Transplanted human amniotic membrane-derived mesenchymal stem cells ameliorate carbon tetrachloride-induced liver cirrhosis in mouse

Antifibrotic Activity of Human Placental Amnion Membrane-Derived CD34+ Mesenchymal Stem/Progenitor Cell Transplantation in Mice With Thioacetamide-Induced Liver Injury

: Liver fibrosis represents the end stage of chronic liver inflammatory diseases and is defined by the abnormal accumulation of extracellular matrix in the liver. Advanced liver fibrosis results in cirrhosis, liver failure, and portal hypertension. Liver transplantation has been the most effective treatment for these diseases, but the procedure is limited by the shortage of suitable donors. Mesenchymal stromal cells (MSCs) have shown great potential in the treatment of chronic inflammatory diseases associated with fibrosis. This study aimed to evaluate the therapeutic effect of MSC-based cell transplantation as an alternative treatment for liver fibrosis. A CD34-positive subpopulation of human placental amnion membrane-derived stem/progenitor cells (CD34⁺ AMSPCs) was isolated through the depletion of CD34-negative stromal fibroblasts (CD34^- AMSFCs) facilitated by CD34 fluorescence-activated cell sorting, enriched and expanded ex vivo. These cells express pluripotency markers and demonstrate multidirectional differentiation potentials. Comparative analysis was made between CD34⁺ AMSPCs and CD34^- AMSFCs in terms of the expressions of stemness surface markers, embryonic surface antigens, and multilineage differentiation potentials. A mouse model of liver fibrosis was established by thioacetamide (TAA) administration. When injected into the spleen of TAA-injured mice, human placental amnion membrane-derived MSCs (hAM-MSCs) can engraft into the injury site, ameliorate liver fibrosis, and restore liver function, as shown by pathological and blood biochemical analysis and downregulated gene expressions associated with liver damage. CD34⁺ AMSPCs represent a more primitive subset of hAM-MSCs and could be a suitable candidate with a potentially better safety profile for cell-based therapy in treatment of liver diseases associated with fibrosis.

SIGNIFICANCE

In this study, a CD34⁺ subpopulation of stem/progenitor cells derived from neonatal placental amnion membrane, denoted as CD34⁺ AMSPCs, were identified, enriched, and characterized. These cells are highly proliferative, express mesenchymal stromal cells and pluripotent stem cell markers, and demonstrate multidirectional differentiation potentials, indicating their promising application in clinical regenerative therapies. CD34⁺ AMSPC transplantation ameliorated liver fibrosis in mice with drug-induced liver injury. These cells represent a potential therapeutic agent for treating liver diseases associated with fibrosis.

Improvement of Heart Failure by Human Amniotic Mesenchymal Stromal Cell Transplantation in Rats

Background: Recently, stem cells have been considered for the treatment of heart diseases, but no marked improvement has been recorded. This is the first study to examine the functional and histological effects of the transplantation of human amniotic mesenchymal stromal cells (hAMSCs) in rats with heart failure (HF). Methods: This study was conducted in the years 2014 and 2015. 35 male Wistar rats were randomly assigned into 5 equal experimental groups (7 rats each) as 1- Control 2- Heart Failure (HF) 3- Sham 4- Culture media 5- Stem Cell Transplantation (SCT). Heart failure was induced using 170 mg/kg/d of isoproterenol subcutaneously injection in 4 consecutive days. The failure confirmed by the rat cardiac echocardiography on day 28. In SCT group, 3×10⁶ cells in 150 µl of culture media were transplanted to the myocardium. At the end, echocardiographic and hemodynamic parameters together with histological evaluation were done. Results: Echocardiography results showed that cardiac ejection fraction in HF group increased from 58/73 ± 9% to 81/25 ± 6/05% in SCT group (p value < 0.001). Fraction shortening in HF group was increased from 27/53 ± 8/58% into 45/55 ± 6/91% in SCT group (p value < 0.001). Furthermore, hAMSCs therapy significantly improved mean diastolic blood pressure, mean arterial pressure, left ventricular systolic pressure, rate pressure product, and left ventricular end-diastolic pressure compared to those in the HF group, with the values reaching the normal levels in the control group. A marked reduction in fibrosis tissue was also found in the SCT group (p value < 0.001) compared with the animals in the HF group. Conclusion: The transplantation of hAMSCs in rats with heart failure not only decreased the level of fibrosis but also conferred significant improvement in heart performance in terms of echocardiographic and hemodynamic parameters.

Will stem cells bring hope to pathological skin scar treatment?

Pathological skin scars, such as keloids, aesthetically and psychosocially affect patients. The quest for scar reduction and the increasing recognition of patient satisfaction has led to the continued exploration of scar treatment. Stem cells are a promising source for tissue repair and regeneration. The multi-potency and secretory functions of these cells could offer possible treatments for pathological scars and have been examined in recent studies. Here, we analyze the factors that influence the formation of pathological skin scars, summarize recent research on pathological scar treatment with stem cells and elaborate on the possible mechanisms of this treatment. Additionally, other effects of stem cell treatments are also presented while evaluating potential side effects of stem cell-based pathological scar treatments. Thus, this review may provide meaningful guidance in the clinic for scar treatments with stem cells.

Multifaceted Therapeutic Benefits of Factors Derived From Dental Pulp Stem Cells for Mouse Liver Fibrosis

: Chronic liver injury from various causes often results in liver fibrosis (LF). Although the liver possesses endogenous tissue-repairing activities, these can be overcome by sustained inflammation and excessive fibrotic scar formation. Advanced LF leads to irreversible cirrhosis and subsequent liver failure and/or hepatic cancer. Here, using the mouse carbon tetrachloride (CCl₄)-induced LF model, we showed that a single intravenous administration of stem cells derived from human exfoliated deciduous teeth (SHEDs) or of SHED-derived serum-free conditioned medium (SHED-CM) resulted in fibrotic scar resolution. SHED-CM suppressed the gene expression of proinflammatory mediators, such as TNF-α, IL-1β, and iNOS, and eliminated activated hepatic stellate cells by inducing their apoptosis, but protected parenchymal hepatocytes from undergoing apoptosis. In addition, SHED-CM induced tissue-repairing macrophages that expressed high levels of the profibrinolytic factor, matrix metalloproteinase 13. Furthermore, SHED-CM suppressed the CCl₄-induced apoptosis of primary cultured hepatocytes. SHED-CM contained a high level of hepatocyte growth factor (HGF). Notably, HGF-depleted SHED-CM (dHGF-CM) did not suppress the proinflammatory response or resolve fibrotic scarring. Furthermore, SHED-CM, but not dHGF-CM, inhibited CCl₄-induced hepatocyte apoptosis. These results suggest that HGF plays a central role in the SHED-CM-mediated resolution of LF. Taken together, our findings suggest that SHED-CM provides multifaceted therapeutic benefits for the treatment of LF.

SIGNIFICANCE

This study demonstrated that a single intravenous administration of stem cells from human exfoliated deciduous teeth (SHEDs) or of the serum-free conditioned medium (CM) derived from SHEDs markedly improved mouse liver fibrosis (LF). SHED-CM suppressed chronic inflammation, eliminated activated hepatic stellate cells by inducing their apoptosis, protected hepatocytes from undergoing apoptosis, and induced differentiation of tissue-repairing macrophages expressing high levels of the profibrinolytic factor matrix metalloproteinase 13. Furthermore, hepatocyte growth factor played a central role in the SHED-CM-mediated resolution of LF. This is the first report demonstrating the multifaceted therapeutic benefits of secreted factors derived from SHEDs for LF.

