Key Facts about Cell Therapy
Cell therapy is a rapidly expanding pillar of advanced therapy medicinal products (ATMPs), in which living human cells are administered to patients to treat oncological, autoimmune and degenerative diseases, and increasingly also to address global blood supply shortages. Since the first FDA approval of a CAR-T cell therapy in 2017, the field has grown into a clinical reality, with multiple commercial products now in routine use for B-cell malignancies, leukemia, lymphoma and multiple myeloma, while bioreactor-based production of cultured red blood cells and platelets is moving from research into early clinical trials.
Cell therapy products are typically classified as either autologous (using the patient’s own cells) or allogeneic (using donor-derived cells, often as “off-the-shelf” products). Autologous cell therapy minimizes the risk of immune rejection but requires individual cell therapy manufacturing for every patient, leading to long production times of 1–3 weeks and manufacturing failure rates between 2 % and 10 %. Allogeneic cell therapy enables scalable, standardized cell therapy production but must address graft-versus-host disease (GvHD) and host-mediated rejection through genetic engineering of the donor cells.
Therapeutic cells — whether immune effector cells, stem cells, or in vitro generated blood cells — are extremely shear-sensitive, depend on tightly controlled physiological conditions, and undergo complex ex vivo manipulations such as activation, transduction, differentiation and expansion. These properties make controlled cell therapy bioreactors and closed, single-use systems essential for safe and reproducible cell therapy solutions, both in research and in cGMP-compliant clinical production.
Typical cell types used for cell therapy
Cell therapy products cover a broad spectrum of human cell types, each with specific cultivation requirements that influence the choice of cell therapy equipment and bioreactor format.
-
T cells
(CAR-T, TCR-T, TILs)
The most clinically advanced platform. Autologous T cells are isolated from leukapheresis, activated with anti-CD3/anti-CD28 beads, transduced with viral vectors and expanded ex vivo. Approximately 10⁶–10⁷ viable T cells are required for downstream CAR modification, and expansion typically runs over 7–14 days.
-
Natural killer (NK) cells
Increasingly used as allogeneic “off-the-shelf” cell therapy due to a lower risk of GvHD. NK cells can be expanded from peripheral blood, umbilical cord blood or differentiated from iPSCs.
-
Mesenchymal stromal/stem cells (MSCs)
Adherent multipotent cells used for regenerative medicine and immunomodulatory indications such as graft-versus-host disease. MSCs are typically expanded on microcarriers in stirred-tank bioreactors or in hollow-fiber systems.
-
Induced pluripotent stem cells (iPSCs)
A renewable platform for allogeneic cell therapy manufacturing. iPSCs can be reprogrammed, expanded and differentiated into T cells, NK cells, MSCs, cardiomyocytes, neurons, beta cells or erythroid lineages.
-
Hematopoietic stem cells (HSCs) and other immune cells
Used in stem cell transplantation and as starting material for engineered immune cell therapies, including γδ T cells, iNKT and MAIT cells.
-
Cultured red blood cells (cRBCs)
and engineered erythrocytes
Bioreactor-produced red blood cells derived from iPSCs, hematopoietic stem cells or peripheral blood mononuclear cells (PBMCs). In contrast to classical donor-derived transfusion, cRBCs are substantially manipulated ex vivo and therefore classified as ATMPs. Applications include universal O-negative blood products to address chronic supply shortages, transfusion alternatives for patients with rare blood groups, and engineered red blood cells used as drug delivery vehicles for enzymes or therapeutic payloads.
Key process parameters in cell therapy
Therapeutic cells require a tightly controlled environment that mimics physiological conditions. The following critical process parameters (CPPs) are central to every cell therapy manufacturing run, regardless of whether the process is autologous or allogeneic, immune cell expansion or in vitro erythropoiesis, and need to be monitored continuously through PAT-enabled cell therapy systems.
-
Temperature
(36–37 °C)
Maintained within ±0.5 °C of the 37 °C setpoint to preserve cell viability and metabolic activity.
-
pH control
(7.2–7.4)
Regulated via CO₂ sparging or bicarbonate buffering. Deviations affect T cell activation, proliferation, effector function as well as erythroid maturation and enucleation.
