Dr. Evgeniy Panzhinskiy is a postdoctoral fellow in the lab of Dr. James Johnson at the University of British Columbia. Originally from Khabarovk, Russia, Dr. Panzhinskiy studied the molecular mechanisms of obesity-induced insulin resistance in skeletal muscle during his PhD in Dr. Sreejayan Nair’s lab at the University of Wyoming. We sat down with Dr. Panzhinskiy to talk to him about his new project deriving beta-like cells with tunable insulin expression from human stem cells.
You’ve spent most of your time in research studying diabetes. Why are you interested in studying type 1 diabetes in particular?
Type 2 diabetes is reversible in specific patients with diet, exercise, and drugs, but there is no cure for type 1 diabetes. There is effective treatment using insulin, but the function of your insulin producing beta cells will decline no matter what you do. Fortunately, there has recently been a lot of promise in finding a cure for type 1 diabetes using stem cells or devices that control blood glucose by secreting insulin at the right time. It makes it a very exciting time to be studying the disease.
Have there been any monumental papers in the field of type 1 diabetes that have influenced your current research project?
Absolutely. In 2014, Tim Kieffer’s and Doug Melton’s groups published the first in vitro differentiation protocols for producing beta-like cells from human stem cells. When transplanted into a type 1 diabetes mouse model, these cells were able to cure diabetes. This potentially opens the road for humans, and phase 1 clinical trials are in fact in progress.
But one of the most important scientific findings from these papers is that although these beta-like cells can reverse diabetes, they are not yet truly beta cells. When we compare them to actual human islets isolated from cadaveric donors, they don’t secrete insulin as precisely. Normal human islets are able to respond to even slight changes in glucose to stop producing insulin when glucose drops down to a basal level. It’s consistent from cell to cell. With these beta-like cells it’s not consistent – some cells respond very well and others do not. Sometimes they even need higher levels of glucose to actually start secreting insulin, so they’re not as sensitive.
Nonetheless, it’s a big step. It’s the first time researchers have been able to differentiate human cells into cells that so closely resemble beta cells, and that reverse diabetes in mice when transplanted.
Do you plan to follow up this work?
Absolutely! My goal is to design and create beta-like cells derived from human stem cells that will be able to increase or decrease the amount of insulin they produce through the stimulus of light. We’re going to use CRISPR technology to specifically guide Cas9 to the insulin promoter, and fuse it to Cry2FL which dimerizes in response to blue light. The second half of the dimer will be fused to either a transcriptional activator or transcriptional repressor, which will allow for insulin expression to be increased or decreased. So Cas9 will give us the specificity of binding and light will give us the temporal resolution.
Why would you want to decrease the insulin expression of these cells?
What makes beta cells is their unique ability to produce insulin. But we and others have shown that the production of insulin makes beta cells vulnerable to stress. Specifically, the huge amount of insulin that is produced by beta cells results in ER stress, because the ER needs to fold and properly oxidize all the insulin. It’s a big workload. We believe that the ER is always on the edge of overload, and if you push it too hard, beta cells will become stressed and start dying.
The second thing is that the process of transplantation is stressful to cells. The cells are injected and travel through the bloodstream, they get trapped in new places, and they’re not properly oxygenated. You lose most of the cells in the first 24 hours after transplantation. We think that if they’re already on the edge, and then we add the stress of transplantation, it might be too much for them. Dialing back insulin could therefore be beneficial during transplantation.
How will these cells be transplanted in mice?
With mice, we can transplant the beta-like cells into the eye. It’s an accessible site and therefore easy to do, and it’s also not very invasive compared to other types of surgery. You can also monitor the cells by just looking into the eye with a microscope. Then you can shine a blue light to alter transcription.
Some people think it’s surprising that you can reverse diabetes with transplantation of these beta-like cells into only the eye, but if you think about how many beta cells you have to start with, it’s very tiny. You don’t need a lot, but you do need them to be functional. If you have a healthy individual who doesn’t have diabetes, the small number of beta cells they have will barely divide, but will last them their entire life. There’s almost no division or proliferation after the age of 18, but they last.
How will this project relate to humans suffering from type 1 diabetes?
This project has basic scientific merit. We want to learn the stages of beta cell transplantation where changing insulin expression is beneficial. For humans, some scientists think that a device in which you transplant the beta-like cells is needed. First because you want to have the least invasive surgery possible, and second for protection. Keep in mind that type 1 diabetes is an autoimmune disease that destroys beta cells. If we just give patients unprotected beta cells, they’re going to be destroyed again, so a device that is permeable to nutrients and oxygen, but non-permeable to immune cells would be ideal. If we placed the device in a spot accessible to light such as under the skin, then a blue light laser would be strong enough to penetrate and activate the cells.
Do you think you’ll see a cure for type 1 diabetes in your lifetime?
A lot of clinicians and doctors don’t think it’s going to happen in our lifetime, but as a scientist I say yes – just not in the next 5 or 10 years. I think the science is there. We just have to make sure that we don’t rush it. There’s still a lot of work to be done, and we know where to go now. We just need to not let our excitement run ahead of science.
Thank you very much for your time Dr. Panzhinskiy. It’s incredible to know that this exciting research is happening here in Vancouver!
To find out more about Dr. Panzhinskiy, follow him on twitter!
