Old Age and Obesity Lead to Irregularities.

• Position: REPRODUCTIVE HEALTH

Even though it is well established that older men display reduced reproductive health, testis aging remains poorly understood at molecular and genomic levels. 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 dys-regulation, with pronounced dysregulation caused when aging is combined with additional factors such as obesity," says Bradley Cairns of the School of Medicine and Cancer Institute at the University of Utah.

To address this gap, Caims and Jingtao Guo, also of the 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 clearly were classified into two distinct groups. The...