CAR-T cell expansion platforms yield distinct T cell differentiation states

With investigators looking to expand engineered T cell therapies such as CAR-T to new tumor targets and patient populations, a variety of cell manufacturing platforms have been developed to scale manufacturing capacity using closed and/or automated systems. Such platforms are particularly useful for solid tumor targets, which typically require higher CAR-T cell doses. Although T cell phenotype and function are key attributes that often correlate with therapeutic efficacy, how manufacturing platforms influence the final CAR-T cell product is currently unknown. We compared 4 commonly used T cell manufacturing platforms (CliniMACS Prodigy, Xuri W25 rocking platform, G-Rex gas-permeable bioreactor, static bag culture) using identical media, stimulation, culture length, and donor starting material. Selected CD4+CD8+ cells were transduced with lentiviral vector incorporating a CAR targeting FGFR4, a promising target for pediatric sarcoma. We observed significant differences in overall expansion over the 14-day culture; bag cultures had the highest capacity for expansion while the Prodigy had the lowest (481-fold versus 84-fold, respectively). Strikingly, we also observed considerable differences in the phenotype of the final product, with the Prodigy significantly enriched for CCR7+CD45RA+ naïve/stem central memory (Tn/scm)-like cells at 46% compared to bag and G-Rex with 16% and 13%, respectively. Gene expression analysis also showed that Prodigy CAR-Ts are more naïve, less cytotoxic and less exhausted than bag, G-Rex, and Xuri CAR-Ts, and pointed to differences in cell metabolism that were confirmed via metabolic assays. We hypothesized that dissolved oxygen level, which decreased substantially during the final 3 days of the Prodigy culture, may contribute to the observed differences in T cell phenotype. By culturing bag and G-Rex cultures in 1% O2 from day 5 onward, we could generate >60% Tn/scm-like cells, with longer time in hypoxia correlating with a higher percentage of Tn/scm-like cells. Intriguingly, our results suggest that oxygenation is responsible, at least in part, for observed differences in T cell phenotype among bioreactors and suggest hypoxic culture as a potential strategy prevent T cell differentiation during expansion. Ultimately, our study demonstrates that selection of bioreactor system may have profound effects not only on the capacity for expansion, but also on the differentiation state of the resulting CAR-T cells.

Contract development and manufacturing organization selection: critical considerations that can make or break your cell and gene therapy development

BACKGROUND AIMS

With the increase in cell and gene therapy (CGT) clinical trials in recent years has come a subsequent increase in the number of contract development and manufacturing organizations (CDMOs). Successful transition from development and early-phase clinical trials to commercialization of a CGT product often depends on selecting the best-suited CDMO. However, many CGT companies are small biotech companies that lack expertise in the field or do not have experience selecting and transferring a process to a CDMO.

METHODS

Given the interest in this topic, a roundtable with CGT developers and CDMO members at the 2023 annual meeting of the International Society of Cell and Gene Therapy Paris discussed these critical aspects of product development, including technical expertise, risk sharing and timing of partnerships.

RESULTS AND CONCLUSIONS

Here, we'll analyze the considerations discussed by the panel and elaborate on other factors crucial for CGT development.

Engineering Improved CAR T Cell Products with A Multi-Cytokine Particle Platform for Hematologic and Solid Tumors

Despite the remarkable clinical efficacy of chimeric antigen receptor (CAR) T cells in hematological malignancies, only a subset of patients achieves a durable complete response (dCR). DCR has been correlated with CAR T cell products enriched with T cells memory phenotypes. Therefore, reagents that consistently promote memory phenotypes during the manufacturing of CAR T cells have the potential to significantly improve clinical outcomes. A novel modular multi-cytokine particle (MCP) platform is developed that combines the signals necessary for activation, costimulation, and cytokine support into a single "all-in-one" stimulation reagent for CAR T cell manufacturing. This platform allows for the assembly and screening of compositionally diverse MCP libraries to identify formulations tailored to promote specific phenotypes with a high degree of flexibility. The approach is leveraged to identify unique MCP formulations that manufacture CAR T cell products from diffuse large B cell patients   with increased proportions of memory-like phenotypes MCP-manufactured CAR T cells demonstrate superior anti-tumor efficacy in mouse models of lymphoma and ovarian cancer through enhanced persistence. These findings serve as a proof-of-principle of the powerful utility of the MCP platform to identify "all-in-one" stimulation reagents that can improve the effectiveness of cell therapy products through optimal manufacturing.

Primary T-cell-based delivery platform for in vivo synthesis of engineered proteins

Primary T cell has been transformed into a cell-based delivery platform that synthesizes complex biologics at the disease site with spatiotemporal resolution. This broadly applicable technology can circumvent toxicities due to systemic administration of biologics that necessitates the use of high doses and may diffuse to the healthy tissues. Its clinical translation, however, has been impeded by manufacturing bottlenecks. In this work, a range of process parameters were investigated for increasing the production yield of the primary T cells engineered for delivery function. Compared to the common spinoculation-based method, the transduction yield was enhanced ~2.5-fold by restricting the transduction reaction volume for maximizing the lentivector-to-T-cell contact. Cell density and cytokines used in the expansion process were adjusted to achieve >100-fold expansion of the T-cell-based delivery platform in 14 days, and the function of these cells was validated in vivo using intraperitoneally implanted tumor cells. The primary T-cell-based delivery platform has human applications because it can be scaled and administrated to express a broad range of therapeutic proteins (e.g., cytokines, interferons, enzymes, agonists, and antagonists) at the disease site, obviating the need for systemic delivery of large doses of these proteins.

