毛囊形成是真皮和表皮细胞信号交换、干细胞有序分化的结果。毛乳头（DP）细胞具有毛囊诱导功能，临床研究应用其低代数培养液即可诱导毛发再生，而高代数DP细胞则失去该功能，但机制未明。我们前期应用iTRAQ定量蛋白质谱分析发现，与干细胞趋化密切相关的SDF-1(间质细胞趋化因子）在低/高代数DP细胞培养液中差异明显，进一步把SDF-1重组蛋白注射到裸鼠皮下时，能成功诱导毛发生长，同时检测到Wnt信号通路被激活。由此，我们提出科学假说：“DP细胞分泌的SDF-1启动干细胞定向迁移，介导其通路下游因子激活Wnt通路，从而诱导干细胞有序分化，形成毛囊结构”。项目拟在毛囊诱导模型和干细胞共培养体系中揭示SDF-1是DP细胞诱导毛囊形成的关键因子，再结合基因沉默、过表达等技术证实上述假说。这将为DP细胞诱导毛囊再生奠定重要分子基础，也为利用DP细胞分泌的关键因子开发毛发再生药物提供新靶点。

It is well known that hair follicle (HF) formation is the result of intercellular signaling between dermal and epidermal cells, as well as the well-organized differentiation of stem cells (SCs). HF regeneration can be induced by factors secreted by dermal papilla cells (DPCs), as judged by the ability of DPC-conditioned culture medium (CM) to induce HF regeneration. However, late-passage DPCs lose this function due to unknown mechanisms. Using iTRAQ-based quantitative proteomic technology, we found that stromal cell-derived factor 1 (SDF-1) was differentially expressed between early- and late-passage DPC-CM. Subcutaneous injection of SDF-1 into nude mice activated the HF regeneration-related Wnt signal pathway and induced HF regeneration. These results suggest that DPC-secreted SDF-1 alone is sufficient for initiation of directed stem cell migration and activation of the Wnt signaling pathway to induce the differentiation of SCs into HFs. We aim to prove that SDF-1 is the key factor, in DPC-CM, that induces HF regeneration by using an HF induction model and SC co-culture system. Gene silencing and over-expression will be further used to confirm our hypothesis. This study will identify the molecular mechanism of DPC-mediated HF induction and provide new therapeutic targets for hair regeneration using key factors secreted by DPCs.