias p21) post H₂O₂ treatments. The comparison between the hASC and hWJ-MSC response to oxidative stress induced by H₂O₂ is a useful tool to assess the biological mechanisms at the basis of hMSC senescence, but it could also provide two models amenable to test in vitro putative anti-senescence modulators and develop anti-senescence strategies.

Cell transplantation as a non-invasive strategy for treating liver fibrosis

Advancements in antiviral drugs have enabled control of viral hepatitis; yet, many patients with liver cirrhosis (LC) are awaiting liver transplants. Liver transplantation yields dramatic therapeutic effects, but problems such as shortage of donors, surgical invasiveness, immunological rejection and costs, limit the number of transplantations. Advances in liver regeneration therapy through cell transplantation as a non-invasive treatment for cirrhosis will supplement these restrictions to the number of liver transplants. Clinical trials for LC have included hematopoietic stem cell mobilization by administration of granulocyte colony-stimulating factor, infusion of autologous bone marrow cells, and administration of autologous mesenchymal stem cells derived from bone marrow or umbilical cord. Several recently reported randomized controlled studies have shown the effectiveness of these approaches. However, to promote implementation of new liver regeneration therapies, it is important to develop a system whereby cell therapies with ensured safety can be approved quickly.

Evaluation of phenotypic, functional and molecular characteristics of porcine mesenchymal stromal/stem cells depending on donor age, gender and tissue source

The biological properties of mesenchymal stem cells (MSCs) are influenced by donor age, gender and/or tissue sources. The present study investigated the cellular and molecular properties of porcine mesenchymal stromal/stem cells (MSCs) isolated from different tissues (adipose & dermal skin) and sex at different ages (1 week & 8 months after birth) with similar genetic and environmental backgrounds. MSCs were analyzed for alkaline phosphatase (AP) activity, CD90 and Oct3/4 expression, in vitro differentiation ability, senescence-associated β-galactosidase (SA-β-Gal) activity, telomeric properties, cell cycle status and expression of senescence (IL6, c-myc, TGFβ, p53 and p21)- and apoptosis (Bak and Bcl2)-related proteins. An age-dependent decline in AP activity and adipogenesis was observed in all MSCs, except for male A-MSCs. CD90 expression did not change, but SA-β-Gal activity increased with advancement in age, except in A-MSCs. Telomeric properties were similar in all MSCs, whereas expression levels of Oct3/4 protein declined with the advancement in age. p21 expression was increased with increase in donor age. Male derived cells have shown higher IL6 expression. The expression of p53 was slightly lower in MSCs of dermal tissue than in adipose tissue. Bak was expressed in all MSCs regardless of age, but up regulation of Bcl2 was observed in DS-MSCs derived at 1 week after birth. In conclusion, adipose tissue-derived MSCs from young female individuals were found to be more resistant to senescence under in vitro culture conditions.

Mesenchymal stem cell therapy for cirrhosis: Present and future perspectives

Cirrhosis occurs as a result of various chronic liver injuries, which may be caused by viral infections, alcohol abuse and the administration of drugs and chemicals. Recently, bone marrow cells (BMCs), hematopoietic stem cells (HSCs) and mesenchymal stem cells (MSCs) have been used for developing treatments for cirrhosis. Clinical trials have investigated the therapeutic potential of BMCs, HSCs and MSCs for the treatment of cirrhosis based on their potential to differentiate into hepatocytes. Although the therapeutic mechanisms of BMC, HSC and MSC treatments are still not fully characterized, the evidence thus far has indicated that the potential therapeutic mechanisms of MSCs are clearer than those of BMCs or HSCs with respect to liver regenerative medicine. MSCs suppress inflammatory responses, reduce hepatocyte apoptosis, increase hepatocyte regeneration, reverse liver fibrosis and enhance liver functionality. This paper summarizes the clinical studies that have used BMCs, HSCs and MSCs in patients with liver failure or cirrhosis. We also present the potential therapeutic mechanisms of BMCs, HSCs and MSCs for the improvement of liver function.