Progress on Electro-Enhancement of Cell Manufacturing

With the long persistence of complex, chronic diseases in society, there is increasing motivation to develop cells as living medicine to treat diseases ranging from cancer to wounds. While cell therapies can significantly impact healthcare, the shortage of starter cells meant that considerable raw materials must be channeled solely for cell expansion, leading to expensive products with long manufacturing time which can prevent accessibility by patients who either cannot afford the treatment or have highly aggressive diseases and cannot wait that long. Over the last three decades, there has been increasing knowledge on the effects of electrical modulation on proliferation, but to the best of the knowledge, none of these studies went beyond how electro-control of cell proliferation may be extended to enhance industrial scale cell manufacturing. Here, this review is started by discussing the importance of maximizing cell yield during manufacturing before comparing strategies spanning biomolecular/chemical/physical to modulate cell proliferation. Next, the authors describe how factors governing invasive and non-invasive electrical stimulation (ES) including capacitive coupling electric field may be modified to boost cell manufacturing. This review concludes by describing what needs to be urgently performed to bridge the gap between academic investigation of ES to industrial applications.

A simulation-based comparison of centralized and point-of-care supply chain strategies for autologous cell therapy

BACKGROUND AIMS

The selection between centralized and point-of-care (POC) manufacturing supply-chain network design is a crucial consideration in the autologous cell therapy (AuCT) industry, as each approach offers its advantages and disadvantages.

METHODS

This study uses a simulation-based approach to compare and examine the two strategies using the supply chain for chimeric antigen receptor T-cell therapy manufacturing as an exemplar. When does it make sense to use one manufacturing strategy over another? Currently, major manufacturers in the AuCT industry use centralized supply-chain strategies predominantly in practice. The simulation results explain the reasons for this choice. To enhance the competitiveness of the POC strategy, two operation rules are proposed and tested with the simulation. The study uses key performance indicators such as cost, fulfillment time, service level, and resource utilization to provide generic guidelines based on the findings.

RESULTS

The results have revealed that (i) the centralized supply-chain strategy has a significant advantage at current demand levels of a few thousand products per year; (ii) "optimal capacity" exists for the POC strategy that minimizes the cost of goods and (iii) allowing part-time labor and order transshipment can significantly increase the competitiveness of the POC strategy.

CONCLUSIONS

This study may be useful in helping commercial manufacturers make informed decisions about their manufacturing approach to enhance their competitiveness in the market and to ensure a high level of patient benefit.

Cryopreservation of Human Bone Marrow Derived Mesenchymal Stem Cells at High Concentration Is Feasible

Introduction: For stem cell therapies to be adopted in mainstream health care, robust, reliable, and cost-effective storage and transport processes must be developed. Cryopreservation remains the best current platform for this purpose, and freezing cells at high concentration may have many benefits, including savings on cost and storage space, facilitating transport logistics, and reducing cryoprotectant volume. Cells, such as mesenchymal stem cells (MSCs), are typically frozen at 1 million cells per milliliter (mL), but the aim of this study is to examine the post-thaw attributes of human bone marrow derived MSCs (hBM-MSCs) frozen at 1, 5, and 10 million cells per mL. Methods: Thawed cells were assessed for their morphology, phenotypic marker expression, viability, apoptosis level, metabolic activity, proliferation, and osteogenic and adipogenic differentiation. Results: In this study, for the first time, it is shown that all assessed cells expressed the typical MSC markers (CD90, CD105, and CD73) and lacked the expression of CD14, CD20, CD34, CD45, and HLA-DR. In addition, all cells showed elongated fibroblastic morphology. Post-thaw viability was retained with no difference among the three concentrations. Moreover, no significant statistical difference was observed in the post-thaw apoptosis level, metabolic activity, proliferation, and osteogenic potential, indicating that these cells are amenable to cryopreservation at higher concentrations. Conclusion: The results of this study are of paramount importance to the development of manufacturing processes around a useful freezing concentration when cells are targeted to be stored for at least 6 months.

Bioprocessing Considerations towards the Manufacturing of Therapeutic Skeletal and Smooth Muscle Cells

Tissue engineering approaches within the muscle context represent a promising emerging field to address the current therapeutic challenges related with multiple pathological conditions affecting the muscle compartments, either skeletal muscle or smooth muscle, responsible for involuntary and voluntary contraction, respectively. In this review, several features and parameters involved in the bioprocessing of muscle cells are addressed. The cell isolation process is depicted, depending on the type of tissue (smooth or skeletal muscle), followed by the description of the challenges involving the use of adult donor tissue and the strategies to overcome the hurdles of reaching relevant cell numbers towards a clinical application. Specifically, the use of stem/progenitor cells is highlighted as a source for smooth and skeletal muscle cells towards the development of a cellular product able to maintain the target cell's identity and functionality. Moreover, taking into account the need for a robust and cost-effective bioprocess for cell manufacturing, the combination of muscle cells with biomaterials and the need for scale-up envisioning clinical applications are also approached.

Early dynamic changes in iPSC oxygen consumption rate predict future cardiomyocyte differentiation

Human induced pluripotent stem cells (iPSCs) hold great promise for reducing the mortality of cardiovascular disease by cellular replacement of infarcted cardiomyocytes (CMs). CM differentiation via iPSCs is a lengthy multiweek process and is highly subject to batch-to-batch variability, presenting challenges in current cell manufacturing contexts. Real-time, label-free control quality attributes (CQAs) are required to ensure efficient iPSC-derived CM manufacturing. In this work, we report that live oxygen consumption rate measurements are highly predictive CQAs of CM differentiation outcome as early as the first 72 h of the differentiation protocol with an accuracy of 93%. Oxygen probes are already incorporated in commercial bioreactors, thus methods presented in this work are easily translatable to the manufacturing setting. Detecting deviations in the CM differentiation trajectory early in the protocol will save time and money for both manufacturers and patients, bringing iPSC-derived CM one step closer to clinical use.

