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.

Differentiation of enteric neural crest cells transplanted from SOX10-Venus mouse embryonic stem cells into the gut of the endothelin receptor B null mouse model

PURPOSE

Failure of enteric neural crest-derived cells (ENCCs) to correctly colonize the embryonic gut results in Hirschsprung's disease (HD). Embryonic stem cells (ESCs) have the potential to differentiate into all tissue-specific cells and lineages, including ENCCs. We investigated the cellular differentiation of ESCs from Sox10-Venus ⁺ mice into both control and endothelin receptor-B knockout (Ednrb KO) mouse gut to assess each region.

METHODS

We established ESCs from Sox10-Venus ⁺ mice. These cells were cultured for 2 days, then selected and co-cultured with either a dissociated control or Sox10-Venus ^- Ednrb KO mouse gut (both small intestine and colon) on embryonic day (E) 13.5. Four days later, cells were immunolabeled for Tuj1 and visualized using confocal microscopy.

RESULTS

Confocal microscopy revealed that transplanted Sox10-Venu ⁺ cells from ESCs migrated extensively within the host gut. Moreover, Tuj1-positive neurites were detected in the transplanted ESCs. Tuj1 expression was significantly decreased in aganglionic HD colon compared to controls (p < 0.05) and the HD small intestine (p < 0.05).

CONCLUSIONS

This study demonstrated that an appropriate host environment is crucial for normal and complete colonization of the gut. Further investigations are required to confirm whether modifying this environment can improve the results of this model.

Mechanisms of pluripotency maintenance in mouse embryonic stem cells

Mouse embryonic stem cells (mESCs), characterized by their pluripotency and capacity for self-renewal, are driven by a complex gene expression program composed of several regulatory mechanisms. These mechanisms collaborate to maintain the delicate balance of pluripotency gene expression and their disruption leads to loss of pluripotency. In this review, we provide an extensive overview of the key pillars of mESC pluripotency by elaborating on the various essential transcription factor networks and signaling pathways that directly or indirectly support this state. Furthermore, we consider the latest developments in the role of epigenetic regulation, such as noncoding RNA signaling or histone modifications.

Regulatory principles of pluripotency: from the ground state up

Pluripotency is the remarkable capacity of a single cell to engender all the specialized cell types of an adult organism. This property can be captured indefinitely through derivation of self-renewing embryonic stem cells (ESCs), which represent an invaluable platform to investigate cell fate decisions and disease. Recent advances have revealed that manipulation of distinct signaling cues can render ESCs in a uniform "ground state" of pluripotency, which more closely recapitulates the pluripotent naive epiblast. Here we discuss the extrinsic and intrinsic regulatory principles that underpin the nature of pluripotency and consider the emerging spectrum of pluripotent states.

Generation of embryonic stem cells and mice for duchenne research

Duchenne muscular dystrophy (DMD) is a muscle-wasting disease in which muscle is continuously damaged, resulting in loss of muscle tissue and function. Antisense-mediated exon skipping is a promising therapeutic approach for DMD. This method uses sequence specific antisense oligonucleotides (AONs) to reframe disrupted dystrophin transcripts. As AONs function in a sequence specific manner, human specific AONs cannot be tested in the mdx mouse, which carries a mutation in the murine Dmd gene. We have previously generated a mouse model carrying the complete human DMD gene (hDMD mouse) integrated in the mouse genome to overcome this problem. However, as this is not a disease model, it cannot be used to study the effect of AON treatment on protein level and muscle function. Therefore, our long term goal is to generate deletions in the human DMD gene in a mouse carrying the hDMD gene in an mdx background. Towards this aim, we generated a male ES cell line carrying the hDMD gene while having the mdx point mutation. Inheritance of the hDMD gene by the ES cell was confirmed both on DNA and mRNA level. Quality control of the ES cells revealed that the pluripotency marker genes Oct-4 and Nanog are well expressed and that 85% of cells have 40 chromosomes. Germ line competence of this cell line has been confirmed, and 2 mice strains were derived from this cell line and crossed back on a C57BL6 background: hDMD/mdx and mdx(BL6).

A retrospective analysis of germline competence in rat embryonic stem cell lines

The factors responsible for conferring germline competence in embryonic stem (ES) cell lines remain unidentified. In the present study, rat ES cell lines (n = 17) were established with 3i medium (SU5402, PD0325901, CHIR99021), 2i medium (PD0325901, CHIR99021) or 2iF medium (PD0325901, CHIR99021, forskolin), and their potential for germline transmission to the G1 generation was examined. Rat strains were divided into an albino group (F344, Wistar or CAG/Venus transgenic rats with the Wistar background) or a colored coat group (Brown-Norway, Dark-Agouti, or BLK rats selected from >F3 generations of Wistar × Dark-Agouti rats based on their black coat color). Successful germline transmission was observed in 57 % (4/7), 40 % (2/5) and 100 % (5/5) of the ES cells established with 3i, 2i and 2iF media, respectively. ES cell lines from the homozygous CAG/Venus transgenic rats were established in all three media, but only the lines established with the 2iF medium were germline-competent. Neither coat-color (albino: 64 %, 7/11; colored: 67 %, 4/6) nor gender of the ES cell lines (XX: 67 %, 2/3; XY: 64 %, 9/14) were likely to affect germline transmission.