Single-Cell Nucleic Acid Analysis via Segmented WGA
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Solution Overview
Problem
Conventional polymerase chain reaction (PCR) methods are inadequate for reliable and reproducible analysis of genomic DNA or RNA from small samples or single cells, as they fail to ensure sufficient amplification of target nucleic acids for detection.
Innovation Solution
The method involves whole genome amplification (WGA) followed by preamplification and amplification of specific target nucleic acids using techniques like primer extension PCR, degenerated oligonucleotide primed PCR, and multiple displacement amplification, along with reverse transcription for RNA analysis, to produce multiple copies of the genome and increase the likelihood of complete amplification of target nucleic acids, which are then detected using quantitative real-time PCR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional PCR is used to analyze nucleic acids from single cells or small samples, then the analysis can be performed with simple equipment and procedures, but the amplification is insufficient and reproduction is inadequate
Solution Approach 1:
The amplification process is divided into two distinct stages: whole genome amplification (WGA) followed by specific target amplification. The WGA stage uses random primers to amplify all genomic DNA, creating multiple copies of the entire genome. The second stage then amplifies specific target sequences from these pre-amplified products. This segmentation allows each stage to be optimized independently, ensuring sufficient amplification for detection while maintaining reproducibility.
Solution Approach 2:
Whole genome amplification is performed as a preliminary step before specific target amplification. This pre-amplification ensures that sufficient template DNA is available for the subsequent specific PCR, eliminating the insufficient amplification problem that plagues direct single-cell PCR. The preliminary WGA action creates a robust foundation for reliable and reproducible target detection.
2Quantity of substance
If whole genome amplification is performed for many cycles to ensure complete amplification, then target nucleic acids are sufficiently amplified for detection, but the reaction reaches plateau and amplification efficiency decreases
Solution Approach 1:
The amplification process is segmented into two phases with different cycle numbers. The WGA phase uses a limited number of cycles (3-10 cycles) to generate sufficient template without reaching plateau. The second specific amplification phase then uses standard PCR cycles (25-35 cycles) to generate detectable amounts of target product. This segmentation allows the system to avoid plateau effects in the first phase while achieving sufficient quantity in the second phase.
Solution Approach 2:
The WGA stage performs partial amplification (incomplete genome coverage) with fewer cycles, intentionally leaving some amplification capacity unused. This partial action prevents the reaction from reaching plateau, maintaining high efficiency. The subsequent specific target amplification then completes the amplification process, achieving both sufficient quantity and high efficiency.
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 allows for reliable analysis of nucleic acids from single cells, including preimplantation embryos, stem cells, and cancer cells, by ensuring complete amplification and detection of target nucleic acids, enhancing the accuracy of genotyping and RNA expression studies.
Implementation Method 1
performing whole genome amplification of the genome of a single cell to produce an amplified genome
Implementation Method 2
preparing DNA from the RNA from a single cell
Data Source
AI summary
The present invention provides methods for analysis of genomic DNA and/or RNA from small samples or even single cells. Methods for analyzing genomic DNA can entail whole genome amplification (WGA), followed by preamplification and amplification of selected target nucleic acids. Methods for analyzing RNA can entail reverse transcription of the desired RNA, followed by preamplification and amplification of selected target nucleic acids.