-
Dissolved oxygen (DO)
(40–70 %)
Controlled by gas mixing (air/O₂) and gentle agitation. Both hypoxia and hyperoxia impair lymphocyte function, stem cell behavior and erythroid differentiation.
-
Shear stress and agitation
Therapeutic cells are highly shear-sensitive. Low impeller speeds, marine impellers, and bubble size control are used to avoid mechanical damage and apoptosis — particularly relevant for high-density erythroblast cultures up to >30 million cells/mL.
-
Cytokines and growth factors
IL-2, IL-7, IL-15 drive T and NK cell proliferation; SCF, EPO, IL-3 and IL-6 are essential for erythroid expansion and differentiation. Their dosing strategy is a critical quality lever for the final cell therapy product.
-
Metabolite management
Glucose, glutamine, lactate and ammonia are monitored throughout the process; perfusion or controlled feeding strategies are used to prevent inhibitory accumulation, especially in long-running differentiation processes for cultured red blood cells.
-
Closed, contamination-free environment
Cell therapy bioreactors must operate as fully closed, single-use systems with sterile connectors and inline sensors to comply with cGMP requirements.
Standard process workflow in cell therapy
Cell therapy manufacturing follows a multi-step, end-to-end workflow from starting material collection to the final formulated drug product. Each step requires its own equipment train and quality control measures. While the workflow below is illustrated for engineered immune cell therapies, the same logic applies to stem-cell-derived products such as cultured red blood cells, where activation/transduction is replaced by stage-wise differentiation from iPSCs or HSCs.
-
Cell collection (apheresis) or starting material sourcing
Peripheral blood mononuclear cells (PBMCs) are collected via leukapheresis from the patient (autologous) or from a healthy donor (allogeneic). For cultured red blood cell production, the starting material can also be an iPSC master cell bank or cord-blood-derived HSCs. Material is typically cryopreserved for shipping to the manufacturing site.
-
Cell isolation and enrichment
T cells, NK cells, CD34⁺ HSCs or other target populations are enriched from the apheresis product using counterflow centrifugal elutriation and antibody-based selection (e.g. CD3, CD4/CD8, CD62L, CD34).
-
Activation or lineage commitment
Isolated T cells are activated with anti-CD3/anti-CD28 magnetic beads. For erythroid programs, iPSCs or HSCs are committed to the hematopoietic and then erythroid lineage using defined cytokine cocktails (e.g. SCF, EPO, IL-3).
-
Genetic modification (transduction/transfection)
Cells are engineered using lentiviral or retroviral vectors, or via non-viral systems such as Sleeping Beauty, piggyBac or CRISPR delivered by electroporation or nanoparticles. For engineered red blood cells this step is used to introduce therapeutic payloads or correct genetic disorders.
-
Ex vivo expansion and differentiation
Engineered cells are cultivated in closed bioreactor systems with precise control of pH, DO, temperature and feeding. CAR-T expansion typically lasts 7–14 days; iPSC- or HSC-derived erythroid cultures run for 18–25 days through proliferation, maturation and enucleation phases — ideally in perfusion mode to reach the high cell densities required for transfusable units.
-
Harvest and formulation
Cells are washed, concentrated and formulated in cryopreservation or transfusion medium. Bead removal and final wash are performed in closed counterflow centrifugation systems.
-
Quality control and release testing
Identity, purity, potency, sterility, viability and transduction efficiency are tested. For cRBCs additional release tests include enucleation rate, hemoglobin content and oxygen-carrying capacity. Flow cytometry, qPCR and functional assays confirm product specifications.
-
Cryopreservation and infusion / transfusion
The cell therapy product is cryopreserved, shipped to the clinical site under controlled cold-chain conditions, thawed and infused or transfused into the patient.
