Objective
Our research proposal aims to investigate how a group of adult stem cells, known as mesenchymal stem/stromal cells (MSCs), located in the pancreas may be involved in helping to protect people from developing type 1 diabetes (T1D). We will investigate what goes wrong in T1D, and how these native pancreas MSCs may be altered in terms of their number, location and function. The scientific knowledge generated will inform how best to use MSC-based intervention therapies to delay, or even prevent T1D.
We hypothesise that native pancreas MSCs help protect the pancreatic insulin secreting islet beta cells from destruction by harmful immune cells. We will use state-of-the art microscope and imaging techniques to visualise native pancreas MSCs and investigate their alterations in T1D. We will use pancreas samples from children with recent-onset T1D that have been preserved by chemical “fixation”, which will enable us to address our scientific questions using the most appropriate methodology available worldwide. Specifically, these pancreas samples enable us to study the pancreas tissue, and the processes that lead to the destruction of insulin-secreting islet beta cells. We will use these samples to investigate whether native pancreas MSCs play a role in preventing the immune processes that leads to the destruction of beta cells and the subsequent development of T1D. We will determine whether the MSCs interact with the immune cells responsible for destroying the beta cells. We will also determine whether MSCs play a role in maintaining the “peri-islet basement membrane”. This is a protective capsule/matrix surrounding the islets which prevents harmful immune cells from physically getting to the islet beta cells to destroy them. We know that this protective capsule is lost during the development of diabetes and that MSCs can produce many of the components of this capsule (as seen in experimental settings outside of the pancreas). We will use histology techniques to identify these capsule components and whether the capsule is more complete where we find MSCs in the pancreas of individuals with and without T1D.
This will involve histology techniques that use antibodies tagged with a fluorescent protein, which can be different colours to label multiple cell types and proteins of interest. Using appropriate antibodies, we will label the cells of interest in the pancreas/islets (e.g native pancreas MSCs, islet capsule components, islet beta cells and immune cells) with the fluorescent tag to help determine the role of native pancreas MSCs in health and in the development of T1D. We have state-of-the art microscopes and imaging facilities that will allow us to study multiple cell types at the same time using different coloured antibodies. This means that we can investigate the interaction of native MSCs in the pancreas with islet cells and the immune cells that destroy the beta cells leading to the subsequent development of diabetes. We will investigate whether native pancreas MSCs play a role in protecting the islet beta cells from immune attack and whether their role in preserving beta cell function and survival varies between specific subgroups of individuals with T1D. These studies will provide detailed information upon the specific subsets of individuals who are most likely to benefit from MSC-based therapeutic intervention strategies, the most appropriate timing of MSC intervention and the mechanisms through which MSCs help to prevent diabetes.
Background Rationale
We have begun to understand a lot about the function of exogenous MSCs that have been isolated from different tissue sources, including bone marrow, fat tissue and the pancreas. However, we know very little about endogenous/native MSCs that are found naturally in the human pancreas tissue. We aim to determine whether the number, distribution and function of native pancreas MSCs is altered in T1D. We will determine whether native pancreas MSCs have a role in health to protect pancreatic islets from immune attack and destruction. Accordingly, our preliminary data have shown that MSCs surround the islets in the pancreas samples from an individual without diabetes. Our fluorescent microscope images show that the native pancreas MSCs are essentially forming a protective barrier around these healthy islets, in which the islet beta cells have lots of insulin. In contrast, in an individual who has T1D, we see far fewer MSCs around the islets in the pancreas and no insulin secreting beta cells are left. Thus, in the proposed study, we will investigate the pancreas tissue of more individuals with and without diabetes to gain a deeper understanding of native pancreas MSCs. We will establish whether the normal function of native pancreas MSCs is altered in T1D. This knowledge will help us to define a likely protective role for native pancreas MSCs and inform MSC-based strategies to intervene in the development of T1D.
We are fortunate at the University of Exeter to host the Exeter Archival Diabetes Biobank (EADB) a historical autopsy biobank containing the world’s largest single collection of pancreas samples from children with recent-onset T1D. Very few pancreas samples of this nature are available worldwide, thus offering a unique opportunity to perform the proposed studies, which are crucial to better understanding the function(s) of native pancreas MSCs and what goes wrong in diabetes. This rare and extremely valuable recourse enables us to investigate the role of endogenous/native pancreas MSCs in T1D development because the islet inflammation and immune attack is still ongoing in these pancreas samples. MSCs are complex cells that require multiple antibodies (each tagged with a different fluorescent protein of different colour (6-8)) to identify them in the human pancreas. Therefore, the histological methodology required to perform the studies in this proposal requires state-of-the art histology techniques, microscopes and imaging facilities. We are uniquely placed in terms of equipment (state-of-the art imaging and analysis technologies), resources (rare human pancreas tissue samples from individuals with T1D and without T1D for comparison) and expertise of the research team to address the outlined studies.
These investigations will be crucial to enhance our understanding of native pancreas MSCs and their role(s) in protecting individuals from developing diabetes. The studies will help to determine whether MSC-based interventions are likely to achieve greater success in the quest to slow disease progression in defined T1D patient subgroups. Studies of different pancreas samples at different stages of diabetes progression will help to inform the most appropriate timing of MSC intervention and the mechanisms through which MSCs help to prevent diabetes.
