Stem cell-based therapy in gastroenterology and hepatology

Direct and indirect effects of pathogenic bacteria on the integrity of intestinal barrier

Bacterial translocation is a pathological process involving migration of pathogenic bacteria across the intestinal barrier to enter the systemic circulation and gain access to distant organs. This phenomenon has been linked to a diverse range of diseases including inflammatory bowel disease, pancreatitis, and cancer. The intestinal barrier is an innate structure that maintains intestinal homeostasis. Pathogenic infections and dysbiosis can disrupt the integrity of the intestinal barrier, increasing its permeability, and thereby facilitating pathogen translocation. As translocation represents an essential step in pathogenesis, a clear understanding of how barrier integrity is disrupted and how this disruption facilitates bacterial translocation could identify new routes to effective prophylaxis and therapy. In this comprehensive review, we provide an in-depth analysis of bacterial translocation and intestinal barrier function. We discuss currently understood mechanisms of bacterial-enterocyte interactions, with a focus on tight junctions and endocytosis. We also discuss the emerging concept of bidirectional communication between the intestinal microbiota and other body systems. The intestinal tract has established 'axes' with various organs. Among our regulatory systems, the nervous, immune, and endocrine systems have been shown to play pivotal roles in barrier regulation. A mechanistic understanding of intestinal barrier regulation is crucial for the development of personalized management strategies for patients with bacterial translocation-related disorders. Advancing our knowledge of barrier regulation will pave the way for future research in this field and novel clinical intervention strategies.

Tissue engineering of the gastrointestinal tract: the historic path to translation

The gastrointestinal (GI) tract is imperative for multiple functions including digestion, nutrient absorption, and timely waste disposal. The central feature of the gut is peristalsis, intestinal motility, which facilitates all of its functions. Disruptions in GI motility lead to sub-optimal GI function, resulting in a lower quality of life in many functional GI disorders. Over the last two decades, tissue engineering research directed towards the intestine has progressed rapidly due to advances in cell and stem-cell biology, integrative physiology, bioengineering and biomaterials. Newer biomedical tools (including optical tools, machine learning, and nuanced regenerative engineering approaches) have expanded our understanding of the complex cellular communication within the GI tract that lead to its orchestrated physiological function. Bioengineering therefore can be utilized towards several translational aspects: (i) regenerative medicine to remedy/restore GI physiological function; (ii) in vitro model building to mimic the complex physiology for drug and pharmacology testing; (iii) tool development to continue to unravel multi-cell communication networks to integrate cell and organ-level physiology. Despite the significant strides made historically in GI tissue engineering, fundamental challenges remain including the quest for identifying autologous human cell sources, enhanced scaffolding biomaterials to increase biocompatibility while matching viscoelastic properties of the underlying tissue, and overall biomanufacturing. This review provides historic perspectives for how bioengineering has advanced over time, highlights newer advances in bioengineering strategies, and provides a realistic perspective on the path to translation.

Intestinal ex vivo organoid culture reveals altered programmed crypt stem cells in patients with celiac disease

The ex vivo generation of gastrointestinal organoids from crypt stem cells opens up the possibility of new research approaches investigating gastrointestinal diseases. We used this technology to study differences between healthy controls and patients with celiac disease (CD). We noticed distinct dissimilarities in the phenotypes of organoids between our study groups and found considerable variations in their gene expression. Extracellular matrix genes involved in epithelial-mesenchymal transition are expressed most differently. In addition, we demonstrated epigenetic modifications that might be responsible for the different organoid gene expression thus accounting for a deranged crypt/villus axis development in CD. The organoids have proven valuable to demonstrate fundamental differences in duodenal derived organoids between healthy controls and patients with CD and thus are a suitable tool to gain new insights in pathogenesis of CD.

Circulating hematopoietic stem cells and putative intestinal stem cells in coeliac disease

Background

The intestinal stem cells (ISC) modulation and the role of circulating hematopoietic stem cells (HSC) in coeliac disease (CD) are poorly understood. Our aim was to investigate the longitudinal modifications in peripheral blood HSC traffic and putative ISC density induced by gluten-free diet (GFD) in CD.

