Bladder muscle regeneration enhanced by sustainably delivering heparin from the bilayered scaffolds carrying stem cells in a rat bladder partial cystectomy model.

In bladder tissue engineering, the regeneration of muscles is equally important to epithelium. However, there is a lack of effective strategy for promoting bladder muscles regeneration. In this study, we aim to promote bladder muscle regeneration by sustainably delivering heparin from the bilayered scaffold carrying stem cells. The bilayered scaffold (Hep-PB/PCL) comprises a electrospun layer (Hep-PB electrospun membrane) and a three-dimensional (3D) printing layer (polycaprolactone (PCL) scaffold), which were fabricated via coaxial-electrospinning and 3D printing, respectively. Heparin was encapsulated into the core of the Hep-PB fibers with core-shell structure to sustain its release. The morphology of the bilayer scaffold and the microstructure of the electrospun fibers were characterized. The release behaviors of heparin from various electrospun membranes were evaluated. The role of Hep-PB in promoting myogenic differentiation of the adipose-derived stem cells (ADSCs) through sustainably releasing heparin was also evaluated. After 7 days' culture, the Hep-PB/PCL scaffolds carrying ADSCs (defined as ASHP) were used for bladder reconstruction in a rat model of cystotomy. The result shows that the PCL printed scaffold has ordered macropores (~370 μm), which differs from the compact microstructure of electrospun films. The Hep-PB membrane exhibits a sustained release behavior for heparin. This membrane also shows better growth and proliferation of ADSCs than the other groups. The result of polymerase chain reaction (PCR) shows that the expression of smooth muscle cell markers in ADSCs is enhanced by the Hep-PB scaffold. The results of retrograde urethrography and histological staining indicate that the bladder volume in ASHP group recovers better, and the regenerated bladder muscle bundles arrange more orderly compared with direct suture group and bladder decellularized matrix group. Therefore, findings from this study show that the bladder muscle regeneration could be enhanced by the bilayered scaffolds delivering heparin and carrying stem cells, which may provide a new strategy for bladder tissue engineering.