Single-Cell Chromatin Profiling with Droplet Barcoding for Drug Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current chromatin profiling technologies fail to study cellular heterogeneity and detect cell-to-cell variation in chromatin states, particularly in the context of drug resistance, due to limitations in single-cell epigenetic profiling methods like Drop-ChIP, which suffer from low information recovery and amplification bias.
Innovation Solution
A droplet microfluidics-based method for single-cell chromatin profiling that uses hydrogel beads carrying unique DNA sequences and asymmetric nucleosome barcoding, allowing for high-resolution profiling of up to 10,000 loci per cell, with improved amplification efficiency and reduced bias.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional ChIP-seq method is used for genome-wide mapping of epigenetic modifications, then high-quality binding site profiles can be generated, but a large number of cells are required and cellular heterogeneity cannot be studied
Solution Approach 1:
The patent segments the bulk ChIP-seq process into single-cell units by encapsulating individual cells in droplets, allowing parallel processing of thousands of cells while maintaining single-cell resolution. This enables study of cellular heterogeneity while still generating high-quality profiles through pooling of indexed single-cell ChIP samples.
Solution Approach 2:
The patent applies preliminary barcoding of nucleosomes with unique molecular identifiers (UMIs) before immunoprecipitation. This allows tracking of individual nucleosome origins and enables accurate quantification of enrichment at single-cell level, resolving the contradiction between low input material and measurement precision.
2Measurement precision
If chromatin from single cells is immunoprecipitated to achieve single-cell resolution, then cellular heterogeneity can be detected, but highly variable results and high experimental noise are obtained
Solution Approach 1:
The patent merges indexed chromatin from multiple single cells into pooled samples for immunoprecipitation. This combines the benefits of single-cell resolution (through barcode tracking) with the statistical power of bulk analysis, reducing experimental noise while maintaining ability to detect cellular heterogeneity.
Solution Approach 2:
The patent uses molecular copying through barcode amplification to overcome low input material limitations. Each nucleosome is copied with its unique barcode, allowing sufficient material for immunoprecipitation while maintaining single-cell identification capability, thus reducing experimental noise.
3Loss of information
If only indexed nucleosomes are amplified and sequenced in single-cell ChIP-seq, then single-cell information is retained, but information recovery is limited and amplification bias occurs
Solution Approach 1:
The patent performs preliminary asymmetric barcoding of nucleosomes with unique molecular identifiers before immunoprecipitation. This allows comprehensive tracking of all nucleosome fragments regardless of symmetry, maximizing information recovery while maintaining single-cell resolution through UMI-based quantification.
Solution Approach 2:
The patent changes the barcoding strategy from symmetric dual-end labeling to asymmetric single-end labeling with UMIs. This parameter change increases the proportion of recoverable nucleosomes and reduces amplification bias by allowing stochastic amplification of all indexed fragments while maintaining quantitative accuracy through UMI counting.
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
The method achieves a 5- to 10-fold increase in enriched loci per cell, enabling precise identification of chromatin states and potential biomarkers for drug resistance, facilitating diagnosis and prognosis of drug-resistant cell populations.
Implementation Method 1
A droplet microfluidics-based method for single-cell chromatin profiling that uses hydrogel beads carrying unique DNA sequences
Implementation Method 2
following the steps of compartmentalization, lysis and chromatin fragmentation by micrococcal nuclease of the cell in droplets
Implementation Method 3
The two emulsions are reinjected in a fusion device, the barcode drops (100 pl) and the nucleosome drops (45 pl) are paired asymmetrically and an electric field triggers the fusion. Fused droplets are scanned one-by-one by a laser beam and the composition of each droplet is analyzed in real time.
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3
AI summary
An aspect of the invention relates to a method for the diagnosis and/or prognosis of drug resistance, wherein single cell chromatin states are profiled in cells obtained from a subject by using a microfluidic system.