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Mesenchymal-endothelial transition contributes to cardiac neovascularization.

Ubil E, Duan J, Pillai IC, Rosa-Garrido M, Wu Y, Bargiacchi F, Lu Y, Stanbouly S, Huang J, Rojas M, Vondriska TM, Stefani E, Deb A - Nature (2014)

Bottom Line: We show that the transcription factor p53 regulates such a switch in cardiac fibroblast fate.Loss of p53 in cardiac fibroblasts severely decreases the formation of fibroblast-derived endothelial cells, reduces post-infarct vascular density and worsens cardiac function.These observations demonstrate that mesenchymal-to-endothelial transition contributes to neovascularization of the injured heart and represents a potential therapeutic target for enhancing cardiac repair.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology &Physiology, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599, USA.

ABSTRACT
Endothelial cells contribute to a subset of cardiac fibroblasts by undergoing endothelial-to-mesenchymal transition, but whether cardiac fibroblasts can adopt an endothelial cell fate and directly contribute to neovascularization after cardiac injury is not known. Here, using genetic fate map techniques, we demonstrate that cardiac fibroblasts rapidly adopt an endothelial-cell-like phenotype after acute ischaemic cardiac injury. Fibroblast-derived endothelial cells exhibit anatomical and functional characteristics of native endothelial cells. We show that the transcription factor p53 regulates such a switch in cardiac fibroblast fate. Loss of p53 in cardiac fibroblasts severely decreases the formation of fibroblast-derived endothelial cells, reduces post-infarct vascular density and worsens cardiac function. Conversely, stimulation of the p53 pathway in cardiac fibroblasts augments mesenchymal-to-endothelial transition, enhances vascularity and improves cardiac function. These observations demonstrate that mesenchymal-to-endothelial transition contributes to neovascularization of the injured heart and represents a potential therapeutic target for enhancing cardiac repair.

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MEndoT after cardiac injury is p53 dependent(a–c) p53 immunostaining in Col1a2CreERT:R26RtdTomato and Col1a2CreERT:R26RtdTomato:p53CKO hearts (arrowheads) and (c) quantification of p53 expression in labeled fibroblasts (* p<0.005). (d–f) VECAD immunostaining in labeled fibroblasts (arrowheads) and (f) Labeled fibroblasts(%) expressing VECAD (* p<0.005). (g) Number of endothelial cells/high power field (* p<0.005, n=5 animals) (h,i) Cardiac function prior to and 7 days after injury. (*p<0.05, n=9 animals). (j) Masson’s Trichrome staining 14 days after injury. (k) Quantitation of fibrosis (* p<0.05). (n=4 animals unless mentioned, All graphs show mean±S.E.M., scale bar: 10μm).
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Figure 3: MEndoT after cardiac injury is p53 dependent(a–c) p53 immunostaining in Col1a2CreERT:R26RtdTomato and Col1a2CreERT:R26RtdTomato:p53CKO hearts (arrowheads) and (c) quantification of p53 expression in labeled fibroblasts (* p<0.005). (d–f) VECAD immunostaining in labeled fibroblasts (arrowheads) and (f) Labeled fibroblasts(%) expressing VECAD (* p<0.005). (g) Number of endothelial cells/high power field (* p<0.005, n=5 animals) (h,i) Cardiac function prior to and 7 days after injury. (*p<0.05, n=9 animals). (j) Masson’s Trichrome staining 14 days after injury. (k) Quantitation of fibrosis (* p<0.05). (n=4 animals unless mentioned, All graphs show mean±S.E.M., scale bar: 10μm).

Mentions: To determine whether p53 mediates MEndoT in vivo, we subjected Col1a2CreERT:R26RtdTomato:p53fl/fl mice to ischemic cardiac injury 5 days following cessation of tamoxifen. Mice with intact p53 exhibited 6±0.64 fold increase (mean±S.E.M.) in cardiac fibroblast p53 levels 3 days after cardiac injury, but in mice with fibroblast specific p53 deletion [referred to as Col1a2CreERT:R26RtdTomato:p53CKO (conditional knock out)], the mean p53 expression in border zone cardiac fibroblasts failed to increase significantly (Fig. 3a–c). The degree of MEndoT at 3 days post-injury in Col1a2CreERT:R26RtdTomato:p53CKO animals decreased by 57% (Fig. 3d–f) and was associated with a decrease in capillary density in the injury region (Fig. 3g). Increase in vessel density in the injured heart is a critical post-ischemic repair mechanism. Diminished neovascularization can lead to rapid decline in cardiac function after cardiac injury and is associated with worsened scarring34. Echocardiography on hearts of mice 7 days after cardiac injury showed significant worsening of cardiac function in p53CKO mice (Fig. 3h,i). Masson Trichrome staining demonstrated a greater amount of collagen deposition in the hearts of Col1a2CreERT:R26RtdTomato:p53CKO animals (Fig. 3j,k). The degree of inflammatory infiltrate measured by the number of CD68 expressing macrophages was also significantly higher in the Col1a2CreERT:R26RtdTomato:p53CKO animals (Extended Data Fig. 9a,b,d). These observations demonstrate that p53 is necessary for MEndoT to occur after ischemic cardiac injury and that disruption of MEndoT is associated with diminished post-injury vascularity and cardiac function.


