NEOMED Researchers Work To Plug Blood Vessel Leaks

ROOTSTOWN, Ohio — The human body, Dr. Charles Thodeti explains, is like a house and the cardiovascular system its plumbing. And just as not dealing with leaking or blocked pipes can spell trouble for a homeowner, faults in the blood vessels can create long-term health issues.

“If there’s a block, it leads to a heart attack. In tumors, you see a lot of leaky vessels. If there’s a leak in the eye, that can lead to blindness,” Thodeti says. “We’re trying to act as plumbers and understand the growth of blood vessels so we can repair them.”

In a research lab at Northeast Ohio Medical University, Thodeti and a team of researchers are examining a specific protein (which the school declines to identify) and its role in preventing growth and metastasis of tumors and fibrosis in the heart.

What Thodeti and his research team are studying is how that specific protein expression and function regulates blood vessel growth and structure as well as the repair of heart. This protein is found along blood vessels and helps with maintaining the integrity of the vessels.

Thodeti’s lab has found that in cancers, levels of this protein are lower in the cancerous vessels, causing the vessels to leak and stiffen the tumor. Leaky blood vessels also allow the cancer cells to escape from the tumor and metastasize in other organs such as the lungs and liver. By forcing the protein to “switch” on, vessels that surround tumors stop leaking, returning a full flow of blood.

That may seem counterintuitive, given that one of the common methods for getting rid of tumors is cutting the vessels that supply it, thus removing its source of growth. But Thodeti’s idea focuses on the fact that chemotherapy drugs used to kill tumors rely almost entirely on their delivery through blood flow.

If blood vessels to a tumor are removed and the drugs used to kill the tumor are delivered via blood, then the drugs aren’t delivered effectively as they could. And if a tumor is not killed, there is a possibility of relapse.

“We take a different route. Instead of cutting off the blood supply, we repair the leaks, restoring full blood flow, so we can efficiently deliver cancer drugs to the tumor and kill the whole tumor, as well as prevent metastasis” he explains.

Although this idea of repairing the tumor vessels is not new, most work on this area focuses on inhibiting the action of chemical factors in the blood, which in fact has been shown to stop blood flow to the tumors within hours. Thodeti’s lab focuses on the mechanical factors of this specific protein, which is critical for sensing the mechanical forces in the cell.

Modulating expression of the specific protein could also be used to repair the damage to heart tissue caused by heart attacks. When the heart stops pumping because a heart attack, blood is no longer supplied to a part of the heart and that part dies within minutes. As a result, other cells in the heart, called fibroblasts, are activated and form scar tissue to contain the damage.

“Uncontrolled activation of these cells can lead to cardiac fibrosis, or a stiff heart,” he says. “Eventually the heart becomes stiff. It can’t pump blood as efficiently and in the long run that can lead to death.”

This specific protein plays a role in activating fibroblasts. Thodeti’s research could lead to the creation of a drug that can inhibit, or possibly reverse, the effects of the fibroblasts.

Recent grants of $2.5 million, including from the National Institutes of Health and the American Heart Association, have helped fund Thodeti’s research at NEOMED. Among the technologies funded are hydrogels that mimic the stiffness of heart and vascular tissue to help in Thodeti’s research. Cells from blood vessels and heart are placed on the gels and monitored to measure their growth and function.

“Everyone studies the soluble factors to target pathological conditions, however, the mechanical factors are equally as important,” says Ravi Adapala, a doctoral candidate. “For that, we prepare gelatin hydrogels that mimic the stiffness of the tumor and polyacrylamide gels that mimic the stiffness of normal and diseased tissues.”

The innovative process of growing the cells on these gels is complex and requires attention to minor details. Therefore, the entire process takes several days. Having these gels is crucial to the research, Thodeti says, because it can be created to exact specifications, eliminating some of the variables found with in vivo testing – or testing on live animals. “If you want to see the heart-level function, [you can use in vivo] but if you want to go deep and understand the molecular mechanisms, you need to go to a test tube. There is no other way.”

To conduct this research, Thodeti works with a team of researchers varied in their experiences. From doctoral and postdoctoral researchers to medical student assistants, and from research technicians to microsurgeons, each member of the lab plays an important role.

When it comes to testing the processes in mice, research technician Nina Lenkey is responsible for ensuring that the colony is fit for testing and that they won’t invalidate any results.

“I take a DNA sample from the animals, isolate the DNA and run an experiment to make sure they have the right DNA,” she says from her workstation in the lab. “We have wild-type mice that are just basic mice. Then we have a knockout version, which does not express the specific protein.” We are also trying to create cell specific knock out mice of the specific protein to be used to further our study.

Beyond just gaining the experience of participating in lab work, a group of medical student assistants gain knowledge that could help them in their fields. Harshitha Dudipala and Shareena Shaik, two upcoming medical students who have been on the team about four weeks, are first learning the techniques necessary for the research.

“We started with techniques for tissue sectioning, staining and imaging to understand the specific protein function in heart repair,” Shaik says.

Adds Dudipala, “It’s mostly been getting familiarized. My particular work is with pericytes, looking at the expression of the specific protein and how it relates to vessel growth in cancer.”

Priya Midha, third-year medical student together with a post-doctoral fellow, Dr. Anantha Kanugula, studies the interaction of this specific protein with growth factors to regulate the formation of blood vessels. Because abnormal vasculature can cause tumors to metastasize, or spread throughout the body, such research can be applied in the future to develop new cancer therapies that prevent tumor metastasis.

With plans to be a surgeon, Ashot Minasyan, a cardiologist by training and the lab’s expert microsurgeon, says working on the hearts of lab mice – significantly smaller than those of humans – is a challenge that is helping to fine-tune his motor skills.

Then, there’s the technology. In addition to the hydrogel models, the researchers are working with echocardiography to measure how the heart functions and contrast echoes to measure the flow of blood. Another technique is used to mimic the stretch of the beating heart on cells with and without the specific protein, allowing researchers to understand the molecular mechanisms of blood vessel growth and structure in tumors or remodeling of the heart issue after heart attacks.

The next step for Thodeti’s research will take him nearly 400 miles to Philadelphia. Over the next year, he’ll work with a team there using newly developed organ-on-chip models.

In this system developed at Thodeti’s alma mater, Harvard University, cells from human organ tissues are placed on chips about the size of a USB stick. Researchers can than mimic the mechanics and responses of human organs, bypassing the need for animal test subjects and producing more accurate results, since those animal systems don’t match exactly with human ones.

VIDEO: ‘3 Minutes With’ Dr. Charles Thodeti

Pictured at top: Research technician Nina Lenkey genotypes the mice in the lab’s colony.

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