Preparation of Human Chondrocytes for Profiling Using Cytometry by Time-of-flight (cyTOF)

Single-cell technologies have allowed high-resolution profiling of tissues and thus a deeper understanding of tissue homeostasis and disease heterogeneity. Understanding this heterogeneity can be especially important for tailoring treatments in a patient-specific manner. Here, we detail methods for preparing human cartilage tissue for profiling via cytometry by time-of-flight (cyTOF). We have previously utilized this method to characterize several rare cell populations in cartilage, including cartilage-progenitor cells, inflammation-amplifying cells (Inf-A), and inflammation-dampening cells (Inf-D). Previous bio-protocols have focused on cyTOF staining of PBMCs. Therefore, here we detail the steps unique to the processing of human cartilage and chondrocytes. Briefly, cartilage tissue is digested to release individual chondrocytes, which can be expanded and manipulated in culture. These cells are then collected and fixed in preparation for cyTOF, followed by standard staining and analysis protocols.