Finally, heparin may have many other unrecognized effects—both protective and harmful—arising from its heterogeneous structure. As noted, unfractionated heparin is composed of a mixture of distinct biologically derived (i.e., porcine intestinal mucosae) heparan sulfate polysaccharides, which on balance not only is enriched in a pentasaccharide sequence necessary for AT3 activation (and thus anticoagulation) but also displays a wide variety of other sulfation sequences. These non-anticoagulant sulfation sequences allow heparin binding to various growth factors, potentially exerting both organ-protective (46, 49) and organ-harmful (14, 20) effects.