Development of the mouse retinal vasculature: angiogenesis versus vasculogenesis.

PURPOSE The inner vasculature of the retina develops as a spreading network, which is preceded by spindle-shaped cells. These cells are alleged to be vascular precursor cells (angioblasts). This study was designed to test whether such angioblasts exist in neonatal mouse retina. METHODS In situ hybridization and immunohistochemistry on mouse retinal wholemount preparations were used to visualize specific vascular cell types. RESULTS In situ hybridization with an RNA probe against vascular endothelial growth factor receptor (VEGFR)-2 (a marker for endothelial cells and angioblasts) labeled the vascular network but failed to label the spindle-shaped cells in front of it. A probe against VEGFR1, a marker for endothelial cells only, revealed the same staining pattern. Pericytes, visualized with a probe against platelet-derived growth receptor (PDGFR)-beta, were spread over the entire vessel network, but not beyond it. However, in situ hybridization with a probe against PDGFRalpha (a marker for retinal astrocytes) labeled spindle-shaped cells preceding the vessel network. CONCLUSIONS These observations imply that in the mouse retina the spindle-shaped cells preceding the forming vasculature are immature retinal astrocytes and not vascular precursor cells and that the primary vascular network in the retina develops by angiogenesis (budding from existing vessels) and not vasculogenesis (assembly of dispersed angioblasts).

[1]  S. Nishikawa,et al.  PDGF Mediates a Neuron–Astrocyte Interaction in the Developing Retina , 1996, Neuron.

[2]  D. Cogan,et al.  Accessory cells in vessels of the paranatal human retina. , 1986, Archives of ophthalmology.

[3]  N. Ashton,et al.  Retinal angiogenesis in the human embryo. , 1970, British medical bulletin.

[4]  J. Stone,et al.  Development of retinal vasculature is mediated by hypoxia-induced vascular endothelial growth factor (VEGF) expression by neuroglia , 1995, The Journal of neuroscience : the official journal of the Society for Neuroscience.

[5]  R W Flower,et al.  Postnatal retinal vascular development of the puppy. , 1985, Investigative ophthalmology & visual science.

[6]  J. Stone,et al.  Origin of retinal astrocytes in the rat: Evidence of migration from the optic nerve , 1989, The Journal of comparative neurology.

[7]  R. Engerman,et al.  Development of retinal vasculature in rats. , 1965, American journal of ophthalmology.

[8]  V. Wallace,et al.  Expression of Sonic hedgehog and its putative role as a precursor cell mitogen in the developing mouse retina. , 1997, Development.

[9]  A. Hendrickson,et al.  Immunohistochemical characterization of developing and mature primate retinal blood vessels. , 1996, Investigative ophthalmology & visual science.

[10]  R. Caldwell,et al.  Astrocytes modulate retinal vasculogenesis: Effects on endothelial cell differentiation , 1995, Glia.

[11]  R W Flower,et al.  Visualization of a developing vasculature. , 1987, Microvascular research.

[12]  A. Ullrich,et al.  Flk-1 expression defines a population of early embryonic hematopoietic precursors. , 1997, Development.

[13]  Janet Rossant,et al.  Failure of blood-island formation and vasculogenesis in Flk-1-deficient mice , 1995, Nature.

[14]  C. Betsholtz,et al.  Role of PDGF-B and PDGFR-beta in recruitment of vascular smooth muscle cells and pericytes during embryonic blood vessel formation in the mouse. , 1999, Development.

[15]  E. Keshet,et al.  A plasticity window for blood vessel remodelling is defined by pericyte coverage of the preformed endothelial network and is regulated by PDGF-B and VEGF. , 1998, Development.

[16]  B R Johansson,et al.  Pericyte loss and microaneurysm formation in PDGF-B-deficient mice. , 1997, Science.

[17]  D. Hunter,et al.  Vitamin E protects against retinopathy of prematurity through action on spindle cells , 1984, Nature.

[18]  L. Smith,et al.  Characterization of vascular development in the mouse retina. , 1988, Microvascular research.

[19]  R. Caldwell,et al.  Astrocytes modulate retinal vasculogenesis: effects on fibronectin expression. , 1994, Journal of cell science.

[20]  J. Provis,et al.  Astrocyte proliferation during development of the human retinal vasculature. , 1999, Experimental eye research.

[21]  S. Nishikawa,et al.  Progressive lineage analysis by cell sorting and culture identifies FLK1+VE-cadherin+ cells at a diverging point of endothelial and hemopoietic lineages. , 1998, Development.

[22]  J. Stone,et al.  Development of retinal vasculature in the cat: processes and mechanisms. , 1990, Current eye research.

[23]  R. Janzer,et al.  Astrocytes induce blood–brain barrier properties in endothelial cells , 1987, Nature.

[24]  J. Stone,et al.  Relationship between astrocytes, ganglion cells and vasculature of the retina , 1987, The Journal of comparative neurology.

[25]  W. Risau,et al.  Mechanisms of angiogenesis , 1997, Nature.

[26]  M. Kennedy,et al.  A common precursor for hematopoietic and endothelial cells. , 1998, Development.

[27]  J. Rossant,et al.  Role of the Flt-1 receptor tyrosine kinase in regulating the assembly of vascular endothelium , 1995, Nature.

[28]  J. Rossant,et al.  flk-1, an flt-related receptor tyrosine kinase is an early marker for endothelial cell precursors. , 1993, Development.

[29]  T. Quinn,et al.  Fetal liver kinase 1 is a receptor for vascular endothelial growth factor and is selectively expressed in vascular endothelium. , 1993, Proceedings of the National Academy of Sciences of the United States of America.

[30]  T. Chan-Ling,et al.  Vascularization of the human fetal retina: roles of vasculogenesis and angiogenesis. , 2000, Investigative ophthalmology & visual science.

[31]  A. Hendrickson,et al.  Vascular development in primate retina: comparison of laminar plexus formation in monkey and human. , 1994, Investigative ophthalmology & visual science.

[32]  L. F. de Oliveira,et al.  Development of retinal vessels in the rat. , 1967, Investigative ophthalmology.

[33]  A. Ullrich,et al.  High affinity VEGF binding and developmental expression suggest Flk-1 as a major regulator of vasculogenesis and angiogenesis , 1993, Cell.

[34]  W. Richardson,et al.  PDGF and its receptors in the developing rodent retina and optic nerve. , 1993, Development.