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

放射线引起的口干症（口干综合征）是头颈部癌症常见的副作用 由放射治疗的脱靶效应引起的损伤唾液腺的患者。这种情况导致 唾液分泌不足、口腔感染、蛀牙、说话困难和消化不良等 并发症，约40%的患者。而amifostine，FDA批准的药物，以防止这种情况下，可以 给患者服用，其临床用途是有限的，因为许多患者的严重呕吐需要 停止治疗。替代药物的发现受到缺乏相关体外模型的阻碍， 唾液腺细胞在从体内取出时迅速失去组织和分泌功能。 为了应对这一技术挑战，我们建议使用一种独特的系统， 微泡（MB）阵列技术与聚（乙二醇）（PEG）水凝胶，以创造一个有利的 唾液腺组织体外模拟生长的微环境。MB是分离的球形空腔， 在聚二甲基硅氧烷（PDMS）中形成200 µm开口和约40 nL体积。MB排列成阵列- 基于格式的高通量筛选和独特的球形形状已被证明集中 细胞可以通过旁分泌/自分泌因子调节自身的微环境。基质金属蛋白酶 已经显示，MMP-可降解的PEG大凝胶（1 mm x 5 mm圆盘）促进组织模拟。 通过促进细胞-细胞和细胞-基质相互作用来构建和维持生物标志物表达。 中心假设是，这两种技术的组合将改善体外细胞培养。 唾液腺组织模拟物的微环境，并为高通量 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 被识别。芯片内分析将被开发用于分析唾液腺组织的分泌功能 MB中的模拟物（淀粉酶、粘蛋白、溶菌酶; Aim 1A）及其对辐射损伤的反应（半胱天冬酶， γ H2 AX，PrestoBlue™，EdU; Aim 1B），通过调整大规模（例如96孔板）测定/表征 技术.目标2将鉴定为促进分泌功能提供指导性线索的蛋白质/肽 和类似于天然唾液腺组织的组织，如通过Aim 1A中开发的测定所测量的。 将在目标3中对辐射防护药物进行初步测试， 将通过MB-水凝胶系统进行筛选，并与目前批准的治疗药物氨磷汀进行比较。 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- 这是一个可以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.