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© 2011, 2012 Health Futures Digest
| The launch of another well-pedigreed journal devoted to nanomedicine is not the only further evidence of nanomedicine’s arrival. The US National Cancer Institute’s bold new plan to put an end to lung cancer by 2015, and its significant new funding of nanomedical approaches to cancer research, clinches it.
Signs that the nanomedical approach will pay off, for cancer and other diseases, include the following:
But are nanotubes and other types of nano-engineered drug delivery mechanisms safe? A new class of synthetic biocoatings could make sure. |
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| Nanomedicine On a Roll
The editor of the new international peer-reviewed journal NanoBiotechnology anticipates “explosive growth” to result from the convergence of nanotechnology and biomedical sciences. The journal will cover molecular bioprobes, nanoparticles and nanobiosystems, nanobiomaterials, biomolecular assemblies and supra-biomolecules, nanobiosensors and nanobiochips, BioNEMS and nano-biofluidics, nanobiophotonics, single-molecule detection and manipulation, and molecular motors. More than 40 prestigious international academic institutions are represented on the editorial board. The US National Cancer Institute has announced a plan to effectively end lung cancer by 2015, through a combination of better tobacco control, early detection, and targeted nanotherapies. Nanotechnology for early diagnosis is the centerpiece, according to NCI’s deputy director, who said: “We want to change lung cancer from a high mortality disease into a treatable, low mortality disease.” NIH Funds Cancer Nanomed Institute Caltech’s new Nanosystems Biology Cancer Center is off to a good start with a US$3.6 million National Cancer Institute (NCI) grant and a co-chair in the person of systems biology guru Leroy Hood. The center will focus on prostate and ovarian cancer, glioblastoma, and melanoma. All told, the NCI gave awards totaling $26.3 million to seven Centers of Cancer Nanotechnology Excellence, the others centers being at the University of North Carolina, UC San Diego, Emory University-Georgia Tech, MIT-Harvard, Northwestern University, and Washington University in St. Louis. Over five years, the NCI will spend $144.3 million for nanotechnology in cancer research. American Academy of Nanomedicine Meeting 170 researchers attended the American Academy of Nanoscience’s first annual conference in August. They concentrated mainly on cancer. One described a nanoparticle known as a liposome designed to find a tumor, attach itself, and open a pathway for chemicals and radiation. The liposomes don’t cure the cancer, but they make chemotherapy and radiation more effective. In mice, the therapy was successful for head and neck, pancreatic, and prostate cancers. The treatment is now in Phase I clinical trials. Another Promising Cancer Therapy; and a Vaccine? Australian researchers have developed an “extremely accurate” and “most specific ever” technique for targeting and killing cancer cells with radiation without affecting surrounding health tissues, according to an AFP wire story. The radiation irradiates a volume of only one millionth of a millimeter. They used “antibodies and DNA attached to a radioactive atom” to identify and kill the cancerous cells. The technique worked in the laboratory and could undergo clinical trials within five years. Still, it would be better to prevent cancers arising in the first place. US researchers have synthesized a cancer vaccine from an oligosaccharide, a peptide, and a lipopeptide. The combination helps the body’s immune system recognize a cancer more clearly. Mice immunized with the vaccine formed antibodies against an antigen that is present in large numbers on the surface of certain human tumor cells but not present on healthy cells, proving in principle that the vaccine elicits an immune response against tumor antigens. Carbon Nanoneedles for Injecting Drugs into Cells French and Italian researchers have successfully used carbon nanotubes as the equivalent of cellular syringes containing antimycotics (antifungal agents). However, in this case the drugs are attached to the outside of the syringe. Carbon nanotubes can penetrate targeted cell membranes like tiny needles without damaging the cell, taking their molecular drug payload in with them. The researchers attached two different drug molecules to each nanotube, demonstrating the potential of the method for combination therapies or to trace the uptake of a drug by using a marker. Their experiment used nanotubes with the antimycotic amphotericin B and a fluorescence marker dye. When attached to the nanotubes, it turns out the amphotericin B loses its usual toxic side effects, yet its effectiveness against fungi is improved. Another, now feasible, approach would be to attach a drug and a molecule to “guide” the nanotubes to specific types of cells, such as tumor cells. Carbon Nanotubes Kill Cancer Cells Carbon nanotubules inserted into cancer cells then exposed to near-infra red light from a laser heat up to about 70 degrees C in two minutes and kill the cell, Stanford University researchers found. To get the nanotubes into cancer cells, and not into healthy cells, they coated the nanotubes with folate molecules, which readily attach to receptors that coat the surface only of cancer cells, which then absorb the folate and with it the nanotubes. By attaching specific antibodies to the nanotubes, the researchers hope to target specific types of cancer cell and have already begun work to use that method against lymphoma in mice. “Smart” bionanotubes made of lipid proteins can be made with the equivalent of lids that would open or