CEST MRI Reporter Genes for Cell Tracking

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Solution Overview

Problem

Current MRI cell tracking methods using iron oxide particles face limitations such as high iron requirements for detection, potential adverse effects on cellular function, and reduced detection efficiency due to cell division, as well as challenges in monitoring cells over time and across the blood-brain barrier.

Innovation Solution

Development of a new class of reporter genes based on lysine-rich and arginine-rich proteins that utilize chemical exchange saturation transfer (CEST) MRI technology, allowing for non-invasive, substrate-free imaging of cells with high sensitivity and the ability to differentiate between live and dead cells.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If iron oxide particles are used for MRI cell tracking, then cell detection is possible, but high iron requirements and potential adverse effects on cellular function occur

Engineering Contradiction:

Improvecell detection sensitivityVSAvoidadverse effects on cellular function

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces persistent iron oxide particles with a temporary CEST effect that disappears after imaging. The contrast mechanism uses exchangeable protons in proteins that are saturated by RF pulses, creating a transient signal without requiring long-lasting iron deposits in cells, thus eliminating chronic iron toxicity while maintaining detection capability

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The invention changes the physical basis of contrast from magnetic susceptibility (iron oxide) to chemical exchange saturation transfer (CEST). By saturating exchangeable protons in cellular proteins at specific offset frequencies and detecting the transfer to water protons, the system achieves cell detection without iron, using instead the chemical and magnetic properties of protein protons

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If iron oxide particles are used for MRI cell tracking, then cell detection is possible, but detection efficiency is reduced due to cell division

Engineering Contradiction:

Improvecell detection sensitivityVSAvoiddetection efficiency

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The CEST effect utilizes the cell's own protein protons as the contrast mechanism. Since proteins are abundant in all living cells and the CEST effect depends on exchangeable protons that are naturally present in cellular proteins, the system automatically provides contrast without requiring external iron loading, maintaining detection efficiency even as cells divide and proliferate

Inventive Principle:

Principle #25Self-service

3Ease of operation

If conventional MRI methods are used, then imaging is possible, but substrate administration is required and blood-brain barrier penetration is problematic

Engineering Contradiction:

Improveimaging capabilityVSAvoidsubstrate administration requirement

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The method eliminates the need for exogenous substrate administration by using the cell's own protein protons as the contrast mechanism. The CEST effect is generated endogenously within cells through the exchange of protons between cellular proteins and water, removing the complexity of substrate delivery systems and blood-brain barrier penetration requirements

Inventive Principle:

Principle #25Self-service

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

Enables sensitive, non-invasive, and repetitive monitoring of cell biodistribution and migration without the need for exogenous substrates, maintaining detection efficiency even after cell division and across the blood-brain barrier, and providing continuous monitoring of rapidly dividing cells.

Implementation Method 1

chemical exchange saturation transfer (CEST) MRI technology

Methodology Applied

Scientific EffectChemical exchange saturation transfer:

Implementation Method 2

exchangeable protons in proteins that exchange with water protons

Methodology Applied

Scientific EffectProton exchange:

Implementation Method 3

irradiated at a specific off-resonance radio-frequency (RF frequency)... saturation of exchangeable protons

Methodology Applied

Scientific EffectRadio-frequency saturation:

Implementation Method 4

magnetic resonance imaging (MRI)... water protons provide the MRI signal

Methodology Applied

Scientific EffectMagnetic resonance:

Data Source

PatentUS8236572B2Chemical exchange saturation transfer based MRI using reporter genes and MRI methods related thereto

Publication Date: 2012.08.07 JOHNS HOPKINS UNIVERSITY

AI summary

Featured are a new class of reporter genes including reporter compositions as well as methods, MRI systems and MRI imaging kits related thereto. The genes according to the present invention provide MR contrast when the sample/subject is irradiated at a specific off-resonance radio-frequency (RF frequency), where the contrast mechanism utilizes chemical exchange saturation transfer (CEST) technique for imaging.