Regenerative medicine approach to reconstruction of the equine upper airway.

Airway obstruction is a common cause of poor performance in horses. Structural abnormalities (insufficient length, rigidity) can be a cause for the obstruction. Currently, there are a few effective clinical options for reconstruction of the equine larynx. A regenerative medicine approach to reconstruction may provide the capability to stabilize laryngeal structures and to encourage restoration of site-appropriate, functional, and host-derived tissue. The purpose of this study was the histopathological evaluation of (1) decellularization of equine (horse) laryngeal cartilages (epiglottis and arytenoids); (2) the host response to decellularized laryngeal cartilages implanted subcutaneously in a donkey model as a test of biocompatibility; and (3) the use of decellularized laryngeal cartilages in a clinically relevant pilot study in the horse larynx. Equine laryngeal cartilages were found to be sufficiently decellularized and were subsequently implanted subcutaneously in donkeys to test biocompatibility. After 4 weeks, the implanted cartilage was harvested. In the subcutaneous model, the samples did not elicit a rejection or foreign body type reaction and were judged suitable for implantation in a clinically relevant equine model. Implants were placed in the upper airway (arytenoids and epiglottis) of one horse. At 4 weeks, the implants were observed to remodel rapidly and were replaced by dense connective tissue with signs of new hyaline cartilage formation in the arytenoids and by connective tissue containing glandular structures and an epithelial covering in the epiglottis. The results of the present study demonstrate the feasibility of a scaffold-based regenerative medicine approach to reconstruction of the equine upper airway; however, further studies investigating long-term integration, formation of new cartilage, and mechanical properties are needed.

[Sternum-hyoid muscle transposition and arytenoid adduction for unilateral vocal cord paralysis].

OBJECTIVE: To explore the therapeutic effect of sternum-hyoid muscle transposition and arytenoid adduction for unilateral vocal cord paralysis (UVCP). METHODS: Included in this study were 19 patients with UVCP lasted for 12 months to 15 years. The surgical technique was as follows. The thyroid cartilage was engaged with a skin hook and gently rotated anteriorly. The lateral-inferior corner of the thyroid cartilage was exposed and the muscular process of the arytenoid was identified. Then, the thyroid lamina on the involved side was parasagittally separated 5 mm off the midline. The inner perichondrium was carefully freed from the overlying thyroid cartilage. The lamina was retracted laterally, and a 3-0 prolene suture was placed through the muscular process and tied to the cricoid cartilage at the origin of the lateral cricoarytenoid muscle. A bipedicled strap muscle flap was then transposed into the space between the lamina and the inner perichondrium. Pre- and postoperative voice evaluations measured mean fundamental frequency, jitter, shimmer, harmonic ratio and maximal phonation time, as well as assessments of voice quality. RESULTS: Vocal improvement was obtained in 100% (19 of 19) of patients. Immediately after the operation, the ingression could be observed in vocal cord membrane and vocal process, vocal cord volume was amplified. There was a significant difference (P < 0.05) in all parameters (fundamental frequency, jitter, shimmer, harmonic ratio and maximal phonation time) between pre- and postoperative voice evaluations measured mean. There was no significant difference (P > 0.05) in voice evaluations measured mean between 2 months and 12 months after operation in all patients. No major complications were noted in any patient. CONCLUSION: Sternum-hyoid muscle transposition and arytenoid adduction for unilateral vocal cord paralysis is simple and convenient, no immune rejection, and the long-term result is stable.