Aseptic Techniques and Safety in Cell Culture

Both aseptic and sterile techniques are essential for maintaining the health of a cell culture lab. The difference between an aseptic technique and sterile technique is that sterile techniques ensure a space is completely free of any microorganisms that could cause contamination, while aseptic techniques focus on not introducing any contamination to a previously sterilized environment. For example, before its first use, a cell culture hood might be sterilized using sterile techniques; while using aseptic techniques will maintain its sterility once a researcher has used it to perform a cell culture experiment.

Read on to learn more about why aseptic techniques are critical to maintaining a sterile work area in your cell culture lab.

Aseptic technique is a set of procedures designed to create a barrier between microorganisms in the environment and the sterile cell culture, thereby reducing the likelihood of contamination. The primary elements of aseptic laboratory techniques include a sterile work area, good personal hygiene, sterile reagents and media, and sterile handling.

For a list of suggestions and procedures to help you achieve fundamental aseptic laboratory techniques, view our aseptic techniques checklist.

Aseptic technique in a cell culture lab is important to limit the chance of contamination from biological microorganisms, such as bacteria, fungi, and viruses. Nonsterile supplies, media and reagents, airborne particles laden with microorganisms, unclean incubators, and dirty work surfaces are all sources of biological contamination.

Chemical and biological contaminants, as well as other cell lines can be spread through improper handling and maintenance of your working area. There are many risks when using improper aseptic techniques such as sacrificing the integrity and accuracy of the experiment and wasting valuable lab resources and the time and effort of researchers. You may see altered growth patterns, compromised viability, or even loss of cells. Following a proper aseptic technique, while not 100% fail-safe, gives you a much higher chance of maintaining the health of your cell cultures.

The following checklist provides a concise list of suggestions and procedures to guide you to achieve a solid aseptic laboratory technique. For an in-depth review of aseptic technique, refer to Culture of Animal Cells: A Manual of Basic Technique (Freshney, 2000). For a printable version of the Aseptic techniques checklist for cell culture, request the Cell Culture Basics Handbook.
 

A major requirement of a cell culture laboratory is maintaining an aseptic work area that is restricted to cell culture work. Although a separate tissue culture room is preferred, a designated cell culture area within a larger laboratory can still be used for sterile handling, incubation, and storage of cell cultures, reagents, and media. The simplest and most economical way to provide aseptic conditions is to use a laminar flow hood (i.e., biosafety cabinet).

Cell cultures should always be handled with personal protective equipment (PPE). PPE forms an immediate protective barrier between the personnel and the hazardous agent using items such as gloves, laboratory coats and gowns, shoe covers, boots, respirators, face shields, safety glasses, or goggles for protection. Wearing personal protective equipment also helps reduce the probability of contamination from shed skin as well as dirt and dust from your clothes. These items are often used in combination with biosafety cabinets and other devices that contain the agents or materials being handled.

We recommend that you consult your institution’s guidelines for the appropriate use of PPE in your laboratory.

Once dressed in the appropriate PPE, adhering to sterile handling procedures can help protect your cultures, media, and reagents from contamination. Commercial reagents and media undergo strict quality control to help ensure their sterility, but they can become contaminated while handling. Follow the guidelines below for sterile handling to avoid contaminating them. Always sterilize any reagents, media, or solutions prepared in the laboratory using the appropriate sterilization procedure.

Abiding by aseptic techniques in a cell culture lab helps protect the cultures and the people studying them. In addition to the safety risks common to most everyday workplaces, such as electrical and fire hazards, a cell culture laboratory has several specific hazards associated with handling and manipulating human or animal cells and tissues, as well as toxic, corrosive, or mutagenic solvents and reagents. Common hazards are accidental punctures with syringe needles or other contaminated sharps, spills, and splashes onto skin and mucous membranes, ingestion through mouth pipetting, and inhalation exposures to infectious aerosols.

The fundamental objective of any biosafety program is to reduce or eliminate exposure of laboratory workers and the outside environment to potentially harmful biological agents. The most important element of safety in a cell culture laboratory is the strict adherence to standard microbiological practices and techniques.

The following recommendations are simply guidelines for safe lab practices, and they should not be interpreted as a complete code of practice. Consult your institution’s safety committee and follow local rules and regulations pertaining to laboratory safety.