Coated nanoparticles move easily into brain tissue

Real-time imaging of nanoparticles green) coated with polyethylene-glycol (PEG), a hydrophilic, non-toxic polymer, penetrate within normal rodent brain. Without the PEG coating, negatively charged, hydrophobic particles (red) of a similar size do not penetrate. Image by Elizabeth Nance, Kurt Sailor, Graeme Woodworth.

Johns Hopkins researchers report they are one step closer to having a drug-delivery system flexible enough to overcome some key challenges posed by brain cancer and perhaps other maladies affecting that organ. In a report published online Aug. 29 in Science Translational Medicine, the Johns Hopkins team says its bioengineers have designed nanoparticles that can safely and predictably infiltrate deep into the brain when tested in rodent and human tissue.

“We are pleased to have found a way to prevent drug-embedded particles from sticking to their surroundings so that they can spread once they are in the brain,” said Justin Hanes, Lewis J. Ort Professor of Ophthalmology and project leader in the Johns Hopkins Center of Cancer Nanotechnology Excellence.

Standard protocols following the removal of brain tumors include chemotherapy directly applied to the surgical site to kill any cancer cells left behind. This method, however, is only partially effective because it is hard to administer a dose of chemotherapy high enough to sufficiently penetrate the tissue to be effective and low enough to be safe for the patient and healthy tissue. Furthermore, previous versions of drug-loaded nanoparticles typically adhere to the surgical site and do not penetrate into the tissue.

These newly engineered nanoparticles overcome this challenge. Elizabeth Nance, a graduate student in chemical and biomolecular engineering, and Johns Hopkins neurosurgeon Graeme Woodworth, suspected that drug penetration might be improved if drug-delivery nanoparticles interacted minimally with their surroundings. Nance achieved this by coating nano-scale beads with a dense layer of PEG or poly(ethylene glycol). The team then injected the coated beads, which had been marked with a fluorescent tag,  into slices of rodent and human brain tissue. They found that a dense coating of PEG allowed larger beads to penetrate the tissue, even those beads that were nearly twice the size previously thought to be the maximum possible for penetration within the brain. They then tested these beads in live rodent brains and found the same results.

Elizabeth Nance. Photo by Ming Yang.

The results were similar when biodegradable nanoparticles carrying the chemotherapy drug paclitaxel and coated with PEG were used. “It’s really exciting that we now have particles that can carry five times more drug, release it for three times as long and penetrate farther into the brain than before,” said Nance. “The next step is to see if we can slow tumor growth or recurrence in rodents.”

Woodworth added that the team “also wants to optimize the particles and pair them with drugs to treat other brain diseases, like multiple sclerosis, stroke, traumatic brain injury, Alzheimer’s and Parkinson’s.” Another goal for the team is to be able to administer their nanoparticles intravenously, which is research they have already begun.

Additional authors on the paper include Kurt Sailor, Ting-Yu Shih, Qingguo Xu, Ganesh Swaminathan, Dennis Xiang, and Charles Eberhart, all from The Johns Hopkins University.

Story adapted from an original press release by Cathy Kolf.


Additional news coverage of this research can be found at the following links:

Nanotechnology/Bio & Medicine

Death and Taxes Mag

New Scientist Health

Nanotech Web

Portugese news release (in Portugese)

German Public Radio (in German)

Light-activated synthetic protein illuminates disease destruction

Illustration of collagen’s rope-like structure. Click to watch video. (INBT Animation Studios)

Johns Hopkins researchers have created a synthetic protein that, when activated by ultraviolet light, can guide doctors to places within the body where cancer, arthritis and other serious medical disorders can be detected. The synthetic protein does not zero in directly on the diseased cells. Instead, it binds to nearby collagen that has been degraded by disease or injury.

“These disease cells are like burglars who break into a house and do lots of damage but who are not there when the police arrive,” said S. Michael Yu, a faculty member in the Whiting School of Engineering’s Department of Materials Science and Engineering. “Instead of looking for the burglars, our synthetic protein is reacting to evidence left at the scene of the crime,” said Yu, who was principal investigator in the study.

The technique could lead to a new type of diagnostic imaging technology and may someday serve as a way to move medications to parts of the body where signs of disease have been found. In a study published in the Aug. 27-31 Online Early Edition of Proceedings of the National Academy of Sciences, the researchers reported success in using the synthetic protein in mouse models to locate prostate and pancreatic cancers, as well as to detect abnormal bone growth activity associated with Marfan syndrome.