Changes in biochemical markers of liver fibrosis in patients with decompensated liver cirrhosis after autologous bone marrow stem cell infusion

AIM: To evaluate the effect of autologous bone marrow stem cell infusion on biochemical markers of liver fibrosis in patients with decompensated liver cirrhosis.

METHODS: Fifty patients with decompensated liver cirrhosis were included in the study. The bone marrow harvested from the ilium of patients was isolated and purified, and the final bone marrow stem cells were administered via the hepatic artery. The levels of biochemical markers of liver fibrosis were examined before transplantation, 4 and 8 wk after transplantation. Clinical manifestations and complications of transplantation were recorded during the follow-up period.

RESULTS: The level of serum albumin and the extent of ascites were improved significantly at 4 and 8 wk after transplantation than before transplantation (P < 0.05). The levels of serum alanine aminotransferase, total bilirubin, and prothrombin activity were improved after transplantation, however, the changes were not statistically significant (P > 0.05). Biochemical markers of liver fibrosis such as procollagen type Ⅲ, type Ⅳ collagen, laminin, and hyaluronic acid enzyme were decreased after treatment, of which procollagen type Ⅲ and hyaluronic acid enzyme were improved significantly (P < 0.05).

CONCLUSION: Biochemical markers of liver fibrosis are improved in patients with decompensated liver cirrhosis after autologous bone marrow stem cell infusion.

Comparison of proliferation and differentiation potential between mouse primary hepatocytes and embryonic hepatic progenitor cells in vitro

Cell therapy may be a novel and effective treatment strategy for liver diseases, replacing liver transplantation. The potential of two alternative cell types (hepatic progenitor/stem cells and mature hepatocytes) has not yet been fully assessed; the issues of low amplification efficiency and recovery function remain to be resolved. In this study, we investigated the proliferation, differentiation and function of primary mouse mature hepatocytes and embryonic hepatic progenitor cells. Primary cells were obtained from the livers of mouse embryos at 14.5 days post coitus [hepatic progenitor 14.5d (HP14.5d) cells], as well as from the livers of 3-month-old mice [liver cells 3m (LC3m)]. Using trypan blue staining and crystal violet staining to detect cell viability, we found that compared with the limited growth capability of primary LC3m cells, primary HP14.5d cells exhibited an active cell proliferation; however, proliferative ability of passaged HP14.5d cells significantly decreased. After the HP14.5d cells were treated in hepatic induction medium, the expression of progenitor cell markers decreased and that of mature hepatic markers increased, to levels similar to those of LC3m cells. On day 12 of induction, the HP14.5d cells showed comparable indocyanine green (ICG) uptake and glycogen storage to that of the LC3m cells. Therefore, our study demonstrates that primary hepatic progenitor cells have a stronger proliferation capacity and differentiation potential, supporting their clinical application in liver cell transplantation.

Granulocyte-colony stimulating factor therapy improves survival in patients with hepatitis B virus-associated acute-on-chronic liver failure

AIM: To evaluate the safety and efficacy of granulocyte-colony stimulating factor (G-CSF) therapy in patients with hepatitis B virus (HBV)-associated acute-on-chronic liver failure (ACLF).

METHODS: Fifty-five patients with HBV-associated ACLF were randomized into two groups: the treatment group and the control group. Twenty-seven patients in the treatment group received G-CSF (5 μg/kg per day, six doses) treatment plus standard therapy, and 28 patients in the control group received standard therapy only. The peripheral CD34⁺ cell count was measured consecutively by flow cytometry. Circulating white blood cell count, biochemical parameters, and other clinical data of these patients were recorded and analyzed. All patients were followed up for a period of 3 mo to evaluate the changes in liver function and survival rate.

RESULTS: The peripheral neutrophil and CD34⁺ cell counts in the G-CSF group increased on day 3 from the onset of therapy, continued to rise on day 7, and remained elevated on day 15 compared to those of the control group. Child-Turcotte-Pugh score of patients in the treatment group was improved on day 30 from the onset of G-CSF therapy, compared to that in the controls (P = 0.041). Model for End-Stage of Liver Disease score of patients in the treatment group was improved on day 7 (P = 0.004) and remained high on day 30 from the onset of G-CSF therapy (P < 0.001) compared to that in controls. After 3 mo of follow-up observation, the survival rate in the treatment group (48.1%) was significantly higher than that in the control group (21.4%) (P = 0.0181).

