GMP and Quality by Design: what regulated manufacturing actually requires
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If you are building a tool or platform that will eventually touch a clinical stem cell product, you need to understand what Good Manufacturing Practice (GMP) is and what it requires. Not in abstract terms, but in terms of what it means for how cells are handled, what documentation is expected, what your reagents and materials must look like, and what happens when something goes wrong. This article provides that working understanding.
What GMP is and where it comes from
GMP is a set of principles and requirements governing the manufacture of medicinal products. Its purpose is to ensure that products are consistently produced and controlled to quality standards appropriate for their intended use. GMP applies to every step of production, from starting materials, staffing and facilities through to finished product release, storage, and distribution [1].
For conventional pharmaceuticals, GMP has been codified for decades through national and international regulatory frameworks. The International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) has published a family of quality guidelines that define expectations for pharmaceutical development (ICH Q8), quality risk management (ICH Q9), and pharmaceutical quality systems (ICH Q10), among others [2].
Cell-based products are regulated as Advanced Therapy Medicinal Products (ATMPs) in the European Union and as biological products in the United States. They are subject to the same fundamental GMP principles as other medicines, but the nature of living cells introduces specific challenges that conventional pharmaceutical manufacturing does not face [1,3].
Why cells are different
A conventional drug is a defined chemical entity. Its identity can be confirmed by analytical chemistry. Its stability can be predicted from well-understood physical and chemical properties. Its manufacturing process can be validated by producing a defined number of batches and demonstrating consistency.
Cells are not like this. They are living, variable, and sensitive to their environment in ways that are difficult to predict or fully control. Two batches of the same cell line, processed using the same protocol, can differ in ways that affect their therapeutic function. The starting material, a human tissue sample or a banked cell line, introduces biological variability from the outset. Culture conditions including temperature, media composition, passage method, and even the timing of feeds can influence cell behaviour. Cells can acquire genetic changes during expansion. They can drift in their epigenetic state. They can harbour latent contamination that is not detectable by standard assays [3,4].
This means that GMP for cell products must go beyond following a fixed protocol. It requires a degree of process understanding that allows manufacturers to define which parameters matter, how much they can vary, and what happens to the product when they do.
Quality by Design
This is where Quality by Design (QbD) comes in. QbD is a systematic approach to pharmaceutical development that begins with predefined quality objectives and emphasises understanding the product and process, as well as process control based on science and risk management [2].
The concept originates from ICH Q8 (Pharmaceutical Development) and is supported by ICH Q9 (Quality Risk Management). In practical terms, QbD asks a manufacturer to work through a structured series of steps.
The starting point is a Quality Target Product Profile (QTPP): a description of the desired quality characteristics of the final product, defined in terms of safety, efficacy, and fitness for purpose. For a stem cell therapy, this might include cell viability above a specified threshold, expression of defined markers, absence of contaminants, and demonstrated functional potency [2,5].
From the QTPP, Critical Quality Attributes (CQAs) are identified: the physical, chemical, biological, or microbiological properties that must be within a defined range to ensure product quality. For a pluripotent stem cell product, CQAs might include karyotypic normality, expression of pluripotency markers, and the absence of residual reprogramming vectors [5].
The manufacturing process is then analysed to identify Critical Process Parameters (CPPs) and Critical Material Attributes (CMAs): the specific process conditions and raw material properties that influence CQAs. For cell culture, these might include seeding density, dissolved oxygen, media lot, passage number, and the method and timing of enzymatic dissociation [5,6].
The relationship between CPPs, CMAs, and CQAs is then explored experimentally, often using design of experiments (DoE) approaches, to define a Design Space: the multidimensional range of process conditions within which the product consistently meets its quality specifications. Working within the Design Space is not considered a regulatory change; working outside it is [2].
This is fundamentally different from the traditional approach to pharmaceutical manufacturing, where the process is fixed and validated by demonstrating that a specified number of batches meet specifications. QbD aims for a deeper understanding: if you know how your process parameters affect your product quality, you can adapt and improve the process without starting from scratch.
What this looks like in practice
For stem cell manufacturing, GMP and QbD have specific practical implications.
Facilities must be designed to control contamination risk. Cell processing takes place in cleanrooms or closed systems with defined air quality classifications, restricted access, and environmental monitoring. Equipment must be qualified. Reagents must be of defined grade, ideally GMP-grade or at minimum animal-component-free and traceable to their source [1,3].
Raw materials require particular attention. Culture media, matrix proteins, growth factors, and dissociation enzymes all contact the cells and can influence their properties. Any change to a raw material, including a change by the supplier, can affect the process and must be managed through change control procedures [3].
Documentation is extensive. Every step of the manufacturing process must be recorded in batch records. Deviations from the defined process must be documented, investigated, and assessed for their impact on product quality. Training records, equipment maintenance logs, and environmental monitoring data must be maintained. This documentation is not just administrative overhead. It is the evidence base that allows a manufacturer to demonstrate to regulators that the product was made under controlled conditions and meets its specifications [1].
