In vivo visualization of angiogenesis during wound healing featured on journal cover

Laser speckle contrast images showing (l-r) sequential images of the in vivo blood flow changes that occur on days 0, 3, 5, 7, 10 and 12 after wound creation.

Innovative ways of imaging wound healing can reveal much about blood vessel remodeling and blood flow following an injury. Researchers in the Russell H. Morgan Department of Radiology and Radiological Science and Department of Biomedical Engineering at the Johns Hopkins University School of Medicine have developed a method for using laser speckle contrast imaging (LSCI) to elucidate the changes that occur in the microvasculature over time as a wound heals. Researchers in the laboratory of Arvind P. Pathak have visualized the wound healing process in a mouse ear model by capturing images of angiogenesis—or the development of new blood vessels—over a 12-day period.

“LSCI is a powerful tool for observing the architecture and remodeling of microvasculature as well as the hemodynamic changes (blood flow) during angiogenesis,” said Pathak, an assistant professor of radiology and oncology and principal investigator on the study. “Being able to watch this process occur in a living animal helps us better understand the role of the vasculature during various phases of the wound healing process.”

Stunning images obtained from their experiments were featured on the cover of the March issue of the journal Angiogenesis. The LSCI images shown on the cover from left to right are sequential images of the in vivo blood flow changes that occur on days 0, 3, 5, 7, 10 and 12 after wound creation. The “hotter” colors indicate higher blood flow. The background image is a grayscale LSCI image from an uninjured mouse ear.

Wound healing typically proceeds in three phases, Pathak explained: inflammation (which initiates the immune response and recruits immune cells and molecules to the injury), proliferation (the formation of new blood vessels and epithelium) and remodeling (which removes the vascular scar created during blood vessel formation). LSCI is ideal for imaging the progression of each phase because it can monitor in vivo changes in microvascular architecture and hemodynamics at the same time, he said.

LSCI images are created when tissue illuminated by a laser is photographed through a small aperture, explained Pathak. “The resulting images exhibit a random interference pattern, also called a ‘speckle’ pattern. In blood vessels, this speckle pattern shifts due to the orderly motion of red blood cells, causing a blur over the exposure time of the camera. The degree of blurring in the LSCI image is proportional to the velocity of blood in the vessels and constitutes the biophysical basis of LSCI. Therefore, LSCI can distinguish blood vessels in tissue without any fluorescent dye or contrast agent.”

In this way, Pathak added, LSCI is capable of “wide area mapping” of the tissue, allowing us to measure not only the length and perfusion of blood vessels but their tortuosity (twistiness) and the overall flow of blood to the wound site as healing progresses.

In addition to angiogenesis research, the imaging method has practical applications in drug testing, Pathak said. “Using LSCI alongside a drug study would provide better insight into the efficacy of drug delivery and therapeutic outcome,” he said.

The lead author of the paper was Abhishek Rege, a graduate student in biomedical engineering co-mentored by Pathak and Nitish V. Thakor, professor of biomedical engineering in whose neuroengineering laboratory LSCI was developed. Kevin Rhie, a research technician in Pathak’s laboratory was the other author on this study.

This work was supported jointly by a Johns Hopkins Institute for NanoBiotechnology (INBT) Junior Faculty Pilot Award to Pathak, and grants from the National Institute of Aging and the Department of Health and Human Services to Thakor.

