Plasmid DNA is a core starting material for cell and gene therapy (CGT) and serves as the IVT template for mRNA vaccines and therapeutics. Plasmid quality directly determines the safety and efficacy of the final therapeutic product.
A common root cause of IND filing delays or manufacturing failures is the absence of proper plasmid release testing. Creative Biogene has restructured plasmid release testing into a system centered on "risk identification – regulatory interpretation – method validation – submission readiness." Based on a deep understanding of regulatory CMC guidance, ICH Q5 series, USP chapters, and BioPhorum consensus, we offer a full-spectrum release program that follows cGMP principles.
The most easily overlooked risks for plasmid as a CGT starting material include:
(1) Sequence variants — NGS detection of low-frequency variants (≥1% VAF) may be introduced early in cell line development and accumulate during scale-up;
(2) Supercoil percentage fluctuations — directly affect transfection efficiency and mRNA IVT yield, thereby influencing final product potency;
(3) Hidden impurities — such as low-abundance HCP and HCD residues not covered by ELISA, which may pose immunogenicity risks.
| Project Stage | Typical Strategic Focus | Commonly Included Testing Items (example) |
| Early R&D / Process development (clone screening, transfection optimization, process parameters) | Rapid Release | ddPCR copy number, automated CE for supercoil %, rapid endotoxin. Optimized for turnaround to support rapid decisions. |
| Pre-IND submission (data integrity, regulatory compliance, method validation) | Advanced Release | NGS full plasmid sequencing, ddPCR precise copy number, LC-MS/MS HCP characterization, stability studies (ICH Q5C), transcription suitability. Designed for IND submission batches and GMP-aligned release. |
| Commercial manufacturing (long-term stability, batch-to-batch consistency, supply chain reliability) | Core Release | Sanger identity, A260/280 concentration/purity, supercoil % (HPLC/CE), residual RNA, residual host DNA (qPCR), residual host protein (ELISA), residual antibiotics, endotoxin, bioburden, appearance, pH. Suitable for research-grade release and early process development. |
For Rapid Release: longer lead-time tests may be performed as subsequent supplemental data to balance timeliness and compliance.
| Test Item | Core | Advanced | Rapid |
| Plasmid identity (Sanger full sequence) | ✓ | ✓ | ✓ |
| Plasmid identity (NGS full sequence) | — | ✓ | — |
| Plasmid concentration (A260/280) | ✓ | ✓ | ✓ |
| Supercoil % (HPLC/CE) | ✓ | ✓ | ✓ |
| Residual RNA (fluorometric) | ✓ | ✓ | ✓ |
| Residual host DNA (qPCR/ddPCR) | ✓ (qPCR) | ✓ (ddPCR) | ✓ (qPCR) |
| Residual host protein (ELISA) | ✓ | ✓ | ✓ |
| Residual host protein (LC-MS/MS) | — | ✓ | — |
| Residual antibiotics | ✓ | ✓ | ✓ |
| Endotoxin (USP <85>) | ✓ | ✓ | ✓ (rapid) |
| Bioburden (USP <61>) | ✓ | ✓ | ✓ |
| Sterility (USP <71>) | upon request | upon request | upon request |
| Appearance/pH | ✓ | ✓ | ✓ |
| Plasmid copy number (ddPCR) | — | ✓ | ✓ |
| Stability studies (ICH Q5C) | — | ✓ | — |
| Transcription suitability | — | upon request | — |
| Host gDNA residue | — | ✓ | — |
Regulatory compliance framework
Based on ICH Q5A/Q5B/Q5C/Q6B and USP chapters. We operate in accordance with GLP and cGMP principles. Data management follows ALCOA+, LIMS provides full traceability, and independent QA reviews each batch.
Method validation and orthogonal strategies
Compendial methods (USP <61>/<71>/<85>, USP <791>/<790>) are qualified per pharmacopoeia; non-compendial methods (NGS full-plasmid sequencing, ddPCR, LC-MS/MS HCP profiling) are validated per ICH Q2(R2). We use an ELISA + LC-MS/MS orthogonal strategy for HCP to avoid blind spots.
