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).


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


Hruban discusses challenges in pathology at INBT symposium

Dr. Ralph Hruban of the Johns Hopkins School of Medicine at the INBT annual NanoBio Symposium. Photo by Mary Spiro

Pancreatic cancer is well known as one of the most malicious types of cancers. Seventy-five percent of people lose their battle with pancreatic cancer within a year of diagnosis and only 5 percent survive beyond five years.

“There is opportunity for nanotechnology to have an impact,” said Dr. Hruban as he highlighted the many challenges in improving detection and treatment of pancreatic cancers during his talk at the annual Nano-Bio Symposium hosted by Johns Hopkins Institute for NanoBioTechnology on May 4.

Pathologists have been able to determine many histological changes in cancerous pancreatic ducts and also many of the related genetic changes. The challenge is to translate these discoveries in pathology into novel diagnostic tools.

“Early detection is the best hope in fighting cancer,” said Hruban. Nanotechnology could allow for visualization of genetic changes and changes in protein expression in pancreatic lesions which would help in earlier detection.

Treatment of these pancreatic lesions could be better handled with more robust imaging and staining techniques. Thousands of CAT scans are taken at Johns Hopkins hospital every year and doctors began screening all of these CAT scans performed at the hospital to identify pancreatic cysts.

Even with the cysts identified, there is no way to tell if the cyst is benign or malignant without surgery. Hruban gave as an example a female patient that was pregnant who was identified with a pancreatic cyst that turned out to be benign. For months after, the patient had a variety of health problems due to the surgery.

Hruban gave an old folk rhyme about coral snakes as an analogy, “Red on yellow, kill a fellow. Red on black, friend of Jack.” Nanotechnology could provide a means of visualizing which cysts are harmful and prevent patients from having unnecessary surgeries.

Story by Gregg Duncan, a Ph.D. student in the Department of Chemical and Biomolecular Engineering with interests in biomaterials and drug delivery.

Engineered hydrogel helps grow new, scar-free skin

In early testing, this hydrogel, developed by Johns Hopkins researchers, helped improve healing in third-degree burns. Photo by Will Kirk/

Johns Hopkins researchers have developed a jelly-like material and wound treatment method that, in early experiments on skin damaged by severe burns, appeared to regenerate healthy, scar-free tissue.

In the Dec. 12-16 online Early Edition of Proceedings of the National Academy of Sciences, the researchers reported their promising results from mouse tissue tests. The new treatment has not yet been tested on human patients. But the researchers say the procedure, which promotes the formation of new blood vessels and skin, including hair follicles, could lead to greatly improved healing for injured soldiers, home fire victims and other people with third-degree burns.

The treatment involved a simple wound dressing that included a specially designed hydrogel—a water-based, three-dimensional framework of polymers. This material was developed by researchers at Johns Hopkins’ Whiting School of Engineering, working with clinicians at the Johns Hopkins Bayview Medical Center Burn Center and the Department of Pathology at the university’s School of Medicine.

Third-degree burns typically destroy the top layers of skin down to the muscle. They require complex medical care and leave behind ugly scarring. But in the journal article, the Johns Hopkins team reported that their hydrogel method yielded better results. “This treatment promoted the development of new blood vessels and the regeneration of complex layers of skin, including hair follicles and the glands that produce skin oil,” said Sharon Gerecht, an assistant professor of chemical and biomolecular engineering who was principal investigator on the study.

Guoming Sun, left, a postdoctoral fellow, and Sharon Gerecht, an assistant professor of chemical and biomolecular engineering, helped develop a hydrogel that improved burn healing in early experiments. Photo by Will Kirk/

Gerecht said the hydrogel could form the basis of an inexpensive burn wound treatment that works better than currently available clinical therapies, adding that it would be easy to manufacture on a large scale. Gerecht suggested that because the hydrogel contains no drugs or biological components to make it work, the Food and Drug Administration would most likely classify it as a device. Further animal testing is planned before trials on human patients begin. But Gerecht said, “It could be approved for clinical use after just a few years of testing.”

John Harmon, a professor of surgery at the Johns Hopkins School of Medicine and director of surgical research at Bayview, described the mouse study results as “absolutely remarkable. We got complete skin regeneration, which never happens in typical burn wound treatment.”

If the treatment succeeds in human patients, it could address a serious form of injury. Harmon, a coauthor of the PNAS journal article, pointed out that 100,000 third-degree burns are treated in U. S. burn centers like Bayview every year. A burn wound dressing using the new hydrogel could have enormous potential for use in applications beyond common burns, including treatment of diabetic patients with foot ulcers, Harmon said.

