Reprogramming the pancreatic tumor microenvironment using smart stem cells: A new frontier in cancer therapy

Pancreatic ductal adenocarcinoma (PDAC) is among the most aggressive cancers (5-year survival <12%), and its complexity and great resistance to treatment are partially explained by the complex tumor microenvironment (TME). The thick desmoplastic stroma, composed of cancer-associated fibroblasts, extracellular matrix molecules, immune-suppressive cells, and an abnormal vasculature, forms physical and biochemical barriers that restrict drug delivery and immune cell invasion. The traditional treatments, which focus on one or more elements of the TME, have not been very successful, with stromal elements showing context-specific functions and dynamic interactions. As such, there is an increasing demand for integrative approaches to therapy that aim at functional remodelling rather than tumour stroma depletion. Herein, we provide a systems-level view of how engineered or smart stem cells could be used to reconstruct the PDAC microenvironment. These stem cell systems already have inbuilt tumor-homing capacity and may be genetically or bio-materials-engineered to provide therapeutic factors in a regulated, tumor-responsive manner. Some of the major pathways that participate in TME reorganization, such as fibroblast reprogramming, extracellular matrix normalization, reestablishment of vascular function, and reactivation of anti-tumor immunity, are discussed. Moreover, we present new strategies, including feedback-responsive gene circuits, cytokine delivery systems, and combination strategies that integrate stem cell therapy with other conventional treatments. Lastly, we discuss existing translation issues, including delivery efficiency, safety considerations, and differences in clinical responses, and describe future trends toward biomarker-directed and patient-centered treatment. Altogether, smart stem cell-based solutions represent a promising platform for transforming the PDAC microenvironment into a treatment-responsive and therapy-resistant role.