Trio of grants to help unlock liver treatments
Associate Professor Salman Khetani describes the human liver as the body’s critical chemical factory. It filters out the nutrients from what we eat and drink, it helps remove toxins from the body through waste, it stores glycogen to keep our blood sugar up even when we are not eating, and it recycles our blood by breaking down old and damaged blood cells.
The liver also serves as a filter for any drugs or medicine we put into our bodies, often taking the brunt of the negative side effects. Because the liver is such a complex and diverse organ, modern medicine’s only way of treating a failing liver is with a transplant.
Khetani is hoping to advance our understanding of this vital organ and advance our way to treat several medical disorders centered on the liver through three grants from the National Institute of Health that total more than $2.2 million.
The first grant has Khetani’s Microfabricated Tissue Models Lab partnering with Associate Professor Ramille Shah to use his lab’s innovative droplet microfluidics techniques with Shah’s 3D biomaterial printing capabilities to engineer a comprehensive liver tissue model.
Khetani explained he has created a device where researchers can add cells with collagen and combine them together with oil in a cold environment. When they come out of the cold and are heated up, they create a miniature three-dimensional gel, like a Jell-O mold. The technique allows the scientist to be very precise with what is added and grows inside the gel.
The human liver is actually made up of three compartments, including the hepatic, vascular, and biliary. Most 3D tissue models of the liver only include the hepatic tissue, the part of the liver that processes food and beverages. But by using the droplet microfluidics gel as a bioink for a 3D printer, Shah and Khetani believe they can make a more accurate model.
These models could then be used to test new drugs to see if they are safe for human use or help as a treatment option for end-stage-liver failure patients, whose only present treatment option is a liver transplant. Khetani noted most patients can only live for a few days after their livers completely shut down.
“No one has 3D-printed a liver with all three major compartments,” he said. “In the future, we could implant them into animals and see if that could keep people alive who have end-stage-liver failure,” Khetani said. “It may not replace a transplant, but it could keep someone alive while they wait for one.”
The second grant, which Khetani received along with Pharmacology and Regenerative Medicine Assistant Professor Kostandin Pajcini, is from the NIH’s National Heart, Lung, and Blood Institute and aims to open up new ways to treat patients with blood disorders such as leukemia.
As Khetani explained, patients with blood disorders often have to have their bone marrow destroyed during treatment because if they do not, the defective blood cells will return. Once a patient’s bone marrow is removed, they need a bone marrow transplant from a donor. This process is incredibly painful and often is ineffective because all of our body’s blood cells come from a single stem cell known as the hematopoietic stem cell.
“It turns out that in adults, there aren’t that many of these hematopoietic cells, so when they do a bone marrow transplant, they are just hoping one of them will make it into the patient and repopulate the whole blood,” Khetani said.
However, when humans develop in the womb before they have bones or bone marrow, our livers expand hematopoietic stem cells to supply the fetus with blood. So, Khetani and Pajcini hypothesized that they could create an in vitro model of the liver using donated adult tissue to grow these base blood stem cells and freeze them before they transform into white or red blood cells.
“We have some really nice preliminary data on this concept, so this grant will allow us to see if we can show this concept in vitro and then scale it up to create an abundant supply of these valuable cells, which could be frozen and used for people with these disorders instead of the traditional bone marrow transplant,” Khetani said.
The final grant, which has Khetani partnering with Associate Professor Yang Dai, Molecular Genetics Professor Brad Merrill, and Pharmacology and Regenerative Medicine Professor Jalees Rehman, will fund the creation of a blueprint for how to develop stem cells that can be used to grow liver tissue and models. Khetani said researchers previously discovered how to take skin cells and reprogram them into human-induced pluripotent stem cells (iPSC), which can be further transformed into a liver, heart, or other cell type.
This process is hard to reproduce, he explained, and every lab has its own favorite techniques and ways of doing things. The National Science Foundation realized that for these techniques to be reproducible and scalable, the community needs a standardized process to follow.
Khetani said his group received funding because their idea was to combine three fields to solve this reproducibility issue, including the droplet microfluidics from his lab, Merrill’s expertise with genetic editing with CRISPR, and Rehman and Dai’s use of computation biology to analyze the iPSCs 30,000 genes.
“This is a high-risk, high-reward kind of mechanism,” Khetani said. “The cells have tens of thousands of genes and hundreds of transcription factors all working in coordination, so it would be impossible for us to try and control all that. But you have some key master transcription factors that drive other factors, so if we can get to the root of the tree, we can control how all the branches will form down the line.”
In addition to his faculty collaborators, Khetani said several PhD students are contributing to the liver work, including Grace Brown, Na Yoon Paik, Thao Nguyen, Regeant Panday, Cristiana Trinconi, Ashlin Michell, Kristen Cotton, Yang Yuan, Hannah Pennington, Shang Gao, and Xin Li.