The mouse cheek bleed procedure, formally known as submandibular venipuncture, is a widely adopted method for collecting blood samples from mice. This technique is fundamental in scientific research and diagnostics, enabling the gathering of biological information for various studies. Its efficiency and suitability for repeated sampling make it a common practice in biomedical research laboratories.
Why Mouse Cheek Bleed is Used
This method offers distinct advantages for researchers. It allows for repeated blood collection from the same animal over time, which is particularly beneficial for longitudinal studies that track changes like drug efficacy, disease progression, or physiological responses. This capability helps minimize the number of animals needed for a study, aligning with ethical guidelines.
The procedure also enables the collection of a relatively substantial blood volume compared to other non-terminal methods. Researchers can obtain between 50 to 300 microliters of blood. This volume is sufficient for multiple analyses, making it an efficient method for serial blood sampling.
The Procedure: What to Expect
The procedure is performed by trained personnel in a controlled environment to ensure animal welfare and sample quality. Mice are restrained, either manually or with a specialized device, to minimize movement. Some protocols may utilize isoflurane anesthesia, while others perform the procedure on conscious animals with appropriate justification.
A small lancet or a 25-gauge needle is used to puncture the submandibular vein plexus. The puncture site is located slightly behind the mandible and in front of the ear canal. The lancet or needle is inserted to a shallow depth, 1-2 mm, allowing blood to flow immediately.
Blood droplets are then collected into a capillary tube or microcentrifuge tube. Once the desired sample volume is obtained, gentle pressure is applied to the puncture site with a gauze sponge to stop the bleeding. The animal is then returned to its home cage and monitored for recovery.
Ensuring Animal Welfare and Addressing Risks
Despite its benefits, the mouse cheek bleed procedure carries potential risks if not executed with precision and care. Common complications include localized hematoma (bruising), swelling, and minor tissue damage at the puncture site. Infection risk is mitigated through strict adherence to sterile techniques.
Risks are managed through several measures. Personnel undergo extensive training and competency assessments to ensure proficiency. Standard operating procedures (SOPs) are followed, outlining precise steps for restraint, puncture, and post-collection care. Regulatory bodies, such as the Institutional Animal Care and Use Committee (IACUC), provide ethical oversight and mandate analgesia or anesthesia protocols to minimize discomfort. Post-procedure monitoring is conducted to observe animals for any signs of distress or complications.
Other Blood Collection Methods
Researchers have several alternative methods for collecting blood from mice, each suited for different study needs. Tail vein sampling involves puncturing a vein in the mouse’s tail, used for smaller, repeated samples and sometimes requiring warming the tail to dilate vessels. Saphenous vein sampling, a superficial vein method in the hind leg, can provide moderate volumes and may or may not require anesthesia depending on the protocol.
For studies requiring larger blood volumes, particularly at the conclusion of an experiment, cardiac puncture is a terminal procedure where blood is collected directly from the heart. The choice of method depends on factors such as required blood volume, sampling frequency, animal welfare, and whether the procedure is terminal or non-terminal. Each method has unique advantages and disadvantages concerning animal impact and sample quality.