| Artificial joints displacement has become one of the major strategies that are used intreatment of diseases in joints. Joints displacement has been given the reputation of a famousmilestone in the development history of bone science. Materials used for the artificial jointsneed to be of excellent biocompatibility, of no potential to producing side effects, of longduration, of sustained wearability, and of no subject to loosing. Polyimide material possessesthe characteristics of physical and chemical stability, flexibility, surface adherence,lubrication, biomechanical support and is an ideal transplanting material. So far, there is noreport on the PI as a transplanting material in domestic and limited research in abroad. Thepresent study will investigate the biocompatibility of the polyimide material enhanced bycarbon fiber designed and produced by Applied Chemistry institute of Changchun and textileindustry design institute of Jilin Province through in vitro cytotoxicity evaluation, in vivotransplanting experiment, genetic toxicity assessment to provide experimental evidence forthe application of polyimide in clinical practice.Objectives: To explore the biocompatibility of the polyimide carbon fiber reinforcedmaterials and evaluate the potential of utilizing PI in artificial displacement in clinicalpractice.Materials and Methods1.108Wistar rats were divided into six groups, control group, positive control group,pseudo-operation group, PI low dosage group, PI medium dosage group and PI high dosagegroup, each group having18rats. PI was transplanted into the back of PI group. Inpseudo-operation group, rats were cut in the back, but no PI was transplanted. PVC was putinto the back of positive group rats. On the day of one week, four weeks and12weeks afterPI was transplanted into the rats,6rats were randomly selected from each group and wereanesthetized and killed, blood and urine were collected for the test; skin around the PI material, kidney, liver, pancreas and spleen were removed and pathological test wasconducted.2. Fur in the back of6white rabbits were removed4or24h prior to experiment, thesurface area was about10cm×15cm square.0.5ml of extract from PI material was directlyput on the back skin which was covered by bandage for at least4h. Ink was used to mark thearea with PI. Under natural light or full spectrum light, the skin in contact with PI extract wasobserved and skin erythema and swelling were recorded.3.PI material was washed with ethanol by ultrasonic cleaning for20min，then rinsed bydistilled water several times, dried in dryer and sterilized. Based on the regulations ofGB/T16886.12, PI material and extract liquid should be at the ratio of6cm2·ml-1. The extractliquid was RPMI-1640supplemented with10%FBS. The extract process was performed at39℃for72h in the constant temperature shaker. Vero cells were used for the detection ofcytotoxicity of PI. MTT assay was conducted to determine the cell survival rate. After verocells were co-cultured with PI for24h，48h and72h, the cell survival rate was determined.4.50kunming mice were randomly divided into5groups, PI extract low dosage group(5ml/kg), medium dosage group (10ml/kg), high dosage group (20ml/kg), positive controlgroup and control group. Cyclophosphamide was administered to positive group rats at thedosage of80mg/kg30h and6h prior to the end of the experiment respectivelyintraperitoneally. PI extract was administered to mice through gastric injection forconsecutive30days. Saline was administered to control group mice through gastric injectionfor consecutive30days. Micronuclear and chromosome aberration was detected in thesemice.Results1. Blood test results showed that the number of lymphocytes and monocytes of rats frompositive group were significantly higher than those from control, pseudo-operation and PIgroups on one week, four weeks and12weeks after transplanting (P<0.05). Bloodhemoglobin content and mean blood platelet of rats from positive group were significantlylower than those from other groups (P<0.05); There was no significant difference of specificred blood cell volume and blood platelet range (P﹥0.05). The levels of aspartate aminotransferase and Alanine aminotransferase of rats frompositive group were significantly higher than those from control, pseudo-operation group, PIlow dosage group, medium dosage group an d high dosage group (P<0.05). Total proteinlevels of rats from positive group were the highest among the rats of all groups (P<0.05).Globulin levels and ratio of albumin to globulin of rats from positive group weresignificantly higher than those from others groups (P<0.05). Urea nitrogen levels of ratsfrom positive group were significantly higher than those from other groups (P<0.05).On one week, four weeks and12weeks after transplanting, the number of white bloodcells and pathological tube in urine of rats from positive group were significantly higherthan those from other groups.Pathological detection showed that there was no pathological changes in the skin, liver,kidney, pancreas and spleen of rats from control, pseudo-operation, PI low dosage group,medium dosage group and high dosage group on one week, four weeks and12weeks aftertransplanting. For the positive control group, on the first week, inflammatory cell infiltrationwas seen in transplanted skin; on four week, inflammatory granulation was seen in thetransplanted skin; on12week, fiber wrap was in the transplanted skin, brown particles wereseen in the liver and liver cells manifested necrotic degeneration; brown particles wereoccasionally seen in the cells of kidney, spleen and pancreas.2.Mild erythema was seen on the skin of rabbits in contact with PVC extract while noerythema and swelling was seen on the skin of rabbits in contact with PI material.3. There was no significant difference in the survival rate of vero cells between cellsco-cultured with PI extract and control cells. However, the survival rate of vero cells in PVCextract was significantly decreased.4. Micronuclear rate of mice from positive group was significantly higher than that fromPI groups. There was no significant difference of micronuclear rate between control groupmice and PI groups.Chromosome aberration was seen in mice from positive group while no chromosomeaberration was found in mice from control and PI extract groups. ConclusionPI was of excellent biocompatibility based on the results from in vivo transplantingexperiment evaluation, skin sensitization test, cytotoxicity test and genetic toxicityassessment. |
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