Establishment of an embryonic stem (ES) cell line derived from a non-obese diabetic (NOD) mouse: in vivo differentiation into lymphocytes and potential for germ line transmission

Derivation of embryonic stem cells from wild-derived mouse strains by nuclear transfer using peripheral blood cells

Wild-derived mouse strains have been extensively used in biomedical research because of the high level of inter-strain polymorphisms and phenotypic variations. However, they often show poor reproductive performance and are difficult to maintain by conventional in vitro fertilization and embryo transfer. In this study, we examined the technical feasibility of derivation of nuclear transfer embryonic stem cells (ntESCs) from wild-derived mouse strains for their safe genetic preservation. We used leukocytes collected from peripheral blood as nuclear donors without sacrificing them. We successfully established 24 ntESC lines from two wild-derived strains of CAST/Ei and CASP/1Nga (11 and 13 lines, respectively), both belonging to Mus musculus castaneus, a subspecies of laboratory mouse. Most (23/24) of these lines had normal karyotype, and all lines examined showed teratoma formation ability (4 lines) and pluripotent marker gene expression (8 lines). Two male lines examined (one from each strain) were proven to be competent to produce chimeric mice following injection into host embryos. By natural mating of these chimeric mice, the CAST/Ei male line was confirmed to have germline transmission ability. Our results demonstrate that inter-subspecific ntESCs derived from peripheral leukocytes could provide an alternative strategy for preserving invaluable genetic resources of wild-derived mouse strains.

Induction and maintenance of specific multipotent progenitor stem cells synergistically mediated by Activin A and BMP4 signaling

We recently reported that epiblast stem cells (EpiSCs)-like cells could be derived from preimplantation embryos (named as AFSCs). Here, we established AFSCs from pre-implantation embryos of multiple mouse strains and showed that unlike EpiSCs, the derivation efficiency of AFSCs was affected by the genetic background. We then used AFSCs lines to dissect the roles of Activin A (Act A) and basic fibroblast growth factor and reported that Act A alone was capable of maintaining self-renewal but not developmental potential in vivo. Finally, we established a novel experimental system, in which AFSCs were efficiently converted to multipotent progenitor stem cells using Act A and bone morphogenetic protein 4 (named as ABSCs). Importantly, these ABSCs contributed to neural mesodermal progenitors and lateral plate mesoderm in postimplantation chimeras. Taken together, our study established a robust experimental system for the generation of specific multipotent progenitor stem cells that was self-renewable and capable of contributing to embryonic and extra-embryonic tissues.

Efficient derivation of extended pluripotent stem cells from NOD-scid Il2rg-/- mice

Recently we have established a new culture condition enabling the derivation of extended pluripotent stem (EPS) cells, which, compared to conventional pluripotent stem cells, possess superior developmental potential and germline competence. However, it remains unclear whether this condition permits derivation of EPS cells from mouse strains that are refractory or non-permissive to pluripotent cell establishment. Here, we show that EPS cells can be robustly generated from non-permissive NOD-scid Il2rg^−/− mice through de novo derivation from blastocysts. Furthermore, these cells can also be efficiently generated by chemical reprogramming from embryonic NOD-scid Il2rg^−/− fibroblasts. NOD-scid Il2rg^−/− EPS cells can be expanded for more than 20 passages with genomic stability and can be genetically modified through gene targeting. Notably, these cells contribute to both embryonic and extraembryonic lineages in vivo. More importantly, they can produce chimeras and integrate into the E13.5 genital ridge. Our study demonstrates the feasibility of generating EPS cells from refractory mouse strains, which could potentially be a general strategy for deriving mouse pluripotent cells. The generation of NOD-scid Il2rg^−/− EPS cell lines permits sophisticated genetic modification in NOD-scid Il2rg^−/− mice, which may greatly advance the optimization of humanized mouse models for biomedical applications.

