Improving the biosafety of cell sorting by adaptation of a cell sorting system to a biosafety cabinet.

BACKGROUND: The jet-in-air cell sorters currently available are not very suitable for sorting potentially biohazardous material under optimal conditions because they do not protect operators and samples as recommended in the guidelines for safe biotechnology. To solve this problem we have adapted a cell sorting system to a special biosafety cabinet that satisfies the requirements for class II cabinets. With aid of this unit, sorting can be performed in conformance with the recommendations for biosafety level 2. METHODS: After integrating a modified fluorescence-activated cell sorter (FACS) Vantage into a special biosafety cabinet, we investigated the influence of the laminar air flow (LAF) inside the cabinet on side stream stability and the analytical precision of the cell sorter. In addition to the routine electronic counting of microparticles, we carried out tests on the containment of aerosols, using T4 bacteriophage as indicators, to demonstrate the efficiency of the biosafety cabinet for sorting experiments performed under biosafety level 2 conditions. RESULTS: The experiments showed that LAF, which is necessary to build up sterile conditions in a biosafety cabinet, does not influence the conditions for side stream stability or the analytical precision of the FACS Vantage cell sorting system. In addition, tests performed to assess aerosol containment during operation of the special biosafety cabinet demonstrated that the cabinet-integrated FACS Vantage unit (CIF) satisfies the conditions for class II cabinets. In the context of gene transfer experiments, the CIF facility was used to sort hematopoietic progenitor cells under biosafety level 2 conditions. CONCLUSIONS: The newly designed biosafety cabinet offers a practical modality for improving biosafety for operators and samples during cell sorting procedures. It can thus also be used for sorting experiments with genetically modified organisms in conformance with current biosafety regulations and guidelines.     

Cell sorting of formalin-treated pathogenic Mycobacterium paratuberculosis expressing GFP

GFP is widely used as a molecular tool for the study of microbial pathogens. However, the manipulation of these pathogenic microorganisms poses a health threat to the laboratory worker, requiring biosafety level II or III containment. Although the GFPfluorophore is tolerant toformalin, a thorough analysis of this treatment on fluorescent output in prokaryotic systems has not been described. In addition, the analysis of microorganisms expressing GFP often depends on specialized equipment, which may not be housed in biosafety level II or III laboratories. Therefore, we sought to develop a safe and effective method for manipulating the GFP-expressing pathogenic bacterium Mycobacterium avium subsp, paratuberculosis (M. paratuberculosis) utilizing a formalin treatment that would permit the analysis of GFP fluorescence without requiring stringent biosafety containment. We demonstrate that formalin-treated M. paratuberculosis expresses 50% less fluorescence than viable cells, but this reduction is still compatible with spectrofluorometry and cell sorting. Furthermore, plasmid DNA that expresses GFP can be recovered efficiently from nonviable, sorted fluorescent cells. This approach is flexible, provides an additional margin of safety for laboratory personnel, and can be easily applied to other pathogenic microorganisms expressing GFP.     

Novel rapid method for visualization of extent and location of aerosol contamination during high-speed sorting of potentially biohazardous samples

BACKGROUND: Containment of potentially biohazardous aerosols that result from high-speed sorting of human cells has been an increasingly important problem in analytical cytometry. The current method for assessing the efficiency of aerosol containment involves detection of aerosols containing sorted T4 bacteriophage on lawns of T4-susceptible Escherichia coli on plates that are placed in and around the sort area. Although this method is sensitive, it is time consuming and involves maintenance and handling of bacteria and sorting of bacteriophage that may themselves serve as sources of contamination for sorted viable human cells. METHODS: Glo Germ (5-microm melamine copolymer resin beads), which are fluorescent under black light illumination, were sorted on a Beckman-Coulter Elite ESP sorter in order to visualize deposition of aerosols under normal and mock failure modes. RESULTS: Glo Germ was successfully used under both normal sorting conditions, as well as mock failure mode, to visualize aerosol formation. CONCLUSIONS: We have developed a method to examine aerosol containment using modified Glo Germ, a product used for teaching aseptic technique in hospitals, industry, restaurants, and schools. Use of this technique represents a rapid, inexpensive, qualitative analysis of the extent and location of aerosol contamination from cell sorters.     

