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Regression and persistence: remodelling in a tissue engineered axial vascular assembly.

Polykandriotis E, Euler S, Arkudas A, Pryymachuk G, Beier JP, Greil P, Dragu A, Lametschwandtner A, Kneser U, Horch RE - J. Cell. Mol. Med. (2009)

Bottom Line: After the fourth week the absolute number of vessels within the ROI decreased (P < 0.03) whereas, on the contrary, the fractional area of all segments increased (P < 0.02).The variance in calibre was significantly increased in the 8-week group (P < 0.05).Phenomena of remodelling were evaluated quantitatively in a neovascular network and variance could be proposed as a parameter of net vascular maturation.

View Article: PubMed Central - PubMed

Affiliation: Department of Plastic and Hand Surgery, University of Erlangen, Erlangen, Germany. elias.polykandriotis@uk-erlangen.de

ABSTRACT
In later stages of vasculoangiogenesis a vascular network is going through a metamorphosis for optimal perfusion and economy of energy. In this study we make a quantitative approach to phenomena of remodelling in a bioartificial neovascular network and suggest variance of calibre as a parameter of neovascular maturation. For this study, 18 male Lewis rats were subjected to the AV loop operation in combination with a hard porous biogenic matrix and an isolation chamber. The animals were allocated into three groups for different explantation intervals set to 2, 4 and 8 weeks, respectively. Collective attributes like vascular density, percent fractional area and variance of calibre were evaluated for a predefined region of interest (ROI). Late morphogenesis was evaluated by means of scanning electron microscopy. After the fourth week the absolute number of vessels within the ROI decreased (P < 0.03) whereas, on the contrary, the fractional area of all segments increased (P < 0.02). The variance in calibre was significantly increased in the 8-week group (P < 0.05). Lymphatic growth after week 4, early pericyte migration as well as intussusceptive angiogenesis were identified immunohistologically. Phenomena of remodelling were evaluated quantitatively in a neovascular network and variance could be proposed as a parameter of net vascular maturation.

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(A) and (B) Serial sections of a 2-week specimen. (A) In the middle of the image, a neovascular ‘tripode’ (arrow) with PCT (red staining) encircling the endothelial formation (blue staining of nuclei) shows no India ink filling. On the right side (B) the formation shows clearly endothelial staining positive for lectin, with still no India ink filling. This finding is indicative of a vessel furnished with PCT prior to formation of its lumen. Because lumen formation is a relatively early phenomenon of angiogenesis, it seems like pericytic migration and endothelial proliferation are parallel mechanisms, as postulated recently (see text). 4a: α-SM actin, ×350; 4b: lectin; serial sections. (C) and (D) Non-sprouting angiogenesis by means of intussusceptive microvascular growth (IMG) is an efficient modus for expansion of a neovascular network. In this process a vessel is divided into two vessels by ingrowth (intussusception) of an interstitial pillar. On the right side (D) this process is demonstrated on a microvascular replica under the scanning electron microscope. If these pillars are of endothelial or fibroblastic origin is not fully understood. Asterisk: Early stage; Arrow advanced stage showing formation of a new vascular conduit. On the left side (C) a venuole is interrupted by an endothelial bridge at the asterisk. One could assume that intussusception is a phenomenon carried out by the endothelial cells; however, remodelling of angiogenesis is grossly a three-dimensional process and is best demonstrated by three-dimensional methods. 3c: (α-SM actin, ×200); 3d: SEM of corrosion casts, ×230.
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fig03: (A) and (B) Serial sections of a 2-week specimen. (A) In the middle of the image, a neovascular ‘tripode’ (arrow) with PCT (red staining) encircling the endothelial formation (blue staining of nuclei) shows no India ink filling. On the right side (B) the formation shows clearly endothelial staining positive for lectin, with still no India ink filling. This finding is indicative of a vessel furnished with PCT prior to formation of its lumen. Because lumen formation is a relatively early phenomenon of angiogenesis, it seems like pericytic migration and endothelial proliferation are parallel mechanisms, as postulated recently (see text). 4a: α-SM actin, ×350; 4b: lectin; serial sections. (C) and (D) Non-sprouting angiogenesis by means of intussusceptive microvascular growth (IMG) is an efficient modus for expansion of a neovascular network. In this process a vessel is divided into two vessels by ingrowth (intussusception) of an interstitial pillar. On the right side (D) this process is demonstrated on a microvascular replica under the scanning electron microscope. If these pillars are of endothelial or fibroblastic origin is not fully understood. Asterisk: Early stage; Arrow advanced stage showing formation of a new vascular conduit. On the left side (C) a venuole is interrupted by an endothelial bridge at the asterisk. One could assume that intussusception is a phenomenon carried out by the endothelial cells; however, remodelling of angiogenesis is grossly a three-dimensional process and is best demonstrated by three-dimensional methods. 3c: (α-SM actin, ×200); 3d: SEM of corrosion casts, ×230.

Mentions: α-SMA positive PCT were present at all vascular conduits indicating migration of PCTs as soon as 2 weeks after initiation of angiogenesis (Fig. 2E). India Ink free lumina appeared in the 4- and 8-week specimens probably indicating presence of lymphatics. (Fig. 2F). On the contrary, there were indeed lumina positive for lectin, identifying them as vessels and positive for α-SMA without any visible lumen. This might indicate that pericyte migration takes place before or concomitantly to formation of a neovascular lumen (Fig. 3A and B).