LIF signal in mouse embryonic stem cells

Since the establishment of mouse embryonic stem cells (mESCs) in the 1980s, a number of important notions on the self-renewal of pluripotent stem cells in vitro have been found. In serum containing conventional culture, an exogenous cytokine, leukemia inhibitory factor (LIF), is absolutely essential for the maintenance of pluripotency. In contrast, in serum-free culture with simultaneous inhibition of Map-kinase and Gsk3 (so called 2i-culture), LIF is no longer required. However, recent findings also suggest that LIF may have a role not covered by the 2i for the maintenance of naïve pluripotency. These suggest that LIF functions for the maintenance of naïve pluripotency in a context dependent manner. We summarize how LIF-signal pathway is converged to maintain the naïve state of pluripotency.

The differential activation of intracellular signaling pathways confers the permissiveness of embryonic stem cell derivation from different mouse strains

The requirement of leukemia inhibitory factor (LIF) for the establishment and maintenance of mouse embryonic stem cells (ESCs) depends on the genetic background of the ESC origin. To reveal the molecular basis of the strain-dependent function of LIF, we compared the activation of the intracellular signaling pathways downstream of LIF in ESCs with different genetic backgrounds. We found that the JAK-Stat3 pathway was dominantly activated in ESCs derived from 'permissive' mouse strains (129Sv and C57BL6), whereas the MAP kinase pathway was hyperactivated in ESCs from 'non-permissive' strains (NOD, CBA and FVB). Artificial activation of Stat3 supported stable self-renewal of ESCs from non-permissive strains. These data suggest that the difference in the balance between the two intracellular signaling pathways underlies the differential response to LIF.

Suppression of Th1-mediated autoimmunity by embryonic stem cell-derived dendritic cells

We herein demonstrate the immune-regulatory effect of embryonic stem cell-derived dendritic cells (ES-DCs) using two models of autoimmune disease, namely non-obese diabetic (NOD) mice and experimental autoimmune encephalomyelitis (EAE). Treatment of pre-diabetic NOD mice with ES-DCs exerted almost complete suppression of diabetes development during the observation period for more than 40 weeks. The prevention of diabetes by ES-DCs was accompanied with significant reduction of insulitis and decreased number of Th1 and Th17 cells in the spleen. Development of EAE was also inhibited by the treatment with ES-DCs, and the therapeutic effect was obtained even if ES-DCs were administrated after the onset of clinical symptoms. Treatment of EAE-induced mice with ES-DCs reduced the infiltration of inflammatory cells into the spinal cord and suppressed the T cell response to the myelin antigen. Importantly, the ES-DC treatment did not affect T cell response to an exogenous antigen. As the mechanisms underlying the reduction of the number of infiltrating Th1 cells, we observed the inhibition of differentiation and proliferation of Th1 cells by ES-DCs. Furthermore, the expression of VLA-4α on Th1 cells was significantly inhibited by ES-DCs. Considering the recent advances in human induced pluripotent stem cell-related technologies, these results suggest a clinical application for pluripotent stem cell-derived dendritic cells as a therapy for T cell-mediated autoimmune diseases.

Efficient genetic manipulation of the NOD-Rag1-/-IL2RgammaC-null mouse by combining in vitro fertilization and CRISPR/Cas9 technology

Humanized mouse models have become increasingly important and widely used in modeling human diseases in biomedical research. Immunodeficient mice such as NOD-Rag1-/-IL2RgammaC-null (NRG) or NOD-SCID-IL2RgammaC-null (NSG) mice are critical for efficient engraftment of human cells or tissues. However, their genetic modification remains challenging due to a lack of embryonic stem cells and difficulty in the collection of timed embryos after superovulation. Here, we report the generation of gene knockout NRG mice by combining in vitro fertilization (IVF) and CRISPR/Cas9 technology. Sufficient numbers of fertilized embryos were produced through IVF, and a high rate of Fah gene targeting was achieved with microinjection of Cas9 mRNA, gRNA and single strand oligonucleotide DNA (ssDNA) into the embryos. The technology paves the way to construct NRG or NSG mutant mice to facilitate new humanized mouse models. The technology can also be readily adapted to introduce mutations in other species such as swine and non-human primates.