CONCLUSION: G-CSF therapy promoted CD34⁺ cell mobilization in patients with HBV-associated ACLF, and improved the liver function and the survival rate of these patients.

Evaluation of a hybrid artificial liver module based on a spheroid culture system of embryonic stem cell-derived hepatic cells

Hybrid artificial liver (HAL) is an extracorporeal circulation system comprised of a bioreactor containing immobilized functional liver cells. It is expected to not only serve as a temporary liver function support system, but also to accelerate liver regeneration in recovery from hepatic failure. One of the most difficult problems in developing a hybrid artificial liver is obtaining an adequate cell source. In this study, we attempt to differentiate embryonic stem (ES) cells by hepatic lineage using a polyurethane foam (PUF)/spheroid culture in which the cultured cells spontaneously form spherical multicellular aggregates (spheroids) in the pores of the PUF. We also demonstrate the feasibility of the PUF-HAL system by comparing ES cells to primary hepatocytes in in vitro and ex vivo experiments. Mouse ES cells formed multicellular spheroids in the pores of PUF. ES cells expressed liver-specific functions (ammonia removal and albumin secretion) after treatment with the differentiation-promoting agent, sodium butyrate (SB). We designed a PUF-HAL module comprised of a cylindrical PUF block with many medium-flow capillaries for hepatic differentiation of ES cells. The PUF-HAL module cells expressed ammonia removal and albumin secretion functions after 2 weeks of SB culture. Because of high proliferative activity of ES cells and high cell density, the maximum expression level of albumin secretion function per unit volume of module was comparable to that seen in primary mouse hepatocyte culture. In the animal experiments with rats, the PUF-HAL differentiating ES cells appeared to partially contribute to recovery from liver failure. This outcome indicates that the PUF module containing differentiating ES cells may be a useful biocomponent of a hybrid artificial liver support system.

Cells and materials for liver tissue engineering

Liver transplantation is currently the most efficacious treatment for end-stage liver diseases. However, one main problem with liver transplantation is the limited number of donor organs that are available. Therefore, liver tissue engineering based on cell transplantation that combines materials to mimic the liver is under investigation with the goal of restoring normal liver functions. Tissue engineering aims to mimic the interactions among cells with a scaffold. Particular materials or a matrix serve as a scaffold and provide a three-dimensional environment for cell proliferation and interaction. Moreover, the scaffold plays a role in regulating cell maturation and function via these interactions. In cultures of hepatic lineage cells, regulation of cell proliferation and specific function using biocompatible synthetic, biodegradable bioderived matrices, protein-coated materials, surface-modified nanofibers, and decellularized biomatrix has been demonstrated. Furthermore, beneficial effects of addition of growth factor cocktails to a flow bioreactor or coculture system on cell viability and function have been observed. In addition, a system for growing stem cells, liver progenitor cells, and primary hepatocytes for transplantation into animal models was developed, which produces hepatic lineage cells that are functional and that show long-term proliferation following transplantation. The major limitation of cells proliferated with matrix-based transplantation systems is the high initial cell loss and dysfunction, which may be due to the absence of blood flow and the changes in nutrients. Thus, the development of vascular-like scaffold structures, the formation of functional bile ducts, and the maintenance of complex metabolic functions remain as major problems in hepatic tissue engineering and will need to be addressed to enable further advances toward clinical applications.

Bone marrow progenitor cells do not contribute to liver fibrogenic cells

AIM

To investigate the contribution of bone marrow (BM) cells to hepatic fibrosis.