Transplantation of human amniotic mesenchymal stem cells promotes neurological recovery in an intracerebral hemorrhage rat model

Human amniotic membrane mesenchymal stem cells (hAMSCs) have recently been suggested as ideal candidate stem cells for cell-based therapy. Many studies have reported the therapeutic effects of hAMSCs in numerous disease models. However, no studies have used hAMSCs to treat intracerebral hemorrhage (ICH). In the present study, we examined the therapeutic potential of hAMSCs in a rat model of ICH, and characterized the possible mechanisms of action. Adult male Wistar rats were subjected to ICH by intrastriatal injection of VII collagenase, and then were intracerebrally administered hAMSCs, fibroblasts, or phosphate-buffered saline (PBS) at 24 h after ICH. Compared with the fibroblasts and the PBS control, hAMSCs treatment significantly promoted neurological recovery, and reduced the numbers of ED1(+) activated microglia, as well as myeloperoxidase (MPO(+)), and caspase-3(+) cells in the brain injury model. In addition, hAMSCs treatment significantly increased the expression of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) in the injured brain, and promoted neurogenesis and angiogenesis, compared with the fibroblasts and the PBS control. The transplanted hAMSCs survived for at least 27 days and were negative for β-tubulin III and glial fibrillary acidic protein (GFAP). Taken together, the results suggest that hAMSCs treatment significantly promotes neurological recovery in rats after ICH. The mechanism of action could be mediated by inhibition of inflammation and apoptosis, increasing neurotrophic factor expression, and promotion of neurogenesis and angiogenesis. Thus, hAMSCs are candidate stem cells for the treatment of ICH.

Effect of Fetal Membrane-Derived Mesenchymal Stem Cell Transplantation in Rats With Acute and Chronic Pancreatitis

OBJECTIVES

Mesenchymal stem cells (MSCs) are a valuable cell source in regenerative medicine and can be isolated from fetal membranes (FMs), particularly amniotic membranes. We investigated the effect of rat FM-derived MSCs (rFM-MSCs) and human amnion-derived MSCs (hAMSCs) on the inflammatory reaction in vitro and therapeutic effects in rats with acute and chronic pancreatitis.

METHODS

Effect of rFM-MSCs or hAMSC-conditioned medium was investigated in vitro. Acute pancreatitis was induced by intraductal injection of 4% taurocholate, and rFM-MSCs were transplanted intravenously. Chronic pancreatitis was induced by intravenous injection of 5 mg/kg dibutyltin dichloride, and hAMSCs were transplanted intravenously.

RESULTS

The inflammatory reaction of macrophages induced by lipopolysaccharide and trypsin was significantly suppressed by rFM-MSC coculture. Pancreatic acinar cell injury induced by cerulein was significantly ameliorated by hAMSC-conditioned medium. Pancreatic stellate cell activation induced by tumor necrosis factor-α was significantly decreased by hAMSC-conditioned medium. Transplantation of rFM-MSCs significantly reduced the histological score and infiltration of CD68-positive macrophages in the rat pancreas. The hAMSC transplantation significantly decreased the expression of MCP-1 and attenuated the downregulation of amylase expression in the pancreas.

CONCLUSIONS

Transplantation of FM-MSCs and AMSCs suppressed the inflammatory reaction of acute and chronic pancreatitis in rats.

Mesenchymal Stem/Stromal Cells in Liver Fibrosis: Recent Findings, Old/New Caveats and Future Perspectives

Mesenchymal stem/stromal cells (MSCs) are progenitors which share plastic-adherence capacity and cell surface markers but have different properties according to their cell and tissue sources and to culture conditions applied. Many recent publications suggest that MSCs can differentiate into hepatic-like cells, which can be a consequence of either a positive selection of rare in vivo pluripotent cells or of the original plasticity of some cells contributing to MSC cultures. A possible role of MSCs in hereditary transmission of obesity and/or diabetes as well as properties of MSCs regarding immunomodulation, cell fusion and exosome release capacities are discussed according to recent literature. Limitations in methods used to track MSCs in vivo especially in the context of liver cirrhosis are addressed as well as strategies explored to enhance their migratory, survival and proliferation properties, which are known to be relevant for their future clinical use. Current knowledge regarding mechanisms involved in liver cirrhosis amelioration mediated by naïve and genetically modified MSCs as well as the effects of applying preconditioning and combined strategies to improve their therapeutic effects are evaluated. Finally, first reports of GMP guidelines and biosafety issues in MSCs applications are discussed.

Stem Cell Therapy: Current Applications and Potential for Urology

Stem cell therapy holds the potential to revolutionize the treatment of a number of chronic conditions. Stem cells ability to home in on injured sites of the body, stimulate angiogenesis, tissue regeneration, immunomodulation, anti-inflammatory, and anti-fibrotic factors have attracted their use in the treatment of many conditions. Urology has registered one of the highest experimental successes using stem cell therapy. However, the rate of clinical applications is comparatively lower. This review takes a look at our efforts so far and what needs to be done in order to maximize the clinical benefit we can derive from stem cells.

Human Amnion-Derived Mesenchymal Stem Cells Protect Human Bone Marrow Mesenchymal Stem Cells against Oxidative Stress-Mediated Dysfunction via ERK1/2 MAPK Signaling

Epidemiological evidence suggests that bone is especially sensitive to oxidative stress, causing bone loss in the elderly. Previous studies indicated that human amnion-derived mesenchymal stem cells (HAMSCs), obtained from human amniotic membranes, exerted osteoprotective effects in vivo. However, the potential of HAMSCs as seed cells against oxidative stress-mediated dysfunction is unknown. In this study, we systemically investigated their antioxidative and osteogenic effects in vitro. Here, we demonstrated that HAMSCs signicantly promoted the proliferation and osteoblastic differentiation of H2O2-induced human bone marrow mesenchymal stem cells (HBMSCs), and down-regulated the reactive oxygen species (ROS) level. Further, our results suggest that activation of the ERK1/2 MAPK signal transduction pathway is essential for both HAMSCs-mediated osteogenic and protective effects against oxidative stress-induced dysfunction in HBMSCs. U0126, a highly selective inhibitor of extracellular ERK1/2 MAPK signaling, significantly suppressed the antioxidative and osteogenic effects in HAMSCs. In conclusion, by modulating HBMSCs, HAMSCs show a strong potential in treating oxidative stress- mediated bone deficiency.

Multipotent mesenchymal stromal cells: A promising strategy to manage alcoholic liver disease

Chronic alcohol consumption is a major cause of liver disease. The term alcoholic liver disease (ALD) refers to a spectrum of mild to severe disorders including steatosis, steatohepatitis, cirrhosis, and hepatocellular carcinoma. With limited therapeutic options, stem cell therapy offers significant potential for these patients. In this article, we review the pathophysiologic features of ALD and the therapeutic mechanisms of multipotent mesenchymal stromal cells, also referred to as mesenchymal stem cells (MSCs), based on their potential to differentiate into hepatocytes, their immunomodulatory properties, their potential to promote residual hepatocyte regeneration, and their capacity to inhibit hepatic stellate cells. The perfect match between ALD pathogenesis and MSC therapeutic mechanisms, together with encouraging, available preclinical data, allow us to support the notion that MSC transplantation is a promising therapeutic strategy to manage ALD onset and progression.

