Single Cell Nucleic Acid Analysis via Droplet Barcoding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for analyzing mRNA content in cells, such as microarray hybridization and direct sequencing, are limited in their ability to analyze alternative splicing, promoters, and polyadenylation signals, and fail to capture functional information from single cells or observe dynamic processes like the cell cycle, due to reliance on bulk mRNA samples and lack of suitable cell-surface markers.
Innovation Solution
The development of methods and compositions for nucleic acid analysis from single cells or their organelles, using droplets and beads with unique barcodes, allowing for multiplexed single cell gene expression analysis by releasing nuclei or organelles, synthesizing cDNA, and incorporating tags for sequencing library preparation, including tagmentation to introduce barcodes and adapters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If bulk mRNA analysis is performed using microarray hybridization or direct sequencing, then throughput and sensitivity are improved, but the ability to capture single cell variability and dynamic processes is lost
Solution Approach 1:
The patent segments the bulk mRNA sample into individual single-cell mRNA samples by isolating single cells first. Each single cell is then processed separately to generate cDNA with unique cell-specific barcodes, allowing subsequent pooling and sequencing while preserving single-cell resolution. This segmentation enables both high throughput (by processing many cells) and retention of single-cell variability information.
Solution Approach 2:
The patent introduces cell-specific barcodes as intermediary molecular tags that link individual cells to their mRNA transcripts. These barcodes are incorporated into the cDNA during reverse transcription and serve as identifiers that allow computational separation of transcripts from different cells after pooling. This intermediary enables the system to handle bulk samples while maintaining single-cell information.
2Loss of information
If single cells are isolated for study, then single cell variability can be captured, but the number of cells is insufficient to represent natural variation
Solution Approach 1:
The patent merges multiple single-cell cDNA samples into a single pooled library after individual barcode assignment. By combining cDNA from many individually barcoded cells into one pool for sequencing, the method captures both single-cell resolution and population-level variation. This merging allows analysis of natural variation across large numbers of cells while maintaining the ability to trace transcripts to individual cells.
3Measurement precision
If cDNA libraries are prepared from single cells, then single cell gene expression can be analyzed, but the complexity of the preparation process increases
Solution Approach 1:
The patent employs universal primers and reagents that work across all single-cell samples simultaneously. The cell-specific barcodes are incorporated using universal reverse transcription primers, and the same pooling and sequencing protocol applies to all samples. This universality simplifies the overall process by allowing parallel processing of many cells with a single set of reagents and protocols, reducing the operational complexity despite the detailed molecular steps.
4Reliability
If microarray hybridization is used for gene expression profiling, then known genes can be analyzed, but alternative splicing, promoters, and polyadenylation signals cannot be detected
Solution Approach 1:
The patent replaces the microarray hybridization mechanism with direct cDNA sequencing. Instead of relying on pre-designed probes that can only detect known genes, the method uses reverse transcription to convert mRNA to cDNA followed by sequencing, which can read any nucleotide sequence. This substitution enables detection of alternative splicing variants, promoter regions, and polyadenylation signals that were invisible to microarray technology, while maintaining reliable gene expression measurement.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables detailed analysis of gene expression in single cells, capturing individual cell variability and dynamic processes, with improved sensitivity and throughput, allowing for whole transcriptome sequencing and digital gene expression assays.
Implementation Method 1
A first strand of cDNA is synthesized from the mRNA in each individual mRNA sample with a first strand synthesis primer
Implementation Method 2
the second strand of cDNA is synthesized using the TSO primer
Implementation Method 3
tagmentation to introduce barcodes and adapters
Data Source
AI summary
Presented herein are methods and compositions for multiplexed single cell gene expression analysis. Some methods and compositions include the use of droplets and/or beads bearing unique barcodes such as unique molecular barcodes (UMI).