METHODS

To establish a model of chimerism, C57Bl/6 female mice were subjected to full-body irradiation (7 Gy) resulting in BM myeloablation. BM mononuclear cells obtained from male transgenic mice expressing enhanced green fluorescent protein (GFP) were used for reconstitution. Engraftment was confirmed by flow cytometry. To induce liver injury, chimeric animals received carbon tetrachloride (CCl(4)) 0.5 mL/kg intraperitoneally twice a week for 30 d (CCl(4) 30 d) and age-matched controls received saline (Saline 30 d). At the end of this period, animals were sacrificed for post mortem analysis. Liver samples were stained with hematoxylin and eosin to observe liver architectural changes and with Sirius red for collagen quantification by morphometric analysis. α-smooth muscle actin (α-SMA) was analyzed by confocal microscopy to identify GFP+ cells with myofibroblast (MF) characteristics. Liver tissue, BM and peripheral blood were collected and prepared for flow cytometric analysis using specific markers for detection of hepatic stellate cells (HSCs) and precursors from the BM.

RESULTS

Injury to the liver induced changes in the hepatic parenchymal architecture, as reflected by the presence of inflammatory infiltrate and an increase in collagen deposition (Saline 30 d = 11.10% ± 1.12% vs CCl(4) 30 d = 12.60% ± 0.73%, P = 0.0329). Confocal microscopy revealed increased reactivity against α-SMA in CCl(4) 30 d compared to Saline 30 d, but there was no co-localization with GFP+ cells, suggesting that cells from BM do not differentiate to MFs. Liver flow cytometric analysis showed a significant increase of CD45+/GFP+ cells in liver tissue (Saline 30 d = 3.2% ± 2.2% vs CCl(4) 30 d = 5.8% ± 1.3%, P = 0.0458), suggesting that this increase was due to inflammatory cell infiltration (neutrophils and monocytes). There was also a significant increase of common myeloid progenitor cells (CD117+/CD45+) in the livers of CCl(4)-treated animals (Saline 30 d = 2.16% ± 1.80% vs CCl(4) 30 d = 5.60% ± 1.30%, P = 0.0142). In addition the GFP-/CD38+/CD45- subpopulation was significantly increased in the CCl(4) 30 d group compared to the Saline 30 d group (17.5% ± 3.9% vs 9.3% ± 2.4%, P = 0.004), indicating that the increase in the activated HSC subpopulation was not of BM origin.

CONCLUSION

BM progenitor cells do not contribute to fibrosis, but there is a high recruitment of inflammatory cells that stimulates HSCs and MFs of liver origin.

Stem cell therapy in chronic liver disease

PURPOSE OF REVIEW

To provide an overview of the current status of liver regeneration therapies for liver cirrhosis and future prospects.

RECENT FINDINGS

Various clinical studies for liver disease have been reported, including hepatic administration of autologous CD34-positive cells induced by granulocyte colony-stimulating factor, portal vein administration of CD133-positive mononuclear cells, and administration of autologous bone marrow-derived mesenchymal stem cells. Effectiveness of these approaches has been shown in some patients. We have also reported improved liver fibrosis and function with infusion of autologous bone marrow cells in a basic study with mice, and on the basis of those results started autologous bone marrow cell infusion (ABMi) therapy for liver cirrhosis. The efficacy and safety of ABMi therapy has also been reported by other institutions.

SUMMARY

Results of recent clinical studies strongly suggest that liver function-improving effects can be achieved using infusion of bone marrow (stem) cells for cirrhosis. New treatment methods using less-invasive bone marrow-derived cultured cells need to be developed.

Analysis of biodistribution and engraftment into the liver of genetically modified mesenchymal stromal cells derived from adipose tissue

