Human fetal liver-derived stem cell transplantation as supportive modality in the management of end-stage decompensated liver cirrhosis

A New High Throughput Screening Platform for Cell Encapsulation in Alginate Hydrogel Shows Improved Hepatocyte Functions by Mesenchymal Stromal Cells Co-encapsulation

Hepatocyte transplantation has emerged as an alternative to liver transplant for liver disease. Hepatocytes encapsulated in alginate microbeads have been proposed for the treatment of acute liver failure, as they are able to provide hepatic functions while the liver regenerates. Furthermore, they do not require immunosuppression, as the alginate protects the hepatocytes from the recipient's immune cells. Mesenchymal stromal cells are very attractive candidates for regenerative medicine, being able to differentiate into cells of the mesenchymal lineages and having extensive proliferative ability. When co-cultured with hepatocytes in two-dimensional cultures, they exert a trophic role, drastically improving hepatocytes survival and functions. In this study we aimed to (i) devise a high throughput system (HTS) to allow testing of a variety of different parameters for cell encapsulation and (ii) using this HTS, investigate whether mesenchymal stromal cells could have beneficial effects on the hepatocytes when co-encapsulated in alginate microbeads. Using our HTS platform, we observed some improvement of hepatocyte behavior with MSCs, subsequently confirmed in the low throughput analysis of cell function in alginate microbeads. Therefore, our study shows that mesenchymal stromal cells may be a good option to improve the function of hepatocytes microbeads. Furthermore, the platform developed may be used for HTS studies on cell encapsulation, in which several conditions (e.g., number of cells, combinations of cells, alginate modifications) could be easily compared at the same time.

Engraftment of Human Pluripotent Stem Cell-derived Progenitors in the Inner Ear of Prenatal Mice

There is, at present, no curative treatment for genetic hearing loss. We have previously reported that transuterine gene transfer of wild type CONNEXIN30 (CX30) genes into otocysts in CX30-deleted mice could restore hearing. Cell transplantation therapy might be another therapeutic option, although it is still unknown whether stem cell-derived progenitor cells could migrate into mouse otocysts. Here, we show successful cell transplantation of progenitors of outer sulcus cell-like cells derived from human-derived induced pluripotent stem cells into mouse otocysts on embryonic day 11.5. The delivered cells engrafted more frequently in the non-sensory region in the inner ear of CX30-deleted mice than in wild type mice and survived for up to 1 week after transplantation. Some of the engrafted cells expressed CX30 proteins in the non-sensory region. This is the first report that demonstrates successful engraftment of exogenous cells in prenatal developing otocysts in mice. Future studies using this mouse otocystic injection model in vivo will provide further clues for developing treatment modalities for congenital hearing loss in humans.

Current Perspectives Regarding Stem Cell-Based Therapy for Liver Cirrhosis

Liver cirrhosis is a major cause of mortality and a common end of various progressive liver diseases. Since the effective treatment is currently limited to liver transplantation, stem cell-based therapy as an alternative has attracted interest due to promising results from preclinical and clinical studies. However, there is still much to be understood regarding the precise mechanisms of action. A number of stem cells from different origins have been employed for hepatic regeneration with different degrees of success. The present review presents a synopsis of stem cell research for the treatment of patients with liver cirrhosis according to the stem cell type. Clinical trials to date are summarized briefly. Finally, issues to be resolved and future perspectives are discussed with regard to clinical applications.

Stem/Progenitor Cell Niches Involved in Hepatic and Biliary Regeneration

Niches containing stem/progenitor cells are present in different anatomical locations along the human biliary tree and within liver acini. The most primitive stem/progenitors, biliary tree stem/progenitor cells (BTSCs), reside within peribiliary glands located throughout large extrahepatic and intrahepatic bile ducts. BTSCs are multipotent and can differentiate towards hepatic and pancreatic cell fates. These niches' matrix chemistry and other characteristics are undefined. Canals of Hering (bile ductules) are found periportally and contain hepatic stem/progenitor cells (HpSCs), participating in the renewal of small intrahepatic bile ducts and being precursors to hepatocytes and cholangiocytes. The niches also contain precursors to hepatic stellate cells and endothelia, macrophages, and have a matrix chemistry rich in hyaluronans, minimally sulfated proteoglycans, fetal collagens, and laminin. The microenvironment furnishes key signals driving HpSC activation and differentiation. Newly discovered third niches are pericentral within hepatic acini, contain Axin2+ unipotent hepatocytic progenitors linked on their lateral borders to endothelia forming the central vein, and contribute to normal turnover of mature hepatocytes. Their relationship to the other stem/progenitors is undefined. Stem/progenitor niches have important implications in regenerative medicine for the liver and biliary tree and in pathogenic processes leading to diseases of these tissues.