Mesenchymal-endothelial transition contributes to cardiac neovascularization.

Ubil E, Duan J, Pillai IC, Rosa-Garrido M, Wu Y, Bargiacchi F, Lu Y, Stanbouly S, Huang J, Rojas M, Vondriska TM, Stefani E, Deb A - Nature (2014)

MEndoT after cardiac injury is p53 dependent(a–c) p53 immunostaining in Col1a2CreERT:R26RtdTomato and Col1a2CreERT:R26RtdTomato:p53CKO hearts (arrowheads) and (c) quantification of p53 expression in labeled fibroblasts (* p<0.005). (d–f) VECAD immunostaining in labeled fibroblasts (arrowheads) and (f) Labeled fibroblasts(%) expressing VECAD (* p<0.005). (g) Number of endothelial cells/high power field (* p<0.005, n=5 animals) (h,i) Cardiac function prior to and 7 days after injury. (*p<0.05, n=9 animals). (j) Masson’s Trichrome staining 14 days after injury. (k) Quantitation of fibrosis (* p<0.05). (n=4 animals unless mentioned, All graphs show mean±S.E.M., scale bar: 10μm).
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Figure 3: MEndoT after cardiac injury is p53 dependent(a–c) p53 immunostaining in Col1a2CreERT:R26RtdTomato and Col1a2CreERT:R26RtdTomato:p53CKO hearts (arrowheads) and (c) quantification of p53 expression in labeled fibroblasts (* p<0.005). (d–f) VECAD immunostaining in labeled fibroblasts (arrowheads) and (f) Labeled fibroblasts(%) expressing VECAD (* p<0.005). (g) Number of endothelial cells/high power field (* p<0.005, n=5 animals) (h,i) Cardiac function prior to and 7 days after injury. (*p<0.05, n=9 animals). (j) Masson’s Trichrome staining 14 days after injury. (k) Quantitation of fibrosis (* p<0.05). (n=4 animals unless mentioned, All graphs show mean±S.E.M., scale bar: 10μm).
Mentions: To determine whether p53 mediates MEndoT in vivo, we subjected Col1a2CreERT:R26RtdTomato:p53fl/fl mice to ischemic cardiac injury 5 days following cessation of tamoxifen. Mice with intact p53 exhibited 6±0.64 fold increase (mean±S.E.M.) in cardiac fibroblast p53 levels 3 days after cardiac injury, but in mice with fibroblast specific p53 deletion [referred to as Col1a2CreERT:R26RtdTomato:p53CKO (conditional knock out)], the mean p53 expression in border zone cardiac fibroblasts failed to increase significantly (Fig. 3a–c). The degree of MEndoT at 3 days post-injury in Col1a2CreERT:R26RtdTomato:p53CKO animals decreased by 57% (Fig. 3d–f) and was associated with a decrease in capillary density in the injury region (Fig. 3g). Increase in vessel density in the injured heart is a critical post-ischemic repair mechanism. Diminished neovascularization can lead to rapid decline in cardiac function after cardiac injury and is associated with worsened scarring34. Echocardiography on hearts of mice 7 days after cardiac injury showed significant worsening of cardiac function in p53CKO mice (Fig. 3h,i). Masson Trichrome staining demonstrated a greater amount of collagen deposition in the hearts of Col1a2CreERT:R26RtdTomato:p53CKO animals (Fig. 3j,k). The degree of inflammatory infiltrate measured by the number of CD68 expressing macrophages was also significantly higher in the Col1a2CreERT:R26RtdTomato:p53CKO animals (Extended Data Fig. 9a,b,d). These observations demonstrate that p53 is necessary for MEndoT to occur after ischemic cardiac injury and that disruption of MEndoT is associated with diminished post-injury vascularity and cardiac function.

Bottom Line: We show that the transcription factor p53 regulates such a switch in cardiac fibroblast fate.Loss of p53 in cardiac fibroblasts severely decreases the formation of fibroblast-derived endothelial cells, reduces post-infarct vascular density and worsens cardiac function.These observations demonstrate that mesenchymal-to-endothelial transition contributes to neovascularization of the injured heart and represents a potential therapeutic target for enhancing cardiac repair.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology &Physiology, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599, USA.

ABSTRACT
Endothelial cells contribute to a subset of cardiac fibroblasts by undergoing endothelial-to-mesenchymal transition, but whether cardiac fibroblasts can adopt an endothelial cell fate and directly contribute to neovascularization after cardiac injury is not known. Here, using genetic fate map techniques, we demonstrate that cardiac fibroblasts rapidly adopt an endothelial-cell-like phenotype after acute ischaemic cardiac injury. Fibroblast-derived endothelial cells exhibit anatomical and functional characteristics of native endothelial cells. We show that the transcription factor p53 regulates such a switch in cardiac fibroblast fate. Loss of p53 in cardiac fibroblasts severely decreases the formation of fibroblast-derived endothelial cells, reduces post-infarct vascular density and worsens cardiac function. Conversely, stimulation of the p53 pathway in cardiac fibroblasts augments mesenchymal-to-endothelial transition, enhances vascularity and improves cardiac function. These observations demonstrate that mesenchymal-to-endothelial transition contributes to neovascularization of the injured heart and represents a potential therapeutic target for enhancing cardiac repair.

Show MeSH
Related in: MedlinePlus