Embryonic stem cells: new possible therapy for degenerative diseases that affect elderly people

Generation of a stably transfected mouse embryonic stem cell line for inducible differentiation to excitatory neurons

In vitro differentiation of stem cells into various cell lineages is valuable in developmental studies and an important source of cells for modelling physiology and pathology, particularly for complex tissues such as the brain. Conventional protocols for in vitro neuronal differentiation often suffer from complicated procedures, high variability and low reproducibility. Over the last decade, the identification of cell fate-determining transcription factors has provided new tools for cellular studies in neuroscience and enabled rapid differentiation driven by ectopic transcription factor expression. As a proneural transcription factor, Neurogenin 2 (Ngn2) expression alone is sufficient to trigger rapid and robust neurogenesis from pluripotent cells. Here, we established a stable cell line, by piggyBac (PB) transposition, that conditionally expresses Ngn2 for generation of excitatory neurons from mouse embryonic stem cells (ESCs) using an all-in-one PB construct. Our results indicate that Ngn2-induced excitatory neurons have mature and functional characteristics consistent with previous studies using conventional differentiation methods. This approach provides an all-in-one PB construct for rapid and high copy number gene delivery of dox-inducible transcription factors to induce differentiation. This approach is a valuable in vitro cell model for disease modeling, drug screening and cell therapy.

Human Embryonic Stem-Cell-Derived Exosomes Repress NLRP3 Inflammasome to Alleviate Pyroptosis in Nucleus Pulposus Cells by Transmitting miR-302c

Recent studies have shown that the NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome is extensively activated in the process of intervertebral disc degeneration (IVDD), leading to the pyroptosis of nucleus pulposus cells (NPCs) and the exacerbation of the pathological development of the intervertebral disc (IVD). Exosomes derived from human embryonic stem cells (hESCs-exo) have shown great therapeutic potential in degenerative diseases. We hypothesized that hESCs-exo could alleviate IVDD by downregulating NLRP3. We measured the NLRP3 protein levels in different grades of IVDD and the effect of hESCs-exo on the H₂O₂-induced pyroptosis of NPCs. Our results indicate that the expression of NLRP3 was upregulated with the increase in IVD degeneration. hESCs-exo were able to reduce the H₂O₂-mediated pyroptosis of NPCs by downregulating the expression levels of NLRP3 inflammasome-related genes. Bioinformatics software predicted that miR-302c, an embryonic stem-cell-specific RNA, can inhibit NLRP3, thereby alleviating the pyroptosis of NPCs, and this was further verified by the overexpression of miR-302c in NPCs. In vivo experiments confirmed the above results in a rat caudal IVDD model. Our study demonstrates that hESCs-exo could inhibit excessive NPC pyroptosis by downregulating the NLRP3 inflammasome during IVDD, and miR-302c may play a key role in this process.

Pluripotent and Multipotent Stem Cells and Current Therapeutic Applications: Review

There is numerous evidence for the presence of stem cells, which is important for the treatment of a wide variety of disease conditions. Stem cells have a great therapeutic effect on different degenerative diseases through the development of specialized cells. Embryonic stem (ES) cells are derived from preimplantation embryos, which have a natural karyotype. This cell has the capacity of proliferation indefinitely and undifferentiated. Stem cells are very crucial for the treatment of different chronic and degenerative diseases. For instance, stem cell clinical trials have been done for ischemic heart disease. Also, the olfactory cells for spinal cord lesions and human fetal pancreatic cells for diabetes mellitus are the other clinical importance of stem cell therapy. Extracellular matrix (ECM) and other environmental factors influence the fate and activity of stem cells.