Therapeutic Potential of HGF-Expressing Human Umbilical Cord Mesenchymal Stem Cells in Mice with Acute Liver Failure

Human umbilical cord-derived mesenchymal stem cells (UCMSCs) are particularly attractive cells for cellular and gene therapy in acute liver failure (ALF). However, the efficacy of this cell therapy in animal studies needs to be significantly improved before it can be translated into clinics. In this study, we investigated the therapeutic potential of UCMSCs that overexpress hepatocyte growth factor (HGF) in an acetaminophen-induced acute liver failure mouse model. We found that the HGF-UCMSC cell therapy protected animals from acute liver failure by reducing liver damage and prolonging animal survival. The therapeutic effect of HGF-UCMSCs was associated with the increment in serum glutathione (GSH) and hepatic enzymes that maintain redox homeostasis, including γ-glutamylcysteine synthetase (γ-GCS), superoxide dismutase (SOD), and catalase (CAT). Immunohistochemical staining confirmed that HGF-UCMSCs were mobilized to the injured areas of the liver. Additionally, HGF-UCMSCs modulated apoptosis by upregulating the antiapoptotic Bcl2 and downregulating proapoptotic genes, including Bax and TNFα. Taken together, these data suggest that ectopic expression of HGF in UCMSCs protects animals from acetaminophen-induced acute liver failure through antiapoptosis and antioxidation mechanisms.

hVGAT-mCherry: A novel molecular tool for analysis of GABAergic neurons derived from human pluripotent stem cells

BACKGROUND

GABAergic synaptic transmission is known to play a critical role in the assembly of neuronal circuits during development and is responsible for maintaining the balance between excitatory and inhibitory signaling in the brain during maturation into adulthood. Importantly, defects in GABAergic neuronal function and signaling have been linked to a number of neurological diseases, including autism spectrum disorders, schizophrenia, and epilepsy. With patient-specific induced pluripotent stem cell (iPSC)-based models of neurological disease, it is now possible to investigate the disease mechanisms that underlie deficits in GABAergic function in affected human neurons. To that end, tools that enable the labeling and purification of viable GABAergic neurons from human pluripotent stem cells would be of great value.

RESULTS

To address the need for tools that facilitate the identification and isolation of viable GABAergic neurons from the in vitro differentiation of iPSC lines, a cell type-specific promoter-driven fluorescent reporter construct was developed that utilizes the human vesicular GABA transporter (hVGAT) promoter to drive the expression of mCherry specifically in VGAT-expressing neurons. The transduction of iPSC-derived forebrain neuronal cultures with the hVGAT promoter-mCherry lentiviral reporter construct specifically labeled GABAergic neurons. Immunocytochemical analysis of hVGAT-mCherry expression cells showed significant co-labeling with the GABAergic neuronal markers for endogenous VGAT, GABA, and GAD67. Expression of mCherry from the VGAT promoter showed expression in several cortical interneuron subtypes to similar levels. In addition, an effective and reproducible protocol was developed to facilitate the fluorescent activated cell sorting (FACS)-mediated purification of high yields of viable VGAT-positive cells.

CONCLUSIONS

These studies demonstrate the utility of the hVGAT-mCherry reporter construct as an effective tool for studying GABAergic neurons differentiated in vitro from human pluripotent stem cells. This approach could provide a means of obtaining large quantities of viable GABAergic neurons derived from disease-specific hiPSCs that could be used for functional assays or high-throughput screening of small molecule libraries.

