Slow release of basic fibroblast growth factor (b-FGF) enhances mechanical properties of rat trachea

Tracheal cartilage growth promotion by intra-tracheal administration of basic FGF

PURPOSE

This study aimed to investigate whether intra-tracheal administration of basic fibroblast growth factor (b-FGF) promotes the growth of tracheal cartilage.

METHODS

Trachea of 4-week old mice were intubated and 2.5 μg b-FGF administered (Group 4) for periods from 1 to 5 days. Cervical tracheal outer diameter and tracheal ring length were compared in Group 1 (no intervention), Group 2 (tracheal intubation), Group 3 (intra-tracheal administration of distilled water) and Group 4, at 8 weeks of age. Outer diameter and tracheal ring length in Group 4 were also compared with that in Group 1 at 12 and 16 weeks of age.

RESULTS

At 8 weeks of age, tracheal ring length with b-FGF administration for more than 4 days in Group 4 was significantly increased over that following 1-day administration. At 8 weeks of age, mean outer diameter and the mean tracheal ring length in Group 4 were significantly greater than in the other groups. Mean outer diameter and mean tracheal ring length were significantly greater in Group 4 than in Group 1 at 12 and 16 weeks of age.

CONCLUSION

This study has shown that intra-tracheal administration of b-FGF enlarges the tracheal lumen.

Long-term follow-up of tracheal cartilage growth promotion by intratracheal injection of basic fibroblast growth factor

BACKGROUND

Intratracheal injection of basic fibroblast growth factor (b-FGF) has been shown to enlarge the tracheal lumen 4 weeks after treatment. The objective of this study was to investigate the long-term effect of tracheal cartilage growth promotion by intratracheal injection of b-FGF.

MATERIALS AND METHODS

New Zealand white rabbits were classified into four groups to receive either distilled water alone (Group 1; n = 16; control), 40 μg (Group 2; n = 10), 100 μg (Group 3; n = 13), or 200 μg (Group 4; n = 16) of b-FGF dissolved in water. The treatment was injected into the posterior wall of the cervical trachea using a tracheoscope. The animals were sacrificed 4 or 12 weeks later.

RESULTS

Four weeks after treatment, the mean luminal areas of tracheas for Groups 1, 2, 3, and 4 were 27.2, 25.6, 32.2, and 36.2 mm², respectively. At 12 weeks, these were 29.3, 37.9, 42.5, and 56.0 mm², respectively. The levels of glycosaminoglycan at 12 weeks were 93.9, 152.5, 123.2, and 210.6 μg/mg, respectively. At 12 weeks, the levels of type II collagen were 77.2, 133.1, 99.2, and 148.9 μg/mg, respectively.

CONCLUSION

Twelve weeks after a single injection of b-FGF, the mean luminal area of the trachea continued to increase.

Tracheal cartilage growth by intratracheal injection of basic fibroblast growth factor

BACKGROUND/PURPOSE

We have previously shown that intratracheal injection of slowly released (in gelatin) basic fibroblast growth factor (bFGF) significantly enlarged the tracheal lumen by a slight margin. This study aimed to investigate differences in tracheal cartilage growth by the intratracheal injection of bFGF doses in a rabbit model.

METHODS

Water (group 1; n=7; control) or 100μg (group 2; n=8) or 200μg (group 3; n=8) of bFGF dissolved in water was injected into the posterior wall of the cervical trachea of New Zealand white rabbits using a tracheoscope. All animals were sacrificed four weeks later.

RESULTS

The mean circumferences of cervical tracheas for groups 1, 2, and 3 were 18.8±0.83, 21.1±2.0, and 22.1±1.3mm, respectively. A significant difference was found between groups 1 and 2 (P=0.034) and groups 1 and 3 (P=0.004). The mean luminal areas of cervical tracheas for groups 1, 2, and 3 were 27.0±2.1, 32.2±4.8, and 36.3±4.6mm², respectively. A significant difference was found between groups 1 and 3 (P=0.001).

CONCLUSION

Intratracheal injection of bFGF in the dose range used significantly promoted the growth of tracheal cartilage in a rabbit model.

LEVELS OF EVIDENCE

Level II at treatment study (animal experiment).

Patch tracheoplasty in body tissue engineering using collagenous connective tissue membranes (biosheets)

BACKGROUND

Collagenous connective tissue membranes (biosheets) are useful for engineering cardiovascular tissue in tissue engineering. The aim was to evaluate the use of biosheets as a potential tracheal substitute material in vivo in a rabbit model.

METHODS

Group 1: Rectangular-shaped Gore-Tex (4×7mm) was implanted into a 3×6mm defect created in the midventral portion of the cervical trachea. Group 2: Rectangular-shaped dermis was implanted into a tracheotomy of similar size. Group 3: Biosheets were prepared by embedding silicone moulds in dorsal subcutaneous pouches in rabbits for 1month. Rectangular-shaped biosheets were implanted into a tracheotomy of similar size in an autologous fashion. All groups (each containing 10 animals) were sacrificed 4weeks after implantation.

MAIN RESULTS

All materials maintained airway structure for up to 4weeks after implantation. Regenerative cartilage in implanted Biosheets in group 3 was confirmed by histological analysis. Tracheal epithelial regeneration occurred in the internal lumen of group 3. There were significant differences in the amounts of collagen type II and glycosaminoglycan between group 3 and group 1 or 2.

CONCLUSION

We confirm that cartilage can self-regenerate onto an airway patch using Biosheets.