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Opportunities and Limits of Conventional IVF: History
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Contributor:
Martina Balli
, Anna Cecchele ,
Valerio Pisaturo
,
Sofia Makieva
,
Giorgia Carullo
, Edgardo Somigliana , Alessio Paffoni , Paola Vigano’

Conventional IVF (c-IVF) is one of the most practiced assisted reproductive technology (ART) approaches used worldwide. However, in the last years, the number of c-IVF procedures has dropped dramatically in favor of intracytoplasmic sperm injection (ICSI) in cases of non-male-related infertility. The advantages and disadvantages associated with c-IVF, highlighting the essential steps governing its success, its limitations, the methodology differences among laboratories and the technical progress were outlined. A framework for a better understanding of opportunities associated with human c-IVF and for best practice guidelines applicability in the reproductive medicine field was introduced.

  • infertility
  • IVF
  • reproduction

1. Timing of Insemination from Oocyte Retrieval

The debate regarding the effect of the timing of insemination after oocyte retrieval started in the 1980s, when three different groups demonstrated better fertilization rates and higher embryo quality when oocytes were inseminated after a pre-incubation period of 3–5.5 h after retrieval [1][2][3][4]. In the same years, the group of Fish and coworkers showed that different pre-insemination intervals (within 9 h after oocyte retrieval) did not affect fertilization or pregnancy rates [4]. More recent studies focused on the impact of the pre-incubation period on the fertilization rate were similarly not concordant. Ho et al. reported significantly better results by performing the insemination in a time window ranging from 2.5 to 5.5 h after oocytes retrieval. Specifically, they analyzed the fertilization rate at <2.5 h, <3.5 h, <4.5 h, ≤5.5 h and >5.5 h after oocyte retrieval and observed fertilization rates of 67.9%, 80.5%, 82.0%, 84.5% and 73.0%, respectively. They obtained statistically significant data when the insemination was performed <2.5 h and 5.5 h after oocyte retrieval (p < 0.001) [5]. In contrast, Jacobs and colleagues demonstrated different results analyzing the fertilization rate, embryo quality, implantation rate, abortion and ongoing pregnancy when inseminations were performed 1–7 h after oocyte retrieval. No statistically significant differences in c-IVF outcomes performed in different time intervals were observed, suggesting that early insemination could be performed without reservation [6]. Esiso and colleagues divided the time interval between oocyte retrieval and insemination into eight categories: 0 (0–<0.5 h), 1 (0.5–<1.5 h), 2 (1.5–<2.5 h), 3 (2.5–<3.5 h), 4 (3.5–<4.5 h), 5 (4.5–<5.5 h), 6 (5.5–<6.5 h) and 7 (6.5–<8 h). The relative number of oocytes retrieved in each category was n = 586, n = 1594, n = 1644, n = 1796, n = 1836, n = 1351, n = 641 and n = 127, respectively. Considering only the c-IVF outcome, they had optimal results when the insemination was performed between 1.5 h and 6 h after oocyte retrieval. When performed prior to 1.5 h, the detrimental effects of insemination on the fertilization rate were only moderate, without affecting blastulation and pregnancy rates [7]. Overall, these studies demonstrate the existence of an optimum time range for more successful c-IVF that should be performed between 3 and 6 h after oocyte retrieval. Of note, the time elapsed from ovulation trigger and oocyte retrieval (generally 34–36 h) should be taken into account when evaluating the proper timing of insemination.