Detection of adeno- and lentiviral (HIV1) contaminations on laboratory surfaces as a tool for the surveillance of biosafety standards

Aims: As a biosafety laboratory, we survey the handling of adenovirus type 5 (Ad5) and HIV1‐derived lentivirus in contained‐use facilities in Switzerland to identify insufficiencies of the safety precautions taken by the laboratories. Methods and Results: In the past 9 years, we took 430 swab samples from various types of surfaces in research laboratories. Samples were examined for Ad5 contaminations by real‐time PCR and infectivity assay or for the presence of lentivirus (HIV1) nucleic acids by real‐time (RT) PCR. Samples collected from centrifuges did not only contain Ad5 DNA more frequently but also exhibited higher numbers of Ad5 and lentiviral (HIV1) DNA copies than swabs from any other area of sampling. Five of ten samples containing infectious Ad5 particles or lentivirus (HIV1) RNA were found in samples taken from centrifuges. Ad5 contamination rates were higher in the tube holder and lower on the inner wall of the rotor chamber in centrifuges that were fitted with aerosol tight covers compared to centrifuges without covers. Conclusions: Our results allowed the comparison of hygiene standards of different laboratories and lead to the identification of centrifuges as hotspots for contaminations. Significance and Impact of the Study: Based on our results, we propose to use the collected data as a tool for rating future swab results. Furthermore, the amount of Ad5 and HIV1‐derived lentivirus DNA could serve as an indicator of the level of good laboratory practice in contained‐use laboratories handling these viral vectors.     

Aseptic laboratory techniques: plating methods

Microorganisms are present on all inanimate surfaces creating ubiquitous sources of possible contamination in the laboratory. Experimental success relies on the ability of a scientist to sterilize work surfaces and equipment as well as prevent contact of sterile instruments and solutions with non-sterile surfaces. Here we present the steps for several plating methods routinely used in the laboratory to isolate, propagate, or enumerate microorganisms such as bacteria and phage. All five methods incorporate aseptic technique, or procedures that maintain the sterility of experimental materials. Procedures described include (1) streak-plating bacterial cultures to isolate single colonies, (2) pour-plating and (3) spread-plating to enumerate viable bacterial colonies, (4) soft agar overlays to isolate phage and enumerate plaques, and (5) replica-plating to transfer cells from one plate to another in an identical spatial pattern. These procedures can be performed at the laboratory bench, provided they involve non-pathogenic strains of microorganisms (Biosafety Level 1, BSL-1). If working with BSL-2 organisms, then these manipulations must take place in a biosafety cabinet. Consult the most current edition of the Biosafety in Microbiological and Biomedical Laboratories (BMBL) as well as Material Safety Data Sheets (MSDS) for Infectious Substances to determine the biohazard classification as well as the safety precautions and containment facilities required for the microorganism in question. Bacterial strains and phage stocks can be obtained from research investigators, companies, and collections maintained by particular organizations such as the American Type Culture Collection (ATCC). It is recommended that non-pathogenic strains be used when learning the various plating methods. By following the procedures described in this protocol, students should be able to: Perform plating procedures without contaminating media. Isolate single bacterial colonies by the streak-plating method. Use pour-plating and spread-plating methods to determine the concentration of bacteria. Perform soft agar overlays when working with phage. Transfer bacterial cells from one plate to another using the replica-plating procedure. Given an experimental task, select the appropriate plating method.     

