Mesenchymal Stromal Cells (MSCs) are a subset of nonhematopoietic adult stem cells, readily isolated from various tissues and easily culture-expanded ex vivo. Intensive studies of the immune modulation and tissue regeneration over the past few years have demonstrated the great potential of MSCs for the prevention and treatment of steroid-resistant acute graft-versus-host disease (GvHD), immune-related disorders, and viral diseases. In immunocompromised individuals, the immunomodulatory activities of MSCs have raised safety concerns regarding the greater risk of primary viral infection and viral reactivation, which is a major cause of mortality after allogeneic transplantation. Moreover, high susceptibilities of MSCs to viral infections in vitro could reflect the destructive outcomes that might impair the clinical efficacy of MSCs infusion. However, the interplay between MSCs and virus is like a double-edge sword, and it also provides beneficial effects such as allowing the proliferation and function of antiviral specific effector cells instead of suppressing them, serving as an ideal tool for study of viral pathogenesis, and protecting hosts against viral challenge by using the antimicrobial activity. Here, we therefore review favorable and unfavorable consequences of MSCs and virus interaction with the highlight of safety and efficacy for applying MSCs as cell therapy.

The presence of abnormal hematologic findings such as lymphopenia, thrombocytopenia, and pancytopenia were diagnosed in severe cases of avian influenza A H5N1. Whether direct viral dissemination to bone marrow (BM) cells causes this phenomenon remains elusive. We explore the susceptibility of the two stem cell types; hematopoietic stem cells (HSCs) and mesenchymal stromal cells (MSCs) isolated from human BM cells or cord blood, to infection with avian H5N1 viruses. For the first time, we demonstrated that the H5N1 virus could productively infect and induce cell death in both human stem cell types. In contrast, these activities were not observed upon human influenza virus infection. We also determined whether infection affects the immunomodulatory function of MSCs. We noted a consequent dysregulation of MSC-mediated immune modulation as observed by high cytokine and chemokine production in H5N1 infected MSCs and monocytes cocultures. These findings provide a better understanding of H5N1 pathogenesis in terms of broad tissue tropism and systemic spread.

Background: Coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its variants, poses an ongoing global threat, particularly in low-immunization coverage regions. Thus, rapid, accurate, and easy-to-perform diagnostic methods are in urgent demand to halt the spread of the virus. Objective: We aimed to validate the clinical performance of the FastProof™ 30 min-TTR SARS-CoV-2 reverse transcription loop-mediated isothermal amplification (RT-LAMP) method using leftover ribonucleic acid (RNA) samples extracted from 315 nasopharyngeal swabs. The sensitivity and specificity of RT-LAMP were determined in comparison with RT-PCR. Result: Out of 315 nasopharyngeal swabs, viral RNA was detected in 154 (48.9%) samples by RT-PCR assay. Compared with RT-PCR, overall sensitivity and specificity of RT-LAMP were 81.82% (95% CI: 74.81–87.57) and 100% (95% CI: 97.73–100), respectively. A 100% positivity rate was achieved in samples with cycle threshold (Ct) <31 for RT-PCR targeting the ORF1ab gene. However, samples with Ct >31 accounted for false-negative results by RT-LAMP in 28 samples. Conclusion: RT-LAMP reliably detected viral RNA with high sensitivity and specificity and has potential application for mass screening of patients with acute COVID-19 infection, when viral load is high.