Single-Step cDNA Synthesis for Spatial Analysis
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Solution Overview
Problem
Current spatial analysis methods fail to provide comprehensive data on the abundance and location of analytes in biological samples, particularly in intact tissues, as they either focus on limited analytes or single cells without considering the spatial context.
Innovation Solution
The method involves contacting a biological sample with a substrate containing capture probes with spatial barcodes, hybridizing analytes, and performing reverse transcription and second strand synthesis in a single reaction to determine the sequence of spatial barcodes and analytes, allowing for the identification of analyte abundance and location.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate reverse transcription and second strand synthesis reactions are performed, then reaction conditions can be optimized for each step, but processing time and operational complexity increase
Solution Approach 1:
The patent combines reverse transcription and second strand synthesis into a single multiplexed reaction by co-immobilizing reverse transcriptase and DNA polymerase on magnetic beads. This allows both enzymatic activities to occur simultaneously in one reaction vessel, eliminating the need for separate reaction steps while maintaining optimized conditions for both processes through the use of enzyme-specific activation sequences in the oligonucleotide probe design.
Solution Approach 2:
The magnetic bead support serves multiple functions: it acts as a solid phase for immobilizing both enzymes, provides a platform for sequential enzyme activation through temperature cycling, and enables easy separation of reaction components. This multi-functional design allows a single system to perform what previously required multiple separate reaction setups.
2Reliability
If multiple enzymatic reactions are performed in sequence, then each reaction can be controlled independently, but the number of operational steps and potential sources of error increase
Solution Approach 1:
The patent merges multiple enzymatic reactions into a single multiplexed process by immobilizing both reverse transcriptase and DNA polymerase on the same magnetic bead support. The sequential activation of enzymes is achieved through temperature-dependent conformational changes in the oligonucleotide probe, which exposes different binding sites at different temperatures, thereby controlling reaction sequence without requiring separate operational steps.
Solution Approach 2:
The system uses temperature cycling to automatically control the sequence of enzymatic reactions. At lower temperatures, the oligonucleotide probe structure favors reverse transcriptase activity, while at higher temperatures, it favors DNA polymerase activity. This self-regulating mechanism eliminates the need for manual intervention to switch between reactions, reducing operational complexity while maintaining reliable control.
3Loss of information
If comprehensive analyte data is collected from multiple analytes, then information completeness improves, but data processing and analysis complexity increase
Solution Approach 1:
The patent employs oligonucleotide probes with unique sequences for each target analyte, allowing specific recognition and binding to different mRNA molecules. Each probe is designed with local sequence complementarity to its target, enabling simultaneous detection of multiple analytes through a single reaction mixture. The magnetic beads with immobilized enzymes process all these specific interactions in parallel, generating distinct cDNA products that can be individually identified through sequencing.
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
This approach enhances the efficiency and sensitivity of spatial analysis by combining reverse transcription and second strand synthesis, providing high-resolution data on multiple analytes within biological samples while maintaining native spatial context.
Implementation Method 1
generating a complementary DNA (cDNA) molecule of the analyte by reverse transcription
Implementation Method 2
performing second strand synthesis of the cDNA molecule by contacting the analyte with a composition comprising a reverse transcription enzyme and a strand-displacing polymerase
Implementation Method 3
hybridizing the analyte to the capture probe
Data Source
AI summary
Provided herein are methods of identifying the spatial location of a nucleic acid in a biological sample. In some embodiments, the methods employ a template switching oligonucleotide. In some embodiments, the methods extend the capture probe to create a complementary DNA (cDNA) molecule of a capture analyte and produce second strand in one reaction.