Marijuana may help prevent transplant rejection

In an exciting discovery, scientists have found that THC, the active ingredient in marijuana, may delay the rejection of incompatible organs in transplant patients. While more research is necessary to determine if there are benefits to humans, the study suggests that Tetrahydrocannabinol (THC), or a derivative, might prove to be a useful antirejection therapy, particularly in situations where transplanted organs may not be a perfect match, researchers said.

"We are excited to demonstrate for the first time that cannabinoid receptors play an important role in the prolongation of rejection of a foreign graft by suppressing immune response in the recipient," said Mitzi Nagarkatti, a researcher involved in the work from the University of South Carolina School of Medicine. "This opens up a new area of research that would lead to better approaches to prevent transplant rejection as well as to treat other inflammatory diseases," Nagarkatti said. In the study published in The Journal of Leukocyte Biology, Nagarkatti and colleagues explained that they used two groups of mice that were genetically different, and transplanted skin from one group to the other. All of the mice received incompatible skin, but one group was treated with vehicle (placebo) and the other was treated with THC. The scientists observed that the rejection of the skin graft in mice that received THC was delayed when compared to the control group that only received a placebo. "More and more research is identifying potential beneficial effects of substances contained in marijuana, but a major challenge has been identifying the molecular pathways involved," said John Wherry, Deputy Editor of the Journal of Leukocyte Biology. "These new studies point to important roles for the cannabinoid receptors as targets that might be exploited using approaches that refine how we think about substances derived from marijuana," he said.