Role of Stem-Cell Transplantation in Leukemia Treatment

Stem cells (SCs) play a major role in advanced fields of regenerative medicine and other research areas. They are involved in the regeneration of damaged tissue or cells, due to their self-renewal characteristics. Tissue or cells can be damaged through a variety of diseases, including hematologic and nonhematologic malignancies. In regard to this, stem-cell transplantation is a cellular therapeutic approach to restore those impaired cells, tissue, or organs. SCs have a therapeutic potential in the application of stem-cell transplantation. Research has been focused mainly on the application of hematopoietic SCs for transplantation. Cord blood cells and human leukocyte antigen-haploidentical donors are considered optional sources of hematopoietic stem-cell transplantation. On the other hand, pluripotent embryonic SCs and induced pluripotent SCs hold promise for advancement of stem-cell transplantation. In addition, nonhematopoietic mesenchymal SCs play their own significant role as a functional bone-marrow niche and in the management of graft-vs-host disease effects during the posttransplantation process. In this review, the role of different types of SCs is presented with regard to their application in SC transplantation. In addition to this, the therapeutic value of autologous and allogeneic hematopoietic stem-cell transplantation is assessed with respect to different types of leukemia. Highly advanced and progressive scientific research has focused on the application of stem-cell transplantation on specific leukemia types. We evaluated and compared the therapeutic potential of SC transplantation with various forms of leukemia. This review aimed to focus on the application of SCs in the treatment of leukemia.

Therapeutic potential of mesenchymal stem cells for oral and systemic diseases

Mesenchymal stem cells (MSCs) are adult stem cells whose self-renewal, multipotency, and immunosuppressive functions have been investigated for therapeutic applications. MSCs have used for various systemic organ regenerative therapies, allowing rescue of tissue function in damaged or failing organs. This article reviews the regenerative and immunomodulatory functions of MSCs and their applications in dental, orofacial, and systemic tissue regeneration and treatment of inflammatory disorders. It also addresses challenges to MSC-mediated therapeutics arising from tissue and MSC aging and host immune response against allogenic MSC transplantation, and discusses alternative sources of MSCs aimed at overcoming these limitations.

Effects of selegiline, a monoamine oxidase B inhibitor, on differentiation of P19 embryonal carcinoma stem cells, into neuron-like cells

Selegiline, the irreversible inhibitor of monoamine oxidase B (MAO-B), is currently used to treat Parkinson's disease. However, the mechanism of action of selegiline is complex and cannot be explained solely by its MAO-B inhibitory action. It stimulates gene expression, as well as expression of a number of mRNAs or proteins in nerve and glial cells. Direct neuroprotective and anti-apoptotic actions of selegiline have previously been observed in vitro. Previous studies showed that selegiline can induce neuronal phenotype in cultured bone marrow stem cells and embryonic stem cells. Embryonal carcinoma (EC) cells are developmentally pluripotene cells which can be differentiated into all cell types under the appropriate conditions. The present study was carried out to examine the effects of selegiline on undifferentiated P19 EC cells. The results showed that selegiline treatment had a dramatic effect on neuronal morphology. It induced the differentiation of EC cells into neuron-like cells in a concentration-dependent manner. The peak response was in a dose of selegiline significantly lower than required for MAO-B inhibition. The differentiated cells were immunoreactive for neuron-specific proteins, synaptophysin, and β-III tubulin. Stem cell therapy has been considered as an ideal option for the treatment of neurodegenerative diseases. Generation of neurons from stem cells could serve as a source for potential cell therapy. This study suggests the potential use of combined selegiline and stem cell therapy to improve deficits in neurodegenerative diseases.

Characterization of canine embryonic stem cell lines derived from different niche microenvironments

Embryo-derived stem cells hold enormous potential for producing cell-based transplantation therapies, allowing high-throughput drug screening and delineating early embryonic development. However, potential clinical applications must first be tested for safety and efficacy in preclinical animal models. Due to physiological and genetic parity to humans, the domestic dog is widely used as a clinically relevant animal model for cardiovascular, neurodegenerative, orthopedic, and oncologic diseases. Therefore, we established numerous putative canine embryonic stem cell (cESC) lines by immunodissection of the inner cell mass (ICM), which we termed OVC.ID.1-23, and by explant outgrowths from whole canine blastocysts, named OVC.EX.1-16. All characterized lines were immunopositive for OCT4, SOX2, NANOG, SSEA-3, and SSEA-4; displayed high telomerase and alkaline phosphatase (ALP) activities; and were maintained in this state up to 37 passages ( approximately 160 days). Colonies from OVC.EX lines showed classic domed hESC-like morphology surrounded by a ring of fibroblast-like cells, whereas all OVC.ID lines exhibited a mixed cell colony of tightly packed cESCs surrounded by a GATA6+/CDX2- hypoblast-derived support layer. Spontaneous serum-only differentiation without feeder layers demonstrated a strong lineage selection associated with the colony niche type, and not the isolation method. Upon differentiation, cESC lines formed embryoid bodies (EB) comprised of cells representative of all germinal layers, and differentiated into cell types of each layer. Canine ESC lines such as these have the potential to identify differences between embryonic stem cell line derivations, and to develop or to test cell-based transplantation therapies in the dog before attempting human clinical trials.