Improved establishment of embryonic stem (ES) cell lines from the Chinese Kunming mice by hybridization with 129 mice

Chinese Kunming mice (Mus musculus Km), widely used as laboratory animals throughout China, remain very refractory for embryonic stem (ES) cell isolation. The present study was aimed to evaluate the effects of hybridization with 129/Sv mice, and culture media containing fetal bovine serum (FBS) or Knockout serum replacement (KSR) on ES cell isolation from Kunming mice. The results demonstrated that ES cells had been effectively isolated from the hybrid embryos of Kunming and 129/Sv mice using all three media containing 15% FBS, 15% KSR and their mixture of 14% KSR and 1% FBS, individually. These isolated ES cells had maintained in vitro undifferentiated for a long time, exhibiting all features specific for mouse ES cells. In addition, the rates of ES cell isolation in the medium containing 14% KSR and 1% FBS, was 46.67% and significantly higher than those in another two media containing only FBS or KSR (p < 0.05). Contrarily, no ES cell line had been established from Kunming mouse inbred embryos using the same protocols. These results suggested that ES cells with long-term self-renewal ability could be efficiently generated from hybrid embryos of Kunming and 129/Sv mice, and a small volume of FBS was necessary to isolate ES cells in the KSR medium when embryos and early ES cells cultured.

Derivation and characterization of mouse embryonic stem cells from permissive and nonpermissive strains

Mouse embryonic stem cells (mESCs) are key tools for genetic engineering, development of stem cell-based therapies and basic research on pluripotency and early lineage commitment. However, successful derivation of germline-competent embryonic stem cell lines has, until recently, been limited to a small number of inbred mouse strains. Recently, there have been considerable advances in the field of embryonic stem cell biology, particularly in the area of pluripotency maintenance in the epiblast from which the mESCs are derived. Here we describe a protocol for efficient derivation of germline-competent mESCs from any mouse strain, including strains previously deemed nonpermissive. We provide a protocol that is generally applicable to most inbred strains, as well as a variant for nonpermissive strains. By using this protocol, mESCs can be derived in 3 weeks and fully characterized after an additional 12 weeks, at efficiencies as high as 90% and in any strain background.

Isolation and culture of bovine embryonic stem cells

Isolation and culture of primary embryonic stem (ES) cell colonies are the first critical step towards establishment of stable ES cell lines. Here we introduce a novel method designated as "Separate and Seed" that contributes remarkably to efficient derivation of bovine primary ES cell colonies from blastocysts. The bovine ES cell colonies can self-renew to passage 10 with the growth factors bFGF and BIO. The bovine ES cells exhibit morphology typical of ES cells and express pluripotent molecular markers including Oct4, Nanog, SSEA1, SSEA4, and alkaline phosphatase (AP). These pluripotent markers may be used for the characterization of authentic bovine ES cell lines. Although continued efforts are required for improving long-term culture of bovine ES cells, this novel "Separate and Seed" method plus the growth factors bFGF and BIO provides an initial effective step that may eventually lead to the derivation of authentic bovine ES cells.

Comparative genetics: synergizing human and NOD mouse studies for identifying genetic causation of type 1 diabetes

Although once widely anticipated to unlock how human type 1 diabetes (T1D) develops, extensive study of the nonobese diabetic (NOD) mouse has failed to yield effective treatments for patients with the disease. This has led many to question the usefulness of this animal model. While criticism about the differences between NOD and human T1D is legitimate, in many cases disease in both species results from perturbations modulated by the same genes or different genes that function within the same biological pathways. Like in humans, unusual polymorphisms within an MHC class II molecule contributes the most T1D risk in NOD mice. This insight supports the validity of this model and suggests the NOD has been improperly utilized to study how to cure or prevent disease in patients. Indeed, clinical trials are far from administering T1D therapeutics to humans at the same concentration ranges and pathological states that inhibit disease in NOD mice. Until these obstacles are overcome it is premature to label the NOD mouse a poor surrogate to test agents that cure or prevent T1D. An additional criticism of the NOD mouse is the past difficulty in identifying genes underlying T1D using conventional mapping studies. However, most of the few diabetogenic alleles identified to date appear relevant to the human disorder. This suggests that rather than abandoning genetic studies in NOD mice, future efforts should focus on improving the efficiency with which diabetes susceptibility genes are detected. The current review highlights why the NOD mouse remains a relevant and valuable tool to understand the genes and their interactions that promote autoimmune diabetes and therapeutics that inhibit this disease. It also describes a new range of technologies that will likely transform how the NOD mouse is used to uncover the genetic causes of T1D for years to come.

