英国剑桥大学的研究人员近日通过移植瘫痪宠物狗的鼻子的内壁细胞，成功使其自身再次站起并行走。对于这项新技术，剑桥大学的研究小组持谨慎乐观的态度，认为它或许最终可以用于治疗瘫痪患者。
这是研究人员首次使用真正的受伤宠物，而非实验动物进行细胞移植的实验。实验动物指的是经人工繁育，用于科学研究、教学、生产、检定以及其他科学实验的动物。而此次使用的宠物狗由于脊髓受损，后腿都曾无法站立。
在实验中，研究者们首先提取出宠物狗鼻腔内壁的嗅鞘细胞，培养数周后这些细胞会有所生长和扩大。然后，研究人员再把这些经过培养的细胞注射到23只瘫痪狗的受损脊髓内。结果显示，大部分接受细胞移植的狗狗的病情明显好转，它们可以在安全带的帮助下，在跑步机上行走。不过，目前还没有一只狗的后腿完全恢复奔跑能力。
在参与实验的宠物狗中，有一只名叫贾斯珀的达克斯猎狗。它的主人梅·海伊表示：“在接受治疗前，贾斯珀的后腿根本不能动弹，我们通常要用手推车推着它出去散步。但现在，它能在屋子里和花园里到处乱窜，还能和其他狗狗一起玩耍。这真是太好了。”
此次实验得到英国医学研究委员会的资助，由该委员会的再生医学中心和剑桥大学兽医学院合作完成，其成果已发表在国际神经科学一流杂志《脑》上。
参与研究的生物学家罗宾·富兰克林教授说：“我们的发现令人异常兴奋，它第一次表明将此类细胞移植到受损严重的脊髓内后，可以大大改善患者的病情……我们相信这项技术至少能够恢复脊髓受损的人类患者的部分活动能力，但在治愈这种病症方面，我们还有很长的路要走。”
富兰克林指出，移植的嗅鞘细胞可以使受损脊髓内的神经纤维再次生长，进而使瘫痪狗的后腿能够再次活动，并与前肢相互配合。不过，如果大脑与受损脊髓之间距离过长，新生的神经纤维将无法实现其连接功能。
对此，英国医学研究委员会的科学家们表示，对于那些因脊髓受损而丧失性功能和大小便失控的患者而言，这是个非常关键的问题。
英国伦敦大学学院神经再生系主任杰弗里·雷斯曼教授也指出：“目前还无法治愈脊髓受伤的人类病患，我们距离这个标准还有很长的一段距离。不过，上述研究成果是近几年来最振奋人心的发现，是朝这个方面迈出的一大步。”
Myelin is dependent on the Charcot–Marie–Tooth Type 4H disease culprit protein FRABIN/FGD4 in Schwann cells
Michael Horn, Reto Baumann, Jorge A. Pereira, Páris N. M. Sidiropoulos, Christian Somandin, Hans Welzl, Claudia Stendel, Tessa Lühmann, Carsten Wessig, Klaus V. Toyka, João B. Relvas, Jan Senderek and Ueli Suter
Studying the function and malfunction of genes and proteins associated with inherited forms of peripheral neuropathies has provided multiple clues to our understanding of myelinated nerves in health and disease. Here, we have generated a mouse model for the peripheral neuropathy Charcot–Marie–Tooth disease type 4H by constitutively disrupting the mouse orthologue of the suspected culprit gene FGD4 that encodes the small RhoGTPase Cdc42-guanine nucleotide exchange factor Frabin. Lack of Frabin/Fgd4 causes dysmyelination in mice in early peripheral nerve development, followed by profound myelin abnormalities and demyelination at later stages. At the age of 60 weeks, this was accompanied by electrophysiological deficits. By crossing mice carrying alleles of Frabin/Fgd4 flanked by loxP sequences with animals expressing Cre recombinase in a cell type-specific manner, we show that Schwann cell-autonomous Frabin/Fgd4 function is essential for proper myelination without detectable primary contributions from neurons. Deletion of Frabin/Fgd4 in Schwann cells of fully myelinated nerve fibres revealed that this protein is not only required for correct nerve development but also for accurate myelin maintenance. Moreover, we established that correct activation of Cdc42 is dependent on Frabin/Fgd4 function in healthy peripheral nerves. Genetic disruption of Cdc42 in Schwann cells of adult myelinated nerves resulted in myelin alterations similar to those observed in Frabin/Fgd4-deficient mice, indicating that Cdc42 and the Frabin/Fgd4–Cdc42 axis are critical for myelin homeostasis. In line with known regulatory roles of Cdc42, we found that Frabin/Fgd4 regulates Schwann cell endocytosis, a process that is increasingly recognized as a relevant mechanism in peripheral nerve pathophysiology. Taken together, our results indicate that regulation of Cdc42 by Frabin/Fgd4 in Schwann cells is critical for the structure and function of the peripheral nervous system. In particular, this regulatory link is continuously required in adult fully myelinated nerve fibres. Thus, mechanisms regulated by Frabin/Fgd4–Cdc42 are promising targets that can help to identify additional regulators of myelin development and homeostasis, which may crucially contribute also to malfunctions in different types of peripheral neuropathies.
