Pancreatic ductal adenocarcinoma (PDAC) is characterized by its fibrotic and stiff extracellular matrix. However, how the altered cell/extracellular-matrix signalling contributes to the PDAC tumour phenotype has been difficult to dissect. Here we design and engineer matrices that recapitulate the key hallmarks of the PDAC tumour extracellular matrix to address this knowledge gap. We show that patient-derived PDAC organoids from three patients develop resistance to several clinically relevant chemotherapies when cultured within high-stiffness matrices mechanically matched to in vivo tumours. Using genetic barcoding, we find that while matrix-specific clonal selection occurs, cellular heterogeneity is not the main driver of chemoresistance. Instead, matrix-induced chemoresistance occurs within a stiff environment due to the increased expression of drug efflux transporters mediated by CD44 receptor interactions with hyaluronan. Moreover, PDAC chemoresistance is reversible following transfer from high- to low-stiffness matrices, suggesting that targeting the fibrotic extracellular matrix may sensitize chemoresistant tumours. Overall, our findings support the potential of engineered matrices and patient-derived organoids for elucidating extracellular matrix contributions to human disease pathophysiology.

胰腺导管腺癌（PDAC）的特点是其纤维化和僵硬的细胞外基质。然而，改变的细胞/细胞外基质信号传导如何影响 PDAC 肿瘤表型一直难以剖析。在这里，我们设计和工程矩阵，概括了 PDAC 肿瘤细胞外基质的关键特征，以解决这一知识差距。我们发现，来自三名患者的 PDAC 类器官在与体内肿瘤机械匹配的高硬度基质中培养时，会对几种临床相关化疗产生耐药性。使用遗传条形码，我们发现虽然发生基质特异性克隆选择，但细胞异质性并不是化学耐药性的主要驱动因素。相反，由于 CD44 受体与透明质酸相互作用介导的药物外流转运蛋白表达增加，基质诱导的化学耐药性发生在僵硬的环境中。此外，PDAC 化疗耐药性在从高硬度基质转移到低硬度基质后是可逆的，这表明靶向纤维化细胞外基质可能会使化疗耐药肿瘤变得敏感。总体而言，我们的研究结果支持工程基质和患者来源的类器官在阐明细胞外基质对人类疾病病理生理学的贡献方面的潜力。