Methods

Thirty-one CD patients and 7 controls were enrolled. Circulating CD133⁺ and CD34⁺ HSC were measured by flow cytometry, at enrolment and after 7 days and 1, 3, 6, 12, and 24 months of GFD. Endoscopy was performed at diagnosis and repeated at 6, 12, and 24 months following GFD. We used the Marsh-Oberhuber score to evaluate the histological severity of duodenal damage; immunohistochemistry was employed to measure the intraepithelial lymphoid infiltrate (IEL, CD3⁺ lymphoid cells) and the putative ISC compartment (CD133⁺ and Lgr5⁺ epithelial cells).

Results

At enrolment, circulating HSCs were significantly increased in CD patients and they further augmented during the first week of GFD, but progressively decreased afterwards. CD patients presented with villous atrophy, abundant IEL and rare ISC residing at the crypt base. Upon GFD, IEL progressively decreased, while ISC density increased, peaking at 12 months. After 24 months of GFD, all patients were asymptomatic and their duodenal mucosa was macroscopically and histologically normal.

Conclusions

In active CD patients, the ISC niche is depleted and there is an increased traffic of circulating HSC versus non-coeliac subjects. GFD induces a precocious mobilization of circulating HSC, which is followed by the expansion of the local ISC compartment, leading to mucosal healing and clinical remission.

Hepatic stem cells: A viable approach for the treatment of liver cirrhosis

Liver cirrhosis is characterized by distortion of liver architecture, necrosis of hepatocytes and regenerative nodules formation leading to cirrhosis. Various types of cell sources have been used for the management and treatment of decompensated liver cirrhosis. Knowledge of stem cells has offered a new dimension for regenerative therapy and has been considered as one of the potential adjuvant treatment modality in patients with end stage liver diseases (ESLD). Human fetal hepatic progenitor cells are less immunogenic than adult ones. They are highly propagative and challenging to cryopreservation. In our earlier studies we have demonstrated that fetuses at 10-18 wk of gestation age contain a large number of actively dividing hepatic stem and progenitor cells which possess bi-potent nature having potential to differentiate into bile duct cells and mature hepatocytes. Hepatic stem cell therapy for the treatment of ESLD is in their early stage of the translation. The emerging technology of decellularization and recellularization might offer a significant platform for developing bioengineered personalized livers to come over the scarcity of desired number of donor organs for the treatment of ESLD. Despite these significant advancements long-term tracking of stem cells in human is the most important subject nowadays in order to answer several unsettles issues regarding the route of delivery, the choice of stem cell type(s), the cell number and the time-point of cell delivery for the treatment in a chronic setting. Answering to these questions will further contribute to the development of safer, noninvasive, and repeatable imaging modalities that could discover better cell therapeutic approaches from bench to bed-side. Combinatorial approach of decellularization and nanotechnology could pave a way towards the better understanding in determination of cell fate post-transplantation.

Cellular therapies based on stem cells and their insulin-producing surrogates: a 2015 reality check

Stem cell technology has recently gained a substantial amount of interest as one method to create a potentially limitless supply of transplantable insulin-producing cells to treat, and possibly cure diabetes mellitus. In this review, we summarize the state-of-the art of stem cell technology and list the potential sources of stem cells that have been shown to be useful as insulin-expressing surrogates. We also discuss the milestones that have been reached and those that remain to be addressed to generate bona fide beta cell-similar, insulin-producing surrogates. The caveats, limitations, and realistic expectations are also considered for current and future technology. In spite of the tremendous technical advances realized in the past decade, especially in the field of reprogramming adult somatic cells to become stem cells, the state-of-the art still relies on lengthy and cumbersome in vitro culture methods that yield cell populations that are not particularly glucose-responsive when transplanted into diabetic hosts. Despite the current impediments toward clinical translation, including the potential for immune rejection, the availability of technology to generate patient-specific reprogrammable stem cells has, and will be critical for, important insights into the genetics, epigenetics, biology, and physiology of insulin-producing cells in normal and pathologic states. This knowledge could accelerate the time to reach the desired breakthrough for safe and efficacious beta cell surrogates.

