Expression analysis of nail matrix in mouse

Mammalian digit-tip can regenerate upon amputation, like amphibians. It is unknown why this capacity is limited to the area associated with the nail. Here, we show that nail stem cells (NSCs) reside in the Wnt-suppressed proximal nail matrix and that the mechanisms governing NSC differentiation are directly coupled with their ability of orchestrating digit regeneration. Early nail progenitors located distal to the NCS region undergo Wnt-dependent differentiation into nail. Upon amputation, this Wnt activation is required for nail regeneration and also for attracting nerves that promote mesenchymal blastema growth, leading to regeneration of the entire digit. Amputations proximal to the Wnt-active nail progenitors result in failure to regenerate nail/digit. Nevertheless, beta-catenin stabilization in the NSC region induced their regeneration. These results establish a link between NCS differentiation and digit regeneration, suggesting a utility of the NSCs in developing novel treatments for amputees. Nail matrix cells were harvested from proximal and distal matrix region by microdissection and processed to RNA extraction and hybridization on Affymetrix microarrays. We analyzed two proximal and two distal matrix cells.与两栖动物类似，哺乳动物的指尖在截肢后具备再生能力。目前尚不明确为何该再生能力仅局限于与指甲相关的区域。本研究证实，指甲干细胞（nail stem cells，NSCs）存在于受Wnt信号抑制的近端指甲基质中，且调控NSCs分化的分子机制与其协调指尖再生的能力直接相关。位于NSC区域远端的早期指甲祖细胞会通过依赖Wnt信号的分化途径分化为指甲组织。截肢后，该Wnt信号激活不仅是指甲再生所必需的，同时也能招募促进间充质芽基生长的神经，最终实现整个指尖的完整再生。若在Wnt信号激活的指甲祖细胞近端实施截肢手术，则无法实现指甲或指尖的再生。不过，在NSC区域稳定β-连环蛋白可诱导其再生能力。上述研究结果证实了NSCs分化与指尖再生之间的关联，提示NSCs可用于开发针对截肢患者的新型治疗方案。研究人员通过显微解剖术从近端和远端指甲基质区域分离得到指甲基质细胞，并对其进行RNA提取，随后在Affymetrix基因芯片上完成杂交实验。本研究共分析了两份近端指甲基质细胞样本与两份远端指甲基质细胞样本。