Cell Lineage Tracing: Colocalization of Cell Lineage Markers with a Fluorescent Reporter

Cell lineage tracing, an old technique which originated in the nineteenth century, regains popularity and relevance due to introduction of a more sensitive tomato fluorescent protein under the control of a ubiquitous promoter (Rosa 26 gene). In addition, various tissue specific CreERT2 mouse lines are widely available, making cell lineage tracing studies more specific and powerful. In this protocol, we provide a practical guide for researchers to map progeny of specific cells such as chondrocytes during development using a fluorescent reporter (tomato, red) and multiple chondrocyte Cre lines. Further, we provide valuable examples in which these tracing lines, combined with a bone reporter mouse line (2.3 Col 1a1-GFP) or costained with different immunofluorescent proteins, revealed how a chondrocyte transdifferentiates into a bone cell in vivo.