Limits...
Endocardial tip cells in the human embryo - facts and hypotheses.

Rusu MC, Poalelungi CV, Vrapciu AD, Nicolescu MI, Hostiuc S, Mogoanta L, Taranu T - PLoS ONE (2015)

Bottom Line: Subepicardial vessels were found branching into the outer ventricular myocardium, with a pattern of recruiting α-SMA+/desmin+ vascular smooth muscle cells and pericytes.Within the inner myocardium, we found endothelial networks rooted from endocardium, guided by filopodia-projecting CD31+/CD34+/CD105+/ vimentin+ endocardial tip cells.Nevertheless, endocardial tip cells were also found in cardiac cushions, but they were not related to cushion endothelial networks.

View Article: PubMed Central - PubMed

Affiliation: Division of Anatomy, Faculty of Dental Medicine, "Carol Davila" University of Medicine and Pharmacy, Bucharest, Romania; MEDCENTER-Center of Excellence in Laboratory Medicine and Pathology, Bucharest, Romania.

ABSTRACT
Experimental studies regarding coronary embryogenesis suggest that the endocardium is a source of endothelial cells for the myocardial networks. As this was not previously documented in human embryos, we aimed to study whether or not endothelial tip cells could be correlated with endocardial-dependent mechanisms of sprouting angiogenesis. Six human embryos (43-56 days) were obtained and processed in accordance with ethical regulations; immunohistochemistry was performed for CD105 (endoglin), CD31, CD34, α-smooth muscle actin, desmin and vimentin antibodies. Primitive main vessels were found deriving from both the sinus venosus and aorta, and were sought to be the primordia of the venous and arterial ends of cardiac microcirculation. Subepicardial vessels were found branching into the outer ventricular myocardium, with a pattern of recruiting α-SMA+/desmin+ vascular smooth muscle cells and pericytes. Endothelial sprouts were guided by CD31+/CD34+/CD105+/vimentin+ endothelial tip cells. Within the inner myocardium, we found endothelial networks rooted from endocardium, guided by filopodia-projecting CD31+/CD34+/CD105+/ vimentin+ endocardial tip cells. The myocardial microcirculatory bed in the atria was mostly originated from endocardium, as well. Nevertheless, endocardial tip cells were also found in cardiac cushions, but they were not related to cushion endothelial networks. A general anatomical pattern of cardiac microvascular embryogenesis was thus hypothesized; the arterial and venous ends being linked, respectively, to the aorta and sinus venosus. Further elongation of the vessels may be related to the epicardium and subepicardial stroma and the intramyocardial network, depending on either endothelial and endocardial filopodia-guided tip cells in ventricles, or mostly on endocardium, in atria.

No MeSH data available.


Human embryonic heart (48 days), CD 34 and CD 31 immune labeling.Oblique sagittal cut of a 48 days human embryonic heart. Immune labeling of successive slides with CD34 (A, B) and CD31 (C, D) antibodies (1, 1’.atrioventricular cushions; 2.ventricle; 3.primitive atrium; 4.sinus venosus; 5.coronary sinus; 6. endocardial-derived endothelial network in the ventricular wall); insets depict filopodia-projecting endocardial tip cells of the sinus venosus wall (B) and ventricular wall (D). CD105-positive epicardially-derived endothelial tubes (arrows) and intramyocardial endothelia (arrowheads) are indicated in (E). A continuous desmin-positive reaction is identified (F) in the epicardium (arrowheads), but not intramyocardially. Vimentin labeled (G) both the endocardial endothelia (arrow) and the epicardial stroma (arrowhead). Subepicardial vessels are coated by α-SMA-positive pericytes (H, inset, arrows).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4305311&req=5

pone.0115853.g004: Human embryonic heart (48 days), CD 34 and CD 31 immune labeling.Oblique sagittal cut of a 48 days human embryonic heart. Immune labeling of successive slides with CD34 (A, B) and CD31 (C, D) antibodies (1, 1’.atrioventricular cushions; 2.ventricle; 3.primitive atrium; 4.sinus venosus; 5.coronary sinus; 6. endocardial-derived endothelial network in the ventricular wall); insets depict filopodia-projecting endocardial tip cells of the sinus venosus wall (B) and ventricular wall (D). CD105-positive epicardially-derived endothelial tubes (arrows) and intramyocardial endothelia (arrowheads) are indicated in (E). A continuous desmin-positive reaction is identified (F) in the epicardium (arrowheads), but not intramyocardially. Vimentin labeled (G) both the endocardial endothelia (arrow) and the epicardial stroma (arrowhead). Subepicardial vessels are coated by α-SMA-positive pericytes (H, inset, arrows).

Mentions: In late stage embryos (6–8 weeks), the aortic sinuses beneath the aortic cushions were found sending off a number of arteries that penetrated the subepicardium and the outer myocardium further; where they were dichotomizing (Fig. 3). The coronary sinus was identified leaving the sinus venosus and branching into the crista terminalis and the inferior surface of the ventricle (Fig. 4). Endocardial and vascular endothelia were CD31+/CD34+/CD105+/vimentin+ (Fig. 4) and featured filopodia-projecting endothelial cells. Apparently, a rich endothelial network was supplied by the endocardial endothelium within the inner myocardium (Fig. 4). The outer part of the myocardium was supplied by stromal-embedded subepicardial vessels (Figs. 4 and 5), that were sending myocardial branches involved in active processes of sprouting, as proved by ETCs. Within the subepicardium α-SMA+/desmin+ myoid coats of the endothelial tubes were found (Figs. 4and5). In the outer part of the myocardium, α-SMA+/desmin+ cells were apposed to the endothelial sprouts (Fig. 5).


