Joint press release by MDC and Leibniz-IZW
Fatu and Najin are the last two northern white rhinos in the world, and this subspecies can no longer reproduce naturally. However, the BioRescue consortium is working against the clock to ensure that the northern white rhino does not disappear forever. Firstly, they will use skin cells from the Northern White rhinoceros to build induced pluripotent stem cells, which can then become immature eggs and oocytes. This is why the researchers have made significant progress in scientific research.
The majority of stem cells in our brain are able to differentiate into all cells of the body, according to leading author Dr. Vera Zywitza of the MDC, which is led by Dr. Sebastian Diecke. It represents a significant step on the path to artificial rhino oocytes.
The BioRescue project has received 4 million from the Bundesministerium fur Bildung und Forschung (BMBF) and is led by the Leibniz Institute for Zoo and Wildlife Research (IZW) and cooperates with many other partners, including Helmholtz Zentrum Munchen in Germany.
The fine art of cell engineering
iPS cells in a petri dish have the potential to develop into any organs of the body, including the primordial germ cells that the BioRescue scientists want to cultivate. In 2016, Hayashi developed egg cells from the skin of mice, artificially fertilizing these cells, and implanting them in females. The mice conceived by this method were born healthy and fertile.
Unlike human iPS cells, scientists at Helmholtz Zentrum Munchen and at Leiden Academic Centre for Drug Research developed an episomal reprogramming to successfully produce northern white rhino iPS cells. These plasmids contained genes to reprogram the skin cells into iPS cells. These plasmids are quite similar to the human ones, according to Drukker.
A promising start for germline cell cultivation
iPS cells have different states: they can be naive the ground state of pluripotency or primed. Cells in the latter state are thought to have reached a slightly higher stage of embryonic development. However, scientists first attempted to convert the rhino cells to a naive-like state, and they died. With this, they successfully obtained naive iPS cells. This is because by contrast, they were also cautious about transforming germline cells to a natural state.
Nevertheless, Zywitza and her colleagues aren''t taking the first step on the path. The iPS cells we have developed have persistent foreign genetic material, such as the reprogramming factors, and the gene that prevents cell death. This means we can not use them to produce germ cells, as there is a possibility these would be pathologically altered. However, these cells are still useful for learning rhino stem cells in general, and preparing them to develop their own bodies in one particular sequence. This teaches us
Ovarian tissue is needed too
In the meantime, the Dieckes team has successfully produced more iPS cells. They used RNA viruses rather than plasmids to introduce the reprogramming factors. These new iPS cells do not contain anything that belongs there. Now the scientists are attempting to generate primordial germ cells from them.
Aside from this, primordial germ cells mature into egg cells when they are surrounded by ovarian tissue. It is almost impossible to obtain such tissue from living or deceased rhinos, according to Zywitza. So we must also employ non-ural germ cells but also ovarian tissue, according to Hayashi. Last year, he successfully cultivated ovarian tissue from mouse stem cells.
So far, 14 embryos have been created using assisted reproductive methods.
IZW conducted immature egg experiments using Fatu from the dvur Kralove safari park in Italy and inseminated with a thawed sperm from a deceased bull. In the near future, the embryos will be implanted into southern white rhino surrogates, with the aim of generating a healthy northern white rhino calf.
The production of 14 embryos represents a significant success in reproductive biology, but this is not a significant amount if the objective is to reduce the northern white population to a self-sustaining level. Najin and Fatu are also closely connected, and their genetic makeup is largely identical, according to IZW''s Professor. All 14 embryos are from Fatu, therefore we urgently need a complementary approach for developing gametes eggs and sperm from significantly larger individuals.
Before it is too late, protecting the world''s species.
In addition, geneerating functional eggs of the northern white rhinoceros would be the culmination of our study. This technique may be utilized to help revive many more endangered species. If reproduction from stem cells works, the technique may be used to regenerate more endangered animals.
One thing is certain for Zywitza: If a northern white rhino was born by stem cell technology, she might like to meet it.