A structured evaluation of cryopreservation in generating single cell transcriptomic from cerebrospinal fluid

Recent advances in single-cell transcriptomics now allow characterization of CSF cells at an unprecedented scale and precision. With the availability of different single cell technologies with which to characterize CSF cells, there is a need for a simple yet robust protocol to cryopreserve CSF cells. In this study, we report a reliable cryopreservation protocol adapted for CSF cells that facilitates the characterization of these rare, fragile cells in moderate to large scale studies. To establish this protocol, excess CSF was collected following diagnostic lumbar punctures in twenty-one patients at two independent sites, and CSF cells were isolated. Each cell sample was split into two fractions for single cell analysis using one of two possible chemistries: 3' sc-RNA-Sequencing or 5'sc-RNA-Sequencing. One cell fraction was processed fresh while the second sample was cryopreserved and profiled at a later time after thawing. B and T cell receptor sequencing were performed in a subset of samples. Our comparison of fresh and cryopreserved data from the same individuals demonstrates highly efficient recovery of all known CSF cell types. The proportion of all cell types was similar between the fresh and the cryopreserved cells processed, and cellular transcriptomes were not significantly different. Results were comparable at both performance sites and with different single cell sequencing chemistries. Cryopreservation also did not affect recovery of T and B cell clonotype diversity. Hence, our cryopreservation protocol for CSF cells provides an important alternative to fresh processing of fragile CSF cells which is also resource-intensive: cryopreservation enables the involvement of research sites with limited capacity for experimental manipulation and reduces technical variation by enabling batch processing and pooling of samples. sequencing (scRNA-seq) to analyze the diversity of GCs in the intestine. Overall design: Using sc-RNA-Seq we analyzed 44 individual CSF-cell samples from a total of 21 patients affected by other neuroimmunological diseases, migraine and others. Each sample was split into two fractions, one fresh and one fraction was cryopreserved and further thawed prior analysis, except for two CSF samples that were split into 3 fractions (2 fresh and 1 cryopreserved).