Collagen, the body’s most abundant protein, provides structure and creates a sturdy framework upon which cells build nerves, bone and skin. Some buildup and degradation of collagen is normal, but disease cells such as cancer can send out enzymes that break down collagen at an accelerated pace. It is this excessive damage, caused by disease, that the new synthetic protein can detect, the researchers said.

A key collaborator was Martin Pomper, a School of Medicine professor of radiology and co-principal investigator of the Johns Hopkins Center of Cancer Nanotechnology Excellence. Pomper and Yu met as fellow affiliates of the Johns Hopkins Institute for NanoBioTechnology. “A major unmet medical need is for a better non-invasive characterization of disrupted collagen, which occurs in a wide variety of disorders,” Pomper said. “Michael has found what could be a very elegant and practical solution, which we are converting into a suite of imaging and potential agents for diagnosis and treatment.”

The synthetic proteins used in the study are called collagen mimetic peptides or CMPs. These tiny bits of protein are attracted to and physically bind to degraded strands of collagen, particularly those damaged by disease. Fluorescent tags are placed on each CMP so that it will show up when doctors scan tissue with fluorescent imaging equipment. The glowing areas indicate the location of damaged collagen that is likely to be associated with disease.

In developing the technique, the researchers faced a challenge because CMPs tend to bind with one another and form their own structures, similar to DNA, in a way that would cause them to ignore the disease-linked collagen targeted by the researchers.

To remedy this, the study’s lead author, Yang Li, synthesized CMPs that possess a chemical “cage” to keep the proteins from binding with one another. Just prior to entering the bloodstream to search for damaged collagen, a powerful ultraviolet light is used to “unlock” the cage and allow the CMPs to initiate their disease-tracking mission. Li is a doctoral student from the Department of Chemistry in the Krieger School of Arts and Sciences at Johns Hopkins. Yu, who holds a joint appointment in that department, is his doctoral adviser.

Yu’s team tested Li’s fluorescently tagged and caged peptides by injecting them into lab mice that possessed both prostate and pancreatic human cancer cells. Through a series of fluorescent images taken over four days, researchers tracked single strands of the synthetic protein spreading throughout the tumor sites via blood vessels and binding to collagen that had been damaged by cancer.

Similar in vivo tests showed that the CMP can target bones and cartilage that contain large amounts of degraded collagen. Therefore, the new protein could be used for diagnosis and treatment related to bone and cartilage damage.

Although the process is not well understood, the breakdown and rebuilding of collagen is thought to play a role in the excessive bone growth found in patients with Marfan syndrome. Yu’s team tested their CMPs on a mouse model for this disease and saw increased CMP binding in the ribs and spines of the Marfan mice, as compared to the control mice.

Funding for the research was provided by the National Science Foundation, the National Institutes of Health and the Department of Defense. The synthetic protein process used in this research is protected by patents obtained through the Johns Hopkins Technology Transfer Office.

Along with Yu, Li and Pomper, co-authors of this study were instructor Catherine A. Foss and medical resident Collin M. Torok from the Department of Radiology and Radiological Science at the Johns Hopkins School of Medicine; Harry C. Dietz, a professor, and Jefferson J. Doyle, a doctoral student, both of the Howard Hughes Medical Institute and Institute of Genetic Medicine at the School of Medicine; and Daniel D. Summerfield a former master’s student in the Department of Materials Science and Engineering.

Adapted from an original press release by Phil Sneiderman.


Killing prostate cancer cells with out harming the healthy cells

Experimenting with human prostate cancer cells and mice, cancer imaging experts at Johns Hopkins say they have developed a method for finding and killing malignant cells while sparing healthy ones.

The method, called “theranostic” imaging, targets and tracks potent drug therapies directly and only to cancer cells. It relies on binding an originally inactive form of drug chemotherapy, with an enzyme, to specific proteins on tumor cell surfaces and detecting the drug’s absorption into the tumor. The binding of the highly specific drug-protein complex, or nanoplex, to the cell surface allows it to get inside the cancerous cell, where the enzyme slowly activates the tumor-killing drug.

Researchers say their findings, published in the journal American Chemical Society Nano online Aug. 6, are believed to be the first to show that chemotherapies can be precisely controlled at the molecular level to maximize their effectiveness against tumors, while also minimizing their side effects.

Senior study investigator Zaver Bhujwalla, Ph.D., a professor at the Johns Hopkins University School of Medicine and its Kimmel Cancer Center, notes that a persistent problem with current chemotherapy is that it attacks all kinds of cells and tissues, not just cancerous ones.

