Fetal DNA Isolation via Microchannel Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for obtaining chromosomal DNA of fetal cell origin from maternal blood samples suffer from low purity due to contamination with maternal white blood cells and non-nucleated red blood cells, making it difficult to isolate DNA from nucleated red blood cells of fetal origin.
Innovation Solution
A method involving specific labeling of red blood cells and nucleic acids in a maternal blood sample, followed by cell sorting to increase the purity of nucleated red blood cells, and subsequent separation and extraction of chromosomal DNA at a single-cell level, allowing for molecular biological analysis to distinguish fetal DNA.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If density gradient centrifugation method is used to concentrate NRBCs, then the concentration of NRBCs is improved, but the purity is worsened due to contamination with maternal WBCs
Solution Approach 1:
The patent divides the blood cell population into multiple fractions based on size using a microchannel chip with varying channel widths. NRBCs are separated into a specific size range (6-12 μm) that distinguishes them from both maternal WBCs and non-nucleated RBCs, achieving both concentration and high purity simultaneously through sequential size-based segmentation
Solution Approach 2:
The patent applies different selection criteria to different stages of the process: initial concentration uses density gradient centrifugation, then size-based microchannel filtration targets specific NRBC dimensions, and finally molecular biological analysis confirms fetal origin. Each stage optimizes for local requirements rather than attempting to solve all problems at once
2Difficulty of detecting and measuring
If morphological observation and May-Giemsa staining are used to isolate candidate NRBCs, then the identification capability is improved, but the complexity of the process increases
Solution Approach 1:
The patent replaces manual morphological observation and staining procedures with automated molecular biological analysis. PCR amplification of fetal-specific genetic markers (Y chromosome sequences for male fetuses) provides objective, quantifiable identification without requiring manual microscopy or complex staining protocols
Solution Approach 2:
The patent transitions from qualitative morphological parameters (cell shape, size under microscope) to quantitative molecular parameters (presence/absence of specific DNA sequences). This parameter change enables automated detection and eliminates subjectivity in cell identification
3Manufacturing precision
If single-cell level separation and independent DNA extraction are performed for each blood cell, then the purity of fetal DNA is improved, but the time and labor required increase significantly
Solution Approach 1:
The patent performs size-based pre-separation using the microchannel chip before DNA extraction. By filtering and concentrating NRBCs in the 6-12 μm size range prior to extraction, the system reduces the total number of cells requiring individual processing, thereby reducing overall time while maintaining single-cell extraction purity for the target population
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 enables the isolation of chromosomal DNA from nucleated red blood cells of fetal origin with high purity, improving the efficiency and accuracy of noninvasive prenatal genetic testing by reducing contamination from maternal cells.
Implementation Method 1
a fraction which is obtained from a maternal blood sample by fractionating blood cells in the maternal blood sample based on their sizes and removing at least some of non-nucleated RBCs from the blood cells
Implementation Method 2
specifically labeling red blood cells (RBCs) and nucleic acids in a fraction A
Implementation Method 3
obtaining a fraction B having increased purity of NRBCs by sorting out the labeled blood cells in the fraction A by at least cell sorting
Data Source
AI summary
In the present invention, a fraction (A) is labeled, the fraction (A) being a fraction obtained from a maternal blood sample and in which nucleated red blood cells (NRBCs) are concentrated in a population of whole blood cells. Then, a fraction (B) having increase purity of NRBCs is obtained by sorting out blood cells in the labeled fraction A by at least cell sorting. Next, fractions (C) are obtained by separating each blood cell in the fraction (B) at a single-cell level and independently performing a process for extracting a nucleic acid for each separated blood cell, each of the fractions (C) containing a nucleic acid distinguishable at a single-cell level. Then, a fraction (D) containing a nucleic acid derived from a fetus is sorted out from a group of fractions (C) by performing a molecular biological analysis for each of the fractions (C).