Whole Blood Storage for Fixative-Free cfDNA Size Selection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for processing blood samples for cell-free DNA (cfDNA) analysis face challenges due to the need for specialized tubes and equipment for immediate high-speed centrifugation, leading to increased costs and inefficiencies, especially in settings without access to such facilities, and result in degradation of genomic material over time.
Innovation Solution
A method involving the storage of whole blood samples in a collection device without a fixative at temperatures between −20° C. and 35° C. for up to 9 days, followed by size selection of cfDNA less than 300 bp, and subsequent analysis to increase the fetal fraction for accurate sequencing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If specialized tubes with cross-linking agents are used to stabilize blood samples for extended storage, then sample integrity is maintained, but cost increases significantly
Solution Approach 1:
The patent replaces expensive specialized stabilization tubes with inexpensive, disposable standard tubes containing only EDTA anticoagulant. The tubes are designed for single use but at very low cost, eliminating the need for costly cross-linking agents while maintaining adequate sample integrity through proper handling procedures.
Solution Approach 2:
The patent extracts and removes the expensive cross-linking agents and complex stabilization components from the blood collection system. Only the essential EDTA anticoagulant is retained in the tube, separating the stabilization function from the collection container itself and achieving cost reduction while maintaining reliability.
2Manufacturing precision
If high-speed centrifugation is performed immediately after blood collection, then plasma separation quality is improved, but equipment requirements and operational complexity increase
Solution Approach 1:
The patent segments the plasma separation process into multiple stages: initial low-speed centrifugation to separate most cells, followed by a second centrifugation step, and finally filtration. This multi-stage approach achieves high plasma separation quality using equipment with progressively lower speed requirements, reducing overall device complexity.
Solution Approach 2:
The patent introduces dynamic, flexible handling procedures that allow laboratories to adapt the centrifugation and processing timeline to their available equipment. The method accommodates varying centrifugation speeds and timing while maintaining plasma quality through adjusted procedural parameters, making the system adaptable to different equipment capabilities.
3Quantity of substance
If blood samples are stored for extended periods without fixative, then cost and equipment requirements are reduced, but cfDNA degradation increases
Solution Approach 1:
The patent applies preliminary action by adding EDTA anticoagulant to the blood sample at the time of collection, which prevents coagulation and creates a stable environment for cfDNA preservation during storage. This preliminary protective measure enables extended storage without fixatives while maintaining cfDNA integrity.
Solution Approach 2:
The patent uses EDTA as an intermediary substance between the blood components and the storage environment. EDTA chelates calcium ions to prevent coagulation and creates a buffered environment that stabilizes cfDNA during extended storage at refrigerated temperatures, replacing the need for expensive cross-linking agents.
4Manufacturing precision
If filtration steps are added to plasma preparation, then cfDNA purity is improved, but processing time and operational complexity increase
Solution Approach 1:
The patent changes the physical parameters of the plasma preparation by using filtration with specific pore sizes (0.22 µm or 0.45 µm) to remove cellular debris and proteins. This parameter-based approach achieves high cfDNA purity through a single filtration step that can be performed quickly, reducing overall processing time compared to multiple sequential purification steps.
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 extended storage and processing of blood samples without fixatives, enhancing the fetal fraction and improving the quality of cfDNA for meaningful sequence analysis, thereby reducing costs and equipment requirements.
Implementation Method 1
storing the blood without fixative prior to isolating the cell-free DNA from the plasma at a temperature greater than −20° C. and less than 35° C. (such as room temperature or refrigeration temperatures)
Implementation Method 2
separating the cell free DNA by size of the cell free DNA and isolating the cell free DNA that is less than 300 bp
Data Source
AI summary
The present invention relates to storing and testing for abnormalities in cell free DNA (cfDNA) from blood, such as in maternal blood or blood for cancer screening.