Autologous Muscle-Derived Cell Therapy for Swallowing Impairment in Patients Following Treatment for Head and Neck Cancer

Longitudinal Effects of Base of Tongue Concurrent Chemoradiation Therapy in a Pre-Clinical Model

BACKGROUND/OBJECTIVES

Base of tongue (BOT) dysfunction is common following oropharyngeal concurrent chemoradiation therapy (CCRT). We present a clinically relevant animal model quantifying the effects of CCRT on tongue strength and elasticity over time.

METHODS

Fifty-three male and 53 female Sprague-Dawley rats were randomized to control or experimental groups. Experimental animals received cisplatin, 5-fluorouracil, and 5 fractions of 7 Gy directed to the BOT. Controls received no intervention. At 2 weeks, 5 months, or 10 months after CCRT, animals underwent non-survival surgery to measure twitch and tetanic tongue strength, which were analyzed using multivariate linear mixed effects models. Tongue displacement, a surrogate for tongue elasticity, was also determined via stress-strain testing and analyzed via a multivariate linear mixed effects model.

RESULTS

Reporting the combined results of both sexes, the estimated experimental group mean peak twitch forces became more divergent over time compared to controls, being 8.3% lower than controls at 2 weeks post-CCRT, 15.7% lower at 5 months, and 31.6% lower at 10 months. Estimated experimental group mean peak tetanic forces followed a similar course and were 2.9% lower than controls at 2 weeks post CCRT, 20.7% lower at 5 months, and 27.0% lower at 10 months. Stress-strain testing did not find CCRT to have a significant effect on tongue displacement across experimental timepoints.

CONCLUSIONS

This study demonstrates an increasing difference in tongue strength over time between controls and animals exposed to CCRT. Tongue elasticity was not significantly affected by CCRT, suggesting that changes in strength may not be caused by fibrosis.

LEVEL OF EVIDENCE

NA Laryngoscope, 133:1455-1461, 2023.

Muscle Regeneration of the Tongue: A review of current clinical and regenerative research strategies

Various abnormalities of the tongue, including cancers, commonly require surgical removal to sequester growth and metastasis. However, even minor resections can affect functional outcomes such as speech and swallowing, thereby reducing quality of life. Surgical resections alone create volumetric muscle loss whereby muscle tissue cannot self-regenerate within the tongue. In these cases, the tongue is reconstructed typically in the form of autologous skin flaps. However, flap reconstruction has many limitations and unfortunately is the primary option for oral and reconstructive surgeons to treat tongue defects. The alternative, but yet undeveloped strategy for tongue reconstruction is regenerative medicine, which widely focuses on building new organs with stem cells. Regenerative medicine has successfully treated many tissues, but research has inadequately addressed the tongue as a vital organ in need of tissue engineering. In this review, we address the current standard for tongue reconstruction, the cellular mechanisms of muscle cell development, and the stem cell studies that have attempted muscle engineering within the tongue. Until now, no review has focused on engineering the tongue with regenerative medicine, which could guide innovative strategies for tongue reconstruction.