The AC femur-tibia joint tissue from 4 Grem1-CreErt mice were shaved with a scalpel under the microscope, and then enzymatically digested with 4mg/ml Collagenase ii (Worthington Biochemical Corporation, LS004176) in alphaMEM (#M5650, Sigma) for 1h at room temperature and filtered with a 75um strainer to achieve single cells suspension and labeled with DAPI and kept on ice. Single cell suspensions were sorted by fluorescence activated cell sorting based forward and side scatter, dTomato fluorescence (positive) and DAPI (negative). Sorted cells were collected in Alpha-Mem media and submitted to the Sulzberger Columbia Genome Center at Columbia University Irving Medical Center for library preparation and sequencing. Library preparation was performed using Chromium Single Cell 3' Library & Gel Bead Kit v3