I am currently working with single-cell RNA-seq data generated using the Parse Biosciences WT Mega Kit. We also have data generated using 10x Genomics from similar types of samples, allowing us to compare the two technologies.
I am observing a substantial difference in the clustering and cell-type separation between the two datasets.
In the 10x dataset, the different cell populations are relatively well separated in UMAP space. Moreover, when I examine the top differentially expressed genes (DEGs) for each cluster, they include well-known, cell-type-specific marker genes, which makes cell-type annotation relatively straightforward.
In contrast, in the Parse dataset, the clusters are much less distinct. Most of the clusters appear to be grouped together and form more of a continuous structure rather than clearly separated populations (I have attached an example UMAP for reference). More importantly, when I examine the top five DEGs for the clusters, they do not show the expected cell-type specificity, making cell-type annotation considerably more difficult.
I would therefore like to understand whether this could be related to the characteristics of Parse Biosciences data or whether there are specific preprocessing, normalization, feature-selection, dimensionality-reduction, or clustering steps that need to be adjusted for Parse data.
Has anyone experienced similar difficulties with cell-type separation or marker-gene identification when analysing Parse Biosciences scRNA-seq data?
Any advice or experience with this issue would be greatly appreciated.
Thanks in advance.
Best regards,
Nitin N.
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is the depth and number of detected genes comparable? First thing I would do is to use SingleR and use it to transfer the labels from 10x to the Parse dataset. Clustering is only one way to identify celltypes. Automated transfers like SingleR are often helpful.
Thank you for your response.
The number of detected genes and the sequencing saturation are comparable. Additionally, I plotted the expression of cell-type-specific markers in the Parse data, and I can see that the markers are expressed in specific clusters. However, these clusters are not clearly separated from each other.
I am attaching some examples of the marker expression for your reference.
Thanks and regards,
Nitin N.
Endothelial Marker:
Fibroblasts Marker:
Myeloid Cells Marker:
Hard to say just based on this image. I usually set UMAP parameters to enforce a certain spread (in the
uwot::umap()R versionspread = .5, min_dist = .5). Maybe it's just the settings here. Can you show how you run UMAP? Side note as a hematology dude, CD74 is a MHCII-associated gene, so it marks APCs, not myeloid cells (B cells and pDCs will have just), just use CD45 (Ptprc) to see leukocytes.