Presently, orthotopic liver transplant is the major therapeutic option for patients affected by primary liver diseases. This procedure is characterized by major invasive surgery, scarcity of donor organs, high costs, and lifelong immunosuppressive treatment. Transplant of hepatic precursor cells represents an attractive alternative. These cells could be used either for allogeneic transplantation or for autologous transplant after ex vivo genetic modification. We used stromal cells isolated from adipose tissue (AT-SCs) as platforms for autologous cell-mediated gene therapy. AT-SCs were transduced with lentiviral vectors expressing firefly luciferase, allowing for transplanted cell tracking by bioluminescent imaging (BLI). As a complementary approach, we followed circulating human α1-antitrypsin (hAAT) levels after infusion of AT-SCs overexpressing hAAT. Cells were transplanted into syngeneic mice after CCl(4)-induced hepatic injury. Luciferase bioluminescence signals and serum hAAT levels were measured at different time points after transplantation and demonstrate persistence of transplanted cells for up to 2 months after administration. These data, along with immunohistochemical analysis, suggest engraftment and repopulation of injured livers by transplanted AT-SCs. Moreover, by transcriptional targeting using cellular tissue-specific regulatory sequences, we confirmed that AT-SCs differentiate towards a hepatogenic-like phenotype in vitro and in vivo. Additionally, in transplanted cells reisolated from recipient animals' livers, we detected activation of the α-fetoprotein (AFP) promoter. This promoter is normally transcriptionally silenced in adult tissues but can be reactivated during liver regeneration, suggesting commitment towards hepatogenic-like differentiation of engrafted cells in vivo. Our data support AT-SC-mediated gene therapy as an innovative therapeutic option for disorders of liver metabolism.

Reduction of galectin-3 expression and liver fibrosis after cell therapy in a mouse model of cirrhosis

BACKGROUND AIMS

Cirrhosis, end-stage liver disease, is caused by different mechanisms of injury, associated with persistent inflammation. Galectin-3 is an important regulator of fibrosis that links chronic inflammation to fibrogenesis. We investigated the role of bone marrow cell (BMC) transplantation in chronic inflammation and hepatic fibrosis.

METHODS

Liver cirrhosis was induced by administration of carbon tetrachloride and ethanol to wild-type C57BL/6 or bone marrow chimeric mice. Bone marrow chimeras were generated by lethal irradiation and transplantation with BMC obtained from green fluorescent protein (GFP(+) )donors. Wild-type cirrhotic mice were transplanted with BMC without irradiation. Livers from chimeras and cirrhotic transplanted mice were obtained for evaluation of inflammation, fibrosis and regulatory factors [galectin-3, matrix metallopeptidase (MMP)-9, tissue inhibitor of metalloproteinase (TIMP)-1 and transforming growth factor (TGF)-β].

RESULTS

The development of cirrhosis was associated with increased expression of galectin-3 by F4/80(+) cells and intense migration of BMC to the liver. Furthermore, when transplanted after the establishment of cirrhosis, BMC also migrated to the liver and localized within the fibrous septa. Two months after BMC therapy, cirrhotic mice had a significant reduction in liver fibrosis and expression of type I collagen. We did not find any difference in levels of TGF-β, TIMP-1 and MMP-9 between saline and BMC groups. However, the numbers of inflammatory cells, phagocytes and galectin-3(+) cells were markedly lower in the livers of cirrhotic mice treated with BMC.

CONCLUSIONS

Our results demonstrate an important role for BMC in the regulation of liver fibrosis and that transplantation of BMC can accelerate fibrosis regression through modulatory mechanisms.

Normal hepatocyte transplantation delays the emergence of chemically induced preneoplastic nodules in rat liver

Cancer often arises in a background of chronic tissue damage. It is also increasingly appreciated that such an injured tissue microenvironment might foster the selective emergence of altered cells, leading to neoplasia. Accordingly, reversal of chronic tissue damage could represent a potential strategy to counteract neoplastic disease. In these studies, we aim to investigate whether transplantation of normal cells in the context of an injured, neoplastic-prone microenvironment might impact on the evolution of the carcinogenic process. A rat model of chemically induced hepatocarcinogenesis was used. Animals were given a single dose of diethylnitrosamine (DENA), followed by two injections of retrorsine (RS), a pyrrolizidine alkaloid that imposes a persistent block on hepatocyte cell cycle. At the end of this protocol, rats were either given no further treatment or injected, via the portal circulation, with 4 million normal hepatocytes isolated from a syngenic donor. After 3 months, rats given DENA+RS alone displayed numerous discrete nodular lesions (up to 30 per liver), ranging 1 to 3 mm in size. On the other hand, in animals receiving DENA+RS and transplantation, donor hepatocytes were able to repopulate over 50% of the host liver, as expected. Most importantly, both the number and the size of hepatocyte nodules were greatly reduced in these animals (percent nodular area was 1.8 ± 0.3, down from a control value of 8.5 ± 2.8). The above data indicate that strategies aimed at reestablishing a normal tissue microenvironment might be relevant to the management of neoplastic disease.

