Researchers can deliver RNA, proteins and nanoparticles for many applications


QDOTS imagesCAKXSY1K 8How to squeeze large molecules into cells

By deforming cells, researchers can deliver RNA, proteins and nanoparticles for many applications
January 28, 2013

As cells squeeze through a narrow channel, tiny holes open in their membranes, allowing large molecules such as RNA to pass through (credit: Armon Sharei and Emily Jackson)

Living cells are surrounded by a membrane that tightly regulates what gets in and out of the cell. This barrier is necessary for cells to control their internal environment, but it makes it more difficult for scientists to deliver large molecules such as nanoparticles for imaging, or proteins that can reprogram them into pluripotent stem cells.squeezed_cells

Researchers from MIT have now found a safe and efficient way to get large molecules through the cell membrane, by squeezing the cells through a narrow constriction that opens up tiny, temporary holes in the membrane. Any large molecules floating outside the cell — such as RNA, proteins or nanoparticles — can slide through the membrane during this disruption.

Using this technique, the researchers were able to deliver reprogramming proteins and generate induced pluripotent stem cells with a success rate 10 to 100 times better than any existing method. They also used it to deliver nanoparticles, including carbon nanotubes and quantum dots, which can be used to image cells and monitor what’s happening inside them.

“It’s very useful to be able to get large molecules into cells. We thought it might be interesting if you could have a relatively simple system that could deliver many different compounds,” says Klavs Jensen, the Warren K. Lewis Professor of Chemical Engineering, professor of materials science and engineering, and a senior author of a paper describing the new device in the Proceedings of the National Academy of Sciences.

Robert Langer, the David H. Koch Institute Professor at MIT, is also a senior author of the paper. Lead authors are chemical engineering graduate student Armon Sharei, Koch Institute research scientist Janet Zoldan, and chemical engineering research associate Andrea Adamo.

The new MIT system appears to work for many cell types — so far, the researchers have successfully tested it with more than a dozen types, including both human and mouse cells. It also works in cells taken directly from human patients, which are usually much more difficult to manipulate than human cell lines grown specifically for lab research.

The new device builds on previous work by Jensen and Langer’s labs, in which they used microinjection to force large molecules into cells as they flowed through a microfluidic device. This wasn’t as fast as the researchers would have liked, but during these studies, they discovered that when a cell is squeezed through a narrow tube, small holes open in the cell membrane, allowing nearby molecules to diffuse into the cell.

To take advantage of that, the researchers built rectangular microfluidic chips, about the size of a quarter, with 40 to 70 parallel channels. Cells are suspended in a solution with the material to be delivered and flowed through the channel at high speed — about one meter per second. Halfway through the channel, the cells pass through a constriction about 30 to 80 percent smaller than the cells’ diameter. The cells don’t suffer any irreparable damage, and they maintain their normal functions after the treatment.

Special delivery

The research team is now further pursuing stem cell manipulation, which holds promise for treating a wide range of diseases. They have already shown that they can transform human fibroblast cells into pluripotent stem cells, and now plan to start working on delivering the proteins needed to differentiate stem cells into specialized tissues.

Another promising application is delivering quantum dots — nanoparticles made of semiconducting metals that fluoresce. These dots hold promise for labeling individual proteins or other molecules inside cells, but scientists have had trouble getting them through the cell membrane without getting trapped in endosomes.

In a paper published in November, working with MIT graduate student Jungmin Lee and chemistry professor Moungi Bawendi, the researchers showed that they could get quantum dots inside human cells grown in the lab, without the particles becoming confined in endosomes or clumping together. They are now working on getting the dots to tag specific proteins inside the cells.

The researchers are also exploring the possibility of using the new system for vaccination. In theory, scientists could remove immune cells from a patient, run them through the microfluidic device and expose them to a viral protein, and then put them back in the patient. Once inside, the cells could provoke an immune response that would confer immunity against the target viral protein.

The research was funded by the National Institutes of Health and the National Cancer Institute.

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Introduction to Nanotechnology in Drug Delivery


September 28, 2012 by tildabarliya

Nanotechnology in drug delivery
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Nanotechnology is simply defined as the technology to manipulate the matter on the atomic and/or molecular scale. It is generalized to materials, devices and structures with dimensions sizes at the nanoscale of 1 to 1000 nanometers (nm) (1,2).

Nanotachnology can be applied to many fields including sensors, biomaterials for tissue engineering, and nanostructures or 3D materials for molecular imaging and drug delivery among others. In medicine, nanotechnology is essentially a multidisciplinary field of physics, organic and polymer chemistry as well as molecular biology, pharmacology and engineering. These fields team up together to design a better and most opt treatment option for a disease using “the right drug, the right vehicle and the right route of administration”. In pharmaceutical industries, a new molecular entity (NME) that demonstrates potent biological activity but poor water solubility, or a very short circulating halflife, will likely face significant development challenges or be deemed undevelopable. There is always a degree of compromise, and such tradeoffs may inevitably result in the production of less-ideal drugs. However, with the emerging trends and recent advances in nanotechnology, it has become increasingly possible to address some of the shortcomings associated with potential NMEs. By using nanoscale delivery vehicles, the pharmacological properties (e.g., solubility and circulating half-life) of such NMEs can be drastically improved, essentially leading to the discovery of optimally safe and effective drug candidates. (3,4).