In the theranostic imaging experiments, overseen by Bhujwalla and study co-investigator Martin Pomper, M.D., Ph.D., investigators directed drugs only to cancer cells, specifically those with prostate-specific membrane antigen, or PSMA cell surface proteins. Both Pomper and Bhujwalla are affiliated faculty members of Johns Hopkins Institute for NanoBioTechnology.

“Our results show a non-invasive imaging approach to following and delivering targeted therapy to any cancer that expresses PSMA,” says Bhujwalla, who also serves as director of the Johns Hopkins In Vivo Cellular and Molecular Imaging Center (ICMIC), where the theranostic imaging studies were developed.

Bhujwalla says the new technique potentially will work against any cancer in which tumors elevate production of certain cell surface proteins. Examples would include breast cancers with HER-2/neu and CXCR4 proteins, and some liver, lung and kidney cancers also known to express particular proteins. She notes that PSMA is expressed in the vessels of most solid tumors, suggesting that the nanoplex reported in the latest study could be used in general to image and treat a variety of cancers.

In their latest series of experiments, primarily in mice injected with human prostate tumor cells, Bhujwalla and the Johns Hopkins team tested their ability to track with imaging devices the delivery of anti-cancer drugs directly to tumors. Some of the tumors comprised cells with PSMA, while other so-called control tumors had none. Included in the drug nanoplex were small strands of RNA, cell construction acids that can be used instead to block and turn down production of a well-known enzyme, choline kinase, whose levels usually rise with tumor growth. All nanoplex components were imaged inside the tumor, in addition to dropping choline kinase production, which decreased by 80 percent within 48 hours of nanoplex absorption into cells with ample PSMA. When researchers used antibodies to block the action of PSMA, down went the level of nanoplex uptake and drug activation in cancerous cells as measured by dimming of the image.

Different concentrations of the drug nanoplex, tagged with radioactive and fluorescent molecules, were mixed in the lab with prostate cancer tissue cells, some of which had extra PSMA and others which had none. Only those cells with extra PSMA showed nanoplex uptake, as measured by image intensity, which later decreased when PSMA-blocking chemicals were added (back to levels seen in cells with almost no PSMA).

Additional experiments involving injections of three different concentrations of the drug nanoplex showed no damage to other vital mouse organs, such as the kidney and liver, nor any uptick in the mouse immune system response.

“Our theranostic imaging approach shows how the best methods of detection and treatment can be combined to form highly specialized, more potent and safer forms of chemotherapy,” says Pomper, a professor at Johns Hopkins who also serves as an associate director at ICMIC.

He says that an important goal for theranostic imaging is to move it beyond standard chemotherapy that attacks one target molecule at a time.

“With theranostic imaging, we can attack multiple tumor targets, making it harder for the tumor to evade drug treatment,” says Pomper, who is already working with colleagues at Johns Hopkins to identify other molecular targets.

The most recent studies were performed at Johns Hopkins over two years, starting in 2010, with funding support from the National Cancer Institute, part of the National Institutes of Health. The corresponding grant numbers are P50-CA103175, RO1-CA138515 and RO1-CA134675.

In addition to Bhujwalla and Pomper, other Johns Hopkins researchers from the Russell H. Morgan Department of Radiology involved in this imaging study were lead investigators Zhihang Chen, Ph.D., and Mary-France Penet, Ph.D. Additional study co-investigators were Sridhar Nimmagadda, Ph.D.; Li Cong, Ph.D.; Sangeeta Banerjee, Ph.D.; Paul Winnard Jr., Ph.D.; Dmitri Artemov, Ph.D.; and Kristine Glunde, Ph.D.

Press release by David March

Therapeutic nanolex containing multi-modal imaging reporters targeted to prostate specific membrane antigen (PSMA), which is expressed on the cell surface of castrate resistant PCa. (Image by Chen et al. from ACS Nano 2012).


Tumor cells change when put into a ‘tight spot’

Konstantinos Konstantopoulos addresses audience at 2012 NanoBio Symposium. Photo by Mary Spiro/JHU

“Cell migration represents a key aspect of cancer metastasis,” said Konstantinos Konstantopoulos, professor and chair of the Department of Chemical and Biomolecular Engineering at Johns Hopkins University. Konstantopoulos was among the invited faculty speakers for the 2012 NanoBio Symposium.

