Visualising gene expression across cell type and conditions in one plot, in Single Cell Sequencing data
Try using SplitDotPlotGG, this will allow you to color the dots by some additional variable (eg condition).

In your case you would want to do something like this:

library(Seurat)

SplitDotPlotGG(object = object,
               genes.plot = c("Gene1", "Gene2"),
               plot.legend = TRUE,
               group.by = "cell_types",
               grouping.var = "tissue_types")


This would give a result similar to below (an example from https://satijalab.org/seurat/immune_alignment.html).