Cardiocyte nuclear chromatin density correlates with transplanted heart left ventricular mass

Area of Science:

• Cardiology
• Cell Biology
• Transplantation Medicine

Background:

• Cardiomyocyte hypertrophy is linked to polyploidy, characterized by reduced nuclear chromatin density.
• Repeated heart biopsies allow dynamic assessment of these changes in transplanted hearts.

Purpose of the Study:

• To evaluate cardiomyocyte nuclear chromatin density in transplanted hearts during long-term follow-up.
• To correlate chromatin density changes with cardiac remodeling and polyploidy.

Main Methods:

• Analysis of myocardial biopsy specimens from 122 heart transplant recipients (no rejection) up to 10 years post-surgery.
• Evaluation of cardiomyocyte nuclear chromatin mean gray level and its correlation with nuclear area and left ventricle dimensions via ultrasound.
• Comparison with 7 donor heart specimens as controls.

Main Results:

• Mean gray level of cardiomyocyte nuclear chromatin decreased over time, correlating positively with interventricular septum thickness, left ventricle posterior wall diameter, and left ventricular mass.
• Positive correlation between mean gray level and nuclear surface area at years 3, 4, and 9 suggested polyploidy.
• Negative correlation at 1 week and 1 year indicated early cardiomyocyte hypertrophy normalization.

Conclusions:

• Chromatin condensation (pyknosis) occurs over time in transplanted hearts.
• Cardiomyocyte chromatin activity correlates with left ventricular hypertrophy.
• Compensatory cardiomyocyte polyploidy appears to be a periodical phenomenon in heart transplants.