Introduction
In late 2019, an outbreak of pneumonia caused by a newly discovered
coronavirus called Severe acute respiratory syndrome coronavirus 2
(SARS-CoV-2) originated in Wuhan, China . This virus spread quickly
worldwide and let to a severe acute respiratory syndrome known as
”COVID-19” as designated by the World Health Organization (WHO). The
rapid transmission of this novel virus resulted in the WHO declaring it
a pandemic, causing significant changes in social behavior. COVID-19 has
had a profound impact on the health of affected individuals and has also
greatly affected healthcare delivery for all patients, not just those
with COVID-19.
Coronaviruses have a spherical shape awith spike proteins on their
envelope, giving them a club-like appearance. The virus contains a
single-stranded RNA genome with a positive sense, which is enclosed
within a helical nucleocapsid. The entry of SARS-CoV-2 into cells is
mediated by the viral glycoprotein Spike binding to the enzymatic domain
of angiotensin-converting enzyme 2 (ACE-2) on the cell surface . The
virus is then internalized through endocytosis by another membrane bound
protease called transmembrane serine protease 2 (TMPRSS2) . Several
testicular cells, including Sertoli, Leydig cells and spermatogonia
cells, express the ACE-2 receptor on their surface along with proteins
belonging to the angiotensin pathway (ATR1, ATR2, ACE1, and TMPRSS2) .
There receptors and proteins are crucial for SARS-CoV-2 infection. Given
that other RNA viruses such as Ebola, Marburg, and Zika, have been found
to breach the blood-testis barrier and cause inflammation , it was
hypothesized that the male reproductive system could also be a target
for SARS-CoV-2. Additionally, numerous studies have reported that viral
infections significantly contribute to long-term male infertility.
Viruses like HPV (papillomavirus), HSV (herpes simplex virus), and HIV
(immunodeficiency virus) can infect the male reproductive system,
leading to severe consequences for reproductive health , possibly due to
triggering an inflammatory response that result in the release of
inflammatory cytokines and subsequent oxidative stress.
In light of these considerations, we conducted an investigation into the
inflammatory status of the testis by evaluating the presence of
inflammatory cytokines and immune cell populations in seminal fluid
after viral clearance.
To date, there has been limited research on the mechanisms responsible
for the observed effects of COVID-19 infection on semen quality.
However, a recent study has provided valuable insights, confirming that
COVID-19 infection can reduce semen volume, progressive motility,
morphology, sperm count, and DNA integrity .
Preserving male reproductive cells, including semen, epididymal, and
testicular spermatozoa, through cryopreservation, is a crucial approach
for managing permanent or temporary infertility in young men and
children. Cryopreservation technology, in particular, plays an important
role in preserving fertility for these patients . It remains uncertain
whether viral particles persist after cryopreservation, and this
question is especially relevant for cryopreserved samples processed
during the COVID outbreak. Therefore, we investigated the presence of
SARS-CoV-2 genome in seminal fluid before and after cryopreservation
using two methods: conventional slow freezing and vitrification. While
slow freezing is a commonly employed technique in assisted reproductive
technology, seminal fluid vitrification may offer a more efficient and
faster approach for sperm vitrification. However, due to the risk of
contamination from direct contact with liquid nitrogen, sperm
vitrification is considered a hazardous procedure
.13,271113–19
Our aim was to investigate the effect of COVID-19 on the male
reproductive tract. We collected semen samples from 20 patients, with a
median interval of 3 months from SARS-CoV-2 infection. Our findings
demonstrated that both ACE2 and TMPRSS2 were detectable in both the
plasma and sperm fractions even months after the viral infection.
Additionally, we found viral RNA-dependent RNA polymerase (RdRp) in 5
out of 20 patients, indicating the potentional presence of the virus in
the body three months after the initial infection. The study also
revealed high levels of inflammatory cytokines and chemokines in the
plasma seminal fraction of individuals exposed to SARS-CoV-2-,
suggesting the persistence of an inflammatory condition that could
impact spermatozoa vitality. We also identified immune populations in
the semen fraction that are known to play a role in clearing viral
infection, and these populations positively correlate with the
expression of of SARS-CoV-2 receptors and inflammatory cytokines.
Furthermore, we investigated the potential implicaitons of SARS-CoV-2 in
reproductive medicine, particularly in medically assisted reproduction
and gamete cryopreservation. We examined the presence of SARS-CoV-2
genome in seminal fluid before and after cryopreservation using two
methods: conventional slow freezing and vitrification. Our findings
demonstrate that both conventional freezing and vitrification are safe
procedures for preserving male fertility in assisted reproductive
technology programs.