Background
The human myocardium harbours a population of resident endogenous cardiac stem cells (eCSCs). They express the stem cell factor receptor, c-kit, are distributed throughout the myocardium, are clonogenic, self-renewing and multi-potent.The objective of this study is to determine whether c-kitpos eCSCs isolated from the different cardiac chambers have a distinct transcriptional profile depending on the chamber of origin.

Material and Methods
c-kitpos eCSCs were isolated by enzymatic digestion and purified by Magnetic Activated Cell Sorting. mRNA was isolated using Qiagen® microRNA kit, and then reverse transcribed using first strand cDNA synthesis with random hexamers. qRT-PCR was performed using SYBR Green on a MyIQ thermocycler for specific genes representative of the primary and secondary heart field, and their chamber of origin developmental program.

Results
From the 15 samples the c-kitpos eCSCs isolated are distributed throughout the myocardium. Transcriptional analysis revealed that all the 4 cardiac chambers host c-kitpos eCSCs. These express most of the genes from the first and secondary heart field. Expression of transcripts for c-kit, Foxh1, Hand1, Hand2, Pitx-2, Tbx-5, Tbx-20, Hrt1, Hrt2, Fgf-8, Fgf-10, and Isl-1 were found at differential levels.

Conclusion
This study is the first to show in humans that c-kitpos eCSCs don’t appear to have a ‘chamber- specific’ transcript footprint, and are therefore interchangeable between cardiac chambers. The eCSCs isolated from all the 4 cardiac chambers seems that they have a universal genetical profile despite their chamber of origin.