Regression and persistence: remodelling in a tissue engineered axial vascular assembly.

Polykandriotis E, Euler S, Arkudas A, Pryymachuk G, Beier JP, Greil P, Dragu A, Lametschwandtner A, Kneser U, Horch RE - J. Cell. Mol. Med. (2009)

(A) and (B) Serial sections of a 2-week specimen. (A) In the middle of the image, a neovascular ‘tripode’ (arrow) with PCT (red staining) encircling the endothelial formation (blue staining of nuclei) shows no India ink filling. On the right side (B) the formation shows clearly endothelial staining positive for lectin, with still no India ink filling. This finding is indicative of a vessel furnished with PCT prior to formation of its lumen. Because lumen formation is a relatively early phenomenon of angiogenesis, it seems like pericytic migration and endothelial proliferation are parallel mechanisms, as postulated recently (see text). 4a: α-SM actin, ×350; 4b: lectin; serial sections. (C) and (D) Non-sprouting angiogenesis by means of intussusceptive microvascular growth (IMG) is an efficient modus for expansion of a neovascular network. In this process a vessel is divided into two vessels by ingrowth (intussusception) of an interstitial pillar. On the right side (D) this process is demonstrated on a microvascular replica under the scanning electron microscope. If these pillars are of endothelial or fibroblastic origin is not fully understood. Asterisk: Early stage; Arrow advanced stage showing formation of a new vascular conduit. On the left side (C) a venuole is interrupted by an endothelial bridge at the asterisk. One could assume that intussusception is a phenomenon carried out by the endothelial cells; however, remodelling of angiogenesis is grossly a three-dimensional process and is best demonstrated by three-dimensional methods. 3c: (α-SM actin, ×200); 3d: SEM of corrosion casts, ×230.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4496123&req=5

fig03: (A) and (B) Serial sections of a 2-week specimen. (A) In the middle of the image, a neovascular ‘tripode’ (arrow) with PCT (red staining) encircling the endothelial formation (blue staining of nuclei) shows no India ink filling. On the right side (B) the formation shows clearly endothelial staining positive for lectin, with still no India ink filling. This finding is indicative of a vessel furnished with PCT prior to formation of its lumen. Because lumen formation is a relatively early phenomenon of angiogenesis, it seems like pericytic migration and endothelial proliferation are parallel mechanisms, as postulated recently (see text). 4a: α-SM actin, ×350; 4b: lectin; serial sections. (C) and (D) Non-sprouting angiogenesis by means of intussusceptive microvascular growth (IMG) is an efficient modus for expansion of a neovascular network. In this process a vessel is divided into two vessels by ingrowth (intussusception) of an interstitial pillar. On the right side (D) this process is demonstrated on a microvascular replica under the scanning electron microscope. If these pillars are of endothelial or fibroblastic origin is not fully understood. Asterisk: Early stage; Arrow advanced stage showing formation of a new vascular conduit. On the left side (C) a venuole is interrupted by an endothelial bridge at the asterisk. One could assume that intussusception is a phenomenon carried out by the endothelial cells; however, remodelling of angiogenesis is grossly a three-dimensional process and is best demonstrated by three-dimensional methods. 3c: (α-SM actin, ×200); 3d: SEM of corrosion casts, ×230.
Mentions: α-SMA positive PCT were present at all vascular conduits indicating migration of PCTs as soon as 2 weeks after initiation of angiogenesis (Fig. 2E). India Ink free lumina appeared in the 4- and 8-week specimens probably indicating presence of lymphatics. (Fig. 2F). On the contrary, there were indeed lumina positive for lectin, identifying them as vessels and positive for α-SMA without any visible lumen. This might indicate that pericyte migration takes place before or concomitantly to formation of a neovascular lumen (Fig. 3A and B).

Bottom Line: After the fourth week the absolute number of vessels within the ROI decreased (P < 0.03) whereas, on the contrary, the fractional area of all segments increased (P < 0.02).The variance in calibre was significantly increased in the 8-week group (P < 0.05).Phenomena of remodelling were evaluated quantitatively in a neovascular network and variance could be proposed as a parameter of net vascular maturation.

View Article: PubMed Central - PubMed

Affiliation: Department of Plastic and Hand Surgery, University of Erlangen, Erlangen, Germany. elias.polykandriotis@uk-erlangen.de

ABSTRACT
In later stages of vasculoangiogenesis a vascular network is going through a metamorphosis for optimal perfusion and economy of energy. In this study we make a quantitative approach to phenomena of remodelling in a bioartificial neovascular network and suggest variance of calibre as a parameter of neovascular maturation. For this study, 18 male Lewis rats were subjected to the AV loop operation in combination with a hard porous biogenic matrix and an isolation chamber. The animals were allocated into three groups for different explantation intervals set to 2, 4 and 8 weeks, respectively. Collective attributes like vascular density, percent fractional area and variance of calibre were evaluated for a predefined region of interest (ROI). Late morphogenesis was evaluated by means of scanning electron microscopy. After the fourth week the absolute number of vessels within the ROI decreased (P < 0.03) whereas, on the contrary, the fractional area of all segments increased (P < 0.02). The variance in calibre was significantly increased in the 8-week group (P < 0.05). Lymphatic growth after week 4, early pericyte migration as well as intussusceptive angiogenesis were identified immunohistologically. Phenomena of remodelling were evaluated quantitatively in a neovascular network and variance could be proposed as a parameter of net vascular maturation.

Show MeSH
Related in: MedlinePlus