In vivo maturation of immature oocytes in stimulated cycles

Abstract

To the Editor: Johnson et al.'s (1Johnson J.E. Lee Higdon H.L. Boone W.R. Effect of human granulose cell co-culture using standard culture media on the maturation and fertilization potential of immature oocytes.Fertil Steril. 2008; 90: 1674-1679Abstract Full Text Full Text PDF PubMed Scopus (29) Google Scholar) efforts to rescue and utilize immature oocytes generated during ovarian stimulation cycles, which would otherwise be wasted, are commendable. This author's experience in a similar endeavor (2Ali J. Joshi H.N. Al-Badr M. Shahata M.A.M. Abdulkader A. Al-Natsha S. Flamerzi M. et al.Subzonal insemination of immature oocytes generated during intracytoplasmic injection cycles.Med Sci Res (UK). 1998; 26: 389-391Google Scholar) suggests that ovarian stimulation regimens may generate approximately 20% immature oocytes (1Johnson J.E. Lee Higdon H.L. Boone W.R. Effect of human granulose cell co-culture using standard culture media on the maturation and fertilization potential of immature oocytes.Fertil Steril. 2008; 90: 1674-1679Abstract Full Text Full Text PDF PubMed Scopus (29) Google Scholar, 2Ali J. Joshi H.N. Al-Badr M. Shahata M.A.M. Abdulkader A. Al-Natsha S. Flamerzi M. et al.Subzonal insemination of immature oocytes generated during intracytoplasmic injection cycles.Med Sci Res (UK). 1998; 26: 389-391Google Scholar), which is a significant loss if efforts are not made to rescue and utilize them. The poor maturation rate of germinal vesicle–stage (GV) oocytes reported by Johnson et al. with cumulus cell (CC) but not granulosa cell (GC) coculture was probably because 24 hours is insufficient to attain maturity. Germinal vesicle–stage oocytes may take up to 48 hours to mature even in specialized in vivo maturation (IVM) medium (MediCult, Jyllinge, Denmark) containing FSH, hCG, and follicular fluid with CC coculture (3Zhu X.M. Zhu Y.M. Xu C.M. Qian Y.L. Jin F. Huang H.F. Autologous mature follicular fluid: its role in in vitro maturation of human cumulus-removed oocytes.Fertil Steril. 2008; 90: 1094-1102Abstract Full Text Full Text PDF PubMed Scopus (11) Google Scholar). Johnson et al.'s findings of poor outcome after IVM led them to conclude that their extended culture techniques with and without CC in standard medium is inefficient and a waste of resources. This author's preliminary observations suggest a high level of maturity of metaphase I oocytes (12 of 12) in ultra-microdrop (UMD) culture of approximately 1.5–2 μL (4Ali J. Continuous ultra micro-drop (cUMD) culture yields higher pregnancy and implantation rates than either larger-drop culture or fresh-medium replacement.Clin Embryol. 2004; 7: 1-23Google Scholar) within 24 hours in standard medium (Cleavage Medium; Cook IVF, Limerick, Ireland). Germinal vesicle–stage oocytes that matured under similar conditions were somewhat lower at 24 hours (39.4%, 13 of 33) but improved marginally by 48 hours of IVM (48.5%, 17 of 30). Under similar conditions of IVM but with autologous GC and/or CC coculture in 2.5–3.0 μL of UMD culture, a higher proportion of GV oocytes attained maturity at 24 hours (54.5%, 6 of 11; P=.5981) and 48 hours (81.8%, 9 of 11; P=.1138). Paracrine factors released into the UMD coculture milieu by the egg, GC, and CC concentrated within the ultra-volume of the culture system may be involved in the maturation of GV oocytes. This author's findings in UMD + GC + CC coculture were somewhat higher at 24 hours (54.5% vs. 23.8%) but similar at 48 hours of IVM (81.8% vs. 85.7%) to that obtained with specialized IVM medium + CC + follicular fluid + FSH + hCG supplementation (3Zhu X.M. Zhu Y.M. Xu C.M. Qian Y.L. Jin F. Huang H.F. Autologous mature follicular fluid: its role in in vitro maturation of human cumulus-removed oocytes.Fertil Steril. 2008; 90: 1094-1102Abstract Full Text Full Text PDF PubMed Scopus (11) Google Scholar), but cytoplasmic maturity in the former remains to be elucidated. Although these data are preliminary, it seems reasonable to suggest that efforts to rescue immature oocytes from stimulated cycles be continued. Reply of the Author: In vivo maturation of immature oocytes in stimulated cyclesFertility and SterilityVol. 92Issue 1PreviewWe would like to thank Dr. Ali for his interest in our research and appreciate his supportive comments. Our goal in attempting to mature metaphase I and germinal vesicle–stage oocytes was to decrease oocyte wastage and, hopefully, provide more viable embryos for our IVF patients' use for ET or cryopreservation. Although our process of using standard culture media proved inefficient in these respects (few immature oocytes matured, fertilized, and then cleaved to embryos), it is heartening to know that, as we theorized, the use of specialized culture medium (such as medium supplemented with autologous granulosa cells and mature follicular fluid) and techniques (such as continuous ultra-microdrop culture) can improve the nuclear maturation rates of immature oocytes. Full-Text PDF