Platelet-rich plasma(PRP), is a concentrate of platelet-rich plasma protein derived from whole blood. The main components of it are platelets, leukocytes and fibrin. Autologous PRP treatment can avoid the immune rejection caused by exogenous growth factor and the spread of disease. Evidence of the efficacy and safety of PRP has been proven in many studies. Benign central airway stenosis is characterized by airway compromise involving the larynx, trachea, or bronchi and will lead to devastating consequences. Unfortunately, the incidence of this disease is increasing steadily. As most important treatment for benign airway stenosis, respiratory intervention has become one of the most common treatments to fight the disease. However, the restenosis caused by tissue hyperplasia, wound repair and scar formation after treatment is still common, which remains the limitation of respiratory intervention. Long-term efficacy of repeated interventional treatment is unsatisfying, too. Several studies have discovered similar mechanism between stenosis of tracheal to hyperplastic scar of skin, both of which are relative with deep structure injury such as the intrinsic layer of airway mucosa. PRP has shown significant efficacy for hyperplastic scar of skin. Correspondingly, PRP will be applied as treatment of refractory benign airway stenosis to reduce restenosis by inhibit the formation of granulation.

Inclusion Criteria:

1. Subjects with aged between 18 to 75
2. Subjects diagnosed with refractory benign airway stenosis and meet the following conditions: a. Received two or more (including two) interventional treatments such as laser, high-frequency electrosurgical unit, argon plasma coagulation (APC), cryotherapy, balloon dilation, and metal stent placement. b. Restenosis within 1 month after more than 2 times interventional treatments suffering from repeated granulation hyperplasia of wound
3. Subjects tolerant to bronchoscope；
4. Subjects signed informed consent

Exclusion Criteria:

1. Subjects with airway disease:congenital benign central airway stenosis, recurrent polychondritis, etc;
2. Subjects with the following pulmonary diseases: asthma, active pulmonary tuberculosis, pulmonary embolism, pneumothorax, pulmonary hypertension, etc;
3. Subjects with malignant tumors or have a history of malignant tumors;
4. Subjects with uncontrolled systemic infection;
5. Subjects requiring anti-clotting drugs;
6. Subjects with myocardial infarction, unstable angina, liver cirrhosis, acute glomerulonephritis, etc;
7. Subjects with syphilis, HIV,HBV,HCV antibody positive;
8. Subjects with Coagulation disorders such as hemophilia, giant platelet syndrome, thromboasthenia, etc;
9. Subjects with severe renal damage, serum creatinine is more than 1.5 times the upper limit of the normal value;
10. Subjects with liver disease or liver damage: ALT,AST, total bilirubin > 2 times the upper limit of the normal value;
11. Subjects with a history of psychosis or suicide or epilepsy or other central nervous system diseases;
12. Subjects with severe arrhythmias(e.g. ventricular tachycardia, frequent supraventricular tachycardia, atrial fibrillation, atrial flutter, etc.) or degree II above abnormal conduction;
13. Subjects allergic to thrombin;
14. Subjects accepted by any other clinical study within the first three months of the study;
15. Subjects with poor compliance;
16. Any other conditions might increase the risk of the patient or interfere with the clinical study.