Summary of Glioma & scRNA-seq-1

杀杀

[1] Review

Dissecting human gliomas by single-cell RNA sequencing

PMID: 29016805

胶质瘤的瘤内异质性很大程度影响了治疗和复发，已经在2016年被修订的WHO胶质瘤分类指南中，已经讨论了早年一直存在的分型之一的“少支星型胶质瘤”，这种分型由于在组织学观察中显示了少支细胞和星型细胞的两种形态，并且两种形态的占比难以判定，因此被分类为一种混合型的实体。即便是被分类为“少支胶质细胞瘤”，或“星型胶质细胞瘤”，也不可避免地混合存在其它类型的细胞。这种情况导致了治疗的时候无法针对性地治疗某一种胶质瘤亚型。除此之外，胶质瘤中混有的干细胞/祖细胞也很难被靶向。这些都导致了治疗后朝更恶性的方向复发的潜在可能性。

大脑是一个较为复杂的器官，当然不止由胶质细胞构成，一个神经单元内包含了许多其它的细胞和物质，构成了大脑内的微环境，而血脑屏障隔离了大脑与人体血液循环，并通过血脑屏障特定的功能完成大脑和人体营养的交换。因此，胶质瘤的发生除了跟单个细胞的功能相关，还和大脑内其它细胞的互相作用相关。 PMID: 26590417

这篇综述对影响胶质瘤发生/进展的因素总结为：
(i) Genetic alterations drive cellular transformation and the evolution of cancer cells;
(ii) cellular lineages and their associated developmental pathways and epigenetic programs ascribe cancer cells with key phenotypic and functional features; programs such as those of neural stem/progenitor cells, oligodendrocyte progenitor cells, and mature glial cells (astrocytic, oligodendrocytic, ependymal) strongly influence cancer cell behavior;
(iii) diverse nonmalignant cells, including microglia, macrophages, lymphocytes, endothelial, and other cells—collectively forming the tumor microenvironment (TME)—further influence glioma biology and response to therapy.

因此，单细胞的研究十分必要，单细胞研究除了能够分析胶质瘤的瘤内异质性，研究肿瘤发生的时序，还能够对除了胶质瘤细胞外的其它细胞进行分析，阐明影响胶质瘤发生发展、复发的因素。

单细胞测序的一般流程：
Single-cell DNA or RNA profiling of tumors is conceptually similar to bulk profiling, with few important differences.
First, tumor samples are acutely disaggregated into single-cell suspension using a combination of mechanical and enzymatic digestion protocols.
Second, individual cells are separated either by flow cytometry into 96/384-well plates or by microfluidic devices into distinct chambers (eg, by Fluidigm C1) or droplets (eg, in Drop-Seq, In-Drop, or 10X platforms before they are profiled).