Promotion of tracheal cartilage growth by intra-tracheal injection of basic fibroblast growth factor (b-FGF)

PurposeBasic fibroblast growth factor (b-FGF) is a very effective growth factor that induces the proliferation of chondrocytes. This study aimed to investigate whether intra-tracheally-injected b-FGF solution promotes the growth of tracheal cartilage.MethodsGroup 1: 500 μl of distilled water was injected at the posterior wall of the cervical trachea of New Zealand white rabbits by using a tracheoscope (n = 5). Group 2: 100 μg/500 μl of b-FGF solution was injected at the posterior wall of the cervical trachea (n = 5). Group 3: Biodegradable gelatin hydrogel microspheres incorporating 100 μg/500 μl of b-FGF solution were injected at the posterior wall of the cervical trachea (n = 5). All animals were sacrificed 4 weeks later, and the outer diameter and luminal area of the cervical trachea at the site of b-FGF injection were measured.ResultsThe cervical tracheas in the two b-FGF injection groups were spindle-shaped and had a maximum diameter at the injection site. The median outer diameter of the cervical trachea in Groups 1, 2, and 3 was 7.3, 8.0, and 8.0 mm, respectively, showing a significant difference among Groups 1, 2, and 3 (P = 0.04). The median luminal area in Groups 1, 2, and 3 was 27.4, 29.4, and 32.1 mm2, respectively. The ad hoc test showed a marginally significant difference only between groups 1 and 3 (p = 0.056).ConclusionIntra-tracheal injection of slowly released b-FGF enlarged the tracheal lumen.