Dr. Joe Wu

Smoking marijuana could be bad for your heart, but there is an unusual remedy

/ Kevin McCormack / 2 Comments

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Smoking medical marijuana: Photo courtesy Elsa Olofsson

Millions of Americans use marijuana for medical reasons, such as reducing anxiety or helping ease the side effects of cancer therapy. Millions more turn to it for recreational reasons, saying it helps them relax. Now a new study says those who smoke marijuana regularly might be putting themselves at increased risk of heart disease and heart attack.

There has long been debate about the benefits versus the risks for using cannabis, with evidence on both sides to support each position. For example some studies have shown taking oral cannabinoids can help people cope with the nausea brought on by chemotherapy. Other studies have shown that regular use of marijuana can cause problems such as marijuana use disorder, a condition where the user is showing physical or psychological problems but has difficulty controlling or reducing their use of cannabis.

Now this latest study, from researchers at Stanford Medicine,  shows that THC, the psychoactive part of the drug, can cause inflammation in endothelial cells. These are the cells that line the interior of blood vessels. When these cells become inflamed it can cause a constriction of the vessels and reduce blood flow. Over time this can create conditions that increase the risk of heart disease and heart attack.

The researchers, led by Dr. Joe Wu, began by analyzing data from the UK Biobank. This included information about some 35,000 people who reported smoking marijuana. Of these around 11,000 smoked more than once a month. The researchers found that regular marijuana smokers:

  • Were significantly more likely than others to have a heart attack.
  • Were also more likely to have their first heart attack before the age of 50, increasing their risk of subsequent attacks.

The team then used the iPSC method to create human endothelial cells and, in the lab, found that THC appeared to promote inflammation in the cells. They also found signs it created early indications of atherosclerosis, where there is a buildup of fat and plaque in the arteries.

They then tested mice which had been bred to have high levels of cholesterol and who were given a high fat diet. Some of the mice were then injected with THC, at a level comparable to smoking one marijuana cigarette a day. Those mice had far larger amounts of atherosclerosis plaque in their arteries compared to the mice who didn’t get the THC.

In a news release, Dr.Wu, the lead author of the study, said: “There’s a growing public perception that marijuana is harmless or even beneficial. Marijuana clearly has important medicinal uses, but recreational users should think carefully about excessive use.”

On the bright side, the team also reported that the damage caused by THC can be stopped by genistein, a naturally occurring compound found in soy and fava beans. The study, in the journal Cell, also found that genistein blocked the bad impact of THC without impeding the good impacts.

“As more states legalize the recreational use of marijuana, users need to be aware that it could have cardiovascular side effects,” said Dr. Wu. “But genistein works quite well to mitigate marijuana-induced damage of the endothelial vessels without blocking the effects marijuana has on the central nervous system, and it could be a way for medical marijuana users to protect themselves from a cardiovascular standpoint.”

CIRM funds clinical trials targeting heart disease, stroke and childhood brain tumors

/ Kevin McCormack / Leave a comment
Gary Steinberg (Jonathan Sprague)

Heart disease and stroke are two of the leading causes of death and disability and for people who have experienced either their treatment options are very limited. Current therapies focus on dealing with the immediate impact of the attack, but there is nothing to deal with the longer-term impact. The CIRM Board hopes to change that by funding promising work for both conditions.

Dr. Gary Steinberg and his team at Stanford were awarded almost $12 million to conduct a clinical trial to test a therapy for motor disabilities caused by chronic ischemic stroke.  While “clot busting” therapies can treat strokes in their acute phase, immediately after they occur, these treatments can only be given within a few hours of the initial injury.  There are no approved therapies to treat chronic stroke, the disabilities that remain in the months and years after the initial brain attack.

Dr. Steinberg will use embryonic stem cells that have been turned into neural stem cells (NSCs), a kind of stem cell that can form different cell types found in the brain.  In a surgical procedure, the team will inject the NSCs directly into the brains of chronic stroke patients.  While the ultimate goal of the therapy is to restore loss of movement in patients, this is just the first step in clinical trials for the therapy.  This first-in-human trial will evaluate the therapy for safety and feasibility and look for signs that it is helping patients.

Another Stanford researcher, Dr. Crystal Mackall, was also awarded almost $12 million to conduct a clinical trial to test a treatment for children and young adults with glioma, a devastating, aggressive brain tumor that occurs primarily in children and young adults and originates in the brain.  Such tumors are uniformly fatal and are the leading cause of childhood brain tumor-related death. Radiation therapy is a current treatment option, but it only extends survival by a few months.

Dr. Crystal Mackall and her team will modify a patient’s own T cells, an immune system cell that can destroy foreign or abnormal cells.  The T cells will be modified with a protein called chimeric antigen receptor (CAR), which will give the newly created CAR-T cells the ability to identify and destroy the brain tumor cells.  The CAR-T cells will be re-introduced back into patients and the therapy will be evaluated for safety and efficacy.

Joseph Wu Stanford

Stanford made it three in a row with the award of almost $7 million to Dr. Joe Wu to test a therapy for left-sided heart failure resulting from a heart attack.  The major issue with this disease is that after a large number of heart muscle cells are killed or damaged by a heart attack, the adult heart has little ability to repair or replace these cells.  Thus, rather than being able to replenish its supply of muscle cells, the heart forms a scar that can ultimately cause it to fail.  

Dr. Wu will use human embryonic stem cells (hESCs) to generate cardiomyocytes (CM), a type of cell that makes up the heart muscle.  The newly created hESC-CMs will then be administered to patients at the site of the heart muscle damage in a first-in-human trial.  This initial trial will evaluate the safety and feasibility of the therapy, and the effect upon heart function will also be examined.  The ultimate aim of this approach is to improve heart function for patients suffering from heart failure.

“We are pleased to add these clinical trials to CIRM’s portfolio,” says Maria T. Millan, M.D., President and CEO of CIRM.  “Because of the reauthorization of CIRM under Proposition 14, we have now directly funded 75 clinical trials.  The three grants approved bring forward regenerative medicine clinical trials for brain tumors, stroke, and heart failure, debilitating and fatal conditions where there are currently no definitive therapies or cures.”