CD Biosynsis offers high-precision Mammalian Cells Gene Knock-in Services, utilizing CRISPR-Cas9 coupled with Homology-Directed Repair (HDR) to achieve stable, site-specific integration of exogenous DNA into host genomes like CHO (Chinese Hamster Ovary) cells and HEK293 cells. Gene knock-in is the gold standard for creating commercial cell lines and advanced research models, as it ensures the therapeutic gene (e.g., monoclonal antibodies (mAbs), fusion proteins) or reporter cassette is integrated into a verified genomic safe harbor locus (e.g., AAVS1, ROSA26). This approach eliminates the variability and silencing associated with random integration (transfection), guaranteeing stable, high-level, and homogeneous expression of the target protein across the entire production run. We provide end-to-end service, from donor design and optimization to final clone verification, resulting in a robust, regulatory-friendly Master Cell Bank (MCB).
Get a QuoteStable gene expression is paramount in biomanufacturing. Unlike random integration, which is susceptible to positional effects and gene silencing, our CRISPR-Cas9/HDR platform ensures the gene of interest (GOI) is integrated precisely at a pre-validated, transcriptionally active genomic site (Knock-in). This process involves Cas9 inducing a double-strand break (DSB) at the target locus, which is repaired via the highly accurate Homology-Directed Repair (HDR) pathway, utilizing a donor template that contains the GOI flanked by homology arms. This strategy is essential for achieving the required clonal homogeneity and long-term stability for regulatory approval.
Safe Harbor Targeting
Targeting validated genomic safe harbor loci (e.g., CHO-specific loci) known for high, stable, and constitutive gene expression to prevent silencing and maximize specific productivity (Qp).
Donor Template Optimization
Design of the HDR donor plasmid/DNA template, including optimized homology arms, promoter/enhancer elements, and selection markers, to maximize HDR efficiency and expression levels.
Dual Allele Knock-in
Strategy for integrating the therapeutic gene into both alleles of the target locus (where applicable) to further double the gene copy number and boost expression titer.
CRISPR-Cas9 & gRNA
Use of highly active Cas9 and validated gRNAs to maximize the double-strand break rate, which is the limiting step for subsequent HDR-mediated knock-in.
RNP + Donor Delivery
Co-delivery of the RNP (Cas9 protein + gRNA) and the linear donor DNA template via optimized electroporation protocols to maximize transient expression and HDR rate.
HDR Enhancer Use
Application of chemical or molecular HDR enhancers to temporarily suppress the competing NHEJ pathway, increasing the final yield of successful knock-in clones.
Therapeutic Gene Integration
Stable knock-in of expression cassettes for monoclonal antibodies (mAbs), fusion proteins, or biosimilars into manufacturing host cell lines (CHO, HEK293).
Reporter Gene Integration
Insertion of fluorescent proteins (e.g., GFP, mCherry) or luminescence reporters at specific genomic sites for non-invasive tracking or high-throughput screening assays.
Precision Disease Modeling
Introduction of precise single nucleotide changes (SNPs) or disease-causing mutations into isogenic cell lines (e.g., iPSCs, primary cells) for advanced functional genomics studies.
A precision-guided process for stable genomic integration and clonal verification.
1. Donor & gRNA Design
2. RNP & Donor Co-Delivery
3. Single Cell Cloning & Screening
4. Clone Verification & MCB Delivery
Select the optimal genomic safe harbor locus for the host cell (CHO/HEK).
Design high-specificity gRNA(s) targeting the locus and synthesize the HDR donor cassette with optimized homology arms and regulatory elements.
Design junction PCR primers to confirm accurate site-specific integration.
Deliver the RNP complex (Cas9 + gRNA) and the donor template into the mammalian host line using optimized transfection/electroporation.
Culture cells in a high-HDR-rate medium with chemical enhancers.
Apply antibiotic selection or FACS sorting to enrich for cells that have successfully integrated the cassette.
Genotype verification via junction PCR and definitive sequencing across the integration site to confirm clean, precise insertion (no random integration).
Phenotypic validation of the final clone for stable expression and product functionality over long passages.
