Cardiosphere stem cell clusters derived outside of the body from stem cells native to heart tissue, a new form of stem cell, were used by the researchers. Structures of cardiospheres comprise of non-specialised stem cells in the core with an outer layer of specialised heart cells, which mimics native environment of heart muscle stem cells, and has been shown to improve stem cell survival rates, making the stem cells able to make up cell losses following heart attack. Delivering the clusters to patients using conventional routes is proving to be difficult due to the risk of them entering blood circulation blocking blood vessels causing embolism.
Delivery of medicine into the pericardium has received very little attention as a route for delivering stem cells to the heart, but is commonly used to deliver drugs to treat heart disease. Cardiospheres were delivered to the heart by using the intrapericardial administration method, as it was thought the pericardial cavity would retain them, preventing micro-embolization and limit loss of stem cells into circulation or other tissues. Cardiospheres were optimised by treatment with fluid from the pericardial cavity before delivery into model rats.
Heart tissue analyses was conducted after four weeks, results showed increased survival and retention rates of the implanted stem cells, and higher migration of stem cells from the pericardium to heart muscles including areas affected by the heart attack was observed. Improved heart function and survival rate was also observed compared to previous methods. Intrapericardial implantation has been shown as a promising delivery route for stem cell therapy, and stem cell viability and function can be enhanced outside the body before implantation; both resulting in improved regeneration of heart muscle following heart attack.
It was noted that although the results are promising and exciting the study has limits due to the fact data was obtained via model animals; and this was the first investigation of cardiospheres via pericardial routing. Further studies are required to clarify additional questions pertaining to humans, stem cell migration, and which molecules best enhance stem cell potency to promote cell regeneration in the heart muscle.
