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Lymphangiogenesis and angiogenesis during human fetal pancreas development.

Roost MS, van Iperen L, de Melo Bernardo A, Mummery CL, Carlotti F, de Koning EJ, Chuva de Sousa Lopes SM - (2014)

Bottom Line: Whilst lymphatic vessels did not directly intrude the islets of Langerhans, three-dimensional reconstruction revealed that they were present in the vicinity of islets of Langerhans between W17-W22.Our data suggest that the blood and lymphatic machinery in the human pancreas is in place to support endocrine function from W17-W22 onwards.Our study provides the first systematic assessment of the progression of lymphangiogenesis during human pancreatic development.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy and Embryology, Leiden University Medical Center, Einthovenweg 20, 2333 ZC Leiden, The Netherlands.

ABSTRACT

Background: The complex endocrine and exocrine functionality of the human pancreas depends on an efficient fluid transport through the blood and the lymphatic vascular systems. The lymphatic vasculature has key roles in the physiology of the pancreas and in regulating the immune response, both important for developing successful transplantation and cell-replacement therapies to treat diabetes. However, little is known about how the lymphatic and blood systems develop in humans. Here, we investigated the establishment of these two vascular systems in human pancreas organogenesis in order to understand neovascularization in the context of emerging regenerative therapies.

Methods: We examined angiogenesis and lymphangiogenesis during human pancreas development between 9 and 22 weeks of gestation (W9-W22) by immunohistochemistry.

Results: As early as W9, the peri-pancreatic mesenchyme was populated by CD31-expressing blood vessels as well as LYVE1- and PDPN-expressing lymphatic vessels. The appearance of smooth muscle cell-coated blood vessels in the intra-pancreatic mesenchyme occurred only several weeks later and from W14.5 onwards the islets of Langerhans also became heavily irrigated by blood vessels. In contrast to blood vessels, LYVE1- and PDPN-expressing lymphatic vessels were restricted to the peri-pancreatic mesenchyme until later in development (W14.5-W17), and some of these invading lymphatic vessels contained smooth muscle cells at W17. Interestingly, between W11-W22, most large caliber lymphatic vessels were lined with a characteristic, discontinuous, collagen type IV-rich basement membrane. Whilst lymphatic vessels did not directly intrude the islets of Langerhans, three-dimensional reconstruction revealed that they were present in the vicinity of islets of Langerhans between W17-W22.

Conclusion: Our data suggest that the blood and lymphatic machinery in the human pancreas is in place to support endocrine function from W17-W22 onwards. Our study provides the first systematic assessment of the progression of lymphangiogenesis during human pancreatic development.

No MeSH data available.


Related in: MedlinePlus

Lymphangiogenesis during human pancreatic development. (A) Pancreas at W9 immunostained for CK19 and LYVE1. White arrows point to LYVE1-positive lymphatic vessels. White line shows the separation between the peri-pancreatic mesenchyme (PPM) and intra-pancreatic mesenchyme (IPM). (B) Pancreas at W11 immunostained for CK19 and podoplanin (PDPN). White arrows point to PDPN-positive lymphatic vessels. (C) Pancreata at W14.5, W17, W19 and W21 immunostained for CK19 and LYVE1. (D) Pancreata at W14.5, W17, W19 and W21 immunostained for CK19 and PDPN. Note that autofluorescent red blood cells, as yellow/orange dots, are present in in all images. Scale bars: 50 μm.
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Fig3: Lymphangiogenesis during human pancreatic development. (A) Pancreas at W9 immunostained for CK19 and LYVE1. White arrows point to LYVE1-positive lymphatic vessels. White line shows the separation between the peri-pancreatic mesenchyme (PPM) and intra-pancreatic mesenchyme (IPM). (B) Pancreas at W11 immunostained for CK19 and podoplanin (PDPN). White arrows point to PDPN-positive lymphatic vessels. (C) Pancreata at W14.5, W17, W19 and W21 immunostained for CK19 and LYVE1. (D) Pancreata at W14.5, W17, W19 and W21 immunostained for CK19 and PDPN. Note that autofluorescent red blood cells, as yellow/orange dots, are present in in all images. Scale bars: 50 μm.

Mentions: From W9 to about W14.5-W17, LYVE1-positive and PDPN-positive small lymphatic vessels were present exclusively in the PPM (Figure 3A and B, white arrows). However, LYVE1, but not PDPN, is also known to be expressed by both CD68-positive and F4/80-positive macrophages [44–46], and those were present as CD68-positive and LYVE1-positive single cells in both the PPM and IPM throughout development (Additional file 1: Figure S1A). By W17, LYVE1-positive and PDPN-positive lymphatic larger caliber vessels were visible in both the PPM and IPM (Figure 3C and D, white arrows), but were rarely or not observed penetrating the intralobular region containing the epithelial-derived tissue (the developing acinar or ductal structures and the islets of Langerhans). The first few amylase-positive acinar cells were observed at W14.5 (Additional file 1: Figure S1B), the stage when lymphatic vessels start to colonize the IPM. However, we did not observe any direct association of lymphatic vessels with amylase-positive cells until W22 either (Additional file 1: Figure S1B).Figure 3


Lymphangiogenesis and angiogenesis during human fetal pancreas development.