Electrical maturation of neurons derived from human embryonic stem cells

In-vitro neuronal differentiation of human pluripotent stem cells has become a widely used tool in disease modeling and prospective regenerative medicine. Most studies evaluate neurons molecularly and only a handful of them use electrophysiological tools to directly indicate that these are genuine neurons. Therefore, the specific timing of development of intrinsic electrophysiological properties and synaptic capabilities remains poorly understood. Here we describe a systematic analysis of developing neurons derived in-vitro from human embryonic stem cells (hESCs). We show that hESCs differentiated in-vitro into early embryonic neurons, displaying basically mature morphological and electrical features as early as day 37. This early onset of action potential discharges suggests that first stages of neurogenesis in humans are already associated with electrical maturation. Spike frequency, amplitude, duration, threshold and after hyperpolarization were found to be the most predictive parameters for electrical maturity. Furthermore, we were able to detect spontaneous synaptic activity already at these early time-points, demonstrating that neuronal connectivity can develop concomitantly with the gradual process of electrical maturation. These results highlight the functional properties of hESCs in the process of their development into neurons. Moreover, our results provide practical tools for the direct measurement of functional maturity, which can be reproduced and implemented for stem cell research of neurogenesis in general, and neurodevelopmental disorders in particular.

Getting it right before transplantation: example of a stem cell model with regenerative potential for the CNS

The burden of neurodegenerative disorders in an aging population has become a challenge for the modern world. While the biomarkers available and the methods of diagnosis have improved to detect the onset of these diseases at early stages, the question of adapted and efficient therapies is still a major issue. The prospect of replacing the loss of functional neural cells remains an attractive but still audacious approach. A huge progress has been made in the generation of neurons derived from human stem cell lines and transplantation assays are tested in animals for a wide range of pathologies of the central nervous system. Here we take one step back and examine neuronal differentiation and the characterization of neural progenitors derived from human embryonic stem cells. We gather results from our previous studies and present a cell model that was successfully used in functional analyses and engraftment experiments. These neuronal precursors exhibit spontaneous and evoked activity, indicating that their electrophysiological and calcium handling properties are similar to those of matured neurons. Hence this summarized information will serve as a basis to design better stem cell-based therapies to improve neural regeneration.

Changes in expression pattern of selected endometrial proteins following mesenchymal stem cells infusion in mares with endometrosis

Mesenchymal stem cells (MSCs) due to their self-renewal potential and differentiation capacity are useful for tissue regeneration. Immunomodulatory and trophic properties of MSCs were demonstrated suggesting their use as medicinal signaling cells able to positively change local environment in injured tissue. Equine endometrosis is a progressive degenerative disease responsible for glandular alterations and endometrial fibrosis which causes infertility in mares. More precisely, this disease is characterized by phenotypic changes in the expression pattern of selected endometrial proteins. Currently, no effective treatment is available for endometrosis. Herein, we aimed at the evaluation of expression pattern of these proteins after allogeneic equine adipose tissue-derived multipotent mesenchymal stem cells (eAT-MSCs) infusion as well as at testing the capacity of these cells to promote endometrial tissue remodeling in mares with endometrosis. eAT-MSC (2×10⁷/animal) were transplanted into mares’ uterus and control animals received only placebo. Uterine biopsies were collected before (day 0) and after (days 7, 21 and 60) cells transplantation. Conventional histopathology as well as expression analysis of such proteins as laminin, vimentin, Ki-67-antigen, α-smooth muscle actin (α-SMA) and cytokeratin 18 (CK18) have been performed before and after eAT-MSCs transplantation. We demonstrated that eAT-MSCs induced early (at day 7) remodeling of endometrial tissue microenvironment through changes observed in intra cellular and intra glandular localization of aforementioned proteins. We demonstrated that eAT-MSCs were able to positively modulate the expression pattern of studied secretory proteins as well as, to promote the induction of glandular epithelial cells proliferation suggesting local benefits to committed endometrial tissue environment after eAT-MSCs transplantation.

Multifaceted roles of BDNF and FGF2 in human striatal primordium development. An in vitro study

Grafting fetal striatal cells into the brain of Huntington's disease (HD) patients has raised certain expectations in the past decade as an effective cell-based-therapy for this devastating condition. We argue that the first requirement for successful transplantation is defining the window of plasticity for the striatum during development when the progenitor cells, isolated from their environment, are able to maintain regional-specific-identity and to respond appropriately to cues. The primary cell culture from human fetal striatal primordium described here consists of a mixed population of neural stem cells, neuronal-restricted progenitors and striatal neurons. These cells express trophic factors, such as BDNF and FGF2. We show that these neurotrophins maintain cell plasticity, inducing the expression of neuronal precursor markers and cell adhesion molecules, as well as promoting neurogenesis, migration and survival. We propose that BDNF and FGF2 play an important autocrine-paracrine role during early striatum development in vivo and that their release by fetal striatal grafts may be relevant in the setting of HD cell therapy.