我国生物安全科技工作成就与展望

生物安全是国家安全的重要组成部分,科技是国家生物安全的重要战略支撑。针对我国当前面临的重大生物安全威胁,科技部进行了一系列项目部署,不断加强生物安全科技支撑能力建设。本文重点总结了自"十二五"以来我国生物安全科技工作在重大新发突发传染病防控、外来物种入侵甄别与防控、实验室生物安全、生物安全特种资源库建设、基因合成与编辑技术等方面取得的主要成就,展望了前沿生物技术发展与学科交叉融合所带来的新型生物安全风险与防控机遇,并对我国生物安全科技发展提出建议。     

Characterization of aerosols produced by cell sorters and evaluation of containment

Despite the recognition of potential aerosol hazards associated with cell sorting by the flow cytometry community, there has been no previous study that has thoroughly characterized the aerosols that can be produced by cell sorters. In this study, an aerodynamic particle sizer was used to determine the concentration and aerodynamic diameter (AD) of aerosols produced by a FACS Aria II cell sorter under various conditions. Aerosol containment and evacuation were also evaluated using this novel methodology. The results showed that high concentrations of aerosols in the range of 1-3 μm can be produced in fail mode and that with decreased sheath pressure, aerosol concentration decreased and AD increased. Although the engineering controls of the FACS Aria II for containment were effective, sort chamber evacuation of aerosols following a simulated nozzle obstruction was ineffective. However, simple modifications to the FACS Aria II are described that greatly improved sort chamber aerosol evacuation. The results of this study will facilitate the risk assessment of cell sorting potentially biohazardous samples by providing much needed data regarding aerosol production and containment.     

医学微生物学教学中《生物安全法》的引介

医学微生物学是医学生所学全部课程中与生物安全关系最密切的课程之一,新近颁布施行的《生物安全法》中有多个主题与医学微生物学内容密切相关。阐述了在医学微生物学教学过程中,通过引介《生物安全法》的相关主题引导学生总结新发突发传染病及动物源性传染病的概念、特点及危害,关注传染病的动物起源问题,了解生物恐怖、生物犯罪、微生物法医学的概念、特点及典型案例等,以此来巩固、加深及拓展学生对医学微生物学的理解和掌握,使学生逐渐树立起生物安全意识,从而提高教学效果。     

Risks faced by laboratory workers in the AIDS era.

Laboratory workers are at occupational risk of exposure to microrganisms that cause a wide variety of diseases, from inapparent to life-threatening ones. Principal routes of transmission include percutaneous and permucosal inoculation (comprising clinical inapparent cutaneous or mucosal exposure to blood or blood products), inhalation, and ingestion. The appearance of the Acquired Immunodeficiency Syndrome (AIDS) epidemic and the first reports of occupational Human Immunodeficiency Virus (HIV) infections in health care workers resulted in high anxiety among laboratory workers. Indeed, 21% of worldwide documented cases of occupational HIV infection occurred among laboratory workers. Research laboratories pose the highest risk of infection. Safe methods for managing infectious agents ("containment") in the laboratory setting include laboratory practice and technique, safety equipment, and facility design. Infection control in the laboratory setting should take into account adherence to guidelines (biosafety levels), education and training, and the development of safety products designed to reduce the risk of exposure.     

The emerging international regulatory framework for biotechnology

Debate about the potential risks of genetically modified organisms (GMOs) to the environment or human health spurred attention to biosafety. Biosafety is associated with the safe use of GMOs and, more generally, with the introduction of non-indigenous species into natural or managed ecosystems. Biosafety regulation--the policies and procedures adopted to ensure the environmentally safe application of modern biotechnology--has been extensively discussed at various national and international forums. Much of the discussion has focused on developing guidelines, appropriate legal frameworks and, at the international level, a legally binding international biosafety protocol--the Cartagena Protocol on Biosafety. The Protocol is one among various international instruments and treaties that regulate specific aspects relevant to agricultural biotechnology. The present article presents the main international instruments relevant to biosafety regulation, and their key provisions. While international agreements and standards provide important guidance, they leave significant room for interpretation, and flexibility for countries implementing them. Implementation of biosafety at the national level has proven to be a major challenge, particularly in developing countries, and consequently the actual functioning of the international regulatory framework for biotechnology is still in a state of flux.     

Ultra high-speed sorting.