Cancer metastasis, the migration of cancer cells from a primary tumor to other parts of the body, represents an important topic among professors affiliated with Johns Hopkins Institute for NanoBioTechnology. Surprisingly, 90 percent of cancer deaths are caused from this spread, not from the primary tumor alone. Konstantopoulos and his lab group are working to understand the metastatic process better so that effective preventions and treatments can be established. His students have studied metastatic breast cancer cells in the lab by tracking their migration patterns. The group has fabricated a microfluidic-based cell migration chamber that contains channels of varying widths. Cells are seeded at one opening of the channels, and fetal bovine serum is used as a chemoattractant at the other opening of the channels to induce the cells to move across. These channels can be as big as 50 µm wide, where cells can spread out to the fullest extent, or as small as 3 µm wide, where cells have to narrowly squeeze themselves to fit through.

A current dogma in the field of cell migration is that actin polymerization and actomyosin contractility give cells the flexibility they need to protrude and contract across a matrix in order to migrate. When Konstantopoulos’s students observed cells in the wide, 50 µm-wide channels, they saw actin distributed over the entirety of the cells, as expected. They also observed that when the cells were treated with drugs that inhibited actin polymerization and actomyosin contractility, they did not migrate across the channels, also as expected.

However, when the students observed cells in the narrow, 3 µm-wide channels, they were surprised to see actin only at the leading and trailing edges of the cells. Additionally, the inhibition of actin polymerization and actomyosin contractility did not affect the cells’ ability to migrate.

“Actin polymerization and actomyosin contractility are critical for 2D cell migration but dispensable for migration through narrow channels,” concluded Konstantopoulos. The data challenged what many had previously believed about cell migration by showing that cells in confined spaces did not need these actin components to migrate.

These findings are indeed important in the context of cancer metastasis, where cells must migrate through a heterogeneous environment of both wide and narrow areas. Konstantopoulos’s data gives a better mechanistic understanding of the different methods cancer cells use to migrate in diverse surroundings.

Future studies in the Konstantopoulos lab will focus on how tumor cells decide which migratory paths to take. INBT-sponsored graduate student Colin Paul has developed an additional microfluidic device that contains channels with bifurcations. He hopes to determine what factors guide a cell in one direction versus another. The Konstantopoulos lab hopes to continue to understand exactly how tumor cells migrate so that new therapies can eventually be developed to stop metastasis.

Story by Allison Chambliss, a Ph.D. student in the Department of Chemical and Biomolecular Engineering with interests in cellular biophysics and epigenetics.

Watch a video related to this research here.

Konstantopoulos reported these findings in October 2012 The Journal of the Federation of American Societies for Experimental Biology.  Read the article online here.


Nanoparticles slip through mucus barrier to protect against herpes virus

“Thick, sticky mucus layers limit effectiveness of drug delivery to mucosal tissues. Mucus-penetrating particles or MPPs (in red) are able to penetrate mucus, covering the entire surface of the mouse vagina (in blue). Improved distribution and retention of MPPs led to significantly increased protection in a mouse model for herpes simplex virus infection. Image by Laura Ensign.

Johns Hopkins researchers say they have demonstrated for the first time, in animals, that nanoparticles can slip through mucus to deliver drugs directly to tissue surfaces in need of protection.

The researchers used these mucus-penetrating particles, or MPPs, to protect against vaginal herpes infections in mice. The goal is to create similar MPPs to deliver drugs that protect humans against sexually transmitted diseases or even treat cancer.

“This is the first in vivo proof that MPPs can improve distribution, retention, and protection by a drug applied to a mucosal surface, said Justin Hanes, Ph.D., a professor of ophthalmology at the Johns Hopkins Wilmer Eye Institute and director of the Center for Nanomedicine at the Johns Hopkins University School of Medicine.

Hanes also is a principal investigator with the Johns Hopkins Center of Cancer Nanotechnology Excellence. Results of his team’s experiments are described in the June 13 issue of the journal Science Translational Medicine.

The moist mucosal surfaces of the body, like the eyes, lungs, intestines and genital tract, are protected from pathogens and toxins by layers of moist sticky mucus that is constantly secreted and shed, forming our outermost protective barrier.

“Although many people associate mucus with disgusting cold and cough symptoms, mucus is in fact a sticky barrier that helps keep you healthy,” says Laura Ensign, a doctoral student affiliated with the Center for Nanomedicine at the School of Medicine and with the Department of Chemical and Biomolecular Engineering at Johns Hopkins’ Whiting School of Engineering. She is the lead author of the journal report.

