Karyotype Analysis

Karyotype Analysis

1. Background

Chromosomal karyotype analysis is a key quality control testing item for cell therapy products, used to assess the genetic stability of cells. The Chinese Pharmacopoeia (2025 Edition), which officially came into effect on October 1, 2025, has introduced more rigorous scientific requirements for karyotype analysis of human diploid cell banks.

The core updates to the new Pharmacopoeia edition include:

(1) Optimization of the number of cells to be examined: the requirement for metaphase cell examination has been revised from 1,000 and 500 or more cells to a precise count of 200 or more metaphase cells;

(2) Standardization of abnormality description: supplementary specific descriptions for chromosomal structural abnormalities are required; in cases where non-diploid chromosomal abnormalities are identified during the precise count, a further detailed karyotype analysis must be performed;

(3) Clearer standards: a chromosomal analysis standard based on 200 metaphase cells has been established.

ZhuHai GeneRulor strictly adheres to the latest Pharmacopoeia requirements, providing professional chromosomal karyotype analysis services for CAR-T cells, stem cells, vaccine production cells, and other cell types, facilitating safety evaluation and IND/NDA submissions for cell therapy products.

2. Technical Principle of G-Banding Karyotype Analysis

G-banding karyotyping is the international gold standard method for chromosome analysis. This technique achieves precise chromosome analysis through the following steps:

Technical Principle:

(1) Mitotic stimulation and arrest: cells are induced to enter mitosis and treated with colchicine to arrest them at metaphase, at which point chromosomes are most condensed and optimally suited for analysis;

(2) Hypotonic treatment: cells are swollen to allow chromosomes to fully disperse;

(3) Fixation and slide preparation: cytoplasm is removed while preserving chromosome morphology;

(4) G-banding staining: following trypsin digestion and Giemsa staining, a distinctive light-and-dark banding pattern specific to each chromosome is revealed;

(5) Microscopic analysis: light microscopy and karyotype analysis software are used to precisely identify numerical abnormalities (hyperdiploidy, hypodiploidy, polyploidy) and structural abnormalities (deletions, translocations, inversions, etc.).

Detection Resolution:

300–400 band resolution, capable of detecting subtle chromosomal structural changes.

Result Interpretation:

Karyotype nomenclature and interpretation follow the ISCN 2020 (International System for Human Cytogenomic Nomenclature) standard.

Figure 1. G-banding karyotype analysis technical workflow

3. Technical Advantages and Quality Assurance

3.1 Multi-Tier Detection Plans to Meet Diverse Needs

Standard Plan (Recommended):

(1) Analysis of 200 metaphase cells; strictly compliant with the latest requirements of the 2025 Pharmacopoeia;

(2) Applicable to IND/NDA submissions, clinical sample testing, and commercial production quality control.

Enhanced Plan:

(1) Analysis of 500 or 1,000 metaphase cells;

(2) Applicable to requirements for higher statistical rigor, rare anomaly detection, and key quality research.

Rapid Plan:

(1) Analysis of 100 metaphase cells;

(2) Applicable to early-stage R&D, process exploration, and preliminary evaluation.

All plans comply with Pharmacopoeia requirements. Karyograms are prepared and documented in detail for all cells with detected chromosomal abnormalities. Standardized abnormality rate statistics are provided (hyperdiploidy, hypodiploidy, polyploidy, structural abnormalities, etc.). ISCN 2020 international standard nomenclature is adopted throughout.

3.2 Comprehensive Quality Management System

(1) ISO 9001 quality management system certification;

(2) CNAS laboratory accreditation; CAP certification in progress;

(3) Three-level review system: self-review by the laboratory technician, review by the karyotype analyst, and final approval by an authorized signatory;

(4) Complete data traceability: microscopic images archived for 1 year; karyograms archived for 6 months; experimental records archived for 1 year.

3.3 Professional Technical Team

(1) All testing personnel hold relevant professional qualification certificates;

(2) Regular participation in professional training to ensure the accuracy and reliability of testing results;

(3) Extensive experience in testing cell therapy products.

