细胞死亡可以用组织学方法，但需要把组织拿出来，这在许多情况下很难实现，例如干细胞移植后这些细胞是否仍存活的判断，最近一项新技术提供了一种无创伤的检测细胞死亡方法。

本周在《自然材料》网络版上报告了一种活体检测细胞死亡的技术，是以水凝胶为基础的纳米材料，然后利用MRI检测技术，可以活体无创伤地检测出那些细胞发生死亡。这不仅进一步加强了我们对活体细胞死亡过程的理解，更重要的是，利用这种技术可以帮助我们知道细胞移植到一个活体后细胞发生死亡的时间和地点。

流行的方法评价移植细胞的命运依赖于细胞标记方法，例如对某些和细胞有关的信号分子、受体或报告基因进行检测，但这些方法由于需要引入外源基因等缺点，临床应用受到很大限制。

迈克尔•麦克马洪和他的同事们报告的利用磁共振成像（MRI）检测pH值效应分子，采用非侵入性手段来检测细胞死亡。利用脂质体将pH-敏感的造影剂进行包装，由于细胞死亡伴随局部的pH值变化，使用MRI可以检测中这种改变，此方法对那些无法采用光学成像技术的深层组织尤其重要，而且获得的信息结合高分辨率MRI解剖图像，可以给临床评价带来重要信息。

Monitoring cell deathAdd to my bookmarksNature Materials

January 28, 2013

A hydrogel-based nanosensor reported online in Nature Materials this week furthers our understanding of the process, and most importantly the timing, of cell death following the transplantation of cells into a living organism.

Current methods to evaluate the fate of transplanted cells rely on either cell-labelling approaches, which may continue to give a signal following cell death, or the use of reporter genes, which has the clinical disadvantage of introducing foreign genetic material.

Now, Michael McMahon and colleagues report a pH-based sensor that, using magnetic resonance imaging (MRI), can non-invasively monitor cell death in vivo. By incorporating a pH-sensitive contrast agent into a liposomal microcapsule, changes in the local pH that accompany cell death are detected using MRI. This method allows the monitoring of cell death without the concerns of optical imaging techniques, for example, limited signal penetration of biological tissue. Furthermore, the information obtained can be combined with high-resolution anatomical images to allow easier clinical evaluation.