Derivation of high-purity definitive endoderm from human parthenogenetic stem cells using an in vitro analog of the primitive streak

Human parthenogenetic stem cells (hpSCs) are pluripotent stem cells with enormous potential as cell sources for cell-based therapies: hpSCs may have histocompatibilty advantages over human embryonic stem cells (hESCs) and derivation of hpSCs does not require viable blastocyst destruction. For translation of all pluripotent stem cell-based therapies, derivation of differentiated cell products that are not contaminated with undifferentiated cells is a major technical roadblock. We report here a novel method to derive high-purity definitive endoderm (DE) from hpSCs, based on reproducing features of the normal human embryonic microenvironment. The method mimics the developmental process of transition through a primitive streak, using a differentiation device that incorporates a three-dimensional extracellular matrix (ECM) combined with a porous membrane. Treatment of undifferentiated hpSCs above the membrane results an epithelial-to-mesenchymal transition (EMT); thus, responsive cells acquire the ability to migrate through the membrane into the ECM, where they differentiate into DE. Importantly, the resultant DE is highly purified, and is not contaminated by undifferentiated cells, as assessed by OCT4 expression using immunocytochemistry and flow cytometry. The functional properties of the DE are also preserved by the process: DE differentiated in the device can generate a highly enriched population of hepatocyte-like cells (HLCs) characterized by expression of hepatic lineage markers, indocyanine green clearance, glycogen storage, cytochrome P450 activity, and engraftment in the liver after transplantation into immunodeficient mice. The method is broadly applicable and we obtained purified DE using hESCs, as well as several hpSC lines. The novel method described here represents a significant step toward the efficient generation of high-purity cells derived from DE, including hepatocytes and pancreatic endocrine cells, for use in regenerative medicine and drug discovery, as well as a platform for studying cell fate specification and behavior during development.

[Therapeutic possibilities of stem cells in the treatment of liver diseases]

Cell therapy and the use of stem cells in the treatment of liver diseases is still in the research phase. Nevertheless, the diversity of stem cells in terms of their origin, characteristics and potential for differentiation provides a wide spectrum of possibilities for the treatment of liver diseases. The present article describes the main types of stem cells and their potential for the treatment of liver diseases, as well as the main therapeutic strategies that are currently being explored for the treatment of these diseases through cell therapy. In addition, the main preclinical and clinical studies suggesting that stem cells could become an effective therapeutic alternative in distinct liver diseases are discussed.

Labeling Stem Cells with a Near-Infrared Fluorescent Heptamethine Dye for Noninvasive Optical Tracking

Near-infrared (NIR) fluorescent agents hold great promise for noninvasive in vivo imaging. We have recently reported that a NIR fluorescent heptamethine dye, IR-780 iodide, exhibits unique optical properties for biomedical imaging. On the basis of this foregoing work, we further describe here the potential application of IR-780 iodide as a novel NIR agent for stem cell labeling and tracking. The labeling efficiency, subcellular localization, and the effects on cell viability and differentiation of IR-780 iodide were investigated. The in vivo distribution of stem cells after intravenous transplantation was traced by whole-body animal NIR imaging. Our results showed that IR-780 iodide exhibited superior labeling efficiency and biocompatibility with unique optical properties. Following whole-body NIR imaging, the pulmonary passage of stem cells was noninvasively visualized in rats after systemic transplantation of IR-780 iodide-labeled stem cells through intravenous delivery. With this NIR imaging method, we further confirmed that pretreatment with sodium nitroprusside (SNP), a vasodilator agent, significantly reduced the cell trapping in the lung and increased the cell passage through the lung capillaries. Our study suggests that IR-780 iodide may represent an effective NIR fluorophore for stem cell labeling and tracking.

