Platelet-derived growth factor receptor signaling is required for postnatal tendon growth

Platelet-derived growth factor receptor (PDGFR) signaling plays an important role in the embryonic formation of many different tissues. There is a family of PDGF isoforms which signal through the PDGF receptors α (PDGFRα) and β (PDGFRβ). PDGF regulates many key cellular processes of mesenchymal cell function including proliferation, differentiation, migration and extracellular matrix (ECM) synthesis. While PDGF has been used to enhance flexor tendon healing in vivo, its role in postnatal tendon growth has remained largely unexplored. To determine the importance of PDGFR signaling in postnatal tendon growth, we performed pharmacological blockade of PDGFRα and PDGFRβ, and then induced tendon growth via mechanical overload using the hindlimb synergist ablation model. Our hypothesis was that inhibition of PDGFR signaling will restrict normal growth of tendon tissue in response to mechanical loading. 10 pooled samples total. Equal amounts of RNA isolated from four individual tendons were pooled into a single sample for microarray analysis, and two pooled samples from each group were analyzed. RNA was pooled because gene expression from a pooled sample is similar to the average of the individual samples composing the pooled sample.

血小板衍生生长因子受体（platelet-derived growth factor receptor, PDGFR）信号通路在多种组织的胚胎形成过程中发挥重要作用。目前已发现一类血小板衍生生长因子（PDGF）亚型家族，其通过血小板衍生生长因子受体α（PDGFRα）与β（PDGFRβ）介导信号转导。PDGF可调控间充质细胞功能的多项核心细胞进程，包括增殖、分化、迁移以及细胞外基质（extracellular matrix, ECM）合成。尽管PDGF已被用于体内（in vivo）增强屈肌腱愈合，但其在产后肌腱生长中的作用仍未得到广泛探究。为明确PDGFR信号通路在产后肌腱生长中的重要性，我们采用药理学手段阻断PDGFRα与PDGFRβ，随后通过后肢拮抗肌切除模型施加机械超负荷以诱导肌腱生长。本研究的假说为：抑制PDGFR信号通路将限制肌腱组织在机械负荷刺激下的正常生长。本研究共纳入10个混合样本：将4根独立肌腱分离得到的等量RNA混合为单个样本以进行基因芯片分析（microarray analysis），每组设置2个混合样本用于检测。采用混合样本的原因在于，混合样本的基因表达水平与组成该混合样本的独立样本的平均表达水平相近。