Infection with the novel coronavirus SARS-CoV-2, which causes the disease COVID-19, may damage testicular tissue without actually infecting the testes.
Scientists from Tongji Medical College, Wuhan, China and Tufts Medical Center, Boston, USA examined 12 men post mortem, aged 49 to 75, who died from COVID-19. Over 80 percent had substantial damage to the seminiferous tubules, that produce and maintain sperm within the testes. In addition, a lower number of Leydig cells was observed, these cells provide hormones that are needed for the production of sperm.
'We speculate that viral membrane proteins, such as the spike protein, may play a role in the injury to seminiferous tubules and Leydig cells,' the researchers wrote in their article published in European Urology Focus. However, they also state that the damage could have been caused by steroid treatment, temperature fluctuations, lack of oxygen or secondary infection during the treatment of COVID-19.
The researchers analysed tissue biopsies and examined them for presence of the virus. In only one of the twelve cases the virus was detected in the testes. In this case the individual also showed a particularly high viral load in other organs, the scientists stated. But, surprisingly they did find damage in several testicular cells that may ultimately harm fertility.
Specifically, the scientists observed a change in the visual appearance of the biopsied tissue. Seminiferous tubules showed loss or sloughing of cell mass. Sertoli cells, that are part of the seminiferous tubes, were particularly affected, appearing stretched and deformed. Additionally, the number of the hormone-producing Leydig cells was reduced.
In contrast, a control group of five individuals who died from causes unrelated to COVID-19, did not show any injuries to tubules within the testes, suggesting these testicular changes are indeed COVID-19 related. Interestingly the production of sperm was not changed in any of the twelve individuals when compared to uninfected men in the same age group.
It is known that SARS-CoV-2 enters cells via ACE2 receptors, which are present on the surface of many cell types, including those of the male sexual reproductive organs. Even though the virus is not usually found in testes this latest study suggests that actual infection may not be the way in which the novel coronavirus damages the testes.
As this study only focused on patients who had died from COVID-19, it yet remains to be investigated whether patients with less severe disease progression suffer from similar deformation of testicular tissue. It is also unknown whether this may be temporary or could result in permanent damage of the tissue.