Blood Spreading effect on a fabric material

Did you ever find a way? I am trying to do this with a tomato

A simple way to fake it:

1. Fabric layer on the bottom
2. Red layer on top
3. Experiment with the overlay, multiply, linear burn blend modes and color to get the look you like
4. Animate a couple of masks to get the blood shape to grow
5. Add a new layer for fractal noise on the top and adjust the settings to get an animated blotchy gradient that fades from white to black or black to white
6. Pre-compose the Fractal noise layer and then use that as a luma track matte for the red blood layer
7. Add roughen edges and maybe Bevil Alpha

You get something like this in a couple of minutes:

You can see almost everything I have done in the comp. The animated masks with feathered edges expand the size of the blood, the fractal noise pre-comp acts as a mask to gradually reveal the blood, the blend mode makes the blood appear to be part of the fabric, and animated roughen edges and the bevel alpha give some motion and viscosity to the blood.

That should get you started.