In Situ Hybridization Fixation for Small RNA Retention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for in situ hybridization (ISH) fail to effectively detect small nucleic acids such as small non-coding RNA (sncRNA), microRNA (miRNA), PIWI-interacting RNA (piRNA), and antisense oligonucleotides (ASO) due to inadequate cross-linking during tissue fixation, leading to their release and dispersal from tissues.
Innovation Solution
A two-step fixation process involving an initial fixation with agents like formaldehyde or glutaraldehyde followed by a post-fixation with an aldehyde-containing fixative, such as formaldehyde or glutaraldehyde, enhances the retention of these small nucleic acids within the tissue microenvironment, improving detection sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemical fixatives are used to preserve tissue specimens for histopathology, then long mRNA species can be detected by RNA ISH technology, but small nucleic acids are inadequately cross-linked leading to their release and dispersal from tissues
Solution Approach 1:
The patent applies a preliminary cross-linking step using agents like glutaraldehyde or EDC before the standard formalin fixation. This preliminary action creates initial cross-links that prevent small nucleic acids from dispersing during subsequent processing steps, thereby resolving the contradiction between maintaining tissue morphology and retaining small nucleic acids.
Solution Approach 2:
The patent employs a composite fixation approach combining multiple chemical agents (e.g., glutaraldehyde plus formalin, or EDC plus formalin) to achieve both adequate cross-linking for small nucleic acid retention and proper tissue preservation. This composite material strategy allows simultaneous detection of both small and long nucleic acid species.
2Shape
If standard fixation protocols are used, then tissue morphology is preserved, but detection sensitivity for small RNAs is poor due to inadequate cross-linking
Solution Approach 1:
The preliminary cross-linking step with glutaraldehyde or EDC is performed before standard fixation to secure small nucleic acids in place. This preliminary action enhances detection sensitivity without compromising the subsequent tissue morphology preservation achieved by standard fixation protocols.
Solution Approach 2:
The patent modifies the fixation parameters by introducing additional cross-linking agents and adjusting fixation times and concentrations. These parameter changes increase the cross-linking density sufficient to retain small RNAs while maintaining tissue morphology suitable for histopathological examination.
3Measurement precision
If cross-linking density is increased to retain small nucleic acids, then detection sensitivity improves, but tissue processing complexity increases
Solution Approach 1:
The preliminary cross-linking step is designed to be a simple, single-step process that can be integrated into existing fixation workflows. By performing cross-linking before standard fixation, the method achieves enhanced small nucleic acid retention without significantly increasing overall process complexity.
Solution Approach 2:
The patent uses intermediary cross-linking agents (glutaraldehyde, EDC) that facilitate small nucleic acid retention through moderate cross-linking. These intermediaries enable effective small RNA preservation while allowing the subsequent standard fixation process to proceed without major modifications, thus limiting complexity increase.
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
The method preserves small nucleic acids within their native tissue microenvironment, enabling enhanced detection sensitivity and spatial resolution of target nucleic acids like sncRNAs, miRNAs, siRNAs, and ASOs, while being fully compatible with standard ISH assays.
Implementation Method 1
Preservation of tissue specimens for histopathology has relied on cross-linking proteins and nucleic acids using chemical fixatives
Implementation Method 2
A two-step fixation process involving an initial fixation with agents like formaldehyde or glutaraldehyde followed by a post-fixation with an aldehyde-containing fixative
Data Source
AI summary
A method of detecting target nucleic acids, including small non-coding RNAs (sncRNAs), microRNAs (miRNAs), small interfering RNAs (siRNAs), PIWI-interacting RNA (piRNA), or antisense oligonucleotides (ASO) molecules, in a cell, comprising a post-fixation step using an aldehyde-containing fixative after the initial fixation step prior to in situ hybridization.