Cynomolgus Embryonic Stem Research Articles

New monkey embryo models-it's getting complicated.

Li etal.1 report on the generation of cynomolgus monkey models of blastocyst-stage embryos (called "blastoids") using naive cynomolgus embryonic stem cells. These blastoids recapitulate gastrulation invitro and induce early pregnancy responses when transferred into cynomolgus monkey surrogates, prompting consideration of the policy implications for human blastoid research.

Induction of Pluripotent Stem Cells from a Cynomolgus Monkey Using a Polycistronic Simian Immunodeficiency Virus–Based Vector, Differentiation Toward Functional Cardiomyocytes, and Generation of Stably Expressing Reporter Lines

Induced pluripotent stem cells (iPSCs) represent a novel cell source for regenerative therapies. Many emerging iPSC-based therapeutic concepts will require preclinical evaluation in suitable large animal models. Among the large animal species frequently used in preclinical efficacy and safety studies, macaques show the highest similarities to humans at physiological, cellular, and molecular levels. We have generated iPSCs from cynomolgus monkeys (Macaca fascicularis) as a segue to regenerative therapy model development in this species. Because typical human immunodeficiency virus type 1 (HIV-1)-based lentiviral vectors show poor transduction of simian cells, a simian immunodeficiency virus (SIV)-based vector was chosen for efficient transduction of cynomolgus skin fibroblasts. A corresponding polycistronic vector with codon-optimized reprogramming factors was constructed for reprogramming. Growth characteristics as well as cell and colony morphology of the resulting cynomolgus iPSCs (cyiPSCs) were demonstrated to be almost identical to cynomolgus embryonic stem cells (cyESCs), and cyiPSCs expressed typical pluripotency markers including OCT4, SOX2, and NANOG. Furthermore, differentiation in vivo and in vitro into derivatives of all three germ layers, as well as generation of functional cardiomyocytes, could be demonstrated. Finally, a highly efficient technique for generation of transgenic cyiPSC clones with stable reporter expression in undifferentiated cells as well as differentiated transgenic cyiPSC progeny was developed to enable cell tracking in recipient animals. In conclusion, our data indicate that cyiPSCs represent a valuable cell source for establishment of macaque-based allogeneic and autologous preclinical cell transplantation models for various fields of regenerative medicine.

Maternal administration of busulfan before in utero transplantation of human hematopoietic stem cells enhances engraftments in sheep

In utero transplantation (IUT) of human hematopoietic stem cells has been conducted in sheep, which are used as large animal models of human hematopoietic reconstitution and models for clinical IUT; however, the levels of engraftment have generally been low. Busulfan (BU), a myeloablative agent, is often administered to patients before hematopoietic stem cells transplantation to improve the engraftment. In this study, hematopoietic activity was evaluated in adult sheep after administering BU at different doses. Next, pregnant ewes were administered BU, and dams as well as their fetuses were evaluated, as BU readily crosses the sheep placenta. Then, the BU dose with the desired outcomes was selected and administered to pregnant ewes at 2 or 6 days before performing IUT using human cord blood CD34(+) cells. The engraftment was evaluated in recipients that underwent IUT in the presence or absence of BU. As a result, hematopoietic activity was safely and transiently suppressed in adult sheep treated with 5 to 7.5 mg/kg BU. BU crossed the sheep placenta, and fetal sheep were indeed conditioned by administering 3 mg/kg BU to pregnant ewes. Engraftment of human CD34(+) cells in fetal recipients was enhanced when IUT was carried out 6 days post-BU. Up to 3.3% engraftment levels (in terms of bone marrow colony-forming units) were achieved with the IUT of 0.72 to 2.4 million CD34(+) cells when BU was used. BU can be administered to pregnant ewes to effectively condition the fetal recipient for IUT with enhanced engraftment of donor cells.

