SARS-CoV-2 and its relationship with the genitourinary tract: Implications for male reproductive health in the context of COVID-19 pandemic.

BACKGROUND: The current outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, named coronavirus disease 19 (COVID-19), is not the first well-known spillover of an animal originated virus to infect humans. However, one of the few to make such a fast jump in a powerful evolutionary shortcut. The incredible pattern of aggressiveness worldwide since the beginning of the outbreak is that up to 20% of those infected need hospitalization and 5% evolve to critical conditions, not limited to respiratory-related issues, but rather to systemic involvement. OBJECTIVE: This study aims to summarize the current knowledge about the effects of SARS-CoV-2 infection on the male genitourinary tract. MATERIALS AND METHODS: A narrative review was carried out to identify articles on the SARS-CoV-2 infection on the male genitourinary system. RESULTS: Considerations were made about the molecular characteristics of SARS-CoV-2 and immune response to coronavirus. We discussed the influence of the virus on the urinary system, potential mechanisms of COVID-19- related acute kidney injury (AKI), and the role of cytokine release syndrome on the renal pathophysiology of the disease. In the male reproductive tract, it was discussed the testis' vulnerability to SARS-CoV-2 invasion and the possible adverse effects on its function and the seminal findings of COVID-19. DISCUSSION AND CONCLUSION: During the COVID-19 pandemic, an international coordinated scientific effort must arise to understand the role of the urogenital system in the SARS-CoV-2 infection in the clinical setting.

The potential use of stem cells derived from human amniotic fluid in renal diseases.

Amniotic fluid (AF) contains a variety of cell types derived from fetal tissues that can easily grow in culture. These cells can be obtained during amniocentesis for prenatal screening of fetal genetic diseases, usually performed during the second trimester of pregnancy. Of particular interest, some expanded sub-populations derived from AF cells are capable of extensive self-renewal and maintain prolonged undifferentiated proliferation, which are defining properties of stem cells. These human AF stem cells (hAFSCs) exhibit multilineage potential and can differentiate into the three germ layers. They have high proliferation rates and express mesenchymal and embryonic markers, but do not induce tumor formation. In this study, hAFSCs derived from amniocentesis performed at 16-20 weeks of pregnancy were isolated, grown in culture, and characterized by flow cytometry and by their potential ability to differentiate into osteogenic, adipogenic, and chondrogenic lineages. After 4-7 passages, 5 × 105 hAFSCs were inoculated under the kidney capsule of Wistar rats that were subjected to an experimental model of chronic renal disease, the 5/6 nephrectomy model (Nx). After 30 days, Nx rats treated with hAFSCs displayed significant reductions in blood pressure, proteinuria, macrophages, and α-smooth muscle actin expression compared with Nx animals. These preliminary results suggest that hAFSCs isolated and expanded from AF obtained by routine amniocentesis can promote renoprotection in the Nx model. Considering that the AF cells not used for fetal karyotyping are usually discarded, and that their use does not raise ethical issues, they may represent an alternative source of stem cells for cell therapy and regenerative medicine.

Células-tronco do líquido amniótico / Amniotic fluid stem cells

Desde o primeiro isolamento e cultivo de células-tronco embrionárias humanas, há mais de 10 anos, seu uso na pesquisa e terapia foi inibida por considerações éticas complexas e pelo risco de transformação maligna destas células indiferenciadas após transplante no paciente. As células-tronco adultas são eticamente aceitas e o risco de transformação maligna é muito baixo. Entretanto, seu potencial de diferenciação e sua capacidade proliferativa são limitados. Cerca de 6 anos atrás, a descoberta de célulastronco no líquido amniótico que expressavam Oct-4, um marcador específico de pluripotencialidade, com alta capacidade de proliferação e diferenciação, iniciou um novo campo promissor na área das células-tronco. Estas células têm potencial de se diferenciar em células dos três folhetos germinativos. Não formam tumores in vivo e não levantam os questionamentos éticos associados com as células-tronco embrionárias humanas. Futuras investigações revelarão se as células-tronco do líquido amniótico realmente irão representar um tipo intermediário com vantagens em relação tanto às células-tronco embrionárias quanto às adultas. Este artigo faz uma revisão acerca destes tópicos e das características biológicas das células-tronco do líquido amniótico.

Since the first successful isolation and cultivation of human embryonic stem cells about 10 years ago, their use for research and therapy has been constrained by complex ethical considerations as well as by the risk of development of malignancies of undifferentiated embryonic stem cells after transplantation into the patient. Adult stem cells are ethically acceptable and the risk of tumor development is low. However, their differentiation potential and proliferative capacity are limited. About 6 years ago, the discovery of Oct-4 expressing amniotic fluid stem cells, a specific marker of pluripotency, with a high proliferative capacity, and multilineage differentiation potential, initiated a promising field of research. These cells, indeed, have the potential to differentiate into cells of all three embryonic germ layers. They do not form tumors in vivo and do not raise ethical concerns. Further investigation will reveal whether these cells really are an intermediate cell type with advantages over both embryonic and adult stem cells. This article reviews the biological characteristics of amniotic fluid stem cells.