Roost MS, van Iperen L, de Melo Bernardo A, Mummery CL, Carlotti F, de Koning EJ, Chuva de Sousa Lopes SM - (2014)

Lymphangiogenesis during human pancreatic development. (A) Pancreas at W9 immunostained for CK19 and LYVE1. White arrows point to LYVE1-positive lymphatic vessels. White line shows the separation between the peri-pancreatic mesenchyme (PPM) and intra-pancreatic mesenchyme (IPM). (B) Pancreas at W11 immunostained for CK19 and podoplanin (PDPN). White arrows point to PDPN-positive lymphatic vessels. (C) Pancreata at W14.5, W17, W19 and W21 immunostained for CK19 and LYVE1. (D) Pancreata at W14.5, W17, W19 and W21 immunostained for CK19 and PDPN. Note that autofluorescent red blood cells, as yellow/orange dots, are present in in all images. Scale bars: 50 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4362646&req=5

Fig3: Lymphangiogenesis during human pancreatic development. (A) Pancreas at W9 immunostained for CK19 and LYVE1. White arrows point to LYVE1-positive lymphatic vessels. White line shows the separation between the peri-pancreatic mesenchyme (PPM) and intra-pancreatic mesenchyme (IPM). (B) Pancreas at W11 immunostained for CK19 and podoplanin (PDPN). White arrows point to PDPN-positive lymphatic vessels. (C) Pancreata at W14.5, W17, W19 and W21 immunostained for CK19 and LYVE1. (D) Pancreata at W14.5, W17, W19 and W21 immunostained for CK19 and PDPN. Note that autofluorescent red blood cells, as yellow/orange dots, are present in in all images. Scale bars: 50 μm.
Mentions: From W9 to about W14.5-W17, LYVE1-positive and PDPN-positive small lymphatic vessels were present exclusively in the PPM (Figure 3A and B, white arrows). However, LYVE1, but not PDPN, is also known to be expressed by both CD68-positive and F4/80-positive macrophages [44–46], and those were present as CD68-positive and LYVE1-positive single cells in both the PPM and IPM throughout development (Additional file 1: Figure S1A). By W17, LYVE1-positive and PDPN-positive lymphatic larger caliber vessels were visible in both the PPM and IPM (Figure 3C and D, white arrows), but were rarely or not observed penetrating the intralobular region containing the epithelial-derived tissue (the developing acinar or ductal structures and the islets of Langerhans). The first few amylase-positive acinar cells were observed at W14.5 (Additional file 1: Figure S1B), the stage when lymphatic vessels start to colonize the IPM. However, we did not observe any direct association of lymphatic vessels with amylase-positive cells until W22 either (Additional file 1: Figure S1B).Figure 3

Bottom Line: Whilst lymphatic vessels did not directly intrude the islets of Langerhans, three-dimensional reconstruction revealed that they were present in the vicinity of islets of Langerhans between W17-W22.Our data suggest that the blood and lymphatic machinery in the human pancreas is in place to support endocrine function from W17-W22 onwards.Our study provides the first systematic assessment of the progression of lymphangiogenesis during human pancreatic development.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy and Embryology, Leiden University Medical Center, Einthovenweg 20, 2333 ZC Leiden, The Netherlands.

ABSTRACT

Background: The complex endocrine and exocrine functionality of the human pancreas depends on an efficient fluid transport through the blood and the lymphatic vascular systems. The lymphatic vasculature has key roles in the physiology of the pancreas and in regulating the immune response, both important for developing successful transplantation and cell-replacement therapies to treat diabetes. However, little is known about how the lymphatic and blood systems develop in humans. Here, we investigated the establishment of these two vascular systems in human pancreas organogenesis in order to understand neovascularization in the context of emerging regenerative therapies.

Methods: We examined angiogenesis and lymphangiogenesis during human pancreas development between 9 and 22 weeks of gestation (W9-W22) by immunohistochemistry.

Results: As early as W9, the peri-pancreatic mesenchyme was populated by CD31-expressing blood vessels as well as LYVE1- and PDPN-expressing lymphatic vessels. The appearance of smooth muscle cell-coated blood vessels in the intra-pancreatic mesenchyme occurred only several weeks later and from W14.5 onwards the islets of Langerhans also became heavily irrigated by blood vessels. In contrast to blood vessels, LYVE1- and PDPN-expressing lymphatic vessels were restricted to the peri-pancreatic mesenchyme until later in development (W14.5-W17), and some of these invading lymphatic vessels contained smooth muscle cells at W17. Interestingly, between W11-W22, most large caliber lymphatic vessels were lined with a characteristic, discontinuous, collagen type IV-rich basement membrane. Whilst lymphatic vessels did not directly intrude the islets of Langerhans, three-dimensional reconstruction revealed that they were present in the vicinity of islets of Langerhans between W17-W22.

Conclusion: Our data suggest that the blood and lymphatic machinery in the human pancreas is in place to support endocrine function from W17-W22 onwards. Our study provides the first systematic assessment of the progression of lymphangiogenesis during human pancreatic development.

No MeSH data available.


Related in: MedlinePlus