The translation of cell-based therapies: clinical landscape and manufacturing challenges

Cell therapy-processing economics: small-scale microfactories as a stepping stone toward large-scale macrofactories

AIM

Manufacturing methods for cell-based therapies differ markedly from those established for noncellular pharmaceuticals and biologics. Attempts to 'shoehorn' these into existing frameworks have yielded poor outcomes. Some excellent clinical results have been realized, yet emergence of a 'blockbuster' cell-based therapy has so far proved elusive.

MATERIALS & METHODS

The pressure to provide these innovative therapies, even at a smaller scale, remains. In this process, economics research paper, we utilize cell expansion research data combined with operational cost modeling in a case study to demonstrate the alternative ways in which a novel mesenchymal stem cell-based therapy could be provided at small scale.

RESULTS & CONCLUSIONS

This research outlines the feasibility of cell microfactories but highlighted that there is a strong pressure to automate processes and split the quality control cost-burden over larger production batches. The study explores one potential paradigm of cell-based therapy provisioning as a potential exemplar on which to base manufacturing strategy.

Enhancing cell and gene therapy manufacture through the application of advanced fluorescent optical sensors (Review)

Cell and gene therapies (CGTs) are examples of future therapeutics that can be used to cure or alleviate the symptoms of disease, by repairing damaged tissue or reprogramming defective genetic information. However, despite the recent advancements in clinical trial outcomes, the path to wide-scale adoption of CGTs remains challenging, such that the emergence of a "blockbuster" therapy has so far proved elusive. Manufacturing solutions for these therapies require the application of scalable and replicable cell manufacturing techniques, which differ markedly from the existing pharmaceutical incumbent. Attempts to adopt this pharmaceutical model for CGT manufacture have largely proved unsuccessful. The most significant challenges facing CGT manufacturing are process analytical testing and quality control. These procedures would greatly benefit from improved sensory technologies that allow direct measurement of critical quality attributes, such as pH, oxygen, lactate and glucose. In turn, this would make manufacturing more robust, replicable and standardized. In this review, the present-day state and prospects of CGT manufacturing are discussed. In particular, the authors highlight the role of fluorescent optical sensors, focusing on their strengths and weaknesses, for CGT manufacture. The review concludes by discussing how the integration of CGT manufacture and fluorescent optical sensors could augment future bioprocessing approaches.

Long-term drug modification to the surface of mesenchymal stem cells by the avidin-biotin complex method

Mesenchymal stem cells (MSCs) have various functions, making a significant contribution to tissue repair. On the other hand, the viability and function of MSCs are not lasting after an in vivo transplant, and the therapeutic effects of MSCs are limited. Although various chemical modification methods have been applied to MSCs to improve their viability and function, most of conventional drug modification methods are short-term and unstable and cause cytotoxicity. In this study, we developed a method for long-term drug modification to C3H10T1/2 cells, murine mesenchymal stem cells, without any damage, using the avidin-biotin complex method (ABC method). The modification of NanoLuc luciferase (Nluc), a reporter protein, to C3H10T1/2 cells by the ABC method lasted for at least 14 days in vitro without major effects on the cellular characteristics (cell viability, cell proliferation, migration ability, and differentiation ability). Moreover, in vivo, the surface Nluc modification to C3H10T1/2 cells by the ABC method lasted for at least 7 days. Therefore, these results indicate that the ABC method may be useful for long-term surface modification of drugs and for effective MSC-based therapy.

