Multiple stimulation with spheroids comprising salivary gland and adipose-derived stem cells enhances regeneration of radiation-damaged salivary glands

Tissue engineering approaches using a single stem cell type have been unsuccessful in achieving regeneration of radiation-damaged salivary glands (SGs). Therefore, we combined adult SG stem cells (SGSCs) and adipose-derived stem cells (ASCs) in optimized spheroids to enhance the regeneration of damaged SGs in mice. SGSC/ASC spheroids survived longer and secreted more vascular endothelial growth factor (VEGF) than did SGSC spheroids. To enhance cell viability and differentiation, SGSC/ASC spheroids were stimulated with the Wnt/b-catenin signaling activator CHIR99021 and retinoic acid inhibitor BMS431 to maintain stemness. FGF7/10 induced the differentiation of multiple stimulated SGSC/ ASC spheroids. SGSC/ASC spheroids exhibited improved viability, calcium channel function, differentiation, and VEGF secretion after multiple, sequential stimulation. The 21-day survival rate of multiply stimulated SGSC/ASC spheroids was two-fold that of non-treated SGSC/ASC spheroids. Optimized SGSC/ASC spheroids enhanced the in vivo regeneration and functional recovery of SG tissue in mice by promoting neovascularization. Genes related to VEGF, such as Vegfa and Vegfb, were highly expressed 2-6 times for in vitro and 1.5 times for in vivo experiment in the multiply stimulated SGSC/ASC spheroids. Therefore, SGSC/ASC spheroids that have undergone multiple stimulation may be useful for healing radiation damaged SGs. (c) 2021 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

Automated summary

In this study, regeneration of radiation-damaged salivary glands (SGs) was enhanced by combining adult SG stem cells (SGSCs) and adipose-derived stem cells (ASCs) in spheroids. Multiple stimulations improved the viability, differentiation, and vascular endothelial growth factor (VEGF) secretion of SGSC/ASC spheroids, leading to increased in vivo regeneration and functional recovery of SG tissue in mice.