Cell therapeutic options in liver diseases: cell types, medical devices and regulatory issues

Although significant progress has been made in the field of orthotopic liver transplantation, cell-based therapies seem to be a promising alternative to whole-organ transplantation. The reasons are manifold but organ shortage is the main cause for this approach. However, many problems such as the question which cell type should be used or which application site is best for transplantation have been raised. In addition, some clinicians have had success by cultivating liver cells in bioreactors for temporary life support. Besides answering the question which cell type, which injection site or even which culture form should be used for liver support recent international harmonization of legal requirements is needed to be addressed by clinicians, scientists and companies dealing with cellular therapies. We here briefly summarize the possible cell types used to partially or temporarily correct liver diseases, the most recent development of bioreactor technology and important regulatory issues.

Bone marrow cells obtained from cirrhotic rats do not improve function or reduce fibrosis in a chronic liver disease model

BACKGROUND

The objective of this study was to evaluate the therapeutic potential of bone marrow cells (BMCs) obtained from cirrhotic donors in a model of chronic liver disease.

METHODS

Chronic liver injury was induced in female Wistar rats by the association of an alcoholic diet with intraperitoneal injections of carbon tetrachloride. BMCs obtained from cirrhotic donors or placebo were injected through the portal vein. Blood analysis of alanine aminotransferase (ALT) and albumin levels, ultrasound assessment including the measurement of the portal vein diameter (PVD) and liver echogenicity, histologic evaluation with hematoxylin and eosin and Sirius red staining, and quantification of collagen deposition were performed.

RESULTS

ALT and albumin blood levels showed no significant differences between the experimental groups two months after injection. Additionally, no significant variation in PVD and liver echogenicity was found. Histological analysis also showed no significant variation in collagen deposition two months after placebo or BMC injection.

CONCLUSION

This study suggests that, even though BMC therapy using cells from healthy donors has previously shown to be effective, this is not the case when BMCs are obtained from cirrhotic animals. This result has major clinical implications when considering the use of autologous BMCs from patients with chronic liver diseases.

Transplant of Primary Human Hepatocytes Cocultured With Bone Marrow Stromal Cells to SCID Alb-uPA Mice

Hepatocytes are vulnerable to loss of function and viability in culture. Modified culture methods have been applied to maintain their functional status. Heterotypic interactions between hepatocytes and nonparenchymal neighbors in liver milieu are thought to modulate cell differentiation. Cocultivation of hepatocyte with various cell types has been applied to mimic the hepatic environment. Bone marrow stromal cells (BMSC) are plastic cell lines capable of transforming to other cell types. In this study hepatocyte coculture with BMSCs achieved long-term function of human hepatocytes in culture for 4 weeks. In vitro functional status of human hepatocytes in BMSC coculture was compared with fibroblast coculture and collagen culture by measuring albumin, human-α-1-antitrypsin (hAAT), urea secretion, CYP450 activity, and staining for intracellular albumin and glycogen. After 2 weeks in culture hepatocytes were retrieved and transplanted to severe combined immunodeficiency/albumin linked-urokinase type plasminogen activator (SCID Alb-uPA) mice and engraft-ment capacity was analyzed by human hepatic-specific function measured by hAAT levels in mouse serum, and Alu staining of mouse liver for human hepatocytes. Hepatocytes from BMSC coculture had significantly higher albumin, hAAT secretion, urea production, and cytochrome P450 (CYP450) activity than other culture groups. Staining confirmed the higher functional status in BMSC coculture. Transplantation of hepatocytes detached from BMSC cocultures showed significantly higher engraftment function than hepatocytes from other culture groups measured by hAAT levels in mouse serum. In conclusion, BMSC coculture has excellent potential for hepatocyte function preservation in vitro and in vivo after transplant. It is possible to use BMSC hepatocyte coculture as a supply of cell therapy in liver disease.

