ABSTRACT
BACKGROUND: Although efforts continue to find new therapies to regenerate infarcted heart tissue, knowledge of the cellular and molecular mechanisms involved remains poor. OBJECTIVES: This study sought to identify the origin of cardiac fibroblasts (CFs) in the infarcted heart to better understand the pathophysiology of ventricular remodeling following myocardial infarction (MI). METHODS: Permanent genetic tracing of epicardium-derived cell (EPDC) and bone marrow-derived blood cell (BMC) lineages was established using Cre/LoxP technology. In vivo gene and protein expression studies, as well as in vitro cell culture assays, were developed to characterize EPDC and BMC interaction and properties. RESULTS: EPDCs, which colonize the cardiac interstitium during embryogenesis, massively differentiate into CFs after MI. This response is disease-specific, because angiotensin II-induced pressure overload does not trigger significant EPDC fibroblastic differentiation. The expansion of epicardial-derived CFs follows BMC infiltration into the infarct site; the number of EPDCs equals that of BMCs 1 week post-infarction. BMC-EPDC interaction leads to cell polarization, packing, massive collagen deposition, and scar formation. Moreover, epicardium-derived CFs display stromal properties with respect to BMCs, contributing to the sustained recruitment of circulating cells to the damaged zone and the cardiac persistence of hematopoietic progenitors/stem cells after MI. CONCLUSIONS: EPDCs, but not BMCs, are the main origin of CFs in the ischemic heart. Adult resident EPDC contribution to the CF compartment is time- and disease-dependent. Our findings are relevant to the understanding of post-MI ventricular remodeling and may contribute to the development of new therapies to treat this disease.
Subject(s)
Bone Marrow Cells/pathology , Cicatrix/pathology , Fibroblasts/pathology , Myocardial Infarction/pathology , Myocytes, Cardiac/pathology , Ventricular Remodeling , Animals , Cell Differentiation , Cells, Cultured , Cicatrix/etiology , Cicatrix/physiopathology , Disease Models, Animal , Mice , Mice, Inbred C57BL , Myocardial Infarction/complications , Myocardial Infarction/physiopathology , Pericardium/pathologyABSTRACT
The amyloid-beta peptide cascade hypothesis has provided a useful framework for the research on Alzheimer's disease for nearly 20 years. According to this hypothesis, an increase in amyloid-beta levels triggers all of the pathological features of the disease, including tau hyperphosphorylation, appearance of neurofibrillary tangles, synaptic dysfunction and neuronal cell death. Even though amyloid-beta peptide has an important role in the neurodegenerative process, different findings, such as the presence of abundant plaques in old cognitively normal individuals or the limited success of therapeutical approaches targeting only amyloid-beta, cast some doubt on a unique role for this peptide. At present, it is rather accepted that amyloid-beta peptide acts in parallel with other factors causing Alzheimer's disease that should be also considered at the time of designing useful therapeutic strategies.
Subject(s)
Alzheimer Disease/etiology , Alzheimer Disease/pathology , Amyloid beta-Peptides/metabolism , Alzheimer Disease/physiopathology , Alzheimer Disease/therapy , Animals , Animals, Genetically Modified , Apolipoprotein E4/genetics , Cell Death , Humans , Nerve Degeneration/metabolism , Nerve Degeneration/pathology , Neurofibrillary Tangles/metabolism , Neurofibrillary Tangles/pathology , Neurons/metabolism , Neurons/pathology , Risk Factors , tau Proteins/metabolismABSTRACT
Resumen. La hipótesis de la cascada del péptido beta-amiloide ha proporcionado un marco de referencia útil para las investigaciones sobre la enfermedad de Alzheimer desde hace cerca de 20 años. De acuerdo con esta hipótesis, el aumento de beta-amiloide es lo que da lugar a todas las características patológicas de la enfermedad, incluyendo la hiperfosforilación de tau, la formación de ovillos neurofibrilares, la disfunción sináptica y la muerte neuronal. Aunque está claro que el beta-amiloide desempeña un papel importante en el proceso neurodegenerativo, diversos hallazgos, como la abundante presencia de placas en individuos ancianos cognitivamente normales o el escaso éxito de aproximaciones terapéuticas dirigidas únicamente contra este péptido, hacen dudar de que sea el único responsable. En la actualidad, se estima más bien que el péptido beta-amiloide actúa en paralelo con otros factores responsables del proceso patógeno, que deben tenerse en cuenta a la hora de diseñar estrategias útiles para el tratamiento de la enfermedad (AU)
Summary. The amyloid-beta peptide cascade hypothesis has provided a useful framework for the research on Alzheimers disease for nearly 20 years. According to this hypothesis, an increase in amyloid-beta levels triggers all of the pathological features of the disease, including tau hyperphosphorylation, appearance of neurofibrillary tangles, synaptic dysfunction and neuronal cell death. Even though amyloid-beta peptide has an important role in the neurodegenerative process, different findings, such as the presence of abundant plaques in old cognitively normal individuals or the limited success of therapeutical approaches targeting only amyloid-beta, cast some doubt on a unique role for this peptide. At present, it is rather accepted that amyloid-beta peptide acts in parallel with other factors causing Alzheimers disease that should bealso considered at the time of designing useful therapeutic strategies (AU)
