Subcutaneous adipose tissue biopsies are very important for research and health because they can reveal mechanisms of adipose tissue related to the disease. In this paper we describe a technique for obtaining subcutaneous adipose tissue biopsies in the abdominal area. To obtain such samples, researchers and physicians use either a needle-based technique or a surgical-based technique.
However, it is important to note that the surgical technique provides a more complete overview of the biological indices in white adipose tissue compared to the needle-based technique, which may lead to misdiagnosis. This is true, for example, for histological analysis, which is vital for both research and health purposes. Overall, it is important to note that the surgical technique has been performed in both men and women and can be safely performed in the bedside.
The participant undertaking a surgical fat biopsy must undergo an eight hour fast and refrain from exercise, excessive stressors, alcohol, as well as active and passive smoking in the 72 hours prior to the biopsy procedure. These precautions are meant to minimize the risk for misleading results when the white adipose tissue sample is analyzed. We first prepare the materials that are needed for the adipose tissue biopsy procedure.
On a wheeled surgical Mayo we position a sterile surgical sheet. The materials are placed on Mayo and are the following. One pair of operating scissors, straight, 15 centimeters.
One scalpel, number 11. One scalpel handle. One pair of scissors, curved, 14 centimeters.
One Mosquito forceps. One pair of tweezers Kocher. One surgical tweezers.
Povidone iodine on a sterile gauze. One suture, 4.0. One pair of scissors, straight, 11 centimeters.
One needle holder, 15 centimeters. Five sterile gauzes. One adhesive sterile gauze.
One 10 milliliter syringe with a disinfected needle. 10 mL Xylocaine, 2%no adrenaline. And one pair of disinfected surgical gloves.
On a separate bench we prepare the following materials that are needed for the tissue collection. Two Eppendorf tubes. Using a sterile needle, we open a small hole on the cap of each Eppendorf.
This is because we want to avoid the cap failure when we immerge the Eppendorf in liquid nitrogen in minus 190 degrees Celsius. One tube in which we put five mL of formalin, 10%One small container with liquid nitrogen, in minus 190 degrees Celsius. We need this to immediately immerse the Eppendorf tubes containing the tissue to ensure tissue's integrity until final deposition.
Following preparation of all materials and consumables, we position the patient on a surgical bed in a supine position. The surgeon's position is on the one side of the surgical bed. The surgeon first performs disinfection of the abdominal region using povidone iodine, 15 centimeters around the point of the incision.
10 mL of Xylocaine, 2%no adrenaline, is then injected in the point of the incision for local anesthesia. A sterile surgical field is then positioned in the area. Once this is completed, we confirm that local anesthesia has been achieved.
This requires approximately three to five minutes. Thereafter, the surgeon connects the scalpel number 11 with the scalpel handle and performs an incision of the skin and the subcutaneous tissue until the underlying adipose tissue is revealed. The incision is approximately two to two and a half centimeters, and it is performed three to five centimeters away from the navel.
Thereafter, with a pair of operating scissors, straight, 15 centimeters, the surgeon removes the subcutaneous tissue. Once the adipose tissue is revealed, it is captured with a pair of tweezers and a pair of curved scissors, 14 centimeters. Then the adipose tissue is prepared and cut.
The total amount of adipose tissue removed depends on the analysis that will be performed. Based on our experience, approximately one gram of adipose tissue will be enough for the purposes of most histological and gene expression analyses. Once the adipose tissue is removed, the surgeon places sterile gauzes on the incision area for approximately 30 seconds to ensure hemostasis.
Once hemostasis is confirmed, the surgeon captures a 4-0 suture with a 14 centimeters needle and the skin with the surgical tweezers until subcutaneous tissue is visible. The suture needle enters the skin towards the subcutaneous tissue while the skin and subcutaneous are then brought together. The suture needle then follows and continues zig-zag technique into the subcutaneous tissue until being driven externally off the skin.
This continues until the skin incision is closed. Finally, the suture tying is done externally. Usually the stitches fall off within eight to 12 days, and this whole technique reduces the possibility of a post-operation scar on the skin.
The trauma is then cleaned with saline, and it is covered with adhesive sterile gauze. You may have noticed that we did not use the tweezers Mosquito. This instrument would be used in the case that the vessel is bleeding.
If so, the vessel is captured with a tweezers Mosquito to ligate and close it until achieving hemostasis. Remember that for our purposes the sample that we collected weighed approximately one gram. The collected tissue is cut into three pieces and weighed 350 milligrams, 150 milligrams, and 500 milligrams.
The 350 milligram sample is placed into an Eppendorf tube and will be used for protein levels analysis. The 150 milligram sample is placed in another Eppendorf tube and will be used for mRNA expression analysis. These two Eppendorf tubes are immediately immersed in a small container with liquid nitrogen at minus 190 degrees Celsius to ensure the integrity of the samples until final deposition in a minus 80 degrees freezer.
Finally, the 500 milligram sample is immersed in a tube containing 5 mL of formalin, 10%and will be used for histological analysis. Our technique is based on a non-diathermy method. We perform hemostasis by using sterile gauzes in order to eliminate the risk for a skin lesion, such as a scar after the surgery.
Overall, our non-diathermy method has insignificant side effects. Indeed, we performed in this study a total of 115 biopsies and we occurred only three excessive bleedings. These occurred in the second day following the biopsy procedure.
We treated these individuals by reopening the trauma, draining, applying hemostasis, and placing surgical stapling. No further complications were observed and normal healing occurred in the following days. Finally, it's important to note that three months after each biopsy procedure for all subjects no side effects were observed, including skin scars.
Our non-diathermy surgical biopsy technique showed minimal side effects, and it's proposed to be used when a complete overview of the biological indices of white adipose tissue is required.