Micron-sized iron oxide-containing particles for microRNA-targeted manipulation and MRI-based tracking of transplanted cells

Particle-based delivery systems for therapeutic manipulation and tracking of transplanted cells by magnetic resonance imaging (MRI) are commonly based on nanometer-sized superparamagnetic iron oxide particles (SPIOs). Here, we present a proof of concept for multifunctional, silica based micron-sized iron oxide-containing particles (sMPIO) that combine fluorescence imaging, MRI tracking, and on-the-spot targeting of specific microRNAs on a particle surface for therapeutic manipulation by RNA interference. Antisense locked nucleic acids (α-LNA) were covalently bound to the surface of silica-based, DAPI-integrated, micron-sized iron oxide particles (sMPIO-α-LNA). In vitro studies using primary human hepatocytes showed rapid particle uptake (4 h) that was accompanied by significant depletion of the targeted microRNA Let7g (80%), up-regulation of the target proteins Cyclin D1 and c-Myc, and specific proteome changes. sMPIO-α-LNA-labeled cells were successfully detected by fluorescence imaging and could be visualized by MRI after intrasplenic transplantation in rats. This new theranostic particle provides a promising tool for cell transplantation where cellular imaging and microRNA-based manipulation is needed. [165].

Intestinal stem cells and celiac disease

Stem cells (SCs) are the key to tissue genesis and regeneration. Given their central role in homeostasis, dysfunctions of the SC compartment play a pivotal role in the development of cancers, degenerative disorders, chronic inflammatory pathologies and organ failure. The gastrointestinal tract is constantly exposed to harsh mechanical and chemical conditions and most of the epithelial cells are replaced every 3 to 5 d. According to the so-called Unitarian hypothesis, this renewal is driven by a common intestinal stem cell (ISC) residing within the crypt base at the origin of the crypt-to-villus hierarchical migratory pattern. Celiac disease (CD) can be defined as a chronic immune-mediated disease that is triggered and maintained by dietary proteins (gluten) in genetically predisposed individuals. Many advances have been achieved over the last years in understanding of the pathogenic interactions among genetic, immunological and environmental factors in CD, with a particular emphasis on intestinal barrier and gut microbiota. Conversely, little is known about ISC modulation and deregulation in active celiac disease and upon a gluten-free diet. Nonetheless, bone marrow-derived SC transplantation has become an option for celiac patients with complicated or refractory disease. This manuscript summarizes the “state of the art” regarding CD and ISCs, their niche and potential role in the development and treatment of the disease.

Human stem-cell research in gastroenterology: experimental treatment, tourism and biobanking

The growing interest in the possibility of applying stem-cell therapies to gastroenterological diseases is outlined. Some promising results have been reported, but more research is needed in view of the uncertainties and knowledge gaps that still exist. The ethical issues raised by this kind of research are then indicated and classified. Three problematic kinds of situation are outlined: experimental treatments, stem-cell tourism and biobanking. A four-question approach - which is not to be confused with the well-known four-principle approach introduced by Beauchamp and Childress - is described and applied to these three challenging situations. In conclusion, it is pointed out that the analysis of these situations illustrates the interplay between definitions, empirical research and ethics. They are interrelated and need to be integrated.

Overexpression of microRNA-122 enhances in vitro hepatic differentiation of fetal liver-derived stem/progenitor cells

MicroRNAs (miRNAs) are a versatile class of tiny non-coding RNAs involved in regulation of various biological processes. miRNA-122 (miR-122) is specifically and abundantly expressed in human liver. However, the role of miR-122 in differentiation of fetal liver stem/progenitor cells into hepatocytes remains unclear. In this study, dual positive CD34+/CD117+ expressing human fetal liver stem/progenitor cells was enriched by magnetic cell sorting and cultured in vitro. The level of miR-122 was found to be increased at specific time intervals. Interestingly, during the differentiation process of hepatocyte-like cells, the increase in expression of miR-122 was positively correlated with expression of hepatocyte-specific genes. The status of differentiation process was improved by transfection of miR-122 into enriched stem/progenitor cells. The expression level of hepatic-specific genes as well as liver-enriched transcription factors (LETFs) was significantly increased by overexpression of miR-122 in fetal liver stem/progenitor cells. Thus, the study delineated the role of hepato-specific miR-122 in differentiation of fetal liver stem/progenitor cells into hepatocyte-like cells which could be used as a therapeutic target molecule to generate abundant hepatocytes.