Unfortunately, Ensign noted, mucus barriers also stop helpful drug delivery, especially conventional nanoparticles intended for sustained drug delivery. In a Johns Hopkins laboratory, researchers developed nanoparticles that do not stick to mucus so they can slip through to reach the cells on the mucosal surface, in this case the surface of the mouse vagina, she added.

Ensign explained that conventional nanoparticles actually stick to mucus before releasing their drug payload and are then removed when the mucus is replenished, often within minutes to hours. Working with researchers in the laboratory of Richard Cone, Ph.D., in the Department of Biophysics in the university’s Krieger School of Arts and Sciences, the Hanes team fabricated particles with surface chemistry that mimics a key feature of viruses that readily infect mucosal surfaces.

“Richard Cone’s lab found that viruses, such as the human papilloma virus, could diffuse through human cervical mucus as fast as they diffuse through water. These ‘slippery viruses’ have surfaces that are ‘water-loving,’ ” Hanes said. “In contrast, many nanoparticles intended to deliver drugs to mucosal surfaces are ‘mucoadhesive’ and ‘oil-loving,’ but these nanoparticles stick to the superficial layers of the mucus barrier, the layers that are most rapidly removed.”

To make their mucus-penetrating particles, the team transformed conventional ‘oil-loving’ nanoparticles by coating them with a substance used in many commercial pharmaceutical products: polyethylene glycol. PEG makes the particles “water-loving,” like the viruses that slip right through mucus.

“The key is that the nanoparticles, like viruses, have to be small enough to go through the openings in the mucus mesh, and also have surfaces that mucus can’t stick to. If you think about it,” said Ensign, “mucus sticks to almost everything.”

“Viruses have evolved over millions of years to become slippery pathogens that readily penetrate our protective mucus barriers,” said Cone, “and engineering nanoparticles that penetrate the mucus barrier just like viruses is proving to be a clever way to deliver drugs.”

Hanes emphasized that the MPPs provided greatly improved protective efficacy while at the same time reducing the effective dose of drug needed 10-fold. Furthermore, Hanes added, the MPPs “continue to supply drug for at least a day and provide nearly 100 percent coverage of the mucosal surface of the vagina and ectocervix” in their laboratory mice.

“We’ve shown that mucus-penetrating particles are safe for vaginal administration in mice. Our next move will be to show that they are safe for vaginal administration in humans,” Ensign said. “Now our laboratory currently is working on an MPP formulation of a drug that protects against HIV infection that we hope will be tested in humans.”

Their technology could lead to a once-daily treatment for preventing sexually transmitted diseases, for contraception and for treatment of cervico-vaginal disorders, Ensign said.

Ensign added that MPP technology has the potential to prevent a wide range of mucosal diseases and infections, including chronic obstructive pulmonary disease, lung cancer, and cystic fibrosis,” Ensign said.

Additional authors on the paper include postdoctoral fellow Ying-Ying Wang and research specialist Timothy Hoen from the Department of Biophysics; former master’s student Terence Tse from the Department of Chemical and Biomolecular Engineering; and Benjamin Tang, formerly of Johns Hopkins School of Medicine and currently at the Massachusetts Institute of Technology.

Under a licensing agreement between Kala Pharmaceuticals and the Johns Hopkins University, Hanes is entitled to a share of royalties received by the university on sales of products used in the study.

Hanes and the university own Kala Pharmaceuticals stock, which is subject to certain restrictions under university policy. Hanes is also a founder, a director and a paid consultant to Kala Pharmaceuticals. The terms of this arrangement are being managed by The Johns Hopkins University in accordance with its conflict of interest policies.”

Story by Mary Spiro

Additional news coverage of this research may be found at the following links:

WYPR: The Mucus Ruse

Scientific American


Meet INBT’s summer interns, already digging into their research

Research does not take a holiday during the summer at Johns Hopkins University in Baltimore, Md. In fact, it ramps up with the addition of many new faces from across the country.

The Johns Hopkins Institute for NanoBioTechnology summer research interns have arrived and are already busy at work in various laboratories. This year’s group is the largest the institute has ever hosted, with 17 undergraduates from universities nationwide.

Of the total, three students are affiliated with the Center of Cancer Nanotechnology Excellence and four are affiliated with the Physical Sciences-Oncology Center. The remaining 10 are part of the National Science Foundation Research Experience for Undergraduates program. All are hosted through INBT, which serves as a hub for their academic and social activities.

INBT summer interns conduct 10 weeks of research in a laboratory either on the Homewood or the medical campus of the University. At the end of that time, students have learned how to work in a multidisciplinary team and how to manage a short term research project.  They also discover if research is a pathway they want to pursue after earning their bachelor’s degrees.