Human embryonic stem cell-derived oligodendrocytes: protocols and perspectives

Oligodendrocytes play a fundamental supportive role in the mammalian central nervous system (CNS) as the myelinating-glial cells. Disruption of fast axonal transport mechanisms can occur as a consequence of mature oligodendrocyte loss following spinal cord injury, stroke, or due to neuroinflammatory conditions, such as multiple sclerosis. As a result of the limited remyelination ability in the CNS after injury or disease, human embryonic stem cells (hESCs) may prove to be a promising option for the generation and replacement of mature oligodendrocytes. Moreover, hESC-derived oligodendrocytes may be experimentally utilized to unravel fundamental questions of oligodendrocyte development, along with their therapeutic potential through growth factor support of axons and neurons. However, an intensive characterization and examination of hESC-derived oligodendrocytes prior to preclinical or clinical trials is required to facilitate greater success in their integration following cellular replacement therapy (CRT). Currently, the protocols utilized to derive oligodendrocytes from hESCs consist of significant variations in culture style, time-length of differentiation, and the provision of growth factors in culture. Further, these differing protocols also report disparate patterns in the expression of oligodendroglial markers by these derived oligodendrocytes, throughout their differentiation in culture. We have comprehensively reviewed the published protocols describing the derivation of oligodendrocytes from hESCs and the studies that examine their efficacy to remyelinate, along with the fundamental issues of their safety as a viable CRT. Additionally, this review will highlight particular issues of concern and suggestions for troubleshooting to provide investigators critical information for the future improvement of establishing in vitro hESC-derived oligodendrocytes.

Plasticity of calcium signaling cascades in human embryonic stem cell-derived neural precursors

Human embryonic stem cell-derived neural precursors (hESC NPs) are considered to be a promising tool for cell-based therapy in central nervous system injuries and neurodegenerative diseases. The Ca(2+) ion is an important intracellular messenger essential for the regulation of various cellular functions. We investigated the role and physiology of Ca(2+) signaling to characterize the functional properties of CCTL14 hESC NPs during long-term maintenance in culture (in vitro). We analyzed changes in cytoplasmic Ca(2+) concentration ([Ca(2+)]i) evoked by high K(+), adenosine-5'-triphosphate (ATP), glutamate, γ-aminobutyric acid (GABA), and caffeine in correlation with the expression of various neuronal markers in different passages (P6 through P10) during the course of hESC differentiation. We found that only differentiated NPs from P7 exhibited significant and specific [Ca(2+)]i responses to various stimuli. About 31% of neuronal-like P7 NPs exhibited spontaneous [Ca(2+)]i oscillations. Pharmacological and immunocytochemical assays revealed that P7 NPs express L- and P/Q-type Ca(2+) channels, P2X2, P2X3, P2X7, and P2Y purinoreceptors, glutamate receptors, and ryanodine (RyR1 and RyR3) receptors. The ATP- and glutamate-induced [Ca(2+)]i responses were concentration-dependent. Higher glutamate concentrations (over 100 μM) caused cell death. Responses to ATP were observed in the presence or in the absence of extracellular Ca(2+). These results emphasize the notion that with time in culture, these cells attain a transient period of operative Ca(2+) signaling that is predictive of their ability to act as stem elements.

Stem cells in regenerative medicine

BACKGROUND

A number of cardiovascular, neurological, musculoskeletal and other diseases have a limited capacity for repair and only a modest progress has been made in treatment of brain diseases. The discovery of stem cells has opened new possibilities for the treatment of these maladies, and cell therapy now stands at the cutting-edge of modern regenerative medicine and tissue engineering. Experimental data and the first clinical trials employing stem cells have shown their broad therapeutic potential and have brought hope to patients suffering from devastating pathologies of different organs and systems.

AIMS

Here, we briefly review the main achievements and trends in cell-based therapy, with an emphasis on the main types of stem cells: embryonic, mesenchymal stromal and induced pluripotent cells.

DISCUSSION

Many questions regarding the application of stem cells remain unanswered, particularly tumorigenicity, immune rejection and danger of gene manipulation. Currently, only MSC seems to be safe and might be considered to be a leading candidate for human application to treat pathologies that affect the cardiovascular, neurological and musculoskeletal systems.

