Two kinds of gel materials were prepared from silk fibroin with polyepoxy compound at subfreezing temperature and higher temperature. In order to evaluate the feasibility of their application in biomaterials, we tested the cytotoxicity of silk fibroin gels by detecting the effect of the extracted liquid on the cell relative proliferation rate of L-929 mouse fibroblasts. The results indicated that both of the gel materials displayed high relative proliferation rate and grade 1 cytotoxicity, being in the allowed range of medical application. The cytotoxicity tests on polyepoxy compound and glutaraldehyde were conducted too, and the cytotoxicity of polyepoxy compound was obviously lower than that of glutaraldehyde. Polyepoxy compound can be used as a more safe cross-link reagent for silk fibroin modification.
Animals ; Biocompatible Materials ; chemistry ; Bombyx ; chemistry ; Cross-Linking Reagents ; chemistry ; Fibroblasts ; drug effects ; Fibroins ; chemistry ; Gels ; chemical synthesis ; toxicity ; Mice ; Polyethylene Glycols ; chemistry ; Temperature

In this research project, rats were made into animal models of acute focal cerebral ischemia and reperfusion (IR) by occlusion of their middle cerebral artery (MCAO). We observed the effect of endogenous endothelial progenitor cells (EPCs) and serum cytokines on cerebral ischemia rats treated by electro-acupuncture(EA). The results showed: MCAO model had high stability after EA treatment which was delivered via the acupuncture needles inserted into "quchi" and "zusanli" points, the nervous functions of cerebral IR rats recovered faster than those of rats not treated; EPCs in rats' blood increased after acute focal cerebral ischemia and reperfusion; and the growth rate was obvious in IR group. This phenomenon might be related to the inflammation elicited by injury of ischemia and self-repair. Besides, EA treatment could decrease induced nitric oxide synthase (iNOS) activity, alleviate injury after cerebral ischemia, and regulate the quantity of EPCs in blood. The quantity of EPCs in blood increased in IR-24hr. In IR-48 hr, the rise of EPCs quantity was significant (P < 0.01). The level of vascular endothelium growth factor (VEGF) in serum of rats after cerebral ischemia was escalated, which indicated to a certain extent that cerebral ischemia could stimulate stress reaction. EA treatment could raise VEGF level, which suggested that high expression of VEGF could accelerate mobilization, chemotaxis and homing of EPCs. At the same time, the levels of matrix metalloproteinase-9 (MMP-9) and basic fibroblast growth factor (bFGF) also changed. In conclusion, EA treatment could promote neovascularization after cerebral ischemia by mobilizing EPCs, decreasing iNOS activity and increasing VEGF level. This may be one of the ways by which EA could treat cerebral ischemia.
Animals ; Brain Ischemia ; blood ; complications ; pathology ; Cytokines ; blood ; Electroacupuncture ; Endothelial Cells ; cytology ; Infarction, Middle Cerebral Artery ; blood ; pathology ; Male ; Rats ; Rats, Sprague-Dawley ; Reperfusion Injury ; blood ; pathology ; Stem Cells ; cytology