[An introduction to biomaterials in urology]

Aim of this paper is to provide a brief introduction on the biomaterials used in urology, discussing issues of biocompatibility and biomaterials available for use. Information will moreover be provided on basic elements of Tissue engineering and Regenerative medicine, rapidly advancing technologies that could finally shift in the next future from the laboratory to clinical practice, with special interest to possible urological applications.

Isolation of viable human hepatic progenitors from adult livers is possible even after 48 hours of cold ischemia

Liver transplantation, utilized routinely for end-stage liver disease, has been constrained by the paucity of organ donors, and is being complemented by alternative strategies such as liver cell transplantation. One of the most promising forms of liver cell transplantation is hepatic stem cell therapies, as the number of human hepatic stem cells (hHpSCs) and other early hepatic progenitor cells (HPCs) are sufficient to provide treatment for multiple patients from a single liver source. In the present study, human adult livers were exposed to cold ischemia and then processed after <24 or 48 h. Cells positive for epithelial cell adhesion molecule (EpCAM), a marker on early lineage stage HPCs, were immunoselected and counted. Approximately 100,000 EpCAM(+) cells/gram of tissue was obtained from surgical resection of livers subjected to cold ischemia up to 24 h and comparable numbers, albeit somewhat lower, were obtained from those exposed to 48 h of cold ischemia. The yields are similar to those reported from livers with minimal exposure to ischemia. When cultured on plastic dishes and in Kubota's Medium, a serum-free medium designed for early lineage stage HPCs, colonies of rapidly expanding cells formed. They were confirmed to be probable hHpSCs by their ability to survive and expand on plastic and in Kubota's Medium for months, by co-expression of EpCAM and neural cell adhesion molecule, minimal if any albumin expression, with EpCAM found throughout the cells, and no expression of alpha-fetoprotein. The yields of viable EpCAM(+) cells were surprisingly large, and the numbers from a single donor liver are sufficient to treat approximately 50-100 patients given the numbers of EpCAM(+) cells currently used in hepatic stem cell therapies. Thus, cold ischemic livers for up to 48 h are a new source of cells that might be used for liver cell therapies.

Autologous gastrointestinal reconstruction: review of the optimal nontransplant surgical options for adults and children with short bowel syndrome

Short bowel syndrome (SBS) results in loss of absorptive capacity of the development of gut, leading to malabsorption due to protein, energy, fluid, and electrolyte loss and imbalance while on enteral diet alone. Various nonsurgical and surgical therapeutic options that have emerged improve the survival outcome following SBS in both children and adults. An individualized, complex multidisciplinary approach to medical and surgical intestinal rehabilitation is needed to provide an opportunity for enteral autonomy to be possible in a patient with SBS. The remnant bowel plays a very pivotal role in autologous gastrointestinal reconstruction (AGIR) surgery. Intestinal transplantation, although promising and potentially life-saving for SBS, should be reserved for patients with failed AGIR or those who have no prospect for autologous enteral autonomy. This article reviews the evolution of nontransplant surgical management of patients with SBS.

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.

[Stem cell properties of therapeutic potential]

Stem cell research is a innovative technology that focuses on using undifferentiated cells able to self-renew through the asymmetrical or symmetrical divisions. Three types of stem cells have been studied in laboratory including embryonic stem cell, adult stem cells and induced pluripotent stem cells. Embryonic stem cells are pluripotent stem cells derived from the inner cell mass and it can give rise to any fetal or adult cell type. Adult stem cells are multipotent, have the ability to differentiate into a limited number of specialized cell types, and have been obtained from the bone marrow, umbilical cord blood, placenta and adipose tissue. Stem cell therapy is the most promising therapy for several degenerative and devastating diseases including digestive tract disease such as liver failure, inflammatory bowel disease, Celiac sprue, and pancreatitis. Further understanding of biological properties of stem cells will lead to safe and successful stem cell therapies. (Korean J Gastroenterol 2011;58: 125-132).