BACKGROUND: Cell sorting has a history dating back approximately 40 years. The main limitation has been that, although flow cytometry is a science, cell sorting has been an art during most of this time. Recent advances in assisting technologies have helped to decrease the amount of expertise necessary to perform sorting. METHODS: Droplet-based sorting is based on a controlled disturbance of a jet stream dependent on surface tension. Sorting yield and purity are highly dependent on stable jet break-off position. System pressures and orifice diameters dictate the number of droplets per second, which is the sort rate limiting step because modern electronics can more than handle the higher cell signal processing rates. RESULTS: Cell sorting still requires considerable expertise. Complex multicolor sorting also requires new and more sophisticated sort decisions, especially when cell subpopulations are rare and need to be extracted from background. High-speed sorting continues to pose major problems in terms of biosafety due to the aerosols generated. CONCLUSIONS: Cell sorting has become more stable and predictable and requires less expertise to operate. However, the problems of aerosol containment continue to make droplet-based cell sorting problematical. Fluid physics and cell viability restraints pose practical limits for high-speed sorting that have almost been reached. Over the next 5 years there may be advances in fluidic switching sorting in lab-on-a-chip microfluidic systems that could not only solve the aerosol and viability problems but also make ultra high-speed sorting possible and practical through massively parallel and exponential staging microfluidic architectures.     

利用决策树方法建立转基因植物环境生物安全评价诊断平台

转基因技术及其产品是解决世界粮食问题的重要途径之一, 但是包括食品和环境安全在内的转基因生物安全评价是转基因技术及其产品商品化应用的前提和保证。现有的人为生物安全评价方法存在着一定的不足, 难以应对数量日益增加和内容日趋复杂的转基因产品的安全评价需求, 因此找寻一种客观和高效的评价方法势在必行。决策树(decision tree)方法是现今广泛使用的数据挖掘和分析的决策方法之一, 通过将需要解答问题的层层分解并分别解决, 最终得到理想的决策结果, 在处理复杂问题方面具有独特的优势。本文旨在通过介绍决策树的概念、特性、种类及其构建方法, 探索将决策树方法应用于建立转基因植物环境生物安全评价诊断平台的可行性, 并分析构建的诊断平台在高效、准确和客观地进行转基因植物环境生物安全评价, 以及对新一代转基因产品环境安全性的预测和普及环境安全知识等方面的优势, 为进一步推动转基因技术的发展和转基因产品的安全利用奠定基础。     

基于DPSEEA模型构建生物安全评价体系：以深圳市为例

由于生物安全内涵外延和基本要素的模糊性、评价指标及评价方法的多元性等因素的限制, 我国至今尚未形成全面有效的生物安全评价指标体系。为构建生物安全评价体系, 研判生物安全现状, 本文首先运用规范分析法剖析《生物安全法》中有关“生物安全”定义的特点及不足, 从国家安全角度认为生物安全是指国家有效防范和应对危险生物因子及相关因素的威胁, 维护和保障自身安全与利益的能力和状态。明晰了生物安全的外延, 即只有对国家安全利益、民众健康、生态环境保护产生威胁的生物风险, 才是生物安全所规制的对象。其次, 生物安全基本要素包括自然生物安全和社会经济生物安全。自然生物安全主要指民众健康和生态环境保护方面, 包括生物个体安全和生物多样性安全。社会经济生物安全的关注点在国家安全利益, 即社会稳定和国家经济利益, 包括生物技术安全、生物实验室安全。第三, 以生物安全基本要素为管理对象的尺度, 将国家安全利益、民众健康和生态环境保护作为评价主体, 以生物法治为理念, 运用模型构建法, 将定性指标和定量指标相结合, 基于驱动力‒压力‒状态‒接触‒影响‒行动模型(driving force-pressure-state-exposure-effect-action, DPSEEA)构建了一套具有生物法治特色的生物安全评价指标体系, 包括生物安全法律法规体系健全水平、生物安全所涉违法犯罪行为的打击力度、生物安全各部门机构协调机制的建立和完善程度、符合规定标准的生物实验室数量和百分比、生物安全人才数量及密度、对生物产业和基本卫生部门的官方援助及其他途径投资总额、疫苗覆盖的目标人群比例、生物安全的宣传教育普及率8项评价指标在内共32项生物安全评价指标。最后, 基于实地调研及数据统计分析, 以2019年和2020年深圳生物安全工作为例对评价体系进行验证。结果显示, 深圳生物安全工作在农业生物安全、动植物防疫、防范外来物种入侵方面成果显著; 但仍在法律法规体系、生物安全人才培养和资金投入、生物安全普及率方面存在不足。针对上述问题提出完善生物安全法律法规体系并注重法律协调衔接、“一个健康”实现多元协同生物治理、加强人才培养和资金投入、加强生物安全宣传教育等建议。     

