Experimental Study On Biocompatibility Of Stone Needle

OBJECTIVE:To evaluate the biological compatibility of stone needle via animal implantation experiments, cytotoxicity experiments in vitro, and animal skin irritation experiments.METHODS:According to GB/T1688and ISO/10993standards, stone needle from Sibin area is used to conduct animal implantation experiments, cytotoxicity experiments in vitro, and animal skin irritation experiments.1. Animal implantation experiments:①Experimental materials:stone needles from Sibin area and T-shaped silicone stents。②Experimental groups:Sterile stone needle and silica module are embedded between the superficial fascia and muscle in the rat’s back respectively. Rats implanted with stone needle is the experimental group, Rats implanted with T-shaped silicone stent the control group and Rats cut open and then sutured on waist the blank group. Kill the Rats under narcotism on the7th,30th and90th days after surgery respectively, and then take out the embedded modules together with a few of surrounding tissues. Observe the inflammatory cell responses and changes of surrounding tissues of the implanted materials through microscope.2. cytotoxicity experiments in vitro:Fibroblast (L929) of mice were fostered with1640culture medium adding leach liquors of different concentrations from stone needle and silica gel respectively to assess cytotoxicity of stone needle through MTT staining method on the1th,3th, and7th days.3. Animal skin irritation experiments:remain the pasters on the surface of skin for at least4hours. Stone needle grinded into powders is the experimental group, sterile desensitization medical gauze the control group. Record and grade the condition of contact area respectively in1h,24h,48h and72h after removing the paster till the14th day.RESULTS1. Animal implantation experiments:7days after implantation, increased capillary dilatation, congestion, neutrophils, and lymphocytes infiltrating surrounding capillaries are found in the surrounding tissues of two groups and cyst wall formation is not found.30days after implantation, a moderate quantity of new capillaries, a less than moderate quantity of inflammatory cells (including lymphs and neutrophils) and a small quantity of loose cyst wall structures are found in surrounding tissues.90days after implantation, dense, thin-walled and transparent cyst wall structures are found in the surrounding tissues. There is no significant difference between the two kinds of materials (P>0.05).2. cytotoxicity experiments in vitro:Leach liquors of different concentrations from stone needle contribute to the proliferation of L929cells (P<0.01). There are no significant differences among various concentrations on the1th,3th and7th days (P>0.05), and the cytotoxicity of stone needle is rated grade0-1.3. Animal skin irritation experiments:1h,24h,48h and72h after being contacted with two groups of material for5hours, no chromatosis, no erythema, no eschar and edema are found in the surface of skin through the naked eyes and microscope (5times). After being observed for14days continuously, primary irritating index (PII) of the skin is0, and there is no significant difference between two groups (P>0.05).CONCLUSION:Stone needle has good biological compatibility, which offers definite experimental basis to clinical application.