Objective To identify the effect of decreasing the rejection using the biological semipermeable membrane combined with the privileged site xenotransplantation. Methods The rat ICCs encapsulated by biological semipermeable membrane were xenotransplanted into dog's brain. The pathological changes of implants and surrounding cerebral tissues were observed under light and electric microscopy. The ?-cells of implants were identified by immunohistochemistry. Results After 2 months of transplantation, The ?-cells were observed and the lymphocytes were dispersed in the grafts.The brain tissues near the grafts showed slight edema and glial hyperplasia. Conclusion The method using the biological semipermeable membrane in combination with the privileged site xenotransplantation have a beneficial effect on the inhibition of the rejection of heterogeneous ICCs implant.

Objective To study the mechanism of arachnoidal fibrosis after subarachnoid hemor- rhage. Methods Rats were divided into control group, experiment group and treatment group. Radioim- munoassay (RIA) was employed to detect the levels of hyaluronic acid, laminin,type Ⅲ precollagen and type Ⅳ collagen in the arachnoid membrane. In the meantime, arachnoid cell's morphology and collagen distribution in the subarachnoid space were investigated by electron microscope. Results Results of RIA detection showed increase of Type Ⅲ precollagen level (peak at the second week), obvious higher levels of LN and HA but insignificant change of type IV collagen after subarachnoid hemorrhage. However, dexam- ethasone treatment decreased type Ⅲ precollagen level. Electron microscope found that arachnoid cells pres- ented accentruated bioactivity after subarachnoid hemorrhage, with significant increase of arachnoidal colla- gen fibers from one week after suharachnoid hemorrhage, continuing for 3 weeks. Dexamethasone treatment resulted in low density of mitochondria and sparsed arachnoidal collagen fibers. Conclusions Extracellu- lar matrix (ECM) increases in arachnoid membrane after subarachnoid hemorrhage and participates in a- rachnoid fibrosis. Dexamethasoue can relieve arachnoidal fibrosis after subarachnoid hemorrhage, as pro- rides fresh way for prevention and treatment of post hemorrhagic hydrocephalus.