The problem. Clinical pathology leans on immunohistochemistry, which typically visualises one or two markers per section. Understanding a tumor microenvironment — which immune cells sit where, in what activation state — needs many proteins measured together on the same FFPE tissue that hospitals already archive. The challenge is doing that with the sensitivity and dynamic range clinical samples demand.

The idea. MIBI stains tissue with antibodies tagged by pure elemental-metal isotopes, then uses a focused ion beam (secondary ion mass spectrometry) to sputter the section and quantify the metals released at each position. Because metal isotopes are counted rather than fluorescence read, it reaches roughly 100 possible channels with high dynamic range, imaging the labelled proteins at subcellular resolution across a tumor section.

Why it matters. MIBI and imaging mass cytometry arrived in the same year with the same core insight — metal tags plus mass detection — and together they define spatial proteomics, exactly the modality the STU pairs with spatial transcriptomics. Its explicit focus on human tumor tissue and FFPE compatibility is what makes it translational, connecting the reading to the clinical-spatial benchmarks already on the list.

Verdict. A foundational platform for tissue proteomics with a clinical bent; instrument access is specialised and acquisition is slow. Read it as the ion-beam route to the same goal imaging mass cytometry chases — the proteome, mapped in place.