If a patient has a heart failure, there is little you can do for them. Medications can take some of the stress off the failing heart, and in extreme cases, a heart transplant is warranted. However, organ transplants are hampered by both the limited number of organ donors and the potential for the patient’s body to reject the new heart.
A new study from the journal STEM CELLS Translational Medicine has shown that heart tissue can be regenerated if engineered patches made up of a mixture of fibrin and mesenchymal stem cells (MSCs) derived from human umbilical cord blood are applied to the heart.
Previous studies show the potential of MSCs to repair damage generated by a heart attack. In these clinical studies, the MSCs were delivered through injections into the heart muscle or intravenously. “While feasible and safe, the treatments exhibited only modest benefits,” said Antoni Bayes-Genis, M.D., Ph.D., member of the ICREC (Heart Failure and Cardiac Regeneration) Research Program, Germans Trias i Pujol Health Science Research Institute (IGTP) and professor at Universitat Auto`noma de Barcelona. Dr. Bayes-Genis is a lead investigator on this study.
“The survival rate of the implanted stem cells was generally low and about 90 percent of them either died or migrated away from the implantation site, generally to the liver,” added the study’s first author, Santiago Roura, Ph.D., also a member of the ICREC Research Program and IGTP. “These limited effects are probably due to the adverse mechanical stress and hypoxic conditions present in the myocardium after the heart attack.”
Now could a better way to deliver the MSCs to the injured site yield more efficient results? Synthetic scaffolds (or patches) in which the cells are embedded in matrices constructed of biological and/or synthetic materials and supplemented with growth or differentiation factors can generate so-called “bioimplants.” Bioimplants are a promising way to potentially apply stem cells to the heart in a way that will allow them to survive, grow and thrive. Unfortunately, none of the current materials being tested for heart patches, whether synthetic or natural has been shown to provide optimal properties for cardiac tissue repair.
Dr. Bayes-Genis and his colleagues examined how a fibrin patch filled with human umbilical cord blood-derived MSCs might serve to repair a damaged heart. Fibrin is widely used in medical applications, since it can act as a bio-compatible glue that holds cells in place and stimulating the production of new blood vessels (angiogenesis). Bayes-Genis and others hypothesized that fibrin scaffolds might offer a nurturing environment for the growth and proliferation of MSCs at the site of the heart injury. There, the cells could induce the repair of damaged heart tissue.
Bayes-Genis and coworkers mixed MSCs and fibrin to form the patches that were then applied to the hearts of mice that had undergone heart attacks. Three weeks later, they compared the recovery of these animals to a control group of mice that were treated with fibrin alone without embedded stem cells, and a third group that received no treatment at all. The results showed that the patches adhered well to the hearts and the MSCs grew and differentiated. The patch cells also participated in the formation of new, functional blood vessels that connected the patch to both the heart tissue directly beneath it and the mouse’s endogenous circulatory system, too.
“As a result, the heart function in this group of mice was better than that of the animals in either of the other control groups,” Dr. Bayes-Genis said. “Thus, this study provides promising findings for the use of umbilical cord-blood MSCs and fibrin patches in cardiac repair.”
“This is an interesting study that suggests a news strategy for using stem cells to repair injured heart tissue, without the drawbacks that cell injections have shown,” said Anthony Atala, M.D., Editor-in-Chief of STEM CELLS Translational Medicine and Director of the Wake Forest Institute for Regenerative Medicine.