Single cell-derived clonally expanded mesenchymal progenitor cells from somatic cell nuclear transfer-derived pluripotent stem cells ameliorate the endometrial function in the uterus of a murine model with Asherman's syndrome.

OBJECTIVES: Because primary mesenchymal progenitor cells (adult-MPCs) have various functions that depend on the tissue origin and donor, de novo MPCs from human pluripotent stem cells (hPSCs) would be required in regenerative medicine. However, the characteristics and function of MPCs derived from reprogrammed hPSCs have not been well studied. Thus, we show that functional MPCs can be successfully established from a single cell-derived clonal expansion following MPC derivation from somatic cell nuclear transfer-derived (SCNT)-hPSCs, and these cells can serve as therapeutic contributors in an animal model of Asherman's syndrome (AS). MATERIALS AND METHODS: We developed single cell-derived clonal expansion following MPC derivation from SCNT-hPSCs to offer a pure population and a higher biological activity. Additionally, we investigated the therapeutic effects of SCNT-hPSC-MPCs in model mice of Asherman's syndrome (AS), which is characterized by synechiae or fibrosis with endometrial injury. RESULTS: Their humoral effects in proliferating host cells encouraged angiogenesis and decreased pro-inflammatory factors via a host-dependent mechanism, resulting in reduction in AS. We also addressed that cellular activities such as the cell proliferation and population doubling of SCNT-hPSC-MPCs resemble those of human embryonic stem cell-derived MPCs (hESC-MPCs) and are much higher than those of adult-MPCs. CONCLUSIONS: Somatic cell nuclear transfer-derived-hPSCs-MPCs could be an advanced therapeutic strategy for specific diseases in the field of regenerative medicine.

Conversion of adult endothelium to immunocompetent haematopoietic stem cells.

Developmental pathways that orchestrate the fleeting transition of endothelial cells into haematopoietic stem cells remain undefined. Here we demonstrate a tractable approach for fully reprogramming adult mouse endothelial cells to haematopoietic stem cells (rEC-HSCs) through transient expression of the transcription-factor-encoding genes Fosb, Gfi1, Runx1, and Spi1 (collectively denoted hereafter as FGRS) and vascular-niche-derived angiocrine factors. The induction phase (days 0-8) of conversion is initiated by expression of FGRS in mature endothelial cells, which results in endogenous Runx1 expression. During the specification phase (days 8-20), RUNX1+ FGRS-transduced endothelial cells commit to a haematopoietic fate, yielding rEC-HSCs that no longer require FGRS expression. The vascular niche drives a robust self-renewal and expansion phase of rEC-HSCs (days 20-28). rEC-HSCs have a transcriptome and long-term self-renewal capacity similar to those of adult haematopoietic stem cells, and can be used for clonal engraftment and serial primary and secondary multi-lineage reconstitution, including antigen-dependent adaptive immune function. Inhibition of TGFß and CXCR7 or activation of BMP and CXCR4 signalling enhanced generation of rEC-HSCs. Pluripotency-independent conversion of endothelial cells into autologous authentic engraftable haematopoietic stem cells could aid treatment of haematological disorders.

Stem cells in genetically-engineered mouse models of prostate cancer.

The cancer stem cell model proposes that tumors have a hierarchical organization in which tumorigenic cells give rise to non-tumorigenic cells, with only a subset of stem-like cells able to propagate the tumor. In the case of prostate cancer, recent analyses of genetically engineered mouse (GEM) models have provided evidence supporting the existence of cancer stem cells in vivo. These studies suggest that cancer stem cells capable of tumor propagation exist at various stages of tumor progression from prostatic intraepithelial neoplasia (PIN) to advanced metastatic and castration-resistant disease. However, studies of stem cells in prostate cancer have been limited by available approaches for evaluating their functional properties in cell culture and transplantation assays. Given the role of the tumor microenvironment and the putative cancer stem cell niche, future studies using GEM models to analyze cancer stem cells in their native tissue microenvironment are likely to be highly informative.

The use of animal models in multiple myeloma.