Delivery of the verified Master Cell Bank (MCB) and comprehensive documentation.
Guaranteed Stable Expression
Integration into genomic safe harbor loci ensures robust, consistent, and long-term stable expression, essential for commercial manufacturing and regulatory compliance.
High Clonal Homogeneity
Site-specific integration ensures all producer cells have the identical genetic modification at the same optimal location, minimizing clone-to-clone variability.
Maximized Production Titer
By placing the gene cassette into a transcriptionally "hot" locus, we maximize the specific productivity (Qp) and final volumetric titer of the biotherapeutic.
Precision Research Models
Ideal for creating highly controlled, isogenic cell lines and reporter lines where the exact copy number and genomic context of the inserted gene are critical.
1. What is a "Genomic Safe Harbor Locus" and why is it used?
A genomic safe harbor locus is a pre-validated genomic region that is transcriptionally active but where integration does not disrupt any essential host gene. Using it ensures stable, high expression and is critical for regulatory approval by avoiding random integration (positional effects).
2. What size of DNA fragment can you knock in?
While the efficiency of HDR decreases with size, our optimized protocols routinely achieve successful knock-in of cassettes up to 5 kb, which is sufficient for most therapeutic gene expression constructs (including mAbs and large fusion proteins).
3. How do you verify site-specific integration?
Verification is done via junction PCR and subsequent sequencing. Primers are designed to span the junction between the host genome and the newly integrated donor DNA, confirming the precise insertion site and ruling out off-target or random integration.
4. What is the role of HDR enhancers?
HDR (Homology-Directed Repair) is typically inefficient compared to the competing NHEJ pathway. Enhancers are chemical compounds or molecular factors that temporarily suppress NHEJ or promote HDR, significantly increasing the yield of desired knock-in clones.
5. What input is required for a Gene Knock-in project?
We require the specific mammalian host cell line (e.g., CHO, HEK293) and the sequence of the therapeutic or reporter gene (GOI) along with the desired integration site (if known, or we can recommend a safe harbor locus).
6. Can you achieve dual allele knock-in?
Yes. For select genes with two functional alleles in the host genome, we can enrich for clones where the cassette has been successfully integrated into both alleles, effectively doubling the gene copy number and boosting production titer.
7. How does this service improve commercial cell line development?
It replaces the traditional, time-consuming random integration/amplification method (e.g., DHFR/GS) with a rapid, site-specific process that yields clones with inherently higher stability and clonal homogeneity, significantly accelerating the Master Cell Bank (MCB) timeline.
8. What is the difference between Gene Knock-in and Gene Knockout?
Gene Knock-in is the process of precisely inserting a new gene sequence into the genome (using HDR). Gene Knockout is the process of disrupting or deleting a native gene (using NHEJ) to eliminate its function.
CRISPR-Cas9 technology represents a transformative advancement in gene editing techniques. The main function of the system is to precisely cut DNA sequences by combining guide RNA (gRNA) with the Cas9 protein. This technology became a mainstream genome editing tool quickly after its 2012 introduction because of its efficient, simple and low-cost nature.
The CRISPR gene editing system with its Cas9 version stands as a vital instrument for current biological research. CRISPR technology enables gene knockout (KO) through permanent gene expression blockage achieved by sequence disruption. Various scientific domains including disease modeling and drug screening employ this technology to study gene functions. CRISPR KO technology demonstrates high efficiency and precision but requires confirmation and verification post-implementation because unsatisfactory editing may produce off-target effects or incomplete gene knockouts which impact experimental result reliability. For precise and efficient Gene Editing Services - CD Biosynsis, Biosynsis offers comprehensive solutions tailored to your research needs.
The CRISPR-Cas9 knockout cell line was developed using CRISPR/Cas9 gene editing to allow scientists to remove genes accurately for research on gene function and disease models and pharmaceutical discovery. Genetic research considers this technology essential due to its high efficiency together with simple operation and broad usability.
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CD Biosynsis is a leading customer-focused biotechnology company dedicated to providing high-quality products, comprehensive service packages, and tailored solutions to support and facilitate the applications of synthetic biology in a wide range of areas.