Mesenchymal stem cells have become attractive tools for bioengineers, but some scientists haven’t given up on their regenerative potential
Stem cell scientists had what first appeared to be an easy win for regenerative medicine when they discovered mesenchymal stem cells several decades ago. These cells, found in the bone marrow, can give rise to bone, fat, and muscle tissue, and have been used in hundreds of clinical trials for tissue repair. Unfortunately, the results of these trials have been underwhelming. One problem is that these stem cells don’t stick around in the body long enough to benefit the patient.
But Harvard Stem Cell Institute (HSCI) scientists at Boston Children’s Hospital aren’t ready to give up. A research team led by Juan Melero-Martin, PhD, recently found that transplanting mesenchymal stem cells along with blood vessel-forming cells naturally found in circulation improves results. This co-transplantation keeps the mesenchymal stem cells alive longer in mice after engraftment, up to a few weeks compared to hours without co-transplantation. This improved survival gives the mesenchymal stem cells sufficient time to display their full regenerative potential, generating new bone or fat tissue in the recipient mouse body. The finding was published in the Proceedings of the National Academy of Sciences (PNAS).
“We are losing mesenchymal stem cells very rapidly when we transplant them into the body, in part, because we are not giving them what they need,” said Melero-Martin, an HSCI affiliated faculty member and an assistant professor of surgery at Boston Children’s Hospital, Harvard Medical School.
“In the body, these cells sit very close to the capillaries, constantly receiving signals from them, and even though this communication is broken when we isolate mesenchymal stem cells in a laboratory dish, they seem to be ok because we have learned how to feed them,” he said. “But when you put the mesenchymal stem cells back into the body, there is a period of time when they will not have this proximity to capillary cells and they start to die; so including these blood vessel-forming cells from the very beginning of a transplantation made a major difference.”
Melero-Martin's research has immediate translational implications, as current mesenchymal clinical trials don’t follow a co-transplantation procedure. He is already collaborating with surgical colleagues at Boston Children’s Hospital to see if his discovery can help improve fat and bone grafts. However, giving patients two different types of cells, as opposed to just one, would require more time and experiments to determine safety and efficacy. Melero-Martin is seeking to identify the specific signals mesenchymal stem cells receive from the blood vessel-forming cells in order to be able to mimic the signals without the cells themselves.
“Even though mesenchymal stem cells have been around for a while, I think there is still a lack of fundamental knowledge about communication between them and other cells in the body,” he said. “My lab is interested in going even beyond what we found to try to understand whether these cell-cell signals are different in each tissue of the body, and to learn how to educate both blood vessel-forming and mesenchymal stem cells to co-ordinate tissue specific regenerative responses.”
Other Harvard Stem Cell Institute researchers are studying mesenchymal stem cells as bioengineering tools to deliver therapeutics, which is possible because of the cell type’s unique ability to not trigger an immune response. Jeffrey Karp, PhD, at Brigham and Women’s Hospital has developed several methods to turn these cells into drug-delivery vehicles, so that after transplantation they can, for example, hone in on swollen tissue and secrete anti-inflammatory compounds. And Khalid Shah, PhD, at Massachusetts General Hospital has designed a gel that holds mesenchymal stem cells in place so that they can expose brain tumors to cancer-killing herpes viruses.
“A lot of these applications have no real direct link with mesenchymal stem cells’ supposed progenitor cell function,” Melero-Martin said. “In our study, we went back to the collective ambition to use these cells as a way to regenerate tissues and we are not in a position to say how that affects other uses that people are proposing.”
This work was supported by the National Institutes of Health. Ruei-Zeng Lin, PhD, a research fellow in surgery at Boston Children’s Hospital, is first author on the PNAS paper.
Cited: Lin, et. al., "Human endothelial colony-forming cells serve as trophic mediators for mesenchymal stem cell engraftment via paracrine signaling" Proceedings of the National Academy of Sciences (June 30, 2014), doi: 10.1073/pnas.1405388111
Advancing Biomedicine From Classroom to Clinic
The Harvard Stem Cell Institute and Harvard Department of Stem Cell and Regenerative Biology advance the understanding of human development and disease, support the discovery of stem cell-based therapies and cures for diseases, create collaborations across traditional institutional and disciplinary boundaries, and teach and train the next generation of leading stem cell scientists.
Joseph Caputo | Eurek Alert!
Toward a 'smart' patch that automatically delivers insulin when needed
18.01.2017 | American Chemical Society
127 at one blow...
18.01.2017 | Stiftung Zoologisches Forschungsmuseum Alexander Koenig, Leibniz-Institut für Biodiversität der Tiere
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
18.01.2017 | Power and Electrical Engineering
18.01.2017 | Materials Sciences
18.01.2017 | Life Sciences