Human Amnion-Derived Mesenchymal Stem Cell Transplantation Ameliorates Dextran Sulfate Sodium-Induced Severe Colitis in Rats

Mesenchymal stem cells (MSCs) are a valuable cell source in regenerative medicine. Recently, several studies have shown that MSCs can be easily isolated from human amnion. In this study, we investigated the therapeutic effect of human amnion-derived MSCs (AMSCs) in rats with severe colitis. Colitis was induced by the administration of 8% dextran sulfate sodium (DSS) from day 0 to day 5, and AMSCs (1 × 106 cells) were transplanted intravenously on day 1. Rats were sacrificed on day 5, and the colon length and histological colitis score were evaluated. The extent of inflammation was evaluated using quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and immunohistochemistry. The effect of AMSCs on the inflammatory signals was investigated in vitro. AMSC transplantation significantly ameliorated the disease activity index score, weight loss, colon shortening, and the histological colitis score. mRNA expression levels of proinflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and migration inhibitory factor (MIF) were significantly decreased in the rectums of AMSC-treated rats. In addition, the infiltration of monocytes/macrophages was significantly decreased in AMSC-treated rats. In vitro experiments demonstrated that activation of proinflammatory signals induced by TNF-α or lipopolysaccharide (LPS) in immortalized murine macrophage cells (RAW264.7) was significantly attenuated by coculturing with AMSCs or by culturing with a conditioned medium obtained from AMSCs. Although the phosphorylation of IκB induced by TNF-α or LPS was not inhibited by the conditioned medium, nuclear translocation of NF-κB was significantly inhibited by the conditioned medium. Taken together, AMSC transplantation provided significant improvement in rats with severe colitis, possibly through the inhibition of monocyte/macrophage activity and through inhibition of NF-κB activation. AMSCs could be considered as a new cell source for the treatment of severe colitis.

Human Amnion-Derived Mesenchymal Stem Cells Promote Osteogenic Differentiation in Human Bone Marrow Mesenchymal Stem Cells by Influencing the ERK1/2 Signaling Pathway

Human amnion-derived mesenchymal stem cells (HAMSCs) are considered to be an important resource in the field of tissue engineering because of their anti-inflammatory properties and fewer ethical issues associated with their use compared with other sources of stem cells. HAMSCs can be obtained from human amniotic membranes, a readily available and abundant tissue. However, the potential of HAMSCs as seed cells for treating bone deficiency is unknown. In this study, HAMSCs were used to promote proliferation and osteoblastic differentiation in human bone marrow mesenchymal stem cells (HBMSCs) in a Transwell coculture system. Proliferation levels were investigated by flow cytometry and immunofluorescence staining of 5-ethynyl-2′-deoxyuridine (EdU). Osteoblastic differentiation and mineralization were evaluated in chromogenic alkaline phosphatase (ALP) activity substrate assays, Alizarin red S staining, and RT-PCR analysis of early HBMSCs osteogenic marker expression. We demonstrated that HAMSCs stimulated increased alkaline phosphatase (ALP) activity, mRNA expression of osteogenic marker genes, and mineralized matrix deposition. Moreover, the effect of HAMSCs was significantly inhibited by U0126, a highly selective inhibitor of extracellular signaling-regulated kinase 1/2 (ERK1/2) signaling. We demonstrate that HAMSCs promote osteogenic differentiation in HBMSCs by influencing the ERK1/2 signaling pathway. These observations confirm the potential of HAMSCs as a seed cell for the treatment of bone deficiency.

Selective cytotoxicity and cell death induced by human amniotic membrane in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) has a worldwide high incidence and mortality. For this reason, it is essential to invest in new therapies for this type of cancer. Our team already proved that human amniotic membrane (hAM) is able to inhibit the metabolic activity of several human cancer cell lines, including HCC cell lines. Taking into account the previously performed work, this experimental study aimed to investigate the pathways by which hAM protein extracts (hAMPEs) act on HCC. Our results showed that hAMPE reduce the metabolic activity, protein content and DNA content in a dose- and time-dependent manner in all HCC cell lines. This therapy presents selective cytotoxicity, since it was not able to inhibit a non-tumorigenic human cell line. In addition, hAMPE induced cell morphology alterations in all HCC cell lines, but death type is cell line dependent, as proved by in vitro and in vivo studies. In conclusion, hAMPE have a promising role in HCC therapy, since it is capable of inducing HCC cytotoxicity and cell death.

Anti-aging Effect of Transplanted Amniotic Membrane Mesenchymal Stem Cells in a Premature Aging Model of Bmi-1 Deficiency

To determine whether transplanted amniotic membrane mesenchymal stem cells (AMSCs) ameliorated the premature senescent phenotype of Bmi-1-deficient mice, postnatal 2-day-old Bmi-1(-/-) mice were injected intraperitoneally with the second-passage AMSCs from amniotic membranes of β-galactosidase (β-gal) transgenic mice or wild-type (WT) mice labeled with DiI. Three reinjections were given, once every seven days. Phenotypes of 5-week-old β-gal(+) AMSC-transplanted or 6-week-old DiI(+) AMSC-transplanted Bmi-1(-/-) mice were compared with vehicle-transplanted Bmi-1(-/-) and WT mice. Vehicle-transplanted Bmi-1(-/-) mice displayed growth retardation and premature aging with decreased cell proliferation and increased cell apoptosis; a decreased ratio and dysmaturity of lymphocytic series; premature osteoporosis with reduced osteogenesis and increased adipogenesis; redox imbalance and DNA damage in multiple organs. Transplanted AMSCs carried Bmi-1 migrated into multiple organs, proliferated and differentiated into multiple tissue cells, promoted growth and delayed senescence in Bmi-1(-/-) transplant recipients. The dysmaturity of lymphocytic series were ameliorated, premature osteoporosis were rescued by promoting osteogenesis and inhibiting adipogenesis, the oxidative stress and DNA damage in multiple organs were inhibited by the AMSC transplantation in Bmi-1(-/-) mice. These findings indicate that AMSC transplantation ameliorated the premature senescent phenotype of Bmi-1-deficient mice and could be a novel therapy to delay aging and prevent aging-associated degenerative diseases.

Mesenchymal stem cell therapy for liver fibrosis

Currently, the most effective treatment for end-stage liver fibrosis is liver transplantation; however, transplantation is limited by a shortage of donor organs, surgical complications, immunological rejection, and high medical costs. Recently, mesenchymal stem cell (MSC) therapy has been suggested as an effective alternate approach for the treatment of hepatic diseases. MSCs have the potential to differentiate into hepatocytes, and therapeutic value exists in their immune-modulatory properties and secretion of trophic factors, such as growth factors and cytokines. In addition, MSCs can suppress inflammatory responses, reduce hepatocyte apoptosis, increase hepatocyte regeneration, regress liver fibrosis and enhance liver functionality. Despite these advantages, issues remain; MSCs also have fibrogenic potential and the capacity to promote tumor cell growth and oncogenicity. This paper summarizes the properties of MSCs for regenerative medicine and their therapeutic mechanisms and clinical application in the treatment of liver fibrosis. We also present several outstanding risks, including their fibrogenic potential and their capacity to promote pre-existing tumor cell growth and oncogenicity.