Large-Scale Production of Wholly Cellular Bioinks via the Optimization of Human Induced Pluripotent Stem Cell Aggregate Culture in Automated Bioreactors

Combining the sustainable culture of billions of human cells and the bioprinting of wholly cellular bioinks offers a pathway toward organ-scale tissue engineering. Traditional 2D culture methods are not inherently scalable due to cost, space, and handling constraints. Here, the suspension culture of human induced pluripotent stem cell-derived aggregates (hAs) is optimized using an automated 250 mL stirred tank bioreactor system. Cell yield, aggregate morphology, and pluripotency marker expression are maintained over three serial passages in two distinct cell lines. Furthermore, it is demonstrated that the same optimized parameters can be scaled to an automated 1 L stirred tank bioreactor system. This 4-day culture results in a 16.6- to 20.4-fold expansion of cells, generating approximately 4 billion cells per vessel, while maintaining >94% expression of pluripotency markers. The pluripotent aggregates can be subsequently differentiated into derivatives of the three germ layers, including cardiac aggregates, and vascular, cortical and intestinal organoids. Finally, the aggregates are compacted into a wholly cellular bioink for rheological characterization and 3D bioprinting. The printed hAs are subsequently differentiated into neuronal and vascular tissue. This work demonstrates an optimized suspension culture-to-3D bioprinting pipeline that enables a sustainable approach to billion cell-scale organ engineering.

Environmental oxygen affects ex vivo growth and proliferation of mesenchymal progenitors by modulating mitogen-activated protein kinase and mammalian target of rapamycin signaling

BACKGROUND AIMS

Stem and progenitor cells of hematopoietic and mesenchymal lineages reside in the bone marrow under low oxygen (O₂) saturation. O₂ levels used in ex vivo expansion of multipotent mesenchymal stromal cells (MSCs) affect proliferation, metabolism and differentiation.

METHODS

Using cell-based assays and transcriptome and proteome data, the authors compared MSC cultures simultaneously grown under a conventional 19.95% O₂ atmosphere or at 5% O₂.

RESULTS

In 5% O₂, MSCs showed better proliferation and higher self-renewal ability, most probably sustained by enhanced signaling activity of mitogen-activated protein kinase and mammalian target of rapamycin pathways. Non-oxidative glycolysis-based energy metabolism supported growth and proliferation in 5% O₂ cultures, whereas MSCs grown under 19.95% O₂ also utilized oxidative phosphorylation. Cytoprotection mechanisms used by cells under 5% O₂ differed from 19.95% O₂  suggesting differences in the triggers of cell stress between these two O₂  conditions.

CONCLUSIONS

Based on the potential benefits for the growth and metabolism of MSCs, the authors propose the use of 5% O₂ for MSC culture.

A chemically defined biomimetic surface for enhanced isolation efficiency of high-quality human mesenchymal stromal cells under xenogeneic/serum-free conditions

BACKGROUND AIMS

Mesenchymal stromal cells (MSCs) are one of the most frequently used cell types in regenerative medicine and cell therapy. Generating sufficient cell numbers for MSC-based therapies is constrained by (i) their low abundance in tissues of origin, which imposes the need for significant ex vivo cell expansion; (ii) donor-specific characteristics, including MSC frequency/quality, that decline with disease state and increasing age; and (iii) cellular senescence, which is promoted by extensive cell expansion and results in decreased therapeutic functionality. The final yield of a manufacturing process is therefore primarily determined by the applied isolation procedure and its efficiency in isolating therapeutically active cells from donor tissue. To date, MSCs are predominantly isolated using media supplemented with either serum or its derivatives, which poses safety and consistency issues.

METHODS

To overcome these limitations while enabling robust MSC production with constant high yield and quality, the authors developed a chemically defined biomimetic surface coating called isoMATRIX (denovoMATRIX GmbH, Dresden, Germany) and tested its performance during isolation of MSCs.

RESULTS

The isoMATRIX facilitates the isolation of significantly higher numbers of MSCs in xenogeneic (xeno)/serum-free and chemically defined conditions. The isolated cells display a smaller cell size and higher proliferation rate than those derived from a serum-containing isolation procedure and a strong immunomodulatory capacity. The high proliferation rates can be maintained up to 5 passages after isolation and cells even benefit from a switch towards a proliferation-specific MSC matrix (myMATRIX MSC) (denovoMATRIX GmbH, Dresden, Germany).

CONCLUSION

In sum, isoMATRIX promotes enhanced xeno/serum-free and chemically defined isolation of human MSCs and supports consistent and reliable cell performance for improved stem cell-based therapies.

Longitudinal two-dimensional gas chromatography mass spectrometry as a non-destructive at-line monitoring tool during cell manufacturing identifies volatile features correlative to cell product quality

BACKGROUND AIMS

Cell therapies have emerged as a potentially transformative therapeutic modality in many chronic and incurable diseases. However, inherent donor and patient variabilities, complex manufacturing processes, lack of well-defined critical quality attributes and unavailability of in-line or at-line process or product analytical technologies result in significant variance in cell product quality and clinical trial outcomes. New approaches for overcoming these challenges are needed to realize the potential of cell therapies.

METHODS

Here the authors developed an untargeted two-dimensional gas chromatography mass spectrometry (GC×GC-MS)-based method for non-destructive longitudinal at-line monitoring of cells during manufacturing to discover correlative volatile biomarkers of cell proliferation and end product potency.