In myeloma, the understanding of the tissular, cellular and molecular mechanisms of the interactions between tumor plasma cells and bone cells have progressed from in vitro and in vivo studies. However none of the known animal models of myeloma reproduce exactly the human form of the disease. There are currently three types of animal models: (1) injection of pristane oil in BALB/c mice leads to intraperitoneal plasmacytomas but without bone marrow colonization and osteolysis; (2) injection of malignant plasma cell lines in immunodeficient mice SCID or NOD/SCID; the use of the SCID-hu or SCID-rab model allows the use of fresh plasma cells obtained from MM patients; (3) injection of allogeneic malignant plasma cells (5T2MM, 5T33) in the C57BL/KalwRij mouse induces bone marrow proliferation and osteolytic lesions. These cells did not grow in vitro and can be propagated by injection of plasma cells isolated from bone marrow of a mouse at end stage of the disease into young recipient mice. The 5TGM1 is a subclone of 5T33MM cells and can grow in vitro. Among the different models, the 5TMM models and SCID-hu/SCID-rab models were extensively used to test pathophysiological hypotheses and to assess anti-osteoclastic, anti-osteoblastic or anti-tumor therapies in myeloma. In the present review, we report the different types of animal models of MM and describe their interests and limitations.

Isolation and characterization of a spontaneously immortalized multipotent mesenchymal cell line derived from mouse subcutaneous adipose tissue.

The emerging field of tissue engineering and regenerative medicine is a multidisciplinary science that is based on the combination of a reliable source of stem cells, biomaterial scaffolds, and cytokine growth factors. Adult mesenchymal stem cells are considered important cells for applications in this field, and adipose tissue has revealed to be an excellent source of them. Indeed, adipose-derived stem cells (ASCs) can be easily isolated from the stromal vascular fraction (SVF) of adipose tissue. During the isolation and propagation of murine ASCs, we observed the appearance of a spontaneously immortalized cell clone, named m17.ASC. This clone has been propagated for more than 180 passages and stably expresses a variety of stemness markers, such as Sca-1, c-kit/CD117, CD44, CD106, islet-1, nestin, and nucleostemin. Furthermore, these cells can be induced to differentiate toward osteogenic, chondrogenic, adipogenic, and cardiogenic phenotypes. m17.ASC clone displays a normal karyotype and stable telomeres; it neither proliferates when plated in soft agar nor gives rise to tumors when injected subcutaneously in NOD/SCID-γ (null) mice. The analysis of gene expression highlighted transcriptional traits of SVF cells. m17.ASCs were genetically modified by lentiviral vectors carrying green fluorescent protein (GFP) as a marker transgene and efficiently engrafted in the liver, when injected in the spleen of NOD/SCID-γ (null) monocrotaline-treated mice. These results suggest that this non-tumorigenic spontaneously immortalized ASC line may represent a useful tool (cell model) for studying the differentiation mechanisms involved in tissue repair as well as a model for pharmacological/toxicological studies.

CD8+ T-cell clones specific for the 5T4 antigen target renal cell carcinoma tumor-initiating cells in a murine xenograft model.

The tumor antigen 5T4 is frequently expressed at high levels on renal cell carcinoma (RCC) and other epithelial carcinomas. Surveys of normal tissues demonstrate abundant 5T4 expression on placental trophoblast cells with limited expression elsewhere. 5T4 is the target for a therapeutic cancer vaccine (MVA-5T4) that elicits 5T4-specific serological, proliferative, and cytotoxic T lymphocyte (CTL) responses. However, the antitumor activity of 5T4-specific CTL has not been extensively characterized. CD8 T cells from HLA-A2 healthy donors (n=4) or RCC patients (n=2) were stimulated in vitro with the HLA-A2-binding nonamer peptides 5T417-25 or 5T497-105 and screened by flow cytometry with specific tetramers (TET). CD8/TET T-cell clones specific for 5T417-25 or 5T497-105 peptide were isolated from 4/6 and 1/4 donors, respectively. A subset of clones specific for 5T417-25 was cytolytic for MVA-5T4-infected HLA-A2 EBV-transformed lymphoblastoid cell line target cells and for constitutively HLA-A2-expressing and 5T4-expressing RCC tumor cell lines (including A498 RCC). In a xenoengraftment assay, the coinoculation of a representative 5T417-25-specific CTL clone with A498 RCC tumors cells into immune-deficient mice completely prevented growth of A498 tumors. Taken together, these data demonstrate high-avidity CD8 CTL able to recognize the naturally processed 5T417-25 epitope on RCC tumor cells including putative tumor-initiating cells are present in peripheral blood of both healthy donors and RCC patients. CD8T-cell immunity targeting 5T417-25 is therefore of substantial interest both as a potential target for further development of vaccination or adoptive cellular immunotherapy and for immune monitoring studies in association with nonspecific immunotherapies.

