In the Sancho Lab, we are fascinated by the fundamentals of how the cells in the pancreas become what they are and how we can harness this information to direct their fate to cell types we want. We hope to apply this information into developing new therapies for treating different types of diabetes. We are currently focussed on two types of diabetes: type 1 diabetes (T1D) which affects around 10% of people with diabetes and around 8.4 million individuals globally and mature onset diabetes of the young (MODY) which is much rarer, only affecting 1-2% of people with diabetes. We are also interested in other mutations that affect insulin production, such as those found in people with Hyperinsulinism. In these patients, the problem is the opposite of diabetes, as they produce more insulin that they should.
Our Research Interests
Diabetes and Islets
Diabetes mellitus are a group of conditions in which your body does not properly regulate the level of the sugar called glucose in your blood. In the short term this leads to symptoms such as a lack of energy, weight loss, frequent urination, and dehydration. Poor control of blood glucose levels can also lead to serious long term complications including vision loss, kidney problems, and nerve damage.
The architecture of a pancreatic islet. Credit: Vecteezy
Like T1D, patient’s with MODY have reduced production of insulin leading to poor regulation of blood glucose. But unlike T1D, which is caused by a complex mix of genetic and environmental factors, MODY is caused by a single gene mutation. The most common gene mutations, found in 70% of cases, are in the gene HNF1A which makes the protein hepatocyte nuclear factor-1 alpha (HNF-1a). HNF1-a can bind to DNA and turn genes “on” and “off”. When a gene is turned on it is turned into a protein. HNF1A’s role in this is crucial for the development and growth of β cells and therefore insulin production, although it is not entirely clear how it does this.
T1D is an autoimmune disorder caused by the patient’s immune system destroying β (beta) cells in the pancreas. β cells produce the hormone insulin, which is required to control your blood glucose levels. In T1D, their loss means not enough insulin is produced and blood glucose is not adequately controlled. β cells are found in clusters of hormone producing cells in the pancreas called islets of Langerhans. Several types of cells are found in islets including:
What We Do
T1D can be well managed through the daily administration of insulin, via injections or an insulin pump, however this is not a cure and does not work well for everyone. One of the things we are investigating is how to convert other pancreas cells into β cells for potential future therapies to replace destroyed beta cells in T1D.
To study this, we have developed pancreatic organoids – a miniature, simplified version of the pancreas that can be grown in a dish. Unlike normal cells in a dish, which lay flat on a surface, organoids are 3 dimensional which means they can have some of the same architecture of the organ, although they are not exactly the same.
There are a few key terms to know here:
Stem cell: a cell with the ability to self-renew and specialise (differentiate) into other cell types.
Adult pancreatic stem cell: stem cells from the pancreas that will give rise to cells in the pancreas only. Their existence in a matter of debate
Induced pluripotent stem cell (iPSC): adult skin or blood cells which have been converted back into stem cells. The benefit of iPSCs is that they provide a potentially unlimited source of cells for research. We can produce them from patients and use them to study specific mutations and how they affect the normal function of beta cells.
We make pancreatic organoids from both adult pancreatic stem cells and induced pluripotent stem cells. The use of pancreatic organoids allows us to explore these crucial questions: what is needed for the cells to differentiate into β cells? How do cells communicate with each other and with their surroundings? What changes happen during disease?
Early pancreatic organoid made from iPSCs. Red and blue show pancreas proteins and blue shows the nucleus of the cells. Credit: Ana-Maria Cujba
For example, in one of our projects we used iPSCs from patients with MODY or which have been genetically modified to have a mutation in HNF1A to generate early pancreas cells which we then culture to make pancreatic organoids. This allowed us to study what goes wrong in the pancreas in patients with MODY in a dish.
As mentioned above, one key avenue of research in our lab focusses on understanding how the cells in the pancreas develop. During the development of the pancreas, there are a number of genes which must be turned on to allow early pancreas cells to become the different cell types in the islet. The role of these genes is well established in determining a cells’ fate, but very little is understood about how they are modified after they become proteins, which can affect how they function and how long they function. For example, when a protein is no longer needed, it can be modified to be destroyed by the cell. We are exploring how this kind of modification affects the proteins needed for producing β cells, with the idea that we could harness the mechanisms that control protein destruction and boost the production of more β cells in a dish.
Growing β Cells
Another factor that affects beta cell production are the physical properties around them, which of course are difficult to reproduce in a dish even when those cells are grown in 3D. Therefore, we are also exploring different gels to culture organoids in which could help them grow and differentiate into β cells more efficiently.
β cells grown in a dish can be transplanted into patient’s with T1D to replace those destroyed, therefore all the improvements in the differentiation protocols to produce more numbers and more functional beta cells would result in a great advancement in the field.
Image: Insulin (Green); Somatostatin (Red) and cell nucleus (blue) in iPSCs differentiated to β cells when NGN3 degradation is inhibited. Credit: Teodora Manea
Single Cell RNA-sequencing
We have already discussed how we use pancreatic organoids to explore our questions. Another of the tools we commonly employ to understand cells is called single cell RNA sequencing (scRNA-seq).
Most of your cells contain exactly the same genome, which is “written” in your DNA. The specialised structure and function of cells is determined by which combinations of genes in your DNA are turned ON (expressed) and OFF (supressed) at different times.
The Central Dogma of molecular biology. "DNA makes RNA, and RNA makes protein". Credit: Khan Academy
Ribonucleic acid or RNA is structurally similar to DNA, made up of sequences of small molecules called nucleotide bases (ACGU) which make up your genetic code. Unlike DNA it is just a single strand of bases. RNA acts as the “messenger” carrying instructions from DNA to be made into protein. Determining the sequence of the bases in RNA, which can be done by RNA-Seq, can tell us what genes are being expressed and how much they are being expressed in a group of cells. You can use this to see how gene expression differs between different tissues (liver vs pancreas) or between healthy and unhealthy individuals (healthy vs MODY).
scRNA-Seq carries this out in more detail, determining the individual RNA sequence in hundreds or thousands of individual cells. This is particularly helpful in pancreatic islets which have many cell types. By using scRNAseq in our organoids we can see the difference in the expression of β cell genes in cells after different differentiation protocols, when changing the physical properties of the gels the organoids are grown in, or when we use organoids from patient cells vs organoids form mouse cells. All of this allows us to find new ways to generate β cells more efficiently.