ABSTRACT
For the preparation of embryo transfer recipients, surgically vasectomized mice are commonly used, generated by procedures associated with pain and discomfort. Sterile transgenic strains provide a nonsurgical replacement, but their maintenance requires breeding and genotyping procedures. We have previously reported the use of naturally sterile STUSB6F1 hybrids for the production of embryo transfer recipients and found the behavior of these recipients to be indistinguishable from those generated by vasectomized males. The method provides two substantial 3R impacts: refinement (when compared with surgical vasectomy) and reduction in breeding procedures (compared with sterile transgenic lines). Despite initial promise, the 3Rs impact of this innovation was limited by difficulties in breeding the parental STUS/Fore strain, which precluded the wider distribution of the sterile hybrid. The value of a 3R initiative is only as good as the uptake in the community. Here we, thus, select a different naturally sterile hybrid, generated from strains that are widely available: the B6SPRTF1 hybrid between C57BL/6J and Mus spretus. We first confirmed its sterility by sperm counting and testes weight and then trialed the recovery of cryopreserved embryos and germplasm within three UK facilities. Distribution of sperm for the generation of these hybrids by in vitro fertilization was found to be the most robust distribution method and avoided the need to maintain a live M. spretus colony. We then tested the suitability of B6SPRTF1 sterile hybrids for the generation of embryo transfer recipients at these same three UK facilities and found the hybrids to be suitable when compared with surgical vasectomized mice and a sterile transgenic strain. In conclusion, the potential 3Rs impact of this method was confirmed by the ease of distribution and the utility of sterile B6SPRTF1 hybrids at independent production facilities.
Subject(s)
Embryo Transfer , Mice, Inbred C57BL , Animals , Male , Mice , Embryo Transfer/veterinary , Embryo Transfer/methods , Female , Hybridization, Genetic , Pseudopregnancy/genetics , Pseudopregnancy/veterinary , Cryopreservation/veterinary , Fertilization in Vitro/veterinary , Fertilization in Vitro/methods , Vasectomy/veterinary , Vasectomy/methodsABSTRACT
It has been hypothesized that interleukin-1alpha (IL-1α) is released from damaged cardiomyocytes following myocardial infarction (MI) and activates cardiac fibroblasts via its receptor (IL-1R1) to drive the early stages of cardiac remodeling. This study aimed to definitively test this hypothesis using cell type-specific IL-1α and IL-1R1 knockout (KO) mouse models. A floxed Il1α mouse was created and used to generate a cardiomyocyte-specific IL-1α KO mouse line (MIL1AKO). A tamoxifen-inducible fibroblast-specific IL-1R1 hemizygous KO mouse line (FIL1R1KO) was also generated. Mice underwent experimental MI (permanent left anterior descending coronary artery ligation) and cardiac function was determined 4 weeks later by conductance pressure-volume catheter analysis. Molecular markers of remodeling were evaluated at various time points by real-time RT-PCR and histology. MIL1AKO mice showed no difference in cardiac function or molecular markers of remodeling post-MI compared with littermate controls. In contrast, FIL1R1KO mice showed improved cardiac function and reduced remodeling markers post-MI compared with littermate controls. In conclusion, these data highlight a key role for the IL-1R1/cardiac fibroblast signaling axis in regulating post-MI remodeling and provide support for the continued development of anti-IL-1 therapies for improving cardiac function after MI. Cardiomyocyte-derived IL-1α was not an important contributor to post-MI remodeling in this model.
Subject(s)
Fibroblasts/metabolism , Myocardial Infarction/metabolism , Receptors, Interleukin-1 Type I/metabolism , Ventricular Remodeling/physiology , Animals , Cytokines/metabolism , Disease Models, Animal , Fibrosis/metabolism , Heart Failure , Interleukin-1alpha/genetics , Interleukin-1alpha/metabolism , Male , Mice , Mice, Knockout , Myocardial Infarction/pathology , Myocardium/metabolism , Myocardium/pathology , Myocytes, Cardiac/metabolism , Receptors, Interleukin-1 Type I/genetics , Signal TransductionABSTRACT
The in vivo cell reprogramming of terminally differentiated somatic cells to a pluripotent state by the ectopic expression of defined transcription factors has been previously shown in the BALB/c mouse liver upon plasmid DNA injection with no teratoma formation in the host tissue. Here, we hypothesized that the reprogrammed cells could be extracted from the tissue and cultured in vitro. We called these cells in vivo induced pluripotent stem (i(2)PS) cells because they showed pluripotent characteristics equivalent to a standard mouse ES cell line (E14TG2A). The pluripotent character of i(2)PS cells was determined by a battery of morphological, molecular and functional assays, including their contribution to adult tissues of chimeric mice upon blastocyst injection. These observations further confirm that terminally differentiated somatic cells in wild type, adult animals can be reprogrammed in vivo using virus-free methodologies. The reprogrammed cells can generate in vitro stem cell colonies that exhibit pluripotency similar to ES cells with numerous implications for the application of in vivo reprogramming for tissue regenerative purposes.
