Nanotech checks on transplanted cell survival

Researchers at Johns Hopkins are using nanotechnology to track the survival and location of transplanted cells. The device, based on nanoscale ph sensors and imaging via magnetic resonance, could help improve outcomes from cell replacement therapies used for conditions such as liver disease or type 1 diabetes.

Cartoon showing nanoscale probe used to detect pH change caused by death of transplanted cell. (McMahon/Nature Materials)

Cartoon showing nanoscale probe used to detect pH change caused by death of transplanted cell. (McMahon/Nature Materials)

“This technology has the potential to turn the human body into less of a black box and tell us if transplanted cells are still alive,” says Mike McMahon, Ph.D., an associate professor of radiology at the Johns Hopkins University School of Medicine principal investigator on the study. “That information will be invaluable in fine-tuning therapies.”

Transplanted cells often fall victim to assault from the body’s immune system, which sees the news cells as foreign invaders. Says McMahon,  ”once you put the cells in, you really have no idea how long they survive.”

When cells die there is a change in the acidity nearby. Using this fact, the researchers developed a nanoparticle sensor that could both sense the change in pH and be detected via MRI. The team tested the sensors on mice and found they they were able to track the location of surviving transplanted cells and determine the proportion that had survived.

“It was exciting to see that this works so well in a living body,” says research fellow Kannie Chan, Ph.D., the lead author on the study, which was published in Nature Materials. This should take a lot of the guesswork out of cell transplantation by letting doctors see whether the cells survive, and if not, when they die,” Chan says. “That way they may be able to figure out what’s killing the cells, and how to prevent it.”

Chan works in the laboratory of Jeff Bulte, Ph.D., the director of cellular imaging at Johns Hopkins’ Institute for Cell Engineering. Bulte and McMahon collaborated on the study. Additional authors include Guanshu Liu, Xiaolei Song, Heechul Kim, Tao Yu, Dian R. Arifin, Assaf A. Gilad, Justin Hanes, Piotr Walczak and Peter C. M. van Zijl, all of the Johns Hopkins University School of Medicine. McMahan, Bulte, Gilad, Hanes and van Zijl are all affiliated faculty members of Johns Hopkins Institute for NanoBioTechnology.

Funding for this study was provided by the National Institute of Biomedical Imaging and Bioengineering (grant numbers R01 EB012590, EB015031, EB015032 and EB007825).

Follow this link to read the paper, MRI-detectable pH nanosensors incorporated into hydrogels for in vivo sensing of transplanted-cell viability, in Nature Materials online http://www.nature.com/nmat/journal/vaop/ncurrent/abs/nmat3525.html

FLC event focuses on Maryland technology

Screen Shot 2013-02-04 at 10.59.42 AMMaryland Technology Past, Present and Future is the topic of a day-long symposium, February 28 at the National Electronics Museum hosted by the Federal Laboratory Consortium Mid-Atlantic Region.

The FLC is a national organization chartered by Congress to foster technology transfer from federal research laboratories and field centers, to other federal agencies; state and local government; academia and the private sector. One of the regional consortium’s efforts has been to conduct a series of one-day forums that highlight specific areas of technology and encourage collaboration and partnership development with federal labs.

Registration is $25 and includes refreshments and lunch. Registration deadline is February 15 and can be made online at this link.

The National Electronics Museum is located at 1745 West Nursery Road in Linthicum, Md. The symposium begins with registration at 8:15 a.m. and adjourns at 3:45 p.m.

In addition to the presentations, the day will offer the opportunity to meet scientists from the regions National Labs such as NASA, NIST, NIH and Goddard as well as representatives of local industry. In addition to the FLC Mid-Atlantic Region, participating organizations for this symposium include Johns Hopkins University and TEDCO.

For further information or if you have difficulty accessing the registration site, please contact John Emond at 301-384-2809 or johnlamaremond@aol.com. You may also contact INBT’s director of corporate partnerships, Tom Fekete at 410-516-8891 or tmfeke@jhu.edu.

A flyer and agenda for the event are below:

Maryland Technology Day Agenda

Maryland Technology Day Flyer

INBT engineers coax stem cells to diversify

Growing new blood vessels in the lab is a tough challenge, but a Johns Hopkins engineering team has solved a major stumbling block: how to prod stem cells to become two different types of tissue that are needed to build tiny networks of veins and arteries.