In August, interns from many of the science, medicine, engineering and public health summer programs will gather for a  poster session to be held on August 2 at 3 p.m. in Turner Concourse. The poster session will allow students to show off the results of their their work.

This year’s INBT/PS-OC/CCNE interns include:

At the Whiting School of Engineering…

Amani Alkayyali from Wayne State University is an REU student in the laboratory of Honggang Cui assistant professor in the Department of Chemical and Biomolecular Engineering. Also in the Cui lab are CCNE intern Matthew Fong from the University of California, Berkeley and Michelle LaComb, an REU student from Rice University.

Sharon Gerecht, assistant professor in the Department of Chemical and Biomolecular engineering, is hosting three interns. Josh Porterfield of Cornell University and Carolyn Zhang from the University of California, San Diego are both PS-OC interns, and Bria Macklin of Howard University is an REU intern.

Jacqueline Carozza of Cornell University is a PS-OC student working in the lab of Denis Wirtz, professor in the Department Chemical and Biomolecular Engineering. Cassandra Loren from Oregon State University is a PS-OC intern also working in the Wirtz lab.

Eric Do from the University of Washington is an REU working in the lab of assistant professor Margarita Herrara-Alonso in the Department of Materials Science and Engineering.

Olivia Hentz from Cornell is an REU student working in the lab of Jonah Erlebacher, professor in the Department of Materials Science and Engineering.

Justin Samorajski from the University of Dallas is a returning summer intern, once again working in the materials science and engineering lab of professor Peter Searson as part of the CCNE.

At the School of Medicine…

Lauren Lee of Cornell University is an REU working in the lab of biomedical engineering lab of associate professor Hai-Quan Mao.

Albert Lu from the University of California Berkeley is a CCNE intern working in the biomedical engineering lab of associate professor Jeff Wang.

Bianca Lascano from Norfolk State University is an REU in assistant professor Jordan Green’s biomedical engineering lab.

Charlie Nusbaum of the Richard Stockton College is an REU intern in the radiation oncology lab of assistant professor Robert Ivkov.

At the Krieger School of Arts and Sciences…

Anthony Loder of Rowan University is an REU working in the biology lab of assistant professor Xin Chen.

Daniel McClelland is also REU from Bethany College works in the chemistry laboratory of professor Howard Fairbrother.



Device with tiny ‘speed bumps’ sorts cells

These illustrations show magnetically labeled circulating tumor cells (shown as yellow spheres), together with red, white and platelet cells, attempting to travel over an array of slanted ramps. The ramps act as speed bumps, slowing the tumor cells.. (Illustration by Martin Rietveld)

In life, we sort soiled laundry from clean; ripe fruit from rotten. Two Johns Hopkins engineers say they have found an easy way to use gravity or simple forces to similarly sort microscopic particles and bits of biological matter—including circulating tumor cells.

In the May 25 online issue of Physical Review LettersGerman Drazer, an assistant professor of chemical and biomolecular engineering, and his doctoral student, Jorge A. Bernate, reported that they have developed a lab-on-chip platform, also known as a microfluidic device, that can sort particles, cells or other tiny matter by physical means such as gravity. By moving a liquid over a series of micron-scale high diagonal ramps—similar to speed bumps on a road—the device causes microscopic material to separate into discrete categories, based on weight, size or other factors, the team reported.

As the tumor cells slow, the flow carries them along the length of the ramp, causing lateral displacement. After the tumor cells traverse an array of these ramps, they have sufficiently been displaced and can be continuously isolated from other cells in the sample. (Illustration by Martin Rietveld)

The process described in the journal article could be used to produce a medical diagnostic tool, the Whiting School of Engineering researchers say. “The ultimate goal is to develop a simple device that can be used in routine checkups by health care providers,” said doctoral student Bernate, who is lead author on the paper. “It could be used to detect the handful of circulating tumor cells that have managed to survive among billions of normal blood cells. This could save millions of lives.”

Ideally, these cancer cells in the bloodstream could be detected and targeted for treatment before they’ve had a chance to metastasize, or spread cancer elsewhere. Detection at early stages of cancer is critical for successful treatment.

How does this sorting process occur? Bernate explained that inside the microfluidic device, particles and cells that have been suspended in liquid flow along a “highway” that has speed-bump-like obstacles positioned diagonally, instead of perpendicular to, the path. The speed bumps differ in height, depending on the application.

