Digital Droplet PCR for Single Cell Transgene Quantification
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Solution Overview
Problem
Current methods for genetic characterization of single cells in stem cell gene therapy lack efficiency and accuracy in evaluating the engraftment and distribution of transduced cells, particularly in bone marrow, which is crucial for assessing treatment efficacy in primary immunodeficiencies.
Innovation Solution
A single cell-based digital droplet PCR (sc-ddPCR) method is developed, where a single cell is encapsulated in a droplet with PCR reagents, allowing for direct amplification and detection of target nucleic acids within the droplet, enabling precise quantification of transgene-positive cells and vector integration levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional PCR methods are used for genetic characterization of single cells, then the amplification process can be performed, but the measurement precision and accuracy in evaluating engraftment and distribution of transduced cells is insufficient
Solution Approach 1:
The invention divides the amplification reaction into multiple separate reactions, each performed in an individual compartment. This segmentation allows for digital counting of amplification events, significantly improving measurement precision for detecting transgene-positive cells and vector integration levels without requiring complex instrumentation beyond standard PCR equipment.
Solution Approach 2:
The invention introduces compartments as intermediaries to separate and isolate individual target molecules or cells. Each compartment acts as an independent reaction chamber, enabling the detection of single-molecule amplification events. This intermediary structure transforms the continuous signal of conventional PCR into discrete, countable events, thereby enhancing measurement precision.
2Measurement precision
If single cell-based digital droplet PCR is implemented, then measurement precision and accuracy are improved, but the device complexity and operational complexity increase
Solution Approach 1:
The reaction system is segmented into multiple compartments, with each compartment containing a single target molecule or cell. This segmentation enables digital counting of positive events, dramatically improving accuracy in evaluating engraftment and distribution of transduced cells. The segmented approach transforms qualitative PCR results into quantitative data through simple counting of positive compartments.
Solution Approach 2:
The invention creates multiple copies of the reaction system in the form of numerous identical compartments. Each compartment is a copy of the basic reaction setup, allowing parallel processing of many samples simultaneously. This copying strategy maintains ease of operation by using replicated simple units rather than requiring complex single-sample analysis equipment.
3Measurement precision
If multiple compartments are used for amplification reactions, then the precision of quantification is improved, but the loss of time and processing complexity increases
Solution Approach 1:
The invention segments the quantification process into multiple parallel reactions across many compartments. While each individual reaction takes the same amount of time as conventional PCR, the segmented approach allows simultaneous processing of numerous samples, improving precision of quantification through statistical counting without proportionally increasing total processing time.
Solution Approach 2:
The invention maintains continuous useful action by performing all amplification reactions simultaneously in parallel across multiple compartments during a single PCR cycling process. This eliminates sequential processing delays and ensures that the increased number of reactions does not linearly increase the total time required, thereby improving precision without excessive time penalty.
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 method provides a detailed and accurate assessment of transgene distribution in patients, revealing skewed engraftment patterns and vector copy numbers, aiding in the evaluation of gene therapy efficacy and informing treatment strategies.
Implementation Method 1
A single cell is encapsulated in a droplet with PCR reagents, allowing for direct amplification and detection of target nucleic acids within the droplet
Data Source
AI summary
A method of amplifying a target nucleic acid (polynucleotide) contained in a particle including an enclosing lipid bilayer membrane according to the present invention includes the steps of:lysing the particle which is stored in a compartment constituted by a liquid in an amount of 100 μl or less; andamplifying the target nucleic acid in the compartment.