The team’s solution is detailed in an article appearing in the January 2013 print edition of the journal Cardiovascular Research. The article also was published recently in the journal’s online edition. The work is important because networks of new blood vessels, assembled in the lab for transplanting into patients, could be a boon to people whose circulatory systems have been damaged by heart disease, diabetes and other illnesses.

blood-vessel-3-72

Illustration by Maureen Wanjare

“That’s our long-term goal—to give doctors a new tool to treat patients who have problems in the pipelines that carry blood through their bodies,” said Sharon Gerecht, an assistant professor of chemical and biomolecular engineering who led the research team. “Finding out how to steer these stem cells into becoming critical building blocks to make these blood vessel networks is an important step.”

In the new research paper, the Gerecht team focused on vascular smooth muscle cells, which are found within the walls of blood vessels. Two types have been identified: synthetic smooth muscle cells, which migrate through the surrounding tissue, continue to divide and help support the newly formed blood vessels; and contractile smooth muscles cells, which remain in place, stabilize the growth of new blood vessels and help them maintain proper blood pressure.

To produce these smooth muscle cells, Gerecht’s lab has been experimenting with both National Institutes of Health-approved human embryonic stem cells and induced pluripotent stem cells. The induced pluripotent stem cells are adult cells that have been genetically reprogrammed to act like embryonic stem cells. Stem cells are used in this research because they possess the potential to transform into specific types of cells needed by particular organs within the body.

In an earlier study supervised by Gerecht, her team was able to coax stem cells to become a type of tissue that resembled smooth muscle cells but didn’t quite behave properly. In the new experiments, the researchers tried adding various concentrations of growth factor and serum to the previous cells. Growth factor is the “food’ that the cells consume; serum is a liquid component that contains blood cells.

“When we added more of the growth factor and serum, the stem cells turned into synthetic smooth muscle cells,” Gerecht said. “When we provided a much smaller amount of these materials, they became contractile smooth muscles cells.”

This ability to control the type of smooth muscle cells formed in the lab could be critical in developing new blood vessel networks, she said. “When we’re building a pipeline to carry blood, you need the contractile cells to provide structure and stability,” she added. “But in working with very small blood vessels, the migrating synthetic cells can be more useful.”

In cancer, small blood vessels are formed to nourish the growing tumor. The current work could also help researchers understand how blood vessels are stabilized in tumors, which could be useful in the treatment of cancer.

“We still have a lot more research to do before we can build complete new blood vessel networks in the lab,” Gerecht said, “but our progress in controlling the fate of these stem cells appears to be a big step in the right direction.”

In addition to her faculty appointment with Johns Hopkins’ Whiting School of Engineering, Gerecht is affiliated with the university’s Institute for NanoBioTechnology (INBT) and the Johns Hopkins Engineering in Oncology Center.

The lead author of the new Cardiovascular Research paper is Maureen Wanjare, a doctoral student in Gerecht’s lab who is supported both by the INBT, through a National Science Foundation Integrative Graduate Education and Research Traineeship, and by the NIH. Coauthors of the study are Gerecht and Frederick Kuo, who participated in the research as an undergraduate majoring in chemical and biomolecular engineering. The human induced pluripotent stem cells used in the study were provided by Linzhao Cheng, a hematology professor in the Johns Hopkins School of Medicine.

This research was supported by an American Heart Association Scientist Development Grant and NIH grant R01HL107938.

Original press release can be found here.

 

Young, global entrepreneur to speak Dec. 12

The Center for Bioengineering Innovation and Design (CBID) hosts a guest speaker on  Wednesday, December 12, from 12:30 to 2 p.m. in Clark Hall 110 at the Johns Hopkins University Homewood campus.

Jodie Wu, founder/CEO, Global Cycle Solutions

Jodie Wu, founder and CEO of Global Cycle Solutions, will present: “Engineer to Entrepreneur: Starting a business in Africa at Age 22,: in which she will discuss the journey of Global Cycle Solutions, its history, its vision, its operations, and how it became what it is today.

In 2009, Wu at age 22, officially became a full-fledged entrepreneur, packing her bags and moving to Tanzania. Wu will talk about her journey from engineer to entrepreneur and give the insider story of taking her company Global Cycle Solutions, from the classroom to the field.

In addition, Wu will share her fantastic “failures”, the challenges of selling products to the world’s bottom billion, and her vision for the future now that her company has sold over 13,000 products across East Africa and is now operationally break even.

This talk is free and open to the Johns Hopkins community.

 

Molecular culprit linked to breast cancer spread

Johns Hopkins researchers have uncovered a protein “partner” commonly used by breast cancer cells to unlock genes needed for spreading the disease around the body. A report on the discovery, published Nov. 5 on the website of the Proceedings of the National Academy of Sciences, details how some tumors get the tools they need to metastasize.