Endocardial tip cells in the human embryo - facts and hypotheses.

Rusu MC, Poalelungi CV, Vrapciu AD, Nicolescu MI, Hostiuc S, Mogoanta L, Taranu T - PLoS ONE (2015)

Human embryonic heart (48 days), CD 34 and CD 31 immune labeling.Oblique sagittal cut of a 48 days human embryonic heart. Immune labeling of successive slides with CD34 (A, B) and CD31 (C, D) antibodies (1, 1’.atrioventricular cushions; 2.ventricle; 3.primitive atrium; 4.sinus venosus; 5.coronary sinus; 6. endocardial-derived endothelial network in the ventricular wall); insets depict filopodia-projecting endocardial tip cells of the sinus venosus wall (B) and ventricular wall (D). CD105-positive epicardially-derived endothelial tubes (arrows) and intramyocardial endothelia (arrowheads) are indicated in (E). A continuous desmin-positive reaction is identified (F) in the epicardium (arrowheads), but not intramyocardially. Vimentin labeled (G) both the endocardial endothelia (arrow) and the epicardial stroma (arrowhead). Subepicardial vessels are coated by α-SMA-positive pericytes (H, inset, arrows).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4305311&req=5

pone.0115853.g004: Human embryonic heart (48 days), CD 34 and CD 31 immune labeling.Oblique sagittal cut of a 48 days human embryonic heart. Immune labeling of successive slides with CD34 (A, B) and CD31 (C, D) antibodies (1, 1’.atrioventricular cushions; 2.ventricle; 3.primitive atrium; 4.sinus venosus; 5.coronary sinus; 6. endocardial-derived endothelial network in the ventricular wall); insets depict filopodia-projecting endocardial tip cells of the sinus venosus wall (B) and ventricular wall (D). CD105-positive epicardially-derived endothelial tubes (arrows) and intramyocardial endothelia (arrowheads) are indicated in (E). A continuous desmin-positive reaction is identified (F) in the epicardium (arrowheads), but not intramyocardially. Vimentin labeled (G) both the endocardial endothelia (arrow) and the epicardial stroma (arrowhead). Subepicardial vessels are coated by α-SMA-positive pericytes (H, inset, arrows).
Mentions: In late stage embryos (6–8 weeks), the aortic sinuses beneath the aortic cushions were found sending off a number of arteries that penetrated the subepicardium and the outer myocardium further; where they were dichotomizing (Fig. 3). The coronary sinus was identified leaving the sinus venosus and branching into the crista terminalis and the inferior surface of the ventricle (Fig. 4). Endocardial and vascular endothelia were CD31+/CD34+/CD105+/vimentin+ (Fig. 4) and featured filopodia-projecting endothelial cells. Apparently, a rich endothelial network was supplied by the endocardial endothelium within the inner myocardium (Fig. 4). The outer part of the myocardium was supplied by stromal-embedded subepicardial vessels (Figs. 4 and 5), that were sending myocardial branches involved in active processes of sprouting, as proved by ETCs. Within the subepicardium α-SMA+/desmin+ myoid coats of the endothelial tubes were found (Figs. 4and5). In the outer part of the myocardium, α-SMA+/desmin+ cells were apposed to the endothelial sprouts (Fig. 5).

Bottom Line: Subepicardial vessels were found branching into the outer ventricular myocardium, with a pattern of recruiting α-SMA+/desmin+ vascular smooth muscle cells and pericytes.Within the inner myocardium, we found endothelial networks rooted from endocardium, guided by filopodia-projecting CD31+/CD34+/CD105+/ vimentin+ endocardial tip cells.Nevertheless, endocardial tip cells were also found in cardiac cushions, but they were not related to cushion endothelial networks.

View Article: PubMed Central - PubMed

Affiliation: Division of Anatomy, Faculty of Dental Medicine, "Carol Davila" University of Medicine and Pharmacy, Bucharest, Romania; MEDCENTER-Center of Excellence in Laboratory Medicine and Pathology, Bucharest, Romania.

ABSTRACT
Experimental studies regarding coronary embryogenesis suggest that the endocardium is a source of endothelial cells for the myocardial networks. As this was not previously documented in human embryos, we aimed to study whether or not endothelial tip cells could be correlated with endocardial-dependent mechanisms of sprouting angiogenesis. Six human embryos (43-56 days) were obtained and processed in accordance with ethical regulations; immunohistochemistry was performed for CD105 (endoglin), CD31, CD34, α-smooth muscle actin, desmin and vimentin antibodies. Primitive main vessels were found deriving from both the sinus venosus and aorta, and were sought to be the primordia of the venous and arterial ends of cardiac microcirculation. Subepicardial vessels were found branching into the outer ventricular myocardium, with a pattern of recruiting α-SMA+/desmin+ vascular smooth muscle cells and pericytes. Endothelial sprouts were guided by CD31+/CD34+/CD105+/vimentin+ endothelial tip cells. Within the inner myocardium, we found endothelial networks rooted from endocardium, guided by filopodia-projecting CD31+/CD34+/CD105+/ vimentin+ endocardial tip cells. The myocardial microcirculatory bed in the atria was mostly originated from endocardium, as well. Nevertheless, endocardial tip cells were also found in cardiac cushions, but they were not related to cushion endothelial networks. A general anatomical pattern of cardiac microvascular embryogenesis was thus hypothesized; the arterial and venous ends being linked, respectively, to the aorta and sinus venosus. Further elongation of the vessels may be related to the epicardium and subepicardial stroma and the intramyocardial network, depending on either endothelial and endocardial filopodia-guided tip cells in ventricles, or mostly on endocardium, in atria.

No MeSH data available.