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

MSCs have become a popular target for developing end-stage liver therapies. In this study, two models of bone marrow chimeric mice were used to construct the liver failure models. Then it was found that MSCs can transdifferentiate into hepatocyte-like cells and these hepatocyte-like cells can significantly express albumin. Furthermore it was also found that MSCs can fuse with the hepatocytes and these cells had the proliferation activity. However, the percentage of transdifferentiation was significantly higher than fusion. So it was considered that MSCs which transdifferentiated into hepatocyte-likes cells played important roles for repairing the injuring liver function.

Repeated versus single transplantation of mesenchymal stem cells in carbon tetrachloride-induced liver injury in mice

Despite its numerous limitations, liver transplants are the only definite cure for end-stage liver disease. Various stem cell populations may contribute to liver regeneration, of which there is accumulating evidence of the contribution of mesenchymal stem cells (MSCs). This study examines the hypothesis that repeated infusions of human bone marrow-derived MSCs (hBMMSCs)can improve liver injury in an experimental model. MSCs were intravenously transplanted into immunosuppressed mice with carbon tetrachloride (CCl(4))-induced liver fibrosis. Transplanting 3x10(6) MSCs in three divided doses improved survival,liver fibrosis and necrosis compared with injection of the same number of MSCs in a single dose. This was accompanied by increased influence on the expression of the fibrogenic/fibrolytic related genes Col1a1, Timp1 and Mmp13 in the repeated transplant group. Repeat administration of MSCs was three times more effective in homing of PKH-tagged transplanted cells 3 weeks post-transplant compared with the single transplant group. The benefits of repeated transplants may be of considerable significance in clinical trials on liver failure.

Human Amnion-Derived Mesenchymal Stem Cell Transplantation Ameliorates Liver Fibrosis in Rats

Mesenchymal stem cells (MSCs) are a valuable cell source in regenerative medicine. Recently, several studies have shown that MSCs can be easily isolated from human amnion. In this study, we investigated the therapeutic effect of transplantation of human amnion-derived MSCs (hAMSCs) in rats with liver fibrosis.

METHODS

Liver fibrosis was induced by an intraperitoneal injection of 2 mL/kg of 50% carbon tetrachloride twice a week for 6 weeks. At 3 weeks, hAMSCs (1 × 10(6) cells) were transplanted intravenously. Rats were sacrificed at 7 weeks, and histological analyses and quantitative reverse-transcription polymerase chain reaction were performed. In vitro experiments were conducted to investigate the effect of hAMSCs on the activation of Kupffer cells.

RESULTS

Transplantation of hAMSCs significantly reduced the fibrotic area, deposition of type-I collagen, the number of α-smooth muscle actin-positive hepatic stellate cells, and CD68-positive Kupffer cells in the livers. messenger RNA expression of α-smooth muscle actin and tissue inhibitor of metalloproteinase-1 was significantly decreased and the expression of matrix metalloproteinase-9 and hepatocyte growth factor was significantly increased in the liver of hAMSC-treated rats. Transplantation of hAMSCs at 3 weeks plus 5 weeks did not have an additive effect. In vitro experiments demonstrated that Kupffer cell activation induced by lipopolysaccharide was significantly decreased by culturing with conditioned medium obtained from hAMSCs.

CONCLUSIONS

Transplantation of hAMSCs provided significant improvement in a rat model of liver fibrosis, possibly through the inhibition of Kupffer cell and hepatic stellate cell activation. hAMSCs may be a potential new treatment for liver fibrosis.

A Comparison of Culture Characteristics between Human Amniotic Mesenchymal Stem Cells and Dental Stem Cells

In the past decade, the field of stem cell biology is of major interest among researchers due to its broad therapeutic potential. Stem cells are a class of undifferentiated cells that are able to differentiate into specialised cell types. Stem cells can be classified into two main types: adult stem cells (adult tissues) and embryonic stem cells (embryos formed during the blastocyst phase of embryological development). This review will discuss two types of adult mesenchymal stem cells, dental stem cells and amniotic stem cells, with respect to their differentiation lineages, passage numbers and animal model studies. Amniotic stem cells have a greater number of differentiation lineages than dental stem cells. On the contrary, dental stem cells showed the highest number of passages compared to amniotic stem cells. For tissue regeneration based on animal studies, amniotic stem cells showed the shortest time to regenerate in comparison with dental stem cells.

Neuroprotective effects of GDNF-expressing human amniotic fluid cells

Brain injury continues to be one of the leading causes of disability worldwide. Despite decades of research, there is currently no pharmacologically effective treatment for preventing neuronal loss and repairing the brain. As a result, novel therapeutic approaches, such as cell-based therapies, are being actively pursued to repair tissue damage and restore neurological function after injury. In this study, we examined the neuroprotective potential of amniotic fluid (AF) single cell clones, engineered to secrete glial cell derived neurotrophic factor (AF-GDNF), both in vitro and in a surgically induced model of brain injury. Our results show that pre-treatment with GDNF significantly increases cell survival in cultures of AF cells or cortical neurons exposed to hydrogen peroxide. Since improving the efficacy of cell transplantation depends on enhanced graft cell survival, we investigated whether AF-GDNF cells seeded on polyglycolic acid (PGA) scaffolds could enhance graft survival following implantation into the lesion cavity. Encouragingly, the AF-GDNF cells survived longer than control AF cells in serum-free conditions and continued to secrete GDNF both in vitro and following implantation into the injured motor cortex. AF-GDNF implantation in the acute period following injury was sufficient to activate the MAPK/ERK signaling pathway in host neural cells in the peri-lesion area, potentially boosting endogenous neuroprotective pathways. These results were complemented with promising trends in beam walk tasks in AF-GDNF/PGA animals during the 7 day timeframe. Further investigation is required to determine whether significant behavioural improvement can be achieved at a longer timeframe.

Human amnion mesenchymal stem cells promote proliferation and osteogenic differentiation in human bone marrow mesenchymal stem cells

Human amnion mesenchymal stem cells (HAMSCs) can be obtained from human amniotic membrane, a highly abundant and readily available tissue. HAMSC sources present fewer ethical issues, have low immunogenicity, anti-inflammatory properties, considerable advantageous characteristics, and are considered an attractive potential treatment material in the field of regenerative medicine. We used a co-culture system to determine whether HAMSCs could promote osteogenesis in human bone marrow mesenchymal stem cells (HBMSCs). We isolated HAMSCs from discarded amnion samples and collected them using pancreatin/collagenase digestion. We cultured HAMSCs and HBMSCSs in basal medium. Activity of alkaline phosphatase (ALP), an early osteogenesis marker, was increased in the co-culture system compared to the control single cultures, which we also confirmed by ALP staining. We used immunofluorescence testing to investigate the effects of co-culturing with HAMSCs on HBMSC proliferation, which revealed that the co-culturing enhanced EdU expression in HBMSCs. Western blotting and quantitative real-time PCR indicated that co-culturing promoted osteogenesis in HBMSCs. Furthermore, Alizarin red S staining revealed that extracellular matrix calcium levels in mineralized nodule formation produced by the co-cultures were higher than that in the controls. Using the same co-culture system, we further observed the effects of HAMSCs on osteogenic differentiation in primary osteoblasts by Western blotting, which better addressed the mechanism for HAMSCs in bone regeneration. The results showed HAMSCs are osteogenic and not only play a role in promoting HBMSC proliferation and osteogenic differentiation but also in osteoblasts, laying the foundation for new regenerative medicine methods.

