ABSTRACT
Severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) has had a tremendous impact on humanity. Prevention of transmission by disinfection of surfaces and aerosols through a chemical-free method is highly desirable. Ultraviolet C (UVC) light is uniquely positioned to achieve inactivation of pathogens. We report the inactivation of SARS-CoV-2 virus by UVC radiation and explore its mechanisms. A dose of 50 mJ/cm2 using a UVC laser at 266 nm achieved an inactivation efficiency of 99.89%, while infectious virions were undetectable at 75 mJ/cm2 indicating >99.99% inactivation. Infection by SARS-CoV-2 involves viral entry mediated by the spike glycoprotein (S), and viral reproduction, reliant on translation of its genome. We demonstrate that UVC radiation damages ribonucleic acid (RNA) and provide in-depth characterization of UVC-induced damage of the S protein. We find that UVC severely impacts SARS-CoV- 2 spike protein's ability to bind human angiotensin-converting enzyme 2 (hACE2) and this correlates with loss of native protein conformation and aromatic amino acid integrity. This report has important implications for the design and development of rapid and effective disinfection systems against the SARS-CoV-2 virus and other pathogens.
ABSTRACT
The realization of cell replacement therapy derived from human pluripotent stem cells requires full knowledge of the starting cell types as well as their differentiated progeny. Alongside embryonic stem cells, embryonic germ cells (EGCs) are an alternative source of pluripotent stem cell. Since 1998, four groups have described the derivation of human EGCs. This review analyzes the progress on derivation, culture, and differentiation, drawing comparison with other pluripotent stem cell populations.
Subject(s)
Embryo, Mammalian/cytology , Germ Cells/physiology , Pluripotent Stem Cells/physiology , Animals , Cell Culture Techniques/methods , Cell Differentiation , Cell Movement , Cell Proliferation , Cell- and Tissue-Based Therapy/methods , Culture Media/chemistry , Embryo, Mammalian/physiology , Gene Expression Profiling , Gene Expression Regulation, Developmental , Germ Cells/chemistry , Growth Substances/physiology , Humans , MiceABSTRACT
Stem cell therapy offers exciting potential for ambitious cellular replacement to treat human (h) disease, such as Parkinson's disease, Alzheimer's disease or even replacement of the cell death that follows thromboembolic stroke. The realisation of these treatments requires cellular resources possessing three essential characteristics: (i) self-renewal, (ii) the ability to differentiate to physiologically normal cell types and (iii) lack of tumourigenicity. Here, we describe work on human embryonic germ cells (hEGCs), a population of cells alongside human embryonic stem cells (hESCs) with the potential to address these issues.
Subject(s)
Brain Diseases/therapy , Germ Cells/cytology , Neurons/cytology , Pluripotent Stem Cells/cytology , Stem Cell Transplantation/methods , Animals , Gonads/cytology , Gonads/embryology , HumansABSTRACT
Based on evidence suggesting similarities to human embryonic stem cells, human embryonic germ (hEG) cells have been advocated as an alternative pluripotent stem cell resource but have so far received limited attention. To redress this imbalance, human fetal gonads were collected for the isolation and culture of primordial germ cells at 7-9 weeks postconception. We provide evidence for the derivation, culture, and differentiation of hEG cells in vitro. This evidence includes the expression of markers characteristic of pluripotent cells, the retention of normal XX or XY karyotypes, and the demonstration of pluripotency, as suggested by the expression of markers indicative of differentiation along the three germ lineages (ectoderm, mesoderm, and endoderm) and an associated loss of pluripotent markers. In assessing this differentiation, however, we also demonstrate a hitherto unacknowledged overlap in gene expression profiles between undifferentiated and differentiated cell types, highlighting the difficulty in ascribing cell lineage by gene expression analyses. Furthermore, we draw attention to the problems inherent in the management of these cells in prolonged culture, chiefly the difficulty in preventing spontaneous differentiation, which hinders the isolation of pure, undifferentiated clonal lines. While these data advocate the pursuit of pluripotent hEG cell studies with relevance to early human embryonic development, culture limitations carry implications for their potential applicability to ambitious cell replacement therapies.