Genetic analysis of type 1 diabetes: embryonic stem cells as new tools to unlock biological mechanisms in type 1 diabetes

The nonobese diabetic (NOD) mouse has provided an important animal model for studying the mechanism and genetics of type 1 diabetes over the past 30 years. Arguably, the bio-breeding (BB) rat model may be an even closer phenotypic mimic of the typical human disease. A large number of distinct genetic traits which influence diabetes development have been defined through an extraordinary effort, most conspicuously in the mouse model. However, in both NOD and BB models the lack of availability of robust means for experimental genetic manipulation has restricted our understanding of the mechanisms underlying this spontaneous autoimmune disease. Recent developments in the derivation of embryonic stem (ES) cells have the potential to transform this picture. We argue here that targeting of NOD strain ES cells can bring much needed certainty to our present understanding of the genetics of type 1 diabetes in the NOD mouse. In addition, ES cells can play important roles in the future, in both the NOD mouse and BB rat models, through the generation of new tools to investigate the mechanisms by which genetic variation acts to promote diabetes.

Optimization of protocols for derivation of mouse embryonic stem cell lines from refractory strains, including the non obese diabetic mouse

The derivation of pluripotent embryonic stem cells (ESCs) from a variety of genetic backgrounds remains a desirable objective in the generation of mice functionally deficient in genes of interest and the modeling of human disease. Nevertheless, disparity in the ease with which different strains of mice yield ESC lines has long been acknowledged. Indeed, the generation of bona fide ESCs from the non obese diabetic (NOD) mouse, a well-characterized model of human type I diabetes, has historically proved especially difficult to achieve. Here, we report the development of protocols for the derivation of novel ESC lines from C57Bl/6 mice based on the combined use of high concentrations of leukemia inhibitory factor and serum-replacement, which is equally applicable to fresh and cryo-preserved embryos. Further, we demonstrate the success of this approach using Balb/K and CBA/Ca mice, widely considered to be refractory strains. CBA/Ca ESCs contributed to the somatic germ layers of chimeras and displayed a very high competence at germline transmission. Importantly, we were able to use the same protocol for the derivation of ESC lines from nonpermissive NOD mice. These ESCs displayed a normal karyotype that was robustly stable during long-term culture, were capable of forming teratomas in vivo and germline competent chimeras after injection into recipient blastocysts. Further, these novel ESC lines efficiently formed embryoid bodies in vitro and could be directed in their differentiation along the dendritic cell lineage, thus illustrating their potential application to the generation of cell types of relevance to the pathogenesis of type I diabetes.

Simple and efficient derivation of mouse embryonic stem cell lines using differentiation inhibitors or proliferation stimulators

The inhibition of endogenous differentiation-inducing signaling or the enhancement of growth capacity and viability of preimplantation embryos, via 2i (PD0325901 and CHIR99021), dramatically improves the establishment of mouse embryonic stem cells (mESCs). Using adrenocorticotropic hormone fragments 1-24 (ACTH 1-24), which enhances survival and/or proliferation of mESCs, also increases the derivation of mESCs from single blastomeres significantly. The CHIR99021 pathway and the proposed ACTH pathway are likely different. Therefore, this study aimed to assess the synergetic effects of 2i and ACTH 1-24 on derivation of mESCs. Results in the present study demonstrate that germline-transmitted mESCs could be efficiently derived from ICR and C57BL/6J at 0.5-4.5 days postcoitum denuded zygotes to blastocysts or isolated blastomeres of 2-8-cell embryos and cultured in 10 μL droplets with human foreskin fibroblast (Hs68) or STO (a mouse embryonic fibroblast line) feeders and in knockout serum replacement (KSR) ESC medium containing 2i or ACTH 1-24. The overall success rates for C57BL/6J and ICR were 56.2% when cultured in 2i+ACTH 1-24, 26.6% in 2i, 6.7% in ACTH 1-24, and 4.8% in KSR ESC medium. These results imply that CHIR99021 and ACTH 1-24 are synergistically enhancing the establishment of mESCs. The proposed protocol also demonstrates a highly efficient and reproducible method, has a simple layout, is easy to apply, and could be used as an alternative method for routinely establishing mESC lines.

