Table 2. Nerve tissue engineering technology in RLNI animal models.

Experiment (reference)	Animal model	Experiment duration	Ingredient	Operation	Result	Conclusion
Şentürk et al. (55)	Rats	16 weeks	PGA-coated tube	The tube was inserted into two nerve stumps and immobilized with 8/0 PGA suture material	Compared with other groups (only transect, primary repair with 8/0 polypropylene), vocal cord mobility was proportionally higher in the experimental group	The conduit offered a microenvironment conducive to accurate orientation of nerve fibers
Li et al. (56)	Rats	12 weeks	SCs, NSCs, laminin-chitosan-PLGA nerve conduit	Five-mm-long laminin-chitosan-PLGA nerve conduit was sutured between nerve stumps. There was a 5-mm gap between the stumps	Compared with other groups (SCs only, NSCs only, null), the diameter and area of axon regeneration, the cytokine secretion was better in the experimental group. The recovery of vocal cord motion was similar between the experimental group and the autograft group, better than other groups	The repair effect of SCs and NSCs in the laminin-chitosan-PLGA nerve conduit was best in the article, even better than the autograft group
Choi et al. (57)	Rabbits	8 weeks	PCL/F127 nerve guide conduit	PCL/F127 nerve guide conduit was sutured between a 10-mm nerve gap	Compared with the silicone tube group, vocal cord movement, thyroarytenoid muscle status, and nerve regeneration were all better	The conduit prevented the influence of fibrous scar tissue for nerve regeneration, but guaranteed nutrients and oxygen penetration. Thus, it promoted nerve regeneration
Wang et al. (58)	Rats	12 weeks	BDNF, GDNF, LBDs, collagen tube	The tube was immobilized in a 5-mm nerve gap. A mixture with Matrigel, laminin, LBD-BDNF and LBD-GDNF was injected into the tube	Compared with the autologous nerve graft group, the nerve fiber regeneration, muscle action potentials and vocalization were better in the experimental group	The drug delivery system was superior to autologous nerve grafting in RLNI
Yoshimatsu et al. (59)	Rats	8 weeks	RADA16-I hydrogels, silicone tube	An 8-mm silicone tube bridged a 6-mm nerve gap. The experimental group tube was injected with RADA16-I hydrogel	Compared with other groups (no RADA16-I, neurectomy only), the number of myelinated nerves was higher and the area of thyroarytenoid muscle was large in the experimental group	The RADA16-I hydrogel has potential for RLN regeneration

RLNI, recurrent laryngeal nerve injury; PGA, polyglycolic acid; SCs, Schwann cells; NSCs, neural stem cells; PLGA, poly-lactic-co-glycolic acid; PCL/F127, polycaprolactone/pluronic F127; BDNF, brain-derived neurotrophic factor; GDNF, glial cell line-derived neurotrophic factor; LBDs, laminin-binding domains; RADA16-I, a self-assembling peptide.