Induction of Retinal Pigment Epithelial Cells from Monkey iPS Cells

The induced pluripotent stem (iPS) cell is expected to be a powerful tool for research and development in regenerative medicine. Previously, the authors reported that human iPS cells differentiated into retinal cells, including photoreceptors and retinal pigment epithelial cells. In this study, they produced iPS cell lines from monkeys to investigate their ability to differentiate into retinal cells. To generate iPS cells, the fibroblasts derived from cynomolgus monkey abdominal skin were infected with retroviruses carrying Oct3/4, Sox2, Klf4, and c-Myc genes and then were cultured on STO feeder cells. Next, the established iPS cells were cultured with the conditioned medium of PA6 cells to induce RPE cells. The properties of the differentiated RPE cells were analyzed. Approximately 1 month after viral infection, some epithelial-like colonies appeared among the fibroblasts. These colonies were morphologically similar to the cynomolgus embryonic stem (ES) cell and expressed ES cell-specific markers. By producing teratomas in SCID mice, these cells were confirmed to have the ability to differentiate into three germ layers. In addition, the RPE cells induced from the monkey iPS cells had characteristic polygonal shapes and pigments. These cells expressed RPE cell-specific markers such as RPE65, CRALBP, Bestrophin 1, and MERTK and exhibited phagocytotic function in vitro. The RPE cells derived from monkey skin with iPS cell technology can be used for autologous or allogeneic transplantation to test the possibility of immune rejection and to evaluate their function in vivo with the same techniques that will be used in clinical trials.

Super selective neuronal differentiation of cynomolgus embryonic stem cells and plasticity of induced neural system

Super selective neuronal differentiation of cynomolgus embryonic stem cells and plasticity of induced neural system

Reality and problems of super selective neuronal differentiation of cynomolgus embryonic stem cells

Reality and problems of super selective neuronal differentiation of cynomolgus embryonic stem cells

ERas is Expressed in Primate Embryonic Stem Cells but not Related to Tumorigenesis

The ERas gene promotes the proliferation of and formation of teratomas by mouse embryonic stem (ES) cells. However, its human orthologue is not expressed in human ES cells. This implies that the behavior of transplanted mouse ES cells would not accurately reflect the behavior of transplanted human ES cells and that the use of nonhuman primate models might be more appropriate to demonstrate the safety of human ES cell-based therapies. However, the expression of the ERas gene has not been examined in nonhuman primate ES cells. In this study, we cloned the cynomolgus homologue and showed that the ERas gene is expressed in cynomolgus ES cells. Notably, it is also expressed in cynomolgus ES cell-derived differentiated progeny as well as cynomolgus adult tissues. The ERas protein is detectable in various cynomolgus tissues as assessed by immunohistochemisty. Cynomolgus ES cell-derived teratoma cells, which also expressed the ERas gene at higher levels than the undifferentiated cynomolgus ES cells, did not develop tumors in NOD/Shi-scid, IL-2Rgamma(null) (NOG) mice. Even when the ERas gene was overexpressed in cynomolgus stromal cells, only the plating efficiency was improved and the proliferation was not promoted. Thus, it is unlikely that ERas contributes to the tumorigenicity of cynomolgus cells. Therefore, cynomolgus ES cells are more similar to human than mouse ES cells despite that ERas is expressed in cynomolgus and mouse ES cells but not in human ES cells.

Multitracer assessment of dopamine function after transplantation of embryonic stem cell‐derived neural stem cells in a primate model of Parkinson's disease

The ability of primate embryonic stem (ES) cells to differentiate into dopamine (DA)-synthesizing neurons has raised hopes of creating novel cell therapies for Parkinson's disease (PD). As the primary purpose of cell transplantation in PD is restoration of dopaminergic neurotransmission in the striatum, in vivo assessment of DA function after grafting is necessary to achieve better therapeutic effects. A chronic model of PD was produced in two cynomolgus monkeys (M-1 and M-2) by systemic administration of neurotoxin. Neural stem cells (NSCs) derived from cynomolgus ES cells were implanted unilaterally in the putamen. To evaluate DA-specific functions, we used multiple [(11)C]-labeled positron emission tomography (PET) tracers, including [beta-(11)C]L-3,4-dihydroxyphenylalanine (L-[beta-(11)C]DOPA, DA precursor ligand), [(11)C]-2beta-carbomethoxy-3beta-(4-fluorophenyl)tropane ([(11)C]beta-CFT, DA transporter ligand) and [(11)C]raclopride (D(2) receptor ligand). At 12 weeks after grafting NSCs, PET demonstrated significantly increased uptake of L-[beta-(11)C]DOPA (M-1:41%, M-2:61%) and [(11)C]beta-CFT (M-1:31%, M-2:36%) uptake in the grafted putamen. In addition, methamphetamine challenge in M-2 induced reduced [(11)C]raclopride binding (16%) in the transplanted putamen, suggesting release of DA. These results show that transplantation of NSCs derived from cynomolgus monkey ES cells can restore DA function in the putamen of a primate model of PD. PET with multitracers is useful for functional studies in developing cell-based therapies against PD.