Therapeutic application of stem cells in gastroenterology: An up-date

Adult stem cells represent the self-renewing progenitors of numerous body tissues, and they are currently classified according to their origin and differentiation ability. In recent years, the research on stem cells has expanded enormously and holds therapeutic promises for many patients suffering from currently disabling diseases. This paper focuses on the possible use of stem cells in the two main clinical settings in gastroenterology, i.e., hepatic and intestinal diseases, which have a strong impact on public health worldwide. Despite encouraging results obtained in both regenerative medicine and immune-mediated conditions, further studies are needed to fully understand the biology of stem cells and carefully assess their putative oncogenic properties. Moreover, the research on stem cells arouses fervent ethical, social and political debate. The Italian Society of Gastroenterology sponsored a workshop on stem cells held in Verona during the XVI Congress of the Federation of Italian Societies of Digestive Diseases (March 6-9, 2010). Here, we report on the issues discussed, including liver and intestinal diseases that may benefit from stem cell therapy, the biology of hepatic and intestinal tissue repair, and stem cell usage in clinical trials.

Molecular imaging of cell therapy for gastroenterologic applications

Stem cell therapy has appeared as a possible therapeutic alternative for numerous diseases. Furthermore, cancer stem cells are a focus of significant interest as they may allow for a better understanding of the genesis of different malignancies. The ultimate goal of stem cell therapeutics is to ensure the viability and functionality of the transplanted cells. Similarly, the ultimate goal of understanding cancer stem cells is to understand how they behave in the living subject. Until recently, the efficacy of stem cell therapies has been assessed by overall organ function recovery. Understanding the behavior and biology of stem cells directly in the living subject can also lead to therapy optimization. Thus, there is a critical need for reliable and accurate methods to understand stem cell biology in vivo. Recent advances in both imaging and molecular biology have enabled transplanted stem cells to be successfully monitored in the living subject. The use of molecular imaging modalities has the capability to answer these questions and may one day be translated to patients. In this review, we will discuss the potential imaging strategies and how they can be utilized, depending on the questions that need to be answered.

Regenerative medicine in urology

The term 'regenerative medicine' encompasses strategies for restoring or renewing tissue or organ function by: (i) in vivo tissue repair by in-growth of host cells into an acellular natural or synthetic biomaterial, (ii) implantation of tissue 'engineered'in vitro by seeding cultured cells into a biomaterial scaffold, and (iii) therapeutic cloning and stem cell-based tissue regeneration. In this article, we review recent developments underpinning the emerging science of regenerative medicine and critically assess where successful implementation of novel regenerative medicine approaches into urology practice might genuinely transform the quality of life of affected individuals. We advocate the need for an evidence-based approach supported by strong science and clinical objectivity.

CD133+ stem cell mobilization after partial hepatectomy depends on resection extent and underlying disease

BACKGROUND

Bone marrow stem cells (BMSC) can participate to liver regeneration. However, conflicting results have been reported on this topic in patients undergoing liver resection.

AIMS

To assess the impact of liver resection extent and presence of underlying liver disease in modulating BMSC mobilization.

METHODS

We enrolled 29 patients undergoing liver resection of different extents, 5 surgical controls and 10 blood donors. Circulating CD133+ BMSC were measured by flow cytometry at different time-points after surgery. The hepatic commitment of mobilized BMSC was investigated by polymerase chain reaction. Liver specimens were collected during surgery for histopathological analysis. Hepatocyte growth factor and granulocyte-colony stimulating factor serum levels were measured by enzyme-linked immunosorbent assay.

RESULTS

BMSC mobilization was found in patients undergoing major liver resection, especially in the presence of underlying disease. Ductular reactions were noted in patients with chronic hepatopathy and the hepatic progenitor-like cells expressed CD133, NCAM, cytokeratin-19, and alpha-fetoprotein. Hepatocyte growth factor and granulocyte-colony stimulating factor levels increased following liver resection and the contemporaneous presence of liver disease was associated with their highest raise.

CONCLUSIONS

Liver repair is mainly an endogenous process. BMSC become important in case of extensive resection, especially in the presence of underlying hepatopathy and hepatic progenitor-like cells activation. Hepatocyte growth factor and granulocyte-colony stimulating factor seem to be involved in the dynamics underlying hepatic regeneration and BMSC recruitment.

