Early effects of adipose-derived stem cell sheets against detrusor underactivity in a rat cryo-injury model

Aims: This study investigated the effects of adipose-derived stem cell sheets on a rat model of detrusor underactivity. Main methods: Adipose-derived stem cell sheets were prepared from the subcutaneous adipose tissue of male Lewis rats. Female Lewis rats were assigned into four groups: control, sham operation, cryo-injury, and cryoinjury+sheet (n = 8 per group). Rats in the cryo-injury+sheet group were implanted with ASC sheets 3 days after cryo-injury induction and underwent cystometry 7 days later. Subsequently, reverse transcription-polymerase chain reaction (RT-PCR) and histopathological examinations were performed. Cell sheets expressing the green fluorescent protein were prepared and transplanted to confirm the viability and differentiation of the sheets. Fluorescence was confirmed using a fluorescence stereomicroscope on days 3, 7, 14, 21, and 28 after sheet implantation, and tissue immunostaining was performed. Key findings: Cystometry showed that sheet implantation improved the maximum intravesical pressure (P = 0.009) and the residual urine volume (P = 0.011). Furthermore, RT-PCR indicated that the mRNA levels of the angiogenic factors vascular endothelial growth factor and hepatocyte growth factor were significantly higher in the cryo-injury+sheet group than in the cryo-injury group (P = 0.045, P = 0.037, respectively). Histologically, sheet implantation resulted in an improvement in inflammation and increased the number of blood vessels. Green fluorescent protein-positive cells fused with von Willebrand factor-positive cells and differentiated into blood vessels 7 days after sheet implantation. Significance: Adipose-derived stem cell sheets transplanted into the bladder of cryo-injured rats differentiated into blood vessels and restored bladder contractile function 7 days after transplantation.