Clinical Application of Sperm Chromatin Structure Assessment in Andrology Patients

163 Pages·2011·1.64 MB·English

by  Marij Smit

Clinical Application of Sperm Chromatin
Structure Assessment in Andrology Patients
Marij Smit
ISBN: 978-94-6169-024-1
Cover: “The Milky Way” by Marlene Coombs, photographed by Maarten Dinkelman
Layout and printing: Optima Grafische Communicatie, Rotterdam, the Netherlands
Clinical Application of Sperm Chromatin Structure
Assessment in Andrology Patients
Klinische toepasbaarheid van zaadcel chromatine structuur analyse
in andrologie patiënten
Proefschift
ter verkrijging van de graad van doctor aan de
Erasmus Universiteit Rotterdam
op gezag van de rector magnificus
Prof.dr. H.G. Schmidt
en volgens besluit van het College voor Promoties.
De openbare verdediging zal plaatsvinden op
woensdag 30 maart 2011 om 9.30 uur
door
Marij Smit
geboren te Rotterdam
ProMotiecoMMiSSie
Promotor: Prof.dr. C.H. Bangma
Overige leden: Prof.dr. L.H.J. Looijenga
Prof.dr. J.S.E. Laven
Prof.dr. S.L.S. Drop
Co-promotoren: Dr. G.R. Dohle
Dr. J.C. Romijn
contentS
Chapter 1 General introduction 7
Chapter 2 Clinical correlates of the biological variation of sperm DNA 27
fragmentation in infertile men attending an Andrology
outpatient clinic.
Chapter 3 Sperm chromatin structure is associated with the quality of 43
spermatogenesis in infertile patients.
Chapter 4 Low folate in seminal plasma is associated with increased 57
sperm DNA damage.
Chapter 5 Decreased sperm DNA fragmentation following surgical 73
varicocelectomy is associated with increased pregnancy rates
Chapter 6 Increased level of sperm DNA fragmentation in vasectomy 85
reversal patients has no prognostic value for pregnancy rate.
Chapter 7 Sperm DNA fragmentation in severe male infertility is not 95
associated with IVF/ICSI outcome.
Chapter 8 Sperm DNA integrity in cancer patients before and after 111
treatment.
Chapter 9 General discussion and Summary 125
Chapter 10 Samenvatting 143
Chapter 11 Dankwoord 149
Chapter 12 List of publications 157
PhD portfolio 161

