Nanoscale imaging of clinical specimens using pathology-optimized expansion microscopy

Area of Science:

• Biomedical Engineering
• Pathology
• Microscopy

Background:

• Expansion microscopy (ExM) enhances light microscopy resolution but hasn't been applied to clinical tissue samples.
• Clinical tissue processing (formalin fixation, paraffin embedding, H&E staining) is incompatible with standard ExM protocols.

Purpose of the Study:

• To develop and validate a clinically optimized ExM method for nanoscale imaging of diverse human tissue samples.
• To demonstrate the utility of this method, termed expansion pathology (ExPath), in clinical diagnostics and research.

Main Methods:

• Developed ExPath by adapting ExM protocols for formalin-fixed, paraffin-embedded, and fresh-frozen clinical samples.
• Incorporated protein anchoring and mechanical homogenization steps optimized for clinical tissues.
• Utilized conventional microscopes with standard reagents for imaging biomolecules at ~70-nm resolution.

Main Results:

• ExPath successfully enabled nanoscale imaging of diverse biomolecules in intact human tissues.
• Applied ExPath for optical diagnosis of kidney minimal-change disease, replacing electron microscopy.
• Achieved high-fidelity computational discrimination between early breast neoplastic lesions, aiding pathologist consensus.

Conclusions:

• ExPath provides a viable method for nanoscale imaging of routine clinical tissue samples.
• This technique has the potential to enhance diagnostic accuracy and facilitate pathological research.
• ExPath may lead to the routine integration of nanoscale imaging in clinical pathology workflows.