Generation and Evaluation of Novel Stromal Cell-Containing Tissue Engineered Artificial Stromas for the Surgical Repair of Abdominal Defects.

Repair of abdominal wall defects is one of the major clinical challenges in abdominal surgery. Most biomaterials are associated to infection and severe complications, making necessary safer and more biocompatible approaches. In the present work, the adequate mechanical properties of synthetic polymer meshes with tissue-engineered matrices containing stromal mesenchymal cells is combined to generate a novel cell-containing tissue-like artificial stroma (SCTLAS) for use in abdominal wall repair. SCTLAS consisting on fibrin-agarose hydrogels seeded with stromal cells and reinforced with commercial surgical meshes (SM) are evaluated in vitro and in vivo in animal models of abdominal wall defect. Inflammatory cells, collagen, and extracellular matrix (ECM) components are analyzed and compared with grafted SM. Use of SCTLAS results in less inflammation and less fibrosis than SM, with most ECM components being very similar to control abdominal wall tissues. Cell migration and ECM remodeling within SCTLAS is comparable to control tissues. The use of SCTLAS could contribute to reduce the side-effects associated to currently available SM and regenerated tissues are more similar to control abdominal wall tissues. Bioengineered SCTLAS could contribute to a safer treatment of abdominal wall defects with higher biocompatibility than currently available SM.

Ex vivo construction of a novel model of bioengineered bladder mucosa: A preliminary study.

OBJECTIVE: To generate and to evaluate ex vivo a novel model of bioengineered human bladder mucosa based on fibrin-agarose biomaterials. METHODS: We first established primary cultures of stromal and epithelial cells from small biopsies of the human bladder using enzymatic digestion and selective cell culture media. Then, a bioengineered substitute of the bladder lamina propria was generated using cultured stromal cells and fibrin-agarose scaffolds, and the epithelial cells were then subcultured on top to generate a complete bladder mucosa substitute. Evaluation of this substitute was carried out by cell viability and histological analyses, immunohistochemistry for key epithelial markers and transmission electron microscopy. RESULTS: The results show a well-configured stroma substitute with a single-layer epithelium on top. This substitute was equivalent to the control bladder mucosa. After 7 days of ex vivo development, the epithelial layer expressed pancytokeratin, and cytokeratins CK7, CK8 and CK13, as well as filaggrin and ZO-2, with negative expression of CK4 and uroplakin III. A reduction of the expression of CK8, filaggrin and ZO-2 was found at day 14 of development. An immature basement membrane was detected at the transition between the epithelium and the lamina propria, with the presence of epithelial hemidesmosomes, interdigitations and immature desmosomes. CONCLUSIONS: The present results suggest that this model of bioengineered human bladder mucosa shared structural and functional similarities with the native bladder mucosa, although the epithelial cells were not fully differentiated ex vivo. We hypothesize that this bladder mucosa substitute could have potential clinical usefulness after in vivo implantation.