Knowing whether a cell is alive is no longer a sufficient quality measure in the manufacturing of cellular therapies. Traditional viability assays have long provided a fast and familiar way to determine whether cells meet a basic live or dead threshold, but those assays do not fully describe whether living cells are healthy, functional, resilient, or ready to perform in a manufacturing process.
This distinction is especially important for cell therapies, where the cell is not simply a component of the product, it is the therapy. A viable cell may still be stressed, functionally impaired, poorly responsive to activation, less capable of expansion, or unlikely to deliver the desired therapeutic effect. In these cases, a culture can appear acceptable by conventional viability criteria while still carrying risks that affect yield, potency, consistency, or patient access.
This is why the cell therapy field needs a broader way to assess living cells. Cell viability can be defined as the measurable state or proportion of cells in a sample that meet defined criteria for being alive, commonly based on indicators such as membrane integrity, dye uptake or exclusion, or the absence of markers associated with cell death. Viability tells cell therapy manufacturers whether cells meet a minimum survival threshold. Cell vitality, in contrast, can be defined as the multidimensional state of a living cell that reflects not only survival, but also its capacity to respond, recover, expand, differentiate, and perform its intended biological function. Vitality helps assess whether those cells are still on a path toward successful performance.
The Gap Between Viability and Vitality
The limitation of traditional viability is not that it lacks value, it’s that it answers a narrow question. Traditional assays can confirm whether cells meet conventional viability criteria, but living-cell products engineered to perform complex biological functions require more than survival. Manufacturing teams need to know whether donor or patient cells are likely to expand, whether activated cells are responding appropriately, whether differentiating cells are maintaining the desired trajectory, and whether cells in the final product remain functionally poised for administration. None of these questions are answered by a single live/dead value.
For practical reasons, cell viability readouts have long been used as surrogates for cellular function, including in vivo performance or engraftment potential. However, studies of CD34+ hematopoietic stem cell transplants have shown that post-thaw viability does not always predict functional activity or engraftment behavior. Early stress, activation failure, or functional impairment may appear before a cell is classified as nonviable.
This is where vitality provides a more complete view of cellular condition. Vitality captures the idea that cells exist along a continuum, from robust and functional to stressed and compromised. A culture may show high overall viability while containing subpopulations that are less responsive, less potent, or more vulnerable to process stress. Measuring vitality gives developers a way to detect these shifts earlier, before they appear as failed release criteria, reduced yield, or poor process performance.
Why Vitality Matters Across Cell Therapy Manufacturing
Vitality matters because every stage of cell therapy manufacturing depends on cellular condition. At the starting material stage, patient- or donor-derived cells can vary widely before manufacturing begins. Two samples may show similar viability but differ in activation potential, stress state, or ability to expand. These differences can influence whether a manufacturing run begins with strong biological input or hidden risk.
During expansion, subtle changes in cell state can affect growth rate, population composition, and yield. A culture may remain largely viable while drifting away from the characteristics needed for a consistent final product. Vitality measurements can help reveal whether cells are maintaining the functional state required for successful therapy production.
During activation, modification, or transduction, compromised cells may respond differently to stimulation or gene delivery. They may survive the process but perform less effectively. In differentiation workflows, early shifts in cell state may influence lineage commitment or final phenotype. At the final product stage, cells may meet a minimum viability specification while still differing in readiness, robustness, or functional potential.
These examples all point to the same conclusion. When cells are the therapy, quality cannot be understood through survival alone. A wider view of the state of cellular function is needed to support consistency across donors, batches, scales, and manufacturing sites.
Why ISO 8934-1:2026 Matters
The publication of ISO 8934-1:2026 reflects the growing importance of fit-for-purpose cell viability measurement. The standard provides general requirements and considerations for cell viability analytical methods, including method selection, reporting, standard operating procedures, and management of variability across pre-analytical, analytical, and post-analytical phases. This is important because cell viability data are used to support decisions across development and manufacturing. Viability measurements may inform starting material qualification, process monitoring, comparability, lot release, product stability, and technology transfer. If those measurements vary across laboratories, platforms, operators, or sites, the resulting data can become difficult to interpret. Standardization helps establish a more consistent framework for how cell viability methods are selected, performed, and reported.