4. Application Scenarios

The chromosomal karyotype analysis service of ZhuHai GeneRulor is broadly applicable to:

4.1 CAR-T Cell Product Quality Control

(1) Chromosomal stability assessment of post-gene-editing cells;

(2) Hereditary safety testing of multi-site knockout CAR-T cells;

(3) Chromosomal stability monitoring across different generations of cells.

4.2 Stem Cell Product Quality Evaluation

(1) Karyotype monitoring during iPSC/ESC passaging;

(2) Chromosomal stability assessment before and after differentiation;

(3) Quality release testing of clinical-grade stem cells.

4.3 Cell Substrate Quality Control for Vaccine Production

(1) Cell bank establishment and characterization;

(2) Passage stability assessment;

(3) Periodic testing compliant with Pharmacopoeia requirements.

4.4 IND/NDA Submission Support

(1) Provision of testing reports compliant with CDE (Center for Drug Evaluation) and FDA requirements;

(2) Support for pharmacological study and quality control documentation;

(3) Chromosomal stability data support for preclinical and clinical stages.

4.5 Scientific Research Project Support

(1) Safety assessment of gene-editing tools;

(2) Cell line hereditary stability research;

(3) Chromosomal variation research in tumor cells.

5. Representative Karyotype Analysis Detection Report

GeneRulor provides comprehensive and professionally structured chromosomal karyotype analysis reports in full compliance with regulatory requirements. As illustrated, the report encompasses complete sample traceability information (including sample name, sample type, specimen characteristics, purpose of submission, submitted by, and date of submission), high-resolution G-banding karyotype images, ISCN-compliant karyotype nomenclature, and a professional karyotype description that systematically addresses the total number of cells analyzed, the number of cells suitable for analysis, banding quality, and the presence or absence of numerical and structural chromosomal abnormalities. In addition, the report includes a Chromosome Count Analysis Record Table
and a Chromosome Count Analysis Summary Table: the former documents the image number and corresponding karyotype result for each analyzable cell, ensuring full data traceability; the latter summarizes the frequencies of various abnormality categories — including chromatid and chromosome breaks, structural abnormalities, hyperdiploidy, hypodiploidy, and polyploidy — against the pharmacopeial upper limits, providing a clear and quantitative assessment of chromosomal stability for the sample.

Figure 2. Representative Chromosomal Karyotype Analysis Report generated by GeneRulor

6. Service Content and Workflow

* Standard service turnaround: 10–15 business days (counted from the date qualified samples pass QC upon receipt).

* Optional plans: customized plans of 100/200/500/1,000-cell analysis available based on client requirements; detection depth and turnaround adjusted accordingly.

* Value-added services: IND submission technical consultation and documentation support available; PEM-seq chromosomal rearrangement refined analysis service available.

7. Sample Submission Guide and Requirements

7.1 Detection Plan Selection Guidance

Clients may select an appropriate detection plan based on their stage of research:

(1) Early-stage R&D (cell line establishment, initial process exploration): the 100-cell rapid plan is available for quick evaluation;

(2) Process development stage (process optimization, pilot scale-up): the 200-cell standard plan is recommended;

(3) Clinical submission stage (IND/NDA preparation): the 200-cell standard plan compliant with the 2025 Pharmacopoeia must be adopted;

(4) Special research needs (rare anomaly detection, high statistical requirement): the 500/1,000-cell enhanced plan is available;

(5) Commercial production stage (batch release, routine monitoring): the 200-cell standard plan is recommended;

(6) The ZhuHai GeneRulor technical team can provide professional recommendations based on the client's specific needs.

7.2 Sample Types and Acceptance Standards

Karyotype analysis requires a sufficient number of viable, dividing cells. To ensure acquisition of enough analyzable metaphase spreads, it is recommended to provide a total of ≥1–2×10⁶ viable cells (accounting for cell loss during culture, mitotic stimulation, and slide preparation). The ZhuHai GeneRulor laboratory can accept the following four sample types:

7.2.1 Cryopreserved Cells (Most Common):

(1) Sample volume: ≥2–3 cryovials per sample (each vial ≥1×10⁶ cells); a spare vial is recommended;

(2) Cryopreservation medium: standard freezing medium (10% DMSO);

(3) Viability requirement: post-thaw viability ≥70%;

(4) Shipping conditions: dry ice, maintaining a cold chain throughout;

(5) Note: detailed cell culture conditions (culture medium type, growth factors, special supplements, etc.) must be provided.

