Healing the heart after a heart attack is a tough venture. Stem cell treatments have shown definite glimmers to success, but a lack of consistency is a persistent problem. Kick-starting the resident stem cell population in the heart is also a possibility but no single strategy has emerged as a tried and true method to treat a sick heart. Tissue engineering remains an engaging possibility and in the laboratory of Amit Patel at the University of Utah, the possibilities push the boundaries on your imagination.
Patel and his colleagues have been hammering at this problem for decades. The problem is how you replace dead tissue in a beating heart with live tissue that can beat in sync with the rest of the tissue. Unfortunately, you cannot ask the heart to take a vacation to help heal itself. Presently, Patel said that “The doctors say, ‘We’ll give you the beta blocker and the aspirin and the Lipitor and we can just hope to maintain you. But short of them getting worse or getting a heart transplant, there’s [sic] not too many options.”
Patel’s work, however, might change all that. He is presently leading trials on an experimental technology that might repair scarred heart tissue and even arrest or, perhaps, reverse heart failure.
His procedure is in a Phase 1 FDA clinical trial. The trial is designed to mix a powder that consists of a mixture of proteins and molecules isolated from heart muscle with saline or water, inject this mixture into the dead portions of the patient’s heart by means of a catheter, and then wait three to six months to determine if the patient’s heart muscle regenerates.
“Heart disease is the most common cause of death in the world, and the most prominent problem is heart failure,” said Tim Henry, the director of cardiology at the Cedars-Sinai Heart Institute. “Effectively, it’s basically one of the biggest problems in the U.S.” Curing the heart with stem cells is, according to Henry, “within our reach,” and Patel, is, to Henry’s thinking, “is clearly one of the most experienced stem cell people in the country”
After a heart attack, the dead regions of the heart form a scar that does not contract, does not conduct electrical impulses, and the rest of the heart has to work around. Reviving the heart scar, shrinking it or reprogramming it to live again has been the dream of stem cell therapy and gene therapy research. However, according to Patel, these venues have not proven to be very good at regenerating dead scar tissue.
Patel, however, noted that “endocardial matrix therapy” would probably be cheaper than stem cell or gene therapy, since it requires an off-the-shelf product that has the advantage of being mass-produced, is easily delivered clinically speaking, and can be easily commercialized and marketed.
This leads to a new question: “What is “extracellular matrix therapy?”
The extracellular matrix is a foundational material upon which cells sit. Extracellular matrix or ECM also provides the glue that attaches cells to each other, layers of cells to each other, and binds tissues together. In Patel’s rendering, ECM consists of everything in our tissues and organs except the cells. If you were to break down the ECM to its parts, you would end up with a concoction of proteins, minerals and a whole cadre of small molecules that can provide a scaffold for cells, nerves and vessels to attach.
To emphasize the importance of the ECM for the heart, Patel said: “A heart without scaffolding is just a bag of cells.” That pretty well nails it.
The ECM also plays a very important signaling role, since it acts as a repository for important signaling molecules that tell cells to grow and develop or divide and heal. The ECM is the milieu in which cells live and grow.
The foundational importance of the ECM gave Patel a revolutionary thought: to heal the heart the matrix has to come first before the cells can follow.
The powder form of heart-specific ECM was developed by scientists at the University of California, San Diego. This group removed the heart muscle from pig hearts, washed away all the cells, and then freeze-dried the remaining ECM into a powder. Using this work as their template, Patel and his team have also devised a protocol to make ECM power from human heart muscle.
When you add water or saline to this ECM powder, it forms a gooey substance called a “hydrogel.” This hydrogel has been called “VentriGel” and it is as flexible as native tissue. Hydrogels are the mainstay of tissue engineering experiments. VentriGel and hydrogels like it can mimic the molecular environment in which cells normally grow and develop. Fortunately, VentriGel has already been shown to successfully reduce scar tissue in the hearts of rats and pigs. To test VentriGel in human patients, Patel and his co-workers can come to the forefront.
Patel recruited a Utah woman who had suffered a heart attack six months ago. This episode reduced her overall heart blood pumping ability from 60 percent (normal) to less than 45 percent (well below normal). Patel and his colleagues made a virtual model of the inside of the patient’s heart to determine where her dead heart muscle resided. Then they marked out 18 different injection sites, and used a catheter to inject the matrix into her heart. The matrix injection procedure took less than two hours.
“This first patient was able to be done awake and safe and she’s already back to work,” Patel said. “She went home the next day.”
Patel plans to treat up to eighteen patients with his experimental procedure. Additionally, cardiologists at the Minneapolis Heart Institute in Minnesota, the only other site approved to test the new technology, performed the procedure on a second patient on Tuesday.
The risks of this procedure are well-known: When hydrogels are directly injected into the heart muscle, they can unintentionally interrupt the electrical conduction of the heart and cause irregular heartbeats. Also, the injected matrix can travel to other parts of the body where it can form a clot that could lead to a stroke. Clots in other parts of the body can also cause the patient’s blood vessels could collapse.
“If you go through all the bad things that could happen, you’d be so depressed, you’d be like, ‘Really? You found somebody to go through this?'” Patel said. “The key is that the team that we have here, and many of my collaborators, we’re all at that same level of healthy enthusiasm mixed with extreme paranoia.”
All patients will be examined three and six months after the procedure out for evidence of muscle regrowth and revived heart function.
“We want to treat this before it ends up leading to permanent damage,” Patel said.
If the trial returns positive results, it will represent another step forward in a long journey to eradicate heart disease. Patel estimates, that if everything goes smoothly, the technology could become approved for clinical use within five to seven years.