Simultaneous quantification of a plurality of proteins in a user-defined region of a cross-sectioned tissue

A method of producing a spatially-resolved profile of protein abundance in a tissue sample comprising:

• a) contacting the tissue sample with a solution comprising at least 15 species of probes, the probes comprising a target-binding domain, a signal oligonucleotide, and a photo-cleavable motif located between the target-binding domain and the signal oligonucleotide,
• wherein each species of probe comprises a unique protein target-binding domain that hybridizes to one of the at least 15 target proteins and a unique signal oligonucleotide specific for the target protein;
• b) illuminating a first location of the tissue sample with light sufficient to release signal oligonucleotides at the first location;
• c) collecting the signal oligonucleotides released in step (b) from the solution proximal to the first location;
• d) identifying and quantifying via multiplexed immunohistochemistry the signal oligonucleotides collected in step (c), thereby determining the abundance of the at least 15 target proteins in the first location;
• e) illuminating at least a second location of the tissue sample with light sufficient to release the signal oligonucleotides at the at least second location;
• f) collecting the signal oligonucleotides released in step (e) from the solution proximal to the at least second location;
• g) identifying and quantifying via multiplexed immunohistochemistry the signal oligonucleotides collected in step (f), thereby determining the abundance of the at least 15 target proteins in the at least second location;
• and
• h) comparing the abundance of the at least 15 target proteins in the first location of the tissue sample to the abundance of the at least 15 target proteins in the at least second location of the tissue sample, thereby generating a spatially-resolved profile of protein abundance in the tissue sample.