Localization of bone marrow stromal cells in injured spinal cord treated by intravenous route depends on the hemorrhagic lesions in traumatized spinal tissues

OBJECTIVES

Bone marrow stromal cells (BMSCs) have been reported to improve movement deficit in adult rats with spinal cord injury (SCI). The purpose of this study is to determine the distribution of BMSCs in the spinal cord lesion of the contusion model of SCI.

METHODS

Laminectomy was carried out at L1 vertebra level and SCI was carried out using the weight drop method. BMSCs were isolated from adult rats, labeled with bromodeoxyuridine (BrdU) and administered intravenously to the rats 1 week after SCI, which were killed after 4 weeks. The non-treated animals were used as negative control, which showed cavitations of the spinal cord after 5 weeks of SCI. Rats in another group were killed immediately and used to study the hemorrhagic lesions. The volume densities (Vv) of the hemorrhage and cavitation were the highest at the site of direct trauma.

RESULTS

The numerical densities of the transmigrated cells per area (Nat) were as follows: 0.3 +/- 0.2, 3.9 +/- 0.4, 5.4 +/- 0.4, 8.4 +/- 0.5, 5.5 +/- 0.3, 3.6 +/- 0.3 and 0.4 +/- 0.2 at the end and the middle of the thoracic vertebra 13 (T13), the region between T13 and the first lumbar vertebra, the middle of L1, the region between L1 and L2, and the middle and the end of L2 vertebra, respectively. The distribution of Nat at the above regions was a Gaussian model. The volume densities of hemorrhage in the spinal cord taken from the above regions showed that hemorrhage with the highest volume density occurred at the impact site and the volume density declined as the samples taken were more distant from the impact site.

DISCUSSION

The migration of BMSCs in the injured region depends on the amount of the hemorrhage and damage to blood vessels of the spinal cord.

Selegiline Induces Neuronal Phenotype and Neurotrophins Expression in Embryonic Stem Cells

The antiaging effect of selegiline was reported by several investigators; therefore, there is a growing interest in the potential use of stem cell therapy in aging. In this investigation, selegiline was used to induce neuronal differentiation in undifferentiated pluripotent embryonic stem cells (ESCs). The results show that selegiline can induce neuronal phenotype associated with neurotrophic factor expression. Morphologic and immunohistochemical techniques were used to evaluate the differentiation of the CCE cells, Cresyl violet for the morphologic study, anti-synaptophysin and antityrosine hydroxylase antibodies for characterizing the neuronal phenotype of ESCs, and RT-PCR to study the neurotrophins. The results showed that selegiline can induce dose-dependent ESC differentiation into neurons. Moreover, selegiline can induce neurotrophin expression. This study suggests the potential use of combined selegiline and stem cell therapy to improve deficits in neurodegenerative diseases in aging.

Noninvasive imaging of transplanted living functional cells transfected with a reporter estrogen receptor gene

The transplantation of functional cells such as dopaminergic cells into damaged tissue is now clinically ongoing, but at present the population of surviving cells at the transplantation site mostly cannot be noninvasively examined. To visualize surviving transplanted functional cells using a noninvasive method, we chose the estrogen receptor ligand binding domain (ERL) as a reporter molecule and 16alpha-[18F]-fluoro-17beta-estradiol (FES) for its ligand. We used a mouse embryonic stem (ES) cell line for recipient cells as a model. To obtain ES cells that constitutively or inducibly express ERL, we transfected two types of expression vectors into EB5 parental ES cell line using the lipofection method and obtained about 30 clones for each of the two types of transfectants. Then, to examine the expression level of ERL, we performed Western blotting analysis. Ligand uptake experiments were carried out using [3H]-estradiol with or without excessive unlabeled estradiol for control cells and ERL transfectants. Each selected clone was also used for in vivo positron emission tomography (PET) imaging studies involving FES in nude mice transplanted with control cells and ERL transfectants. In some of the clones transfected with the inducible-type ERL gene, protein was expressed much higher than in the controls. However, constitutive-type ERL gene-transfected ES cells showed no protein production in spite of their gene expression activity being considerably high. All clones also expressed equal levels of the Oct-3/4 gene, a marker of pluripotency, in comparison with the parental cells. Also, the specific uptake of [3H]-estradiol was over 30 times higher in inducer-treated ERL-expressing ES cells compared to untreated control cells. Finally, by performing dynamic PET imaging, we successfully visualized ERL-expressing teratomas using FES.