“As different particles are driven over these diagonal speed bumps, heavier ones have a harder time getting over than the lighter ones,” the doctoral student said. When the particles cannot get over the ramp, they begin to change course and travel diagonally along the length of the obstacle. As the process continues, particles end up fanning out in different directions.

“After the particles cross this section of the ‘highway,’” Bernate said, “they end up in different ‘lanes’ and can take different ‘exits,’ which allows for their continuous separation.”

Gravity is not the only way to slow down and sort particles as they attempt to traverse the speed bumps. “Particles with an electrical charge or that are magnetic may also find it hard to go up over the obstacles in the presence of an electric or magnetic field,” Bernate said. For example, cancer cells could be “weighted down” with magnetic beads and then sorted in a device with a magnetic field.

The ability to sort and separate things at the micro- and nanoscale is important in many industries, ranging from solar power to bio-security. But Bernate said that a medical application is likely to be the most promising immediate use for the device.

He is slated to complete his doctoral studies this summer, but until then, Bernate will continue to collaborate with researchers in the lab of Konstantinos Konstantopoulos, professor and chair of the Department of Chemical and Biomolecular Engineering, and with colleagues at InterUniversity Microelectronics Center, IMEC, in Belgium. In 2011, Bernate spent 10 weeks at IMEC in a program hosted by Johns Hopkins’ Institute for NanoBioTechnology and funded by the National Science Foundation.

His doctoral adviser, Drazer, said, the research described in the new journal article eventually led Jorge down the path at IMEC to develop a device that can easily sort whole blood into its components. A provisional patent has been filed for this device.

The research by Bernate and Drazer was funded in part by the National Science Foundation and the National Institutes of Health.

Story by Mary Spiro.

Related links:



German Drazer’s Web page:

Department of Chemical and Biomolecular Engineering:

Shaping up nanoparticles for DNA delivery to cancer cells

Hai-Quan Mao, 2012 Johns Hopkins Nano-Bio Symposium. Photo by Mary Spiro

To treat cancer, scientists and clinicians have to kill cancer cells while minimally harming the healthy tissues surrounding them. However, because cancer cells are derived from healthy cells, targeting only the cancer cells is exceedingly difficult. According to Dr. Hai-Quan Mao of the Johns Hopkins University Department of Materials Science and Engineering, the “key challenge is between point of delivery and point of target tissue” when it comes to delivering cancer therapeutics. Dr. Mao spoke about the difficulties of specifically delivering drugs or genetic material to cancer cells at the 2012 Johns Hopkins University Nano-Bio Symposium. Scientists had originally thought they could create a “magic bullet” to patrol for cancer cells in the body. However, this has not been feasible; only 5 percent of injected nanoparticles reach the targeted tumor using current delivery techniques. Simply put, scientists need to figure out how to inject a treatment into the body and then selectively direct that treatment to cancer cells if the treatments are to work to their full potential.

With this in mind, Dr. Mao and his research team aim to optimize nanoparticle design to improve delivery to tumor cells by making the nanoparticles more stable in the body’s circulatory system. Mao’s group uses custom polymers and DNA scaffolds to create nanoparticles. The DNA serves dual purposes, as a building block for the particles and as a signal for cancer cells to express certain genes (for example, cell suicide genes). By tuning the polarity of the solvent used to fabricate the nanoparticles, the group can control nanoparticle shape, forming spheres, ellipsoids, or long “worms” while leaving everything else about the nanoparticles constant. This allows them to test the effects of nanoparticle size on gene delivery. Interestingly, “worms” appear more stable in the blood stream of mice and are therefore better able to deliver targeted DNA. Studies of this type will allow intelligent nanoparticle design by illuminating the key aspects for efficient tumor targeting.

Currently, Dr. Mao’s group is extending their fabrication methods to deliver other payloads to cancer cells. Small interfering ribonucleic acid (siRNA), which can suppress expression of certain genes, can also be incorporated into nanoparticles. Finally, Mao noted that the “worm”-shaped nanoparticles created by the group look like naturally occurring virus particles, including the Ebola and Marburg viruses. In the future, the group hopes to use their novel polymers and fabrication techniques to see if shape controls virus targeting to specific tissues in the body. This work could have important applications in virus treatment.

Story by Colin Paul, a Ph.D. student in the Department of Chemical and Biomolecular Engineering at Johns Hopkins with interests in microfabrication and cancer metastasis.