RESULTS

Specifically, using mesenchymal stromal cell cultures as a model, the authors demonstrated that GC×GC-MS of the culture medium headspace can effectively discriminate between media types and tissue sources. Headspace GC×GC-MS identified specific volatile compounds that showed a strong correlation with cell expansion and product functionality quantified by indoleamine-2,3-dioxygenase and T-cell proliferation/suppression assays. Additionally, the authors discovered increases in specific volatile metabolites when cells were treated with inflammatory stimulation.

CONCLUSIONS

This work establishes GC×GC-MS as an at-line process analytical technology for cell manufacturing that could improve culture robustness and may be used to non-destructively monitor culture state and correlate with end product function.

Manufacturing Mesenchymal Stromal Cells for the Treatment of Osteoarthritis in Canine Patients: Challenges and Recommendations

The recent interest in advanced biologic therapies in veterinary medicine has opened up opportunities for new treatment modalities with considerable clinical potential. Studies with mesenchymal stromal cells (MSCs) from animal species have focused on in vitro characterization (mostly following protocols developed for human application), experimental testing in controlled studies and clinical use in veterinary patients. The ability of MSCs to interact with the inflammatory environment through immunomodulatory and paracrine mechanisms makes them a good candidate for treatment of inflammatory musculoskeletal conditions in canine species. Analysis of existing data shows promising results in the treatment of canine hip dysplasia, osteoarthritis and rupture of the cranial cruciate ligament in both sport and companion animals. Despite the absence of clear regulatory frameworks for veterinary advanced therapy medicinal products, there has been an increase in the number of commercial cell-based products that are available for clinical applications, and currently the commercial use of veterinary MSC products has outpaced basic research on characterization of the cell product. In the absence of quality standards for MSCs for use in canine patients, their safety, clinical efficacy and production standards are uncertain, leading to a risk of poor product consistency. To deliver high-quality MSC products for veterinary use in the future, there are critical issues that need to be addressed. By translating standards and strategies applied in human MSC manufacturing to products for veterinary use, in a collaborative effort between stem cell scientists and veterinary researchers and surgeons, we hope to facilitate the development of quality standards. We point out critical issues that need to be addressed, including a much higher level of attention to cell characterization, manufacturing standards and release criteria. We provide a set of recommendations that will contribute to the standardization of cell manufacturing methods and better quality assurance.

Characterizing human mesenchymal stromal cells' immune-modulatory potency using targeted lipidomic profiling of sphingolipids

Cell therapies are expected to increase over the next decade owing to increasing demand for clinical applications. Mesenchymal stromal cells (MSCs) have been explored to treat a number of diseases, with some successes in early clinical trials. Despite early successes, poor MSC characterization results in lessened therapeutic capacity once in vivo. Here, we characterized MSCs derived from bone marrow (BM), adipose tissue and umbilical cord tissue for sphingolipids (SLs), a class of bioactive lipids, using liquid chromatography/tandem mass spectrometry. We found that ceramide levels differed based on the donor's sex in BM-MSCs. We detected fatty acyl chain variants in MSCs from all three sources. Linear discriminant analysis revealed that MSCs separated based on tissue source. Principal component analysis showed that interferon-γ-primed and unstimulated MSCs separated according to their SL signature. Lastly, we detected higher ceramide levels in low indoleamine 2,3-dioxygenase MSCs, indicating that sphingomyelinase or ceramidase enzymatic activity may be involved in their immune potency.

Morphological landscapes from high content imaging reveal cytokine priming strategies that enhance mesenchymal stromal cell immunosuppression

Successful clinical translation of mesenchymal stromal cell (MSC) products has not been achieved in the United States and may be in large part due to MSC functional heterogeneity. Efforts have been made to identify "priming" conditions that produce MSCs with consistent immunomodulatory function; however, challenges remain with predicting and understanding how priming impacts MSC behavior. The purpose of this study was to develop a high throughput, image-based approach to assess MSC morphology in response to combinatorial priming treatments and establish morphological profiling as an effective approach to screen the effect of manufacturing changes (i.e., priming) on MSC immunomodulation. We characterized the morphological response of multiple MSC lines/passages to an array of Interferon-gamma (IFN-γ) and tumor necrosis factor-⍺ (TNF-⍺) priming conditions, as well as the effects of priming on MSC modulation of activated T cells and MSC secretome. Although considerable functional heterogeneity, in terms of T-cell suppression, was observed between different MSC lines and at different passages, this heterogeneity was significantly reduced with combined IFN-γ/TNF-⍺ priming. The magnitude of this change correlated strongly with multiple morphological features and was also reflected by MSC secretion of immunomodulatory factors, for example, PGE2, ICAM-1, and CXCL16. Overall, this study further demonstrates the ability of priming to enhance MSC function, as well as the ability of morphology to better understand MSC heterogeneity and predict changes in function due to manufacturing.

Metabolomics and cytokine profiling of mesenchymal stromal cells identify markers predictive of T-cell suppression

BACKGROUND AIMS

Mesenchymal stromal cells (MSCs) have shown great promise in the field of regenerative medicine, as many studies have shown that MSCs possess immunomodulatory function. Despite this promise, no MSC therapies have been licensed by the Food and Drug Administration. This lack of successful clinical translation is due in part to MSC heterogeneity and a lack of critical quality attributes. Although MSC indoleamine 2,3-dioxygnease (IDO) activity has been shown to correlate with MSC function, multiple predictive markers may be needed to better predict MSC function.

METHODS

Three MSC lines (two bone marrow-derived, one induced pluripotent stem cell-derived) were expanded to three passages. At the time of harvest for each passage, cell pellets were collected for nuclear magnetic resonance (NMR) and ultra-performance liquid chromatography mass spectrometry (MS), and media were collected for cytokine profiling. Harvested cells were also cryopreserved for assessing function using T-cell proliferation and IDO activity assays. Linear regression was performed on functional data against NMR, MS and cytokines to reduce the number of important features, and partial least squares regression (PLSR) was used to obtain predictive markers of T-cell suppression based on variable importance in projection scores.