Bone marrow stromal cells as immunomodulators. A primer for dermatologists

Bone marrow stromal cells (BMSCs, also known as mesenchymal stem cells or MSCs) represent a unique cell population in the bone marrow with a long-known function to support hematopoiesis and replace skeletal tissues. The recent discovery that BMSCs also possess potent immunoregulatory features attracted a great deal of attention from stem cell biologists, immunologists and clinicians of different specialties worldwide. Initial clinical experience along with several animal models suggested that intravenously delivered BMSCs are able to regulate a wide variety of host immune cells and act in a way that is beneficial for the recipient in a variety of diseases. The role of the present review is to give a short introduction to the biology of BMSCs and to summarize our current understanding of how BMSCs modulate the immune system with special emphasis on available clinical data. Considering the audience of this journal we will also attempt to guide dermatologists in choosing the right skin conditions where BMSCs might be considered as a therapeutic alternative.

Management of fibrosis: the mesenchymal stromal cells breakthrough

Fibrosis is the endpoint of many chronic inflammatory diseases and is defined by an abnormal accumulation of extracellular matrix components. Despite its slow progression, it leads to organ malfunction. Fibrosis can affect almost any tissue. Due to its high frequency, in particular in the heart, lungs, liver, and kidneys, many studies have been conducted to find satisfactory treatments. Despite these efforts, current fibrosis management therapies either are insufficiently effective or induce severe adverse effects. In the light of these facts, innovative experimental therapies are being investigated. Among these, cell therapy is regarded as one of the best candidates. In particular, mesenchymal stromal cells (MSCs) have great potential in the treatment of inflammatory diseases. The value of their immunomodulatory effects and their ability to act on profibrotic factors such as oxidative stress, hypoxia, and the transforming growth factor-β1 pathway has already been highlighted in preclinical and clinical studies. Furthermore, their propensity to act depending on the microenvironment surrounding them enhances their curative properties. In this paper, we review a large range of studies addressing the use of MSCs in the treatment of fibrotic diseases. The results reported here suggest that MSCs have antifibrotic potential for several organs.

Human placenta-derived mesenchymal stem cells promote hepatic regeneration in CCl4 -injured rat liver model via increased autophagic mechanism

Mesenchymal stem cells (MSCs) have great potential for cell therapy in regenerative medicine, including liver disease. Even though ongoing research is dedicated to the goal of bringing MSCs to clinical applications, further understanding of the complex underlying mechanisms is required. Autophagy, a type II programmed cell death, controls cellular recycling through the lysosomal system in damaged cells or tissues. However, it is still unknown whether MSCs can trigger autophagy to enhance regeneration and/or to provide a therapeutic effect as cellular survival promoters. We therefore investigated autophagy's activation in carbon tetrachloride (CCl4 )-injured rat liver following transplantation with chorionic plate-derived MSCs (CP-MSCs) isolated from placenta. The expression markers for apoptosis, autophagy, cell survival, and liver regeneration were analyzed. Whereas caspase 3/7 activities were reduced (p < .05), the expression levels of hypoxia-inducible factor-1α (HIF-1α) and factors for autophagy, survival, and regeneration were significantly increased by CP-MSCs transplantation. Decreased necrotic cells (p < .05) and increased autophagic signals (p < .005) were observed in CCl4 -treated primary rat hepatocytes during in vitro coculture with CP-MSCs. Furthermore, the upregulation of HIF-1α promotes the regeneration of damaged hepatic cells through an autophagic mechanism marked by increased levels of light chain 3 II (LC 3II). These results suggest that the administration of CP-MSCs promotes repair by systemically concomitant mechanisms involving HIF-1α and autophagy. These findings provide further understanding of the mechanisms involved in these processes and will help develop new cell-based therapeutic strategies for regenerative medicine in liver disease.

The subtype CD200-positive, chorionic mesenchymal stem cells from the placenta promote regeneration of human hepatocytes

Human placental mesenchymal stem cells (hPMSCs), for the treatment of fulminant hepatic failure, have been widely studied. Only a few studies have investigated the effect of the subtype CD200(+)hPMSCs on regeneration of human hepatocytes. CD200(+)hPMSCs can down-regulate activity of several immunocytes and suppress TNF-α secretion from macrophages via the CD200-CD200R axis. We have investigated the influence of CD200-positive human placenta chorionic mesenchymal stem cells (CD200(+)hPCMSCs) on metabolism, proliferation and apoptosis of human hepatocytes in vitro. CD200(+)hPCMSCs promote urea synthesis, albumin secretion and hepatocytes proliferation at co-culture ratios of 1:1 and 3:1. Additionally, CD200(+)hPCMSCs inhibit hepatocyte apoptosis via up-regulation of an anti-apoptotic protein, Bcl-xL. Thus, CD200(+)hPCMSCs can provide supportive benefit for the regeneration of human hepatocytes and also have immunosuppressive properties. Therefore, CD200(+)hPCMSCs may be an ideal candidate for stem cell-based therapy in hepatic failure.

Therapeutic potential of placenta-derived stem cells for liver diseases: current status and perspectives

Over the last decade, there has been a growing interest in the human placenta as a unique source of stem cells. The placenta is a fetal organ that is normally discarded following delivery. Therefore, it is readily available as a source of cells without the ethical concerns normally associated with embryonic stem cells. These cells also carry less risk for age- and environmental-related DNA damage. In addition to these practical advantages of placenta-derived cells, amniotic epithelial cells possess unique stem cell-like biological characteristics. In contrast to other parts of the placenta, cells from the amniotic epithelium are derived from pluripotent epiblasts and possess the ability to differentiate into all three germ layers. From a translational perspective, amnion-derived stem cells are very attractive candidates for clinical application. These cells are genetically stable and do not demonstrate tumorigenicity upon transplantation, and may be endowed with immunomodulatory and/or anti-inflammatory properties. These unique characteristics have made amniotic epithelial cells attractive for use as stem cell-based therapies for liver disease. Human and rodent amniotic epithelial cells have already demonstrated their therapeutic efficacy in multiple animal models. Although the detailed mechanism by which the transplanted cells generate a therapeutic effect is not yet totally understood, these dramatic results have generated significant interest for consideration of these amnion-derived stem cells for clinical applications. This review covers recent findings of the therapeutic potential of amnion-derived stem cells for liver diseases, and provides perspectives for future developments.

How important is differentiation in the therapeutic effect of mesenchymal stromal cells in liver disease?

BACKGROUND AIMS

The protocols for differentiation of hepatocyte-like cells (HLCs) from mesenchymal stromal cells (MSCs) have been well established. Previous data have shown that MSCs and their derived HLCs were able to engraft injured liver and alleviate injuries induced by carbon tetrachloride. The goal of the current study was to determine the differences of MSCs and their derived HLCs in terms of therapeutic functions in liver diseases.

METHODS

After hepatic differentiation of umbilical cord-derived MSCs in vitro, we detected both MSC and HLC expressions of adhesion molecules and chemokine receptor CXCR4 by flow cytometry; immunosuppressive potential and hepatocyte growth factor expression were determined by means of enzyme-linked immunosorbent assay. We compared the therapeutic effect for fulminant hepatic failure in a mouse model.

RESULTS

MSC-derived-HLCs expressed lower levels of hepatocyte growth factor, accompanied by impaired immunosuppression in comparison with MSCs. Furthermore, undifferentiated MSCs showed rescuing potentials superior to those in HLCs for the treatment of fulminant hepatic failure.

CONCLUSIONS

After differentiation, HLCs lost several major properties in comparison with undifferentiated MSCs, which are beneficial for their application in liver diseases. Undifferentiated MSCs may be more appropriate than are HLCs for the treatment of liver diseases.

