[LUM#6] The repaired body

[LUM Magazine] - Published on August 22, 2017 in Science-Society

Replacing damaged or diseased cells with healthy ones... That is the principle behind cell therapy. It represents the hope, at last, of a complete cure: the new frontier of^21st-century medicine.

There has been surgery. And medication. A new frontier in medicine has been emerging over the past few decades: cells. The principle of cell therapy is to implant healthy cells into a patient to replace damaged tissue. Its applications? Potentially infinite. Cancer, neurodegenerative diseases, cell-destroying conditions such as diabetes, heart attacks, osteoarthritis... "Thanks to cells, we can imagine completely curing diseases that are incurable by other means," explains John De Vos, head of the cell therapy unit at Montpellier University Hospital and researcher at the Institute for Regenerative Medicine and Biotherapy.

Some cell therapies are already well established and used on a daily basis. Their preferred tool? Adult stem cells, which are found in our organs and are specialized, capable of producing the different types of cells of the organ to which they belong. They are therefore responsible for repairing and renewing our tissues throughout our lives. For example, skin stem cells, which are harvested and then cultured, can produce up to a thousand times more epidermal surface area... Enough to treat severe burn victims with their own skin, without the risk of rejection.

Transplanting a new immune system

For decades, one of the most well-understood cell therapies has been based on blood stem cells, which produce blood cells. Known as hematopoietic stem cells (HSCs), they play a fundamental role in treating blood cancers. Injecting a sufficient quantity into a patient is equivalent to transplanting a new immune system... This has a dual effect: the transplant recognizes and destroys the cancer. And it replaces the original immune system, which has been damaged by treatment.

But where can these precious blood-producing cells be obtained? Either from the bone marrow of compatible donors: anonymous donations from international registries or family members. Or from placental blood. To do this, blood is collected from the umbilical cord of newborns whose parents have given their consent. Each frozen graft is added to a placental blood bank and then recorded in internationally coordinated registries... This allows patients around the world to obtain the compatible graft that could save their lives. "There are people in Turkey, Holland, the United States, and Germany who are living with the blood of a child born in Montpellier. The Montpellier UTC placental blood bank at Montpellier University currently has 2,500 units of placental blood," explains John De Vos.

HSCs can also be injected into the patient themselves, in an autologous transplant. Before particularly intense chemotherapy, HSCs are collected from a patient with lymph node cancer. After treatment, they are re-injected into the patient, allowing them to regenerate their immune system.

Spectacular healings

Another cell therapy has proven highly effective: treating diabetes with specialized pancreatic cells. These cells produce insulin, which regulates blood sugar levels."Some patients with very severe and unstable diabetes that has lasted for decades can thus stop insulin injections completely, at least for a while," explains John De Vos. This powerful treatment is only part of the solution to this disease. In particular, it cannot be generalized, as it would require far too many deceased donors.

Skin culture, treatment of blood cancers or severe diabetes... these cell therapies are already well established. But what about the therapies of the future? Immunotherapy, which is currently undergoing rapid development, involves treating patients with certain blood cancers by removing cells that are crucial for immunity: lymphocytes. These cells are genetically modified to teach them to recognize cancer... before being re-injected into the patient. Clinical trials have shown spectacular recoveries in children with acute leukemia that is resistant to all other treatments. " In cohorts where 100% of patients appeared to be doomed, the majority of patients were saved. It's very rare to see such a breakthrough in the treatment of a disease," enthuses John De Vos.

Regenerate any tissue

The revolutionary horizon of cell therapy ultimately also includes the famous pluripotent stem cells (Demain guérir LUM No. 2). Immature and unspecialized, they are capable of producing any type of cell in the body. They are found naturally in embryos around one week old, measuring one tenth of a millimeter... And in recent years, research has taught us how to obtain them by reprogramming mature adult cells. The next step is to induce them to specialize before injecting them. And then to watch them potentially regenerate any tissue or organ in the body (Induced pluripotent stem cells: a new paradigm for the study of human tissues, in Biologie aujourd'hui, 2016).

This research still requires years of development. The biggest question for now remains that of injection. "The injection technique has not yet been mastered; the injected cells do not necessarily find their place in solid tissue," explains John De Vos. Each organ has its own injection issues: for example, how can we ensure that neurons intended to treat Parkinson's disease project their axons to the right place? Stem cell research, which is extremely promising, will advance and undoubtedly find solutions on an organ-by-organ basis."

Keywords: LUM#6, LUM Magazine, Medicine, Research, Health, Science, Company