The In Vitro Wound-Scratch Assay: Applications, Technical Advances, and Limitations in Wound Healing Research.

Area of Science:

• Cell Biology
• Biomedical Engineering
• Wound Healing Research

Background:

• The wound-scratch assay is a common in vitro method for studying collective cell migration, crucial for wound closure.
• Its simplicity and adaptability make it a foundational tool for early wound healing research and drug screening.
• The assay involves creating a gap in a cell layer and observing closure over time.

Purpose of the Study:

• To review technical advancements in wound-scratch assay methods.
• To critically evaluate the biological limitations of the wound-scratch assay in representing in vivo wound repair.
• To assess the implications for therapeutic screening.

Main Methods:

• A narrative review of 199 published studies, identifying 73 relevant to wound healing.
• Categorization of wound creation methods into mechanical, semi-automated, and fully-automated approaches.
• Analysis of the assay's biological constraints and comparison with in vivo wound repair processes.

Main Results:

• A technical hierarchy of wound creation methods was identified, ranging from manual to automated systems.
• The assay primarily models planar cell migration, neglecting key in vivo processes like inflammation and vascularization.
• Preliminary data suggest that compounds with known in vivo wound healing activity may show underestimated effects in this assay.

Conclusions:

• While technical improvements enhance reproducibility, the wound-scratch assay has inherent biological limitations.
• The assay may underestimate or misclassify the therapeutic potential of compounds targeting complex wound repair pathways.
• The wound-scratch assay remains a valuable hypothesis-generating tool when interpreted cautiously and integrated with complementary models.