Amnion-derived multipotent progenitor cells support allograft tolerance induction

Donor-specific immunological tolerance using high doses of bone marrow cells (BMCs) has been demonstrated in mixed chimerism-based tolerance induction protocols; however, the development of graft versus host disease remains a risk. Here, we demonstrate that the co-infusion of limited numbers of donor unfractionated BMCs with human amnion-derived multipotent progenitor cells (AMPs) 7 days post-allograft transplantation facilitates macrochimerism induction and graft tolerance in a mouse skin transplantation model. AMPs + BMCs co-infusion with minimal conditioning led to stable, mixed, multilineage lymphoid and myeloid macrochimerism, deletion of donor-reactive T cells, expansion of CD4(+)CD25(+)Foxp3(+) regulatory T cells (T(regs)) and long-term allograft survival (>300 days). Based on these findings, we speculate that AMPs maybe a pro-tolerogenic cellular therapeutic that could have clinical efficacy for both solid organ and hematopoietic stem cell transplant applications.

Developing a New Two-Step Protocol to Generate Functional Hepatocytes from Wharton's Jelly-Derived Mesenchymal Stem Cells under Hypoxic Condition

The shortage of donor livers and hepatocytes is a major limitation of liver transplantation. Thus, generation of hepatocyte-like cells may provide alternative choice for therapeutic applications. In this study, we developed a new method to establish hepatocytes from Wharton's jelly-derived mesenchymal stem cells (WJ-MSCs) cell lines named WJMSCs-SUT1 and WJMSCs-SUT2 under hypoxic condition. This new method could rapidly drive both WJ-MSCs cell lines into hepatic lineage within 18 days. The achievement of hepatogenic differentiation was confirmed by the characterization of both phenotypes and functions. More than 80% MSCs-derived hepatocyte-like cells (MSCDHCs) achieved functional hepatocytes including hepatic marker expressions both at gene and protein levels, glycogen storage, low-density lipoprotein uptake, urea production, and albumin secretion. This study highlights the establishment of new hepatogenic induction protocol under hypoxic condition in order to mimic hypoxic microenvironment in typical cell physiology. In conclusion, we present a simple, high-efficiency, and time saving protocol for the generation of functional hepatocyte-like cells from WJ-MSCs in hypoxic condition. The achievement of this method may overcome the limitation of donor hepatocytes and provides a new avenue for therapeutic value in cell-based therapy for life-threatening liver diseases, regenerative medicine, toxicity testing for pharmacological drug screening, and other medical related applications.

Allogeneic bone marrow-derived mesenchymal stem cells attenuate hepatic ischemia-reperfusion injury by suppressing oxidative stress and inhibiting apoptosis in rats

Bone marrow-derived mesenchymal stem cells (BM-MSCs) have been shown to attenuate ischemia reperfusion (IR) injury in the heart, brain and kidney. However, their exact roles in the liver remain to be defined. Our objective was to investigate the potential effects of BM-MSCs on a hepatic IR rat model during the first 24 h after reperfusion, a crucial period for hepatic IR damage formation. A rat model of normothermic partial hepatic ischemia was obtained by vascular clamping for 60 min. BM-MSCs were transplanted via portal vein injection. Injury severity, oxidative stress response and apoptosis of liver cells were assessed at 2, 6, 12 and 24 h after reperfusion and cell transplantation was evaluated. At 12 and 24 h after reperfusion, rats transplanted with BM-MSCs had significantly lower serum levels of alanine aminotransferase (ALT) and serum aspartate aminotransferase (AST), fewer damaged liver tissues, higher superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities and lower malondialdehyde (MDA) levels compared to rats in the sham transplantation group. At 24 h after reperfusion, IR rats transplanted with BM-MSCs had significantly fewer apoptotic hepatocytes, higher levels of B-cell lymphoma 2 (Bcl-2) protein, and lower levels of Bcl-2-associated X (Bax) and caspase-3 (Casp3) proteins compared to sham transplantation rats. In conclusion, BM-MSCs transplanted via the portal vein partially prevent hepatic IR injury by suppressing oxidative stress and inhibiting apoptosis during the first 24 h after reperfusion.

Placental stem cell correction of murine intermediate maple syrup urine disease

There is improved survival and partial metabolic correction of a mouse intermediate maple syrup urine disease (iMSUD) model after allogenic hepatocyte transplantation, confirming that a small number of enzyme-proficient liver-engrafted cells can improve phenotype. However, clinical shortages of suitable livers for hepatocyte isolation indicate a need for alternative cell sources. Human amnion epithelial cells (hAECs) share stem cell characteristics without the latter's safety and ethical concerns and differentiate to hepatocyte-like cells. Eight direct hepatic hAEC transplantations were performed in iMSUD mice over the first 35 days beginning at birth; animals were provided a normal protein diet and sacrificed at 35 and 100 days. Treatment at the neonatal stage is clinically relevant for MSUD and may offer a donor cell engraftment advantage. Survival was significantly extended and body weight was normalized in iMSUD mice receiving hAEC transplantations compared with untreated iMSUD mice, which were severely cachectic and died ≤28 days after birth. Branched chain α-keto acid dehydrogenase enzyme activity was significantly increased in transplanted livers. The branched chain amino acids leucine, isoleucine, valine, and alloisoleucine were significantly improved in serum and brain, as were other large neutral amino acids.

CONCLUSION

Placental-derived stem cell transplantation lengthened survival and corrected many amino acid imbalances in a mouse model of iMSUD. This highlights the potential for their use as a viable alternative clinical therapy for MSUD and other liver-based metabolic diseases.

Advances in cell sources of hepatocytes for bioartificial liver

BACKGROUND

Orthotopic liver transplantation (OLT) is the most effective therapy for liver failure. However, OLT is severely limited by the shortage of liver donors. Bioartificial liver (BAL) shows great potential as an alternative therapy for liver failure. In recent years, progress has been made in BAL regarding genetically engineered cell lines, immortalized human hepatocytes, methods for preserving the phenotype of primary human hepatocytes, and other functional hepatocytes derived from stem cells.

DATA SOURCES

A systematic search of PubMed and ISI Web of Science was performed to identify relevant studies in English language literature using the key words such as liver failure, bioartificial liver, hepatocyte, stem cells, differentiation, and immortalization. More than 200 articles related to the cell sources of hepatocyte in BAL were systematically reviewed.

RESULTS

Methods for preserving the phenotype of primary human hepatocytes have been successfully developed. Many genetically engineered cell lines and immortalized human hepatocytes have also been established. Among these cell lines, the incorporation of BAL with GS-HepG2 cells or alginate-encapsulated HepG2 cells could prolong the survival time and improve pathophysiological parameters in an animal model of liver failure. The cBAL111 cells were evaluated using the AMC-BAL bioreactor, which could eliminate ammonia and lidocaine, and produce albumin. Importantly, BAL loading with HepLi-4 cells could significantly improve the blood biochemical parameters, and prolong the survival time in pigs with liver failure. Other functional hepatocytes differentiated from stem cells, such as human liver progenitor cells, have been successfully achieved.

CONCLUSIONS

Aside from genetically modified liver cell lines and immortalized human hepatocytes, other functional hepatocytes derived from stem cells show great potential as cell sources for BAL. BAL with safe and effective liver cells may be achieved for clinical liver failure in the near future.