Comparative analysis of steroid sensitivity of T helper cells in vitro and in vivo.

BACKGROUND: Glucocorticoid (GC) action on asthma has been partly explained by the inhibition of T cell activation. We analyzed the steroid sensitivity of ovalbumin (OVA) reactive helper T (Th) cell clones both in vitro and in vivo. METHOD: For in vitro experiments, Th clones were cultured with antigen-presenting cells, OVA, and various concentrations of dexamethasone (DEX). The proliferative response of each Th clone was measured by (3)H-thymidine uptake. For in vivo experiments, unprimed BALB/c mice were transferred with Th clones, challenged with OVA, and administered DEX subcutaneously. The number of infiltrating cells in bronchoalveolar lavage fluid (BALF) was measured. RESULTS: Six Th clones were classified as steroid-sensitive or steroid-resistant clones in terms of the effects of GC on the proliferative responses analyzedin vitro. Airway infiltration of eosinophils and lymphocytes of mice transferred with steroid-sensitive clones were effectively inhibited by the administration of DEX. In contrast, those of mice transferred with steroid-resistant clones were not significantly inhibited by DEX; the number of eosinophils in the BALF of mice transferred with 1 steroid-resistant clone, i.e. T5-1, was only partially reduced. CONCLUSION: The steroid sensitivity of Th clones measured in vitro was consistent with that of an adoptively transferred asthma model measuredin vivo. Steroid-sensitive and resistant asthma models seem valuable for understanding the mechanisms of steroid resistance in severe asthma.

Cancer stem cells in squamous cell carcinoma switch between two distinct phenotypes that are preferentially migratory or proliferative.

Epithelial-to-mesenchymal transition (EMT) is an important driver of tumor invasion and metastasis, which causes many cancer deaths. Cancer stem cells (CSC) that maintain and initiate tumors have also been implicated in invasion and metastasis, but whether EMT is an important contributor to CSC function is unclear. In this study, we investigated whether a population of CSCs that have undergone EMT (EMT CSCs) exists in squamous cell carcinoma (SCC). We also determined whether a separate population of CSCs that retain epithelial characteristics (non-EMT CSCs) is also present. Our studies revealed that self-renewing CSCs in SCC include two biologically-distinct phenotypes. One phenotype, termed CD44(high)ESA(high), was proliferative and retained epithelial characteristics (non-EMT CSCs), whereas the other phenotype, termed CD44(high)ESA(low), was migratory and had mesenchymal traits characteristic of EMT CSCs. We found that non-EMT and EMT CSCs could switch their epithelial or mesenchymal traits to reconstitute the cellular heterogeneity which was characteristic of CSCs. However, the ability of EMT CSCs to switch to non-EMT character was restricted to cells that were also ALDH1(+), implying that only ALDH1(+) EMT cells had the ability to seed a new epithelial tumor. Taken together, our findings highlight the identification of two distinct CSC phenotypes and suggest a need to define therapeutic targets that can eradicate both of these variants to achieve effective SCC treatment.

HIV-specific CD8+ T cells from HIV+ individuals receiving HAART can be expanded ex vivo to augment systemic and mucosal immunity in vivo.

Most HIV+ individuals require lifelong highly active antiretroviral therapy (HAART) to suppress HIV replication, but fail to eliminate the virus in part because of residual replication in gut-associated lymphoid tissues (GALT). Naturally elicited HIV-specific CD8+ T cells generated in the acute and chronic infectious phases exhibit antiviral activity, but decrease in number after HAART. Therapeutic vaccines represent a potential strategy to expand cellular responses, although previous efforts have been largely unsuccessful, conceivably because of a lack of responding HIV-specific central-memory CD8+ T cells (Tcm). To determine whether patients receiving HAART possess CD8+ T cells with Tcm qualities that are amenable to augmentation, HIV-specific CD8+ T-cell clones were derived from HIV-reactive CD28+CD8+ T-cell lines isolated from 7 HIV+ HAART-treated patients, expanded ex vivo, and reinfused into their autologous host. Tracking of the cells in vivo revealed that clones could persist for ≥ 84 days, maintain expression and/or re-express CD28, up-regulate CD62L, secrete IL-2, proliferate on cognate Ag encounter and localize to the rectal mucosa. These results suggest some infused cells exhibited phenotypic and functional characteristics shared with Tcm in vivo, and imply that more effective therapeutic vaccination strategies targeting CD8+ Tcm in patients on HAART might provide hosts with expanded, long-lasting immune responses not only systemically but also in GALT.