Story by Mary Spiro

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: http://microfluidics.jhu.edu/

Department of Chemical and Biomolecular Engineering: http://www.jhu.edu/chembe/

INBT professional development seminar topics announced

Every summer, Johns Hopkins Institute for NanoBioTechnology hosts a series of free professional development seminars for the Hopkins community. Seminars will be held from 10:45 a.m. to noon on the second and fourth Wednesdays in June and July in Shaffer 3 (the basement auditorium). Dates and topics are as follows:

  • June 13:  How to promote yourself and the benefits of networking with Tom Fekete, INBT’s director of Corporate Partnerships.
  • June 27:  Why should you consider grad school and how do you prepare? The speaker is Christine Kavanaugh, Assistant Director of Graduate Admissions, Communications and Enrollment for Johns Hopkins University.
  • July 11: I got my PhD, now what?  This will be a panel discussion about various career pathways post graduate school, including  entrepreneurship and working in academia or the government. Panel participants will be Shyam Khatau, PhD (Chemical and Biomolecular Engineering JHU); Stephen Diegelmann, PhD (Chemistry, JHU now working at Case Western Reserve University); and Nicole Moore, ScD (Program Manager in the Office of Physical Sciences-Oncology at NIH/ NCI).
  • July 25: INBT Student Film Festival. This seminar will premiere the films made by students in the Science Communications for Scientists and Engineers course taught by Mary Spiro, INBT’s science writer.

 

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.

 

Four students honored at INBT research symposium

Spyros Stamatelos with INBT director Peter Searson. Photo by Mary Spiro

Four students were honored for their research efforts at Johns Hopkins Institute for NanoBioTechnology’s sixth annual symposium. A poster session with more than 75 research posters from every division of the university was held in the afternoon and four posters were selected for top honors.

A poster by Yu-Ja Huang, Justin Samorajski, Rachel Kreimer, Denis Wirtz and Peter Searson won first prize, and first author Huang was awarded the $200 gift card from Best Buy. Their poster was entitleThe Influence of Electric Field and Confinement on U-87 Glioblastoma Cells.

Jack Andraka describing his research at the INBT poster session. Photo by Mary Spiro

Taking second place was Anirudha Sing, Jianan Zhan and Jennifer Elisseeff with the poster Directed Stem Cell Differentiation Using PEG-alpha CD-derived biomaterials. First author Singh claimed the $100 Best Buy card.

A $50 Best Buy card was presented to Spyros Stamatelos who was first author with Eugene Kim, Arvind Pathak and Aleksander Popel on the poster Characterization of the Heterogeneity of Tumor Vasculature using Hemodynamic Modeling and High Resolution Imaging Implications for Drug Delivery.

Honorable mention was given to Jack Andraka, a high school research intern in the lab of Anirban Maitra who worked with Venugopal Chenna. Andraka’s poster, A Novel Paper Sensor for the Detection of Pancreatic Cancer, helped him win a free book from Springer.

The event was held  at the Johns Hopkins medical campus in the Owens Auditorium on May 4 with six faculty expert speakers and approximately 400 people in attendance.

Baby crystal discovery big step for nanoscience

How small can a chemical compound be and still retain the properties of that same compound in bulk? With computer models and laboratory experiments, researchers at Johns Hopkins University, collaborating with those at McNeese State University in Lake Charles, LA, and the University of Konstanz in Germany, have determined the smallest crystal configuration, or as they call it, a “baby crystal,” of lead sulfide.

Predicted dimensions of nano-blocks achieved by growing individual (PbS)32 baby crystals. STM images confirmed these dimensions. (Illustration courtesy Bowen Lab)

The team first determined the structure theoretically with computer modeling. They then proved their model experimentally in the laboratory by carefully depositing clusters of (PbS)32 onto a graphite surface, where the clusters could migrate together into larger nanoscale units.

“By using scanning tunneling microscope (STM) images to measure the dimensions of the resultant lead sulfide nano-blocks, we confirmed that (PbS)32 baby crystals had indeed stacked together as predicted by theory,” said Kit Bowen Jr., the E. Emmet Reid Professor in the Department of Chemistry at Johns Hopkins. Bowen worked on the project with, Howard Fairbrother, also a professor of chemistry. Both are affiliated faculty members of the Institute for NanoBioTechnology.

Bowen explained that the baby crystal needed just 32 units of lead sulfide to “exhibit the same structural coordination properties” of the same material at macroscale. Nanoblocks this small would have photovoltaic (solar power) applications.