Stem cell research in cell transplantation: sources, geopolitical influence, and transplantation

If the rapidly progressing field of stem cell research reaches its full potential, successful treatments and enhanced understanding of many diseases are the likely results. However, the full potential of stem cell science will only be reached if all possible avenues can be explored and on a worldwide scale. Until 2009, the US had a highly restrictive policy on obtaining cells from human embryos and fetal tissue, a policy that pushed research toward the use of adult-derived cells. Currently, US policy is still in flux, and retrospective analysis does show the US lagging behind the rest of the world in the proportional increase in embryonic/fetal stem cell research. The majority of US studies being on either a limited number of cell lines, or on cells derived elsewhere (or funded by other sources than Federal) rather than on freshly isolated embryonic or fetal material. Neural, mesenchymal, and the mixed stem cell mononuclear fraction are the most commonly investigated types, which can generally be classified as adult-derived stem cells, although roughly half of the neural stem cells are fetal derived. Other types, such as embryonic and fat-derived stem cells, are increasing in their prominence, suggesting that new types of stem cells are still being pursued. Sixty percent of the reported stem cell studies involved transplantation, of which over three quarters were allogeneic transplants. A high proportion of the cardiovascular systems articles were on allogeneic transplants in a number of different species, including several autologous studies. A number of pharmaceutical grade stem cell products have also recently been tested and reported on. Stem cell research shows considerable promise for the treatment of a number of disorders, some of which have entered clinical trials; over the next few years it will be interesting to see how these treatments progress in the clinic.

Efficacy of periodontal stem cell transplantation in the treatment of advanced periodontitis

Periodontitis is the most common cause for tooth loss in adults and advanced types affect 10-15% of adults worldwide. The attempts to save tooth and regenerate the periodontal apparatus including cementum, periodontal ligament, and alveolar bone reach to the dental tissue-derived stem cell therapy. Although there have been several periodontitis models suggested, the apical involvement of tooth root is especially challenging to be regenerated and dental stem cell therapy for the state has never been investigated. Three kinds of dental tissue-derived adult stem cells (aDSCs) were obtained from the extracted immature molars of beagle dogs (n = 8), and ex vivo expanded periodontal ligament stem cells (PDLSCs), dental pulp stem cells (DPSCs), and periapical follicular stem cells (PAFSCs) were transplanted into the apical involvement defect. As for the lack of cementum-specific markers, anti-human cementum protein 1 (rhCEMP1) antibody was fabricated and the aDSCs and the regenerated tissues were immunostained with anti-CEMP1 antibody. Autologous PDLSCs showed the best regenerating capacity of periodontal ligament, alveolar bone, and cementum as well as peripheral nerve and blood vessel, which were evaluated by conventional and immune histology, 3D micro-CT, and clinical index. The rhCEMP1 was expressed strongest in PDLSCs and in the regenerated periodontal ligament space. We suggest here the PDLSCs as the most favorable candidate for the clinical application among the three dental stem cells and can be used for treatment of advanced periodontitis where tooth removal was indicated in the clinical cases.

Autologous hematopoietic stem cell transplantation in 48 patients with end-stage chronic liver diseases

The only presently viable treatment for end-stage liver disease is whole organ transplantation. However, there are insufficient livers available. The aim of the present study is to provide autologous bone marrow-derived stem cells as a potential therapeutic for patients with end-stage cirrhosis. This is a retrospective chart review of autologous stem cell treatment in 48 patients, 36 with chronic end-stage hepatitis C-induced liver disease and 12 with end-stage autoimmune liver disease. For all patients, granulocyte colony-stimulating factor was administered to mobilize their hematopoietic stem cells. Following leukapheresis, CD34(+) stem cells were isolated, amplified, and partially differentiated in culture, then reinjected into each subject via their hepatic artery or portal vein. Treatment was generally well tolerated with the expected moderate but transient bone pain from G-CSF in less than half of the patients. Three patients had serious treatment-related complications, and only 20.8% of these end-stage liver disease patients died during 12 months of follow up. For all patients there was a statistically significant decrease in ascites. There was clinical and biochemical improvement in a large percentage of patients who received the transplantation. In the viral group, there were marked changes in albumin (p = 0.0003), bilirubin (p = 0.04), INR (p = 0.0003), and ALT levels (p = 0.02). In the autoimmune group, values also improved significantly for albumin (p = 0.001), bilirubin (p = 0.002), INR (p = .0005), and ALT levels (p = 0.003). These results suggest that autologous CD34(+) stem cell transplantation may be safely administered and appears to offer some therapeutic benefit to patients with both viral and autoimmune-induced end-stage liver disease.