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Abstract

Male infertility management has made significant progress during the past three decades, especially after the introduction of intracytoplasmic sperm injection in 1992. However, many boys and men still suffer from primary testicular failure due to acquired or genetic causes. New and novel treatments are needed to address these issues. Spermatogenesis originates from spermatogonial stem cells (SSCs) that reside in the testis. Many of these men lack SSCs or have lost SSCs over time as a result of specific medical conditions or toxic exposures. Loss of SSCs is critical in prepubertal boys who suffer from cancer and are going through gonadotoxic cancer treatments, as there is no option of sperm cryopresrvation due to sexual immaturity. The development of SSC transplantation in a mouse model to repopulate spermatozoa in depleted testes has opened new avenues of research in other animal models, including non-human primates. Recent advances in cryopreservation and in vitro propagation of human SSCs offer promise for human SSC autotransplantation in the near future. Ongoing research is focusing on safety and technical issues of human SSC autotransplantation. This is the time to counsel parents and boys at risk of infertility on the possibility of cryopreserving and banking a small amount of testis tissue for potential future use in SSC transplantation.

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Long-term proliferation in culture and germline transmission of mouse male germline stem cells.

Mito Kanatsu-Shinohara, Narumi Ogonuki, Kimiko Inoue … (2003)

Spermatogenesis is a complex process that originates in a small population of spermatogonial stem cells. Here we report the in vitro culture of spermatogonial stem cells that proliferate for long periods of time. In the presence of glial cell line-derived neurotrophic factor, epidermal growth factor, basic fibroblast growth factor, and leukemia inhibitory factor, gonocytes isolated from neonatal mouse testis proliferated over a 5-month period (>10(14)-fold) and restored fertility to congenitally infertile recipient mice following transplantation into seminiferous tubules. Long-term spermatogonial stem cell culture will be useful for studying spermatogenesis mechanism and has important implications for developing new technology in transgenesis or medicine.

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Prenatal and postnatal prevalence of Klinefelter syndrome: a national registry study.

Anders Bojesen, Svend Juul, Claus Gravholt (2003)

The objective of this study was to describe the prevalence of Klinefelter syndrome (KS) prenatally and postnatally in Denmark and determine the influence of maternal age. All chromosomal examinations in Denmark are registered in the Danish Cytogenetic Central Registry. Individuals with KS diagnosed prenatally or postnatally were extracted from the registry with information about age at the time of diagnosis and mother's age. In the period 1970-2000, 76,526 prenatal examinations on male fetuses resulted in the diagnosis of 163 fetuses with KS karyotype, corresponding to a prevalence of 213 per 100,000 male fetuses. Standardization according to maternal age resulted in a prevalence of 153 per 100,000 males. Postnatally, 696 males of 2,480,858 live born were diagnosed with KS, corresponding to a prevalence among adult men of approximately 40 per 100,000. Less than 10% of the expected number was diagnosed before puberty. Advanced maternal age had a significant impact on the prevalence. KS is severely underdiagnosed in Denmark. Only approximately one fourth of adult males with KS are diagnosed. There is a marked delay in diagnosis of the syndrome. A delay in treatment with testosterone may lead to decreased muscle and bone mass with subsequent risk of osteoporosis.

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Human bone marrow derived mesenchymal stem cells do not undergo transformation after long-term in vitro culture and do not exhibit telomere maintenance mechanisms.

Maria Bernardo, Nadia Zaffaroni, Francesca Novara … (2007)

Significant improvement in the understanding of mesenchymal stem cell (MSC) biology has opened the way to their clinical use. However, concerns regarding the possibility that MSCs undergo malignant transformation have been raised. We investigated the susceptibility to transformation of human bone marrow (BM)-derived MSCs at different in vitro culture time points. MSCs were isolated from BM of 10 healthy donors and propagated in vitro until reaching either senescence or passage (P) 25. MSCs in the senescence phase were closely monitored for 8 to 12 weeks before interrupting the cultures. The genetic characterization of MSCs was investigated through array-comparative genomic hybridization (array-CGH), conventional karyotyping, and subtelomeric fluorescent in situ hybridization analysis both before and after prolonged culture. MSCs were tested for the expression of telomerase activity, human telomerase reverse transcriptase (hTERT) transcripts, and alternative lengthening of telomere (ALT) mechanism at different passages. A huge variability in terms of proliferative capacity and MSCs life span was noted between donors. In eight of 10 donors, MSCs displayed a progressive decrease in proliferative capacity until reaching senescence. In the remaining two MSC samples, the cultures were interrupted at P25 to pursue data analysis. Array-CGH and cytogenetic analyses showed that MSCs expanded in vitro did not show chromosomal abnormalities. Telomerase activity and hTERT transcripts were not expressed in any of the examined cultures and telomeres shortened during the culture period. ALT was not evidenced in the MSCs tested. BM-derived MSCs can be safely expanded in vitro and are not susceptible to malignant transformation, thus rendering these cells suitable for cell therapy approaches.