Replacement Beta-Cells From An Unexpected Source
Project Researcher: Joseph Lancman, Ph.D. – Sanford Burnham Prebys Medical Discovery Institute
A cure for diabetes will require replacing the insulin producing beta-cells that have been lost in this disease. Replacing these lost cells in patients with diabetes can be achieved through transplantation of donor beta-cells, allowing recipients to live their life free from daily insulin injections. While promising, the major challenge now lies in finding a source of replacement beta-cells to treat the millions with diabetes.
Our lab has recently discovered a way to reprogram cells to become a completely unrelated cell type without having to remove them from the body. This discovery may allow us to generate new, replacement beta-cells directly in people with diabetes and bypass the safety issues associated with other approaches currently being investigated.
The prevailing approach that many researchers are taking to help produce more donor beta-cells is to generate them from cultured stem cell. But many safety concerns still need to be addressed, including the tumor forming potential of these cultured cells and their rejection by the recipient’s immune system. Recognizing these concerns, researchers are exploring the use of encapsulation devices to prevent transplanted cells from leaking into the body. However, using devices to encapsulate cells raises new issues including device efficacy, durability and implantation site scarring.
Given the concerns associated with transplantation of cells cultured from stem cells, our lab sought a completely different approach to generate replacement beta-cells. Using our knowledge of how cell identity, particularly pancreas cells, is genetically programmed and our new theory of cell identity regulation, we recently devised a method to reprogram completely unrelated cells into cells that can normally go on to form beta-cells. With this breakthrough, we believe we have made a substantial advance towards converting nearly any cell type of our choice into replacement beta-cells, without having to remove them from a patient’s body.
Efforts to reprogram the identity of cells without removing them from the body (in vivo) have been restricted to converting cells that are already closely related to beta-cells. However, these cells come from tissue like the pancreas and liver that may already be stressed in diabetics, making their use potentially harmful to the patient. Instead of targeting these cells, our discovery suggests that it may be possible to directly generate replacement beta-cells from more abundant and nonessential cells, such as fat, skin, and muscle cells, and potentially from immune privileged tissues within a patient’s body. This approach would bypass the need for potentially harmful cultured cells, invasive surgeries, bulky encapsulation devices, and immunosuppressants.
To make in vivo cell lineage reprogramming practical and safe, we aim to expand the types of cells that can be converted into beta-cells. Our vision is to reprogram a small subset of cells directly into beta-cells from select, non vital tissues throughout the body without disrupting the normal functions of that tissue. We have now overcome a major limitation of in vivo cell lineage reprogramming by converting completely unrelated cells into cells that can go on to form beta- cells. It is now imperative that we continue to push and further guide our in vivo induced naïve cells into functional beta-cells. With your support, we will be able to accelerate our proof of concept studies to determine the feasibility of using in vivo cell lineage reprogramming to generate a vast new supply of replacement beta-cells.
Update on 9-30-17
Hello! It’s time again to give you all a quick update on our progress over the past month. As I mentioned in my last update, we were working hard to iron out some of the technical problems we were having as we attempted to isolate reprogrammed muscle cells that were changing their identity.
The reason we need to isolate these reprogrammed muscle cells is so we can carefully analyze and characterize how their identity change is occurring. Armed with that information, we can then determine what other changes we need to make in order to continue to push reprogrammed muscle cells into beta cells.
Below is a cartoon to remind you what we are trying to do:
A key part of our experiments that I think is important for you to understand is our need to also isolate and analyze control muscle cells. Control muscle cells are important because they do NOT undergo reprogramming and therefore tell us what mRNA normal muscle cells usually express. Knowing this, we can then compare the types of mRNA that normal muscle cells express to the mRNA that reprogrammed muscle cells express, allowing us to detect differences in mRNA expression between the two.
Over the past month we have repeated our experiments several times and tweaked several parameters in order to increase the number of reprogrammed and control muscle cells. This allowed us to isolate more reprogrammed or control muscle cells per experiment. Even though we were able to collect more cells, we still haven’t been able to collect enough cells to do really in depth analysis. However, we were able to isolate enough reprogrammed and control muscle cells to do important preliminary analysis.
In our preliminary analysis of the molecular changes in reprogrammed muscle cells, we could detect expression of mRNAs that are only expressed in early naive gut like cells! Importantly, we never detected these mRNA in control muscle cells! This means that our analysis will work and that reprogrammed muscle cells are in fact changing their identity and beginning to express mRNA that is important for formation of early naive gut like cells.
So, for the next month, we will continue to tweak our experimental conditions in order to get more reprogrammed muscle cells and control muscle cells. This will allow us to do more in depth and complete analysis of the molecular changes that are occurring during muscle cell reprogramming.
More cells! More analysis! Until next month……
Update on 8-31-17
The ultimate goal is to determine whether we can transform completely unrelated cells in the body into functional beta-cells by successfully reprogramming muscle or skin cells into a naive gut like cell that can go on to form tissue like the pancreas (where beta cells normally develop). We need to carefully analyze and characterize how this change is occurring so we can determine what other changes need to be made in order to continue pushing these reprogrammed muscle or skin cells into beta cells. Going forward, we will initially focus our efforts on reprogramming and analyzing muscle cells in order to thoroughly understand the molecular changes that occur while reprogrammed muscle cells change identity in vivo, this requires isolation of the reprogrammed muscle cells by separating them from muscle cells that have not been reprogrammed (see Diagram below).
Over the past month, we have made great progress in working out the proper conditions to efficiently deliver our conversion factors and the fluorescent tag to be sure that a muscle cell always receives both the factors and the fluorescent tag and still remains healthy. We also had to be sure that the fluorescent tag itself did not influence our reprogramming efforts (it does not). Although not fully optimized, we have had enough success to begin trial runs of cell sorting using FACS.
Over the next month, we will continue to optimize the delivery of the fluorescent tag and the cell sorting. During this time, the goal is to isolate enough reprogrammed muscle cells in order to begin in depth analysis of the molecular changes that are occurring. Armed with this information, we can begin making plans for how to try to keep pushing these cells closer to a functional beta cell!”
Update on 7-1-17
We have cleared a major hurdle in our efforts to convert completely unrelated cells in the body into beta-cell pre-cursors. We have discovered that delivering two factors into muscle or skin cells can convert them into a naive gut cell type that can go on to form tissue like the pancreas, where beta cells normally develop. In order to now try and continue to push these reprogrammed muscle or skin cells into beta cells, we need to thoroughly understand the molecular process that occurs while they change identity.
Over the next 3-4 months, I will be analyzing converted cells in order to determine the critical molecular changes that occur as they change their identity. These experiments will yield data necessary to inform our next strategy to drive these cells closer to becoming functional beta cells.
By successfully moving this project forward, we are exploring a fundamentally novel therapeutic approach for beta-cell replacement. It is also creating an opportunity to help those who deal with the complications of diabetes every day of their life. The experiments I am currently focused on should lead to new and exciting insights into changing cell identity in vivo and bring us a few steps closer to our goal of generating beta-cells in the body. And it is because of your generous support and the support of the DRC that it is possible.