2. Timing of Sperm-Cumulus Co-Incubation

The standard human c-IVF method involves overnight insemination of cumulus-intact oocytes with a defined range of spermatozoa/mL, followed by a fertilization assessment in the next morning [8]. It has been, however, suggested that extended gametes co-incubation may lead to unsuccessful c-IVF due to the production of high concentrations of reactive oxygen species (ROS), potentially deleterious for oocyte and embryo quality [9][10][11][12]. Therefore, to prevent unfavorable effects on oocytes and related embryos from high ROS exposure, a shorter incubation of gametes has been proposed. Studies addressing the comparison between short gametes co-incubation to standard overnight IVF (16–18 h) are listed in Table 1 [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32]. Yet in 1996, Gianaroli et al. reported that a short gamete co-incubation (1 h) led to an increased rate of oocyte fertilization and embryo viability, suggesting that prolonged exposure of oocytes to elevated concentrations of sperm cells may negatively influence early embryo development [13]. In accordance, Le Bras and colleagues demonstrated that short gamete co-incubation period (2 h) leads to higher embryo quality, with a percentage of fragmentation lower than 25%, and, most importantly, to a significant increase in clinical pregnancy after a fresh embryo transfer compared to standard overnight insemination (16–18 h) [14]. Other studies reported that a shorter oocyte-spermatozoa incubation time is associated with an enhanced embryo quality and could prevent total fertilization failure (TTF) [15][16]. Conversely, in a prospective study, Barraud-Lange et al. evaluated the effects of a short gamete co-incubation (1 h) on fertilization rate and embryo quality of sibling oocytes, showing a decreased fertilization rate and comparable embryo quality compared to the standard overnight insemination method [17]. The meta-analysis from Zhang et al., published in 2013, revealed that reduced gamete co-incubation time is associated with beneficial outcomes, including significantly increased clinical pregnancy rate (Pooled Risk Ratio [RR]: 1.84, 95% confidence interval (CI) 1.24–2.73), ongoing pregnancy rate (RR: 1.73, 95% CI: 1.27–2.33) and implantation rate (RR: 1.80, 95% CI: 1.43–2.26) compared to c-IVF, with no significant differences in fertilization rates, embryo quality and polyspermy rate (RR: 0.98, 95% CI: 0.93–1.02; RR: 1.24, 95% CI: 1.0–1.53; RR: 0.84, 95% CI: 0.7–1.01, respectively) [18]. A recent randomized study of n= 320 infertile women, evaluated the beneficial influence of short gamete co-incubation in terms of live birth rate. Here, oocytes of patients randomized to the short co-incubation period group (3–4 h, n = 160) and to the conventional co-incubation timing (20 h, n = 160) were inseminated with ~20,000–30,000 motile spermatozoa/oocyte. Contrarily to other studies, no statistically significant difference in terms of live birth rate, clinical pregnancy, miscarriage and implantation rates was reported between the short-time and standard overnight insemination groups [19]. Overall, evidence on which is the best timing of sperm-egg co-incubation in c-IVF requires more consolidation.
Table 1. Results deriving from the comparison between different incubation intervals of spermatozoa and oocytes in in vitro fertilization procedure.
Authors, Year Interval of
Co-Incubation		 Fertilization Rate (FR) in Short IVF Clinical Pregnancy Rate (CPR) in Short IVF Implantation Rate (IP) in Short IVF
Gianaroli et al., 1996 [13] 1 h vs. overnight Improved Improved Improved
Quinn et al., 1998 [20] 1 h vs. overnight Unchanged Improved Improved
Coskun et al., 1998 [21] 1 h vs. overnight Unchanged Not assessed Not assessed
Dirnfeld et al., 1999 [22] 1 h vs. overnight Unchanged Improved Improved
Lin et al., 2000 [23] 1–3 h vs. overnight Unchanged Not assessed Not assessed
Swenson et al., 2000 [24] 2 h vs. overnight Not assessed Worsened Unchanged
Boone et al., 2001 [25] 3 h vs. overnight Worsened Not assessed Not assessed
Lundqvist et al., 2001 [26] 2 h vs. overnight Worsened Unchanged Unchanged
Dirnfeld et al., 2003 [12] 1 h vs. overnight Unchanged Not assessed Not assessed
Kattera et al., 2003 [27] 2 h vs. overnight Unchanged Improved Improved
Barraud-Lange et al., 2008 [28] 1 h vs. overnight Worsened Not assessed Not assessed
Xiong et al., 2009 [17] 1–6 h vs. overnight Unchanged Unchanged Not assessed
Dai et al., 2012 [29] 1–4 h vs. overnight Unchanged Unchanged Unchanged
Huang et al., 2013 [30] 1–4 h vs. overnight Not assessed Improved Not assessed
Zhang et al., 2013 [31] 1–6 h vs. overnight Unchanged Improved Improved
Li et al., 2016 [10] 2 h vs. overnight Unchanged Improved Improved
Le Bras et al., 2017 [18] 2 h vs. overnight Worsened Improved Improved
He et al., 2018 [32] 4/6 h vs. overnight Worsened Unchanged Unchanged
Chen et al., 2019 [14] 3/4 h vs. overnight Unchanged Unchanged Unchanged
Kong et al., 2021 [15] 4 h vs. overnight Unchanged Unchanged Not assessed

