De Biologie van de

Mannelijke Fertiliteit

Sjoerd Repping, PhD

Professor of Human Reproductive Biology

Academic Medical Center, University of Amsterdam,

Amsterdam, the Netherlands (S.Repping@amc.nl)

Testis - anatomy

Testis - blood vessels

Testis – Sertoli cells

Spermatogenesis

Spermatogenesis

Spermatogenesis

Apale Adark

B

Pre-Leptotene

Leptotene

Zygotene

Pachytene

Diplotene

50%50%

1st meiotic division

Spermatogenesis

spermatogonia

Spermiogenesis

Spermatogenesis

Working, et al. (1988)

Spermatogenesis

IIIIV

V

Spermatogenesis

Male infertility

• Impaired semen quality

– Below WHO guidelines

– Correlation between semen quality and chance of pregnancy

WHO guidelines, (1999, 2010), Van der Steeg, et al., F&S (2010)

Causes of male infertility

• Causative factors

– Hyperprolactinemia

– Hypogonadotrophic hypogonadism

– Bilateral cryptorchidism

– Orchitis

– Previous chemo- or radiotherapy

– Genetic causes

• Numerical and structural chromosome abnormalities

• Y-chromosome deletions

• More than 80% of unknown cause

Silber & Repping, HRU (2002), Visser & Repping, Reproduction (2010)

Male infertility

Spermatogenic failure(= impaired sperm production)

Variability in sperm count

WHO Laboratory Manual for the Examination of Human Semen

and Sperm-Cervical Mucus Interaction (1999)

Patients and controls

• Patients– Men with reduced semen quality according to WHO criteria

– Known causes of spermatogenic failure excluded

• Controls– Proven fertile fathers

• Non-paternity excluded?

• (severely) oligozoospermic men can father children

– Vasectomy reversals

• Pre-operative sperm count unknown

– Population controls

• Sperm count unknown

– Men with proven normal spermatogenesis

• Cohort based approach– Methodologically more powerful

• No a priori distinction between healthy and ill

• Comparison of genetically affected vs unaffected

Sperm production variation

Consecutively included cohort male partners of subfertile couples

(n=1,041)

Median concentration: 52 x106/ml

Median total count: 149 x106

Our view on spermatogenesis

Spermatogenesis is a quantitative trait

Obstructive azoospermiaNon-obstructive azoospermia

(sperm with TESE)

Non-obstructive azoospermia

(no sperm with TESE)

Many (genetic) factors control

the rate of sperm production

Testis Epididymis / Vas / Duct Ejaculate

Established genetic causes

• Karyotype abnormalities

– Klinefelter syndrome (47, XXY)

– Translocations

• Y-chromosome aberrations

– Deletions

– Isodicentric Y-chromosomes

• Monogenic disorders

– Kallmann syndrome

– Cystic Fibrosis mutations (CBAVD)

Y-chromosome deletions

Noordam & Repping, COGD (2006)

sperm count (x106 / ml)

n

“normal”

population

gr/grAZFc

5x106 / ml

Y-chromosome deletions

AZFa

P5/P1

Treatment of male infertility

• General treatment

– Intra cytoplasmic Sperm Injection

• Treatment of the non-affected female partner

• Invasive / burdensome

• Rare cases

– Dopamine-agonist (hyperprolactinemia)

– Gonadotropins (hypogonadotropic hypogonadism)

• Future treatment

– Spermatogonial stem cell autotransplantation

• Especially in childhood cancer survivors

SSC autotransplantation

Nude mouse

40 mg/kg Busulphan treatment

4-6 weeks before transplantation

Xenotransplantation

Colonization?

Xenotransplantation

Sadri Ardekani et al., JAMA (2009)

Adult SSCs

Xenotransplantation

Prepuberal

SSCs

Sadri Ardekani et al., submitted (2010)

Summary

• Spermatogenesis is a complex process

• Few causes of spermatogenic failure identified

– Previous chemo- or radiotherapy

– Genetic causes

• Treatment

– Only in rare cases

– ICSI is not a treatment

– Possible future for Spermatogonial Stem Cells

• In vitro propagation of SSCs