Limitation and development of super selective neuronal differentiation of cynomolgus embryonic stem cells

Limitation and development of super selective neuronal differentiation of cynomolgus embryonic stem cells

Variation in the Incidence of Teratomas after the Transplantation of Nonhuman Primate ES Cells into Immunodeficient Mice.

Embryonic stem (ES) cells have the ability to generate teratomas when transplanted into immunodeficient mice, but conditions affecting the generation remain to be elucidated. Nonhuman primate cynomolgus ES cells were transplanted into immunodeficient mice under different conditions; the number of transplanted cells, physical state (clumps or single dissociated cells), transplant site, differentiation state, and immunological state of recipient mice were all varied. The tumorigenicity was then evaluated. When cynomolgus ES cells were transplanted as clumps into the lower limb muscle in either nonobese diabetic/severe combined immunodeficiency (NOD/SCID) or NOD/SCID/?cnull (NOG) mice, teratomas developed in all the animals transplanted with 1 × 105 or more cells, but were not observed in any mouse transplanted with 1 × 103 cells. However, when the cells were transplanted as dissociated cells, the number of cells necessary for teratomas to form in all mice increased to 5 × 105. When the clump cells were injected subcutaneously (instead of intramuscularly), the number also increased to 5 × 105. When cynomolgus ES cell-derived progenitor cells (1 × 106), which included residual pluripotent cells, were transplanted into the lower limb muscle of NOG or NOD/SCID mice, the incidence of teratomas differed between the strains; teratomas developed in five of five NOG mice but in only two of five NOD/SCID mice. The incidence of teratomas varied substantially depending on the transplanted cells and recipient mice. Thus, considerable care must be taken as to tumorigenicity.

Knockout Serum Replacement (KSR) Has a Suppressive Effect on Sendai Virus-Mediated Transduction of Cynomolgus ES Cells

Sendai virus (SeV) vectors can introduce foreign genes efficiently and stably into primate embryonic stem (ES) cells. For the application of these cells, the control of transgene expression is important. Cynomolgus ES cells transduced with a SeV vector expressing the green fluorescent protein (GFP) gene were propagated in Knockout serum replacement (KSR)-supplemented medium, used widely for the serum-free culture of ES cells, and growth and transgene expression were evaluated. The SeV vector-mediated GFP expression was suppressed in the KSR-supplemented medium, although it was stable in regular fetal bovine serum (FBS)-supplemented medium. Propagation in the KSR-supplemented medium eventually resulted in a complete suppression of GFP expression and eradication of the SeV genome. The inhibitory effect of KSR on the transduction was attributable to the positive selection of untransduced ES cells in addition to the removal of the SeV vector from transduced cells. KSR also reduced the efficiency of the transduction. SeV vector-mediated transgene expression in ES cells was suppressed in the KSR-supplemented medium. Although the suppression is limited in specified cells such as ES cells, these findings will help elucidate how to control transgene expression.

Sustained Macroscopic Engraftment of Cynomolgus Embryonic Stem Cells In Xenogeneic Large Animals After In Utero Transplantation

Because embryonic stem (ES) cells are able to proliferate indefinitely and differentiate into any type of cell, they have the potential for providing an inexhaustible supply of transplantable cells or tissues. However, methods for the in vitro differentiation of human ES cells are still quite limited. One possible strategy would be to generate differentiated cells in vivo. In view of future clinical application, we investigated the possibility of using xenogeneic large animals for this purpose. We transplanted nonhuman primate cynomolgus ES cells into fetal sheep at 43-67 gestational days (full term 147 days, n=15). After birth, cynomolgus tissues, which were mature teratomas, had been engrafted in sheep when more than 1 x 10(6) ES cells were transplanted at <50 gestational days. Despite the sustained engraftment, both cellular and humoral immune responses against the ES cells were detected, and additional transplantation was not successful in the animals. At 2 weeks post-transplantation, the ES cell progeny proliferated when transplanted at 48 (<50) gestational days, whereas they were cleared away when transplanted at 60 (>50) gestational days. These results support the rapid development of the xenogeneic immunological barrier in fetal sheep after 50 gestational days. Notably, a large number of Foxp3(+) regulatory T cells were present around the ES cell progeny, but macrophages were absent when the transplant was conducted at <50 gestational days, implying that regulatory T cells and premature innate immunity might have contributed to the sustained engraftment. In conclusion, long-term macroscopic engraftment of primate ES cells in sheep is feasible despite the xenogeneic immunological barrier.