Stem cell-based therapies for liver diseases: state of the art and new perspectives

Millions of patients worldwide suffer from end-stage liver pathologies, whose only curative therapy is liver transplantation (OLT). Given the donor organ shortage, alternatives to OLT have been evaluated, including cell therapies. Hepatocyte transplantation has been attempted to cure metabolic liver disorders and end-stage liver diseases. The evaluation of its efficacy is complicated by the shortage of human hepatocytes and their difficult expansion and cryopreservation. Recent advances in cell biology have led to the concept of "regenerative medicine", based on the therapeutic potential of stem cells (SCs). Different types of SCs are theoretically eligible for liver cell replacement. These include embryonic and fetal SCs, induced pluripotent cells, annex SCs, endogenous liver SCs, and extrahepatic adult SCs. Aim of this paper is to critically analyze the possible sources of SCs suitable for liver repopulation and the results of the clinical trials that have been published until now.

Pluripotent plasticity of stem cells and liver repopulation

Different types of stem cells have a role in liver regeneration or fibrous repair during and after several liver diseases. Otherwise, the origin of hepatic and/or extra-hepatic stem cells in reactive liver repopulation is under controversy. The ability of the human body to self-repair and replace the cells and tissues of some organs is often evident. It has been estimated that complete renewal of liver tissue takes place in about a year. Replacement of lost liver tissues is accomplished by proliferation of mature hepatocytes, hepatic oval stem cells differentiation, and sinusoidal cells as support. Hepatic oval cells display a distinct phenotype and have been shown to be a bipotential progenitor of two types of epithelial cells found in the liver, hepatocytes, and bile ductular cells. In gastroenterology and hepatology, the first attempts to translate stem cell basic research into novel therapeutic strategies have been made for the treatment of several disorders, such as inflammatory bowel diseases, diabetes mellitus, celiachy, and acute or chronic hepatopaties. In the future, pluripotent plasticity of stem cells will open a variety of clinical application strategies for the treatment of tissue injuries, degenerated organs. The promise of liver stem cells lie in their potential to provide a continuous and readily available source of liver cells that can be used for gene therapy, cell transplant, bio-artificial liver-assisted devices, drug toxicology testing, and use as an in vitro model to understand the developmental biology of the liver.

Establishment of cancer cell lines from rat hepatocholangiocarcinoma and assessment of the role of granulocyte-colony stimulating factor and hepatocyte growth factor in their growth, motility and survival

BACKGROUND/AIMS

Oval cells (OCs), putative hepatic stem cells, may give rise to liver cancers. We developed a carcinogenesis regimen, based upon induction of OC proliferation prior to carcinogen exposure. In our model, rats subjected to 2-acetylaminofluorene/ partial-hepatectomy followed by aflatoxin injection (APA regimen) developed well-differentiated hepatocholangiocarcinomas. The aim of this study was to establish and characterize cancer cell lines from this animal model.

METHODS

Cancer cells were cultured from animals sacrificed eight months after treatment, and single clones were selected. The established cell lines, named LCSCs, were characterized, and their tumorigenicity was assessed in vivo. The roles of granulocyte-colony stimulating factor (G-CSF) and hepatocyte growth factor (HGF) in LCSC growth, survival and motility were also investigated.

RESULTS

From primary tumors, six cell lines were developed. LCSCs shared with the primary tumors the expression of various OC-associated markers, including cMet and G-CSF receptor. In vitro, HGF conferred protection from death by serum withdrawal. Stimulation with G-CSF increased LCSC growth and motility, while the blockage of its receptor inhibited LCSC proliferation and migration.

CONCLUSIONS

Six cancer cell lines were established from our model of hepatocholangiocarcinoma. HGF modulated LCSC resistance to apoptosis, while G-CSF acted on LCSCs as a proliferative and chemotactic agent.

Stem cells, a two-edged sword: Risks and potentials of regenerative medicine

The recent advancements in stem cell (SC) biology have led to the concept of regenerative medicine, which is based on the potential of SC for therapies aimed to facilitate the repair of degenerating or injured tissues. Nonetheless, prior to large scale clinical applications, critical aspects need to be further addressed, including the long-term safety, tolerability, and efficacy of SC-based treatments. Most problematic among the risks of SC-based therapies, in addition to the possible rejection or loss of function of the infused cells, is their potential neoplastic transformation. Indeed, SCs may be used to cure devastating diseases, but their specific properties of self-renewal and clonogenicity may render them prone to generate cancers. In this respect, ‘Stemness’ might be seen as a two-edged sword, its bright side being represented by normal SCs, its dark side by cancer SCs. A better understanding of SC biology will help fulfill the promise of regenerative medicine aimed at curing human pathologies and fighting cancer from its roots.