“We’ve identified a protein that wasn’t known before to be involved in breast cancer progression,” says Gregg Semenza, M.D., Ph.D., the C. Michael Armstrong Professor of Medicine at the Johns Hopkins University School of Medicine and director of the Vascular Program at the university’s Institute for Cell Engineering. “The protein JMJD2C is the key that opens up a whole suite of genes needed for tumors to grow and metastasize, so it represents a potential target for cancer drug development.” Semenza also is associate director of the Johns Hopkins Physical Sciences-Oncology Center.

Semenza and his colleagues made their finding when they traced the activity of HIF-1, a protein known to switch on hundreds of genes involved in development, red blood cell production, and metabolism in normal cells. Previous studies had shown that HIF-1 could also be hijacked to switch on genes needed to make breast tumors more malignant.

Would-be tumor cells face a host of challenges as they make the transition from working with their host to working against it, such as the need to evade the immune system and to produce more cancer cells, explains Weibo Luo, Ph.D., an instructor in the Institute for Cell Engineering and Department of Biological Chemistry who led the project. All of these efforts require switching on the right genes for the job.

To learn more about how HIF-1 works, the researchers tested a range of human proteins to see whether they would interact with HIF-1. They then sifted through the 200 resulting hits, looking for proteins involved in chemical changes to sections of DNA that determine whether or not the genes they contain are available for use. “In order for HIF-1 to switch genes on, they have to be available, but many of the genes HIF-1 activates are normally locked down in mature cells,” explains Luo. “So we thought HIF-1 must have a partner that can do the unlocking.”

That partner turned out to be JMJD2C, Luo says. Delving deeper, the researchers found that HIF-1 switches on the JMJD2C gene, stimulating production of the protein. HIF-1′s presence also enables JMJD2C to bind to DNA at other HIF-1 target genes, and then loosen those DNA sections, enabling more HIF-1 to bind to the same sites and activate the target genes.

To test the implications of their discovery, the research team injected mice with breast cancer cells in which the JMJD2C protein was not produced. Tumors with depleted JMJD2C were much less likely to grow and metastasize to the lungs, confirming the protein’s role in breast cancer progression, says Luo.

“Active HIF proteins have been found in many types of tumors, so the implications of this finding go beyond breast cancer,” says Luo. “JMJD2C is both an important piece of the puzzle of how tumors metastasize, and a potential target for anti-cancer therapy.”

Other authors of the research report are Ryan Chang, Jun Zhong, Ph.D., and Akhilesh Pandey, M.D., Ph.D., all of the Johns Hopkins University School of Medicine.

This work was supported by grants from the National Heart, Lung, and Blood Institute (contracts N01-HV28180 and HHS-N268201000032C), and by funds from the Johns Hopkins Institute for Cell Engineering.

On the Web:

Johns Hopkins Physical Sciences-Oncology Center: http://psoc.inbt.jhu.edu/

Link to article: http://www.pnas.org/content/early/2012/10/31/1217394109.abstract

Semenza lab: http://www.hopkinsmedicine.org/institute_cell_engineering/experts/gregg_semenza.html

Q&A with Semenza: http://www.hopkinsmedicine.org/institute_cell_engineering/experts/meet_scientists/gregg_semenza.html

Original press release by Shawna WilliamsCatherine Kolf and Vanessa McMains

 

 

DNA folded into shapes offers alternative gene delivery vehicle

DNA molecules (light green) packaged into nanoparticles of different shapes using a polymer with two different segments. Cartoon illustrations created by Wei Qu, Northwestern University and Martin Rietveld, Johns Hopkins /INBT. Microscopic images created by Xuan Jiang, Johns Hopkins University.

Using snippets of DNA as building blocks to create nanoscale rods, worms and spheres, researchers at Johns Hopkins and Northwestern universities have devised a means of delivering gene therapy that avoids some of the undesirable aspects of using viruses to deliver genes to treat disease. The shape and size of the DNA-based nanoparticle also affected how well the genes were delivered.

Worm shapes, for example, were particularly effective.

“The worm-shaped particles resulted in 1,600 times more gene expression in the liver cells than the other shapes,” said Hai-Quan Mao, an associate professor ofmaterials science and engineering in Johns Hopkins’ Whiting School of Engineering. “This means that producing nanoparticles in this particular shape could be the more efficient way to deliver gene therapy to these cells.”

This study was published in the Oct. 12 online edition of Advanced Materials.

Initial funding for the research came from a seed grant provided by the Johns Hopkins Institute for NanoBioTechnology, of which Mao is an affiliate. The Johns Hopkins-Northwestern partnership research was supported by a National Institutes of Health grant.

Read the entire Johns Hopkins press release by Phil Sneiderman (JHU) and Megan Fellman (Northwestern) here.

 

 

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.