Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Injecting iron supplement lets Stanford scientists track transplanted stem cells

12.07.2013
A new, noninvasive technique for tracking stem cells after transplantation — developed by a cross-disciplinary team of radiologists, chemists, statisticians and materials scientists at the Stanford University School of Medicine — could help surgeons determine whether a procedure to repair injured or worn-out knees is successful.

The technique, described in a study to be published online July 12 in Radiology, relies on an imaging agent already approved by the U.S. Food and Drug Administration for an entirely different purpose: anemia treatment. Although this study used rodents, the approach is likely to be adapted for use in humans this fall as part of a clinical trial in which mesenchymal stem cells will be delivered to the site of patients' knee injuries. Mesenchymal stem cells are capable of differentiating into bone and cartilage, as well as muscle, fat and tendon, but not into the other cell types that populate the body.

Every year, arthritis accounts for 44 million outpatient visits and 700,000 knee-replacement procedures. But the early repair of cartilage defects in young patients may prevent further deterioration of the joint and the need for knee replacement later in life, said the study's senior author, Heike Daldrup-Link, MD, PhD, an associate professor of radiology and clinician who splits her time between research and treating pediatric patients.

Mesenchymal stem cells have been used with some success in cartilage-repair procedures. "These cells can be easily derived from bone marrow of patients who are going to undergo the knee-repair procedure," said Daldrup-Link, a member of the Molecular Imaging Program at Stanford. "And they can differentiate into the real-life tissues that compose our joints. But here, too, things can go wrong. The newly transferred cells might fail to engraft, or die. They might migrate away. They could develop into tissues other than cartilage, most commonly fibrous scar tissue."

Relatively few transplanted cells go the distance. The ability to monitor the cells' engraftment after they are deposited at a patient's knee-injury site is therefore essential. With the new technique, magnetic resonance imaging can visualize stem cells for several weeks after they have been implanted, giving orthopaedic surgeons a better sense of whether the transplantation was successful.

Until now, the only ways of labeling mesenchymal stem cells so that they could be noninvasively imaged have required their manipulation in the laboratory. Upon extraction, the delicate cells have to be given to lab personnel, incubated with contrast agents, spun in a centrifuge and washed and returned to the surgeons, who then transplant the cells into a patient.

The new technique involves labeling the cells before extraction, while they reside in the donor's bone marrow. For the study, lead authors Aman Khurana, MD, a postdoctoral scholar, and Fanny Chapelin, a research associate, injected ferumoxytol, an FDA-licensed anemia treatment composed of iron-oxide nanoparticles, into rats prior to extracting bone marrow from them. Then, after enriching the mixture for mesenchymal stem cells, the investigators injected it into the sites of knee injuries in recipient rats. They followed the implanted cells' progress for up to four weeks, comparing the results with those obtained both from cells labeled in laboratory dishes and from unlabeled cells.

Daldrup-Link and others previously have used ferumoxytol for stem-cell labeling in a dish. However, mesenchymal stem cells in a laboratory dish take up very little of this substance. Interestingly, the researchers showed in a series of experiments that, ensconced in donor rats' bone marrow, the same cells are avid ferumoxytol absorbers. Even several weeks after transplantation into the recipient rats' knees, the mesenchymal stem cells retain enough iron to provide a strong MRI signal.

The new labeling technique alleviates the risks of contamination introduced when cells are labeled via manipulations in a laboratory dish — a major regulatory concern, said Daldrup-Link — as well as of a substantial loss of the delicate cells due to their extensive manipulation. It also allows for the immediate transfer of cells from a patient's bone marrow to the site of that patient's own knee injury.

That makes the technique useful in an autologous transplantation procedure, in which cells are extracted from a patient for the purpose of being delivered to another site during the same surgery. Jason Dragoo, MD, associate professor of orthopaedic surgery at the medical school and head team physician for the Stanford football program, plans to initiate a clinical trial this autumn whereby patients in need of knee repair will be treated with mesenchymal stem cells taken from their own bone marrow.

At Dragoo's request, Daldrup-Link's team began seeking a way of avoiding the delay and contamination risk associated with standard ways of labeling mesenchymal stem cells in a culture dish. "He asked us to find a way to label the cells without touching them," Daldrup-Link said. In anticipation of the upcoming clinical trial, one of Dragoo's trainees, medical student Malcolm Debaun, has taken up residence in the Daldrup-Link's lab in order to learn the technique in preparation for the upcoming clinical trial.

Daldrup-Link professes some amusement at the fact that an iron supplement can be used to track stem cells. "Often the simpler approaches are the ones that make it into the clinic," she said.

Stanford has filed a provisional patent on the technique associated with this new use of ferumoxytol. The study was funded by the National Institutes of Health (grants 2R01AR054458-05, CCNE U54 CA119367, CCNE U54 CA151459 and R21CA138353A2).

Other Stanford co-authors are summer student Graham Beck; research assistant Olga Lenkov; research coordinator Jessica Doing; radiology postdoctoral scholars Hossein Nejadnik, MD, PhD, and Grigory Tikhomirov, PhD; statistician Solomon Messing, PhD; Jianghong Rao, PhD, associate professor of radiology; and Paul Kempen, PhD, an assistant professor of materials science and engineering. The study also involved collaborators from UC-San Francisco and BD Biosciences.

Information about Stanford Medicine's Department of Radiology, which also supported the work, is available at http://radiology.stanford.edu.

The Stanford University School of Medicine consistently ranks among the nation's top medical schools, integrating research, medical education, patient care and community service. For more news about the school, please visit http://mednews.stanford.edu. The medical school is part of Stanford Medicine, which includes Stanford Hospital & Clinics and Lucile Packard Children's Hospital. For information about all three, please visit http://stanfordmedicine.org/about/news.html.

Print media contact: Bruce Goldman at (650) 725-2106 (goldmanb@stanford.edu)

Broadcast media contact: M.A. Malone at (650) 723-6912 (mamalone@stanford.edu)

Bruce Goldman | EurekAlert!
Further information:
http://www.stanford.edu

More articles from Life Sciences:

nachricht Water forms 'spine of hydration' around DNA, group finds
26.05.2017 | Cornell University

nachricht How herpesviruses win the footrace against the immune system
26.05.2017 | Helmholtz-Zentrum für Infektionsforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

How herpesviruses win the footrace against the immune system

26.05.2017 | Life Sciences

Water forms 'spine of hydration' around DNA, group finds

26.05.2017 | Life Sciences

First Juno science results supported by University of Leicester's Jupiter 'forecast'

26.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>