| Objecctives Stress urinary incontinence (SUI) is a common disease among adult females, which seriously affects both physical and mental well-being of women. To explore a new method for curing SUI, we intend to develop an animal model to stimulate SUI, on which we try to treat SUI by urethral injection of stem cells compounded with calcium alginate gel.Materials and MethodsPart I:An animal model stimulating SUI and evaluation. Eighteen 6-weeks old female SD rats (weighing from 190-220g) were randomly distributed into 3 groups:experimental group, sham operation group and negative control group. Rats in experimental group were underwent bilateral transaction of pudendal nerves and nerves to iliococcygeous/pubococcygeous muscles, while rats in the sham operation group were not performed nerve transaction. The negative control group did not undergo any operation. Leak point pressure (LPP) was evaluated by measuring the inner-urethra pressure when leakage of urine occured on each rat 2 weeks after the operation. Group average LPPs were calculated for static analysis. After the measurement of LPP, transverse sections of mid-urethra were taken for histological examination.Part II:Trial of treating SUI by urethral injection of stem cells/myogenic cells compounded with calcium alginate gel. 108 6-week old female rats were randomly distributed into 6 groups:control group, gel group, BMSCs group, myogenic cells(MCs) group, BMSCs/gel group, MCs/gel group. All 6 groups of rats underwent bilateral transaction of pudendal nerves and nerves to iliococcygeous/pubococcygeous muscles.2 weeks later different material was injected into urethral surrounding tissue according to different groups.1 week,4 weeks and 8 weeks after injection, certain number of rats in each group were taken out for evaluation of LPP. After the measurement of LPP, transverse sections of mid-urethra were taken for histological examination. ResultsPart I:One rat in the sham op group died 1 week after the operation. The LPP of experimental group decreased significantly by approximately 33% compared with the sham operation group and the negative control group (P<0.05). However, there was no statistically significant difference between the LPPs of control group and sham op group (P>0.05). The histological examination showed urethral striated muscle atrophy in mice of the experimental group.Part II:14 rats were killed before LPP measurement. Static analysis for group average LPPs showed significant difference in control group vs gel group, control group vs BMSCs/gel group and control group vs MCs/gel group. On the contrast, no significant difference were found among control group, BMSCs group and MCs group. Neither was there any difference of significance among gel group, BMSCs/gel group and MCs/gel group. Immunohistochemistry showed the existence of gel in MCs/gel group of 4/8-week and BMSCs/gel group of 4-week. Cells with the expression of desmin were found inside the gel matrix. However, no evidence of either gel or ectogenous cells were found in other exemplars.ConclusionsBilateral transaction of pudendal nerves and nerves to iliococcygeous/ pubococcygeous muscles results in SUI in rats stably. This model could be used in the study of the mechanism of SUI and in the trial of new treatments for SUI.Using urethral injection of gel only, BMSCs/gel or MCs/gel could improve the LPP of SUI rats. Whether cells existed didn't make any significant difference on LPP.Myogenic cells may maintain stable after injection. BMSCs may differentiate into muscle cells when injected into muscle tissue. Though exact evidence needs further research. |
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