Self-Renewal of Specialized Cells

Is the indefinite expansion of adult cells possible without recourse to stem cell intermediates?

The team led by Michael Sieweke at the Centre d'immunologie de Marseille Luminy (Université Aix-Marseille 2 / CNRS / INSERM) has shown that this is the case by achieving the ex vivo regeneration of macrophages, specialized cells in the immune system, over several months.

Published in Science on November 6, 2009, this discovery could be applied to other cell types. This research enables a clearer understanding of the mechanisms underlying cell differentiation, but above all raises many hopes for potential therapeutic applications.

The regenerative medicine of the future will be based on replacing damaged cells and repairing deficient organs, notably through the use of stem cells. Indeed, these cells are able not only to proliferate indefinitely but, in theory, to supply all types of cells to the human body.

However, the processes that allow the passage from adult (rather than embryonic) cells to stem cells ("reprogramming") are complex and full of risk, as are the processes necessary for the "retransformation" of stem cells into adult cells. The question then arises: might it not be more simple to generate the cells required without passing through the stem cell stage?

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