Production of feline leukemia inhibitory factor with biological activity in Escherichia coli

Effects of the preservation medium and storage duration of domestic cat ovaries on the maturational and developmental competence of oocytes in vitro

We examined the effectiveness of saline, Euro-Collins solution (EC), and ET-Kyoto solution (ET-K) as preservation media for the cold storage of feline ovaries. Ovaries were maintained in these media at 4°C for 24, 48, or 72 h until oocyte retrieval. The ET-K group exhibited a higher oocyte maturation rate than the saline group after 72 h of storage. Moreover, ET-K could sustain the competence of the feline oocytes to cleave after 48 h, and the morula formation rate of the ET-K group was higher than that of the other groups after 24 and 48 h. Furthermore, the ET-K group exhibited a higher blastocyst formation rate than the other groups after storage for 24 h, and only ET-K retained the developmental competence in blastocysts after 48 h of storage. In addition, regarding the cell numbers of the blastocysts, there was no significant difference among the tested groups. In conclusion, our results indicate that ET-K is a suitable preservation medium for feline ovaries.

Development of feline embryos produced using freeze-dried sperm

Freeze drying has been developed as a new sperm preservation method that eliminates the necessity of using liquid nitrogen. An advantage of freeze-dried sperm is that it can be stored at 4 °C and transported at room temperature. To develop assisted reproductive techniques (ARTs) for domestic cats, we evaluated the effect of the freeze-dry procedure on cat sperm DNA by analyzing DNA integrity (experiment 1) and by generating cat embryos using freeze-dried sperm that had been preserved for several months (experiment 2). In experiment 1, the rate of DNA damage to freeze-dried sperm was not significantly different than that of sperm cryopreserved with liquid nitrogen (P > 0.05). In experiment 2, the proportions of cleaved embryos, morulae, and blastocysts and the cell number of blastocysts did not differ between experimental groups in which fresh sperm and freeze-dried sperm were used (P > 0.05). In addition, we generated feline blastocysts using freeze-dried sperm stored for 1-5 months. These results support an expansion of the repertoire of ARTs that are potentially applicable to both domestic and endangered species of cats.

Leukemia inhibitory factor: Recent advances and implications in biotechnology

Leukemia inhibitory factor (LIF) is a pleiotropic cytokine with several functions in health and disease ranging from inflammation to cancer. LIF is also a potential target and/or therapeutic agent for diseases such as multiple sclerosis, stroke and even psychological disorders, where the function of LIF as a neurotrophic factor has only recently been explored. In recent years, a limited number of LIF clinical trials have been completed, which partially explains the shortage of effective applications as a therapeutic agent. With the increasing interest from biotechnology companies producing recombinant LIF, this status quo will certainly change, and the potential impact of LIF in terms of disease diagnosis, treatment and management will be realized.

Inducing Pluripotency in the Domestic Cat (Felis catus)

Domestic cats suffer from a range of inherited genetic diseases, many of which display similarities with equivalent human conditions. Developing cellular models for these inherited diseases would enable drug discovery, benefiting feline health and welfare as well as enhancing the potential of cats as relevant animal models for translation to human medicine. Advances in our understanding of these diseases at the cellular level have come from the use of induced pluripotent stem cells (iPSCs). iPSCs can differentiate into virtually any cell type and can be derived from adult somatic cells, therefore overcoming the ethical implications of destroying embryos to obtain embryonic stem cells. No studies, however, report the generation of iPSCs from domestic cats [feline iPSCs (fiPSCs)]. Feline adipose-derived fibroblasts were infected with amphotropic retrovirus containing the coding sequences for human Oct4, Sox2, Klf4, cMyc, and Nanog. Isolated iPSC clones were expanded on inactivated mouse embryonic fibroblasts in the presence of feline leukemia inhibitory factor (fLIF). Retroviral delivery of human pluripotent genes gave rise to putative fiPSC colonies within 5-7 days. These iPS-like cells required fetal bovine serum and fLIF for maintenance. Colonies were domed with refractile edges, similar to mouse iPSCs. Immunocytochemistry demonstrated positive staining for stem cell markers: alkaline phosphatase, Oct4, Sox2, Nanog, and SSEA1. Cells were negative for SSEA4. Expression of endogenous feline Nanog was confirmed by quantitative polymerase chain reaction. The cells were able to differentiate in vitro into cells representative of the three germ layers. These results confirm the first generation of induced pluripotent stem cells from domestic cats. These cells will provide valuable models to study genetic diseases and explore novel therapeutic strategies.

Development of feline embryos produced by Piezo-actuated intracytoplasmic sperm injection of elongated spermatids

Piezo-actuated intracytoplasmic sperm injection (Piezo-ICSI) is used as an efficient in vitro fertilization method with various animals. With this method, elongated spermatids are collected from testicular tissues and are easier to obtain from animals that unexpectedly die than ejaculate sperm. Additionally, elongated spermatid injection often results in the development of embryos and offspring. To develop assisted reproductive techniques (ARTs) for domestic cats, we examined the effects of oocyte activation on cleavage and embryo development after Piezo-ICSI with motile sperm (experiment 1) and after Piezo-ICSI with either testicular sperm or elongated spermatids (experiment 2). In experiment 1, the proportions of cleaved embryos, morulas, and blastocysts following Piezo-ICSI with ethanol activation were significantly higher (P < 0.05) than in the non-activated groups. However, the proportion of blastocysts and the blastocyst quality did not differ significantly (P > 0.05) between the ethanol-activated and non-activated groups. In experiment 2, the cleavage frequencies of oocytes after Piezo-ICSI of testicular sperm or elongated spermatids and ethanol activation were higher (P < 0.05) than that of oocytes in the non-activated group, but the occurrence of blastocyst formation and quality of blastocysts did not differ between the activated and non-activated groups. In summary, cat embryos can be produced by Piezo-actuated microinjection of elongated spermatids. Ethanol activation increased the frequency of cleavage, but it affected neither the occurrence of blastocyst development nor the quality of blastocysts. These results represent an expansion in the repertoire of ARTs that are potentially applicable to both domestic and endangered species of cats.