Older men with high body-mass index have more sperm cell irregularities


Date:
May 2, 2022
Source:
Cell Press
Summary:
Single-cell analysis of autopsied human testes suggests that
abnormalities associated with aging sperm cells might be exacerbated
by elevated body mass index (BMI).



FULL STORY ========================================================================== Single-cell analysis of autopsied human testes suggests that abnormalities associated with aging sperm cells might be exacerbated by elevated
body mass index (BMI). The research appears May 2nd in the journal Developmental Cell.


==========================================================================
Even though it is well established that older men display reduced
reproductive health, testis aging remains poorly understood at the
molecular and genomic level. Moreover, it has not been clear whether
lifestyle or environmental factors affect this decline.

"Aging may confer a combination of modest molecular changes that sensitize
the testis for additional dysregulation, with pronounced dysregulation
caused when aging is combined with additional factors such as obesity,"
says co-senior author Bradley Cairns of the University of Utah School
of Medicine.

To address this gap, Cairns and co-senior study author Jingtao Guo,
also of the University of Utah School of Medicine, used single-cell
RNA sequencing to profile more than 44,000 cells obtained from autopsy
testis samples from four young men and eight older men. The older donors
were screened for having offspring as young adults to ensure early-adult fertility.

The young samples clustered together and did not display molecular
signatures of aging or a disrupted ability to produce sperm
cells. Surprisingly, the older samples showed only modest age-related
changes in stem cells that give rise to mature sperm, but were clearly classified into two distinct groups. The first group displayed an intact ability to produce sperm cells, with only weak molecular signatures that distinguished them from young samples. By contrast, the second group
showed a very limited ability to develop sperm cells.

Notably, BMI emerged as a critical factor among older individuals. All
donors from the first group had levels lower than 27, whereas all
donors from the second group had levels higher than 30. Taken together,
the results reveal possible molecular mechanisms underlying the complex testicular changes associated with aging, and their possible exacerbation
by concurrent chronic conditions such as obesity.

Moving forward, larger patient cohorts are needed to fully validate the results. Another avenue for future research is to explore whether the testicular cells of older, heavy-set males show unique aging signatures,
or whether they simply display accelerated aging. It is also not
clear whether diet, exercise, diabetes, or altered hormone production
play a role in testis aging. In addition, determining at what age the dysregulation of supporting testis cells emerges, and whether and how
it may be reversible, may lead to improved medical guidance for older men.

"Our study reveals potential biomarkers for diagnosis of testis aging
and directions for potential treatment of aging-related subfertility,"
says Guo.

"It also serves as a foundational dataset for the scientific community
to study how human testis and fertility respond to aging." This work
was supported by the National Institute on Aging.


========================================================================== Story Source: Materials provided by Cell_Press. Note: Content may be
edited for style and length.


========================================================================== Journal Reference:
1. Xichen Nie, Sarah K. Munyoki, Meena Sukhwani, Nina Schmid,
Annika Missel,
Benjamin R. Emery, DonorConnect, Jan-Bernd Stukenborg, Artur
Mayerhofer, Kyle E. Orwig, Kenneth I. Aston, James M. Hotaling,
Bradley R. Cairns, Jingtao Guo. Single-cell analysis of human testis
aging and correlation with elevated body mass index. Developmental
Cell, 2022; DOI: 10.1016/ j.devcel.2022.04.004 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/05/220502120432.htm

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