Hello everyone,
During the site visit on 3/27/2023, we discussed with Pat and Jessica about making blood clot and the clot delivery tubing to be used. PE50 tubing is commonly used to insert the clot delivery tubing into the MCA in the mouse and rat clot embolic stroke model. The PE50 tubing OD (0.99 mm) is too large and thus must be thinned down to 0.3-0.4 mm for the rat embolic model, as shown in the figure below. The thinning/extrusion technique via heating requires "significant" training to ensure a smooth extrusion.
As an alternative, a company called DOCCOL (www.dccol.com) produces a 0.36 mm OD tubing, as shown in the picture below. This microtubing may directly be used for the clot MCA embolus delivery purposes, eliminating the need for the "time consuming" thinning/extrusion technique. DOCOOL also sells a 0.22 mm OD tubing that may be used for the mouse clot delivery in the mouse embolic stroke model.
Dr. Lyden asked a question about whether the DOCCOL 0.36 mm OD is too small to delivery a clot that is big enough to occlude the MCA. Our team will make different sizes of clots and then try to pass them through the Doccol catheter (s). We will report the results as soon as we have them.
Meanwhile, please send us your questions, so we can answer them during our testing, e.g., making different types/sizes of clots.
Thank you!
Bingren
2 Fr silicone catheter
What is the product number for the 2 Fr silicone catheter? Can we get its detail information?
We received Doccol PI-218 microcatheter for mice or Doccol PI-267 microcatheter for rats. I don't think it could be feasible to deliver the clots. It can damage ICA. I am also not sure the clot can be loaded in these catheters due to its internal diameter. I will give you the output if we can.
clot model
Hi Khan, I agree with that the PI catheter is too hard that may damage the ICA when using it directly. For that reason, we are trying to use a silicone-coated PI tubing as suggested in our protocol: "The clot-loaded silicone-coated Doccol PI-218 microcatheter for mice or Doccol PI-267 microcatheter for rats will be introduced into the ECA lumen through a small ECA incision." The reason to test the PI tubing is because of its larger ID, compared to that of PE tubing.
An alternative way is to use Doccol PE-SC1-360-200-1500 for the rat model. We have tested and shown that this PE-SC1-360-200-1500 tubing can suck the washed PE50 clot from the end of the clot into this tubing as shown below. We will test the silicone-coated PI tubing, the PE tubing without silicone coating, and extruded PE50 tubing to delivery a washed PE50 clot as soon as our rat clot model protocol is approved by the UCSD IACUC.
We will report the results as soon as possible.
Clot model
Hello Bingren,
Doccol PI-218 microcatheter for mice or Doccol PI-267 microcatheter for rats have not silicone-coated. So, I thought it would also work for mice and rats, so I ordered and received it. But, unfortunately, after checking it carefully, and found that it cannot be used at any cost in rats or mice.
How will you coat them (Doccol PI-218/267) with silicone? Will you do it in your lab or from Doccol? These have also Internal diameter issues. We are more concern about the mice clot model. However, we are not worried about the rat clot model, it will be fine with PE-10.
We are using my way with the help of PE-10, and working well. We did nicely last week and had good clot delivery in the appropriate region with dropped CBF.
coating PI catheter
Thanks, Khan. We will do the coating in the same way as for the monofilament coating as shown below. We will share our experiences as soon as we complete the testing.
blood clot
We should do our best to keep the model close to the situation of patients. It is better to use arterial blood for making the blood clot.
blood clot
Dr. Sheng,
It is up to you from where you can withdraw the blood to make the clots. We always use cardiac blood to make the clots; I prefer this way. We can draw blood from a cardiac puncture from 500-900 ul to make 3-5 PE-50 tubes 25-30 cm long. It is very easy for us. In contrast, we cannot draw blood more than 100ul from the retroorbital (eye).
blood clot
Dr. Sheng,
It is up to you from where you can withdraw the blood to make the clots. We always use cardiac blood to make the clots; I prefer this way. We can draw blood from a cardiac puncture from 500-900 ul to make 3-5 PE-50 tubes 25-30 cm long. It is very easy for us. In contrast, we cannot draw blood more than 100ul from the retroorbital (eye).
Yale clots
This is really nice of you to illustrate all the steps. Personally, i think its really important to draw the blood into the Eppendorf that contains the fibrinogen, mix it VERY briefly, and then draw up into the PE50. It is CRUCIAL to inclubate at 37C to get the clotting reaction to go normally. If not, i would expect the clots to be friable and not likely to get all the way up to the MCA.
Yale clots
This is really nice of you to illustrate all the steps. Personally, i think its really important to draw the blood into the Eppendorf that contains the fibrinogen, mix it VERY briefly, and then draw up into the PE50. It is CRUCIAL to inclubate at 37C to get the clotting reaction to go normally. If not, i would expect the clots to be friable and not likely to get all the way up to the MCA.
clot model
Thanks! Pat, for your guidance. Is it possible to inject the human fibrinogen solution into the mouse or rat circulation via either IV or intra-artery, and then to withdraw the blood after a couple of minutes of circulation?