Live Cell Sorting of Differentiated Primary Human Osteoclasts Allows Generation of Transcriptomic Signature Matrix

Osteoclasts are specialized cells that degrade the bone matrix to create space for bone regeneration. During tumorigenesis, cancer cells metastasize to bone by disrupting bone's natural remodeling cycle. However, the mechanisms underlying critical bone-tumor interactions are poorly understood due to challenges in isolating osteoclasts from human bone. Thus, the conventional method to obtain osteoclasts for in vitro studies is via the differentiation of peripheral blood monocytes, which results in mixed cultures containing progenitor cells and osteoclasts of varying maturity and nuclearity. Presently, we hypothesized that the transcriptomic signatures of mature, multinucleated osteoclasts are distinct from osteoclasts with fewer nuclei. We established a live cell biomarker expression-based sorting protocol to allow purification of mature osteoclasts while maintaining viability and function. We observed that mature, multinucleated osteoclasts were transcriptomically distinct from those with fewer nuclei and that mature osteoclasts showed higher expression of genes that are associated with osteoclast fusion and function.