Direct drug delivery to the kidney, via the renal artery. In the renal research field there is a need for directed injections, to enable increased and specific, renal exposure, for efficient evaluation of drug targets. My name is Erica Dahlquist and my aim with this video is to share my experience, in how to do injections directly into the renal artery.
I will now present to you, how to do injections, directly to the kidney via the aorta. To start with, I can say that I always give the mouse, both and of course, pre-surgery. After opening the abdominal cavity, I put in a moist folded compress, to push all other organs aside, so that I get a good view over the surgery area.
Try to constantly keep the tissues moist, by adding saline into the surgery wound, to protect the tissues from drying. This also helps keeping the tissue elastic, and minimize the risk of damage, while performing surgery. Use retractors to have a good overview of the surgery area.
These two pictures are the same. In the right picture, I have tried to draw the structures. The pink area is the aorta.
I will first put a ligature cranial from the left kidney. With this, I will later lift the aorta to momentarily, occlude the blood flow while doing the injection. As you can see, there is a branch from the aorta, going to the lift in the picture.
In order to avoid pushing our injection this way, I need to put the ligature beneath it. This leaves a quite narrow area to work in. With two forceps, you start to clean the aorta from surrounding tissues.
Try not to pinch any structures, and work your way in, by gently stretching and pooling the tissues. Around the vessels, there are plenty of nerves that are not easy to discover. Just keep this in mind, since hurting the nerves could cause paralyzes or other issues, post surgery.
As mentioned before, I tried to constantly add saline, to protect the tissues from drying. I will now place the first ligature underneath the aorta. When the ligature is in place, I will leave it there while continuing to the next step.
And of course, continue to moist on the tissue. I have now moved the camera, and what you see is the structure is Cordell from the kidney. After adding fluids, I start to dissect my way down to clean the aorta the same way as before.
The aorta is in this position, very close to the abdominal vein. And you have to be very careful not to break the vein. Try to work close to the kidney, to have a short distance as possible to the renal artery.
To make some more space in the area, you can gently move the suture a bit up and down, when it's in place. This time I will also put another ligature around the aorta and make a loose knot. This I will use to secure and close the aorta, around the catheter, before injecting.
When all ligatures are in place, it's time for the actual injection. Start by stretching the lower and then the upper ligature, to occlude the bloodstream and direct the injected fluid to the kidney alone. With help from an acupuncture needle, I guide the rounded tip of the catheter into the aorta, and secure it with a single knot on the ligature.
This way it will move or leak during injection. I now inject 50 microliters of fluids, and you can see clearly how the kidney turns pale. After injecting, you can choose to either give some circulation back to the kidney, by shortly, loosen the tension in the upper ligature.
Like I do in this setting. Or you can keep on with the surgery, without giving blood flow back. If you give blood flow back, you ameliorate ischemia a bit.
At the same time, whatever you injected, will be rinsed out earlier through the renal vein. And here you see the blood entering back into the kidney when I loosened the ligature. After tightening the upper ligature again, it's time to withdraw the catheter, suture the aorta, and give it back full of circulation again.
I start by removing the suture, holding the catheter. And then I withdraw the catheter. I suture the entry hole with a single stitch.
After suturing the hole, you first loosen the lower ligature, and then very slowly loosen the upper one. If there is a leakage, you can tighten the ligature again, wait for a few seconds and try again. If the suture is in place, it usually stops.
So have faith. I always try to test the strength, by pushing the area, and look for pulsations, to secure that the blood flow is going back to normal. When everything is good, you can cut the threads, and take away the ligature.
Remove the compress and try to gently push the intestines back in place. Give back some fluids and stitch the abdominal cavity, together before closing the skin with metal clips. In this study labeled MSCs were injected into the left renal artery.
It clearly shows a significantly increased engraftment of cells, in the left kidney compared to the right kidney. In short, we can conclude that we do have an established method for delivering formulations directly to the kidney, without renal damage. The method is usable for any kind of formulation, and it has the advantage of requiring a smaller amount or dose volume, to reach the same level of renal exposure, as compared to systemic administration.
