蝾螈等动物具有断肢再生的能力，不过是什么保证了断腿的地方不会长出一条尾巴呢？英国《自然》杂志7月2日刊登的一项研究说，蝾螈的各种细胞具有记忆所属机体组织的能力，可良好地“专业分工”，帮助断肢再生。

《自然》杂志刊登的这项由德国和美国等国科学家进行的研究指出，研究人员利用基因技术向一种名为墨西哥钝口螈的蝾螈体内植入绿色荧光蛋白，再将相关细胞移植到有断肢的墨西哥钝口螈体内，这样就可以通过追踪荧光蛋白观察断肢再生的过程。

研究发现，蝾螈断肢创口周围的皮肤、肌肉、骨骼等各种细胞会聚集到一起，从成体细胞反向变为“幼年”细胞，形成具有再生能力的芽基细胞群。尽管这些芽基细胞看起来都差不多，但它们都记住了各自的来源，从肌肉细胞而来的仍再生为肌肉细胞，从神经鞘细胞而来的仍再生为神经鞘细胞。

更令人惊奇的是，从蝾螈肢体末端取下的软骨细胞，在移植到上臂部位后，居然慢慢移到了与其原有位置相对应的地方，证明这种细胞具有记忆位置的功能。

医学界一直在研究蝾螈、壁虎等动物的断肢再生能力，以发现帮助人类断肢再生的途径。研究人员认为，本次发现对于再生类药物的研发具有重要意义。

推荐原始出处：

Nature 460, 60-65 (2 July 2009) | doi:10.1038/nature08152

Cells keep a memory of their tissue origin during axolotl limb regeneration

Martin Kragl1,3,5,6, Dunja Knapp1,3,5, Eugen Nacu1,3, Shahryar Khattak1,3, Malcolm Maden4, Hans Henning Epperlein2 & Elly M. Tanaka1,3

1 Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108,
2 Institute of Anatomy, Medical Faculty, University of Technology Dresden, Fetscherstrasse 74,
3 Center for Regenerative Therapies, University of Technology Dresden, Tatzberg 47/49, 01307 Dresden, Germany
4 The Regeneration Project, McKnight Brian Institute, University of Florida, Rm 326 Bartram Hall, Gainesville, Florida 32611, USA
5 These authors contributed equally to this work.
6 Present address: Institute of Metabolic Physiology, Heinrich-Heine-Universit?t Düsseldorf, Universit?tsstrasse 1, 40225 Düsseldorf, Germany.

During limb regeneration adult tissue is converted into a zone of undifferentiated progenitors called the blastema that reforms the diverse tissues of the limb. Previous experiments have led to wide acceptance that limb tissues dedifferentiate to form pluripotent cells. Here we have reexamined this question using an integrated GFP transgene to track the major limb tissues during limb regeneration in the salamander Ambystoma mexicanum (the axolotl). Surprisingly, we find that each tissue produces progenitor cells with restricted potential. Therefore, the blastema is a heterogeneous collection of restricted progenitor cells. On the basis of these findings, we further demonstrate that positional identity is a cell-type-specific property of blastema cells, in which cartilage-derived blastema cells harbour positional identity but Schwann-derived cells do not. Our results show that the complex phenomenon of limb regeneration can be achieved without complete dedifferentiation to a pluripotent state, a conclusion with important implications for regenerative medicine.