Microinjecting cells using a constant-flow microinjection system

New Insights into the Therapeutic Applications of CRISPR/Cas9 Genome Editing in Breast Cancer

Breast cancer is one of the most prevalent forms of cancer globally and is among the leading causes of death in women. Its heterogenic nature is a result of the involvement of numerous aberrant genes that contribute to the multi-step pathway of tumorigenesis. Despite the fact that several disease-causing mutations have been identified, therapy is often aimed at alleviating symptoms rather than rectifying the mutation in the DNA sequence. The Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 is a groundbreaking tool that is being utilized for the identification and validation of genomic targets bearing tumorigenic potential. CRISPR/Cas9 supersedes its gene-editing predecessors through its unparalleled simplicity, efficiency and affordability. In this review, we provide an overview of the CRISPR/Cas9 mechanism and discuss genes that were edited using this system for the treatment of breast cancer. In addition, we shed light on the delivery methods—both viral and non-viral—that may be used to deliver the system and the barriers associated with each. Overall, the present review provides new insights into the potential therapeutic applications of CRISPR/Cas9 for the advancement of breast cancer treatment.

Preparing injection pipettes on a PUL-1 micropipette puller

The efficient delivery of exogenous DNA to cells for expression and function studies is an essential technique of modern cell biology, and direct delivery of genetic material by microinjection remains a reliable means of transfection. Needles for microinjection can either be pulled from glass capillaries on a pipette puller or be purchased premade. When pulling needles, variables such as filament design, heat, pull strength (tension), and delay time between heating and pulling must be addressed. The heat setting affects the length and the tip size of the needle; high heat will typically produce longer needles and finer tips. The pull strength will also affect length and tip size, with greater pull strength producing longer tapered needles with finer tips. Finally, shorter delay times between heating and pulling can result in longer tapers and finer needles; if the delay is too short, the glass forms fibers resembling glass wool rather than usable needles. The advantage of pulling needles in the laboratory is that a variety of different needle types can be pulled, depending on the samples and the cells being injected. The PUL-1 micropipette puller is a robust and inexpensive machine that can be found in many laboratories around the world. New machines are no longer being manufactured, although used ones can still be purchased.

DNA sample preparation and loading sample into pipettes for microinjection of cells

The efficient delivery of exogenous DNA to cells for expression and function studies is an essential technique of modern cell biology, and direct delivery of genetic material by microinjection remains a reliable means of transfection. This protocol describes in general the preparation and loading of plasmid DNA for microinjections. Plasmid DNA can be purified by traditional means such as cesium chloride density ultracentrifugation, or by commercially available resin-based purification kits. The resulting preparation can then be delivered into microinjection needles either by backfilling or by a forward-filling approach.

Plating cells for microinjection

The efficient delivery of exogenous DNA to cells for expression and function studies is an essential technique of modern cell biology, and direct delivery of genetic material by microinjection remains a reliable means of transfection. This protocol describes the general procedures needed to culture cells for microinjection. Coverslips need to be marked so that microinjected cells can be identified at desired time points after injection. Coverslips can be etched by the user, as described here, or pre-etched coverslips can be purchased. Once the coverslips have been etched and sterilized, cells can be plated onto them and allowed to grow.