3. Oxygen Tension

Embryo development depends on a variety of factors, and among others, oxygen tension represents one of the key decisive parameters to ensure proper embryogenesis [19]. Mammalian development is characterized by low concentration of oxygen in both fallopian tubes and uterus, ranging from 5 to 7% in the former and decreasing to 2% in the latter [16]. Therefore, in order to support proper embryo development, it may be crucial to mimic the low level of oxygen tension (5%) present in the in vivo developmental environment. Interestingly, several studies reported that successful human embryo culture, in terms of embryo quality and blastulation rate, occurs under hypoxic conditions (5% oxygen tension). Moreover, the rate of implantation, pregnancy, good-quality embryos for transfer and live birth significantly increases under hypoxia culture conditions rather than with atmospheric oxygen levels [33][34][35][36][37]. The oxidative stress resulting from high oxygen concentration culture conditions may severely affect embryo quality, decreasing its implantation potential and, as a consequence, the pregnancy rate [34][36][38]. Moreover, embryos exposed to ROS are prone to DNA damage and mitochondrial alterations, leading to activation of the apoptotic mechanism [39]. Data obtained from a meta-analysis showed a notable improvement on live birth rate following embryo culture in low oxygen concentration. The rate of live births was improved up to 43% by lowering the oxygen concentration during embryo development [40]. Accordingly, recommendations provided from the latest ESHRE guidelines suggest the use of low oxygen concentration for embryo culture [41]. Nonetheless, the oxygen tension used in the culture system has ample differences among ART laboratories worldwide [42]. Notably, the impact of oxygen tension on results of ICSI versus c-IVF in relation to stage-specific sensitivity is unclear. Most of the papers on this topic do not divide the results according to the two strategies. In a prospective randomized sibling-oocyte study, Guo et al. evaluated the impact of different oxygen concentrations (20% versus 5%) on fertilization rates in c-IVF cycles. A total of n = 1254 oocytes were randomly assigned to 20% or 5% oxygen tension culture conditions on the retrieval day and then treated with c-IVF. The two groups did not show differences in fertilization rate, suggesting that at this stage of development, different oxygen tensions may not influence the process of fertilization. However, oocytes cultured at 5% oxygen gave rise to an increased number of optimal embryos on day 3 (72.4% vs. 64.2%, respectively, p = 0.018) and higher blastocyst formation rate (64.5% vs. 52.9%, respectively, p = 0.009) compared to the 20% group. Moreover, the use of low oxygen tension resulted in a more favorable clinical pregnancy and implantation rates compared with atmospheric oxygen [43]. In a total of n = 402 ART cycles, Guarneri et al. specifically evaluated the use of two different oxygen concentrations (atmospheric versus low oxygen) during oocyte culture from recovery until decumulation on day 1, followed by use of low oxygen concentration (5%) until transfer. Interestingly, cumulus-intact oocytes cultured in atmospheric oxygen tension for ~20 h for c-IVF resulted in a comparable number of transferred/vitrified embryos from the inseminated oocytes, cumulative clinical pregnancy rate and cumulative live birth rate per cycle compared to the oocytes cultured under 5% oxygen level from gamete retrieval to embryo transfer [44]. Although evidence-based data strongly indicate that culturing embryos in low oxygen concentration improves embryo utilization rate and increases the chance of pregnancy [41][45], the potential antioxidant activity of the cumulus cells present during the first step of c-IVF needs to be further investigated.