“Determining the size of nano and sub-nano scale assemblies of atoms or molecules at which they first take-on recognizable properties of the same substance in the macroscopic world is an important goal in nanoscience,” Bowen said.

Their research can be found in the Journal of Chemical Physics and The Virtual Journal of Nanoscale Science & Technology. A Department of Energy grant funded this research.

 The Virtual Journal of Science & Technology

Bowen Lab

 

INBT obtains funding for engineering and science missions

Johns Hopkins students helped develop a bicycle-powered grain mill in Tanzania.

Engineering Missions for Graduate Student Education and Local Innovation

Applications are now being accepted for Global Engineering Innovation projects designed to give Johns Hopkins’ graduate students and select undergraduates an opportunity to investigate and tackle engineering challenges in the developing world. Undergraduate and graduate opportunities are available. Application deadline is April 5, 2013.

An information session on the Global Engineering Innovation program will be held on April 12  at 6 p.m. in  room G40 (ground floor conference room) in the New Engineering Building.

Johns Hopkins Institute for NanoBioTechnology has obtained funding to support three engineering mission teams composed of two to four students at a variety of international host sites. Teams will be mentored by an engineering faculty and a faculty member from the host site. Budgets, time lines and project plans will be developed by the team members with assistance by the host site faculty member.

To be eligible to apply, undergraduate and graduate students should be science or engineering majors (other majors will be considered if a fit is evident based on application material). Teams can be predefined by the students prior to applying but each team member must submit all application material. We will attempt to keep predefined teams together but the final decision will be made by the coordination committee (we will add or remove members if we feel a better team composition can be made).

To apply for this unique opportunity, send the following items to Ashanti Edwards at ashanti@jhu.edu.

  • Your resume including any outreach experience (domestic or international) and any foreign language capability (not required)
  • A brief (300 words max.) statement of your interest in Global Engineering Innovation
  • The name and contact information of at least one referee, preferably your faculty research advisor (or academic advisor for undergraduate students)

After teams, mentors and challenges are defined, the team or team leader will travel to the site to further evaluate challenge and design constraints. After return to Baltimore, the teams will meet to further research the challenge and brainstorm potential solutions. The JHU School for Advanced International Studies (SAIS) will be consulted so that students will be aware of the social and political atmosphere that may impact utilization and potential distribution of the engineering solutions. By the end of the first year, the students will have designed a working prototype. The teams will then travel to the Global Site with their working prototype to test solution feasibility and modify as needed. If successful, potential avenues of translation will be investigated with advisory board members with relevant experience.

 

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

It’s a small world: Micro/nanotechnology in regenerative medicine and cancer

Sageeta Bhatia

Nanotechnology, regenerative medicine and cancer will be the topic of a special biomedical engineering seminar on March 6 at 3 p.m. in the Darner Conference Room, Ross Building, Room G007 at the Johns Hopkins School of Medicine. Speaker Sangeeta Bhatia, MD, PhD, director, of the Laboratory for Multiscale Regenerative Technologies at Massachusetts Institute of Technology will present “It’s a small world: Micro/Nanotechnology in Regenerative Medicine and Cancer. ” She will discuss the role of micro and nanotechnology for mimicking, monitoring and perturbing the tissue microenvironment.

“I will present our work on reconstructing normal liver microenvironments using microtechnology, biomaterials and induced pluripotent stem cells as well as our work on normalizing diseased cancer microenvironments using both inorganic and organic nano materials,” Bhatia noted in an announcement.  Bhatia is a professor of Health Sciences and Technology and professor of Electrical Engineering and Computer Science at MIT.

The talk is hosted by associate professor of Materials Science and Engineering and affiliated faculty member of the Institute for NanoBioTechnology Hai-Quan Mao. The event is free and open to the Johns Hopkins Community. Refreshments will be served.