Single cell RNA-sequencing of the human synovium in inflammatory arthritis
The study presents:  - an optimized synovium dissociation protocol for single cell RNA-sequencing studies of the human synovium. The protocol enables the isolation of high yield of viable synovial cells from prospectively collected fresh synovial biopsies from patients with inflammatory arthritis with a minimal sample droupout. The protocol is derived from the method for dissociation of cryopreserved synovia published by Donlin and colleagues (Arthritis Res. Ther. 2019).  - a reference single-cell atlas of fresh human synovium in inflammatory arthritis, comprising more than 100´000 unsorted synovial scRNA-seq profiles from 27 freshly dissociated synovia of patients with different types of inflammatory arthritis. The synovial cells segregate into ten lymphoid, 14 myeloid and 17 stromal synovial cell populations and subpopulations, including synovial neutrophils, representing broadly representing the cellular heterogeneity and composition of the human synovium in inflammatory arthritis.