三级生物安全实验室感染性废弃物处理相关问题的探讨

在生物安全管理的各环节中,感染性废弃物的处理是控制实验室生物安全的关键环节.为此,我国制定了关于感染性废弃物处理的法律、法规,以避免污染实验室或环境.本三级生物安全实验室运行的3年中,在处理感染性废弃物时遇到了若干需要认真对待的细节,如固体感染性废弃物处理过程中的灭菌环节、消毒剂使用对压力蒸汽灭菌器的损伤、液体感染性废...     

Containment of arthropod disease vectors

Effective containment of arthropod vectors of infectious diseases is necessary to prevent transmission of pathogens by released, infected vectors and to prevent vectors that escape from establishing populations that subsequently contribute to increased disease. Although rare, past releases illustrate what can go wrong and justify the need for guidelines that minimize risks. An overview of recommendations for insectary facilities, practices, and equipment is provided, and features of four recently published and increasingly rigorous arthropod containment levels (ACLs 1-4) are summarized. ACL-1 is appropriate for research that constitutes the lowest risk level, including uninfected arthropods or vectors that are infected with micro-organisms that do not cause disease in humans, domestic animals, or wildlife. ACL-2 is appropriate for indigenous and exotic arthropods that represent a moderate risk, including vectors infected or suspected of being infected with biosafety level (BSL)-2 infectious agents and arthropods that have been genetically modified in ways that do not significantly affect their fecundity, survival, host preference, or vector competence. ACL-3 is recommended for arthropods that are or may be infected with BSL-3 infectious agents. ACL-3 places greater emphasis on pathogen containment and more restricted access to the insectary than ACL-2. ACL-4 is intended for arthropods that are infected with the most dangerous BSL-4 infectious agents, which can cause life-threatening illness by aerosol or arthropod bite. Adherence to these guidelines will result in laboratory-based arthropod vector research that minimizes risks and results in important new contributions to applied and basic science.     

Guidelines for the prevention of simian immunodeficiency virus infection in laboratory workers and animal handlers

The authors are members of a working group that formulated guidelines to minimize transmission of simian immunodeficiency virus (SIV) infection to man. Biosafety level (BSL) 2 standards are recommended for handling of clinical specimens and housing of SIV inoculated animals. Manipulation of SIV preparations may be performed in a BSL 2 facility with additional BSL 3 practices and equipment; for large volume or concentrated preparations of SIV BSL 3 containment is necessary. Written policies regarding management and testing of workers exposed to SIV are recommended.     

Safe biotechnology (5). Recommendations for safe work with animal and human cell cultures concerning potential human pathogens

The benefits of using animal or human cell cultures have been clearly demonstrated in diagnostic and therapeutic research and in their application for manufacturing. Cell cultures serve as a tools for the production of vaccines, receptors, enzymes, monoclonal antibodies and recombinant DNA-derived proteins. They represent an integral part of drug development for which corresponding facilities, equipment and manufacturing processes are required. Although the cells themselves offer no particular risk to workers in laboratories and production areas or to the environment, the cell cultures may be contaminated with viruses, mycoplasma, bacteria, yeast and fungi or might contain endogenous viruses. The containment level for animal and human cells is therefore determined by the risk class of these agents. The history of animal and human cell cultures has proved that they can be handled safely. The recommendations in this publication concern the safe handling of cell cultures (tissue explants, primary cell cultures) and permanent cell lines of animal and human origin. A classification system of safety precautions has been elaborated according to the potential for contamination with the pathogenic agents involved. Correspondence to: DECHEMA, EFB Secretariate, Postfach 150101, W-6000 Frankfurt/Main 15     

Risk of occupationally acquired illnesses from biological threat agents in unvaccinated laboratory workers

