Background: Injury of the central nervous system (CNS) of mammals may cause irreparable damage due to the limited regeneration capacity of the tissue. In order for the CNS tissue to regenerate, to supply a scaffold for the newly produced cells to adhere is necessary. Application of biodegradable polymers such as collagen, gelatin, fibrin and alginates has been investigated for organ damage other than the CNS. In this context, we recently produced a novel biomaterial from polydimethylsiloxane (PDMS) and tetraethoxysilane (TEOS). We added the most potent angiogenic factor vascular endothelial growth factor (VEGF) and observed the difference in brain regenerative process in the PDMS-TEOS scaffold. Methods: Male Wistar rats of 12 weeks old were anesthetized and placed in a stereotaxic apparatus. A piece of bone over the right frontal cortex was excised, and 2 x 5 mm defect in the brain was made by cutting and aspiration. The defect was positioned from 1.0 mm anterior to 4.0 mm posterior of the bregma and 2.0 to 4.0 mm lateral to the midline. The depth of the lesion was 2.0 mm from the brain surface. The block of PDMS-TEOS scaffold, with or without VEGF, was placed into the lesion immediately after making the defect. The animals were sacrificed at 30 days after PDMS-TEOS scaffold implantation. For histological analysis of the newly formed tissue, the sections were stained with HE. In order to identify cell types in the newly formed tissue, we performed immunohistochemical analysis for glial fibrillary acidic protein (GFAP), an astrocyte marker, and N-acetylglucosamine oligomer (NAGO), an endothelial cells marker. In order to determine whether the cells in PDMS-TEOS scaffold were under mitosis, we carried out double fluorescent study for cell phenotype markers and Ki67. Result: The PDMS-TEOS scaffold remained at the implanted site for 30 days and kept the integrity of brain shape (Fig. A and B). HE staining showed that a small number of cells infiltrated into the PDMS-TEOS scaffold even without VEGF at 30 days after the implantation, but that addition of VEGF significantly increased the number of infiltrated cells NAGO staining showed only a few positive cells in the PDMS-TEOS scaffold without VEGF, but significant increase of endothelial cells with VEGF was confirmed. Immunohistochemical study for GFAP demonstrated that only a few astrocytes were found in the PDMS-TEOS scaffold without VEGF, which was again significantly increased with VEGF. Double staining with proliferation maker Ki67 demonstrated that VEGF significantly increased newly formed astrocytes and endotheial cells, indicating that addition of VEGF accelerated tissue restoration and angiogenesis. Conclusions: The present study showed that a new porous PDMS-TEOS is a good candidate biomaterial for brain tissue restoration. Endothelial as well as glial cells successfully infiltrated into this biomaterial. Addition of VEGF further promoted new tissue formation.
|Journal of Cerebral Blood Flow and Metabolism
|Published - Nov 13 2007
All Science Journal Classification (ASJC) codes
- Clinical Neurology
- Cardiology and Cardiovascular Medicine