Institute for Regenerative Medicine, University of Zurich, 8952 Schlieren, Switzerland.
Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland.
Brain. 2023 Mar 1;146(3):823-841. doi: 10.1093/brain/awac393.
Stem cell therapy has been shown to improve stroke outcomes in animal models and is currently advancing towards clinical practice. However, uncertainty remains regarding the optimal route for cell delivery to the injured brain. Local intracerebral injections are effective in precisely delivering cells into the stroke cavity but carry the risk of damaging adjacent healthy tissue. Systemic endovascular injections, meanwhile, are minimally invasive, but most injected cells do not cross CNS barriers and become mechanically trapped in peripheral organs. Although the blood-brain barrier and the blood-CSF barrier tightly limit the entrance of cells and molecules into the brain parenchyma, immune cells can cross these barriers especially under pathological conditions, such as stroke. Deciphering the cell surface signature and the molecular mechanisms underlying this pathophysiological process holds promise for improving the targeted delivery of systemic injected cells to the injured brain. In this review, we describe experimental approaches that have already been developed in which (i) cells are either engineered to express cell surface proteins mimicking infiltrating immune cells; or (ii) cell grafts are preconditioned with hypoxia or incubated with pharmacological agents or cytokines. Modified cell grafts can be complemented with strategies to temporarily increase the permeability of the blood-brain barrier. Although these approaches could significantly enhance homing of stem cells into the injured brain, cell entrapment in off-target organs remains a non-negligible risk. Recent developments in safety-switch systems, which enable the precise elimination of transplanted cells on the administration of a drug, represent a promising strategy for selectively removing stem cells stuck in untargeted organs. In sum, the techniques described in this review hold great potential to substantially improve efficacy and safety of future cell therapies in stroke and may be relevant to other brain diseases.
干细胞治疗已被证明可以改善动物模型中的中风预后,目前正在向临床实践推进。然而,对于将细胞递送到受损大脑的最佳途径仍存在不确定性。局部脑内注射在精确地将细胞递送到中风腔中是有效的,但存在损伤相邻健康组织的风险。同时,系统血管内注射微创,但大多数注射的细胞不能穿过中枢神经系统屏障,并在周围器官中机械性滞留。尽管血脑屏障和血脑脊液屏障严格限制了细胞和分子进入脑实质,但免疫细胞可以穿过这些屏障,特别是在病理条件下,如中风。解析细胞表面特征和分子机制,为改善系统性注射细胞靶向递送到受损大脑提供了希望。在这篇综述中,我们描述了已经开发的实验方法,其中(i)细胞被工程化表达模仿浸润免疫细胞的细胞表面蛋白;或(ii)细胞移植物用缺氧或与药理学制剂或细胞因子孵育预处理。修饰后的细胞移植物可以与增加血脑屏障通透性的策略相结合。虽然这些方法可以显著增强干细胞向受损大脑的归巢,但细胞在非靶器官中的滞留仍然是一个不可忽视的风险。安全开关系统的最新发展,允许在给予药物时精确消除移植细胞,代表了一种有前途的策略,用于选择性地去除滞留于非靶向器官中的干细胞。总之,本综述中描述的技术有很大潜力,可以大大提高中风和其他脑部疾病未来细胞治疗的疗效和安全性。
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