OMU uses discarded sperm and eggs to establish feline embryonic stem cells: Maintained undifferentiated states over time and can differentiate into the three germ layers

A research group led by Professor Shingo Hatoya of the Graduate School of Veterinary Science and Graduate Student Takumi Yoshida of the Graduate School of Life and Environmental Sciences at Osaka Metropolitan University has announced that they succeeded in establishing high-quality feline embryonic stem (ES) cells through production of fertilized eggs by in vitro fertilization of sperm and eggs collected from testes and ovaries, which were discarded after castration and ovariohysterectomy procedures on cats. They were able to establish high-quality feline ES cells capable of remaining undifferentiated over passages of time and differentiating into the three germ layers, by isolating inner cell masses from blastocysts and culturing them in the same medium as one used for human ES and induced pluripotent stem (iPS) cells. The established feline ES cells are expected to be useful for the conservation of endangered wild cat species as well as veterinary regenerative medicine research. The results were published in the international journal Regenerative Therapy on December 2.

No established effective treatments are available for many chronic diseases of cats, and there is a need to develop new treatments. The realization of therapies using iPS and ES cells is also awaited in the field of veterinary medicine. Recently, feline iPS cells have been produced; however, no ES cell lines have been available. Research into these cells is important for evaluating the undifferentiated status and pluripotent potential of iPS cells. Its importance in feline iPS cell research is considered equal to that in human iPS cell research.

In this study, the research group focused on ovaries and testes that were removed and discarded during ovariohysterectomy and castration procedures on cats, which are commonly performed in veterinary clinics. Fertilized eggs (blastocysts) were prepared by fertilizing the collected eggs and sperm on a Petri dish. The inner cell masses, which are part of the cells of blastocysts, were cultured together with mouse embryonic fibroblasts (MEF). Through this the group successfully obtained feline ES cells. The resulting feline ES cells expressed markers of undifferentiated stem cells (OCT3/4, SOX2) and remained undifferentiated after long-term culture.

The research group also succeeded in producing embryoid bodies by suspension culture of feline ES cells. The expression of genes and proteins characteristic of each of the three germ layers (endoderm, mesoderm, and ectoderm) in the embryoid bodies was confirmed, indicating that feline ES cells are pluripotent and capable of differentiating into all of the three germ layers in vitro. Furthermore, feline ES cells transplanted into the testes of immunodeficient mice formed masses.

Pathological evaluation of the masses revealed that they were a special type of tumor (teratoma) containing the three germ layer tissues, indicating that feline ES cells are pluripotent and capable of differentiating into the three germ layers and forming teratomas in vivo. A total of three lines of feline ES cells were established, and all of them maintained a normal chromosome count.

Hatoya said, "Currently, cats are family members, but many of their diseases are untreatable or remain to be elucidated. To solve this problem, we have succeeded in establishing feline ES cells as a result of years of research. Our research group has already generated feline iPS cells, and we would like to compare these two types of cells to facilitate feline regenerative medicine research. We also hope to apply these cell lines to conservation research on endangered wild cat species."

Journal Information
Publication: Regenerative Therapy
Title: Establishment of feline embryonic stem cells from the inner cell mass of blastocysts produced in vitro
DOI: 10.1016/j.reth.2024.11.010