Generation of stable pluripotent stem cells from NOD mouse tail-tip fibroblasts

OBJECTIVE

The NOD mouse strain has been widely used to investigate the pathology and genetic susceptibility for type 1 diabetes. Induced pluripotent stem cells (iPSCs) derived from this unique mouse strain would enable new strategies for investigating type 1 diabetes pathogenesis and potential therapeutic targets. The objective of this study was to determine whether somatic fibroblasts from NOD mice could be reprogrammed to become iPSCs, providing an alternative source of stem cells for the production of genetically modified NOD cells and mice.

RESEARCH DESIGN AND METHODS

Adult tail-tip fibroblasts from male NOD mice were reprogrammed by retroviral transduction of the coding sequences of three transcription factors, OCT4, SOX2, and KLF4, in combination with a histone deacetylase inhibitor, valproic acid.

RESULTS

Eighteen NOD iPSC lines were generated, and three of these cell lines were further characterized. All three cell lines exhibited silencing of the three reprogramming transgenes and reactivation of endogenous pluripotent markers (OCT4, SOX2, NANOG, REX1, and SSEA1). These NOD iPSCs readily differentiated in vitro to form embryoid bodies and in vivo by teratoma formation in immunodeficient mice. Moreover, NOD iPSCs were successfully transfected with a reporter transgene and were capable of contributing to the inner cell mass of C57BL/6 blastocysts, leading to the generation of a chimeric mouse.

CONCLUSIONS

Adult tail-tip fibroblasts from NOD mice can be reprogrammed, without constitutive ectopic expression of transcription factors, to produce iPSCs that exhibit classic mouse embryonic stem cell (ESC) features. These NOD iPSCs can be maintained and propagated under normal ESC culture conditions to produce genetically altered cell lines, differentiated cells, and chimeric mice.

Male germline and embryonic stem cell lines from NOD mice: efficient derivation of GS cells from a nonpermissive strain for ES cell derivation

The nonobese diabetic (NOD) mouse is a valuable model for human type 1 diabetes and the development of humanized mice. Although the importance of this mouse strain is widely recognized, its usefulness is constrained by the absence of NOD embryonic stem (ES) lines with adequate germline transmission competence. In the present study, we established two germline transmission-competent types of cell lines from NOD mice; these cell lines, male germline stem (GS) cells and ES cells, were derived from NOD spermatogonia and blastocysts, respectively. NOD-GS cells proliferated in vitro and differentiated into mature sperm after transplantation into testis. NOD-ES cell lines were effectively established from NOD blastocysts using culture medium containing inhibitors for fibroblast growth receptor, MEK, and GSK3. Both the NOD-GS and NOD-ES cell lines transmitted their haplotypes to progeny, revealing a novel strategy for gene modification in a pure NOD genetic background. Our results also suggest that the establishment of GS cells is an effective procedure in nonpermissive mouse strains or other species for ES cell derivation.

Pluripotin combined with leukemia inhibitory factor greatly promotes the derivation of embryonic stem cell lines from refractory strains

Most mouse embryonic stem (ES) cells are derived from a 129 or C57BL/6 background, whereas the derivation efficiency of ES cells is extremely low on certain refractory types of background for which ES cells are highly desired. Here we report an optimized, highly efficient protocol by combining pluripotin, a small molecule, and leukemia inhibitory factor (LIF) for the derivation of mouse ES cells. With this method, we successfully isolated ES cell lines from five strains of mice, with an efficiency of 57% for NOD-scid, 63% for SCID beige, 80% for CD-1, and 100% for two F1 strains from C57BL/6xCD-1. By tracking the Oct4-positive cells in the Oct4-green fluorescent protein embryos in the process of ES cell isolation, we found that pluripotin combined with LIF improved the efficiency of ES cell isolation by selectively maintaining the Oct4-positive cells in the outgrowth. To our knowledge, this is the first report of ES cells being efficiently derived from immunodeficient mice on refractory backgrounds (NOD-scid on a NOD background and SCID beige on a BALB/c background).