RESULTS

Significant functional heterogeneity (in terms of T-cell suppression and IDO activity) was observed between the three MSC lines, as were donor-dependent differences based on passage. Omics characterization revealed distinct differences between cell lines using principal component analysis. Cell lines separated along principal component one based on tissue source (bone marrow-derived versus induced pluripotent stem cell-derived) for NMR, MS and cytokine profiles. PLSR modeling of important features predicted MSC functional capacity with NMR (R² = 0.86), MS (R² = 0.83), cytokines (R² = 0.70) and a combination of all features (R² = 0.88).

CONCLUSIONS

The work described here provides a platform for identifying markers for predicting MSC functional capacity using PLSR modeling that could be used as release criteria and guide future manufacturing strategies for MSCs and other cell therapies.

Scalable culture techniques to generate large numbers of purified human Schwann cells for clinical trials in human spinal cord and peripheral nerve injuries

OBJECTIVE

Schwann cells (SCs) have been shown to play an essential role in axon regeneration in both peripheral nerve injuries (PNIs) and spinal cord injuries (SCIs). The transplantation of SCs as an adjunctive therapy is currently under investigation in human clinical trials due to their regenerative capacity. Therefore, a reliable method for procuring large quantities of SCs from peripheral nerves is necessary. This paper presents a well-developed, validated, and optimized manufacturing protocol for clinical-grade SCs that are compliant with Current Good Manufacturing Practices (CGMPs).

METHODS

The authors evaluated the SC culture manufacturing data from 18 clinical trial participants who were recruited for autologous SC transplantation due to subacute SCI (n = 7), chronic SCI (n = 8), or PNIs (n = 3). To initiate autologous SC cultures, a mean nerve length of 11.8 ± 3.7 cm was harvested either from the sural nerve alone (n = 17) or with the sciatic nerve (n = 1). The nerves were digested with enzymes and SCs were isolated and further expanded in multiple passages to meet the dose requirements for transplantation.

RESULTS

An average yield of 87.2 ± 89.2 million cells at P2 and 150.9 ± 129.9 million cells at P3 with high viability and purity was produced. Cell counts and rates of expansion increased with each subsequent passage from P0 to P3, with the largest rate of expansion between P2 and P3. Larger harvest nerve lengths correlated significantly with greater yields at P0 and P1 (p < 0.05). In addition, a viability and purity above 90% was sustained throughout all passages in nearly all cell products.

CONCLUSIONS

This study presents reliable CGMP-compliant manufacturing methods for autologous SC products that are suitable for regenerative treatment of patients with SCI, PNI, or other conditions.

Interfacing Biomaterials with Synthetic T Cell Immunity

The clinical success of cancer immunotherapy is providing exciting opportunities for the development of new methods to detect and treat cancer more effectively. A new generation of biomaterials is being developed to interface with molecular and cellular features of immunity and ultimately shape or control anti-tumor responses. Recent advances that are supporting the advancement of engineered T cells are focused here. This class of cancer therapy has the potential to cure disease in subsets of patients, yet there remain challenges such as the need to improve response rates and safety while lowering costs to expand their use. To provide a focused overview, recent strategies in three areas of biomaterials research are highlighted: low-cost cell manufacturing to broaden patient access, noninvasive diagnostics for predictive monitoring of immune responses, and strategies for in vivo control that enhance anti-tumor immunity. These research efforts shed light on some of the challenges associated with T cell immunotherapy and how engineered biomaterials that interface with synthetic immunity are gaining traction to solve these challenges.

Engineering microenvironments for manufacturing therapeutic cells

There are a growing number of globally approved products and clinical trials utilizing autologous and allogeneic therapeutic cells for applications in regenerative medicine and immunotherapies. However, there is a need to develop rapid and cost-effective methods for manufacturing therapeutically effective cells. Furthermore, the resulting manufactured cells may exhibit heterogeneities that result in mixed therapeutic outcomes. Engineering approaches that can provide distinct microenvironmental cues to these cells may be able to enhance the growth and characterization of these cell products. This mini-review describes strategies to potentially enhance the expansion of therapeutic cells with biomaterials and bioreactors, as well as to characterize the cell products with microphysiological systems. These systems can provide distinct cues to maintain the quality attributes of the cells and evaluate their function in physiologically relevant conditions.

Advances in automated cell washing and concentration

The successful commercialization of cell therapies requires thorough planning and consideration of product quality, cost and scale of the manufacturing process. The implementation of automation can be central to a robust and reproducible manufacturing process at industrialized scales. There have been a number of wash-and-concentrate devices developed for cell manufacturing. These technologies have arisen from transfusion medicine, hematopoietic stem cell and biologics manufacturing where operating mechanisms are distinct from manual centrifugation. This review describes the historical origin and fundamental technologies underlying each currently available wash-and-concentrate device as well as their relative advantages and disadvantages in cell therapy applications. Understanding the specific attributes and limitations of these technologies is essential to optimizing cell therapy manufacturing.

