ABSTRACT
Hematopoietic stem cells (HSCs) are critical for maintaining healthy blood and immune cell populations. They’re also valuable resources and targets for medical treatments, such as HSC transplantation and gene therapy. However, these blood cell precursors are susceptible to viral infection, which can cause blood disorders and limit the efficacy of HSC-based therapies. In fact, viral infection is a leading cause of complications and death among HSC transplant recipients. For example, latent cytomegalovirus can become reactivated after transplantation leading to immunosuppression, pneumonia, encephalitis, and graft failure. HSC transplantation also reduces the numbers of T cells that are specifically cytotoxic toward the mononucleosis- inducing Epstein–Barr virus. Furthermore, recipients of HSC transplants are more susceptible to infection by SARS-CoV-2, the cause of the COVID-19 pandemic. SARS-CoV-2, in turn, can induce numerous blood abnormalities, such as thrombocytopenia, lymphocytopenia, anemia, hypercoagulability, and systemic thrombosis in part because HSCs express SARS-CoV-2 receptors. More research is needed to determine the best ways to prevent viral infection of these essential cells in both endogenous and transplantation contexts, in order to reduce serious blood disorders and related mortality in the clinic.