This is just one example which demonstrates the degree to which nanotechnology may revolutionize the rules and possibilities of drug discovery and change the landscape of pharmaceutical industries. (5)

Nanomedicine is facing many challenges in overcoming biological barriers, arrival and accumulation at the target site, therefore advances in nanoparticle engineering, as well as advances in understanding the importance of nanoparticle characteristics such as size, shape and surface properties for biological interactions, are necessary to create new opportunities for the development of nanoparticles for therapeutic applications (6).

Compared to conventional drug delivery, the first generation nanosystems provide a number of advantages. In particular, they can enhance the therapeutic activity by prolonging drug half-life, improving solubility of hydrophobic drugs, reducing potential immunogenicity, and/or releasing drugs in a sustained or stimuli-triggered fashion. Thus, the toxic side effects of drugs can be reduced, as well as the administration frequency. In addition, nanoscale particles can passively accumulate in specific tissues (e.g., tumors) through the enhanced permeability and retention (EPR) effect. Beyond these clinically efficacious nanosystems, nanotechnology has been utilized to enable new therapies and to develop next generation nanosystems for “smart” drug delivery (such as gene theraphy).

In summary; there are several factors that need to be included for a rational nanocarrier design:

–          Protect the drug from premature degradation

–          Protect the drug from premature interaction with biological environment

–          Enhance the absorption of the drug into the selected tissue-site

–          Improve intracellular drug penetration

–          Improve and control the drug pharmacokinetics and distribution profile.

Moreover there are several other factors that need to be taken into consideration to effectively influence the clinical translation of the drug delivery system (DDS) i.e materials that are biodegradable and biocompatible, easily functionalized, exhibit high differential uptake efficiency etc.(7-9).

In the next few chapters, we will try to address some of these factors as well as some examples that succeeded in the clinical setting as well as those who failed.

References:

  1. Nanotechnology and Drug Delivery Part 1: Background and Applications Nelson A Ochekpe, Patrick O Olorunfemi and Ndidi C Ngwuluka.Tropical Journal of Pharmaceutical Research, June 2009; 8 (3): 265-274.http://www.tjpr.org/vol8_no3/2009_8_3_11_Ochekpe.pdf
  2. Davis, M. E., Chen, Z. & Shin, D. M.Nanoparticle therapeutics: an emerging treatment modality for cancer. Nature Rev. Drug Discov. 7, 771–782 (2008).http://www.nature.com/nrd/journal/v7/n9/abs/nrd2614.html
  3. Nanotechnology in Drug Delivery and Tissue Engineering: From Discovery to Applications Jinjun Shi,†,§ Alexander R. Votruba,§ Omid C. Farokhzad,†,§ and Robert Langer*,†,‡. Nano Lett. 2010, 10, 3223–3230.http://engineering.unl.edu/academicunits/chemical-engineering/research/focuslab/kidambi_lab/CHME_896_496_files/Impact%20of%20Nanotechnology%20on%20Drug%20Delivery-Langer_ACSNano’09.pdf
  4. Sengupta, S. et al. Temporal targeting of tumour cells and neovasculature with a nanoscale delivery system. Nature 436, 568–572 (2005)http://www.ncbi.nlm.nih.gov/pubmed/16049491
  5. Torchilin, V. P. Recent advances with liposomes as pharmaceutical carriers. Nature Rev. Drug Discov. 4, 145–160 (2005).http://www.chem.umass.edu/~thompson/Courses/chem697a/papers/TorchilinReviewLiposomeCarriers.pdf
  6. Decuzzi, P. et al. Size and shape effects in the biodistribution of intravascularly injected particles. J. Control. Release 141, 320–327 (2010) http://www.ncbi.nlm.nih.gov/pubmed?term=Decuzzi%2C%20P.%20et%20al.%20Size%20and%20shape%20effects%20in%20the%20biodistribution%20of%20intravascularly%20injected%20particles.%20J.%20Control.%20Release%20141%2C%20320%E2%80%93327%20(2010)
  7. Nanocarriers as an emerging platform for cancer therapy. Dan Peer1†, Jeffrey M. Karp2,3†, Seungpyo Hong4†, Omid C. Farokhzad5, Rimona Margalit6 and Robert Langer3,4*. nature nanotechnology 2007 |  vol 2 751-760.http://www.nature.com/nnano/journal/v2/n12/abs/nnano.2007.387.html
  8. Alonso, M. J. Nanomedicines for overcoming biological barriers. Biomed. Pharmacother. 58, 168–172 2004.http://www.ncbi.nlm.nih.gov/pubmed/15082339
  9. Torchilin, V. P. Recent advances with liposomes as pharmaceutical carriers. Nat. Rev. Drug Discov.4, 145–160 (2005) http://www.chem.umass.edu/~thompson/Courses/chem697a/papers/TorchilinReviewLiposomeCarriers.pdf

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