Localized Sampling Enables Monitoring of Cell State via Inline Electrospray Ionization Mass Spectrometry

Nascent advanced therapies, including regenerative medicine and cell and gene therapies, rely on the production of cells in bioreactors that are highly heterogeneous in both space and time. Unfortunately, advanced therapies have failed to reach a wide patient population due to unreliable manufacturing processes that result in batch variability and cost prohibitive production. This can be attributed largely to a void in existing process analytical technologies (PATs) capable of characterizing the secreted critical quality attribute (CQA) biomolecules that correlate with the final product quality. The Dynamic Sampling Platform (DSP) is a PAT for cell bioreactor monitoring that can be coupled to a suite of sensor techniques to provide real-time feedback on spatial and temporal CQA content in situ. In this study, DSP is coupled with electrospray ionization mass spectrometry and direct-from-culture sampling to obtain measures of CQA content in bulk media and the cell microenvironment throughout the entire cell culture process (≈3 weeks). Post hoc analysis of this real-time data reveals that sampling from the microenvironment enables cell state monitoring (e.g., confluence, differentiation). These results demonstrate that an effective PAT should incorporate both spatial and temporal resolution to serve as an effective input for feedback control in biomanufacturing.

Spatiotemporal readiness is key to preparing regenerative medicine for the clinic

Tweetable abstract Successful translation of regenerative medicine projects to the clinic requires attention to the complex interaction of spatial and timing issues from manufacturing to clinical use.

Dissolvable Gelatin-Based Microcarriers Generated through Droplet Microfluidics for Expansion and Culture of Mesenchymal Stromal Cells

Microcarriers are synthetic particles used in bioreactor-based cell manufacturing of anchorage-dependent cells to promote proliferation at efficient physical volumes, mainly by increasing the surface area-to-volume ratio. Mesenchymal stromal cells (MSCs) are adherent cells that are used for numerous clinical trials of autologous and allogeneic cell therapy, thus requiring avenues for large-scale cell production at efficiently low volumes and cost. Here, a dissolvable gelatin-based microcarrier is developed for MSC expansion. This novel microcarrier shows comparable cell attachment efficiency and proliferation rate when compared to several commercial microcarriers, but with higher harvesting yield due to the direct dissolution of microcarrier particles and thus reduced cell loss at the cell harvesting step. Furthermore, gene expression and in vitro differentiation suggest that MSCs cultured on gelatin microcarriers maintain trilineage differentiation with similar adipogenic differentiation efficiency and higher chondrogenic and osteogenic differentiation efficiency when compared to MSCs cultured on 2D planar polystyrene tissue culture flask; on the contrary, MSCs cultured on conventional microcarriers appear to be bipotent along osteochondral lineages whereby adipogenic differentiation potential is impeded. These results suggest that these gelatin microcarriers are suitable for MSC culture and expansion, and can also potentially be extended for other types of anchorage-dependent cells.

Lentivirus Manufacturing Process for Primary T-Cell Biofactory Production

A process for maximizing the titer of lentivirus particles, deemed to be a necessity for transducing primary cells, is developed. Lentivirus particles, with a set of transgenes encoding an artificial cell-signaling pathway, are used to transform primary T cells as vectors for calibrated synthesis of desired proteins in situ, that is, T-cell biofactory cells. The process is also used to generate primary T cells expressing antigen-specific chimeric antigen receptors, that is, CAR T cells. The two differently engineered primary T cells are expanded and validated for their respective functions, that is, calibrated synthesis of desired proteins upon engaging the target cells, which is specific for the T-cell biofactory cells, and cytolysis of the target cells common to both types of cells. The process is compliant with current Good Manufacturing Practices and can be used to support the scale-up for clinical translation.

Chemistry, manufacturing and controls for gene modified hematopoietic stem cells

Gene modification of hematopoietic stem cells is increasingly becoming popular as a therapeutic approach, given the recent approvals and the number of new applications for clinical trials targeting monogenetic and immunodeficiency disorders. Technological advances in stem cell selection, culture, transduction and gene editing now allow for efficient ex vivo genetic manipulation of stem cells. Gene-addition techniques using viral vectors (mainly retrovirus- and lentivirus-based) and gene editing using various targeted nuclease platforms (e.g., Zinc finger, TALEN and Crispr/Cas9) are being applied to the treatment of multiple genetic and immunodeficiency disorders. Herein, the current state of the art in manufacturing and critical assays that are required for ex vivo manipulation of stem cells are addressed. Important quality control and safety assays that need to be planned early in the process development phase of these products for regulatory approval are also highlighted.

Dynamic mass spectrometry probe for electrospray ionization mass spectrometry monitoring of bioreactors for therapeutic cell manufacturing

Large-scale manufacturing of therapeutic cells requires bioreactor technologies with online feedback control enabled by monitoring of secreted biomolecular critical quality attributes (CQAs). Electrospray ionization mass spectrometry (ESI-MS) is a highly sensitive label-free method to detect and identify biomolecules, but requires extensive sample preparation before analysis, making online application of ESI-MS challenging. We present a microfabricated, monolithically integrated device capable of continuous sample collection, treatment, and direct infusion for ESI-MS detection of biomolecules in high-salt solutions. The dynamic mass spectrometry probe (DMSP) uses a microfluidic mass exchanger to rapidly condition samples for online MS analysis by removing interfering salts, while concurrently introducing MS signal enhancers to the sample for sensitive biomolecular detection. Exploiting this active conditioning capability increases MS signal intensity and signal-to-noise ratio. As a result, sensitivity for low-concentration biomolecules is significantly improved, and multiple proteins can be detected from chemically complex samples. Thus, the DMSP has significant potential to serve as an enabling portion of a novel analytical tool for discovery and monitoring of CQAs relevant to therapeutic cell manufacturing.

