Cryopreservation of stem cells

干细胞是一种特殊类型的细胞，它可以自我更新，并且可以生长成许多其他类型的细胞。科学家们不仅在胚胎（所谓的胚胎干细胞）中发现了干细胞，而且在成人（成体干细胞，例如来自骨髓的干细胞）中也发现了干细胞。干细胞对于组织/器官修复（如大脑、心脏和其他组织）可能非常有用。但是为了将基于干细胞的疗法应用到临床环境中，必须克服许多技术障碍。其中之一就是如何长期保存干细胞。最可行的方法是冷冻保存。例如，当婴儿出生时，脐带血中的干细胞可以被收集、分离、冷冻并储存在液氮温度（-196℃）下。如果在他（或她）生命的后期需要干细胞，他（或她）的细胞可以解冻，（适当的）治疗可以开始。其他类型的干细胞也可以类似地保存下来。问题是干细胞不喜欢低温（这并不奇怪）。他们可能只是死亡，或者失去一些重要的功能。额外的复杂性是，不容易判断丢失了哪些/有多少函数。该项目主要关注两个重要问题：(1)如何通过使用更好的冷冻保存剂（例如使用防冻蛋白保护北极鱼类）来确保干细胞功能的保存，从而调整我们冷冻细胞的速度；(2)如何通过使用新型显微镜来三维观察细胞内部和周围的任何损伤。在项目结束时，我们希望我们将有最佳的冷冻保护化学配方和光学协议，可用于干细胞库，研究实验室，医院和工业。

Stem cells are special type of cells which can renew themselves, and can grow into many other cell types. Scientists have found stem cells not only in embryo (so called embryonic stem cells) but also in adults (adult stem cells, e.g from bone marrow). Stem cells could be very useful for tissue/organ repair (e.g brain, heart and other tissue). But in order to apply stem cell based therapies into clinic settings, many technical obstacles must be overcome. One of these is how to preserve stem cells for long term. The most feasible method is cryopreservation. For example, when a baby is born, the stem cells in the cord blood can be collected, separated, frozen and stored at liquid nitrogen temperature (-196 oC). If in later stage in his (or her) life the individual needs stem cells, his (or her) cells can be thawed and (appropriate) therapy can be started. Other types of stem cells can similarly be preserved. The problem is that stem cells do not like low temperatures (not a surprise). They may simply die, or lose some important functions. The additional complexity is that it is not easy to tell what/how many functions are lost. This project focuses on two important questions (1) how to make sure stem cell functions be preserved by using better cryopreservation agents (e.g use of antfreeze proteins protecting fishes in arctic) and thereby adjusting how fast we freeze the cells, and (2) how to detect any damage by using new type of microscope to three dimensionally see inside and around the cells. At the end of the project, we hope we will have optimal cryoprotecting chemical formulation and optical protocols, which can be used by stem cell banks, research laboratories, hospitals and industry.