Dual roles for bone marrow-derived Sca-1 cells in cardiac function.

Area of Science:

• Cardiovascular Biology
• Stem Cell Biology
• Immunology

Background:

• Bone marrow (BM) stem cell recruitment is crucial for cardiac healing but declines with age.
• Aging impairs the efficiency of endogenous stem cell mobilization for heart repair.

Purpose of the Study:

• To investigate the role of young stem cell antigen 1 (Sca-1)-positive BM cells in the aged heart.
• To determine the impact of Sca-1+ BM cells on cardiac function and healing post-myocardial infarction (MI).

Main Methods:

• Bone marrow reconstitution in aged mice using Sca-1+ and Sca-1- BM cells from young GFP+ mice.
• Induction of myocardial infarction (MI) and subsequent analysis via microarray and cell staining (Mac-3, F4/80).

Main Results:

• Sca-1+ BM cell reconstitution led to preserved cardiac function after MI.
• Upregulation of serum response factor, VEGF-A, and myogenic genes, with downregulation of IL-1β at baseline.
• Enhanced inflammatory response post-MI in Sca-1+ recipients, with increased cytokine expression and inflammatory cell markers.
• Postinfarction hearts contained a mix of donor (GFP+) and host (GFP-) macrophages.

Conclusions:

• Sca-1+ BM cells promote cardiac healing through an acute inflammatory response post-MI.
• These cells also establish a beneficial cardiac niche before injury, improving cardiac function.
• Young Sca-1+ BM cells offer a potential therapeutic strategy for age-related cardiac dysfunction.