In Situ UIDs for Spatial RNA Mapping Without Cell Dissociation
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Solution Overview
Problem
Current methods for sequencing DNA or RNA in individual cells require cell dissociation, which is detrimental for fragile cell types like neurons, and suffer from sequence-dependent bias and inaccuracy, especially at low copy numbers.
Innovation Solution
Randomized barcoding of DNA or cDNA before in situ amplification creates unique molecular identifiers (UIDs) for template molecules, allowing for the cross-linking of amplification products and sequencing at single-cell or subcellular resolution without cell dissociation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cell dissociation is performed for sequencing DNA or RNA in individual cells, then single-cell resolution is achieved, but cellular integrity is lost and fragile cell types like neurons are damaged
Solution Approach 1:
The patent applies preliminary action by performing in situ amplification and cross-linking of nucleic acid molecules within intact cells before any dissociation or lysis steps. The method establishes spatial relationships and generates sufficient signal amplification while cells remain in their native state, thereby achieving single-cell resolution without compromising cellular integrity or damaging fragile cell types
2Quantity of substance
If exponential PCR amplification is used for RNA sequencing, then signal amplification is achieved, but sequence-dependent bias and inaccuracy increase, especially at low copy numbers
Solution Approach 1:
The patent applies segmentation by dividing the amplification process into distinct phases: initial in situ amplification that maintains spatial information, followed by cross-linking to capture spatial relationships, and finally sequencing. This segmented approach allows signal amplification while preserving sequence accuracy by avoiding the biases inherent in traditional exponential PCR
Solution Approach 2:
The patent introduces cross-linking as an intermediary step between amplification and sequencing. This cross-linking mechanism captures spatial relationships and enables accurate reconstruction of original nucleic acid distributions without relying on exponential PCR amplification, thereby eliminating sequence-dependent bias while maintaining signal amplification
3Productivity
If bulk lysis of cell populations is performed, then high-throughput sequencing is enabled, but spatial information and associations of specific mRNA transcripts in individual cells are lost
Solution Approach 1:
The patent performs preliminary in situ amplification and cross-linking within intact cells before bulk processing. This establishes spatial relationships and generates sufficient signal while cells remain intact, allowing subsequent high-throughput sequencing to recover both quantitative and spatial information that would otherwise be lost in bulk lysis
4Measurement precision
If in situ amplification is performed without randomized barcoding, then spatial distributions can be recorded, but sequence-dependent bias and PCR amplification noise compromise accuracy
Solution Approach 1:
The patent introduces randomized barcodes as an intermediary element that bridges in situ amplification and sequencing. These barcodes are incorporated during in situ amplification and serve as unique identifiers that enable accurate tracking and quantification of original nucleic acid molecules, eliminating sequence-dependent bias while preserving spatial distribution information
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 the recording of spatial distributions of DNA or RNA molecules in non-dissociated cells with high accuracy and resolution, overcoming the limitations of existing technologies by maintaining cellular integrity and reducing sequence-dependent biases.
Implementation Method 1
The template DNA or cDNA is then amplified in situ by the polymerase chain reaction ('PCR') using primers that are complementary to sequences at the 5' and 3' ends of the template
Implementation Method 2
The primers also contain reverse-complementary 'overhang' sequences that allow amplicons to cross-link to one another during the PCR reaction
Data Source
AI summary
The present invention relates to molecular microscopy or volumetric imaging by proximal unique molecular identifiers (“UID”) reaction (“VIPUR”) microscopy methods to record the cellular co-localization and/or spatial distributions of arbitrary nucleic acid sequences, or other biomolecules tagged with nucleic sequences. The method involves one or both of two DNA sequence-components such as an α-UID, which may identify the targeted sequences-of-interest themselves and/or spatial beacons relative to which their distances are measured, and a- β-UID, which labels α-UID association events.