Safety Considerations in the Lab
How we prepared for lab work
All Principal Investigators, mentors, and undergraduate researchers were required to complete lab safety training and safety courses developed by the University of Calgary's Environment Health and Safety (EHS) services prior to working in the lab. These mandatory safety training courses included courses on occupational health and safety, laboratory safety, hazard assessment, incident reporting and investigation, spill response, biosafety, bloodborne pathogens, and an updated versions of the WHMIS course. The courses cover biological containment protocols, handling of hazardous materials such as liquid nitrogen, and disposal of waste, as well as standard safety and laboratory practices. All required us to take a test following each course, which certified safe lab work under the EHS Guidelines. All team members, advisors, and mentors received credit for each course and training program listed, and supervisors were present in the lab at all times to oversee undergraduate work.
The University of Calgary has a university-wide Biosafety Committee, whose guidelines for safe biological laboratory practices were adhered to throughout the project. The team’s lab benches and experimental plans were assessed and deemed safe to proceed with by this Biosafety Committee. The University's Environment Health and Safety (EHS) services provided additional training for individuals working with radiation and irradiated cells.
Our project utilized Bacillus subtilis and a commonly used lab-strain of Escherichia coli, TOP10. Both are non-pathogenic and non-infectious, and are classified as Biosafety Level 1 organisms (BSL-1). Therefore, these organisms posed no significant risk to researchers. Since the BSL-1 cells (E. coli and B. subtilis) have GRAS labelling, the main cloning component of out project did not require ethics approval by review boards. Some team members worked with HCT116 and 1BR3 primary cell lines, which are human colon carcinoma and human skin fibroblast cell lines and are classified as Biosafety Level 2 (BSL-2).The cell lines were received from completely anonymous donors. We handled these cell lines at containment level 2 in accordance with the Bloodborne Pathogens Standard and Biosafety Committee guidelines.
Safety Considerations for the Device
Structure of the Patch
The circular design of the packet containing media and B. subtilis spores encourages equal distribution of liquid pressure around the circumference to prevent the patch from breaking open at the seams. The packets are made of a flexible polyethylene material, which is advantageous for distributing external forces against the patch, such as accidental bumping or squishing. This distribution of pressure prevents the material from rupturing due to accumulated forces along seams or corners.
The fact that our patch is non-invasive and only present in the external part of the body promotes safety better than an implant.
Choosing Patch Materials
All materials used in the patch are chemically and biologically compatible, which decreases the risk of an immune response in the user.
The backing layer of the patch is made up of a strong, flexible, and gas-permeable material. This allows users to move with ease and saves them the worry of the patch tearing apart. This layer also prevents bacteria from escaping.
The size controlling membrane is made up of polymers that prevent bacteria from flowing through the patch, but allow our peptide to pass. The bacteria will not come into contact with the skin, which protects the user from the possibility of infection or immune responses.
The adhesive chosen to affix the patch to the skin has high oxygen/gas permeability, causes low pain upon removal from sensitive skin, and promotes diffusivity of the drug. The adhesive has been tested by Dow Corning (the company that supplied us the adhesive), and it was found to cause no significant effects on test animals.
The release liner is peeled from the adhesive layer and disposed of when the patch is applied to the skin.
Considering Human Use
Advantages of a Patch
Using a patch is preferable to many other drug delivery systems. A patch gives the user the freedom to continue a course of medications even with an upset stomach, as the drug will not need to go through the digestive system. It is less invasive than an implant or injection, and delivers the therapeutic agent continuously, meaning the dosage is always above the threshold required for a therapeutic effect, and the user does not need to worry about taking their medication at the same time each day.
Possible Problems with the Patch
Accidental breakage of the patch while attached to skin may cause infections if the area is not disinfected properly. The risk is increased if there are open wounds on the skin near the application area.
Patch may cause severe harm if swallowed.
Potential skin irritation may occur. However, our initial mouse trials have shown no signs of inflammation.
in vivo Mouse Trials
With the mentorship of Dr. Jenne, the team wrote and submitted an extensive ethics application to the Health Sciences Animal Care Committee (HSACC) at the University of Calgary. The application was evaluated on multiple grounds such as feasibility, morality, and precautions of the testing of our transdermal patch on mice models. The project idea, protocols, and the scientific significance of our transdermal patch were also reviewed. HSACC approved our project under the above mentioned parameters, as our protocols and procedures were deemed moral. The testing of our transdermal patch was carried out based on the approved flowcharts below:
Since no member on the team had completed the Institutional Animal User Training Program (IAUTP) on mice handling and registered with the Institutional Research Information Services Soluion (IRISS), the mice handling work was completed by Dr. Jenne and members of his lab who had previous training and certification. Members of our iGEM team were present at all times during the testing of the transdermal patch in mice models but only as observers.
Containment
Contamination is an issue both on earth and in space, as the bacteria in the patch may be able to infect users of the patch or colonize foreign planets should they be released. To prevent the bacteria from escaping from the patch, there are several engineering controls in place, such as the protective physical barriers that prevent bacteria from diffusing out of the patch, including the backing layer and the selective membrane.
Although our initial diffusion assays have shown that bacteria can diffuse through our semipermeable membrane, we have begun testing with other smaller filters including peptide dialysis membranes and 0.2 micron size filters. We have also had success with membranes used to filter-sterilize liquids.
See pages 15 - 16 of the Device Applied Design Manual to tackle contamination issues.
Future Considerations for Patch Design
If we can determine a better membrane that prevents the diffusion of the bacteria, we can use a two layer semi permeable system where the first layer prevents the diffusion of the bacteria and a second layer which further filters BBI for diffusion.
Safe disposal:
See pages 11 and 12 of the Device Applied Design Manual for disposal information.
Safety Considerations of Biobrick Parts
Public safety: Threonine auxotrophy was employed where integrated cassettes containing flanking regions of homology for the B. subtilis thrC gene were used. This knocked out threonine synthase in our chassis, making it unlikely it would survive outside of conditions where theronine is not supplied.
Environmental safety: It’s possible that our B. subtilis transformed with mBBI could outcompete native microbes and potentially disrupt existing ecologies; however, the integrated mBBI genetic construct would not make a significant difference in the bacteria’s survivability outside the lab. Given the nature of our project and safeguards we have implemented, none of our BioBricks confer unsafe risks to individuals nor the environment.
Future Considerations
We would engineer inducible kill switches that could eradicate the bacteria if need be. Additionally, integrating mBBI in various essential genes required for amino acid synthesis could provide more opportunities for auxotrophy, increasing the safety of using B. subtilis in the device.
Safety Forms
About Our Lab
About Our Project
Final Safety Form
