The effects of shark cartilage on the immune system were also reported in two studies that used the same purified protein fraction that had exhibited the most immunostimulatory effects when tested.[8,9] One study explored the effects of this fraction on tumor immune response by observing the infiltration of this fraction on CD4 and CD8 lymphocytes in a murine tumor model. An increase in the ratio of CD4/CD8 lymphocytes was seen in tumor-infiltrating lymphocytes but not in peripheral blood lymphocytes. The second study exploring immune system response measured antibody response, cytotoxic assay, lymphocyte transformation, and intratumor T-cell ratio in mice. The fraction exhibited the ability to augment delayed-type hypersensitivity response against sheep red blood cells in mice and to decrease the cytotoxic activity of natural killer cells. In addition, this fraction showed a strong inhibitory effect on human brain microvascular endothelial cell proliferation and migration in the fibrin matrix.
Additional in vivo studies of the antitumor potential of shark cartilage have been published in the peer-reviewed scientific literature.[10,11,12] In one study, oral administration of powdered shark cartilage (no brand name given) was shown to inhibit chemically induced angiogenesis in the mesenteric membrane of rats. In another study, oral administration of powdered shark cartilage (no brand name given) was shown to reduce the growth of GS-9L gliosarcomas in rats. It was reported in a third study that oral administration of two powdered shark cartilage products, Sharkilage and MIA Shark Powder, did not inhibit the growth or the metastasis of SCCVII squamous cell carcinomas in mice.
A large number of laboratory and animal studies concerning the antiangiogenic potential of cartilage have been published.[2,10,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33] Overall, these studies have revealed the presence of at least three angiogenesis inhibitors in bovine cartilage [14,15,18,19,22,24] Reviewed in [17,34] and at least two in shark cartilage.[2,10,26,27]