Seurat Integration Guide

Introduction

SCEVAN seamlessly integrates with Seurat, the most widely used R toolkit for single-cell analysis. This guide demonstrates how to:

Extract count matrices from Seurat objects
Add SCEVAN results back to Seurat
Visualize CNA information in Seurat plots

SCEVAN supports both Seurat v4 and v5 data structures.

Setup

library(SCEVAN)
library(Seurat)
library(ggplot2)
library(dplyr)

Extracting Data from Seurat

Using getCountMtxFromSeurat()

SCEVAN provides a helper function that works with both Seurat v4 and v5:

# Load your Seurat object
seurat_obj <- readRDS("path/to/seurat_object.rds")

# Extract raw counts (v4/v5 compatible)
count_mtx <- getCountMtxFromSeurat(
  seurat_obj,
  assay = "RNA",      # Default assay
  layer = "counts"    # For Seurat v5
)

# Check dimensions
dim(count_mtx)

Manual Extraction

For more control, you can extract manually:

# Seurat v4
count_mtx <- as.matrix(GetAssayData(seurat_obj, slot = "counts"))

# Seurat v5
count_mtx <- as.matrix(GetAssayData(seurat_obj, layer = "counts"))

Running SCEVAN

Standard Analysis

# Run SCEVAN pipeline
results <- pipelineCNA(
  count_mtx,
  sample = "MySample",
  par_cores = 4,
  organism = "human",
  SUBCLONES = TRUE
)

# View results
head(results)

Using Seurat Clusters as Prior

You can use Seurat’s clustering to identify potential normal cells:

# Get cluster assignments
clusters <- Idents(seurat_obj)

# Identify clusters with normal cell markers
# (e.g., immune clusters, fibroblast clusters)
normal_clusters <- c("T_cells", "Macrophages", "Fibroblasts")
potential_normals <- names(clusters)[clusters %in% normal_clusters]

# Run SCEVAN with known normals
results <- pipelineCNA(
  count_mtx,
  sample = "MySample_guided",
  norm_cell = potential_normals,
  SUBCLONES = TRUE
)

Adding Results to Seurat

Add Cell Classifications

# Ensure cell names match
results_matched <- results[colnames(seurat_obj), , drop = FALSE]

# Add all SCEVAN columns
seurat_obj <- AddMetaData(seurat_obj, metadata = results_matched)

# Check added columns
head(seurat_obj@meta.data)

Add CNA Scores

# Load CNA matrix
load("./output/MySample_CNAmtx.RData")
load("./output/MySample_count_mtx_annot.RData")

# Calculate global CNA score per cell
global_cna <- colMeans(abs(CNA_mtx_relat))
seurat_obj$CNA_score <- global_cna[colnames(seurat_obj)]

# Calculate chromosome-specific scores
chr7_cna <- colMeans(CNA_mtx_relat[count_mtx_annot$seqnames == 7, ])
seurat_obj$chr7_cna <- chr7_cna[colnames(seurat_obj)]

chr10_cna <- colMeans(CNA_mtx_relat[count_mtx_annot$seqnames == 10, ])
seurat_obj$chr10_cna <- chr10_cna[colnames(seurat_obj)]

Visualization in Seurat

UMAP with Cell Classification

# Color by malignant/normal classification
DimPlot(
  seurat_obj, 
  group.by = "class",
  cols = c("tumor" = "#E74C3C", "normal" = "#3498DB", "filtered" = "gray")
) +
  ggtitle("SCEVAN Cell Classification")

UMAP with Subclones

# Color by subclone (tumor cells only)
DimPlot(
  seurat_obj,
  group.by = "subclone",
  na.value = "lightgray"
) +
  ggtitle("Tumor Subclone Assignment")

Feature Plot with CNA Scores

# Global CNA burden
FeaturePlot(
  seurat_obj,
  features = "CNA_score",
  cols = c("lightgray", "red")
) +
  ggtitle("Global CNA Score")

# Chromosome-specific
FeaturePlot(
  seurat_obj,
  features = c("chr7_cna", "chr10_cna"),
  cols = c("blue", "white", "red"),
  min.cutoff = -0.3,
  max.cutoff = 0.3
)

Violin Plots

# CNA score by cell type
VlnPlot(
  seurat_obj,
  features = "CNA_score",
  group.by = "class",
  pt.size = 0
) +
  NoLegend()

# CNA by Seurat cluster
VlnPlot(
  seurat_obj,
  features = "CNA_score",
  group.by = "seurat_clusters",
  pt.size = 0
)

Advanced Integration

Region-Specific CNA Visualization

# Define genomic regions of interest
regions <- list(
  EGFR = c(chr = 7, start = 55019017, end = 55211628),
  CDKN2A = c(chr = 9, start = 21967751, end = 21995301),
  PTEN = c(chr = 10, start = 87863113, end = 87971930)
)

# Calculate CNA for each region
for(gene in names(regions)) {
  r <- regions[[gene]]
  region_cna <- colMeans(CNA_mtx_relat[
    count_mtx_annot$seqnames == r["chr"] &
    count_mtx_annot$start >= r["start"] &
    count_mtx_annot$end <= r["end"], , drop = FALSE
  ])
  seurat_obj[[paste0(gene, "_cna")]] <- region_cna[colnames(seurat_obj)]
}

