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Updated: Jul 17, 2026
In Vitro Differentiation of Human Mesenchymal Stem Cells into Functional Cardiomyocyte-like Cells
Published on: August 9, 2017
Chimerism and microchimerism of the human heart: evidence for cardiac regeneration
Antoni Bayes-Genis1, Santiago Roura, Cristina Prat-Vidal
1Cardiac Regeneration Program, Cardiology Service, Hospital de la Santa Creu i Sant Pau, Institut Català de Ciencies Cardiovasculars, Departament de Medicina, Universitat Autònoma de Barcelona, Barcelona 08025, Spain. abayesgenis@santpau.es
Insights
Human heart regeneration is possible, as shown by studies of heart transplant recipients. Chimerism, the presence of donor cells, indicates the heart has a natural regenerative capacity, though insufficient for repairing damaged hearts.
Area of Science:
- Cardiology
- Regenerative Medicine
- Cell Biology
Background:
- The human heart was long considered incapable of regeneration.
- Recent studies explore the heart's potential for self-repair.
Purpose of the Study:
- To investigate the regenerative potential of the human heart using chimerism studies.
- To determine if extracardiac cells contribute to myocardial tissue.
Main Methods:
- Analysis of sex-mismatched heart transplant recipients.
- Tracing Y chromosome using fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR).
- Quantifying cardiac chimerism levels.
Main Results:
- Cardiac chimerism detected in heart transplant recipients, ranging from 0.04% to 10.0%.
- Low-level chimerism (approx. 0.20%) observed after bone marrow transplantation, suggesting myeloid origin.
- Fetal cell microchimerism demonstrated, with fetal cells capable of myocardial differentiation.
Conclusions:
- Chimerism studies provide proof-of-concept for natural cardiac homeostasis in humans.
- The observed chimerism is insufficient for significant repair in diseased hearts.
- The human heart possesses a degree of regenerative potential through cell migration and differentiation.
Abstract:
For decades, it has been widely accepted that the heart is a terminally differentiated organ that is unable to regenerate. Studies of recipients of hearts donated by other humans have shed light on the regenerative potential of the human heart. Investigators have been able to trace the Y chromosome by fluorescence in situ hybridization or polymerase chain reaction, or both, in sex-mismatched heart recipients. Cardiac chimerism has been reported, with concentrations of chimeric cells ranging from 0.04% to 10.0%. Cardiac chimerism after bone marrow or progenitor cell transplantation has also been reported to a low extent (approximately 0.20%), suggesting that a fraction of the extracardiac cells that colonize the myocardium are of bone marrow origin. Cardiac chimerism after pregnancy with male offspring (fetal cell microchimerism) has also been demonstrated. Cells of fetal origin have been shown to be capable of differentiating into myocardial cells. Collectively, we show that chimerism studies provide a proof of concept of a process that it is likely to be part of normal cardiac homeostasis in humans but apparently insufficient for cardiac repair in diseased hearts.
