Devascularization due to large lymph node dissection is one of the causative factors of bronchial stump fistula (BF). In this work we have developed and analyzed the utility of a tissue allograft composed of alginate polymer (AP), autologous fibrin (AF), tissue-engineered fibroblasts (TEF), vascular endotelial growth factor (VEGF) and encapsulated fibroblast growth factor (FGF) to prevent BF and promote revascularization of the bronchial stump in a pig pneumonectomy model. To validate the system a left pneumonectomy was performed in 15 pigs, leaving a long and exhaustively devascularized bronchial stump. The animals were allocated in groups of five to receive no bronchial stump coverage (group A), coverage with AP + AF only (group B) or coverage with AP + AF + TEF + VEGF + FGF (group C). After being euthanized on postoperative days 3,7, 14 , 21 and 30, bronchial stumps for each group were tested for BF occurrence and subsequently sectioned for histology and stained with hematoxylin-eosin, CD-31 and α-smooth muscle actin antibodies to evaluate blood vessels formation and maturation, capillary density and TEF proliferation by means of a semiquantitative method.
From the analysis done it can be concluded that: No BF could be detected for any group, probably due to a high spontaneous healing capacity of pig tissues. In group A, fibroblastic proliferation and revascularization were scarce; group B showed some immature neovessels besides a moderate TEF proliferation while in group C, in addition to an intense TEF proliferation, a large number of vascular yolks could be detected on postoperative day 7, continuing to complete vascular structures on postoperative day 14 within a highly dense capillary network. Therefore, the avascular scaffold highly promotes revascularization of the denudated bronchial stump. Further studies are being done to clarify the clinical application of these findings.
