About cell therapy
The process of using cells to treat a disease is called cell therapy. The first bone marrow transplant (i.e. the first transplant of blood stem cells) in Sweden took place in 1975. Since that time, research has discovered new types of cells and ways of culturing them, which has opened the door to the use of different types of cells. Cell therapy was formerly classified as a form of transplant. If the cells are cultured or significantly manipulated in other ways, or if they are intended for a function other than the original function, the cell therapy is now defined as a medical product. Examples of cell therapy include mesenchymal stem cells for treatment of graft-versus-host disease, keratinocytes for treatment of burn injuries, and cultured cartilage cells for treatment of arthritis. The use of cell therapies requires authorisation from the Swedish Medical Products Agency (marketing authorisation, clinical trials, or hospital exemption).
Cell therapy is regarded as an advanced therapy medicinal product, or ATMP. Working with an ATMP requires a risk-based approach, which varies widely depending on the cell therapy in question, the stage of development of the product, the patients who are to be treated, and so forth. The selection of donor is very important in order to minimise the risk of transferring diseases. Another risk is that the cells can form tumors. Mesenchymal stem cells have never formed tumors in patients, but careful examinations are required and treated patients require long-term follow-up.
Mesenchymal stem cells (MSC) are a special type of stem cells that are present in connective tissue (stroma). They have powerful immune regulating and healing characteristics, and have proven to have clinically beneficial effects on many different conditions, for example type 1 diabetes, vocal cord injuries, acute respiratory distress syndrome (ARDS) and graft-versus-host disease (a serious immune reaction that can occur when one person donates hematopoietic stem cells to another person in what is known as an allogenic hematopoietic stem cell transplant. MSC therapies are regulated by the EU as an ATMP, advanced therapeutic medicinal product.
T-cells/T-lymphocytes are very important actors in the immune response. They are part of the adaptive response which must be presented with different bacteria and viruses in order to enable it to then build up a defense. A memory is then created, which causes a much quicker response the next time since there are memory T-cells. T-cells are important in the response to cancer cells. Mutations are constantly occurring in the body although cancer is relatively uncommon – this is because the body has a good response to anything that is unknown or wrong. This can be applied as a pharmaceutical product. T-cells from seriously ill cancer patients can be harvested from a blood sample. When gene therapy is applied, these T-cells begin to express a particular type of receptor on the surface of the cell directed towards a particular type of cancer cell. These T-cells can then be stimulated in cultures to multiply several million-fold and, after 4 weeks, they are returned to the patient as an aggressive form of cancer treatment. These modified cells are called CAR-T-cells, which refers to the particular receptor which is formed on the surfaces of the cells – a chimeric antigen receptor. Intensive research is underway worldwide to enable the creation of CAR-T-cells that are effective against different types of cancer, to reduce the side effects, and to be able to create CAR-T-cells from an unrelated donor, since the patients are often so seriously ill that waiting several weeks for treatment could lead to a critical situation.
Exosomes are small vesicles/blisters which bud from different types of cells. Research has shown that exosomes from mesenchymal stem cells can have similar effects to treatment with the actual stem cell, which is beneficial since exosomes are more comparable to “ordinary” medicines in terms of dosage, storage, and administration.