Evaluation and further development of small molecule probes to study the role of prion protein in the ageing and renewal of stem cells

干细胞是一种特殊类型的细胞，具有自我再生（自我更新）的独特能力，并能发育成能够在体内执行特殊任务的其他细胞类型。因此，干细胞有潜力通过用于修复特定组织或作为再生或修复药物生长器官来改变疾病治疗的面貌。然而，干细胞研究一直处于争论的中心，因为目前大多数研究涉及胚胎干细胞的使用。研究中使用的胚胎干细胞来自早期人类胚胎。为了培育干细胞系，通常需要破坏人类胚胎。这引起了巨大的伦理问题，必须对这一领域的工作进行严格监管。虽然这些细胞很容易在实验室中生长；技术障碍，如胚胎的可用性、从胚胎干细胞中产生用于医疗用途的特定类型组织和器官的方法，以及由于它们来自不同的供体而被受体排斥的可能性，使研究进一步复杂化。替代胚胎干细胞的一种方法是使用成体干细胞。它们可以在身体的不同组织中找到，进行自我更新，并可以发育成其他类型的细胞。它们的优点是可以从患者自身的组织中获得，因此避免了伦理问题和免疫系统排斥的问题。某些类型的成体干细胞，如造血干细胞（HS），已经被常规用于骨髓移植。然而，它们的数量非常少，而且这个数量随着捐赠者的年龄而减少。此外，在实验室中分离和培养大多数成体干细胞的尝试都失败了，因为它们衰老得很快，在生活环境之外就失去了发育成不同组织的能力。因此，在这一领域工作的科学家面临的主要技术挑战在于将它们与许多其他细胞分离开来，能够使它们在不老化的情况下生长和繁殖，并在实验室中保持它们的发育能力。一旦这些问题被克服，成体干细胞在再生医学中的应用将迅速起飞。最近的研究表明，朊蛋白也大量存在于干细胞表面，这种蛋白与致命的神经退行性疾病家族（称为传染性海绵状脑病（tse））或朊蛋白疾病（如山羊和绵羊的痒病、牛的疯牛病和人类的vCJD）有关。研究表明，在HS细胞中，它们有助于这些细胞的更新。本提案旨在解决干细胞研究中的衰老和更新问题。这将通过使用优化的小分子结合物探测胚胎癌（EC）、胚胎干（ES）细胞和成体间充质干细胞（MS）细胞表面的细胞朊病毒蛋白（PrPC）的功能来实现。EC细胞将用于初始高通量筛选，以观察在申请人组中发现的224种粘合剂对干细胞生长的一般影响，然后使用ES细胞进行确认。活性结合物将被进一步优化，以产生一些高亲和力的结合物，选定的结合物将被研究其在多发性硬化症细胞中的老化和更新，这些细胞可能分化成骨骼和软骨，用作再生药物。

Stem cells are particular types of cells that have unique power in regenerating themselves (self-renewal) and developing into other cell types capable of carrying out special tasks in the body. Therefore, stem cells have the potential to change the face of disease treatment by being used to repair specific tissues or to grow organs as regenerative or reparative medicine. However, stem cell research has been at the center of debate for because the majority of current research involves the use of embryonic stem cells. Embryonic stem (ES) cells used in the research are from early stage human embryos. The destruction of a human embryo is usually required in order to start a stem cell 'line'. This poses great ethical concerns and the work in this field has to be vigorously regulated. Although these cells are easy to grow in the laboratory; technical hurdles such as the availability of embryos, methods for producing particular types of tissues and organs from ES cells for intended medical use and the possibility of their rejection by the recipient because they are from different donors, further complicate the research. An alternative to ES cells is the use of adult stem cells. They can be found in the different tissues of the body, undergo self-renewal and can develop into other cell types. They have an advantage that they can be obtained from the patient's own tissue, therefore avoiding the ethical issues and problem of rejection by the immune system. Some type of adult stem cells such as haemopoietic stem (HS) cells, are already being used routinely in bone marrow transplantations. However they exist in very small numbers and this number decreases with the age of the donor. In addition, attempts to isolate and grow most adult stem cells in the laboratory have failed because they age rapidly and the ability of developing into different tissues is lost outside living environments. Therefore the main technical challenges for scientists working in this field lie in isolating them from many other cells, being able to keep them growing and reproducing without aging and maintaining their ability of development in the laboratory. The use of adult stem cells in regenerative medicine can take off rapidly once these problems are overcome. Recent studies have shown that prion proteins, which are connected with a family of deadly neurodegenerative diseases called transmissible spongiform encephalopathies (TSEs) or prion diseases (such as scrapie in goats and sheep, mad cow disease in cattle and vCJD in human) are also present in abundance on the surface of stem cells. It has been shown that in HS cells they help the renewal of these cells. This proposal aims to tackle the problem of aging and renewal in stem cell research. This will be achieved by probing the function of cellular prion protein (PrPC) on the surface of embryonal carcinoma(EC), embryonic stem (ES) cells, and adult mesenchymal stem (MS) cells, using optimised small molecule binders. EC cells will be used in initial high throughput screening to see the effects of 224 binders discovered in the applicants' group on the growth of the stem cells in general, followed by confirmation using ES cells. The active binders will then be further optimised to give rise to some high affinity binders and selected binders will be studied for their ageing and renewal in MS cells, which can potentially differentiate into bones and cartilage to be used as regenerative medicines.