Human fat cells tweaked to work like heart's pacemaker: Study

In a first, researchers, including one of Indian-origin, have reprogrammed the human body's fat cells into those similar to the heart's pacemaker cells which control heartbeat by creating rhythmic electrical impulses , an advance that may lead to new therapies for cardiac failure.

The study, published in the Journal of Molecular and Cellular Cardiology, noted that the new pacemaker-like cell may become a useful alternative treatment for heart conduction system disorders, and to bridge the limitations of current treatments such as artificial electronic pacemaker implants.

According to an earlier study, published in the Journal of Geriatric Cardiology, each year more than one million artificial pacemakers are implanted in patients globally.

The device is placed in the chest or abdomen, and uses electrical pulses to prompt the heart to beat normally.

However, the device needs to be periodically examined by a physician, and over time it can stop working properly.

In the current study, researchers, including Suchi Raghunathan from the University of Houston in the US, tweaked unspecialised stem cells to turn them into conducting cells of the heart that could carry electrical current.

The researchers, in an earlier study, had turned the stem cells residing in the human body's fat cells into cardiac progenitor cells.

With the current study, they showed that these cardiac progenitor cells can be programmed to conduct current and keep hearts beating.

They said, its functioning is similar to the heart's natural node of cells called the sinoatrial node (SAN) -- part of the electrical cardiac conduction system (CCS).

The scientists noted that the SAN is the primary pacemaker of the heart, responsible for generating the electric impulse or its 'beat'.

According to the study, the heart's native cardiac pacemaker cells are confined within the SAN -- a small structure comprised of just a few thousand specialized pacemaker cells.

It noted that a failure of the SAN, or a block at any point in the CCS resulted in irregular heartbeats, also called arrhythmias.

"Batteries will die. Just look at your smartphone. This biologic pacemaker is better able to adapt to the body and would not have to be maintained by a physician. It is not a foreign object," said study co-author Bradley McConnell from the University of Houston.

He said the cells would be able to grow with the body, and become much more responsive to what the body is doing.

As part of the study, the scientists infused lab-grown fat cells from the heart with a unique cocktail of three molecules called transcription factors that could induce gene activity.

They also supplied these cells with molecules called plasma membrane channel proteins, which are gates opening up in cells to allow outside chemicals.

Using these molecules, the team could reprogram the heart cells in vitro.

"In our study, we observed that the SHOX2, HCN2, and TBX5 (SHT5) cocktail of transcription factors and channel protein reprogrammed the cells into pacemaker-like cells," McConnell said.

The researchers said the combination of these biomolecules may facilitate the development of cell-based therapies for various cardiac conduction diseases.