Controlled Ovarian Stimulation of Rhesus Monkeys Using Macaque Recombinant Gonadotropins. (2008)

Nonprimate or human recombinant gonadotropins commonly used in controlled ovarian stimulation protocols are antigenic in nonhuman primates (NHPs), thus limiting the number of protocols performed before antibody generation. In an effort to overcome this limitation, we assessed the effectiveness of two recombinant NHP (cynomolgus macaque) gonadotropins, follicle stimulating hormone (FSH) and luteinizing hormone (LH) for inducing multiple follicle development in rhesus monkey ovaries. Hormones were provided by the National Hormone & Peptide Program (Torrance, CA). Eighteen adult females with regular menstrual cycles were selected and each animal received one of the two stimulation regimens: (#1) cynomolgus FSH (n=8; 30 IU, im, BID) or (#2) cynomolgus FSH + cynomolgus LH (n=10; 30 IU, im, BID). In addition, all animals received GnRH agonist (Acyline; NIH/NICHD, Bethesda, MD; 0.075 mg/kg body weight, sc) during the stimulation period and human chorionic gonadotropin (hCG; Serono, Randolph, MA; 1,000 IU, im) 36 hours prior to laparoscopic follicle aspiration and oocyte retrieval. Serum estradiol (E2) and progesterone (P4) measurements along with ultrasonographic scans were performed to determine follicular response to the exogenous gonadotropins. The length of the stimulation required to induce multiple follicle development was statistically different (P < 0.01) between treatment groups #1 and #2, with animals taking approximately 11 days and 8 days to respond to the exogenous hormones, respectively. Also, successful ovarian response to the two different stimulation regimens (as defined by ovaries with enlarged follicles ≥ 3-4 mm in diameter following hormone treatment) tended to vary per treatment (P > 0.1) with 63% (5/8) of animals responding to treatment #1 and 80% (8/10) responding to treatment #2. Peak E2 levels for treatment #1 (290 pg/ml) typically were lower than for treatment #2 (603 pg/ml; P = 0.08). P4 levels generally remained <0.2 ng/ml during the follicular stimulation period in both groups. In terms of oocyte recovery, a mean of 30 and 22 oocytes were collected from stimulation regimens #1 and #2, of which 34% and 40%, respectively, were at the metaphase II (MII) stage. Fertilization was achieved in approximately 86% and 67% of MII oocytes, while blastocysts developed from 73% and 61% of fertilized oocytes from treatment groups #1 and #2, respectively. No statistical differences (P > 0.1) were detected in the number of oocytes recovered or fertilized, or in the rate of blastocyst development. Our data demonstrate that ovarian stimulation regimens involving NHP recombinant gonadotropins can be used to successfully stimulate multiple follicular development in rhesus macaques for the recovery of meiotically mature oocytes. Cynomolgus FSH alone supports follicle and oocyte maturation; however, the addition of LH to the stimulation protocol shortened the stimulation period and increased follicular steroidogenesis, while still permitting the recovery of a usable number of developmentally competent monkey oocytes suitable for fertilization and blastocyst production in vitro. Supported by HD18185 ART Core; RR00163 ART-ESC Core.