Impact of elemental iron on human spermatozoa and mouse embryonic development in vitro in a defined synthetic protein-free culture system / Safaa Mahmoud Naes
The element iron is essential for life and plays a number of key roles in biological processes and it is involved in cell development, some of which are intimately related to spermatogenesis and spermatozoa metabolism. Iron and its compounds within certain limits are not fundamentally toxic for t...
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| Format: | Thesis |
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2018
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| Online Access: | http://studentsrepo.um.edu.my/11462/ http://studentsrepo.um.edu.my/11462/4/safaa.pdf |
| Summary: | The element iron is essential for life and plays a number of key roles in biological
processes and it is involved in cell development, some of which are intimately related to
spermatogenesis and spermatozoa metabolism. Iron and its compounds within certain
limits are not fundamentally toxic for the human organisms. However, the role of iron in
infertility has not been widely investigated. Infertility, which known as a failure to
achieve conception after one year of regular unprotected sexual intercourse, affects 10–
15% of couples and approximately 80 million couples worldwide. The common causes
of infertility include male factors, female factors, and unexplained causes. The rate of
male factors is 30% to 40%, female factors 40%, and unexplained causes 10% of
infertility cases.
This study aims to ascertain the optimal level of iron needed for optimal embryonic
development (Spermatozoa and embryos) in protein free culture media, and toxic levels
to enable its application in assisted reproductive technologies to help increase the
pregnancy rates. Different levels of ferric iron concentrations were prepared using
HEPES and protein- free culture media. The levels of ferric iron investigated closely
resembled the normal range for human plasma iron (0.6-1.7 µg/ml). These levels were
investigated to determine the optimal and tolerance levels of iron for human
spermatozoa. Ferric chloride was used as source of iron in the HEPES-buffered
synthetic protein-free medium. Normozoospermic semen samples (n=24) were
incubated with different concentrations of iron (0.5, 1, 1.5, 2, 4, 8, 12, and 16 µg/ml) in
HEPES buffered protein-free culture medium at room temperature for 1hr and 20hrs.
Motility and vitality of spermatozoa were measured according to WHO Manual 2010.
Spermatozoa activity and sperm DNA integrity were evaluated at room temperature at
1hr and 20hrs. 2.0 µg/ml (35.8 µM) of ferric iron was the optimal level of ferric iron
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with range of tolerance levels (0.5- 2 µg/ml) which appeared beneficial for spermatozoa
motility at 1hr and up to 20hrs. Levels above 4.0 µg/ml were toxic to human
spermatozoa. Days 1-4 Quakenbush Special (Qs) mouse embryos were recovered
(n=954) from stimulated females, pooled and randomly apportioned for individual
treatments of different concentrations of ferric chloride (2, 5, 10, 20 and 50 µM for
tolerance study and 100, 200, 300, 400 and 500 µM/L for toxicity study). The
investigation on iron toxicity utilized 206 day 2 Qs mouse embryos. Medium
supplemented with iron (2 to 50 µM/L of ferric chloride) had higher percentage of
blastocysts than control in all treatments. In contrast, the percentages of blastocysts
were lower than control in another experiment performed to investigate iron toxicity
which contained 100 to 500 µM/L.
This study found that ferric iron at physiological levels of human plasma appears to
enhance spermatozoa motility, preserve its DNA integrity and may increase percentage
of blastocysts developed and embryo development because of its critical role in cell
proliferation. However, increasing the concentrations of ferric iron above the
physiological levels had harmful effects on spermatozoa motility, sperm DNA integrity
and blastocysts development. |
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