Applikon bioreactor types for cell therapy
Applikon offers a complete portfolio of bioreactor formats that cover every stage of cell therapy manufacturing — from early process development and small-scale screening to cGMP-compliant clinical production of immune effector cells, stem-cell-derived products and bioreactor-grown red blood cells. All systems can be combined with Applikon bioprocess control platforms (my-Control, ez-Control, V-Control) for unified pH/DO/temperature cascades and feeding strategies across scales.
| Type | Scale | Key Use Cases | Cell-Therapy-Specific Features |
|---|---|---|---|
| Applikon MiniBio glass small-scale bioreactor | 250 mL – 1000 mL | Process development, media and cytokine screening, scale-down models for cell therapy and erythroid differentiation | True scale-down of larger bioreactors, low media cost, configurable head plate, gentle mixing for shear-sensitive cells, perfusion-ready |
| Applikon glass autoclavable bioreactors for cell therapy | 2–20 L | Process optimization, scale-up/scale-down models, R&D for autologous, allogeneic and cultured RBC processes | Multi-gas sparging options, multiple sensor ports, flexible configuration, BioSep cell retention compatible, perfusion-ready |
| AppliFlex ST single-use bioreactor (incl. GMP version) | 0.5–15 L (GMP: 0.5 / 3 L) | Clinical cell therapy manufacturing, autologous and allogeneic CGT applications, cGMP production of cultured red blood cells, seamless R&D-to-clinic transition | 3D-printed, fully customizable, fully closed system, cGMP-compliant materials and traceability, fast setup, reduced cross-contamination risk, perfusion-ready |
| Stainless steel bioreactors for allogeneic cell therapy and large-scale erythroid production | 15–5,000 L | Large-scale allogeneic cell therapy production, iPSC-derived cell expansion, industrial-scale cultured red blood cell manufacturing, repeated cGMP runs | 316L pharma-grade stainless steel (Ra < 0.4 µm), CIP/SIP, full automation, robust shear control, GMP documentation, perfusion-ready |
The Role of the AppliFlex ST GMP in Optimizing Cell Therapy Manufacturing
The AppliFlex ST GMP’s design is tailored to meet the challenges of both allogeneic and autologous cell therapies. Its single-use nature and fully closed system significantly reduce contamination risks, streamline the manufacturing process, and decrease downtime between production batches — enhancing safety and reducing overall production costs to make therapies more accessible.
Detailed Process Guide for Cell Therapy Manufacturing
From the distinction between autologous and allogeneic approaches through to the critical manufacturing steps, explore how the AppliFlex ST Single-Use supports each stage of cell therapy production.
Autologous cell therapy involves using a patient’s own cells, harvested from their body, processed, and then reintroduced. This method significantly reduces the risk of immune rejection since the cells are inherently recognized by the patient’s immune system. The Applikon AppliFlex ST GMP bioreactor plays a crucial role in autologous cell therapy manufacturing by offering precise environmental control for the expansion of these cells, ensuring they maintain their therapeutic properties and functionality.
Allogeneic cell therapy utilizes cells sourced from a donor rather than the patient. This approach allows for the mass production of cell therapy products, creating “off-the-shelf” solutions that can be used across multiple patients. Allogeneic cell therapy manufacturing in the AppliFlex ST GMP bioreactor ensures the growth of donor cells in a controlled, contamination-free environment — critical for the success of allogeneic therapy. The bioreactor’s precision in managing conditions like temperature, dissolved oxygen levels, and pH is essential for maintaining cell viability and performance.
Bioreactors are essential in the cell therapy manufacturing process, providing a controlled environment that mimics the body’s natural conditions to cultivate, expand, and manipulate cells. The Applikon AppliFlex ST GMP bioreactor, specifically designed for the needs of cell therapy solutions, offers unparalleled precision in controlling the culture environment, ensuring optimal cell growth and viability. Equipped with state-of-the-art software, this bioreactor optimizes process efficiency and enables simple and precise cell cultivation.
Cell therapy manufacturing begins with careful cell selection and collection. For autologous therapies, cells are sourced from the patient; for allogeneic therapies, donor cells require rigorous screening and compatibility testing. Collected cells then undergo processing and expansion under GMP standards — potentially including purification and genetic modifications to enhance therapeutic potential. Throughout the entire process, stringent quality control protocols ensure continuous monitoring and validation so that cells retain their desired characteristics and functionality for clinical application.