# Visualize
FeaturePlot(seurat_obj, features = c("EGFR_cna", "PTEN_cna"))

Combined Visualization

# Create combined plot with classification and clustering
p1 <- DimPlot(seurat_obj, group.by = "class") + 
  ggtitle("SCEVAN Classification") + NoLegend()

p2 <- DimPlot(seurat_obj, group.by = "seurat_clusters") + 
  ggtitle("Seurat Clusters") + NoLegend()

p3 <- FeaturePlot(seurat_obj, features = "CNA_score") + 
  ggtitle("CNA Score")

p4 <- DimPlot(seurat_obj, group.by = "subclone", na.value = "lightgray") + 
  ggtitle("Subclones")

# Combine
(p1 | p2) / (p3 | p4)

Downstream Analysis

Differential Expression by Subclone

# Set identity to subclone
Idents(seurat_obj) <- "subclone"

# Find markers for each subclone
subclone_markers <- FindAllMarkers(
  seurat_obj,
  only.pos = TRUE,
  min.pct = 0.25,
  logfc.threshold = 0.25
)

# Top markers per subclone
top_markers <- subclone_markers %>%
  group_by(cluster) %>%
  top_n(10, avg_log2FC)

print(top_markers)

Pathway Analysis per Subclone

# Use marker genes for pathway analysis
# Example with enrichR or clusterProfiler

# Get genes from subclone 1
s1_genes <- subclone_markers %>%
  filter(cluster == 1, p_val_adj < 0.05) %>%
  pull(gene)

# Run enrichment (requires clusterProfiler)
# enrichGO(s1_genes, OrgDb = org.Hs.eg.db, keyType = "SYMBOL")

Creating New Seurat Object

From Scratch with SCEVAN Results

# Create new Seurat object with SCEVAN metadata
seurat_new <- CreateSeuratObject(
  counts = count_mtx,
  meta.data = results,
  project = "SCEVAN_analysis"
)

# Standard Seurat workflow
seurat_new <- NormalizeData(seurat_new)
seurat_new <- FindVariableFeatures(seurat_new)
seurat_new <- ScaleData(seurat_new)
seurat_new <- RunPCA(seurat_new)
seurat_new <- RunUMAP(seurat_new, dims = 1:30)

# Visualize with SCEVAN results
DimPlot(seurat_new, group.by = "class")

Best Practices

Memory Management

# For large datasets, process in chunks
# or use sparse matrices

# Check memory usage
format(object.size(seurat_obj), units = "GB")

# Remove intermediate objects
rm(CNA_mtx_relat)
gc()

Saving Results

# Save enhanced Seurat object
saveRDS(seurat_obj, "seurat_with_SCEVAN.rds")

# Save just the metadata
write.csv(
  seurat_obj@meta.data,
  "SCEVAN_metadata.csv",
  row.names = TRUE
)

Troubleshooting

Common Issues

Issue	Solution
Cell name mismatch	Check for `-` vs `.` in barcodes
Missing cells	Verify cells passed SCEVAN filtering
Empty CNA values	Check if cell is classified as “filtered”

Cell Name Formatting

# SCEVAN may convert "-" to "."
# Fix cell names if needed
colnames(count_mtx) <- gsub("-", ".", colnames(count_mtx))

# Or in Seurat object
seurat_obj <- RenameCells(
  seurat_obj,
  new.names = gsub("-", ".", colnames(seurat_obj))
)

Session Info

sessionInfo()
#> R version 4.4.0 (2024-04-24)
#> Platform: aarch64-apple-darwin20
#> Running under: macOS 15.6.1
#> 
#> Matrix products: default
#> BLAS:   /Library/Frameworks/R.framework/Versions/4.4-arm64/Resources/lib/libRblas.0.dylib 
#> LAPACK: /Library/Frameworks/R.framework/Versions/4.4-arm64/Resources/lib/libRlapack.dylib;  LAPACK version 3.12.0
#> 
#> locale:
#> [1] C
#> 
#> time zone: Asia/Shanghai
#> tzcode source: internal
#> 
#> attached base packages:
#> [1] stats     graphics  grDevices utils     datasets  methods   base     
#> 
#> loaded via a namespace (and not attached):
#>  [1] digest_0.6.39     desc_1.4.3        R6_2.6.1          fastmap_1.2.0    
#>  [5] xfun_0.56         cachem_1.1.0      knitr_1.51        htmltools_0.5.9  
#>  [9] rmarkdown_2.30    lifecycle_1.0.5   cli_3.6.5         sass_0.4.10      
#> [13] pkgdown_2.1.3     textshaping_1.0.4 jquerylib_0.1.4   systemfonts_1.3.1
#> [17] compiler_4.4.0    tools_4.4.0       ragg_1.5.0        bslib_0.9.0      
#> [21] evaluate_1.0.5    yaml_2.3.12       otel_0.2.0        jsonlite_2.0.0   
#> [25] rlang_1.1.7       fs_1.6.6          htmlwidgets_1.6.4

Zaoqu Liu

2026-01-24