Microfluidic-Based Scratch Assays for Wound Healing Studies: A Systematic Review.

Cell migration plays a central role in physiological processes such as wound healing, tissue regeneration, and immune responses, as well as in pathological conditions like chronic inflammation and tumor metastasis. Among the in vitro approaches to study this phenomenon, the conventional wound healing assay (scratch assay) has been widely used due to its simplicity and low cost. However, its limitations, including poor reproducibility, damage to the extracellular matrix (ECM), and lack of dynamic physiological conditions, have prompted the development of microfluidic alternatives. Scratch-on-a-chip platforms integrate engineering and microtechnology to provide standardized, non-destructive methods for wound generation, preserve ECM integrity, and allow precise control of the cellular microenvironment. These systems also enable miniaturization, reducing reagent and cell consumption, while facilitating the application of biochemical or physical stimuli and real-time monitoring. This review synthesizes advances reported in the literature, addressing the different wound induction strategies (enzymatic depletion, physical depletion, and physical exclusion), the role of ECM composition, and the impact of mechanical forces such as shear stress. Overall, scratch-on-a-chip assays emerge as promising tools that enhance reproducibility, better mimic in vivo conditions, and broaden applications for therapeutic testing and mechanistic studies in cell migration.