Sci­en­tists from Berlin suc­cess­fully pro­duced embryos from African lions via assisted repro­duc­tion. What is gen­uinely new is the fact that they used imma­ture eggs that were retrieved from African lionesses. After arti­fi­cial mat­u­ra­tion these eggs were injected with lions’ sperm, pre­vi­ously stored in a cry­obank. To sur­prise of the sci­en­tists from the Leib­niz Insti­tute for Zoo and Wildlife Research (IZW) the devel­op­ment of the lion embryos was retarded in com­par­i­son to sim­i­lar embryos from domes­tic cats.

The report on the suc­cess of in vitro mat­u­ra­tion and fer­tilisation by sperm injec­tion in African lions (Pan­thera leo) by the repro­duc­tion biol­o­gists of the IZW has been pub­lished online on 5 Decem­ber 2014 in the sci­en­tific mag­a­zine “Theriogenology”.

Assisted repro­duc­tive tech­nolo­gies (ARTs) are becom­ing increas­ingly impor­tant for the breed­ing of endan­gered species. The estab­lished genome resource banks allow the inte­gra­tion of cry­op­re­served genes in exist­ing pop­u­la­tions regard­less of time and space.

Cur­rently indi­vidual ani­mals have to be trans­ported for blood refresh­ment. Ship­ping embryos or just sperm cells would also reduce a pos­si­ble risk of dis­ease trans­mis­sion between Zoos. Fur­ther­more the meth­ods of assisted repro­duc­tion are des­ig­nated to link con­ser­va­tion efforts in the orig­i­nal habi­tat (in-​situ) with cap­tive breed­ing pro­grammes (ex-​situ).

In any cases, the suc­cess­ful use of genome resource banks requires the adap­ta­tion of assisted repro­duc­tive tech­niques to the species spe­cific require­ments. This includes the retrieval of gametes, cul­ture, and cry­op­reser­va­tion as well as arti­fi­cial insem­i­na­tion and embryo trans­fer. “These repro­duc­tive tech­niques are suc­cess­fully applied in med­ical sci­ence and live­stock farm­ing. How­ever, a com­pre­hen­sive basic research is needed, owed by con­sid­er­able dif­fer­ences in anatomy and phys­i­ol­ogy in many endan­gered mam­mals”, explains Kata­rina Jewgenow, head of repro­duc­tion biol­ogy depart­ment of IZW.

Feline car­ni­vores ben­e­fit from the devel­op­ment of repro­duc­tive tech­niques in domes­tic cats. Until now, diverse ARTs have been devel­oped for domes­tic cats. Now the chal­lenge is to make this knowl­edge avail­able for endan­gered felids. “The in-​vitro pro­duced embryos of the African lions proved, that the meth­ods devel­oped for domes­tic cats can also be applied to lions, even though the vari­a­tions devel­op­men­tal speed of the embryos indi­cate some fas­ci­nat­ing dif­fer­ences between these species”, says Lorena Fernandez-​Gonzalez.

Over­all 68 imma­ture oocytes, retrieved after eight-​hour trans­porta­tion, were cul­ti­vated in-​vitro for one and a half days in a spe­cial medium. Over one third of the eggs matured and was fer­til­ized via intra­cy­to­plas­mic sperm injec­tion (ICSI). For this, a sin­gle lion sperm is injected directly into an egg with a micro-​needle. The frozen/​thawed sperm used in this study was from a lion of an Euro­pean zoo, which died in 2012. Even though the sperm cells exhib­ited a lim­ited via­bil­ity after thaw­ing, the fer­til­iza­tion of a few oocytes was suc­cess­ful. This was ver­i­fied by embryo cleav­age, although the advanced blas­to­cyst stage was achieved as late as after nine days cul­ture. In domes­tic cats blas­to­cysts can be observed after seven days already. The rea­sons for the slower devel­op­men­tal speed remain a mys­tery. It could be caused by the retrieval of the gametes post­mortem, the pro­longed trans­porta­tion of the ovaries or even sim­ply be a species-​specific feature.

(Source: IZW press release, 06.02.2015)