Tissue-engineered larynx using perfusion-decellularized technique and mesenchymal stem cells in a rabbit model.

CONCLUSION: Reseeding mesenchymal stem cells (MSCs) into the decellularized laryngeal muscle matrix for construction of a tissue-engineered larynx is feasible. This in vivo maturation in the omentum could be the first step before in situ implantation of the construct. This construct could facilitate a tissue-engineered method for laryngeal reconstruction. OBJECTIVES: The extracellular matrix (ECM) and MSCs have been widely used for organ reconstruction. Our study aimed to prepare a soft tissue decellularized laryngeal scaffold with intact laryngeal cartilages utilizing a perfusion-decellularized technique, reseeding cells on it, and then construct a recellularized larynx. METHODS: Perfusion-decellularized larynges were obtained from 20 rabbits by perfusion of the common carotid arteries with detergents. Twelve perfused larynges were observed by macroscopic visualization, histological examination, scanning electron microscopy (SEM), and cartilage viability. The remaining eight perfusion constructs were reseeded with induced MSCs aspirated from eight receptor rabbits. Composites were transferred into greater omentums of receptor rabbits after adherence for 1 day in vitro. Rabbit larynges were harvested after 4 weeks and 8 weeks, respectively. Macroscopic visualization, histological examination, and immunohistochemistry were performed. RESULTS: Larynges perfused by sodium dodecyl sulfate became transparent after 2 h of perfusion. Histology and SEM indicated that the perfusion method showed a better decullularized effect. Almost no intact cells or nuclei were found, while more pores and collagen fibers were retained in the decellularized matrix. The chondrocyte vitality assay indicated that chondrocyte vitality was high. Vascularization was clearly seen by 4 weeks and relatively integrated cartilage frameworks remained by 8 weeks. Histological and immunohistochemical examinations clearly showed muscle bundles and vessels.

Androgen-induced proliferation in the developing larynx of Xenopus laevis is regulated by thyroid hormone.

Exposure to exogenous androgen regulates cell number in the developing larynx of Xenopus laevis and hormone-regulated laryngeal development requires secretion of thyroid hormone (TH). We sought to determine whether exposure to TH is both sufficient and necessary for androgen-evoked cell proliferation (androgen competency) in developing larynx. Androgen competency was not observed in the premetamorphic larynx (tadpole stage 53, before TH secretion) but was present just prior to metamorphic climax (stage 58, during TH secretion). However, when TH is administered precociously (between stages 48 and 50), androgen competency can be observed at stage 53. The stage 52 larynx expresses high levels of the mRNA for TH receptor alpha. The duration of TH exposure required at tadpole stage 48 is greater than 2 days; studies in juveniles indicate that TH exposure need not be maintained in order for androgen competency to persist. The effects of exposure to TH on androgen competency are long lasting and perhaps permanent. While organotypic cultures obtained from tadpoles during premetamorphosis (stage 52) can proliferate in vitro and proliferation is augmented by TH exposure as it is in vivo, precocious exposure to TH does not induce androgen competency. In contrast, androgen does evoke cell proliferation in cultures obtained from metamorphosing (stage 58) tadpoles; proliferation is confined to the cartilage component. Thus, unlike larynges in vivo, muscle will not proliferate in response to androgen, indicating the necessity for an additional factor not present in vitro. Androgen receptor mRNA expression, believed required for androgen competency, was assessed in vivo and in vitro. The tadpole larynx strongly expresses AR mRNA, expression does not require exposure to TH nor is expression diminished in culture.

[The determination of the earliest signs of cell damage after translaryngeal intratracheal long-term intubation in rabbits. A light- and electron-microscopic study]. / Licht- und elektronenmikroskopische Untersuchungen zur Ermittlung des frühesten Schädigungszeitpunktes nach translaryngealer intratrachealer Langzeitintubation beim Kaninchen.

Eighteen New Zealand rabbits were artificially respired, orotracheally with a cuff pressure of approximately 35 mm Hg, for between 2 and 36 h. After 2 h artificial respiration cell degeneration was seen in the area of the cuff, above the cartilage rings, in the form of cytoplasmic degeneration. After a 4 h intubation period an epithelial loss was seen. The basal membrane was intact. A connective tissue oedema, which was limited to the region of the epithelial lesion, became more wide-spread over the 36 h of intubation. A well-developed ulcer could be identified under the light microscope after 36 h. Increased mucous production as well as an increase in bacteria could be observed after 4 h. At no time could a degeneration of the cartilage be seen in the electron micrographs. The intercartilaginous area also remained free from cell degeneration although signs of vascular congestion could be seen.