Experimental Study On The Effect Of Magnetic Silicon Rubber Retainer To EGF And BFGF Expression Of Rat Local Skin Tissue In Vivo

Objective Prof. Zhang designed a new craniofacial prostheses retainer—Magnetic Silicon Rubber Retainer. On the basis of preliminary experiment study on the cytotoxicity and histological biocompatibility, we got a further step to study on the effect of magnetic silicon rubber retainer to EGF and bFGF expression of rat local skin tissue In Vivo. As offer the further experiment basis for clinical practice of this new material. Methods After making the magnetic material into the size of 2mm×2mm×1mm volume and enwrapped in silicon rubber, we implanted experiment materials (including investigating sample and contrast sample) under both sides hypodermis of the back vertebra (distance to central line was 2.0cm) of established SD rat model according to divided groups. Each rat was planted into 4, magnetized and fixed by another magnetic silicon rubber with opposite magnetic pole on corresponding skin surface of implanted samples 2 weeks later, comparing with silicon rubber contrast, normal contrast and normal wound contrast. We investigated the histological reaction of local skin and hypodermis by naked eye and light microscope after 1 week, 4 week, 12 week and 26 week separately. Simultaneously we gather skin specimen, then analyzing EGF and bFGF expression and its significance of the sample skin by using immunohistochemistry pigmentation counting and ELISA method. Result 1.EGF and bFGF immunohistochemistry pigmentation test: ⑴EGF: We observed that there was slight to moderate EGF expression in the skin of normal skin contrast group (N), also low-grade expression in folliculi sheath cell, sebaceous gland cell and sweat gland cell. In normal wound contrast group (NW), silicon rubber contrast group (S) and magnetic silicon rubber retainer group (M), the expression of EGF at local skin was lower than N group during forepart injury. Then the EGF expression began up-regulating after 1 week. There was no observed difference among NW group, S group and M group during healing procedure. ⑵bFGF: We observed that there was slight to moderate bFGF expression in epidermal cell, fibroblast cell and endothelium cell of the skin in normal skin contrast group (N). The changes of bFGF expression in NW group, S group and M group were similar with that of EGF. 2. EGF and bFGF ELISA quantitative analysis: The EGF and bFGF expression of normal skin contrast group (N) was smooth and undiversity. In normal wound contrast group (NW), silicon rubber contrast group (S) and magnetic silicon rubber retainer group (M), the expression of EGF and bFGF at local skin was lower than N group during forepart surgical procedure (P<0.01). Then the EGF expression began up-regulating after 1 week (P<0.05), and re-normal assumably in 12 weeks which had no difference with N group (P>0.05). There was no observed difference among NW group, S group and M group (P>0.05) during healing procedure. The result was consistent of immunohistochemistry pigmentation counting and ELISA quantitative analysis methods. Conclusion 1.The medical biomaterial needs to carry on many biological compatibility experiment before applying to the human body, as the internationalized standard file (109930 ISO) and the national standard organization of our country (GB/T 16886 series) have regulated about indetail. Our team leading by Prof. Zhang has been setting up experimental animal model to study the biological compatibility of the new material— magnetic silicon rubber retainer according to the standard series request in this subject. 2. The result of Implantation test showed the magnetic silicon rubber didn't cause abnormal behavior of rat. The reactions of local skin were slight. The observing of local skin slice under microscope indicates that magnetic silicon rubber has well biological tissue compatibility. 3. On the basis of preliminary experiment study on the cytotoxicity and histological biocompatibility, we got a further step to contrast study on the effect of magnetic silicon rubber retainer to cytokine (EGF and bFGF) expression of rat local skin tissue when impla...