Stem cells isolated from human dental follicles have osteogenic potential.

OBJECTIVE: Stem cells isolated from human dental follicles as a potential cell source for bone-tissue engineering were examined for correcting a critical bone defect. STUDY DESIGN: Impacted third molars were collected and single cell-derived cell populations were cultivated in growth medium. Single cell-derived cell lines were examined in terms of cell shape, gene expression patterns, differentiation capacity in vitro, and osteogenic potential in vivo. RESULTS: Three distinct cell populations were identified with different morphologies, patterns of gene expression, and differentiation capacity. All 3 cell populations promoted bone formation when transplanted into surgically created critical-size defects in immunodeficient rat calvaria, compared with control animals without cell transplantation, although one of these populations showed a weak capacity for osteogenetic differentiation in vitro. CONCLUSIONS: Human dental follicle can derive at least 3 unique cell populations in culture, all of which promote bone formation in vivo.

Intracerebellar transplantation of neural stem cells into mice with neurodegeneration improves neuronal networks with functional synaptic transmission.

Recent studies have shown that many kinds of stem cells are beneficial for patients suffering with neurodegenerative diseases. We investigated the effects of neural stem cell (NSC), Maudsley hippocampal clone 36 (MHP36) in the Niemann-Pick disease type C (NP-C) model mice. Herein, we demonstrate that MHP36 transplantation improves the neuropathological features without acute immune response and promotes neuronal networks with functional synaptic transmission. The number of surviving Purkinje neurons substantially increased in MHP36 transplanted NP-C mice compared with sham-transplanted NP-C mice. MHP36 significantly reduced both of astrocytic and microglial activations. We also found that these surviving Purkinje neurons have normal functional synapses with parallel fibers that have normal glutamate release probability in MHP36 transplanted NP-C mice. Furthermore, real-time PCR analysis revealed up-regulation of genes involved in both excitatory and inhibitory neurotransmission encoding subunits of the ionotropic glutamate receptors GluR2, 3 and GABAA receptor beta2. These findings suggest that NSC, MHP36 transplantation may have therapeutic effects in the treatment of NP-C and other neurodegenerative diseases.

Functional mesenchymal stem cells derived from human induced pluripotent stem cells attenuate limb ischemia in mice.

BACKGROUND: Aging and aging-related disorders impair the survival and differentiation potential of bone marrow mesenchymal stem cells (MSCs) and limit their therapeutic efficacy. Induced pluripotent stem cells (iPSCs) may provide an alternative source of functional MSCs for tissue repair. This study aimed to generate and characterize human iPSC-derived MSCs and to investigate their biological function for the treatment of limb ischemia. METHODS AND RESULTS: Human iPSCs were induced to MSC differentiation with a clinically compliant protocol. Three monoclonal, karyotypically stable, and functional MSC-like cultures were successfully isolated using a combination of CD24(-) and CD105(+) sorting. They did not express pluripotent-associated markers but displayed MSC surface antigens and differentiated into adipocytes, osteocytes, and chondrocytes. Transplanting iPSC-MSCs into mice significantly attenuated severe hind-limb ischemia and promoted vascular and muscle regeneration. The benefits of iPSC-MSCs on limb ischemia were superior to those of adult bone marrow MSCs. The greater potential of iPSC-MSCs may be attributable to their superior survival and engraftment after transplantation to induce vascular and muscle regeneration via direct de novo differentiation and paracrine mechanisms. CONCLUSIONS: Functional MSCs can be clonally generated, beginning at a single-cell level, from human iPSCs. Patient-specific iPSC-MSCs can be prepared as an "off-the-shelf" format for the treatment of tissue ischemia.

Migration and differentiation of neural cell lines transplanted into mouse brains.

