Salivary gland tissue chip designed to screen preventative drugs for radiation-induced xerostomia

放射性口干症(口干综合症)是头颈部癌症常见的副作用。 患者由放射治疗引起的非靶点效应，即唾液腺受损。这种情况导致 导致营养不良、口腔感染、龋齿、说话困难和消化障碍等 并发症，约40%的患者。而FDA批准的预防这种情况的药物阿米福汀可以 对于患者，其临床应用是有限的，因为许多患者需要严重呕吐。 停止治疗。替代药物的发现因缺乏相关的体外模型而受阻，如 唾液腺细胞一旦离开人体，就会迅速丧失组织和分泌功能。 为了应对这一技术挑战，我们建议使用一种独特的系统来结合 微泡(MB)阵列技术与聚乙二醇(PEG)水凝胶形成良好的 唾液腺组织体外模拟生长的微环境。MBS是分开的球形空腔，带有 在聚二甲基硅氧烷(PDMS)中形成200微米的开口和~40 nL的体积。MB排列成一个阵列- 基于高通量筛选的格式和独特的球形形状已显示出集中 旁分泌/自分泌因子允许细胞调节自己的微环境。基质金属蛋白酶 (基质金属蛋白酶)-可降解的聚乙二醇大分子凝胶(1 mm×5 mm圆盘)已被证明可促进组织模拟 通过鼓励细胞-细胞和细胞-基质相互作用来构建和维持生物标记物的表达。 中心假设是这两种技术的结合将改善体外试验。 模拟唾液腺组织微环境，为高通量提供有效平台 放射性口干症预防药物的筛选。为了解决这一假设，有三个目标 已被确认身份。将开发芯片内分析方法来分析唾液腺组织的分泌功能 MBS中的模拟物(淀粉酶、粘蛋白、溶菌酶；目标1A)及其对辐射损伤的响应(caspase、 γH2AX，PrestoBlue™，EDU；AIM 1B)通过采用宏观(例如96孔板)分析/表征 技巧。目标2将确定为促进分泌功能提供指导性线索的蛋白质/肽 以及类似于天然唾液腺组织的组织，如在目标1A中开发的分析方法所测量的。 辐射防护药物的初步测试将在AIM 3进行，那里有一份选定的辐射防护药物清单 将通过MB水凝胶系统进行筛选，并与目前批准的治疗方法阿米福汀进行比较。 该项目对公共卫生具有重要意义，因为它将为新药提供重要的临床前测试 预防辐射引起的口干症。它将通过提供一个独特的高- 可适用于其他组织的药物筛选平台。

Radiation-induced xerostomia (dry mouth syndrome) is a common side effect in head and neck cancer patients caused by off-target effects of radiation therapy that damage the salivary glands. This condition leads to hyposalivation, oral infections, tooth decay, difficulty speaking, and impaired digestion, among other complications, in ~40% of patients. While amifostine, an FDA-approved drug to prevent this condition, can be administered to patients, its clinical usefulness is limited, as severe vomiting in many patients requires discontinuing treatment. Discovery of alternative drugs is hindered by a lack of relevant in vitro models, as salivary gland cells rapidly lose the organization and secretory function when removed from the body. To address this technological challenge, we propose the use of a unique system combining microbubble (MB) array technology with poly(ethylene glycol) (PEG) hydrogels to create a favorable microenvironment for salivary gland tissue mimetic growth in vitro. MBs are separated spherical cavities with 200 µm openings and ~40 nL volume formed in polydimethylsiloxane (PDMS). MBs are arranged in an array- based format for high-throughput screening and the unique spherical shape has been shown to concentrate paracrine/autocrine factors to allow cells to condition their own microenvironment. Matrix metalloproteinase (MMP)-degradable PEG macrogels (1 mm x 5 mm discs) have been shown to promote tissue mimetic structure and maintenance of biomarker expression through encouraging cell-cell and cell-matrix interactions. The central hypothesis is that the combination of these two techniques will improve the in vitro microenvironment of salivary gland tissue mimetics and provide an effective platform for high-throughput screening of preventative drugs for radiation-induced xerostomia. To address this hypothesis, three aims have been identified. In-chip assays will be developed to analyze the secretory function of salivary gland tissue mimetics in MBs (amylase, mucins, lysozyme; Aim 1A) and their response to radiation damage (caspase, γH2AX, PrestoBlue™, EdU; Aim 1B) by adapting macroscale (e.g. 96-well plate) assays/characterization techniques. Aim 2 will identify proteins/peptides that provide instructive cues for promoting secretory function and organization similar to native salivary gland tissue, as measured by assays developed in Aim 1A. Preliminary testing of radioprotective drugs will occur in Aim 3, where a selected list of radioprotective drugs will be screened through the MB-hydrogel system and compared to amifostine, the currently approved therapy. This project is significant for public health, as it will provide important preclinical testing for new drugs to prevent radiation-induced xerostomia. It will impact the research community by providing a unique high- throughput drug screening platform that can be adapted for other tissues.