7.2.2 Fresh Cell Suspension (Suitable only for delivery within 1–2 days; long-distance shipping not recommended):

(1) Suspension cells: total cell count ≥7.5×10⁶ cells; aliquoted into 3 × 25 cm² culture flasks; density approximately 0.5×10⁶ cells/mL; culture medium ≥5 mL per flask;

(2) Adherent cells: 3 × 25 cm² culture flasks; cell confluence 30–40% per flask; culture medium ≥5 mL per flask;

(3) Shipping requirements:

• Fill culture flasks fully with medium to avoid air bubbles;

• Attach sample information label to the side of the flask;

• Above 20°C: ship at 4°C cold chain;

• 0°C to 20°C: ship at ambient temperature;

• Below 0°C: ship with insulated packaging;

(4) Time requirement: deliver within 1–2 days of collection.

7.2.3 Fixed Cell Suspension (Requires client to have pre-processing capability):

(1) Client pre-processing protocol (brief):

• Culture cells to logarithmic growth phase;

• Add colchicine (final concentration 0.1–0.2 μg/mL) to arrest cells for 2–3 hours;

• Harvest cells; hypotonic treatment with 0.075 M KCl (37°C, 8–20 minutes);

• Carnoy's fixative (3:1) fixation ×3, 20 minutes each;

• Resuspend fixed cell pellet in 1.5–2 mL of fixative and transfer to a screw-cap tube;

(2) ZhuHai GeneRulor can provide detailed cell fixation protocols and technical guidance;

(3) Package according to hazardous material shipping regulations (fixative is flammable); ship in an ice bag.

7.2.4 Pre-Prepared Slides (Requires client to have professional slide preparation capability):

(1) Sample condition: fixed metaphase spread slides, either unstained or with G-banding already performed;

(2) Quality requirements: metaphase spreads must be round and intact, well-dispersed, non-overlapping, with clean background and no cellular debris accumulation;

(3) Sample quantity: at least 3–5 slides per sample to ensure sufficient analyzable metaphase cells (≥200 metaphase spreads required for analysis);

(4) Labeling: sample number labeled on the frosted end of the slide in pencil (marker pens are prohibited);

(5) Packaging and shipping: slides placed in a slide box or dedicated slide rack; separated by filter paper; outer packaging labeled "Fragile"; shipped at ambient temperature.

ZhuHai GeneRulor will perform a quality assessment upon receipt. If samples do not meet testing requirements, the client will be notified promptly and a resolution discussed (adjust culture conditions or re-prepare slides).

7.3 Required Information to Be Provided by Client

When submitting samples, clients must complete the Karyotype Analysis Sample Submission Form and send it together with the samples. The following key information should be provided:

1. Sample type and name;

2. Detection specification (100/200/500/1,000-cell standard);

3. Cell culture conditions (culture medium, serum, growth factors, etc.);

4. Special requirements or notes.

8. References

[1] Chinese Pharmacopoeia (2025 Edition), General Chapter 0234: Preparation and Quality Control of Animal Cells Used in the Production of Biological Products.

[2] ISCN 2020: An International System for Human Cytogenomic Nomenclature (2020).

[3] ICH Q5A(R1): Viral Safety Evaluation of Biotechnology Products Derived from Cell Lines of Human or Animal Origin.

[4] China NMPA. Technical Guidelines for Research and Evaluation of Cell Therapy Products (Trial). 2017.

[5] China NMPA. Key Considerations for Quality Control Testing and Non-Clinical Research of CAR-T Cell Therapy Products.

[6] FDA Guidance for Industry: Characterization and Qualification of Cell Substrates and Other Biological Materials Used in the Production of Viral Vaccines for Infectious Disease Indications.