Guoming Sun, Gerecht’s Maryland Stem Cell Research Postdoctoral Fellow and lead author on the paper, has been working with these hydrogels for the last three years, developing ways to improve the growth of blood vessels, a process called angiogenesis. “Our goal was to induce the growth of functional new blood vessels within the hydrogel to treat wounds and ischemic disease, which reduces blood flow to organs like the heart,” Sun said. “These tests on burn injuries just proved its potential.”

Gerecht says the hydrogel is constructed in such a way that it allows tissue regeneration and blood vessel formation to occur very quickly. “Inflammatory cells are able to easily penetrate and degrade the hydrogel, enabling blood vessels to fill in and support wound healing and the growth of new tissue,” she said. For burns, the faster this process occurs, Gerecht added, the less there is a chance for scarring.

Originally, her team intended to load the gel with stem cells and infuse it with growth factors to trigger and direct the tissue development. Instead, they tested the gel alone. “We were surprised to see such complete regeneration in the absence of any added biological signals,” Gerecht said.

Sun added, “Complete skin regeneration is desired for various wound injuries. With further fine-tuning of these kinds of biomaterial frameworks, we may restore normal skin structures for other injuries such as skin ulcers.”

Gerecht and Harmon say they don’t fully understand how the hydrogel dressing is working. After it is applied, the tissue progresses through the various stages of wound repair, Gerecht said. After 21 days, the gel has been harmlessly absorbed, and the tissue continues to return to the appearance of normal skin.

The hydrogel is mainly made of water with dissolved dextran—a polysaccharide (sugar molecule chains). “It also could be that the physical structure of the hydrogel guides the repair,” Gerecht said. Harmon speculates that the hydrogel may recruit circulating bone marrow stem cells in the bloodstream. Stem cells are special cells that can grow into practically any sort of tissue if provided with the right chemical cue. “It’s possible the gel is somehow signaling the stem cells to become new skin and blood vessels,” Harmon said.

Additional co-authors of the study included Charles Steenbergen, a professor in the Department of Pathology; Karen Fox-Talbot, a senior research specialist from the Johns Hopkins School of Medicine; and physician researchers Xianjie Zhang, Raul Sebastian and Maura Reinblatt from the Department of Surgery and Hendrix Burn and Wound Lab. From the Whiting School’s Department of Chemical and Biomolecular Engineering, other co-authors were doctoral students Yu-I (Tom) Shen and Laura Dickinson, who is a Johns Hopkins Institute for NanoBioTechnology (INBT) National Science Foundation IGERT fellow. Gerecht is an affiliated faculty member of INBT.

The work was funded in part by the Maryland Stem Cell Research Fund Exploratory Grant and Postdoctoral Fellowship and the National Institutes of Health.

The Johns Hopkins Technology Transfer staff has filed a provisional patent application to protect the intellectual property involved in this project.

Related links:

Sharon Gerecht’s Lab

Johns Hopkins Burn Center

Johns Hopkins Institute for NanoBioTechnology


Story by Mary Spiro

Hopkins faculty to present at American Society for NanoMedicine meeting

© Liudmila Gridina |

The American Society for NanoMedicine (ASNM) will hold its third annual meeting November 9 -11 at the Universities at Shady Grove Conference Center in Gaithersburg, Md. This year ASNM has worked closely with the Cancer Imaging Program, National Cancer Institute, and National Institutes of Health to create a conference with a special focus on nano-enabeled cancer diagnostics and therapies, and the synergy of the combination of nano-improved imaging modalities and targeted delivery.

The program also focuses on updates on the newest Food and Drug Administration, nanotoxicity, nanoparticle characterization, nanoinformatics, nano-ontology, results of the latest translational research and clinical trials in nanomedicine, and funding initiatives. This year’s keynote speaker is Roger Tsien, 2008 Nobel Prize Laureate. Numerous other speakers and breakout sessions are planned for the three day event. Two speakers affiliated with Johns Hopkins include Justin Hanes and Dmitri Artemov. Hanes is a professor of nanomedicine in the department of ophthalmology at the Johns Hopkins School of Medicine. Artemov is an associate professor of radiology/magnetic resonance imaging research, also at the School of Medicine.

