Novel Impactor and Microsphere-Based Assay Used to Measure Containment of Aerosols Generated in a Flow Cytometer Cell Sorter

Effects of Oscillation Amplitude Variations on QCM Response to Microspheres of Different Sizes

Suspended particulate matter (PMx) is one of the most important environmental pollutants. Miniaturized sensors capable of measuring and analyzing PMx are crucial in environmental research fields. The quartz crystal microbalance (QCM) is one of the most well-known sensors that could be used to monitor PMx. In general, in environmental pollution science, PMx is divided into two main categories correlated to particle diameter (e.g., PM < 2.5 µm and PM < 10 µm). QCM-based systems are capable of measuring this range of particles, but there is an important issue that limits the application. In fact, if particles with different diameters are collected on QCM electrodes, the response will be a result of the total mass of particles; there are no simple methods to discriminate the mass of the two categories without the use of a filter or manipulation during sampling. The QCM response depends on particle dimensions, fundamental resonant frequency, the amplitude of oscillation, and system dissipation properties. In this paper, we study the effects of oscillation amplitude variations and fundamental frequency (10, 5, and 2.5 MHz) values on the response, when particle matter with different sizes (2 µm and 10 µm) is deposited on the electrodes. The results showed that the 10 MHz QCM was not capable of detecting the 10 µm particles, and its response was not influenced by oscillation amplitude. On the other hand, the 2.5 MHz QCM detected the diameters of both particles, but only if a low amplitude value was used.

Validation of a cell integrated next-generation impactor to assess in vitro drug transport of physiologically relevant aerosolised particles

The development of novel inhaled formulations in the pre-clinical stage has been impeded by a lack of meaningful information related to drug dissolution and transport at the lung epithelia due to the absence of physiologically relevant in vitro respiratory models. The objective of the present study was to develop an in vitro experimental model, which combined the next generation impactor (NGI) and two respiratory epithelial cell lines, for examining the aerodynamic performance of dry powder inhalers and the fate of aerosolised drugs following lung deposition. The NGI impaction plates of stage 3 (i.e., a cut-off diameter of 2.82-4.46 µm) and stage 7 (i.e., a cut-off diameter of 0.34-0.55 µm) were modified to accommodate 3 cell cultures inserts. Specifically, Calu-3 cells and H441 cells, which are representative of the bronchial and alveolar epithelia in the lung, respectively, were cultivated at the air-liquid interface on Snapwells^TM with polycarbonate membranes. The aerodynamic particle size distribution of the modified NGI was investigated using resveratrol dry powder formulation (as a model drug). The suitability of such an in vitro model was confirmed by examining the in vitro aerodynamic performance of the model drug as compared to the conventional NGI setup (i.e., without the integrated Snapwell inserts), as well as the effect of experimental conditions (e.g., 60 L/min airflows) on the cells in the integrated Snapwell inserts. After deposition of the aerodynamically fractioned resveratrol, the permeation of the drug across the cell layer to the basolateral chamber of the Snapwell inserts was evaluated over 24 h. Results obtained from the drug transport study showed that the cell-integrated NGI provided realistic drug delivery conditions to the cells that can be used to assess the fate of fractionated aerosol particles. This system enables a better understanding of the in vitro drug deposition in the lungs and allows studies on both aerodynamic characterisation and drug transport (drug biological interactions with the cells) to be performed simultaneously.

Establishing a biosafety plan for a flow cytometry shared resource laboratory

A biosafety plan is essential to establish appropriate practices for biosafety in a shared resource laboratory (SRL). A biosafety plan will contain the essential information for the use of biological samples on specific instrumentation, their apparent risks, and the steps that should be taken to mitigate these risks. Establishment of a biosafety plan can be a daunting task as the variety of pathogens that come through the SRL is highly diverse and may change over time; however, having a plan that can adapt to this variety will provide a framework for addressing concerns and educating personnel and users on biosafety practices. Using resources available at your institution and developing a robust relationship with health and safety personnel at your institution is key to generating an effective biosafety plan. Here we provide a basic underlying structure for a biosafety plan to aid SRL personnel in generating or maintaining their biosafety procedures, and provide guidance for establishing a dynamic, living biosafety plan.