Stem cells in regenerative medicine

BACKGROUND

A number of cardiovascular, neurological, musculoskeletal and other diseases have a limited capacity for repair and only a modest progress has been made in treatment of brain diseases. The discovery of stem cells has opened new possibilities for the treatment of these maladies, and cell therapy now stands at the cutting-edge of modern regenerative medicine and tissue engineering. Experimental data and the first clinical trials employing stem cells have shown their broad therapeutic potential and have brought hope to patients suffering from devastating pathologies of different organs and systems.

AIMS

Here, we briefly review the main achievements and trends in cell-based therapy, with an emphasis on the main types of stem cells: embryonic, mesenchymal stromal and induced pluripotent cells.

DISCUSSION

Many questions regarding the application of stem cells remain unanswered, particularly tumorigenicity, immune rejection and danger of gene manipulation. Currently, only MSC seems to be safe and might be considered to be a leading candidate for human application to treat pathologies that affect the cardiovascular, neurological and musculoskeletal systems.

Liver bioengineering: Current status and future perspectives

The present review aims to illustrate the strategies that are being implemented to regenerate or bioengineer livers for clinical purposes. There are two general pathways to liver bioengineering and regeneration. The first consists of creating a supporting scaffold, either synthetically or by decellularization of human or animal organs, and seeding cells on the scaffold, where they will mature either in bioreactors or in vivo. This strategy seems to offer the quickest route to clinical translation, as demonstrated by the development of liver organoids from rodent livers which were repopulated with organ specific cells of animal and/or human origin. Liver bioengineering has potential for transplantation and for toxicity testing during preclinical drug development. The second possibility is to induce liver regeneration of dead or resected tissue by manipulating cell pathways. In fact, it is well known that the liver has peculiar regenerative potential which allows hepatocyte hyperplasia after amputation of liver volume. Infusion of autologous bone marrow cells, which aids in liver regeneration, into patients was shown to be safe and to improve their clinical condition, but the specific cells responsible for liver regeneration have not yet been determined and the underlying mechanisms remain largely unknown. A complete understanding of the cell pathways and dynamics and of the functioning of liver stem cell niche is necessary for the clinical translation of regenerative medicine strategies. As well, it will be crucial to elucidate the mechanisms through which cells interact with the extracellular matrix, and how this latter supports and drives cell fate.

Biomaterials combined with cell therapy for treatment of spinal cord injury

Spinal cord injury (SCI) is a devastating traumatic injury resulting in paralysis or sensory deficits due to tissue damage and the poor ability of axons to regenerate across the lesion. Despite extensive research, there is still no effective treatment that would restore lost function after SCI. A possible therapeutic approach would be to bridge the area of injury with a bioengineered scaffold that would create a stimulatory environment as well as provide guidance cues for the re-establishment of damaged axonal connections. Advanced scaffold design aims at the fabrication of complex materials providing the concomitant delivery of cells, neurotrophic factors or other bioactive substances to achieve a synergistic effect for treatment. This review summarizes the current utilization of scaffolding materials for SCI treatment in terms of their physicochemical properties and emphasizes their use in combination with various cell types, as well as with other combinatorial approaches promoting spinal cord repair.

Expression analysis of pluripotency-associated genes in human fetal cortical and striatal neural stem cells during differentiation

In the field of developmental biology, there is compelling evidence for a network of activity of pluripotency and stem-associated genes comprising of Oct4, Nanog and nestin. During neurogenesis, the choice between enhancement versus suppression of transcriptional modulation of these identified genes determines the balance between self-renewal neural stem cells (NSC) and immature neuronal phenotypes. By using immunocytochemistry and RT-PCR techniques, our study aims to address the question whether and to what extent mRNA and protein profiles are expressed in human fetal neurospheres obtained from cortical and striatal brain regions, both in expansion (undifferentiated cells) and differentiation conditions monitored after 1 and 4 weeks in vitro culturing. Our results clearly demonstrate the sustained presence of opposite signals: strong downregulation of Oct4 and Nanog genes in cortical differentiating cells and significant up-regulation for nestin gene both in cortical and striatal differentiating cells. Notably, by immunostaining techniques, Oct4 and Nanog protein expression have indicated the presence of both nuclear and cytoplasmic content followed by their rapid turnover (immediately after 1 week). Moreover, during the differentiation process, dissociated neurospheres displayed unexpected number of nestin positive cells accompanied by a constant level of staining intensity. In conclusion, the present study provides new insights into brain region related features in terms of Oct4, Nanog and nestin expression both at cellular and molecular level.