[Effects of different time of cryoablation on the proliferation of airway traumatic granuloma and its mechanism in rabbits].

Objective

To investigate the effect of different cryoablation time on tracheal traumatic granulation formation and its mechanism.

Methods

A total of 32 rabbits were randomly assigned into four groups (A-D). Group A underwent tracheotomy alone. Group B, C and D received intra-tracheal brush rubbing to establish airway granulation model. Group C and D underwent 30 s and 2-minute cryoablation respectively. Tracheal specimens of all groups were collected to examine pathological changes using HE staining. Levels of transforming growth factor beta 1 (TGF-β(1)) and CD34 in tracheal granulation were evaluated using immunohistochemistry (IHC) and real-time quantitative reverse transcription polymerase chain reaction (RT-qCR).

Results

Tracheal lumens of group A were smooth without granulation. While the growth of granulation and luminal stenosis were most severe in Group B, followed by Group D and C. Submucosa thickness of Group B was largest as compared with other groups (0.20±0.07, 0.77±0.28, 0.44±0.13 and 0.55±0.18 mm for Group A to D, respectively. P<0.05). And the submucosa layer of Group C was thinner than Group D (P<0.05). The expression and transcription levels of TGF-β(1) of trachea were highest in Group B as detected by IHC and RT-qPCR (P<0.05), followed by Group D and C (IHC: 0.48±0.01 vs 0.43±0.01, P<0.05; RT-qPCR: 12.61±2.14 vs 2.38±0.10, P<0.05). Both protein and mRNA levels of CD34 were highest in Group B as detected by IHC and RT-qPCR (P<0.05). Tracheal mRNA levels of CD34 were more abundant in Group D than Group C (4.92±0.90 vs 2.09±0.10, P<0.05), while no significant difference was found between groups regarding protein levels measured by IHC.

Conclusions

Cryoablation could alleviate the hyperplasia of tracheal traumatic granulation, possibly due to the inhibition of TGF-β(1) and CD34 expression. The effect of 30 s cryoablation for tracheal traumatic granulation is better.