In the past few years, the plasticity of the regional specification of the CNS has been widely debated on the results from in utero transplantation. Two different results are reported with this transplantation method. One is that the distribution of transplanted cells is dependent on the donor origin, and the other is that the distribution is independent on the donor cell origin. The present study attempted to examine closely the plasticity of the regional specification by in utero transplantation method with clonal neural cell lines, 2Y-3t and 2Y-5o2b. These lines were established from a cerebellum of an adult p53-deficient mouse. Our results showed that transplanted cells migrated into various regions of the CNS and supported the independent distribution. Moreover, different distribution patterns of transplanted cells were observed between host sexes. Labeled cells were localized around the ventricle of neonatal host brains, where they were undifferentiated. In 2-3 weeks after birth, labeled cells were found in the brain parenchyma and some of them took neuronal morphology. In the rostral migratory stream (RMS), cells with unipolar or bipolar morphology were still undifferentiated. In other regions, labeled cells were often associated with blood vessels; the soma were on the surface of vessels, extending processes or neurites into surrounding brain parenchyma. Time-lapse imaging demonstrated that they were migrating with blood vessels.

Inhibition of skeletal metastasis by ectopic ERalpha expression in ERalpha-negative human breast cancer cell lines.

Some hormone-independent breast cancers lack functional estrogen receptors (ERs) and show evidence of a more aggressive metastatic phenotype. A protective role of the ER has also been suggested in hormone-resistant breast cancer progression. In this study, we have investigated the effect of the ectopic expression of human ERalpha on the bone-metastatic potential of highly metastatic ERalpha-negative human breast cancer MDA-MB-231 and MDA-MB-435-F-L cell lines in an experimental model of bone metastasis in nude mice. ERalpha overexpression had no effect on the growth of both cell lines but reduced the expression of integrin alpha(v)beta(3) and the receptor activator of NF-kappaB, which are known to promote bone metastasis. A significant reduction in the incidence of osteolytic bone metastasis was observed by X-ray imaging of the legs and arms of mice inoculated with ERalpha-expressing clones of MDA-MB-231 cells in comparison to controls. Ectopic expression of ERalpha in MDA-MB-435-F-L cells also reduced their widespread skeletal metastasis to the legs, arms, spine, and mandible, as detected by whole-mouse enhanced green fluorescent protein imaging. Our study indicates for the first time that stable reintroduction of functional ERalpha in ERalpha-negative human breast cancer cells can inhibit their aggressive bone-metastatic potential in an experimental bone metastasis model.

Mathematical modelling of aerosolised skin grafts incorporating keratinocyte clonal subtypes.

Severe burns can be very traumatic for the patient, and while burns caused by industrial or domestic accidents are common, there are also increasing numbers of burns associated with terrorism. A novel technique to assist in the healing process is to spray skin cells, keratinocytes, that are cultured from the patient's own tissue, directly onto the burn site. This process involves taking some undamaged skin from the patient, allowing the skin cells to proliferate rapidly in the laboratory over a period of 5-10 days, harvesting and separating the cells and then spraying them onto the burn. This paper deals with keratinocytes that have been cultured in vitro for a short period of time (early passage cultured cells). The spraying process has yet to be optimised with respect to the seeding density required for fastest re-epithelisation and thus there is a need for this process to be modelled. In this paper, we review some of the skin biology and develop a mathematical model of the growth patterns of cell colonies after they have been applied using a aerosolised technique. The model allows us to predict coverage over time and can be used as a decision support tool for clinicians.

Stem cell research: cloning, therapy and scientific fraud.

Stem cell research has generated intense excitement, awareness, and debate. Events in the 2005-2006 saw the rise and fall of a South Korean scientist who had claimed to be the first to clone a human embryonic stem cell line. From celebration of the potential use of stem cells in the treatment of human disease to disciplinary action taken against the disgraced scientists, the drama has unfolded throughout the world media. Prompted by an image of therapeutic cloning presented on a South Korean stamp, a brief review of stem cell research and the events of the Woo-suk Hwang scandal are discussed.

Evidence of donor-derived hematologic malignancies after hematopoietic stem cell transplantation.

Increasing the upper age limit for recipients of hematopoietic stem cell transplantation (HCT) naturally has also increased the age of the corresponding related donor population. Because aging is a risk factor for malignancies, the risk of transferring preexisting malignant or premalignant hemopoietic clones in the process of HCT might be expected to increase as well. Anecdotal clinical cases of malignancies derived from donor cells in patients undergoing HCT have been published since 1971. In this article, we report 12 new cases that fit 2 different categories: (1) cases in which clones with characteristics of lymphohemopoietic malignancies were transferred from the donors to the recipients and (2) cases in which the malignant clone evolved from healthy donor cells once transplanted into the recipient. Donors in the first group were significantly older than donors in the second group. A more systematic examination of the prevalence and biology of donor malignancies would merit study.