What is Regenerative Medicine?
Regenerative medicine is the branch of scientific research that is focused on generating cells, tissues or organs with the purpose of implanting them in humans with the aim of treating disease or replacing a damaged organ.
What Are Stem Cells?
Most cells in the body are specialised and make up either a solid organ (eg. liver cells and kidney cells) or a non-solid organ such as blood. In contrast, stem cells are cells that can divide to make more stem cells (a property called ‘self-renewal’), while also giving rise to multiple, or all, types of cells in the human body including specialised cells found in organs and tissues. There are two main types of stem cells: embryonic and adult stem cells. In addition, adult cells can also be made into ‘induced pluripotent stem cells’ (iPSCs).
Embryonic Stem Cells
These types of stem cells are found in the very early stages of the embryo and have the capacity to become any of the 200+ types of cells in the body. These cells have the ability to constantly divide and continuously produce the same kind of un-specialised cells. However, depending on their cellular environment and chemical signals they receive, they can switch to become more specialised or ‘differentiated’ cells. In general, most embryonic stem cells have specialised by week 5 of the embryo development and are therefore not found in adults. Embryonic stem cells have great potential for regenerative medicine since they could theoretically be used to derive any organ that might be needed at the appropriate time. They can, however, only be obtained from embryos which raises important ethical and moral issues.
Adult Stem Cells
These types of stem cells are found in babies, children, and adults and usually have the capacity to develop into one type of cell or a group of closely related cells. They are found at the location of the organ they develop into and essentially serve as a repair or maintenance mechanism for the tissue in which they are found. Blood forming stem cells, found in the bone marrow, are an example of adult stem cells that are routinely used for the treatment of blood diseases such as leukaemias. Adult stem cells are increasingly identified and can be even more beneficial than embryonic stem cells as they are closer to the desired cell type for the potential therapeutic approach, as well as having fewer ethical issues related to how they are obtained.
Induced Pluripotent Stem Cells
Induced Pluripotent Stem Cells (iPSCs) can be made from adult specialised cells, whereby laboratory techniques are used to turn them ‘back’ into stem cells. The word ‘pluripotent’ signifies their ability to subsequently become many other types of specialised cells such as insulin-producing cells. Many cell types, including skin cells and blood cells can be made into induced pluripotent stem cells. A lot of research is going into optimising the best methods for turning these induced pluripotent stem cells into functional specialised cells, including insulin-producing cells. This approach offers the exciting potential that at some point in the future, skin or other cells form a patient can be turned into ‘their own’ specialised cells to treat their disease.
Regenerative Cellular Therapies for Type 1 Diabetes
Cell therapy involves using living cells, usually derived from stem cells, to treat a disease or condition. For the treatment of T1D, the aim is to produce insulin-producing cells from adult stem cells, from induced pluripotent stem cells, or by changing one specialised cell type into another specialised cells type, in this case insulin-producing cells. This last method is called ‘trans-differentiation’. They present an exciting opportunity whereby an unlimited supply of β-cells can be generated for transplantation into patients with diabetes, thus resulting in long-term treatment or permanent cure of diabetes in that patient. In principle, the original cells that are used to generate the insulin-producing cells can be obtained from the patient with diabetes or from a donor. If the cells originally come from a different individual, the immune system will recognise these cells as foreign and will attack them, unless the immune response is reduced using immunosuppressive drugs.