The deadline for the poster abstracts is October 1. The top four posters submitted by young (pre and post doctoral) investigators will be selected to give a short 10-minute (eight slides) oral presentation on November 11.

ASNM describes itself as a “a non-profit, open, democratic and transparent professional society…focus(ing) on cutting-edge research in nanomedicine and moving towards realizing the potential of nanomedicine for diagnosis, treatment, and prevention of disease.” More information about the ASNM can be found on the Society’s official website.



Summer scholars celebrate first high school graduates

Charles Booth and his mentor Yulia Artemenko at the 2011 Boys Hope poster session. Photo: Mary Spiro

To encourage promising high school students to pursue careers in academia and research, Johns Hopkins Institute for NanoBioTechnology and the Johns Hopkins School of Medicine welcome scholars from Baltimore’s Boys Hope Girls Hope (BHGH) to work in university laboratories. From June through August each summer for the past three years, high school students have worked alongside scientists in Johns Hopkins University laboratories producing raw data that supports the research goals of their mentors.

This summer, the university welcomed four BHGH scholars and, at the conclusion of the session, the scholars presented their findings to faculty, students, staff, and members of their families during a poster session held, August 12. The program also celebrated its first two high school graduates.

Matthew Green-Hill has been in the BHGH/INBT program for three summers. He graduated this spring from Archbishop Curley High School and was accepted to The College of William and Mary where he plans to study political science. He worked in the lab of assistant professor Sean Taverna in the department of pharmacology and molecular sciences. Along with his mentor PhD student Tonya Gilbert, Green-Hill presented “Cloning Yng1 to Identify Novel Histone Modification Binding Motifs that may affect Gene Expression” at the poster session.

Dwayne Thomas II worked in the cell biology laboratory of associate professor Douglas Robinson. He and his mentor, PhD student Hoku West-Foyle, conducted research that was presented in the poster “Dictyostelium discoideum myosin-ll, a modular motor.” Thomas has participated in the summer research program for two summers. He graduated from Loyola Blakefield in May and will attend Loyola University Maryland in the fall as a biology/pre-med major.

Working in the biological chemistry laboratory of professor Craig Montell, Durrell Igwe was mentored by postdoctoral fellow Marquis Walker and presented the poster “Reduced Immune Response in Drosophila Lysosomal Storage Disease Model.” This is also Igwe’s second year in the program, and he will graduate from Archbishop Curley High School in the spring of 2012.

One of the newest BHGH scholars is Charles Booth, who worked with postdoctoral fellow Yulia Artemenko in the cell biology lab of professor Peter Devreotes. He presented the poster “Analysis of the Functional Redundancy Between Dictyostelium KrsB and Its Mammalian Homolog Mstl.” Booth attends Calvert Hall and will be a junior this fall.

The BHGH program is geared toward students with academic potential but who lack the resources or stability to achieve their full potential. Some of those who have participated in the program may have at one time missed weeks of school in the past. Others have even been homeless. Students voluntarily apply to the nonprofit program to access services such as a stable home, tutoring, and counseling. Scholars have the opportunity to live together in an adult-supervised house in Baltimore and attend local private schools. Both boys and girls participate in the program and next year, Robinson said he hopes Hopkins will attract some of the young women interested in science and medicine to work in sponsored laboratories.

Additional photos on our Facebook Page.

Boys Hope Girls Hope Baltimore

Story by Mary Spiro






Hopkins Imaging Initiative to host first annual conference

The Johns Hopkins University Imaging Initiative will host the first annual Imaging Conference, October 6, 2011 at the Turner Auditorium on the medical campus. The conference features afternoon lectures from various Hopkins faculty followed by a research poster session and happy hour. Anyone interested in imaging is welcome to attend.

Speakers include Elliot McVeigh, director of the Department of Biomedical Engineering; Elliot Fishman, MD, director of diagnostic imaging at body CT at Johns Hopkins Hospital; Jerry Prince, the William B. Kouwenhoven Professor of Electrical and Computer Engineering at the Whiting School of Engineering; Xingde Li, associate professor of biomedical engineering and head of the Laboratory of Biophotonics Imaging and Therapy at the Whiting School; Peter van Zijl, professor of radiology at the school of medicine and director of the F.M. Kirby Research Center for Functional Brain Imaging; and several others to be announced.