Applications of amniotic membrane and fluid in stem cell biology and regenerative medicine

The amniotic membrane (AM) and amniotic fluid (AF) have a long history of use in surgical and prenatal diagnostic applications, respectively. In addition, the discovery of cell populations in AM and AF which are widely accessible, nontumorigenic and capable of differentiating into a variety of cell types has stimulated a flurry of research aimed at characterizing the cells and evaluating their potential utility in regenerative medicine. While a major focus of research has been the use of amniotic membrane and fluid in tissue engineering and cell replacement, AM- and AF-derived cells may also have capabilities in protecting and stimulating the repair of injured tissues via paracrine actions, and acting as vectors for biodelivery of exogenous factors to treat injury and diseases. Much progress has been made since the discovery of AM and AF cells with stem cell characteristics nearly a decade ago, but there remain a number of problematic issues stemming from the inherent heterogeneity of these cells as well as inconsistencies in isolation and culturing methods which must be addressed to advance the field towards the development of cell-based therapies. Here, we provide an overview of the recent progress and future perspectives in the use of AM- and AF-derived cells for therapeutic applications.

Therapeutic potential of transplanted placental mesenchymal stem cells in treating Chinese miniature pigs with acute liver failure

BACKGROUND

Stem cell-based therapy to treat liver diseases is a focus of current research worldwide. So far, most such studies depend on rodent hepatic failure models. The purpose of this study was to isolate mesenchymal stem cells from human placenta (hPMSCs) and determine their therapeutic potential for treating Chinese experimental miniature pigs with acute liver failure (ALF).

METHODS

hPMSCs were isolated and analyzed for their purity and differentiation potential before being employed as the donor cells for transplantation. ALF models of Chinese experimental miniature pigs were established and divided into four groups: no cell transplantation; hPMSCs transplantation via the jugular vein; X-ray-treated hPMSCs transplantation via the portal vein; and hPMSCs transplantation via the portal vein. The restoration of biological functions of the livers receiving transplantation was assessed via a variety of approaches such as mortality rate determination, serum biochemical analysis, and histological, immunohistochemical, and genetic analysis.

RESULTS

hPMSCs expressed high levels of CD29, CD73, CD13, and CD90, had adipogenic, osteogenic, and hepatic differentiation potential. They improved liver functions in vivo after transplantation into the D-galactosamine-injured pig livers as evidenced by the fact that ALT, AST, ALP, CHE, TBIL, and TBA concentrations returned to normal levels in recipient ALF pigs. Meanwhile, histological data revealed that transplantation of hPMSCs via the portal vein reduced liver inflammation, decreased hepatic denaturation and necrosis, and promoted liver regeneration. These ameliorations were not found in the other three groups. The result of 7-day survival rates suggested that hPMSCs transplantation via the portal vein was able to significantly prolong the survival of ALF pigs compared with the other three groups. Histochemistry and RT-PCR results confirmed the presence of transplanted human cells in recipient pig livers (Groups III, IV).

CONCLUSIONS

Our data revealed that hPMSCs could not only differentiate into hepatocyte-like cells in vitro and in vivo, but could also prolong the survival time of ALF pigs. Regarding the transplantation pathways, the left branch of the portal vein inside the liver was superior to the jugular vein pathway. Thus, hPMSCs transplantation through the portal vein by B-ultrasonography may represent a superior approach for treating liver diseases.

Potential antitumor therapeutic strategies of human amniotic membrane and amniotic fluid-derived stem cells

As stem cells are capable of self-renewal and can generate differentiated progenies for organ development, they are considered as potential source for regenerative medicine and tissue replacement after injury or disease. Along with this capacity, stem cells have the therapeutic potential for treating human diseases including cancers. According to the origins, stem cells are broadly classified into two types: embryonic stem cells (ESCs) and adult stem cells. In terms of differentiation potential, ESCs are pluripotent and adult stem cells are multipotent. Amnion, which is a membranous sac that contains the fetus and amniotic fluid and functions in protecting the developing embryo during gestation, is another stem cell source. Amnion-derived stem cells are classified as human amniotic membrane-derived epithelial stem cells, human amniotic membrane-derived mesenchymal stem cells and human amniotic fluid-derived stem cells. They are in an intermediate stage between pluripotent ESCs and lineage-restricted adult stem cells, non-tumorigenic, and contribute to low immunogenicity and anti-inflammation. Furthermore, they are easily available and do not cause any controversial issues in their recovery and applications. Not only are amnion-derived stem cells applicable in regenerative medicine, they have anticancer capacity. In non-engineered stem cells transplantation strategies, amnion-derived stem cells effectively target the tumor and suppressed the tumor growth by expressing cytotoxic cytokines. Additionally, they also have a potential as novel delivery vehicles transferring therapeutic genes to the cancer formation sites in gene-directed enzyme/prodrug combination therapy. Owing to their own advantageous properties, amnion-derived stem cells are emerging as a new candidate in anticancer therapy.

Inhibition of kupffer cell activity improves transplantation of human adipose-derived stem cells and liver functions

Numerous approaches to cell transplantation of the hepatic or the extrahepatic origin into liver tissue have been developed; however, the efficiency of cell transplantation remains low and liver functions are not well corrected. The liver is a highly immunoreactive organ that contains many resident macrophages known as Kupffer cells. Here, we show that the inhibition of Kupffer cell activity improves stem cell transplantation into liver tissue and corrects some of the liver functions under conditions of liver injury. We found that, when Kupffer cells were inhibited by glycine, numerous adipose-derived stem cells (ASCs) were successfully transplanted into livers, and these transplanted cells showed hepatoprotective effects, including decrease of liver injury factors, increase of liver regeneration, and albumin production. On the contrary, injected ASCs without glycine recruited numerous Kupffer cells, not lymphocytes, and showed low transplantation efficiency. Intriguingly, successfully transplanted ASCs in liver tissue modulated Kupffer cell activity to inhibit tumor necrosis factor-α secretion. Thus, our data show that Kupffer cell inactivation is an important step in order to improve ASC transplantation efficiency and therapeutic potential in liver injuries. In addition, the hepatoprotective function of glycine has synergic effects on liver protection and the engraftment of ASCs.

Therapeutic effect of transplantation of human amniotic membrane- and umbilical cord-derived mesenchymal stem cells on hepatic cirrhosis in rats

AIM: To evaluate the therapeutic effect of transplantation of human amniotic membrane-derived mesenchymal stem cells (hAM-MSCs) and human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) on carbon tetrachloride (CCl₄)-induced hepatic cirrhosis in rats.

METHODS: hAM-MSCs and hUC-MSCs were isolated and analyzed by flow cytometry for detection of expression of CD44, CD29 and CD34. Hepatic cirrhosis was induced in rats with CCl₄. At week 8, five rats were killed to conduct pathological examination to confirm successful induction of hepatic cirrhosis, and 30 rats with hepatic cirrhosis were randomly and equally divided into three groups: hAM-MSCs group, hUC-MSCs group and control group. The hAM-MSCs and hUC-MSCs groups were infused wit 2×10⁶ MSCs in 2 mL of saline via the tail vein, while the control group was given equal volume of saline. Liver function was examined before cell transplantation and 4 wk after cell transplantation. HE staining and Masson dyeing were performed to observe pathological changes in the liver. The expression of alpha-smooth muscle actin (α-SMA) in the liver was determined by immunohistochemistry.