Cancer epidemiology: researchers take a broader approach

Elizabeth Platz at 2012 Johns Hopkins Nano-Bio Symposium. Photo by Stephanie Fraley

“Where do cancer data even come from?” This was the question posed to Dr. Elizabeth Platz prior to the 2012 Johns Hopkins University Nano-Bio Symposium. Dr. Platz is the Martin D. Abeloff, MD Scholar in Cancer Prevention and director of the Cancer Epidemiology, Prevention, & Control Training Program at the Johns Hopkins Bloomberg School of Public Health. As a cancer epidemiologist, Platz studies the frequency, distribution, and causes of cancer using data collected by the National Cancer Institute. By looking at these data, epidemiologists hope to understand why cancer occurs and what might be done to prevent it. “Cancer mortality in the US is declining and has been for some time,” Platz said. “The question is why.”

Dr. Platz and other cancer epidemiologists work on answering this “why.” Platz explained that cancer epidemiologists hypothesize why cancer rates may be high in certain segments of the population, follow a cohort of at-risk patients to see if they develop disease, and then try to figure out if some risk factor could be partially responsible for the disease. By identifying risk factors, cancer epidemiologists can influence public policy and promote preventative action.

Increasingly, cancer epidemiologists are working with researchers trying to answer basic science questions. An example of Dr. Platz’s recent interdisciplinary work involves finding tissue-based markers for prostate cancer, which could inform diagnoses and treatment decisions made by clinicians. One potential marker the researchers found is telomere length. Telomeres are repeated units on the ends of all chromosomes. Platz and her team of collaborators at Johns Hopkins showed that variability in tumor cell telomere length gave a 40-times greater risk for recurrence when compared with low telomere length variability. In the future, telomere length may be quantified following removal of a patient’s primary tumor before deciding on the next course of treatment.

Dr. Platz finished her talk by discussing the importance of having scientists in the nanobiotechnology fields work with cancer epidemiologists. Nanobiotechnology could greatly help epidemiologists measure exposure to environmental toxins and handle large amounts of data, allowing the epidemiologists to better make and test hypotheses about why cancer occurs. Future collaborations have the potential to drastically improve cancer care and patient survival rates.

Story by Colin Paul, a Ph.D. student in the Department of Chemical and Biomolecular Engineering at Johns Hopkins with interests in microfabrication and cancer metastasis.


Students talk cancer nanotech at Homewood March 21

Students affiliated with the Center of Cancer Nanotechnology Excellence (CCNE) and the Physical Sciences-Oncology Center (PS-OC) at Johns Hopkins University have organized a spring mini-symposium for March 21, 10 a.m. in the Hackerman Hall Auditorium at the Johns Hopkins University Homewood campus.

The student-run mini-symposiums aim to bring together researchers from across the campus affiliated with the PS-OC and CCNE. Graduate students training in these centers, both administered by Johns Hopkins Institute for NanoBioTechnology, work in various disciplines from physics to engineering to the basic biological sciences but with an emphasis on understanding cancer metastasis and developing methods for cancer diagnosis or therapy.

The invited speaker for the symposium is postdoctoral researcher Megan Ho of Duke University. Ho earned her PhD in mechanical engineering in the Wang lab in 2008. She is currently focused on developing microfluidic devices to investigate and control the fundamental reactions that form nanocomplexes for gene delivery. (10 a.m.)

Student apeakers, who will talk for 15 minutes, include:

  • Jane Chisholm (Justin Hanes lab/Ophthalmology): Cisplatin nanocomplexes for the local treatment of small cell lung cancer (10:20 a.m.)
  • Yunke Song (Jeff Wang Lab/Mechanical Engineering): Single Quantum Dot-Based Multiplexed Point Mutation Detection by Gap Ligase Chain Reaction (10:35 a.m.)
  • Andrew Wong (Peter Searson Lab/Materials Science and Engineering): Intravisation into an artificial blood vessel (10:50 a.m.)
  • Brian Keeley: (Jeff Wang Lab/Mechanical Engineering): Overcoming detection limitations of DNA methylation in plasma and serum of cancer patients through utilization of nanotechnology. (11:05 a.m.)
  • Sebastian Barretto (Sharon Gerecht Lab/Chemical and Biomolecular Engineering): Development of Hydrogel Microfibers to Study Angiogenesis (11:20 a.m.)

View the symposium flyer here. The mini-symposium is free and open to the entire Johns Hopkins University community. No RSVP is required, although seating is limited.

Johns Hopkins Physical Sciences-Oncology Center

Center of Cancer Nanotechnology Excellence