Abstracts will be accepted until Sept 6 and conference registration will be accepted until October 1. For complete information about this event and to register, go to





‘Just add water’ to activate freeze-dried brain cancer fighting nanoparticles

A fluorescence micrograph showing brain cancer cells producing a green fluorescent protein. DNA encoded to produce the protein was delivered to the cancer cells by new freeze-dried nanoparticles produced by Johns Hopkins biomedical engineers. Image: Stephany Tzeng/JHU

Biomedical engineers and clinicians at Johns Hopkins University have developed freeze-dried nanoparticles made of a shelf-stable polymer that only need the addition of water to activate their cancer-fighting gene therapy capabilities.

Principal investigator Jordan Green, assistant professor in the department of Biomedical Engineering at the Johns Hopkins School of Medicine, led the team that fabricated the polymer-based particles measuring 80 to 150 nanometers in diameter. Each particle, which is about the size of a virus, has the ability to carry a genetic cocktail designed to produce brain cancer cell-destroying molecules. After manufacture, the nanoparticles can be stored for up to 90 days before use. In principle, cancer therapies based on this technology could lead to a convenient commercial product that clinicians simply activate with water before injection into brain cancer tumor sites.

Because this method avoids the common, unpleasant side effects of traditional chemotherapy, “nanoparticle-based gene therapy has the potential to be both safer and more effective than conventional chemical therapies for the treatment of cancer,” Green said. But, he added current gene therapy nanoparticle preparations are just not practical for clinical use.

“A challenge in the field is that most non-viral gene therapy methods have very low efficacy. Another challenge with biodegradable nanoparticles, like the ones used here is that particle preparation typically takes multiple time-sensitive steps.” Green said. “Delay with formulation results in polymer degradation, and there can be variability between batches. Although this is a simple procedure for lab experiments, a clinician who wishes to use these particles during neurosurgery will face factors that would make the results unpredictable.”

In contrast, the nanoparticles developed by the Green lab are a freeze-dried, or “lyophilized,” formulation. “A clinician would simply add water, and it is ready to inject,” Green said. Green thinks this freeze-dried gene-delivery nanoparticle could be easily manufactured on a large scale.

Co-investigator Alfredo Quinones-Hinojosa, a Johns Hopkins Hospital clinician-scientist and associate professor in the departments of Neurosurgery and Oncology at the Johns Hopkins School of Medicine, said he could imagine particles based on this technology being used in conjunction with, and even instead of, brain surgery. “I envision that one day, as we understand the etiology and progression of brain cancer, we will be able to use these nanoparticles even before doing surgery,” Quinones said. “How nice would that be? Imagine avoiding brain surgery all together!”

Currently, patients with glioblastoma, or brain cancer, only have a median survival of about 14 months, Green said. “Methods other than the traditional chemotherapy drugs and radiation—or in combination with them—may improve prognosis,” he said.

Gene therapy approaches could also be personalized, Green said. “Because gene therapy can take advantage of many naturally-existing pathways and can be targeted to the cancer type of choice through nanoparticle design and transcriptional control, several levels of treatment specificity could be provided,” Green said.

The nanoparticles self-assemble from a polymer structural unit, so fabrication is fairly simple, said Green. Finding the right polymer to use, however, proved to be a challenge. Lead author Stephany Tzeng, a PhD student in biomedical engineering in Green’s lab screened an assortment of formulations from a “polymer library” before hitting on a winning combination.

“One challenge with a polymer library approach is that there are many polymers to be synthesized and nanoparticle formulations to be tested. Another challenge is designing the experiments to find out why the lead formulation works so well compared to other similar polymers and to commercially available reagents,” Green said.

Tzeng settled on a particular formulation of poly(beta-amino ester)s specifically attracted to glioblastoma (GB) cells and to brain tumor stem cells (BTSC), the cells responsible for tumor growth and spread. “Poly(beta-amino ester) nanoparticles are generally able to transfect many types of cells, but some are more specific to GBs and BTSCs,” Tzeng said.

The nanoparticles work like a virus, co-opting the cell’s own protein-making machinery, but in this case, to produce a reporter gene (used to delineate a tumor’s location) or new cancer fighting molecule. “It is possible that glioblastoma-derived cells, especially brain tumor stem cells, are more susceptible to our gene delivery approach because they divide much faster,” Tzeng added.

Not only are the particles convenient to use, the team discovered that dividing cells continued to make the new protein for as long as six weeks after application. “The gene expression peaked within a few days, which would correspond to a large initial dose of a therapeutic protein,” said Green. “The fact that gene expression can continue at a low level for a long time following injection could potentially cause a sustained, local delivery of the therapeutic protein without requiring subsequent injection or administration. The cells themselves would act as a ‘factory’ for the drug.”

