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Immunohistochemical expression of cell differentiation and growth in neonate cardiomyocytes
Tarcísio Fulgêncio Alves da Silva1, Greyce Kelly de Souza, Mona Adalgisa Simões
1Pontifícia Universidade Católica do Paraná - PUC-PR1, Brazil.
Insights
Human neonatal cardiomyocytes initially proliferate, indicated by Ki67 expression, then differentiate, showing increased HHF35 and sarcomeric actin, during the transition to extrauterine life.
Area of Science:
- Cardiovascular research
- Neonatal physiology
- Cellular biology
Background:
- Human neonatal cardiac transition to extrauterine life involves poorly understood cell mechanisms.
- Animal studies have explored cardiac alterations, but human data is limited.
Purpose of the Study:
- To investigate cardiomyocyte differentiation mechanisms in early human life.
- To analyze proteins involved in proliferation and muscle contraction in neonate myocardium.
Main Methods:
- Cross-sectional study of neonatal myocardium autopsy samples (NEO1: 0-2 days, NEO2: 3-10 days).
- Immunohistochemical analysis using antibodies for proliferation (Ki67, PCNA, PTEN, Bcl2) and contractile proteins (HHF35, sarcomeric actin).
Main Results:
- Ki67 expression was higher in the NEO1 group (0-2 days).
- HHF35 and sarcomeric actin expression were significantly higher in the NEO2 group (3-10 days).
Conclusions:
- Neonatal cardiomyocytes exhibit proliferation in the first two days of life.
- A shift towards differentiation, marked by increased contractile protein expression, occurs between 3-10 days post-birth.
Background:
The cardiac alterations during the fetal heart transition to extrauterine life have been explored by several animal studies and the cell mechanisms responsible for these modifications are not well documented in humans.
Objective:
To evaluate the mechanism of cell differentiation into cardiomyocytes that occur in the first days of life, through immunohistochemical analysis of proteins involved in proliferation and muscle contraction processes, in samples of human neonate myocardium.
Methods:
Cross-sectional study of paraffin-sample sections of myocardium from an autopsy database of human neonates, divided into two sample groups: full-term neonates who died after a maximum of two days of life (NEO1) with 10 cases, and full-term infants who died between 3 and 10 days of life (NEO2) with 14 cases, in order to follow a temporal line that would contemplate the transition from fetal circulation to extrauterine life. The samples were studied in tissue microarray and the antibodies used were Ki67, PCNA, PTEN, Bcl2 (proliferation), HHF35 and sarcomeric actin (contractile proteins).
Results:
Difference was observed regarding Ki67, p = 0.02; HHF35, p <0.01 and sarcomeric actin, p = 0.02, with Ki67 expression being higher in NEO1 group, whereas HHF35 and sarcomeric actin expression was higher in the NEO2 group.
Conclusion:
The results suggest that cardiomyocytes have a proliferation characteristic (Ki67) in NEO1 which, following a temporal line, will be replaced by a differentiation characteristic (HHF35 and sarcomeric actin) in NEO2.
