The first are nestled in an embryo a few days

The time of science and medicine time walk rarely the same pitch. It is even more true for stem cells, a subject which raises an unqualified enthusiasm among biologists and extreme caution among therapists. For the first, it is an enormous challenge: elucidate the functioning of living capable of producing a complete organization from a single cell. Through a cascade of differentiation, this vital egg gives rise to 250 types of specialized cells constituting bodies. In addition, the Organization has a self-healing capacity that varies depending on the species.

For physicians, the "cell drug" and regenerative medicine remain distant concepts. The old adage "primum non nocere" (first, do no harm) makes perfect sense to the many unknowns related to cellular therapies. "For the moment, there is no significant progress", was recently Philippe Ménasché, a cardiac surgeon at the European hospital Georges-Pompidou before the parliamentary Office for evaluation of scientific and technological choices (Opecst). "This is an area which will explode in the next decade." "It will get there," judge Olivier Pourquié, Director of the Institute of genetics and molecular and cellular biology (IGBMC) of Illkirch, making the discipline a priority axis.

The organization produces cells permanently to offset losses due to external aggression or wear. A red blood cell has a shelf life of one hundred and twenty days, the skin cells are renewed every 30 days and those of the intestinal epithelium live between three and five days. We must therefore renew permanently those millions of brave soldiers who disappear every day. "Cell death is a natural phenomenon." "In a life, a human body produces dead cells body weight", says Nicole Le Douarin, Professor at the College of France.

How to set in motion the process of renewal Why an amputated human limb only pushes not in the same Why do some animals, such as the salamander, have this ability Where hide the workshop leaders who control this production These issues back biologists from around the world and weigh tens of Nobel Prize. Signs of time, the pharmacy industry begin to look closely at these breakthroughs. "There is in Sanofi and rock of the clearly identified divisions in regenerative medicine," said Philippe Menasché.

The past year, the Swiss Roche signed an agreement with the PMI of Evry I-Stem. Objective: new solutions for the next plague of aging societies: neurodegenerative diseases. The cancer also rely on this work to decipher a poorly understood phenomenon: carcinogenesis. "What are cells that are at the origin of a tumour and what type of therapeutic innovation can we expect that knowledge" asked Daniel Louvard, Director of the centre for research of the Curie Institute in Paris.

Three types of cells

Three main types of pluripotent cells, able to produce specialized cells now known. The first are nestled in an embryo a few days. The use of these (HESC) human embryonic stem cells is the subject of many controversies. Fortunately, it was discovered adult cells have also the power to trigger the production of spare parts. These (CSA) adult stem cells are embedded in the bodies. Found in the bone marrow, shaping all the components of the blood (CSH). Product brain he also thousands of néoneurones per day. The epidermis is similarly to renew skin or heal wounds. "We have identified in the epidermis five types of cells that have the potential to generate 25 different lineages." It's as if he were still in our adult skin stem cells. "It is quite fascinating," says Michèle Martin, a specialist in this field (kératinopoïese) at the CEA.

A third way itself revolutionary was discovered recently by a team of Japanese researchers: pluripotent stem cells induced (iPS). Through a reprogramming in vitro very delicate and at the moment very random, these iPS differ in most tissues of the body. This family, which throws all ethical obstacles because it avoids using embryonic stem cells, is the subject of many works. "He needed front research on embryonic cells and iPS", stresses Olivier Pourquié.

Tests in vitro

In Western countries, work on stem cells are very supervised. But the hopes they generate have given rise to alarming new: cell tourism. "Sick in a desperate situation to leave trap by the myth of injections of cells." "These abuses are difficult to control, but they are the result of too restrictive laws," notes Philippe Menasché.

Until the advent of all these therapeutic advances, the first outlet of stem cells will be more modest. Have stable cardiac nerve, liver cell lines, and reproducing at infinity is a wonderful opportunity to test in vitro efficacy or safety of the chemical molecules or new drugs. The British, very in-the-art in this area, have announced the color. The first outlet of stem cells is located in the chemical industry, under the European programme Reach, which is the measure of the toxicity of chemicals. A way to hand before the great boom of regenerative medicine that everyone expects.

Find the interview with Jean Leonetti, physician and specialist in bioethics on