This entry is adapted from the peer-reviewed paper 10.3390/jcm11195722

References

  1. Trounson, A.O.; Mohr, L.R.; Wood, C.; Leeton, J.F. Effect of delayed insemination on in-vitro fertilization, culture and transfer of human embryos. J. Reprod. Fertil. 1982, 64, 285–294.
  2. Harrison, K.L.; Wilson, L.M.; Breen, T.M.; Pope, A.K.; Cummins, J.M.; Hennessey, J.F. Fertilization of human oocytes in relation to varying delay before insemination. Fertil. Steril. 1988, 50, 294–297.
  3. Khan, I.; Staessen, C.; Van den Abbeel, E.; Camus, M.; Wisanto, A.; Smitz, J.; Devroey, P.; Van Steirteghem, A.C. Time of insemination and its effect on in-vitro fertilization, cleavage and pregnancy rates in GnRH agonist/HMG-stimulated cycles. Hum. Reprod. 1989, 4, 921–926.
  4. Fisch, B.; Kaplan-Kraicer, R.; Amit, S.; Ovadia, J.; Tadir, Y. The effect of preinsemination interval upon fertilization of human oocytes in vitro. Hum. Reprod. 1989, 4, 954–956.
  5. Ho, J.Y.; Chen, M.J.; Yi, Y.C.; Guu, H.F.; Ho, E.S. The effect of preincubation period of oocytes on nuclear maturity, fertilization rate, embryo quality, and pregnancy outcome in IVF and ICSI. J. Assist. Reprod. Genet. 2003, 20, 358–364.
  6. Jacobs, M.; Stolwijk, A.M.; Wetzels, A.M. The effect of insemination/injection time on the results of IVF and ICSI. Hum. Reprod. 2001, 16, 708–713.
  7. Esiso, F.M.; Cunningham, D.; Lai, F.; Garcia, D.; Barrett, C.B.; Thornton, K.; Sakkas, D. The effect of rapid and delayed insemination on reproductive outcome in conventional insemination and intracytoplasmic sperm injection in vitro fertilization cycles. J. Assist. Reprod. Genet. 2021, 38, 2697–2706.
  8. Barrie, A.; Smith, R.; Campbell, A.; Fishel, S. Optimisation of the timing of fertilisation assessment for oocytes cultured in standard incubation: Lessons learnt from time-lapse imaging of 78 348 embryos. Hum. Reprod. 2021, 36, 2840–2847.
  9. Lushchak, V.I. Free radicals, reactive oxygen species, oxidative stress and its classification. Chem. Biol. Interact. 2014, 224, 164–175.
  10. Li, R.Q.; Ouyang, N.Y.; Ou, S.B.; Ni, R.M.; Mai, M.Q.; Zhang, Q.X.; Yang, D.Z.; Wang, W.J. Does reducing gamete co-incubation time improve clinical outcomes: A retrospective study. J. Assist. Reprod. Genet. 2016, 33, 33–38.
  11. Anzalone, D.A.; Palazzese, L.; Czernik, M.; Sabatucci, A.; Valbonetti, L.; Capra, E.; Loi, P. Controlled spermatozoa-oocyte interaction improves embryo quality in sheep. Sci. Rep. 2021, 11, 22629.
  12. Dirnfeld, M.; Shiloh, H.; Bider, D.; Harari, E.; Koifman, M.; Lahav-Baratz, S.; Abramovici, H. A prospective randomized controlled study of the effect of short coincubation of gametes during insemination on zona pellucida thickness. Gynecol. Endocrinol. 2003, 17, 397–403.
  13. Gianaroli, L.; Fiorentino, A.; Magli, M.C.; Ferraretti, A.P.; Montanaro, N. Prolonged sperm-oocyte exposure and high sperm concentration affect human embryo viability and pregnancy rate. Hum. Reprod. 1996, 11, 2507–2511.
  14. Chen, Z.Q.; Wang, Y.; Ng, E.H.Y.; Zhao, M.; Pan, J.P.; Wu, H.X.; Teng, X.M. A randomized triple blind controlled trial comparing the live birth rate of IVF following brief incubation versus standard incubation of gametes. Hum. Reprod. 2019, 34, 100–108.
  15. Kong, P.; Yin, M.; Tang, C.; Zhu, X.; Bukulmez, O.; Chen, M.; Teng, X. Effects of Early Cumulus Cell Removal on Treatment Outcomes in Patients Undergoing In Vitro Fertilization: A Retrospective Cohort Study. Front. Endocrinol. 2021, 12, 669507.
