An easy and reproducible method for rapid tissue macroarray block construction

Tissue macroarrays (Macro-TA), with 3-6 mm tissue cores, are an alternative to Tissue Microarrays for small case cohorts, enhanced area selection, and spatial transcriptomics. Still, Macro-TA construction methods are time-consuming and have orientation challenges. We present a method for fast Macro-TA construction ensuring precise tissue orientation. Donor paraffin blocks matching HE slides were arranged using a layout for case identification. A punch biopsy was used to both perforate a sponge used as a scaffold and to extract tissue cores from donor paraffin blocks. Tissue cores were sequentially inserted into the sponge holes following the layout. Depending on the punch diameter, Macro-TAs contained 9 to 48 cores. Each Macro-TA block was constructed in 4 to 25 min. This is a new, fast, easy, and reproducible method for Macro-TA construction without specialized instrumentation. It reduces 10× the processing time, ensuring proper sample orientation and being easy to implement for diagnostic and research pathology purposes.