We have a project where we collect blood samples from people, with vacutainers. We add aprotinin to some of the vacutainers before blood drawing, so after centrifugation in room temperature, we obtain serum with and without aprotinin. Only with the serum with aprotinin, we sometimes have serum with jelly consistency after centrifugation which makes it really difficult to pipette. I once even had one vacutainer with jelly consistency and one with normal consistency, from the same individual's sample. What can be the cause of this, is it normal, and how to avoid this? Thanks in advance!
What is the time difference of serum separation. initially its Jelly consistency, later it normally becomes normal consistency. if we wait for the time of conversion you shouldnt have issues. all samples processed late might be giving normal consistency and those drawn and having less time gap show the jelly consistency.
the sample showing both results if we wait there is a possibility of jelly consistency becoming normal. have No idea on the difference.
Blood clotting is a pathway that depends on the activity of proteases and thus aprotinin as a protease inhibitor can inhibit clot formation (as necessary for the isolation of serum) or clot lysis (plasmin). The isolation of serum requires that the blood clot along with RBCs forming a precipitate that can be sedimented via centrifugation. Aprotinin could be acting on the protease-sensitive clotting cascade or in the protease-sensitive clot lysis reaction, we don't know which. The jelly consistency could be inhibition of clotting, or residual plasmin activity after formation of the clot. - What to do? Clotting factors are consumed in the clotting reaction, so if you need aprotinin to act in your sample but without interference of clotting or lysis, then, add aprotinin after isolating serum that contains no clotting factors nor plasmin. That way, samples are equally comparable in regards to serum-isolation. Otherwise you have two samples that are different in more than one variable:
Not jelly consistency: Sample 1- Serum without aprotinin (non altered clot formation/lysis).
Jelly consistency: Sample 2- Serum with aprotinin (altered clot formation /clot lysis)
Not jelly consistency: Sample 2- Serum with aprotinin (not altered clot formation /nor clot lysis)
Your only different variable needs to be aprotinin. However, you have an extra variable which is jelly consistency due to interference with clotting / lysis. It's best to add aprotinin after isolating serum that should NOT have jelly consistency.
Article Aprotinin can inhibit the proteolytic activity of thrombin. ...
Adding aprotinin to vacutainers damages the vaccum. Add aprotinin after isolation of serum, it's more practical.
Dear all,
Thanks a lot for your answers. After talking to our collaboration partner, we realized that it is a temperature issue with Serum-Gel vacutainers. So as Michael Durairaj S said, if we wait long enough, the temperature will go up a little and we will not have that much gel.