Once the nanoparticles release their DNA cargo, Tzeng said the polymer quickly degrades in water, usually within days. “From there, we believe the degradation products are processed and excreted with other cellular waste products,” Tzeng said.

Members of the Green Lab are now working on identifying the intracellular mechanism responsible for facilitating cell-specific delivery. “We also plan to build additional levels of targeting into this system to make it even more specific. This includes modifying the nanoparticles with ligands to specifically bind to glioblastoma cells, making the DNA cargo able to be expressed only in GB cells, and using a DNA sequence whose product is only effective in GB cells.”

So far, the team has only successfully transfected brain tumor stem cells using these nanoparticles in a plastic dish. The next step is to test the particle in animal models.

“We hope to begin tests in vivo in the near future by implanting brain tumor stem cells into a mouse and injecting particles. We also hope to begin using functional genes that would kill cancer cells in addition to the fluorescent proteins that serve only as a marker,” Tzeng said.

Other authors who contributed to this work are Hugo Guerrero-Cázares, postdoctoral fellow in Neurosurgery and Oncology, and Joel Sunshine, an M.D.-Ph.D. candidate, and Elliott Martinez, an undergraduate leadership alliance summer student, both from Biomedical Engineering. Funding for this work came from the National Institutes of Health, Howard Hughes Medical Institute, the Robert Wood Johnson Foundation and a pilot-grant from Johns Hopkins Institute for NanoBioTechnology (INBT). Green is an affiliated faculty member of INBT. The research will be published in Issue #23 (August 2011) of the journal Biomaterials and is currently available online.

Freeze-dried gene therapy system avoids virus, complications

Story by Mary Spiro


Mini symposium highlights Johns Hopkins student work in cancer nanotechnology

Maureen Wanjara and Laura Dickinson, Johns Hopkins INBT predoctoral students from Sharon Gerecht’s lab (Photo: Marty Katz)

Johns Hopkins Institute for NanoBioTechnology will host a half-day mini-symposium on Wednesday, March 23 to showcase current research from students affiliated with its Engineering in Oncology Center and Center of Cancer Nanotechnology Excellence. Talks begin at 9 a.m. in Hackerman Hall Auditorium (Room B17) and will conclude by noon.

Students speaking include from the Whiting School of Engineering, predoctoral fellows in Chemical and Biomolecular Engineering Stephanie Fraley, Laura Dickinson, and Craig Schneider; and postdoctoral fellows Christopher Hale, Jaeho Park, and Eric Balzer. Speaking from Biomedical Engineering will be predoctoral fellow Yi Zhang and undergradute Kelvin Liu; and in Mechanical Engineering postdoctoral fellow Sam Walcott. Also giving presentations are predoctoral fellow Dipankar Pramanik in Pathology at the Johns Hopkins School of Medicine and John Fini, director of intellectual property for the Homewood campus schools.

Johns Hopkins Engineering in Oncology Center, a Physical Sciences-Oncology Center (PS-OC) funded by a grant from the National Cancer Institute, aims to unravel the physical underpinnings involved in the growth and spread of cancer. Johns Hopkins Center of Cancer Nanotechnology Excellence, also funded by a grant from the NCI, aims to use a multidisciplinary approach to develop nanotechnology-based tools and strategies for comprehensive cancer diagnosis and therapy and to translate those tools to the marketplace.

There is no need to RSVP for the mini-symposium. All Johns Hopkins students, faculty and staff are welcome to attend.

John Hopkins Institute for NanoBioTechnology

Engineering in Oncology Center

Center of Cancer Nanotechnology Excellence

Former nanobio summer intern featured in med school newsletter

Obafemi Ifelowo (Photo:MSpiro)

One of Johns Hopkins Institute for NanoBioTechnology’s 2010 summer research interns –Obafemi Ifelowo, a senior molecular biology, biochemistry and bioinformatics major at Towson University– was featured in a recent issue of the Johns Hopkins School of Medicine Science Newsletter. Ifelowo worked in the biomedical engineering laboratory of affiliated faculty member Jordan Green. Read more.

INBT’s summer nanobio internship is a Research Experience for Undergraduates (REU) program funded by the National Science Foundation. The Institute supported 16 students during the summer of 2010 for 10 weeks of research in laboratories across The Johns Hopkins University campuses.  Learn more about INBT’s summer nanobio REU program  here.