Administration of growth factors promotes salisphere formation from irradiated parotid salivary glands.

Vicky T Nguyen,Qionghui Zhang,Peter Dawson,Zoey Harris,Kirsten H Limesand

doi:10.1371/journal.pone.0193942

Abstract

Worldwide, 500,000 cases of head and neck cancer (HNC) are reported each year and the primary treatment for HNC is radiotherapy. Although the goal of radiotherapy is to target the tumor, secondary exposure occurs in surrounding normal tissues, such as the salivary glands. As a result, despite successful treatment of the cancer, patients are left with long-term side effects due to direct damage to the salivary glands. The effect is chronic and currently there is no treatment. Stem cells are an attractive therapeutic option for treatment of radiation-induced glandular dysfunction because of the potential to regenerate damaged cell populations and restore salivary gland function. However, limited knowledge about the endogenous stem cell population post irradiation hinders the development for stem cell-based therapies. In this study, an ex vivo sphere formation cell culture system was utilized to assess the self-renewal capacity of cells derived from parotid salivary glands at a chronic time point following radiation. Salivary glands from irradiated mice generate significantly fewer salispheres, but can be stimulated with fetal bovine serum (FBS) to generate an equivalent number of salispheres as unirradiated salivary glands. Interestingly, the number and size of salispheres formed is dependent on the concentration of FBS supplemented into the media. Salispheres derived from irradiated glands and cultured in FBS media were found to contain cells that proliferate and express progenitor and acinar cell markers such as Keratin 5, Keratin 14, Aquaporin 5, and NKCC1. Utilization of insulin-like growth factor (IGF1) injections following radiation treatment restores salivary gland function and improves salisphere generation. These findings indicate that stimulation of these cellular populations may provide a promising avenue for the development of cell-based therapies for radiation-induced salivary gland damage.

Highlights

Head and neck cancer (HNC) has more than 500,000 new cases worldwide [1]
Following a longer period of time in culture, the proliferation capacity of salispheres derived from untreated and irradiated cells significantly decreases, regardless of salisphere size (Fig 2C). These results suggest that decreased salisphere formation from irradiated glands may not be due to a decrease in cell viability, rather a subset population that is less responsive to proliferate in serum-free medium condition at early time points in culture
Since the majority of head and neck cancer (HNC) patients are adults and 4–6 week old mice could be defined as juveniles, we evaluated whether mice that were 8 weeks old at the time of radiation exhibited a similar phenotype when salisphere cultures were evaluated 30 days after radiation treatment

Summary

Introduction

Head and neck cancer (HNC) has more than 500,000 new cases worldwide [1]. The current treatment for HNC utilizes a multimodality approach, which includes surgery in combination with radiotherapy (RT) and chemotherapy [2]. HNC patients often suffer from permanent xerostomia following radiotherapy treatment [6]. Current preventive and palliative care for the management of RT-related xerostomia are limited and largely ineffective [7,8,9]. This poses a health concern because reductions in the quantity of saliva can greatly affect the quality of life of HNC patients. Such patients suffer from increased oral infection rates, difficulty chewing and swallowing food, malnutrition, and difficulty in speaking [10,11]

Methods

Results

Conclusion