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 Moyens de livrer le médicament.

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Date d'inscription : 23/02/2005

MessageSujet: Une nouvelle technique pour livrer le médicament.   Ven 26 Juin 2009 - 13:24

(June 26, 2009) — It is now possible to engineer tiny containers the size of a virus to deliver drugs and other materials with almost 100 percent efficiency to targeted cells in the bloodstream.

C'est maintenant possible de faire des contenants de médicaments de la taille d'un virusqui ciblent les cellules cancéreuses avec 100% d'efficacité.

According to a new Cornell study, the technique could one day be used to deliver vaccines, drugs or genetic material to treat cancer and blood and immunological disorders. The research is published in the journal Gene Therapy.

"This study greatly extends the range of therapies," said Michael King, Cornell associate professor of biomedical engineering, who co-authored the study with lead author Zhong Huang, a former Cornell research associate who is now an assistant professor at the Shenzhen University School of Medicine in China. "We can introduce just about any drug or genetic material that can be encapsulated, and it is delivered to any circulating cells that are specifically targeted," King added.

The technique involves filling the tiny lipid containers, or nanoscale capsules, with a molecular cargo and coating the capsules with adhesive proteins called selectins that specifically bind to target cells. A shunt coated with the capsules is then inserted between a vein and an artery. Much as burrs attach to clothing in a field, the selectin-coated capsules adhere to targeted cells in the bloodstream.

La technique consiste à remplir les petits contenants de lipides, de capsules ou de l'échelle nanométrique, avec une cargaison moléculaire et le revêtement de la capsule avec de la colle que des protéines appelées sélectines lient spécifiquement aux cellules cibles. Un shunt enduit avec les capsules est ensuite inséré entre une veine et une artère. Comme la mousse sur un vêtement, la sélectine adhére aux les cellules dans le sang.

After rolling along the shunt wall, the cells break free from the wall with the capsules still attached and ingest their contents.

Après avoir suivi le mur, les cellules se libèrent avec les capsules et ingèrent leus contenus.

The technique mimics a natural immune response that occurs during inflammation, which stimulates cells on blood vessel walls to express selectins, which quickly form adhesive bonds with passing white blood cells. The white blood cells then stick to the selectins and roll along the vessel wall before leaving the bloodstream to fight disease or infection.

Selectin proteins may be used to specifically target nucleated (cells with a nucleus) cells in the bloodstream.

The study shows that since only the targeted cells ingest the contents of the nanocapsules, the technique could greatly reduce the adverse side effects caused by some drugs.

In a previous paper, King showed how metastasizing cancer cells circulating in the blood stream can stick to selectin-coated devices containing a second protein that programs cancer cells to self-destruct.

Said King, "We've found a way to disable the function of cancer cells without compromising the immune system," which is a problem with many other therapies directed against metastasis.

The current study demonstrates that genetic material can be delivered to targeted cells to turn off specific genes and interfere with processes that lead to disease. The researchers filled nanocapsules with a small-interfering RNA (siRNA) and targeted them to specific circulating cells. When the targeted cells ingested the capsules, the siRNA turned off a gene that produces an enzyme that contributes to the degradation of cartilage in arthritis.

In a similar manner, the method could be used to target the delivery of chemotherapy drugs, vaccine antigens to white blood cells, specific molecules that mitigate auto-immune disorders and more, King said.
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MessageSujet: Moyens de livrer le médicament.   Sam 8 Nov 2008 - 15:38

MIT engineers have outfitted cells with tiny "backpacks" that could allow them to deliver chemotherapy agents, diagnose tumors or become building blocks for tissue engineering.

Les ingénieurs du MIT ont inventé des cellules avec de microscopiques packsacs qui pourraient permettre de livrer les agents de chimiothérapie, de diagnostiquer les maladies ou de devenir des blocs de constructions pour des tissus humains.

Michael Rubner, director of MIT's Center for Materials Science and Engineering and senior author of a paper on the work that appeared online in Nano Letters on Nov. 5, said he believes this is the first time anyone has attached such a synthetic patch to a cell.

C'est la première fois qu'une telle chose est inventée.

The polymer backpacks allow researchers to use cells to ferry tiny cargoes and manipulate their movements using magnetic fields. Since each patch covers only a small portion of the cell surface, it does not interfere with the cell's normal functions or prevent it from interacting with the external environment.

Les packsacs de polymer permettent aux chercheurs d'utiliser les cellules pour transporter de petites charges et manipuler leurs mouvements en utlisants des champs magnétiques. Parce que le packsac ne couvre qu'une petite partie de la cellule, cela ne l'empêche pas ses principales fonctions et interactions.

"The goal is to perturb the cell as little as possible," said Robert Cohen, the St. Laurent Professor of Chemical Engineering at MIT and an author of the paper.

Le but est de perturber la cellule le moins possible.

The researchers worked with B and T cells, two types of immune cells that can home to various tissues in the body, including tumors, infection sites, and lymphoid tissues — a trait that could be exploited to achieve targeted drug or vaccine delivery.

Les chercheurs ont travaillé avec des cellules de type B et T, deux types de cellules qui peuvent se nicher dans différents tissus humains, incluant les tumeurs, les sites d'infection, et les tissus lymphoïdes, ce qui pourrait être utiliser pour faire des médicaments ciblés ou livrer des vaccins.

"The idea is that we use cells as vectors to carry materials to tumors, infection sites or other tissue sites," said Darrell Irvine, an author of the paper and associate professor of materials science and engineering and biological engineering.
Cellular backpacks carrying chemotherapy agents could target tumor cells, while cells equipped with patches carrying imaging agents could help identify tumors by binding to protein markers expressed by cancer cells.

Another possible application is in tissue engineering. Patches could be designed that allow researchers to align cells in a certain pattern, eliminating the need for a tissue scaffold.

The polymer patch system consists of three layers, each with a different function, stacked onto a surface. The bottom layer tethers the polymer to the surface, the middle layer contains the payload, and the top layer serves as a "hook" that catches and binds cells.

Once the layers are set up, cells enter the system and flow across the surface, getting stuck on the polymer hooks. The patch is then detached from the surface by simply lowering the temperature, and the cells float away, with backpacks attached.
"The rest of the cell is untouched and able to interact with the environment," said Albert Swiston, lead author of the paper and a graduate student in materials science and engineering.

The researchers found that T cells with backpacks were able to perform their normal functions, including migrating across a surface, just as they would without anything attached.

By loading the backpacks with magnetic nanoparticles, the researchers can control the cells' movement with a magnetic field.
Because the polymer synthesis and assembly takes place before the patches are attached to cells, there is plenty of opportunity to tweak the process to improve the polymers' effectiveness and ensure they won't be toxic to cells, the researchers say.

Dernière édition par Denis le Sam 28 Juil 2018 - 13:32, édité 17 fois
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