Objective      To observe the biocompatibility and mechanical properties of composite polypropylene mesh (PM) in rats

which was obtained by inoculating urinary bladder matrix (UBM) with bone mesenchymal stem cells (BMSCs)

and to discuss its application as prosthetic material in repair and reconstruction of the pelvic floor tissue.       Methods      Sprague-Dawley rats were divided into BMSCs-UBM-PM group

UBM-PM group

PM group

and sham-operation group. All the materials were implanted on the  abdominal rectus muscle of rats separately. The composite meshes and surrounding tissues were harvested in the 1st

2nd

4th and 6th week after implantation. The histopathological changes were observed by HE staining. The survival and differentiation of BMSCs in BMSCs-UBM-PM group were observed by immunofluorescence staining. Six weeks after implantation

the materials were subjected to a mechanical property test.       Results      HE staining showed that infiltration of inflammatory cells was more sparse and the new blood vessels were more abundant in BMSCs-UBM-PM group. Immunofluorescence staining showed that BMSCs could survive for at least 6 weeks in vivo and could partly differentiate into smooth muscle cells. In the 6th week

the composite mesh of BMSCs-UBM-PM group showed the maximum load of 0.31±0.08 kN

maximum tension displacement ratio of 0.62±0.19 mm/mm

and Young’s modulus of 43.36±11.83 MPa

which were significantly higher than those of other groups (P0.05).       Conclusion      BMSCs-UBM-PM exhibits excellent biocompatibility after implantation and causes relatively weaker inflammatory response. BMSCs can be induced to differentiate to smooth muscle cells

thus providing higher tensile strength to the composite mesh that can be used as candidate material for repair and reconstruction of pelvic tissue.