  16. De Munck, N.; Janssens, R.; Segers, I.; Tournaye, H.; Van de Velde, H.; Verheyen, G. Influence of ultra-low oxygen (2%) tension on in-vitro human embryo development. Hum. Reprod. 2019, 34, 228–234.
  17. Xiong, S.; Han, W.; Liu, J.X.; Zhang, X.D.; Liu, W.W.; Liu, H.; Huang, G.N. Effects of cumulus cells removal after 6 h co-incubation of gametes on the outcomes of human IVF. J. Assist. Reprod. Genet. 2011, 28, 1205–1211.
  18. Le Bras, A.; Hesters, L.; Gallot, V.; Tallet, C.; Tachdjian, G.; Frydman, N. Shortening gametes co-incubation time improves live birth rate for couples with a history of fragmented embryos. Syst. Biol. Reprod. Med. 2017, 63, 331–337.
  19. Fathollahipour, S.; Patil, P.S.; Leipzig, N.D. Oxygen Regulation in Development: Lessons from Embryogenesis towards Tissue Engineering. Cells Tissues Organs 2018, 205, 350–371.
  20. Quinn, P.; Lydic, M.L.; Ho, M.; Bastuba, M.; Hendee, F.; Brody, S.A. Confirmation of the beneficial effects of brief coincubation of gametes in human in vitro fertilization. Fertil. Steril. 1998, 69, 399–402.
  21. Coskun, S.; Roca, G.L.; Elnour, A.M.; al Mayman, H.; Hollanders, J.M.; Jaroudi, K.A. Effects of reducing insemination time in human in vitro fertilization and embryo development by using sibling oocytes. J. Assist. Reprod. Genet. 1998, 15, 605–608.
  22. Dirnfeld, M.; Bider, D.; Koifman, M.; Calderon, I.; Abramovici, H. Shortened exposure of oocytes to spermatozoa improves in-vitro fertilization outcome: A prospective, randomized, controlled study. Hum. Reprod. 1999, 14, 2562–2564.
  23. Lin, S.P.; Lee, R.K.; Su, J.T.; Lin, M.H.; Hwu, Y.M. The effects of brief gamete co-incubation in human in vitro fertilization. J Assist Reprod Genet. 2000, 17, 344–348.
  24. Swenson, K.; Check, J.H.; Summers-Chase, D.; Choe, J.K.; Check, M.L. A randomized study comparing the effect of standard versus short incubation of sperm and oocyte on subsequent pregnancy and implantation rates following in vitro fertilization embryo transfer. Arch. Androl. 2000, 45, 73–76.
  25. Boone, W.R.; Johnson, J.E. Extending the coincubation time of gametes improves in vitro fertilization. J. Assist. Reprod. Genet. 2001, 18, 18–20.
  26. Lundqvist, M.; Johansson, U.; Lundkvist, O.; Milton, K.; Westin, C.; Simberg, N. Reducing the time of co-incubation of gametes in human in-vitro fertilization has no beneficial effects. Reprod. Biomed. Online. 2001, 3, 21–24.
  27. Kattera, S.; Chen, C. Short coincubation of gametes in in vitro fertilization improves implantation and pregnancy rates: A prospective, randomized, controlled study. Fertil. Steril. 2003, 80, 1017–1021.
  28. Barraud-Lange, V.; Sifer, C.; Pocaté, K.; Ziyyat, A.; Martin-Pont, B.; Porcher, R.; Hugues, J.N.; Wolf, J.P. Short gamete co-incubation during in vitro fertilization decreases the fertilization rate and does not improve embryo quality: A prospective auto controlled study. J. Assist. Reprod. Genet. 2008, 25, 305–310.
  29. Dai, S.J.; Qiao, Y.H.; Jin, H.X.; Xin, Z.M.; Su, Y.C.; Sun, Y.P.; Chian, R.C. Effect of coincubation time of sperm-oocytes on fertilization, embryonic development, and subsequent pregnancy outcome. Syst. Biol. Reprod. Med. 2012, 58, 348–353.
