If you can stand the guy's voice, here's a little extra information:
http://www.youtube.com/watch?v=PCDStwS6Is8
Interestingly, for people with some coagulopathies, this type of material might not activate the coagulation cascade (Hemophilia A, Hemophilia B, Inhibitor mutations, Factor 5 Leiden). For others this
miiiight do such a thing (Factor 13th deficiency, Lupus Anticoagulant, van Willebrand's disease...)
Having something to act as skin to stop bleeding, may be useful though.