Rescuing mesenchymal stem cell regenerative properties on hydrogel substrates post serial expansion

The use of human mesenchymal stem/stromal cells (hMSCs) in most clinical trials requires millions of cells/kg, necessitating ex vivo expansion typically on stiff substrates (tissue culture polystyrene [TCPS]), which induces osteogenesis and replicative senescence. Here, we quantified how serial expansion on TCPS influences proliferation, expression of hMSC-specific surface markers, mechanosensing, and secretome. Results show decreased proliferation and surface marker expression after five passages (P5) and decreased mechanosensing ability and cytokine production at later passages (P11-P12). Next, we investigated the capacity of poly(ethylene glycol) hydrogel matrices (E ~ 1 kPa) to rescue hMSC regenerative properties. Hydrogels reversed the reduction in cell surface marker expression observed at P5 on TCPS and increased secretion of cytokines for P11 hMSCs. Collectively, these results show that TCPS expansion significantly changes functional properties of hMSCs. However, some changes can be rescued by using hydrogels, suggesting that tailoring material properties could improve in vitro expansion methods.

Peak MSC-Are We There Yet?

Human mesenchymal stem cells (hMSCs) are a critical raw material for many regenerative medicine products, including cell-based therapies, engineered tissues, or combination products, and are on the brink of radically changing how the world of medicine operates. Their unique characteristics, potential to treat many indications, and established safety profile in more than 800 clinical trials have contributed to their current consumption and will only fuel future demand. Given the large target patient populations with typical dose sizes of 10's to 100's of millions of cells per patient, and engineered tissues being constructed with 100's of millions to billions of cells, an unprecedented demand has been created for hMSCs. The fulfillment of this demand faces an uphill challenge in the limited availability of large quantities of pharmaceutical grade hMSCs for the industry—fueling the need for parallel rapid advancements in the biomanufacturing of this living critical raw material. Simply put, hMSCs are no different than technologies like transistors, as they are a highly technical and modular product that requires stringent control over manufacturing that can allow for high quality and consistent performance. As hMSC manufacturing processes are optimized, it predicts a future time of abundance for hMSCs, where scientists and researchers around the world will have access to a consistent and readily available supply of high quality, standardized, and economical pharmaceutical grade product to buy off the shelf for their applications and drive product development—this is “Peak MSC.”

The re-emergence of sodium ion batteries: testing, processing, and manufacturability

With the re-emergence of sodium ion batteries (NIBs), we discuss the reasons for the recent interests in this technology and discuss the synergies between lithium ion battery (LIB) and NIB technologies and the potential for NIB as a "drop-in" technology for LIB manufacturing. The electrochemical testing of sodium materials in sodium metal anode arrangements is reviewed. The performance, stability, and polarization of the sodium in these test cells lead to alternative testing in three-electrode and alternative anode cell configurations. NIB manufacturability is also discussed, together with the impact that the material stability has upon the electrodes and coating. Finally, full-cell NIB technologies are reviewed, and literature proof-of-concept cells give an idea of some of the key differences in the testing protocols of these batteries. For more commercially relevant formats, safety, passive voltage control through cell balancing and cell formation aspects are discussed.

Engineering Scalable Manufacturing of High-Quality Stem Cell-Derived Cardiomyocytes for Cardiac Tissue Repair

Recent advances in the differentiation and production of human pluripotent stem cell (hPSC)-derived cardiomyocytes (CMs) have stimulated development of strategies to use these cells in human cardiac regenerative therapies. A prerequisite for clinical trials and translational implementation of hPSC-derived CMs is the ability to manufacture safe and potent cells on the scale needed to replace cells lost during heart disease. Current differentiation protocols generate fetal-like CMs that exhibit proarrhythmogenic potential. Sufficient maturation of these hPSC-derived CMs has yet to be achieved to allow these cells to be used as a regenerative medicine therapy. Insights into the native cardiac environment during heart development may enable engineering of strategies that guide hPSC-derived CMs to mature. Specifically, considerations must be made in regard to developing methods to incorporate the native intercellular interactions and biomechanical cues into hPSC-derived CM production that are conducive to scale-up.

Inducible indoleamine 2,3-dioxygenase 1 and programmed death ligand 1 expression as the potency marker for mesenchymal stromal cells

AIM

Establishment of a potency assay in the manufacturing of clinical-grade mesenchymal stromal cells (MSCs) has been a challenge due to issues of relevance to function, timeline and variability of responder cells. In this study, we attempted to develop a potency assay for MSCs.

METHODS

Clinical-grade bone marrow-derived MSCs were manufactured. The phenotype and immunosuppressive functions of the MSCs were evaluated based on the International Society for Cellular Therapy guidelines. Resting MSCs licensed by interferon (IFN)-γ exposure overnight were evaluated for changes in immune suppression and immune-relevant proteins. The relationship of immune-relevant protein expression with immunosuppression of MSCs was analyzed.

RESULTS

MSC supressed third-party T-lymphocyte proliferation with high inter-donor and inter-test variability. The suppression of T-lymphocyte proliferation by IFN-γ-licensed MSCs correlated with that by resting MSCs. Many cellular proteins were up-regulated after IFN-γ exposure, including indoleamine 2,3-dioxygenase 1 (IDO-1), programmed death ligand 1 (PD-L1), vascular cell adhesion molecule 1 (VCAM-1), intercellular adhesion molecule 1 (ICAM-1) and bone marrow stromal antigen 2 (BST-2). The expression levels of IDO-1 and PD-L1 on licensed MSCs, not VCAM-1, ICAM-1 or BST-2 on licensed MSCs, correlated with MSC suppression of third-party T-cell proliferation.

CONCLUSION

A flow cytometry-based assay of MSCs post-IFN-γ exposure measuring expression of intracellular protein IDO-1 and cell surface protein PD-L1 captures two mechanisms of suppression and offers the potential of a relevant, rapid assay for MSC-mediated immune suppression that would fit with the manufacturing process.

