Engineered Cell Surface Molecule for HIV Resistance
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Solution Overview
Problem
Current gene-editing based stem cell therapies for HIV face challenges in achieving high purity of HIV-resistant cells due to the lack of a selection marker and potential off-target site cleavage with CRISPR-Cas9, making it difficult to screen or enrich bi-allelic CCR5 knockout HSCs effectively.
Innovation Solution
Engineering cells to express a surface molecule with a binding moiety that specifically binds to HIV antigens or T cell surface antigens, such as CCR5, CD4, or CXCR4, and a membrane domain for tethering, which confers HIV resistance and can be enriched based on the expressed surface molecule, avoiding the need for selection markers and reducing off-target effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If CRISPR-Cas9 is used to edit CCR5 in HSPCs, then HIV resistance can be achieved, but off-target site cleavage occurs and selection marker is lost
Solution Approach 1:
The patent introduces a surface molecule as an intermediary that binds to HIV antigens or T cell surface antigens, serving as a protective barrier between the engineered cell and HIV. This mediator approach allows HIV resistance without requiring CRISPR-Cas9 editing, thereby avoiding off-target effects while achieving the same protective outcome.
Solution Approach 2:
The patent extracts the essential protective function (HIV resistance) from the gene-editing process itself and implements it through a separate mechanism (surface molecule expression). By taking out the need for CCR5 knockout and replacing it with a binding molecule that blocks HIV entry, the solution achieves HIV resistance without the harmful off-target cleavage associated with CRISPR-Cas9.
2Reliability
If CRISPR-Cas9 editing is performed ex vivo, then some HSPCs can be edited to provide protection, but only a fraction achieve the desired CCR5 indel efficiency
Solution Approach 1:
The surface molecule acts as an intermediary that provides HIV protection through binding to HIV antigens or T cell surface antigens like CCR5, CD4, or CXCR4. This approach bypasses the need for precise CRISPR-Cas9 editing entirely, achieving reliable HIV protection without the manufacturing precision challenges of achieving high CCR5 indel efficiency.
Solution Approach 2:
The patent changes the approach from modifying the CCR5 gene itself (requiring high precision editing) to expressing a surface molecule that binds to HIV or T cell surface antigens. This parameter change from gene knockout to protein expression eliminates the need for high CCR5 indel efficiency while maintaining reliable HIV protection.
3Measurement precision
If a selection marker is used to screen edited HSCs, then HIV-resistant cells can be identified, but the process becomes complex and less effective
Solution Approach 1:
The surface molecule serves as a natural selection marker by itself, as its expression on the cell surface provides both the HIV resistance mechanism and a means to identify and enrich for successfully engineered cells. This eliminates the need for separate selection marker systems, reducing complexity while maintaining screening accuracy.
Solution Approach 2:
The surface molecule performs multiple functions simultaneously: it provides HIV resistance through binding to HIV antigens or T cell surface antigens, and it serves as a selection/enrichment marker for identifying engineered cells. This multi-functionality eliminates the need for separate selection markers, simplifying the overall process while maintaining measurement precision.
4Reliability
If high purity of HIV-resistant cells is achieved through gene editing, then effective protection is provided, but the process requires complex screening and enrichment
Solution Approach 1:
The surface molecule serves as an intermediary that both provides HIV resistance and enables easy identification and enrichment of engineered cells through its surface expression. This dual role simplifies the manufacturing process by eliminating complex screening and enrichment procedures while achieving high purity HIV-resistant cell populations.
Solution Approach 2:
The surface molecule performs dual functions: providing HIV resistance through antigen binding and serving as a selection marker for easy cell enrichment. This multi-functionality directly addresses the manufacturing difficulty by making the enrichment process straightforward while maintaining reliable HIV resistance.
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 attainment of a highly pure HIV-resistant cell population with enhanced herd immunity, where cells expressing the surface molecule not only resist HIV infection but also protect susceptible cells, achieving a significant increase in resistance and immunity against HIV.
Implementation Method 1
a binding moiety, wherein the binding moiety i) specifically binds to a T cell surface antigen and prevents the binding of the T cell surface antigen to its cognitive ligand on HIV
Implementation Method 2
specifically binds to a HIV antigen competitively with 10-1074, 10E8, or PGT121, or binds to the same epitope as that of 10-1074, 10E8, or PGT121 and prevents HIV from infecting the engineered cell
Implementation Method 3
a membrane domain that tethers the molecule to the membrane or facilitates the tethering of the surface molecule to the membrane
Data Source
AI summary
Provided are engineered cells (such as stem cells or T cells) that have a surface molecule comprising a membrane-tethered binding moiety that binds to a T cell surface antigen (such as CCR5, CD4 or CXCR4) or a HIV antigen, or a membrane tethered inhibitory moiety that inhibits the membrane fusion of HIV (such as C34). Also provided are methods of making and using these engineered cells.