Last September, in Buffalo (USA), at the CARD-RPCI Mouse Sperm and Embryo Cryopreservation course organized by Naomi Nakagata, Aimee Stablewski and Jan Parker-Thornburg, Naomi Nakagata himself presented the preliminary results of an amazing achievement in Reproductive Biology they had accomplished at the University of Kumamoto (Japan), namely: the obtention of more than 100 oocytes per C57BL/6 female after devising a new protocol for superovulation, a method they introduced as ULTRA-superovulation. Now, these totally unexpected results see the light in the form of a scientific manuscript, published yesterday in the PLOS ONE journal:
Toru Takeo & Naomi Nakagata (2015) Superovulation Using the Combined Administration of Inhibin Antiserum and Equine Chorionic Gonadotropin Increases the Number of Ovulated Oocytes in C57BL/6 Female Mice. PLOS ONE, Published: May 29, 2015DOI: 10.1371/journal.pone.0128330
In brief, in this publication, Toru Takeo and Naomi Nakagata describe their superovulation results using young (4-weeks old) C57BL/6 female after envisaging a new priming protocol. The combined used of equine chorionic gonadotropin (eCG) and inhibin antiserum (IAS), in a protocol they call IASe treatment, significantly increased the number of oocytes obtained per C57BL/6 females. On average, more than 100 oocytes/female were obtained, about 3-4 times the number of oocytes regularly obtained by classical superovulation protocols. Thereafter, the authors tested the quality of these oocytes and used them for IVF, obtaining high fertilization rates (~90%), comparable to the high values regularly obtained with the new CARD methods these authors also devised recently, which have boosted the field of cryopreservation of mutant mice. Furthermore, the authors verified that the number of pups obtained after transferring all these embryos, obtained from IASe-derived oocytes and IVF into recipients, was also 2-3 times higher.
The IAS reagent used by Takeo & Nakagata is not yet commercially available. In the paper, the authors produced the IAS by themselves and titrated the product until finding the optimal dose required for maximum output. On the contrary, eCG is commercially available and is commonly used in all mouse reproductive biology and transgenic labs to promote follicle growth. Subsequent experiments will be needed to explore the validity of these results in other mouse strains and species. In addition, a commercial reliable and validated source of IAS will greatly facilitate the dissemination of this new ultra-superovulation method among the scientific community. It is also remarkable to note that the application of the IASe treatment will logically reduce the number of superovulated donor females required to obtain oocytes for cryopreservation/IVF purposes, as nicely demonstrated in this first publication, and, likely, for other aims (i.e. microinjection of DNA or RNA/genome editors to produce genetically altered mice).
Congratulations once again to Toru Takeo and Naomi Nakagata for these impressing results and for their new spectacular achievement in mouse reproductive biology!.