Cell-Free Chromatin H3 Isoform Profiling for Tissue Origin
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Solution Overview
Problem
Current methods for identifying the tissue of origin of circulating cell free nucleosomes and cfDNA in body fluids are non-specific and technically demanding, limiting their clinical utility for disease diagnosis and monitoring.
Innovation Solution
A method is developed to determine the H3 isoform composition of cell free histones or nucleosomes, using binding agents that specifically recognize H3.1, H3.2, H3t, or H3.3 histones to differentiate between nucleosomes originating from dividing and non-dividing cells, enabling precise identification of their tissue of origin.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If DNA sequence analysis is used to identify tissue of origin, then origin identification can be achieved in cases of different DNA sequences (e.g., fetal vs maternal), but it fails when all cells share the same DNA sequence (e.g., different tissues in same individual)
Solution Approach 1:
The patent applies local quality by exploiting the specific property that H3.3 histone isoform is predominantly incorporated into nucleosomes from non-dividing cells, while H3.1/H3.2 are from dividing cells. This localized biochemical distinction allows tissue origin identification without relying on DNA sequence variations, resolving the contradiction between measurement precision and adaptability across different tissue types.
Solution Approach 2:
The patent changes the measurement parameter from DNA sequence composition to histone isoform composition. By measuring the ratio of H3.3 to canonical H3 isoforms in cell-free nucleosomes, the method achieves tissue origin identification that is universally applicable regardless of whether cells share the same DNA sequence, thus resolving the technical contradiction.
2Measurement precision
If complex analysis methods like fragmentomics are used to identify cellular origin, then origin identification can be achieved, but the device complexity and technical demand increase significantly
Solution Approach 1:
The patent extracts the key distinguishing feature (histone isoform composition) from the complex nucleosome structure, allowing origin identification through a simplified measurement approach. Instead of performing comprehensive fragmentomics analysis, the method isolates and measures only the H3 histone isoform ratios, dramatically reducing device complexity while maintaining identification accuracy.
Solution Approach 2:
Instead of analyzing DNA fragments to infer cell origin (the conventional approach), the patent inverts the approach by analyzing the protein composition (histone isoforms) of nucleosomes to directly determine cellular origin. This inversion simplifies the analytical methodology while achieving the same identification goal.
3Reliability
If cell free nucleosome levels are measured to indicate cell death, then disease indication can be obtained, but the specificity of tissue origin information is lost
Solution Approach 1:
The patent adds another dimension to nucleosome analysis by measuring not just the quantity of cell-free nucleosomes but also their histone isoform composition. This dimensional expansion transforms the measurement from a single parameter (nucleosome level indicating cell death) to multiple parameters (total level plus H3.3/H3.1-3.2 ratio), simultaneously preserving disease indication reliability and recovering tissue origin information.
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 the accurate differentiation of nucleosomes and cfDNA sources, enhancing the clinical utility of cell free histones and nucleosomes as biomarkers for disease detection and monitoring, particularly in the central nervous system and organ transplantation.
Implementation Method 1
using binding agents that specifically recognize H3.1, H3.2, H3t, or H3.3 histones to differentiate between nucleosomes originating from dividing and non-dividing cells
Data Source
AI summary
The invention relates to methods and uses of cell free histone H3 isoforms H3.1, H13.2, H3t and/or H3.3 (or cell free nucleosomes containing said isoforms) of determining the origin of a cell free histone or cell free nucleosome in a body fluid sample as originating from a dividing or non-dividing cell.