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Title page:
Can the location of a trophectoderm biopsy contribute to human blastocyst
development ?
Authors
Takano Tomoe, M.Sc. ,1) Funabiki Miyako, M.D., 1) Taguchi Sagiri, M.D., Ph.D., 1) Saji
Fumie, Ph.D. , 1) Amano Namiko, B.Sc. , 1) Young Louise Kate, B.Sc. , 1) and
Nakamura Yoshitaka, M.D. 1)
All authors address: 1) Oak Clinic, Osaka and Tokyo, Japan
2-7-9 Tamade-Nishi, Nishinari-ku, Osaka, 557-0045
Contact information for the corresponding author:
Takano Tomoe, M.Sc.,
Oak Clinic, Osaka and Tokyo, Japan
Address: 2-7-9 Tamade-Nishi, Nishinari-ku, Osaka, 557-0045
E-mail: takano_t@oakclinic-group.com
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Abstract
The influence of the location of a trophectoderm biopsy in human blastocysts on the
development of those blastocysts has not yet been investigated. In our prospective study
(n=92), our multivariate logistic regression analysis indicated that blastocoel
development was influenced by the location of the trophectoderm biopsy (p=0.049) and
by the type of human blastocyst used (fresh or thawed) (p=0.037), regardless of the
patient's age (p=0.507) and the number of days for the human blastocyst in the pre-
trophectoderm biopsy (p=0.239). Therefore, when a trophectoderm biopsy is close to the
inner cell mass (ICM) in human blastocysts, it improves the progress of blastocoel
development.
Clinical evidence suggests that the progress of blastocoel development is a predictor of
clinical outcomes after single blastocyst transfer. Therefore, when the trophectoderm
biopsy is done from near the ICM, improvement of clinical outcomes after single
blastocyst transfer may be expected.
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Introduction
Trophectoderm biopsy for human blastocysts is conducted for preimplantation genetic
screening (PGS) and/or preimplantation genetic diagnosis (PGD) in many in vitro
fertilization (IVF) clinics [1-3].
However, the influence of the location of a trophectoderm biopsy in human blastocysts
on the development of those blastocysts has not yet been investigated.
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Materials and Methods
Study design
The present study was an experimental study involving 92 patients (median age 34.3
years old) with infertility at our institute.
Discarded embryos used in the study were collected with the patients’ informed
consent and were cultured. They were either fresh or frozen-thawed.
The study protocol
Each patient was assigned to one of the following three treatment groups as follows
(Fig. 1).
Group A: location close to the inner cell mass (ICM) (n=29)
Group B: location distant from the ICM (n=32)
Group C: location between A and B (n=31)
The influence of the location of the trophectoderm biopsy within the human blastocysts
on the development of those blastocysts was compared between pre- and post-
trophectoderm biopsies, according to the Gardner and Schoolcraft scoring system 4.
Human blastocyst development was scored by blastocoel stage (from 1 to 6: highest score
is 6), ICM grade (highest score A, followed by B and C) and trophectoderm (TE) grade
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(highest score A, followed by B and C) [4]. Higher scores were considered improvements
[4]. Two clinical embryologists evaluated the human blastocyst development
.
The time between the post-trophectoderm biopsies and the evaluation of the
development of the human blastocysts was 24 hours.
Institutional Review Board (IRB) approval
This study was approved by the IRB of Oak Clinic, Osaka and Tokyo, Japan (the
approval number is 2013081904).
The patients provided informed consent.
Statistical analyses
Statistical tests were performed using Dr. SPSS II for Windows (SPSS Japan, Inc.,
Tokyo), and significance was defined as p<0.05. Statistical analyses of group differences
were analyzed using Fisher’s exact test.
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Results
The rate of blastocoels that showed developmental progress
According to the Gardner and Schoolcraft scoring system [4], degree (one up to six) of
expansion of the blastocoel indicates progress of blastocoel development. The rate of
blastocoels that showed developmental progress in Group A was significantly higher
(p=0.024, Fisher's exact test) than in Group B: 25/29 (86.2%) versus 19/32 (59.4%),
respectively (Fig.2). The location of the trophectoderm biopsy in the human blastocysts
did not change the trophectoderm and ICM grading.
Multivariate logistic regression analysis
Multivariate logistic regression analysis (Table 1) indicated that blastocoel
development was influenced by the location of the trophectoderm biopsy (p=0.049) and
by the type of human blastocyst used (fresh or thawed) (p=0.037), regardless of the
patient's age (p=0.507) and the number of days for the human blastocyst in the pre-
trophectoderm biopsy (p=0.239).
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was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made
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T value
P value
95%CI
(Low)
95%CI
(High)
Patient's age
-0.664
0.507
-0.027
0.013
The number of days for the human blastocyst
in the pre-trophectoderm biopsy
-1.185
0.239
-0.260
0.065
The type of human blastocyst used (fresh or
thawed)
2.112
0.037
0.011
0.392
The location of the trophectoderm biopsy
1.99
0.049
0.0002
0.228
Table 1: Multivariate logistic regression analysis.
95% CI means 95 % confidence interval.
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Discussion
The present study is the first to report that when a trophectoderm biopsy is close to the
ICM in human blastocysts, it improves the progress of blastocoel development.
Clinical evidence suggests that the progress of blastocoel development is a predictor of
clinical outcomes after single blastocyst transfer [5-8]. Therefore, when the
trophectoderm biopsy is done from near the ICM, improvement of clinical outcomes after
single blastocyst transfer may be expected.
However, when a trophectoderm biopsy is close to the ICM in human blastocysts, the
risk is still unclear. Therefore, the risk and benefit in the clinical settings should be
evaluated in the near future.
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Acknowledgements
We are grateful to the physicians, nurses and clinical embryologists for their assistance
with the design of this study and/or the experiments performed at our clinic.
Author contributions
T.T.: Conception and design of the study, provision of the study materials, collection
and/or assembly of the data, analysis and interpretation of the data, writing of the
manuscript, and final approval of the manuscript.
S.T.: Provision of the study materials, collection and/or assembly of the data, analysis
and interpretation of the data and final approval of the manuscript.
M.F.: Provision of the study materials, collection and/or assembly of the data, analysis
and interpretation of the data and final approval of the manuscript.
F.S.: Provision of the study materials, collection and/or assembly of the data and final
approval of the manuscript.
N.A.: Provision of the study materials, collection and/or assembly of the data and final
approval of the manuscript.
K. L.Y.: Provision of the study materials, collection and/or assembly of the data and final
approval of the manuscript.
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Y.N.: Analysis and interpretation of the data, writing of the manuscript, and final
approval of the manuscript.
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was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made
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Figure legends
Fig. 1: The location of a trophectoderm biopsy.
Fig. 2: The rate of blastocoels that showed developmental progress.
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was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made
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