close to deliver drugs or genes. University of California scientists are already using the cancer drug Taxol in experiments to stabilize and lengthen the nanotubes. A team of Purdue University scientists skilled in building things at nanoscale have built triangles out of three strands of RNA that can carry therapeutic agents directly to infected cells, offering a potential wealth of new treatments for chronic diseases. Small enough to pass through a cell membrane, they can carry other strands of therapeutic RNA inside with them. The RNA nanoparticles have successfully halted cancer growth in mice and in lab-grown human cells. One of their most significant benefits is their ability to deliver multiple therapeutic agents directly into specific cancer cells, to perform different tasks. The first task is to recognize the cancer cell and gain access to its interior. The second is to destroy it. The third is to “leave a trail,” as the lead researcher put it, so doctors can trace the outcome after treatment. The scientists have already demonstrated delivery of three different therapeutic agents into a cell at the same time. They used “small interfering RNA” (siRNA) to deactivate certain genes in cells, RNA “aptamers” to bind to cancer cell surface markers, and ribozymes to degrade specific RNA in cancer cells or viruses. They combined all three into triangles measuring between 25 and 40 nanometers wide, the perfect size –. not too big to pass through cell membranes, not so small they would tend to be filtered out by the body. Not only did this method succeed in interrupting the growth of human breast cancer cells and leukemia model lymphocytes in laboratory experiments, but also completely blocked cancer development in living mice that were in the process of developing cancer. Though toxicity was not found in the experiments, the researchers caution that more work is needed to be certain, and in addition they say they need to find better ways to protect the RNA from degradation by enzymes in the body. Silver nanoparticles less than 10 nanometers in diameter and coated with “foamy carbon” have been successfully attached to the HIV-1 virus, preventing it from bonding to host cells. The work was conducted jointly by the University of Texas and Mexico University. Further study, particularly on the long-term effects, is still needed, though a preventive cream for HIV-1 is being developed for human testing, and silver nanoparticles are also being tested against other viruses and the “superbug” (Methicillin resistant staphylococcus aureus). Silver Nanobullet for Hospital Infections Silver nanoparticles could help fight hospital-related infections and have a dramatic impact on the medical-device market, which is responsible for many infections introduced by catheters and other medical devices that pass through the skin and offer surfaces where germs can grow into “biofilms.” The company marketing the nanoparticles says a typical infection can cost as much as US$47,000 per patient to treat, and in the state of Pennsylvania alone that amounts to $2 billion in added hospital charges. In minute concentrations, silver is highly toxic to germs while relatively non-toxic to human cells. AcryMed has devised a technique to coat medical-device surfaces with anti-microbial silver particles 2 to 20 nanoparticles in size that prevent biofilms from forming. The coating method does not require expensive vacuum chambers and high temperatures. Cheap Golden Thermal Nanoshells Having earlier shown how gold nanoparticles could detect cancer by binding to malignant cells, a father-and-son research team at the Georgia Institute of Technology and the University of California, respectively, have shown how the nanoparticles can be heated with a laser to destroy oral squamous carcinoma cell lines without destroying adjacent benign tissue. They believe their inexpensive technique “holds great promise for a number of types of cancer.” University of California researchers have used carbon nanotubes as super-strong scaffolds for bone regrowth. The nanotubes substitute for collagen, an organic substance on which inorganic crystals of hydroxyapatite grow to form bone. The nanotubes were chemically treated to attract hydroxyapatite. Besides the potential benefits to patients with bone problems, the research is a proof of concept that nanotubes could be made to attract, grow, and direct all sorts of minerals. Still to be determined before the technique could be used in patients is whether the nanotubes cause any harm in the body, how to introduce them reliably at the site of bone trauma or degradation, and whether nanotube-enhanced bone would actually be too strong and cause damage to adjacent natural bone. Biocompatible Nanomedicine Carriers Researchers at the University of California at Irvine have synthesized a new class of biomaterials made of sugar and peptide building blocks that are as versatile as synthetic polymers, meaning that their composition, structure, and properties are easy to control. The new biopolymers have the advantage over other synthetic polymers of being biocompatible and biodegradable. The researchers’ first biomaterials, made of the sugar galactose and short peptides that comprise the amino acid lysine, may be able to act as gene transporters because the material “wraps” DNA into little packages that are taken up into cells. It did not induce any immunological reactions in rats, and unlike gene transporters such as polylysine, made exclusively of lysine building blocks, it is not toxic to cells even at high concentrations. The researchers are now developing a family of sugar-peptide biomaterials for use in tissue engineering and drug/gene delivery. |
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