Name: reprogramming mature cells into stem cells
Uploaded: 2019-03-11T09:21:22.000Z
Duration: 1 min 13 s
Channel: JoVE

- [Formateur] Les cellules souches pluripotentes induites,ou CSPi,sont des cellules matures et différenciées,comme les cellules cutanées,qui ont été reprogrammées en laboratoire pour ressemblerà des cellules souches embryonnaires indifférenciées,c'est-à-dire qu'elles se divisent et sont pluripotentes,capables de reproduire tout type de cellules du corps,par exemple, des cellules rétiniennes pouvant servirà remplacer le tissu rétinien endommagé. 
Pour créer des CSPi, des cellules matures,comme des fibroblastes de la peau,sont prélevées sur le patient et mises en culture. 
Puis, généralement, les gènes des facteurs de transcriptionsont acheminés, grâce à des vecteurs viraux,aux noyaux cellulairesoù ils sont incorporés au génome. 
Puis les facteurs de transcription activent les gènesexprimés par les cellules souches embryonnairesprovoquant leur dédifférenciationet leur transfert vers un état pluripotent. 
Les cellules peuvent, à présent, se diviseret, dans l'idéal, être orientéesvers la production en culture d'un certain type de cellules. 
Ces nouvelles cellules peuvent alors être transplantéessur le patient pour traiter des lésions ou des pathologiesavec un risque minimal de rejetpuisqu'elles proviennent des cellules du patient.

Hamazaki, Takashi, Nihal El Rouby, Natalie C. Fredette, Katherine E. Santostefano et Naohiro Terada. « Revue concise : recherche sur les cellules souches pluripotentes induites à l’ère de la médecine de précision », Cellules souches (Dayton, Ohio) 35, n° 3 (mars 2017) : 545-50. [<a href="https://doi.org/10.1002/stem.2570 » target="__blank">Source</a>].

cellules souches pluripotentes induites

Induced Pluripotent Stem Cells

Les cellules souches sont des cellules indifférenciées qui se divisent et produisent différents types de cellules. Habituellement, les cellules qui se sont différenciées en un type précis de cellule sont post-mitotiques, c’est-à-dire qu’elles ne se divisent plus. Cependant, les scientifiques ont trouvé un moyen de reprogrammer ces cellules matures afin qu’elles “ se dé-différencient ” et reviennent à un état prolifératif non spécialisé. Ces cellules sont également pluripotentes comme les cellules souches embryonnaires — capables de produire tous les types de cellules — et elles sont donc appelées cellules souches pluripotentes induites (iPSC).
 
 Les iPSC sont potentiellement utiles en médecine car un patient ayant besoin d’un type de cellule particulier, comme par exemple une personne ayant une rétine endommagée à cause de la dégénérescence maculaire, pourrait recevoir une greffe des cellules requises, générées à partir d’un autre type de cellule dans son propre corps. C’est ce qu’on appelle la transplantation autologue, et elle réduit le risque de rejet de la greffe qui peut se produire lorsque les tissus sont transplantés entre les individus.
 
 <h4>Le procédé</h4>
 
 Pour créer des iPSC, les cellules matures telles que les fibroblastes de la peau ou les cellules sanguines d’une personne sont mises en culture. Ensuite, les gènes de plusieurs facteurs de transcription sont livrés dans les cellules à l’aide d’un vecteur viral, et les protéines des facteurs de transcription sont exprimées à l’aide de la machinerie de la cellule. Les facteurs de transcription activent alors plusieurs autres gènes qui sont exprimés par les cellules souches embryonnaires, renvoyant les cellules à un état indifférencié, prolifératif et pluripotent. 
 
 On étudie encore si les iPSC sont vraiment équivalentes aux cellules souches embryonnaires, mais elles semblent être similaires et peuvent produire des cellules des trois couches germinales du corps. Comme pour d’autres types de cellules souches, les scientifiques apprennent à promouvoir efficacement la différenciation de types de cellules spécifiques à partir des iPSC, de sorte que les types de cellules nécessaires puissent être produits en quantités suffisantes. 
 
 <h4>Les essais cliniques précoces</h4> 
 
 Le premier essai clinique a transplanté des cellules rétiniennes dérivées des iPSC dans des patients présentant une dégénérescence maculaire liée à l’âge. Depuis, plusieurs essais cliniques d’iPSC ont été approuvés pour le traitement de la maladie de Parkinson, de maladies cardiaques et de lésions de la moelle spinale. Les cellules prélevées sur les patients et transformées en iPSC sont également utilisées pour étudier leurs maladies en laboratoire. En général, les iPSC fournissent une autre source de cellules souches pour la recherche scientifique.

Cellules souches pluripotentes induites

Les cellules souches sont des cellules indifférenciées qui se divisent et produisent différents types de cellules. Habituellement, les cellules qui se sont différenciées en une cellule spécifique ...

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reprogramming mature cells into stem cells

Reprogramming mature cells into stem cells lets scientists turn specialized cells back into an unspecialized state. These cells are called induced pluripotent stem cells, or iPSCs. Like embryonic stem cells, iPSCs are pluripotent, which means they can form all cell types.

To make iPSCs, researchers start with mature cells such as skin fibroblasts or blood cells. The cells are grown in culture, and genes for several transcription factors are delivered with a viral vector. The cells then make those transcription factor proteins, which switch on other genes that are active in embryonic stem cells and return the cells to a proliferative, undifferentiated, and pluripotent state.

iPSCs may be useful in medicine because they can come from a patient’s own body. For example, cells needed to repair a damaged retina in age-related macular degeneration could be made from that same patient’s cells. This autologous transplantation lowers the risk of transplant rejection that can happen when tissue is moved between different people.

Scientists are still studying whether iPSCs are truly equivalent to embryonic stem cells, but they appear to be similar and can produce cells from all three germ layers. Researchers are also working on ways to direct iPSCs to become specific cell types in efficient amounts. Early clinical trials have used iPSC-derived retinal cells for macular degeneration, and other trials have been approved for Parkinson’s disease, heart disease, and spinal cord injury. Patient cells turned into iPSCs are also helping scientists study disease in the lab.

Reprogramming Mature Cells into Stem Cells

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what is genetic engineering?

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induced pluripotent stem cells

Reprogramming mature cells into stem cells lets scientists turn specialized cells back into an unspecialized state. These cells are called induced pluripotent stem cells, or iPSCs. Like embryonic stem cells, iPSCs are pluripotent, which means they can form all cell types. To make iPSCs, researchers start with mature cells such as skin fibroblasts or blood cells. The cells are grown in culture, and genes for several transcription factors are delivered with a viral vector. The cells then make...

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genomics

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key terms and concepts

Learn how mature cells are reprogrammed into induced pluripotent stem cells, why iPSCs matter for transplants, and how they are used in research and clinical trials.

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Reprogramming Mature Cells into Stem Cells

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