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Surgical brain injury causes neovascularization in the disrupted brain parenchyma, which occurs with the participation of endothelial-like cells. Differentiation of angioblasts from embryonic mesothelial cells has been proposed on the ground of biochemical and antigenic similarities between mesothelial and endothelial cells. Therefore, a transient localization of cytokeratin, the main mesothelial intermediate filament protein, to some embryonic vessels and endothelial progenitors, prompted us to use it to identify the source of cells participating in vessel formation after surgical brain injury. To determine the immunophenotypes of immature endothelial cells involved in new vessel formation following surgical rat brain injury, we used immunohistochemical and electron microscopic immunocytochemical techniques. Subcellular localization of protein markers: Flk-1, cytokeratin, and vimentin was examined in the cells investigated. Our results confirmed the existence of a diversity of immunophenotypes of immature endothelial cells in case of surgical-related brain injury.

Glial scar is formed following surgical damage to the cerebral cortex. In the present study we examined the ultrastructural status of the cerebral cortex 14 to 180 days following surgical damage to cerebral parenchyma. The results showed a contribution of astrocytes, but also mesodermal cells, to the process of scar formation. Furthermore, our study showed that the process initiated by trauma did not terminate with the formation of a glial scar. Late phases of repair following tissue damage were associated with lytic processes and a disassembly of the cerebral parenchyma. These findings indicate a changing and unstable nature of the glial scar and its components.

Objectives: We investigated neovasculatization in the cerebral cortex of the adult rat after surgical brain injury by ultrastructural, immunocytochemical and immunochemical means. Previously we described endothelial-like cell that participates in new vessel formation on plasma proteins that served as a provisional matrix in the region immediately adjacent to the traumatic injury. In the present study we describe new vessel formation in the multistep process with the alterations in endothelial-like cell immunophenotype., Method: The observations were conducted from 2 to 7 days after induction of cortical trauma. Traumatic injury was induced in the frontotemporal region of cerebral cortex., Results: We show that endothelial-like cell could not successfully terminate its development without the presence of pericyte and astrocyte. New formed blood vessels were accompanied by fibroblast and lipofibroblast cells differentiated probably from common progenitor., Main Findings: Our result suggests that endothelial-like cell is committed endothelial cell between progenitor endothelial cell and terminally differentiated endothelium stage. Therefore, we propose that our of endothelial stem cells present in blood at different stages of morphogenetic differentiation and specifically arrested in "check points" of development trauma mobilize the group of the most differentiated progenitors. These may contribute to new vessel formation., Conclusion: Our model should be useful for the characterization of endothelial commitment and endothelial cell differentiation after brain injury.

Postnatal neovascularization has been previously considered synonymous with angiogenesis but it was found that circulating endothelial progenitor cells may home into sites of neovascularization and their differentiation into endothelial cells is consistent with vasculogenesis. In this study, we investigated neovascularization of the adult rat's cerebral cortex after surgical brain injury by electron microscopic ultrastructural and immunocytochemical studies. We found places with disrupted brain parenchyma. The blood vessels showed an incomplete endothelial lining. In the brain parenchyma we observed fibrin, likely derived from disrupted blood vessels. In the plasma there were cell aggregates characterized by endothelial-like features with fibrils in the cytoplasm, untypical for endothelial cells. These endothelial-like cells participated in the process of new vessel formation. We used the anti-alpha(v) beta3 integrin antibody to visualize the different morphogenic stages of newly formed blood vessels. We demonstrated the relationship between alpha(v) beta3 integrin localization and different stages of new vessel formation. Our data suggest that growth and development of new blood vessels due to neovascularization following trauma of the adult rat brain are not restricted to angiogenesis but encompass vasculogenesis as well.

We investigated the features of newly formed blood vessels after surgical brain injury of the rat's cerebral cortex distal to the operated region. We document the process of split mature blood vessels by an endothelial bridge and morphological features of newly formed vessels. We did not observe a disruption of brain parenchyma. The endothelial lining in vessels was complete. The morphological features of the endothelial cells and basement membrane show that non-sprouting angiogenesis takes place distally to the surgical injury.

Objectives: Angiogenesis comprises two different mechanisms: endothelial sprouting and intussusceptive microvascular growth. The sprouting process is based on endothelial cell migration, proliferation and tube formation. Intussusceptive microvascular growth divides existing vessel lumens by formation and insertion of endothelial columns into the vessel lumen. The morphological features of microvessels of cerebral cortex and neurohypophysis were evaluated in a model of the cerebral traumatic injury., Method: The observations were conducted seven days after induction of cortical trauma. Traumatic injury was induced in the fronto-temporal region of cerebral cortex in general anesthesia with 20mg/kg ketamine hydrochloride., Results: Seven days after traumatic brain injury in sections from cerebral cortex and neurohypophysis we can observe morphological features of angiogenesis. Endothelium of the cerebral cortex possesses high endotheliocytes tightly connected and enveloped by amorphous basement membrane-like material. Transcapillary pillars tightly connected with neighbouring endothelial cells split the newly formed vessels and branching takes place. In neurohypophysis we can observe all stages of non-sprouting angiogenesis: proliferation endothelial cells on the inside mother vessel, splitting newly formed blood vessels by transcapillary pillars directed into the vessel lumen, maturation of endothelium and network formation., Conclusion: The mechanical injuries directly induced angiogenesis not only in cerebral cortex, but also in neurohypophysis. Our studies show that mechanism of angiogenesis is not the same as observed previously in neurohypophysis after focal cerebral ischemia (Neuroendocrinology Letters 2001; 22:87 92). This study indicates that mechanism of angiogenesis can depend on kind of induction.

In the present study we used a cytochemical method for electron microscopy for nitric oxide synthase (NOS) detection in rat cerebral cortex. The animals were subjected to total brain ischemia and mechanical trauma. Tissue was fixed in 3% paraformaldehyde and 0.5% glutaraldehyde which enabled excellent preservation of cellular ultrastructure and resulted in an increase in method reproducibility. The results show the distribution of the particles reflecting the sites of NOS activity in the capillaries and other, more distant locations. NOS activity was found in thrombocytes, endothelium and pericytes. Moreover, the morphologically differentiated perivascular phagocytes demonstrated NOS reaction product in their cytoplasm. These phagocytes containing polymorphic phagolysosomes, surrounded the fragments of damaged neurons. We propose that these cells are descendants of blood-borne monocytes and transformed pericytes. In the areas distant to the sites of injury we noticed cells showing ultrastructural features of activated microglia. These cells were in a close contact with neural perikarya and contained iNOS-specific reaction product in the cytoplasm. In conclusion, our studies revealed differentiated forms of brain phagocytes, the occurrence of which depended on the type of cerebral injury. These cells demonstrated NOS reaction product suggesting their role in cerebral NO production during ischemia and other forms of brain injury.