Super selective neuronal differentiation and application of cynomolgus embryonic stem cells

Super selective neuronal differentiation and application of cynomolgus embryonic stem cells

Hematopoietic Microchimerism in Sheep After In Utero Transplantation of Cultured Cynomolgus Embryonic Stem Cells

Although directed differentiation of human embryonic stem (ES) cells would enable a ready supply of cells and tissues required for transplantation therapy, the methodology is limited. We have developed a novel method for hematopoietic development from primate ES cells. We first cultured cynomolgus monkey ES cells in vitro and transplanted the cells in vivo into fetal sheep liver, generating sheep with cynomolgus hematopoiesis. Cynomolgus ES cells were induced to mesodermal cells on murine stromal OP9 cells with multiple cytokines for 6 days. The cells (average 4.8 x 10 cells) were transplanted into fetal sheep in the liver (n=4) after the first trimester (day 55-73, full term 147 days). The animals were delivered at full term, and two of them were intraperitoneally administered with human stem-cell factor (SCF). Cynomolgus hematopoietic progenitor cells were detected in bone marrow at a level of 1% to 2% in all four sheep up to 17 months posttransplant. No teratoma was found in the lambs. After SCF administration, the fractions of cynomolgus hematopoiesis increased by several-fold (up to 13%). Cynomolgus cells were also detected in the circulation, albeit at low levels (<0.1%). Long-term hematopoietic microchimerism from primate ES cells was observed after in vitro differentiation to mesodermal cells, followed by in vivo introduction into the fetal liver microenvironment. The mechanism of such directed differentiation of ES cells remains to be elucidated, but this procedure should allow further investigation.

Efficient Gene Transfer into Primate ES Cells and Stable Transgene Expression during Hematopoietic Differentiation by Sendai Virus Vector.

Since human embryonic stem (ES) cell lines have the ability to both proliferate indefinitely and differentiate into multiple tissue cells, they are expected to have clinical applications as well as to serve as models for basic research and drug development. Although efficient and stable gene transfer into primate ES cells would be useful for such purposes, it has been difficult and only lentiviral vectors have been successful in achieving it. We have previously developed Sendai virus (SeV) vector that is capable of self-replication but incapable of transmitting to other cells. The vector replicates in the form of negative-sense single-stranded RNA in the cytoplasm of infected cells and does not go through a DNA phase. SeV vector can efficiently introduce foreign genes without toxicity into various types of cells including hematopoietic progenitor cells. In this study, we have examined the efficacy of SeV vector to introduce a new genetic material into nonhuman primate cynomolgus ES cells.Cynomolgus ES cells were once exposed to a SeV vector carrying the GFP gene (50 TU/ml). About 60% of cells stably fluoresced at least for a month as assessed by flow cytometry. Fluorescent ES-cell colonies were plucked under a fluorescent microscope once at one month after infection and they were propagated. The GFP gene was then vigorously and stably expressed in about 90% of the cells for a year. The undifferentiated cell fractions were unchanged after the SeV infection of ES cells as assessed by staining with alkaline phosphatase and SSEA-4. In addition, the infected, fluorescent ES cells were able to form fluorescent teratomas when transplanted into immunodeficient mice. Thus, the SeV infection did not hamper pluripotency of ES cells and transgene silencing did not occur during the teratoma formation in vivo. For induction of hematopoietic differentiation, the infected, fluorescent ES cells were seeded onto OP9 stromal cells in the presence of multiple cytokines including BMP-4 and VEGF. Cells at day 18 were subjected to clonogenic hematopoietic colony formation assays. Resulting colonies at day 14 fluoresced and the colonies contained NBT-positive, fluorescent mature granulocytes. Thus, SeV-mediated transgene was stably expressed even after the terminal differentiation to granulocytes. In addition, SeV-mediated GFP expression levels in ES cells could be reduced dose-dependently by the addition of an anti-RNA virus drug, ribavirin, to the culture. Upon discontinuation of ribavirin treatment, the cells regained the original level of GFP expression. Ribavirin is an inhibitor of viral RNA polymerase and used for treatment of hepatitis C infection. In conclusion, SeV vector will be a useful tool for gene transfer into primate ES cells and the method of using anti-viral drugs should allow further investigation for regulated SeV-mediated gene expression.

Efficient and stable Sendai virus-mediated gene transfer into primate embryonic stem cells with pluripotency preserved.

