Single Cell Transcriptome Conservation in Cryopreserved Cells and Tissues
Ontology highlight
ABSTRACT: Sample preservation method that maintains transcripts in viable single cells and so allows to disconnect time and place of sampling from subsequent processing steps.
Project description:The use of single-cell technologies for clinical applications requires disconnecting sampling from downstream processing steps. Early sample preservation can further increase robustness and reproducibility by avoiding artifacts introduced during specimen handling. We present FixNCut, a methodology for the reversible fixation of tissue followed by dissociation that overcomes current limitations. We applied FixNCut to human and mouse tissues to demonstrate the preservation of RNA integrity, sequencing library complexity, and cellular composition, while diminishing stress-related artifacts. Besides single-cell RNA sequencing, FixNCut is compatible with multiple single-cell and spatial technologies, making it a versatile tool for robust and flexible study designs.
Project description:Archaeological bone material is increasingly being sampled for various molecular analyses. Minimally invasive sampling protocols should therefore be utilised whenever possible. We compare the proteomic output of 10 Early Neolithic Bos sp. humeri, from two different preservation contexts, of seven sampling protocols, namely retrieving bone chips (with and without demineralisation), acid etching (FASP and chemical neutralisation), eraser, membrane box, and polishing film. We note that minimally invasive sampling methods can extract a substantial amount of protein groups and provide sufficient taxonomic identifications if preservation conditions are favorable. However, if preservation conditions are poorer more invasive sampling techniques should be considered.
Project description:Background Insulinoma is the most common pancreatic neuroendocrine tumour in dogs and humans. The understanding of driving factors and critical survival genes in insulinomas is limited and overall survival is poor for canine and human malignant insulinoma. This study aimed to use single-cell RNA-sequencing to conduct a multispecies analysis of insulinoma cell lines to understand their single-cell transcriptomic landscape. Secondly, the impact of freeze-thawing on the pancreatic beta single-cell transcriptome was investigated, to determine whether cryoarchiving of primary insulinoma samples may be feasible in future studies. Methods Single-cell transcriptomic analysis was performed using fresh and cryopreserved multispecies insulinoma cell lines (canINS, CM, INS-1 and MIN6). R and Seurat were used to perform cell clustering and specific cluster marker genes were identified by the FindMarkers function. Metascape was used to identify statistically enriched pathways for specific cell clusters. Differentially expressed genes between fresh and cryopreserved single-cell transcriptome profiles, were defined as genes with a log2 fold change >0.25 and a Bonferroni-adjusted P<0.05, based on the Wilcoxon rank sum test. Results Based on the specific cell line single-cell transcriptome profiles, five or six cell clusters were constructed per cell line. All cell lines expressed neuroendocrine markers and additionally INS-1 and MIN6 displayed a gene signature indicative of mature/functional pancreatic islet/beta-cells. DEPTOR, BICC1, GHR, CCNB2, CENPA, LMO4, VANGL1, and L1CAM were identified as cross-species conserved insulinoma cluster marker genes. Little effect was found of cryopreservation and thawing on overall gene expression at the single-cell level in insulinoma cell lines: only 6 and 29 genes had a log2 fold change > 1 in cryopreserved versus fresh canINS and CM, respectively. Conclusions canINS, CM, INS-1 and MIN6 are all principally relevant as insulinoma models and the demonstrated differences in their single-cell transcriptomic profiles could aid researchers in selecting the appropriate cell lines for specific study objectives. Cross-species conserved insulinoma cluster marker genes were identified that harbour oncogenes and their involvement in insulinoma tumourigenesis should be investigated in future studies. The good comparability between cryopreserved and fresh insulinoma cells allows for inclusion of cryopreserved insulinoma patient samples in future studies, which allows for reduced assay-based variability.
Project description:Ballan wrasse (Labrus bergylta) is used as a cleaner fish in Norwegian aquaculture to control sea lice. Thus, knowledge on the digestive physiology and nutrient requirements, as well as the ontogeny of the immune system is important. In this study, two different diets were tested; diet 1 was used as control diet consisting of artemia and rotifers cultivated and enriched in the in-house facility at IMR, Austevoll, Bergen (Norway). Diet 2 consists in plankton which has successfully been used before in cod larvae generating more robust individuals. Sampling was done according to the standard length of the larvae rather than age (dph). Sampling point 0 (BW0) (4 mm), sampling point 2 (BW2) (4,5 mm), sampling point 3 (BW3) (5,7 to 6 mm), sampling 4 (BW4) (7 to 7,5 mm), sampling point 5 (BW5) (10 to 10,5 mm), sampling point 6 (BW6) (16 to 16,5 mm), and sampling point 7 (BW7) (25 to 30 mm). Ontogeny of lymphoid organs and mucosal associated lymphoid tissues in ballan wrasse and the effect of different diets were investigated.