Stage-adapted testing strategy
Core package for early development; Advanced package adds NGS, LC-MS/MS HCP characterization, and ICH Q5C stability; Commercial stage adds enhanced stability and batch consistency.
Submission-ready data delivery
Reports designed for IND/BLA submission, including method validation summaries, raw data, compliance statements, and acceptance criteria justifications.
| Platform | Key Instruments / Capabilities | Description |
| Sequencing | Illumina MiSeq / NextSeq (NGS), Applied Biosystems SeqStudio (Sanger) | Sanger full plasmid sequencing for routine release; NGS for low-frequency variants, host/microbial DNA screening, and repetitive regions (ITRs) |
| Molecular Biology | QuantStudio qPCR, Bio-Rad QX200 ddPCR | Absolute plasmid copy number, HCD quantification, RCL/RCR screening; ddPCR ideal for complex samples |
| Chromatography & Electrophoresis | Agilent 1260 HPLC, SCIEX PA 800 Plus CE | Supercoil percentage (HPLC/CE), impurity separation (SEC, RP-HPLC), RNA residues |
| Mass Spectrometry | Agilent 6545XT LC/Q-TOF | HCP identification/quantification (LC-MS/MS), capping efficiency, polyA tail distribution |
| Microbiology | BSC, multi-zone incubators, automated colony counter, LAL system | Bioburden, sterility, endotoxin, aerobic/anaerobic/microaerophilic |
Full sequence verification of key functional elements (T7, ITR, CAR, etc.) for library construction and batch release.
Precise quantification and trend monitoring for process development and stability studies.
Assessment of supercoil percentage and plasmid retention for long-term and accelerated stability studies.
Detection of RNA residues after purification.
Meets GMP-aligned plasmid release requirements for transfection or in vivo applications.
Quantification of host cell protein residuals, mandatory for plasmids used in downstream manufacturing.
Quantitation of host cell gDNA residuals.
Microbial enumeration for non-sterile starting materials, applicable to GMP-aligned plasmid release.
Evaluates IVT efficiency, capping rate, and polyA tail distribution when the plasmid serves as an mRNA template.
Plasmid release testing is critical for CGT and mRNA drug CMC strategy. If you are preparing a release plan or have uncertainties about pre-IND testing, now is the time to front-load risks. We will design a strategy based on your project stage, plasmid type, and final application — ensuring robust data from the source. Contact us today for a customized plan and quote.
Q1: Differences between GMP-aligned grade and research-grade plasmid release?
A: GMP-aligned grade follows cGMP principles with comprehensive testing (full identity, quantitative impurities, bioburden/sterility, stability, full documentation). Research grade focuses on core attributes (identity, purity, concentration, endotoxin). EMA 2021 guidance states that the plasmid for ATMP manufacturing should follow GMP principles.
Q2: How much sample is required?
A: Typically 20-50 µg (Core) or 50-100 µg (Advanced). Contact us for a detailed sample requirement sheet.
Q3: Sanger vs. NGS sequencing for plasmid release?
A: Sanger is standard for routine release. BioPhorum notes that Sanger struggles with repetitive regions (ITR/LTR, polyA) — NGS should be used. NGS detects low-frequency variants (≥1% VAF), screens for host/microbial DNA, and covers complex regions. Core: Sanger; Advanced: NGS (especially for IND submission or plasmids with repetitive structures).
Q4: Why is supercoil % important? How to set acceptance criteria?
A: A supercoiled plasmid is the most bioactive form. It affects transfection efficiency and mRNA IVT yield/quality. Industry benchmark: >80% supercoiled is "high quality"; GMP-aligned grade often requires ≥90%. We help establish risk-based acceptance criteria.
Q5: How to ensure data acceptance by regulatory authorities?
A: Three aspects: (1) Method compliance — compendial methods qualified, non-compendial validated per ICH Q2(R2) with bridging data. (2) Acceptance criteria justification — based on product, phase, and risk. (3) Complete data package — validation summaries, raw data, compliance statements, standard traceability. Our reports are IND/BLA-ready for direct CMC module inclusion.
Copyright © 2026 Creative Biogene. All rights reserved.