Modified Blood Collection from Tail Veins of Non-anesthetized Mice with a Vacuum Blood Collection System and Eyeglass Magnifier

This study reports blood sampling from tail vein in mice using a vacuum extraction tube system with eyeglasses magnifier. Our method is easy to practice and could be used for repeat blood sampling in mice. A mouse is placed into the plastic restraining holder at first.

The tail is cleaned and wiped with 70%ethanol. Then the operator wears the eyeglass magnifier to improve the viewing of the mouse tail. A butterfly needle tip is then inserted into one of the dilated lateral tail veins, and the blood is collected into the vacuum collection tube through the rubber end of the butterfly needle.

Finally the needle is removed and the blood collection process is finished. Tail vein is a preferred location for blood sampling. This blood sampling method is related to minimal injury to mice, however tail vein of the mice is very thin so that is sometimes difficult to puncture, here we describe a simple tail vein blood sampling method in on lab test mice using a vacuum extraction tube system.

This method is simple and efficient and it can be used to obtain required blood repeatedly in mice. The procedure will be demonstrated by two members of our laboratory, Xiaoyan Liu and Wusong Zou To start, we place a plastic restraining holder, vacuum tubes with rubber stopper, and a double pointed needle, and eyeglasses magnifier on a sterile surface. Next, place a mouse into the plastic restraining holder.

Front and hind paws of the mouse should be in a comfortable position. To obtain blood sample, wash the tail with warm water 20 to 30 Celsius degrees, wipe the tail with 70%ethanol saturated cotton balls to expand the vein. Select the right or left tail vein for blood sampling.

Grasp lower portion of the tail gently and keep the tail straight during blood sample collection. Wear the eyeglasses magnifier to improve the viewing to facilitate puncture of the tail vein. Insert the 22 gauge butterfly needle tip into one of the lateral tail veins around one half distal from the tip of the tail at angle of approximately 10 degrees, moving towards the base of the tail for multiple samples.

Collect blood into the vacuum collection tube by inserting the rubber end of the butterfly needle into the vacuum blood collection tube. The tail of mice can be used for several blood collections, as often as needed, according to the approved protocol. It is not always easy to obtain enough blood volume from the thin and low blood flow tail vein of mice with the traditional method.

Our method is simple and efficient and can be used to obtain adequate blood volume repeatedly in mice. It is reported that up to 10%of the total blood volume can be safely removed from a healthy animal at two week intervals, so about 175 microliters blood sample of mice was collected each time in accordance with ethics principals. Two, it is vital to extend the tail to avoid its movement in the process of blood sampling.

In order to avoid blood coagulation in the needle, another puncture position should be selected if blood stops flowing out over 15 seconds. Successful blood collection was defined as obtaining 175 microliters blood each time. Maximal puncture times were set to three trials.

If the total blood volume was lower that 175 microliters after the third puncture, it was defined as a failed blood collection. When adequate sample volume has been collected, withdraw the needle from the vein and briefly apply pressure to the insertion site to stop the bleeding. To collect plasma, use tubes that contain EDTA, an anticoagulant, gently invert the tube several times to mix anticoagulant with the blood and place the samples on ice vertically.

Spin whole blood sample collection tubes in the refrigerated centrifuge for 10 minutes. Extract the plasma, taking care not to disturb the red and white blood cell layers. To collect serine, use tubes without anticoagulant.

Both types of samples can be used immediately or stored at under 80 degrees Celsius for up to one year. This study aimed to investigate the superiority of repeated blood sample collection from tail vein of mice through vacuum blood collection system and eyeglasses magnifier. Experimental group in comparison with the conventional blood sampling method.

Conventional group, by beginners and experts respectively, collected blood volume and sampling duration were similar between two groups for experts, however, increased collected blood volume and shorter sampling duration were seen in experimental group compared with the conventional group for beginners. Higher success rate was also seen in the experimental group compared to the conventional group for beginners. This blood sampling method is easy to master and has a high success rate.

The number of failed puncture could be reduced to a compared that of using traditional method. Moreover this procedure only causes minimal injury to mice, it is just the tail tape of the mice without the need of anesthetics, that influence of stress response in anesthetics on the blood sample could be avoided.