Chapter 1
General introduction

General introduction 9
introduction
1
r
e
t
Infertility, defined as the inability to conceive spontaneously within one year, is a com- p
a
h
mon medical problem. Traditionally, fertility investigations initially focus on the evalu- C
ation of ovulation and tubal patency in females, and on assessment of sperm quantity
and quality in males. In about one third of couples with infertility abnormalities in classic
semen parameters are found, like sperm concentration, motility and morphology. In an-
other one third of patients a combination of infertility-related female and male factors
are seen (WHO 1999). Although sperm quality parameters derived from classic semen
analysis are frequently used to categorise male infertile patients, the prognostic and
diagnostic information they provide is limited with a predictive power that is highest at
the lower ranges of the spectrum (Barratt et al. 2010).
Despite many attempts of the World Health Organization (WHO) and the European
Society for Human Reproduction and Embryology (ESHRE) to standardize semen analy-
sis procedures, e.g. by providing laboratory guidelines (WHO 1999), training courses for
lab technicians and external quality control programmes, semen analysis remains to be
subject to great inter- and intra-observer variation. Moreover, large biological variation
within individuals is observed over time (Alvarez et al. 2003; WHO 2010). Several factors
may contribute to this heterogeneity, such as abstinence time, lifestyle factors (smoking
or obesity), fever, or exposure to medication or gonadotoxins (Evenson et al. 2002), and
probably many others.
When abnormal classic semen parameters are found, further diagnostic procedures
should be undertaken. Low sperm quantity and quality might reflect testicular malfunc-
tion resulting in inadequate spermatogenesis. A multitude of different aetiologies might
be involved, including a history of cryptorchidism or testicular torsion, genital infections,
chronic diseases, varicoceles and genetic abnormalities. Basic andrological investigation
of the infertile male is described in the WHO manual for the standardized investigation,
diagnosis and management of the infertile male. This includes medical history, physical
examination, evaluation of reproductive hormones, and scrotal ultrasound in addition to
classic semen analysis (WHO 2000). Despite this standardized approach, male infertility
remains unexplained in 30-40% of patients with abnormal semen parameters (Nieschlag
et al. 2000). The molecular and or genetic basis of defective sperm function as seen in
for instance varicocele, male accessory gland infection or cryptorchidism are still largely
unknown.
Andrological diagnoses that contribute to infertility like cryptorchidism, testicular
insufficiency and idiopathic sperm abnormalities can often not be surgically or medically
modified to increase a couples chances of natural conception. Treatment focuses on the
achievement of pregnancy using assisted reproduction techniques (ART). Traditional se-
men parameters are used to select the most suitable type of available ART i.e. intra uter-
10 Chapter 1
ine insemination (IUI), in vitro fertilization (IVF) or intra cytoplasmatic sperm injection
(ICSI). In azoospermic men spermatozoa can be surgically retrieved from the epididymis
(percutaneous epididymal sperm aspiration PESA) and testis (testicular sperm extraction
TESE) and subsequently used in an ICSI procedure. Males with impaired sperm function
are able to father children using widely available IVF/ICSI. It is estimated that ARTs have
accounted for over 3 million babies since the first IVF baby was born in 1978 (Carrell et
al. 2010). Reports examining long term health consequences of IVF babies are limited,
however, recent studies have described increased intrauterine growth restriction, lower
birth weights and perinatal mortality in IVF/ICSI offspring (Steel et al. 2009). In addition,
ICSI babies have a higher risk of de novo sex chromosome abnormalities and loss of im-
printing genes associated with otherwise rare conditions such as Beckwith-Wiedemann
and Angelman syndrome (Feng et al. 2008; Kurinczuk 2003).
It is noteworthy that normozoospermic males with partners with normal fertility pa-
rameters may be unable to conceive even when ART is used to establish a pregnancy. In
these couples, available sperm function and oocyte quality assessment fails to identify
deficits that may cause difficulties in gamete fusion and embryo development.
In the less frequent case of surgical treatment of male infertility, the evaluation of
the effect of surgical treatment of male fertility disorders that aim to enhance sperm
parameters is seriously hampered by the characteristic variation of quality in semen
analysis parameters over time. In this view, the treatment of the most common abnor-
mality seen in infertile males, the varicocele, is still controversial. Critics oppose that
the increase in sperm concentration and motility following surgical treatment could
also have occurred without treatment as the consequence of natural variation of semen
parameters over time. This phenomenon is referred to as regression to the mean (Evers
et al. 2003).
The above mentioned considerations implicate the need for more robust biomarkers
for sperm function. There is need for novel functional, genomic and molecular sperm
quality markers to improve treatment outcome and the selection of spermatozoa with
an intact genome to guarantee safe reproduction in ART.
As long as such sperm quality markers have not been developed, traditional basic
seminology will continue to be used as the sole diagnostic tool in male infertility investi-
gations, despite its severe limitations and limited diagnostic and prognostic discrimina-
tive power. Novel markers should therefore preferably be linked to a different biological
principle.
DNA integrity would possibly be a suitable candidate. Since the 1980’s, abnormali-
ties in the structural organization of sperm DNA and its negative influences on the male
fertilizing potential are being investigated in both animal and human fertility clinics.
Such abnormalities are considered to be a complementary, potentially independent,
diagnostic tool in the management of male infertility. Initial clinical data demonstrated