Quantitative screening of embryonic stem cell differentiation: Endoderm formation as a model

Embryonic stem (ES) cells have attracted much attention as a possible source of functional cells for regenerative medicine. Therapeutic use of ES cells requires control over the types and frequencies of cells generated during their in vitro differentiation. Due to the complexity of factors that impact upon ES cell differentiation, novel approaches for the optimization of tissue-specific development are required. This motivates our use of factorial and composite design methods to make empirical investigations more efficient, and to reveal unexpected interactions missed by conventional dose-response analysis. Factorial experiments would benefit from the high content evaluation of a large number of test conditions, necessitating the development of a quantitative screening technology (QST) capable of reporting the absolute number and frequency of target cells. We have developed and validated such a technology for ES cell differentiation analysis using automated fluorescence microscopy, employing endoderm differentiation as a model system. To test this platform, a two-level factorial experiment was carried out to identify major and interactive effects of glucose, insulin, retinoic acid (RA), basic fibroblast growth factor (bFGF), and epidermal growth factor (EGF) on endoderm formation. RA was found to have inhibitory effects on endoderm formation, while low glucose proved beneficial. QST was demonstrated to be a powerful tool to study factors impacting endoderm-specific ES cell differentiation, and should be applicable to the analysis of a range of ES cell-derived tissues.

Insulin production by insulin-producing cells induced from embryonic stem cells

AIM: To study the insulin secretion of insulin-producing cells (IPCs) induced from embryonic stem cells (ESCs).

METHODS: ESCs were allowed to grow on mouse fetal fibroblast feeder layer to keep undifferentiated state, and then transferred into serum-free DMEM supplemented with bFGF to form outgrowths in the culture. At day 21 after induction, the outgrowths were incubated in DTZ solution (final concentration, 100 mg/L) for 15 minutes before being observed microscopically. In addition, insulin production was examined immunohistochemically, and its secretion was determined using ELISA. The gene expression of endocrine pancreatic markers, including PDX-1, insulin1, insulin2 and Glut2, was also analyzed by RT-PCR, and the activity of secreted insulin was determined by glucose-reducing experiment on mice.

RESULTS: ESCs grew and formed embryoid bodies at day 4, and the addition of bFGF promoted the differentiation of ESCs into IPCs. The induced IPCs self-assembled to form three-dimentional clusters, and were stained crimson red by DTZ at day 21 after differentiation. They were found to be immunoreactive to insulin, express pancreatic-duodenal homeobox 1 (PDX1) and insulin2 mRNA. They were also able to secrete detectable amounts of active insulin, which could reduce mouse blood glucose significantly.

CONCLUSION: ES cell-induced IPCs can synthesize and secrete active insulin that is able to reduce blood glucose significantly.

Therapeutic effect of insulin-producing cells induced from embryonic stem cells on diabetic mice

AIM: To study the therapeutic effect on diabetic mice of insulin-producing cells induced from embryonic stem cells.

METHODS: Firstly, ESCs were induced to differentiate in serum-free DMEM supplemented with bFGF for more than 3 weeks, and DTZ staining was used to identify the induced IPCs; Secondly, experimental diabetes was induced in 6- to 8-week-old male Balb/c mice by a single intraperitoneal injection (200 mg/kg) of streptozotocin freshly dissolved in 0.1 moL/L of citrate buffer, pH 4.5; Finally, the induced IPCs were harvested at day 21 after differentiation, and grafted subcutaneously in the shoulder of streptozotocin-diabetic mice to observe their glucose-reducing effect.

RESULTS: ESCs could be induced to differentiate into IPCs in serum-free DMEM supplemented with bFGF. The induced IPCs were stained crimson red by DTZ, and their transplantation could reduce blood glucose of diabetic mouse significantly.

CONCLUSION: ESCs can be induced to differentiate into IPCs in serum-free DMEM supplemented with bFGF, and the induced IPCs transplantation has a certain therapeutic effect on diabetic mice.