Efficient gene transfer and regulated transgene expression in primate embryonic stem (ES) cells are highly desirable for future applications of the cells. In the present study, we have examined using the nonintegrating Sendai virus (SeV) vector to introduce the green fluorescent protein (GFP) gene into non-human primate cynomolgus ES cells. The GFP gene was vigorously and stably expressed in the cynomolgus ES cells for a year. The cells were able to form fluorescent teratomas when transplanted into immunodeficient mice. They were also able to differentiate into fluorescent embryoid bodies, neurons, and mature blood cells. In addition, the GFP expression levels were reduced dose-dependently by the addition of an anti-RNA virus drug, ribavirin, to the culture. Thus, SeV vector will be a useful tool for efficient gene transfer into primate ES cells and the method of using antiviral drugs should allow further investigation for regulated SeV-mediated gene expression.

047 Allogeneic Transplantation of Genetically Modified Primate Embryonic Stem Cells

Aim: To examine the efficacy and safety of human embryonic stem (ES) cell‐based therapies, allogeneic transplantation of monkey ES cells would be useful. We transplanted genetically marked monkey ES cells into the allogeneic fetus. Methods and Results: Cynomolgus ES cells were transduced once using a simian immunodeficiency virus‐based lentivirus vector encoding the GFP gene driven by the CMV promoter at 1, 10 and 100 transducing units per cell. Five days posttransduction, 60, 80 and 90% of the cells expressed GFP, respectively, and the expression levels were stable for 5 months. GFP expression was still observed after embryoid‐body formation. The gene‐marked ES cells were transplanted into the cynomolgus fetus in the abdominal cavity (n = 2) or liver (n = 1) after the first trimester. The fetuses were delivered 1 month posttransplantation. Transplanted cell progeny were detected (∼1%) in multiple tissues by quantitative PCR and in situ PCR of the GFP sequence. No teratoma was found in the tissues. Conclusions: Cynomolgus ES cells can be engrafted in the allogeneic fetus. We are now trying to transplant cynomolgus ES cells differentiated to neural or hematopoietic lineage.

Engraftment and tumor formation after allogeneic in utero transplantation of primate embryonic stem cells.

To achieve human embryonic stem (ES) cell-based transplantation therapies, allogeneic transplantation models of nonhuman primates would be useful. We have prepared cynomolgus ES cells genetically marked with the green fluorescent protein (GFP). The cells were transplanted into the allogeneic fetus, taking advantage of the fact that the fetus is so immunologically immature as not to induce immune responses to transplanted cells and that fetal tissue compartments are rapidly expanding and thus providing space for the engraftment. Cynomolgus ES cells were genetically modified to express the GFP gene using a simian immunodeficiency viral vector or electroporation. These cells were transplanted in utero with ultrasound guidance into the cynomolgus fetus in the abdominal cavity (n=2) or liver (n=2) at the end of the first trimester. Three fetuses were delivered 1 month after transplantation, and the other, 3 months after transplantation. Fetal tissues were examined for transplanted cell progeny by quantitative polymerase chain reaction and in situ polymerase chain reaction of the GFP sequence. A fluorescent tumor, obviously derived from transplanted ES cells, was found in the thoracic cavity at 3 months after transplantation in one fetus. However, transplanted cell progeny were also detected (approximately 1%) without teratomas in multiple fetal tissues. The cells were solitary and indistinguishable from surrounding host cells. Transplanted cynomolgus ES cells can be engrafted in allogeneic fetuses. The cells will, however, form a tumor if they "leak" into an improper space such as the thoracic cavity.

Highly efficient gene transfer into primate embryonic stem cells with a simian lentivirus vector.

The ability to stably introduce genetic material into primate embryonic stem (ES) cells could allow their broader application. We previously derived ES cell lines from cynomolgus monkey blastocysts. In this study, we examined lentiviral gene transfer into cynomolgus ES cells. When cynomolgus ES cells were transduced once with a simian immunodeficiency virus (SIV)-based lentivirus vector encoding the green fluorescent protein (GFP) gene, most cells (around 90%) fluoresced, and high levels of GFP expression persisted for 5 months without selection procedures. In addition, high levels of GFP expression were observed during embryoid body formation. On the other hand, transduction of mouse ES cells with the SIV-based vector resulted in lower gene transfer rates, implying that SIV vectors can transduce primate ES cells more efficiently than mouse ES cells. The use of GFP as a reporter gene allows direct and simple detection of successfully transduced ES cells and facilitates monitoring of ES cell proliferation and differentiation both in vitro and potentially in vivo. Furthermore, this highly efficient gene transfer method allows faithful gene delivery to primate ES cells with potential for both research and therapeutic application.