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Published on: October 25, 2015
Preterm Birth With Neonatal Interventions Accelerates Collagen Deposition in the Left Ventricle of Lambs Without
Bianca Lê1, Mar Janna Dahl2, Kurt H Albertine2
1Department of Anatomy and Developmental Biology and Biomedicine Discovery Institute, Monash University, Clayton, Victoria, Australia.
Insights
Preterm birth and ventilation in lambs did not affect cardiomyocyte growth but increased collagen in the left ventricle. This collagen buildup may lead to cardiac dysfunction later in life.
Area of Science:
- Cardiovascular Physiology
- Neonatal Research
- Cardiac Remodeling
Background:
- Adults born preterm (<37 weeks' gestation) have altered cardiac growth and are prone to cardiac dysfunction.
- Previous sheep studies indicated moderate preterm birth causes maladaptive cardiac remodeling.
Purpose of the Study:
- To investigate ventricular structure in lambs born at a greater severity of preterm birth and mechanically ventilated postnatally.
- To assess the long-term cardiac effects of severe preterm birth and neonatal respiratory support.
Main Methods:
- Compared former-preterm lambs (128 days gestation, ventilated) with term-born lambs (150 days gestation, unventilated) at 2 and 5 months term-equivalent age.
- Utilized immunohistochemistry, histology, and stereology to analyze right and left ventricular structure.
Main Results:
- Cardiomyocyte number, size, proliferation, and apoptosis were unaffected by preterm birth or age.
- Interstitial collagen increased with age in the left ventricle plus septum, and this was exacerbated by preterm birth.
- Right ventricle collagen increased with age but was not influenced by preterm birth.
Conclusions:
- This study is the first to examine the impact of preterm birth and neonatal interventions on lamb ventricular myocardium.
- No adverse effects on cardiomyocyte growth were observed in early postnatal life.
- Increased collagen deposition in preterm hearts is a concern, potentially leading to cardiac dysfunction with aging.
Background:
Adults born preterm (< 37 weeks' gestation) exhibit altered cardiac growth and are susceptible to cardiac dysfunction. Sheep studies have shown that moderate preterm birth results in maladaptive structural remodelling of the cardiac ventricles. The aim of this study was to examine ventricular structure in lambs born at a greater severity of preterm birth and ventilated postnatally.
Methods:
Former-preterm lambs delivered at 128 days' gestation, and mechanically ventilated for a week after birth, were compared with unventilated lambs born at term (150 days' gestation), at 2 months (term: n = 10, former-preterm: n = 8), and 5 months (term: n = 9, former-preterm: n = 8) term-equivalent age. The right ventricle and left ventricle plus septum were analysed using immunohistochemistry, histology, and stereology.
Results:
Cardiomyocyte number, cross-sectional area, proliferation, and apoptosis were not affected by preterm birth or age. Left ventricle plus septum interstitial collagen levels increased with age (P = 0.0015) and were exacerbated by preterm birth (P = 0.0006; 2 months term: 0.57% ± 0.07%, former-preterm: 1.44% ± 0.18%; 5 months term: 1.37% ± 0.25%, former-preterm: 2.15% ± 0.31%). Right ventricle interstitial collagen levels increased with age (P = 0.012) but were not affected by preterm birth.
Conclusion:
This study is the first to explore the effect of preterm birth combined with modern neonatal interventions on the ventricular myocardium in lambs. There was no adverse impact on cardiomyocyte growth in early postnatal life. Of concern, however, there was increased collagen deposition in the preterm hearts, which has the potential to induce cardiac dysfunction, especially if it becomes exaggerated with ageing.