Many vaccines for bioterrorism agents are investigational and therefore not available (outside of research protocol use) to all at-risk laboratory workers who have begun working with these agents as a result of increased interest in biodefense research. Illness surveillance data archived from the U.S. offensive biological warfare program (from 1943 to 1969) were reviewed to assess the impact of safety measures on disease prevention (including biosafety cabinets [BSCs]) before and after vaccine availability. Most laboratory-acquired infections from agents with higher infective doses (e.g., anthrax, glanders, and plague) were prevented with personal protective measures and safety training alone. Safety measures (including BSCs) without vaccination failed to sufficiently prevent illness from agents with lower infective doses in this high-risk research setting. Infections continued with tularemia (average 15/year), Venezuelan equine encephalitis (1.9/year), and Q fever (3.4/year) but decreased dramatically once vaccinations became available (average of 1, 0.6, and 0 infections per year, respectively). While laboratory-acquired infections are not expected to occur frequently in the current lower-risk biodefense research setting because of further improvements in biosafety equipment and changes in biosafety policies, the data help to define the inherent risks of working with the specific agents of bioterrorism. The data support the idea that research with these agents should be restricted to laboratories with experience in handling highly hazardous agents and where appropriate safety training and precautions can be implemented.     

What's hot in animal biosafety?

In recent years, the emergence or re-emergence of critical issues in infectious disease and public health has presented new challenges and opportunities for laboratory animal care professionals. The re-emergence of bioterrorism as a threat activity of individuals or small groups has caused a heightened awareness of biosecurity and improved biosafety. The need for animal work involving high-risk or high-consequence pathogens and for arthropod-borne diseases has stimulated renewed interest in animal biosafety matters, particularly for work in containment. Application of these principles to animals retained in outdoor environments has been a consequence of disease eradication programs. The anticipated global eradication of wild poliovirus has prompted the promulgation of new biosafety guidelines for future laboratory and animal work. Increased concern regarding the use of biologically derived toxins and hazardous chemicals has stimulated a new categorization of facility containment based on risk assessment. Recognition that prion disease agents and other high-consequence pathogens require safe handling and thorough destruction during terminal decontamination treatment has led to the development of new biosafety guidelines and technologies. The implementation of these guidelines and technologies will promote state-of-the-art research while minimizing risk to laboratory animals, researchers, and the environment.     

Highly sensitive biosafety model for stem-cell-derived grafts

BACKGROUND: The recent success in the derivation of differentiated cell types from stem cells has raised prospects for the application of regenerative cell therapy. In particular, embryonic stem cells are attractive sources for cell transplantation, due to their immortality and rapid growth. These cells, however, also possess tumorigenic properties, which raises serious safety concerns and makes biosafety testing mandatory. Our goal was to establish a highly sensitive animal model for testing the proliferative potential of stem-cell grafts. METHODS: BALB/c nude mice received cell grafts of non-neoplastic MRC-5 cells containing defined numbers of mouse embryonic stem cells. We either injected 1 million viable cells into the kidney capsule, or mixed 2 million cells with Matrigel for s.c. transplantation. To analyze the possible impact of an intact immune response on tumor development, we also transplanted the cells into immunocompetent mice. Animals were sacrificed when the tumors became >1 cm and were analyzed in detail. RESULTS: The nude mouse model reproducibly allowed detection of 20 tumorigenic cells, and even as few as 2 ES cells were found to form teratoma. Interestingly, the administration of cell grafts at two different application sites resulted in different growth kinetics and tumor phenotypes. The highest level of sensitivity (100% detection of 20 tumorigenic ES cells) was achieved by s.c. injection of cells mixed with Matrigel. The influence of the immune system on tumor-cell development was demonstrated by a higher tumor rate of transplants in immunodeficient nude mice compared with immunocompetent mice. DISCUSSION: We have established a reliable animal model for routine assessment of the biosafety profile of stem-cell-derived cell transplants. This model will facilitate the generation of homogenous non-tumorigenic cell populations, and will help to integrate standardized safety systems into the application of stem-cell-derived grafts for clinical purposes.