Off the shelf cellular therapeutics: Factors to consider during cryopreservation and storage of human cells for clinical use

The field of cellular therapeutics has immense potential, affording an exciting array of applications in unmet medical needs. One of several key issues is an emphasis on getting these therapies from bench to bedside without compromising safety and efficacy. The successful commercialization of cellular therapeutics will require many to extend the shelf-life of these therapies beyond shipping "fresh" at ambient or chilled temperatures for "just in time" infusion. Cryopreservation is an attractive option and offers potential advantages, such as storing and retaining patient samples in case of a relapse, banking large quantities of allogeneic cells for broader distribution and use and retaining testing samples for leukocyte antigen typing and matching. However, cryopreservation is only useful if cells can be reanimated to physiological life with negligible loss of viability and functionality. Also critical is the logistics of storing, processing and transporting cells in clinically appropriate packaging systems and storage devices consistent with quality and regulatory standards. Rationalized approaches to develop commercial-scale cell therapies require an efficient cryopreservation system that provides the ability to inventory standardized products with maximized shelf life for later on-demand distribution and use, as well as a method that is scientifically sound and optimized for the cell of interest. The objective of this review is to bridge this gap between the basic science of cryobiology and its application in this context by identifying several key aspects of cryopreservation science in a format that may be easily integrated into mainstream cell therapy manufacture.

Microfluidic Transduction Harnesses Mass Transport Principles to Enhance Gene Transfer Efficiency

Ex vivo gene therapy using lentiviral vectors (LVs) is a proven approach to treat and potentially cure many hematologic disorders and malignancies but remains stymied by cumbersome, cost-prohibitive, and scale-limited production processes that cannot meet the demands of current clinical protocols for widespread clinical utilization. However, limitations in LV manufacture coupled with inefficient transduction protocols requiring significant excess amounts of vector currently limit widespread implementation. Herein, we describe a microfluidic, mass transport-based approach that overcomes the diffusion limitations of current transduction platforms to enhance LV gene transfer kinetics and efficiency. This novel ex vivo LV transduction platform is flexible in design, easy to use, scalable, and compatible with standard cell transduction reagents and LV preparations. Using hematopoietic cell lines, primary human T cells, primary hematopoietic stem and progenitor cells (HSPCs) of both murine (Sca-1⁺) and human (CD34⁺) origin, microfluidic transduction using clinically processed LVs occurs up to 5-fold faster and requires as little as one-twentieth of LV. As an in vivo validation of the microfluidic-based transduction technology, HSPC gene therapy was performed in hemophilia A mice using limiting amounts of LV. Compared to the standard static well-based transduction protocols, only animals transplanted with microfluidic-transduced cells displayed clotting levels restored to normal.

Manufacture and preparation of human placenta-derived mesenchymal stromal cells for local tissue delivery

BACKGROUND

In this study we describe the development of a Current Good Manufacturing Practice (CGMP)-compliant process to isolate, expand and bank placenta-derived mesenchymal stromal cells (PMSCs) for use as stem cell therapy. We characterize the viability, proliferation and neuroprotective secretory profile of PMSCs seeded on clinical-grade porcine small intestine submucosa extracellular matrix (SIS-ECM; Cook Biotech).

METHODS

PMSCs were isolated from early gestation placenta chorionic villus tissue via explant culture. Cells were expanded, banked and screened. Purity and expression of markers of pluripotency were determined using flow cytometry. Optimal loading density and viability of PMSCs on SIS-ECM were determined using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) cell proliferation and fluorescent live/dead assays, respectively. Growth factors secretion was analyzed using enzyme-linked immunosorbent assays (ELISA).

RESULTS

PMSCs were rapidly expanded and banked. Viable Master and Working Cell Banks were stable with minimal decrease in viability at 6 months. All PMSCs were sterile, free from Mycoplasma species, karyotypically normal and had low endotoxin levels. PMSCs were homogeneous by immunophenotyping and expressed little to no pluripotency markers. Optimal loading density on SIS-ECM was 3-5 × 10⁵ cells/cm², and seeded cells were >95% viable. Neurotrophic factor secretion was detectable from PMSCs seeded on plastic and SIS-ECM with variability between donor lots.

DISCUSSION

PMSCs from early gestation placental tissues can be rapidly expanded and banked in stable, viable cell banks that are free from contaminating agents, genetically normal and pure. PMSC delivery can be accomplished by using SIS-ECM, which maintains cell viability and protein secretion. Future work in vivo is necessary to optimize cell seeding and transplantation to maximize therapeutic capabilities.

A novel filtration system for point of care washing of cellular therapy products

The cell therapy industry would greatly benefit from a simple point of care solution to remove dimethylsulphoxide (DMSO) from small-volume thawed cell suspensions before injection. A novel dead-end filtration device has been designed and validated, which takes advantage of the higher density of thawed cell suspensions to remove the DMSO and protein impurities from the cell suspension without fouling the filter membrane. The filter was designed to avoid fluid circuits and minimize the surface area that is contacted by the cell suspension, thus reducing cell losses by design. The filtration process was established through optimization of the fluid flow configuration, backflush cycles and filter geometry. Overall, this novel filtration device allows for a 1 ml of thawed cryopreserved cell suspensions, containing 10⁷ cells of a fetal lung fibroblast cell line (MRC-5), to be washed in less than 30 min. More than 95% of the DMSO and up to 94% of the albumin-fluorescein-isothiocyanate content can be removed while the viable cell recovery is higher than 80%. It is also demonstrated that this system can be used for bone marrow-derived human mesenchymal stem cells with more than 73% cell recovery and 85% DMSO reduction. This is the first time that a dead end (normal) filtration process has been used to successfully wash high-density human cell suspensions. In practice, this novel solid-liquid separation technology fills the need for small-volume washing in closed processing systems for cellular therapies. Copyright © 2016 John Wiley & Sons, Ltd.