Single cell level characterization of immune cells in 10-week-old C57BL/6 knee joints and femur bone marrow

Post-traumatic Osteoarthritis (PTOA) occurs in about half of individuals who sustained articular injuries including tibial plateau fracture, meniscus tear, or an anterior cruciate ligament (ACL) rupture. We utilize a noninvasive tibial compression injury (TCI) model that can closely replicate the anterior cruciate ligament rupture in patients, which reliably initiates PTOA development. In other studies we utilize single-cell RNA sequencing to temporally explore differences in immune cell infiltration following injury. Although extreme care is taken during immune cell isolation to prevent contamination from bone marrow, we also wanted to rule out the possibility of contamination from bone marrow immune cells in our knee joint samples. Therefore, we proceeded to compare the neutrophil populations from uninjured joint (joint) to bone marrow (marrow) to identify the similarities and differences between these populations. Right knee joints and bone marrow obtained from Femur/Tibial bones of 10-week-old C57BL/6 mice were collected and immune (Cd45+) cells were analyzed using scRNA-seq.创伤后骨关节炎（Post-traumatic Osteoarthritis，PTOA）约半数发生于曾遭受关节损伤的个体，此类损伤涵盖胫骨平台骨折、半月板撕裂或前交叉韧带（anterior cruciate ligament，ACL）断裂。本研究采用可精准模拟患者前交叉韧带断裂的无创胫骨压迫损伤（noninvasive tibial compression injury，TCI）模型，该模型可稳定诱导创伤后骨关节炎的发生发展。在前期研究中，我们借助单细胞RNA测序（single-cell RNA sequencing，scRNA-seq）时序性探究损伤后免疫细胞浸润的差异变化。尽管在免疫细胞分离过程中已采取严格措施以避免骨髓污染，但我们仍希望排除膝关节样本中存在骨髓免疫细胞污染的可能性。为此，我们对未损伤关节与骨髓来源的中性粒细胞群开展对比分析，以明确二者之间的异同。本研究收集了10周龄C57BL/6小鼠的右膝关节及股骨/胫骨来源的骨髓样本，并通过单细胞RNA测序（scRNA-seq）对其中的CD45阳性（Cd45+）免疫细胞进行了分析。