Biosafety during a pandemic: shared resource laboratories rise to the challenge

Biosafety has always been an important aspect of daily work in any research institution, particularly for cytometry Shared Resources Laboratories (SRLs). SRLs are common‐use spaces that facilitate the sharing of knowledge, expertise, and ideas. This sharing inescapably involves contact and interaction of all those within this working environment on a daily basis. The current pandemic caused by SARS‐CoV‐2 has prompted the re‐evaluation of many policies governing the operations of SRLs. Here we identify and review the unique challenges SRLs face in maintaining biosafety standards, highlighting the potential risks associated with not only cytometry instrumentation and samples, but also the people working with them. We propose possible solutions to safety issues raised by the COVID‐19 pandemic and provide tools for facilities to adapt to evolving guidelines and future challenges.

Risk awareness during operation of analytical flow cytometers and implications throughout the COVID-19 pandemic

The COVID-19 pandemic has brought biosafety to the forefront of many life sciences. The outbreak has compelled research institutions to re-evaluate biosafety practices and potential at-risk areas within research laboratories and more specifically within Shared Resource Laboratories (SRLs). In flow cytometry facilities, biological safety assessment encompasses known hazards based on the biological sample and associated risk group, as well as potential or unknown hazards, such as aerosol generation and instrument "failure modes." Cell sorting procedures undergo clearly defined biological safety assessments and adhere to well-established biosafety guidelines that help to protect SRL staff and users against aerosol exposure. Conversely, benchtop analyzers are considered low risk due to their low sample pressure and enclosed fluidic systems, although there is little empirical evidence to support this assumption of low risk. To investigate this, we evaluated several regions on analyzers using the Cyclex-d microsphere assay, a recently established method for cell sorter aerosol containment testing. We found that aerosol and/or droplet hazards were detected on all benchtop analyzers predominantly during operation in "failure modes." These results indicate that benchtop analytical cytometers present a more complicated set of risks than are commonly appreciated.

Validation and Application of a Bench Top Cell Sorter in a BSL-3 Containment Setting

Rigorous assessment of the cellular and molecular changes during infection typically requires isolation of specific immune cell subsets for downstream application. While there are numerous options for enrichment/isolation of cells from tissues, fluorescent activated cell sorting (FACS) is accepted as a method that results in superior purification of a wide variety of cell types. Flow cytometry requires extensive fluidics and aerosol droplets can be generated during collection of target cells. Pathogens such as Francisella tularensis, Mycobacterium tuberculosis, Yersinia pestis, and SARS-CoV-2 require manipulation at biosafety level-3 (BSL-3). Due to the concern of potential aerosolization of these pathogens, use of flow cytometric-based cell sorting in these laboratory settings requires placement of the equipment in dedicated biosafety cabinets within the BSL-3. For many researchers, this is often not possible due to expense, space, or expertise available. Here we describe the safety validation and utility of a completely closed cell sorter that results in gentle, rapid, high purity, and safe sorting of cells on the benchtop at BSL-3. We also provide data demonstrating the need for cell sorting versus bead purification and the applicability of this technology for BSL-3 and potentially BSL-4 related infectious disease projects. Adoption of this technology will significantly expand our ability to uncover important features of the most dangerous infectious diseases leading to faster development of novel vaccines and therapeutics.

Procedures for Flow Cytometry-Based Sorting of Unfixed Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infected Cells and Other Infectious Agents

In response to the recent COVID‐19 pandemic, many laboratories are involved in research supporting SARS‐CoV‐2 vaccine development and clinical trials. Flow cytometry laboratories will be responsible for a large part of this effort by sorting unfixed antigen‐specific lymphocytes. Therefore, it is critical and timely that we have an understanding of risk assessment and established procedures of infectious cell sorting. Here we present procedures covering the biosafety aspects of sorting unfixed SARS‐CoV‐2‐infected cells and other infectious agents of similar risk level. These procedures follow the ISAC Biosafety Committee guidelines and were recently approved by the National Institutes of Health Institutional Biosafety Committee for sorting SARS‐CoV‐2‐infected cells. © 2020 International Society for Advancement of Cytometry