Isolation and culture of primary bovine embryonic stem cell colonies by a novel method

Authentic bovine embryonic stem (ES) cell lines have not been established despite progress made for more than two decades. Isolation and culture of primary ES cell colonies are the first critical step towards establishment of stable ES cell lines. Here we report a novel method designated as "Separate and Seed" that contributes remarkably to efficient derivation of bovine primary ES-like cell colonies from blastocysts. These primary cultured bovine ES-like cells exhibit morphology typical of ES cells and express pluripotent molecular markers including Oct4, Nanog and alkaline phosphatase. Interestingly, bovine primary ES-like cell colonies distinctively express both stage-specific embryonic antigens 1 and 4 (SSEA1 and SSEA4), unlike mouse and human ES cells. These pluripotent markers may be used for characterization of authentic bovine ES cell lines in later studies. In contrast, whole embryos or inner cell mass (ICM) used for primary culture by conventional methods fails to produce primary bovine ES cell colonies that express all pluripotent stem cell markers shown above. Furthermore, bFGF improves growth and maintained undifferentiated state of bovine ES-like cells for several passages, whereas LIF and ERK inhibitor PD98059 known to promote pluripotency of mouse ES cells are unable to sustain bovine ES-like cells. Although continued efforts are required for improving long-term culture of bovine ES cells, this novel "Separate and Seed" method provides an initial effective step that may eventually lead to derivation of authentic bovine ES cell lines.

Amino acid polymorphisms altering the glycosylation of IL-2 do not protect from type 1 diabetes in the NOD mouse

Idd3 is one of many gene regions that affect the development of type 1 diabetes (T1D) in the nonobese diabetic (NOD) mouse. Idd3 has been localized to a 650-kb region on chromosome 3 containing the IL-2 gene. Exon 1 of the IL-2 gene is polymorphic between the susceptible NOD and the protective C57BL/6 (B6) alleles, causing multiple amino acid changes that have been proposed to be responsible for the differing glycosylation status. To address whether this coding polymorphism recapitulates the disease suppression mediated by the B6 Idd3 allele, we generated knockin mice in which exon 1 of the B6 IL-2 allele replaces the homologous region in the NOD allele. We generated these mice by targeting the NOD allele of NOD/129 F(1) ES cells. IL-2 protein from the knockin mice showed the glycosylation pattern of the B6 IL-2 isoform, confirming that the amino acid differences encoded within exon 1 affect the glycosylation of the IL-2 protein. However, unlike NOD.B6 Idd3 congenic mice, the knockin mice were not protected from T1D. Furthermore, the difference in amino acid sequence in the IL-2 protein did not affect the level of expression of IL-2. This approach provides a general method for the determination of a functional role of a given genomic sequence in a disease process. Further, our result demonstrates that the variants in exon 1 of the IL-2 gene are not responsible for T1D suppression in NOD.B6 Idd3 mice, thereby supporting the hypothesis that variants in the regulatory region affecting expression levels are causative.

NOD x 129.H2(g7) backcross delineates 129S1/SvImJ-derived genomic regions modulating type 1 diabetes development in mice

OBJECTIVE

Introduction of genes targeted in 129/Sv embryonic stem (ES) cells into NOD mice brings about linked genes that may modulate type 1 diabetes. Our objective was to identify 129S1/SvJ non-MHC regions contributing type 1 diabetes resistance or susceptibility in backcross to NOD/LtJ.

RESEARCH DESIGN AND METHODS

After congenic transfer of the NOD H2(g7) haplotype onto 129S1/Sv, 310 females were produced by NOD x (NOD x 129.H2(g7))F1 backcross (N2). A genome scan for quantitative trait locus (QTL) affecting clinical diabetes, age of diabetes onset, and insulitis severity was performed using subphenotype characteristics to improve power and resolution for detection of diabetes susceptibility loci.