The broader significance of ISO 8934-1:2026 is that it reinforces the need to choose the right analytical method for the biological question being asked. In cell therapy manufacturing, the question is rarely limited to whether cells are alive. More often, the relevant question is whether cells are healthy enough, functional enough, and consistent enough to support the next step in the process. That is where the conversation begins to shift from viability to vitality.
How LumaCyte Supports a More Functional View of Cell State
LumaCyte’s Radiance platform, powered by Laser Force Cytology (LFC), supports the shift from viability to vitality by measuring living cells in a label-free, single-cell format. Instead of relying on dyes, stains, antibodies, or destructive preparation, LFC measures intrinsic biochemical and biophysical properties of individual cells. This allows developers to assess the real-time state of cells while preserving the living sample. Cells do not need to be forced into a simplified live/dead category before they can be evaluated.
With LFC, each cell contributes quantitative information about its condition. The resulting data can reveal subtle differences in cellular response, stress, activation, differentiation, or decline of the entire culture that may not be captured by traditional viability assays alone. Radiance enables manufacturers to move from a static viability check toward a more dynamic assessment of cell performance potential. In practical terms, this means developers can evaluate whether cells are not only alive, but strong enough to continue through manufacturing and perform as intended.
LumaCyte’s inclusion in ISO 8934-1:2026 is important because it places this type of precision, label-free cellular assessment within the broader movement toward standardized, fit-for-purpose cell viability measurement. It also reflects a growing recognition that living-cell products require measurements that assess more than simply surviving. Vitality provides a broader analytical framework for understanding the living state of cells used in modern therapies.
From Better Measurement to Better Decisions
Better vitality measurements give manufacturing teams more than just additional data, they provide a stronger basis for action. When early changes in cell state are visible, teams can adjust culture conditions, evaluate process timing, compare starting material quality, or investigate sources of variability before final product quality is affected. This has direct implications for process development and scale-up. More informative cell-state data can help developers identify which process conditions support stronger performance and which introduce risk. It can also support comparability assessments by showing whether cells remain functionally consistent after process changes, equipment changes, or site transfers.
Vitality data may also support more confident release strategies over time. As cell therapies move toward commercial manufacturing, developers need analytical approaches that can help reduce uncertainty without adding unnecessary complexity. A more precise and standardized view of cellular state can strengthen process understanding and support better decisions across the product lifecycle.
The Next Standard for Living Cells
The field is moving beyond simple live/dead measurements because living therapies demand more from their analytics. Viability remains important, but it is no longer sufficient on its own. Developers need to understand whether cells are capable of performing the biological functions that define product quality.
ISO 8934-1:2026 signals a broader movement toward more rigorous, fit-for-purpose assessment of mammalian cell viability, and that movement aligns with the need for more informative ways to understand living cells. By supporting a vitality-focused view of cellular state, LumaCyte is helping shift the industry toward measurements that better reflect how cells behave, respond, and perform.
For cell therapy developers, moving beyond simple viability measurements is essential to better understanding and controlling cellular performance. Vitality measurements can support stronger starting material decisions, more consistent manufacturing, improved comparability, and greater confidence in the final product.
Learn how LumaCyte’s Radiance platform supports label-free, real-time assessment of cell vitality across advanced therapy manufacturing at LumaCyte.com.
- ISO 8934-1:2026 – Biotechnology — Cell viability analytical methods — Part 1: General requirements and considerations
- Second Global ISO Standard Expands LumaCyte Measurement Framework to Mammalian Cell Viability
- The Hidden Flaw in Living Drugs and the New Standard to Fix It – BriefGlance.com
- Post-thaw viability of cryopreserved peripheral blood stem cells (PBSC) does not guarantee functional activity: important implications for quality assurance of stem cell transplant programmes – PubMed
- Autologous transplantation: the viable transplanted CD34+ cell dose measured post-thaw does not predict engraftment kinetics better than the total CD34+ cell dose measured pre-freeze in patients that receive more than 2 × 106 CD34+ cells/kg – ScienceDirect