  30. Huang, Z.; Li, J.; Wang, L.; Yan, J.; Shi, Y.; Li, S. Brief co-incubation of sperm and oocytes for in vitro fertilization techniques. Cochrane Database Syst. Rev. 2013, CD009391.
  31. Zhang, X.D.; Liu, J.X.; Liu, W.W.; Gao, Y.; Han, W.; Xiong, S.; Wu, L.H.; Huang, G.N. Time of insemination culture and outcomes of in vitro fertilization: A systematic review and meta-analysis. Hum. Reprod. Update 2013, 19, 685–695.
  32. He, Y.; Liu, H.; Zheng, H.; Li, L.; Fu, X.; Liu, J. Effect of early cumulus cells removal and early rescue ICSI on pregnancy outcomes in high-risk patients of fertilization failure. Gynecol. Endocrinol. 2018, 34, 689–693.
  33. Steptoe, P.C.; Edwards, R.G.; Purdy, J.M. Human blastocysts grown in culture. Nature 1971, 229, 132–133.
  34. Waldenström, U.; Engström, A.B.; Hellberg, D.; Nilsson, S. Low-oxygen compared with high-oxygen atmosphere in blastocyst culture, a prospective randomized study. Fertil. Steril. 2009, 91, 2461–2465.
  35. Kasterstein, E.; Strassburger, D.; Komarovsky, D.; Bern, O.; Komsky, A.; Raziel, A.; Friedler, S.; Ron-El, R. The effect of two distinct levels of oxygen concentration on embryo development in a sibling oocyte study. J. Assist. Reprod. Genet. 2013, 30, 1073–1079.
  36. Sciorio, R.; Smith, G.D. Embryo culture at a reduced oxygen concentration of 5%: A mini review. Zygote 2019, 27, 355–361.
  37. Kea, B.; Gebhardt, J.; Watt, J.; Westphal, L.M.; Lathi, R.B.; Milki, A.A.; Behr, B. Effect of reduced oxygen concentrations on the outcome of in vitro fertilization. Fertil. Steril. 2007, 87, 213–216.
  38. Kirkegaard, K.; Hindkjaer, J.J.; Ingerslev, H.J. Effect of oxygen concentration on human embryo development evaluated by time-lapse monitoring. Fertil. Steril. 2013, 99, 738–744.
  39. May-Panloup, P.; Boguenet, M.; Hachem, H.E.; Bouet, P.E.; Reynier, P. Embryo and Its Mitochondria. Antioxidants 2021, 10, 139.
  40. Bontekoe, S.; Mantikou, E.; van Wely, M.; Seshadri, S.; Repping, S.; Mastenbroek, S. Low oxygen concentrations for embryo culture in assisted reproductive technologies. Cochrane Database Syst. Rev. 2012.
  41. ESHRE Guideline Group on Good Practice in IVF Labs; De los Santos, M.J.; Apter, S.; Coticchio, G.; Debrock, S.; Lundin, K.; Plancha, C.E.; Prados, F.; Rienzi, L.; Verheyen, G.; et al. Revised guidelines for good practice in IVF laboratories (2015). Hum. Reprod. 2016, 31, 685–686.
  42. Christianson, M.S.; Zhao, Y.; Shoham, G.; Granot, I.; Safran, A.; Khafagy, A.; Leong, M.; Shoham, Z. Embryo catheter loading and embryo culture techniques: Results of a worldwide Web-based survey. J. Assist. Reprod. Genet. 2014, 31, 1029–1036.
  43. Guo, N.; Li, Y.; Ai, J.; Gu, L.; Chen, W.; Liu, Q. Two different concentrations of oxygen for culturing precompaction stage embryos on human embryo development competence: A prospective randomized sibling-oocyte study. Int. J. Clin. Exp. Pathol. 2014, 7, 6191–6198.
  44. Guarneri, C.; Restelli, L.; Mangiarini, A.; Ferrari, S.; Somigliana, E.; Paffoni, A. Can we use incubators with atmospheric oxygen tension in the first phase of in vitro fertilization? A retrospective analysis. J. Assist. Reprod. Genet. 2015, 32, 77–82.
  45. Mantikou, E.; Bontekoe, S.; van Wely, M.; Seshadri, S.; Repping, S.; Mastenbroek, S. Low oxygen concentrations for embryo culture in assisted reproductive technologies. Hum. Reprod. Update 2013, 19, 209.
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