Many patients with heart problems - such as heart disease or angina - may need to undergo cardiac surgery in order to restore or improve blood flow. But a new study suggests that the procedure may offer so much more; stem cells in fat discarded during cardiac surgery could be injected back into the patient's heart to further improve its function.
The research team, including senior study author Dr. Ganghong Tian, are due to present their findings at the Frontiers in Cardiovascular Biology meeting in Barcelona, Spain.
Previous research from the team revealed that subcutaneous fat, or adipose tissue, contains stem cells that can improve cardiac function, reduce severity of heart attacks and boost blood vessel regeneration. Such fat can be obtained through liposuction. "But obtaining these from a patient undergoing cardiac surgery requires pre-surgery to collect adipose tissue from the subcutaneous region," says Dr. Tian.
Could there be another option? Dr. Tian explains that during cardiac surgery, fat tissue that resides around the heart - known as mediastinal fat - may often need to be removed from patients in order to fully expose the organ. Could this fat contain stem cells that could be delivered back to the heart to improve its function?
'First evidence that stem cells from mediastinal fat are cardioprotective'
Firstly, the researchers collected mediastinal fat tissue from 24 patients as they underwent cardiac surgery.
Rats that were injected with mediastinal fat stem cells demonstrated greater ventricular movement in their hearts and no reduction in left ventricular ejection fraction.
They found that they were able to isolate a large number of stem cells from the tissue, and that these cells could differentiate into adipocytes (fat cells) and osteocytes (cells found in fully formed bones), which expressed markers for cardiomyocytes (cells found in heart muscles).
The researchers then tested whether stem cells from mediastinal fat tissue could improve the heart function of 13 rats with congestive heart failure. The researchers injected the stem cells directly into the rats' hearts. As a control, an additional five rats with congestive heart failure were injected with a saline solution.
After 6 weeks, the rats underwent magnetic resonance imaging (MRI). The team found that compared with the rats that received the saline solution, those that received mediastinal fat stem cells demonstrated greater ventricular movement in their hearts and no reduction in left ventricular ejection fraction - a measurement of how much blood is being pumped out of the left ventricle of the heart.
Commenting on the team's findings, Dr. Tian says:
"This is the first evidence that stem cells collected from the mediastinal fat region are cardioprotective.
They displayed the same cardioprotective capacity we found in our previous research on stem cells from subcutaneous fat tissue. This raises the exciting possibility of using a patient's own stem cells, isolated from waste tissue during cardiac surgery, to improve their heart function."
He notes that there are currently some issues with this procedure that need to be addressed with further research. For example, a technique needs to be developed that can isolate stem cells from mediastinal fat quickly so they can be injected back into a patient's heart during cardiac surgery.
"It currently takes several hours to purify the cells and we are looking for collaborators to help us devise a more efficient method," explains Dr. Tian.
They also plan to see whether the stem cells can improve cardiac function long-term, beyond the 6 weeks monitored in this study. Furthermore, they aim to induce the stem cells into functional cardiomyocytes that display electrical pulses and beating.
As recently reported by Medical News Today, scientists from Abertay University in the UK have grown miniature beating human hearts in a laboratory in which they can induce heart disease, enabling them to test newly developed drugs against the condition.