The new study has found that stem cell therapy promotes recovery from a heart attack in an unpredictable way. While the study results are quite conflicting with the biological reasons that were anticipated nearly twenty years ago.
These latest findings were presented in the journal “Nature” on November 27. And indicates that heart stem cells cannot repair dead or damaged heart cells by simply replacing them. Instead, they provide a wound healing-like effect in a completely different way.
The study shows that if injured hearts of mice are inoculated with dead or living heart stem cells, they initiate a severe inflammatory response. And later, in the injured part of the heart, this response will increase mechanical properties via the generation of a wound healing-like effect.
According to the study’s leading investigator, Jeffery Molkentin, the secondary healing process facilitated by the immune system cells (macrophages), improves the function of the heart after a heart attack.
The activity of the cells present around the heart’s injured area is altered by innate immunity to promote heart recovery and the better contraction of heart muscles.
Currently, almost all the clinical trials related to stem cell therapy are based on the study proposed by the journal “Nature” about two decades ago. Previously, it was thought that the inoculation of C-kit positive heart stem cells into a broken heart may lead to cardiomyocytes regeneration.
However, the results of the latest research by Molkentin and colleagues show that current cell therapy-based clinical trials should be reassessed to find how this therapy may act to show its beneficial effects.
In this study, the research team was working on cardiac progenitor cells and bone marrow mononuclear cells (types of heart stem cells). And while trying to test and re-assess the data under various conditions, the team made a discovery.
Zymosan is an inert chemical also known to initiate an innate immune response. The researchers found that inoculating dead cells or even zymosan can also improve heart function by enhancing the process of healing.
Researchers found that therapies including zymosan or stem cells can bring change to immune responses. That will cause a reduction in connective tissue formation in the extracellular matrix of injured areas. Additionally, it will also enhance the scar’s mechanical properties.
Previously, in most of the human clinical trials, stem cells were injected directly into the blood (via the use of IV) due to safety concerns. But now, the latest discoveries have allowed the inoculation of therapeutic substances (such as zymosan) directly into the area affected by infarction.
And shows that these therapeutic substances require direct entry to the heart tissue. The research team has also observed another unpredictable outcome related to zymosan. This chemical has the ability to attach with a pattern recognition center and initiate an acute innate immune response.
The application of zymosan for heart recovery in mice has led to enhanced and long-lasting effects on injured tissue than injecting dead cell debris or stem cells. And Molkentin said that further testing to improve the process of wound-healing may act as a breakthrough to develop future treatment strategies.