Quality control testing is performed at defined points: on incoming materials, during the process (in-process controls), and on the finished product (release testing). Release criteria define what the product must look like to be acceptable for clinical use. These criteria are based on the CQAs identified during development and must be backed by validated analytical methods [3,5].
The gap between research and manufacturing
One of the persistent challenges in the field is the distance between a published differentiation protocol and a manufacturing process that can produce a consistent, characterised, and compliant product at the scale needed for clinical use.
Research protocols are typically optimised for scientific discovery, not for manufacturing. They may use materials that are not available in GMP-grade, rely on manual steps that introduce operator variability, or produce cells at a scale that is orders of magnitude below what a clinical trial requires. Translating a protocol from a research laboratory to a GMP facility typically involves re-development of the process with GMP-compatible materials, establishment of in-process controls, development of release assays, and formal process validation [3,6].
From our own experience establishing Scotland's first advanced cell therapy manufacturing capability through Roslin Cells, and subsequently leading the manufacture of quality-controlled iPSC lines for the European Bank for Induced Stem Cells (EBiSC), the translation from research protocol to manufacturing process consistently takes longer, costs more, and reveals more unexpected problems than anticipated. The biology that worked reliably with one operator in one laboratory may behave differently with different operators, different equipment, and different lots of reagents [6,7,8].
This is not a criticism of the research. It is a structural feature of the field. Cell biology is high-dimensional, and the number of variables that can influence outcome is large. QbD provides a framework for managing this complexity, but it requires investment in process understanding that many organisations undertake only when forced to by regulatory requirements.
What this means for tool developers
If you are building ancillary technologies for stem cell workflows, GMP is relevant to you even if your product is not itself a medicine. Reagents, instruments, consumables, and software that are used in the manufacture of cell therapies must be suitable for that purpose. This means defined specifications, traceability, consistency between lots, and documented evidence of performance [3].
The transition from a research tool to a GMP-compatible product is not trivial. It requires formalising specifications, validating performance, establishing supply chain controls, and in many cases redesigning products that were originally built for convenience rather than consistency. Understanding this pathway early, before your product is entrenched in research workflows that cannot translate, is one of the most valuable things a TechBio company can do. The Pillar 2 series examines the broader landscape of why ancillary technologies fail, including articles on reproducibility and scale-up that connect directly to the manufacturing challenges described here.
References
[1] EudraLex Volume 4, Annex 2A: Manufacture of advanced therapy medicinal products for human use. European Commission. 2017.
[2] ICH Q8(R2): Pharmaceutical Development. International Council for Harmonisation. 2009.
[3] Abou-El-Enein M, Romhild A, Kaiser D, et al. Good Manufacturing Practices (GMP) manufacturing of advanced therapy medicinal products: a novel tailored model for optimizing performance and estimating costs. Cytotherapy. 2013;15(3):362-383. DOI: 10.1016/j.jcyt.2012.09.006
[4] De Sousa PA, Renewed assessment of the risk of emergent advanced cell therapies to transmit neuroproteinopathies. Acta Neuropathologica. 2019;137(3):363-377. DOI: 10.1007/s00401-018-1941-9
[5] Lipsitz YY, Timmins NE, Zandstra PW. Quality cell therapy manufacturing by design. Nat Biotechnol. 2016;34(4):393-400. DOI: 10.1038/nbt.3525
[6] De Sousa PA, Downie JM, Tye BJ, Bruce K, Dand P, Dhanjal S, Serhal P, Harper J, Turner M, Bateman M. Development and production of good manufacturing practice grade human embryonic stem cell lines as source material for clinical application. Stem Cell Res. 2016 Sep;17(2):379-390. doi: 10.1016/j.scr.2016.08.011.
[7] De Sousa PA, Steeg R, Kreisel B, Allsopp TE. Hot Start to European Pluripotent Stem Cell Banking. Trends Biotechnol. 2017;35(7):573-576. DOI: 10.1016/j.tibtech.2017.03.004
[8] Steeg R, Mueller SC, Mah N, et al. EBiSC best practice: how to ensure optimal generation, qualification and distribution of iPSC lines. Stem Cell Reports. 2021;16(8):1853-1867. DOI: 10.1016/j.stemcr.2021.07.009
About StemCells.Help
StemCells.Help is an advisory consultancy that aids innovation and real-world impact of life science applications built on developmental and stem cell biology. Founded by Dr Paul De Sousa, it draws on over four decades of experience spanning early embryo development, animal cloning, pluripotent stem cell manufacturing, and technology commercialisation. If you build tools for these domains or work in an emerging application where the biology is the enabling technology, StemCells.Help can provide experienced scientific counsel to ground your decisions. To discuss your needs, talk to Paul.
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