Pericytes of newly formed vessels in experimental subretinal neovascularization
T. Ishibashi, H. Inomata, T. Sakamoto and S. J. Ryan
Department of Ophthalmology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
OBJECTIVE: To examine the role of pericytes in the progression of
subretinal neovascularization in a primate model. METHODS: Subretinal
neovascularization was induced by intense laser photocoagulation in four
monkey eyes. Single eyes were enucleated at 3, 7, 14, and 21 days after
photocoagulation and were studied with light and electron microscopy.
RESULTS: Three days after photocoagulation, newly formed vessels were
observed in the choroid and subretinal space. Although most of these
vessels had an immature appearance and consisted only of endothelial cells
that formed narrow lumens, mitotic figures of pericytes were occasionally
found near the endothelial cells. Seven days after photocoagulation, all of
the newly formed vessels possessed pericytes. Fourteen days after
photocoagulation, many vessels appeared to be mature. Many sites of
pericyte-endothelial cell contact were observed. These contacts were
composed of cytoplasmic interdigitation and membrane apposition. By 21 days
after photocoagulation, the mature vessels had increased in number, and the
endothelial cells had many fenestrations with diaphragms. The pericyte
coverage of the endothelial cells was less at this stage than at 14 days
after photocoagulation, and sites of pericyte-endothelial cell contacts
were observed only rarely. CONCLUSION: Pericytes are involved in maturation
of the endothelial cells that form subretinal new vessels.
