Computational Service
Cell Line Models
Scoped After Feasibility Review
Service Overview
Knock-in is considerably harder than knockout because the desired outcome is one specific sequence rather than any disruptive one. Most failures trace to the design: a cut site too far from the intended edit, homology arms of the wrong length for the delivery format, or a donor that is re-cut after successful integration. We design the donor and the screening strategy around those failure modes, and specify how correct, single-copy integration will be demonstrated.
Key Features & Advantages
Cut Site Placed Close To The Edit
HDR efficiency falls sharply with distance between the cut and the intended change, so guide selection is driven by proximity to the edit rather than by cutting score alone.
Re-Cutting Prevented By Design
Silent mutations in the PAM or seed region are designed into the donor so that a correctly edited allele is not cut again, which is a frequent and avoidable cause of low knock-in rates.
Homology Arms Matched To Format
Arm lengths are chosen for the donor format in use — single-stranded oligonucleotide, plasmid or linear template — since the optimum differs substantially between them.
Screening Made Tractable
Junction PCR strategy, copy number assessment and sequencing plan are designed with the donor, so correct clones can be distinguished from random integrants.
Where This Service Is Used
1Introducing a point mutation to model a patient variant in an isogenic background
2Tagging an endogenous gene with a fluorescent or affinity tag at its native locus
3Inserting a reporter cassette under endogenous regulatory control
4Creating conditional or inducible alleles for essential genes
5Correcting a mutation to generate a matched control line
How the Work Is Performed
1Locus and sequence analysis around the intended edit, including repeats and regulatory elements
2Guide selection weighted by proximity to the edit site as well as predicted activity and specificity
3Donor design with homology arm optimisation for the chosen delivery format
4Silent mutation planning to block re-cutting while preserving coding sequence and splice signals
5Junction PCR, copy number and sequencing strategy design for clone screening
6Assessment of tag placement effects on folding, localisation and function where a tag is inserted
What We Need From You
1Target locus and the exact sequence change required, with the reference build
2Cell line, delivery method and donor format available to you
3For tagging, the tag identity and the terminus preferred, with any functional constraints
4Previous knock-in attempts at the locus and what was observed
What You Receive
1Complete donor sequence, annotated, ready for synthesis or oligonucleotide order
2Ranked guide designs with off-target assessment and the proximity rationale
3Silent mutation plan with the coding and splicing consequences checked
4Screening strategy: junction primers, copy number assay and sequencing plan
5Notes on expected efficiency and realistic clone numbers to screen
Questions We Are Asked Before Scoping
Why was our knock-in efficiency so low?
▸The usual causes are cut-to-edit distance, re-cutting of the corrected allele, unsuitable arm length for the donor format, or a cell line with low HDR activity. The design review usually identifies which applies.
Where should a tag go?
▸It depends on the protein. We model both termini for folding, localisation signals and known functional regions, and recommend the placement least likely to disturb function.
How many clones will we need to screen?
▸It varies widely by locus, cell line and delivery. We give a realistic range in the design report rather than a single number, and design the screening assay to keep that effort manageable.
Interpretation and Limitations
This is a computational (in silico) service. Designs and predictions prioritise hypotheses and direct experimental effort; they do not by themselves establish that an edit, construct, molecule or assay will perform as intended. Laboratory execution — editing, cloning, expression, synthesis and testing — is planned with you and carried out by your own team or a qualified partner. Deliverables are for research use only and are not intended for diagnostic or therapeutic use.
Is This the Right Service for You?
Choose this when
A precise sequence change, tag or cassette must be introduced at the native locus
A patient variant needs modelling in an isogenic background
Endogenous regulation must be preserved rather than replaced by a transgene
Consider another service when
Simple disruption of the gene is sufficient
Stable Knockout Cell Line Design Expression from a separate cassette is acceptable
Gene Expression Cell Line Design What Goes Wrong, and How We Handle It
These are the failure modes that produce confident-looking results which do not survive the next experiment. Each one is designed against rather than discovered afterwards.
A cut site too far from the intended edit
Guide selection weights proximity to the edit as heavily as predicted activity, because efficiency falls sharply with distance.
The corrected allele being cut again
Silent mutations in the PAM or seed region are designed into the donor so a successful edit is not re-targeted.
Random integrants mistaken for correct knock-ins
Junction PCR and copy number assays are designed alongside the donor so the two can be distinguished.
A Worked Example
Tagging an endogenous protein without disturbing it
The situation
The team needed a fluorescent tag at the native locus but the protein had a C-terminal localisation signal.
What the work involved
Both termini were modelled for folding and signal interference, donor arms were designed for the chosen format, and silent changes were planned to prevent re-cutting.
What came back
N-terminal tagging was recommended with a flexible linker, and the C-terminal option was shown to mask the localisation motif. Screening primers and a copy number assay were delivered with the donor.
Illustrative of the shape this work takes. Details are generalised, no client or target is identified, and scope and outcome vary with the system in question.
Service Workflow
1
Scientific Consultation
We discuss the objective, the decision it supports and the material and data you already hold.
2
Feasibility Review
We check that the target, system and available information can support the approach, and say plainly where they cannot.
3
Technical Proposal
Scope, methods, deliverables, timeline and price are confirmed in writing, together with the limitations we expect to report.
4
Design and Analysis
The design work runs on documented tools and parameters, with quality checks and alternatives compared where that is informative.
5
Delivery and Follow-Up
You receive the designs, the supporting analysis and a validation plan, plus support interpreting the results once the experiments run.
Service Process
1
Online Consultation
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2
Solution Matching
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3
Service Contract
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4
Project Execution
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5
Data Delivery
Specifications & Turnaround
Note: ICDMO delivers computational (in silico) services. Results prioritise hypotheses for testing; they do not by themselves establish binding, biological activity, efficacy or safety. All deliverables are for research use only and are not intended for diagnostic or therapeutic use. Downstream experimental work is scoped separately and executed through qualified partners.
Get a Custom Quote
Our scientific team responds within 24 hours with a detailed technical proposal and pricing tailored to your project.
Contact Us Online ConsultationStandard Deliverables
✓Sequence-verified final product
✓Full QC documentation
✓Certificate of Analysis (CoA)
✓Electronic data files
✓Project completion report
Why ICDMO?
Computational CDMO Focus
Reproducible, Versioned Pipelines
Confidence & Limitations Reported
Experiment-Aware Recommendations
Response Within One Business Day