RESULTS

Thirty-six of 310 (11.6%) N2 females developed type 1 diabetes between 14 and 40 weeks. Significant evidence of linkage for only a single previously reported Idd complex locus (Idd10/17/18, chromosome [Chr] 3) was indicated for clinical diabetes. The quantitative traits of insulitis either alone or combined with age at type 1 diabetes onset were significantly linked to known Idd regions on Chr 1 (Idd5 region), Chr 4 (Idd9 region), Chr 8 (Idd22), Chr 11 (Idd4.3), and proximal Chr 17 (Idd16 region). Significant 129S1/Sv resistance contributions were identified on Chr 1, 15 (two loci), and 19, with suggestive evidence for additional novel 129/Sv resistance QTL on Chr 5 and 17 and susceptibility on Chr 2.

CONCLUSIONS

The 129S1/SvJ genome harbors collections of both known and potentially novel non-MHC Idd loci. Investigators targeting 129/Sv genes mapping within chromosomal regions reported herein or elsewhere in the genome need to exclude potential contributions from linked Idd loci by generating a NOD.129 control strain expressing the nontargeted allele.

Validated germline-competent embryonic stem cell lines from nonobese diabetic mice

Nonobese diabetic (NOD) mice provide an excellent model of type 1 diabetes. The genetic contribution to this disease is complex, with more than 20 loci implicated in diabetes onset. One of the challenges for researchers using the NOD mouse model (and, indeed, other models of spontaneous autoimmune disease) has been the high density of sequence variation within candidate chromosomal segments. Furthermore, the scope for analyzing many putative disease loci via gene targeting has been hampered by the lack of NOD embryonic stem (ES) cells. We describe here the derivation of NOD ES cell lines capable of generating chimeric mice after stable genetic modification. These NOD ES cell lines also show efficient germline transmission, with offspring developing diabetes. The availability of these cells will not only enable the dissection of closely linked loci and the role they have in the onset of type 1 diabetes but also facilitate the generation of new transgenics.

ES cell line establishment

A method is described to establish mouse embryonic stem cell (ESC) lines from hybrid and inbred strains of mice. Attention is paid not only to the methodology for isolation and culture but also to the validation of freshly derived lines, in order to be maintained for prolonged time without significant differentiation or karyotype instability, and to provide reproducible germline transmission in chimaeric mice.

Serum replacement with a growth factor-free synthetic substance in culture medium contributes to effective establishment of mouse embryonic stem cells of various origins

OBJECTIVE

To evaluate whether serum replacement with growth factor-free synthetic substances contributed to the effective establishment of embryonic stem (ES) cells.

DESIGN

Randomized, prospective model study.

SETTING

Gamete and stem cell biotechnology laboratory at Seoul National University in Korea.

ANIMAL(S)

F1 (C57BL6 x DBA2) mice.

INTERVENTION(S)

Blastocysts of different origins were cultured in serum-replaced media.

MAIN OUTCOME MEASURE(S)

Embryonic stem cell establishment.

RESULT(S)

Eight batches of ES cells were established from colony-forming inner cell mass cells after the replacement of fetal bovine serum (FBS) with synthetic knockout serum replacement (KSR) in mkDMEM. The established cells were positive for ES cell markers and formed both embryoid bodies in vitro and teratomas in vivo, but the established cell batches and control (transformed) ES cells responded differently to the culture media. Higher levels of cell viability were detected after the replacement with the 75:25 FBS-KSR mixture than with any other mixtures, and a gradual decrease in viability was detected as the KSR volume ratio was increased. The 75:25 FBS-KSR mixture-containing medium supported ES cell establishment of outbred ICR, F1, and F2 of C57BL6/DBA2; F1 parthenogenetic and ES cell-complemented tetraploid blastocysts; and single ES-cell cultures.

CONCLUSION(S)

A serum-replaced medium could be used for effective ES-cell establishment of various origins.

