I am currently doing RNA Velocity Analysis using scRNA-seq data from human blood and skin. The RNA Velocity is calculated using the balance of spliced and unspliced mRNA. One thing my PI and me were just wondering about is, whether there is an expected or average amount of unspliced mRNA in human cell samples. For instance, the cells we've taken from blood apparently contain 25% unspliced mRNA and the cells taken from skin contain 30% unspliced mRNA. When only looking at T cells for each samples, the amount of unspliced mRNA is a bit lower.
Until now I couldn't find anything about what ratios are common and if there is any way to biologically interprete them. The only thing I found is, that 10%-20% of unspliced mRNA is relatively low for RNA Velocity estimation.
Is there an amount of unspliced mRNA where one could say, that it is unsually high or low? And how could one interprete the ratio from a biological point of view besides that it tells us something about the rate of transcription?