RESULTS: Both isolated hAM-MSCs and hUC-MSCs expressed CD29 and CD44, but did not express CD34. After cell transplantation, liver function parameters were markedly improved (all P < 0.05) and the expression of α-SMA was reduced in the hAM-MSCs and hUC-MSCs groups compared to the control group (130.6 ± 3.0, 127.0 ± 2.6 vs 152.2 ± 5.4, both P < 0.05). There were no statistically significant differences in liver function parameters and α-SMA expression between the hAM-MSCs and hUC-MSCs groups.

CONCLUSION: Transplantation of hAM-MSCs and hUC-MSCs could efficiently improve liver functions and inhibit liver fibrosis in rats.

Comparison of immunomodulatory effects of placenta mesenchymal stem cells with bone marrow and adipose mesenchymal stem cells

Mesenchymal stem cells (MSCs) are powerful sources for cell therapy in regenerative medicine because they can be isolated from various tissues, expanded, and induced into multiple-lineages. Of note, their immunomodulatory effects maximize the therapeutic effects of stem cells engrafted on host, making them an especially attractive choice. Recently, several varieties of placenta-derived stem cells (PDSCs) including chorionic plate-derived MSCs (CP-MSCs) have been suggested as alternative sources of stem cells. However, comparative studies of immunomodulatory effects for CP-MSCs among various MSCs are largely lacking. We examined and compared immunomodulatory function of CP-MSCs with that of BM-MSCs and AD-MSCs using co-culture system with activated T-cells derived from human umbilical cord blood (UCB) exposed to anti-CD3 and anti-CD28 which are T-cell activating monoclonal antibodies. All MSCs expressed markers of stem cells and three germ layers by RT-PCR. These cells also exhibited comparable immunomodulatory effects when they were co-cultured with activated T-cells in dose-dependent manner. However, expression of HLA-ABC and HLA-G was highly positive in CP-MSCs compared to other MSCs, and higher levels of cytokines of IL-2, IL-4, IL-13, and GM-CSF were detected in dose-dependent manner in CP-MSCs. Taken together, the results of the present study suggest that while CP-MSCs, BM-MSCs, and AD-MSCs all have immunomodulatory effects, CP-MSCs may have additional advantage over the other MSCs in terms of immunomodulation. In conjunction with other previous studies, CP-MSCs are suggested to be a useful stem cell source in cell therapy.

Human term placental cells: phenotype, properties and new avenues in regenerative medicine

The human placenta has long been the subject of scientific interest due to the important roles which it performs during pregnancy in sustaining the fetus and maintaining fetomaternal tolerance. More recently, however, researchers have begun to investigate the possibility that the placenta's utility may extend beyond fetal development to act as a source of cells with clinically relevant properties. Indeed, several groups have reported the isolation of cells from different placental regions which display both multilineage differentiation potential and immunomodulatory properties in vitro. Furthermore, these cells have also been shown to secrete soluble factors involved in pathophysiological processes that may aid tissue repair. Cells with such features will clearly find application in the field of regenerative medicine for the repair/regeneration of damaged or diseased tissues or organs. In line with these promising findings, several preclinical and clinical studies conducted to date argue in strong favor of the therapeutic utility of placenta-derived cells for the treatment of several diseases. Although much work remains to be conducted in order to fully understand the properties of placental cells and the mechanisms which underlie their beneficial effects in vivo, data reported to date nonetheless provide compelling evidence in support of the placenta as a cell source for use in regenerative medicine.

Bone marrow-derived mesenchymal stem cells ameliorate hepatic ischemia reperfusion injury in a rat model

BACKGROUND

Ischemia-reperfusion (I/R) injury associated with living donor liver transplantation impairs liver graft regeneration. Mesenchymal stem cells (MSCs) are potential cell therapeutic targets for liver disease. In this study, we demonstrate the impact of MSCs against hepatic I/R injury and hepatectomy.

METHODOLOGY/PRINCIPAL FINDINGS

We used a new rat model in which major hepatectomy with I/R injury was performed. Male Lewis rats were separated into two groups: an MSC group given MSCs after reperfusion as treatment, and a Control group given phosphate-buffered saline after reperfusion as placebo. The results of liver function tests, pathologic changes in the liver, and the remnant liver regeneration rate were assessed. The fate of transplanted MSCs in the luciferase-expressing rats was examined by in vivo luminescent imaging. The MSC group showed peak luciferase activity of transplanted MSCs in the remnant liver 24 h after reperfusion, after which luciferase activity gradually declined. The elevation of serum alanine transaminase levels was significantly reduced by MSC injection. Histopathological findings showed that vacuolar change was lower in the MSC group compared to the Control group. In addition, a significantly lower percentage of TUNEL-positive cells was observed in the MSC group compared with the controls. Remnant liver regeneration rate was accelerated in the MSC group.

CONCLUSIONS/SIGNIFICANCE

These data suggest that MSC transplantation provides trophic support to the I/R-injured liver by inhibiting hepatocellular apoptosis and by stimulating regeneration.

Bone marrow-derived mesenchymal stem cells ameliorate hepatic ischemia reperfusion injury in a rat model

BACKGROUND

Ischemia-reperfusion (I/R) injury associated with living donor liver transplantation impairs liver graft regeneration. Mesenchymal stem cells (MSCs) are potential cell therapeutic targets for liver disease. In this study, we demonstrate the impact of MSCs against hepatic I/R injury and hepatectomy.

METHODOLOGY/PRINCIPAL FINDINGS

We used a new rat model in which major hepatectomy with I/R injury was performed. Male Lewis rats were separated into two groups: an MSC group given MSCs after reperfusion as treatment, and a Control group given phosphate-buffered saline after reperfusion as placebo. The results of liver function tests, pathologic changes in the liver, and the remnant liver regeneration rate were assessed. The fate of transplanted MSCs in the luciferase-expressing rats was examined by in vivo luminescent imaging. The MSC group showed peak luciferase activity of transplanted MSCs in the remnant liver 24 h after reperfusion, after which luciferase activity gradually declined. The elevation of serum alanine transaminase levels was significantly reduced by MSC injection. Histopathological findings showed that vacuolar change was lower in the MSC group compared to the Control group. In addition, a significantly lower percentage of TUNEL-positive cells was observed in the MSC group compared with the controls. Remnant liver regeneration rate was accelerated in the MSC group.

CONCLUSIONS/SIGNIFICANCE

These data suggest that MSC transplantation provides trophic support to the I/R-injured liver by inhibiting hepatocellular apoptosis and by stimulating regeneration.

The role of microvesicles in tissue repair

Microvesicles (MVs) are released by almost all cells in resting and activated conditions. First described several years ago, it is only recently that their mechanisms of action are being elucidated, and their potential role in health and disease is drawing increasing attention. The main function of MVs is signaling through specific interactions with target cells and the transferring of gene products. Gaining further insights into the molecular specificity of MVs has allowed identification of the cellular source and may provide new diagnostic tools in the future. Indeed, an increasing body of evidence indicates that MVs are capable of mediating tissue repair in models of acute kidney and liver injury. In this review, we will discuss the mechanisms through which MVs from stem cells may act on target cells and may modify the response to injury. Furthermore, MVs from inflammatory cells are suspected to be involved in various diseases, such as cardiovascular and renal diseases, pathological pregnancy, tumors and sepsis. MVs are no doubt also involved in modulating immunity, and future studies will clarify their functional role in negatively modulating the cell response. Their role in physiological and pathological processes is increasingly appreciated. Depending on the cell source and the condition, MVs may be either beneficial or detrimental to the host. The recognition of their pathogenetic role may suggest new approaches to future therapies.