Description of Project
Our research proposal aims to investigate how a group of adult stem cells, known as mesenchymal stem /stromal cells (MSCs), located in the pancreas may be involved in helping to protect people from developing type 1 diabetes (T1D). MSCs are found in most parts (tissues) of the body, including the pancreas, bone marrow, fat tissue and kidney. When samples of these tissues are taken, MSCs can be isolated in the lab and when fed with appropriate nutrients will expand in number, so that we have enough MSCs that may be used therapeutically to treat inflammatory and autoimmune conditions. Once isolated and expanded in this way we refer to these cells as exogenous MSCs, as opposed to endogenous/native MSCs that are found naturally in the tissue from which they were isolated.
Researchers in the diabetes field often refer to these exogenous MSCs as ‘Islet Helper’ cells. This is because experimental studies have shown that exogenous MSCs improve the ability of islet beta cells to produce insulin in response to increased sugar levels. Additionally, experimental studies have shown that exogenous MSCs can help to protect islet beta cells from immune attack and destruction. Thus, exogenous MSCs target harmful immune cells to prevent them from destroying the insulin producing beta cells. Exogenous MSCs can also help the good (regulatory) immune cells to protect islet beta cells from the bad immune cells. Clinical trials have shown that that MSCs isolated from the bone marrow and expanded in the lab (exogenous bone marrow MSCs) help to preserve the function of the insulin producing pancreatic islet beta cells in some individuals with newly diagnosed T1D, after infusion into the blood circulation.
Whilst we have established a lot about the function of exogenous MSCs from multiple different tissues, our understanding of endogenous/native MSCs located in the pancreas, with regards to their role in health and T1D is limited. We aim to determine whether the number, distribution and function of native pancreas MSCs is altered in T1D. We will determine whether native pancreas MSCs have a role in health to protect pancreatic islets from immune attack and destruction. We will establish whether the normal function of native pancreas MSCs is altered in T1D. These studies will provide scientific information on MSC-related changes in T1D, that we can target therapeutically to help delay or prevent the progression of diabetes. We will further establish whether there are differences in native pancreas MSC number, distribution and function in different subgroups of individuals with T1D, thus determining which subgroups are most likely to benefit from MSC-based therapeutic intervention. Our detailed studies will further help to determine the most appropriate timing during T1D progression for MSC-based therapeutic intervention, thus increasing the likelihood of success in the quest to slow disease progression in defined T1D patient subgroups.
Anticipated Outcome
We anticipate that the outlined studies will help us to understand more about the role of native human pancreas MSCs in maintaining normal pancreatic islet beta cell function and survival in health, and in helping to protect the insulin-producing islet beta cells from immune attack during the development of T1D. Our investigations are likely to reveal defects in immunosuppressive and islet-protective function(s) of MSCs during T1D progression. As well as generating novel scientific data regarding the number and location of native pancreas MSCs we expect to discover far more about the immune cell types in the pancreas that the MSCs are interacting with during health and T1D progression. This is likely to reveal novel mechanisms through which native MSCs may protect individuals from developing T1D and will provide critical insight into MSC-based therapeutic intervention strategies.
Our unique human pancreas samples and novel approach will help us to determine whether alterations in native pancreas MSCs are more pronounced in certain T1D patient subgroups. By understanding more about the role of native pancreas MSCs in health and T1D, we anticipate that our findings will help to define how MSC-based clinical intervention strategies may be best used to delay or prevent T1D progression. Our detailed histological studies of the human pancreas will further inform whether specific T1D patient subgroups are likely to respond better to MSC-based strategies for clinical intervention. Our studies are also likely to inform the most appropriate timing for MSC-based intervention strategies.
We expect to identify therapeutic immunosuppressive and regenerative agents that native pancreas MSCs produce to help protect islets from immune attack. If so, it may well be that the defined immunosuppressive factors produced by MSCs, could be used instead of the MSCs themselves, to intervene with the development of T1D. This will depend upon the mechanisms through which the defined immunosuppressive factors function. The scientific data generated from this project will help to define how best MSCs and/or their therapeutic factors can be used alongside pre-existing intervention strategies to maximise the time in which we can clinically delay T1D onset, or even prevent T1D.
Relevance to T1D
Approximately 10 percent of people living with diabetes have Type 1 Diabetes (T1D). Strategies that help to delay or prevent T1D have potential to help many individuals from developing T1D.
Mesenchymal Stem/Stromal Cells (MSCs) have significant potential to reduce the destruction of insulin-secreting beta cells, during the development of T1D, due to a vast array of immunosuppressive and regenerative functions. The proposed project aims to define the role of native human pancreas MSCs in health and in T1D development and progression. We hypothesise that native pancreas MSCs help to protect the pancreatic insulin secreting islet beta cells from destruction by harmful immune cells. Understanding the normal role of native pancreas MSCs in health and what goes wrong in T1D development will help us to understand how we can used MSC-based therapeutic strategies to intervene in the development and progression of T1D. This project will also enhance our understanding of the T1D patient subgroups most likely to benefit from MSC-based intervention therapies.
Maintaining endogenous pancreatic islet beta cell survival will improve quality of life for many people who would otherwise develop T1D, by avoiding the short-term risks of hypoglycaemia that are associated with intensive insulin therapy. In the longer-term, maintaining endogenous beta cell function and survival reduces the risks of complications that arise from high blood sugar levels. These include damage to blood vessels that can have harmful effects on the function of many organs in the body including the kidneys and eyes.