Intra-thoracic fibrous tissue induction by polylactic acid and epsilon-caprolactone copolymer cubes, with or without slow release of basic fibroblast growth factor.

Objective: We investigated whether implantation of polylactic acid and epsilon-caprolactone copolymer (PLAC) cubes with or without basic fibroblast growth factor (b-FGF) released slowly from gelatin microspheres was able to induce fibrous tissue in the dead space remaining after pneumonectomy in the thoracic cavity.

Methods: Left pneumonectomy was performed in Japanese white rabbits. In the control group (n=6), the left thoracic cavity was closed without any treatment. In the FGF group (n=6), gelatin microspheres that released 100 microg of b-FGF were implanted into the left thoracic cavity. In the PLAC group (n=6), PLAC cubes were implanted into the left thoracic cavity. In the PLAC/FGF group (n=6), both PLAC cubes and gelatin microspheres releasing 100 microg of b-FGF were implanted into the left thoracic cavity.

Results: In the control and FGF groups, herniation of the heart, mediastinal shift, and overinflation of the right lung were observed. No granular tissue formation was observed. In the PLAC and PLAC/FGF groups, a dense area of newly formed soft tissue was observed, and only a mild mediastinal shift was observed during the 3-month follow-up period. Pathological examination revealed induction of fibrous and granular tissue in the left thoracic cavity. The foreign-body reaction induced by PLAC was very mild.

Conclusions: Implantation of PLAC cubes with or without gelatin microspheres releasing 100 microg of b-FGF is able to induce fibrous tissue in the post-pneumonectomy dead space.