"Agouti NOD": identification of a CBA-derived Idd locus on Chromosome 7 and its use for chimera production with NOD embryonic stem cells

Penetrance of the complex of genes predisposing the nonobese diabetic (NOD) mouse to autoimmune diabetes is affected by the maternal environment. NOD.CBALs-Tyr(+)/Lt is an agouti-pigmented Chromosome 7 congenic stock of NOD/Lt mice produced as a resource for embryo transfer experiments to provide the necessary maternal factors and allow the easy identification of NOD (albino) embryo donor phenotype. CBcNO6/Lt, a recombinant congenic agouti stock already containing approximately 50% NOD genome, was used as the donor source of a wild-type CBA tyrosinase allele. When the incidence of diabetes was assessed after nine generations of backcrossing and one generation of sib-sib mating, significant reduction in diabetes development was observed. No difference in diabetes development was observed in Tyr/Tyr(c) heterozygotes, showing that protection was recessive. Analysis of diabetes progression in another NOD stock congenic for C57BL/6 alleles on Chromosome 7 linked to the glucose phosphate isomerase (Gpi1(b)) locus provided no protection, indicating that the diabetes resistance (Idd) gene was distal to 34 cM (D7Mit346). Approximately 5 cM of the distal congenic region overlaps a region from C57L previously associated with protection when homozygous. The delayed onset and reduced frequency of diabetes in the NOD.CBALs-Tyr(+)/Lt stock is an advantage when females of this stock are used as surrogate mothers in studies involving hysterectomy or embryo transfers. Indeed, a newly developed NOD embryonic stem (ES) cell line injected into NOD.CBALs- Tyr(+)/Lt blastocysts produced approximately 50% live-born mice, of which approximately 11% were chimeric. Presumably because of high genomic instability, no germline transmission was observed.

Congenic mice: cutting tools for complex immune disorders

Autoimmune diseases are, in general, under complex genetic control and subject to strong interactions between genetics and the environment. Greater knowledge of the underlying genetics will provide immunologists with a framework for study of the immune dysregulation that occurs in such diseases. Ascertaining the number of genes that are involved and their characterization have, however, proven to be difficult. Improved methods of genetic analysis and the availability of a draft sequence of the complete mouse genome have markedly improved the outlook for such research, and they have emphasized the advantages of mice as a model system. In this review, we provide an overview of the genetic analysis of autoimmune diseases and of the crucial role of congenic and consomic mouse strains in such research.

The derivation of highly germline-competent embryonic stem cells containing NOD-derived genome

It would be extremely advantageous to the analysis of disease mechanisms in the spontaneous mouse model of type 1 diabetes, the nonobese diabetic (NOD) strain, if genes in this strain could be modified in vivo using embryonic stem (ES) cells and homologous recombination. However, a NOD ES cell line with adequate germline transmission has not yet been reported. We report the development of highly germline-competent ES cell lines from the F1 hybrid of NOD and 129 for use in NOD gene targeting. Consequently, we developed ES cell lines derived from (NOD x 129)F1 x 129 backcross 1 mice, which were intercrossed to select for homozygosity of particular regions of NOD genome known to contain disease loci.

Beta cell destruction in the development of autoimmune diabetes in the non-obese diabetic (NOD) mouse

In the non-obese diabetic (NOD) mouse model of Type 1 (insulin-dependent) diabetes, evidence suggests that pancreatic beta cells are destroyed in part by apoptotic mechanisms. The precise mechanisms of beta cell destruction leading to diabetes remain unclear. The NOD mouse has been studied to gain insight into the cellular and molecular mediators of beta cell death, which are discussed in this review. Perforin, secreted by CD8(+) T cells, remains one of the only molecules confirmed to be implicated in beta cell death in the NOD mouse. There are many other molecules, including Fas ligand and cytokines such as interferon-gamma, interleukin-1 and tumor necrosis factor-alpha, which may lead to beta cell destruction either directly or indirectly via regulation of toxic molecules such as nitric oxide. As beta cell death can occur in the absence of perforin, these other factors, in addition to other as yet unidentified factors, may be important in the development of diabetes. Effective protection of NOD mice from beta cell destruction may therefore require inhibition of multiple effector mechanisms.