Construction of Tissue-Engineered Bladders Using an Artificial Acellular Nanocomposite Scaffold Loaded with Stromal Vascular Fraction Secretome.

Tissue engineering approaches offer promising alternative strategies for reconstructing bladder tissue; however, the low retention of transplanted cells and the possible risk of rejection limit their therapeu-tic efficacy. Clinical applicability is further limited by the lack of suitable scaffold materials to support the needs of various cell types. In the present study, we developed an artificial nanoscaffold system con-sisting of stromal vascular fraction (SVF) secretome (Sec) loaded onto zeolitic imidazolate framework-8 (ZIF-8) nanoparticles, which were then incorporated into bladder acellular matrix. This artificial acellu-lar nanocomposite scaffold (ANS) can achieve gradient degradation and slowly release SVF-Sec to promote tissue regeneration. Furthermore, even after long-term cryopreservation, this completely acellular bladder nanoscaffold material still maintains its efficacy. In a rat bladder replacement model, ANS transplantation demonstrated potent proangiogenic ability and induced M2 macrophage polarization to promote tissue regeneration and restore bladder function. Our study demonstrates the safety and efficacy of the ANS, which can play a stem cell-like role while avoiding the disadvantages of cell therapy. Furthermore, the ANS can replace the bladder regeneration model based on cell-binding scaffold materials and has the potential for clinical application.Statement of significance This study aimed to develop a gradient-degradable artificial acellular nanocomposite scaffold (ANS) loaded with stromal vascular fraction (SVF) secretome for rehabilitating bladders. Using various in vitro methods as well as rat-and zebrafish-based in vivo models, the developed ANS was assessed for effi-cacy and safety. Results indicated that the ANS achieved gradient degradation and slowly released the SVF secretome to promote tissue regeneration, even after long-term cryopreservation. Furthermore, ANS transplantation demonstrated a potent pro-angiogenic ability and induced M2 macrophage polarization to promote tissue regeneration and restore bladder function in a bladder replacement model. Our study demonstrates that ANS may replace bladder regeneration models based on cell-binding scaffold materials and have potential clinical application & COPY; 2023 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.