High-throughput assessment of mechanical properties of stem cell derived red blood cells, toward cellular downstream processing

Stem cell products, including manufactured red blood cells, require efficient sorting and purification methods to remove components potentially harmful for clinical application. However, standard approaches for cellular downstream processing rely on the use of specific and expensive labels (e.g. FACS or MACS). Techniques relying on inherent mechanical and physical properties of cells offer high-throughput scalable alternatives but knowledge of the mechanical phenotype is required. Here, we characterized for the first time deformability and size changes in CD34+ cells, and expelled nuclei, during their differentiation process into red blood cells at days 11, 14, 18 and 21, using Real-Time Deformability Cytometry (RT-DC) and Atomic Force Microscopy (AFM). We found significant differences (p < 0.0001; standardised mixed model) between the deformability of nucleated and enucleated cells, while they remain within the same size range. Expelled nuclei are smaller thus could be removed by size-based separation. An average Young's elastic modulus was measured for nucleated cells, enucleated cells and nuclei (day 14) of 1.04 ± 0.47 kPa, 0.53 ± 0.12 kPa and 7.06 ± 4.07 kPa respectively. Our identification and quantification of significant differences (p < 0.0001; ANOVA) in CD34+ cells mechanical properties throughout the differentiation process could enable development of new routes for purification of manufactured red blood cells.

Building with intent: technologies and principles for engineering mammalian cell-based therapies to sense and respond

The engineering of cells as programmable devices has enabled therapeutic strategies that could not otherwise be achieved. Such strategies include recapitulating and enhancing native cellular functions and composing novel functions. These novel functions may be composed using both natural and engineered biological components, with the latter exemplified by the development of synthetic receptor and signal transduction systems. Recent advances in implementing these approaches include the treatment of cancer, where the most clinical progress has been made to date, and the treatment of diabetes. Principles for engineering cell-based therapies that are safe and effective are increasingly needed and beginning to emerge, and will be essential in the development of this new class of therapeutics.

Toward Exosome-Based Therapeutics: Isolation, Heterogeneity, and Fit-for-Purpose Potency

Exosomes are defined as submicron (30-150 nm), lipid bilayer-enclosed extracellular vesicles (EVs), specifically generated by the late endosomal compartment through fusion of multivesicular bodies with the plasma membrane. Produced by almost all cells, exosomes were originally considered to represent just a mechanism for jettisoning unwanted cellular moieties. Although this may be a major function in most cells, evolution has recruited the endosomal membrane-sorting pathway to duties beyond mere garbage disposal, one of the most notable examples being its cooption by retroviruses for the generation of Trojan virions. It is, therefore, tempting to speculate that certain cell types have evolved an exosome subclass active in intracellular communication. We term this EV subclass "signalosomes" and define them as exosomes that are produced by the "signaling" cells upon specific physiological or environmental cues and harbor cargo capable of modulating the programming of recipient cells. Our recent studies have established that signalosomes released by mesenchymal stem/stromal cells (MSCs) represent the main vector of MSC immunomodulation and therapeutic action in animal models of lung disease. The efficacy of MSC-exosome treatments in a number of preclinical models of cardiovascular and pulmonary disease supports the promise of application of exosome-based therapeutics across a wide range of pathologies within the near future. However, the full realization of exosome therapeutic potential has been hampered by the absence of standardization in EV isolation, and procedures for purification of signalosomes from the main exosome population. This is mainly due to immature methodologies for exosome isolation and characterization and our incomplete understanding of the specific characteristics and molecular composition of signalosomes. In addition, difficulties in defining metrics for potency of exosome preparations and the challenges of industrial scale-up and good manufacturing practice compliance have complicated smooth and timely transition to clinical development. In this manuscript, we focus on cell culture conditions, exosome harvesting, dosage, and exosome potency, providing some empirical guidance and perspectives on the challenges in bringing exosome-based therapies to clinic.

Annexin-enriched osteoblast-derived vesicles act as an extracellular site of mineral nucleation within developing stem cell cultures

The application of extracellular vesicles (EVs) as natural delivery vehicles capable of enhancing tissue regeneration could represent an exciting new phase in medicine. We sought to define the capacity of EVs derived from mineralising osteoblasts (MO-EVs) to induce mineralisation in mesenchymal stem cell (MSC) cultures and delineate the underlying biochemical mechanisms involved. Strikingly, we show that the addition of MO-EVs to MSC cultures significantly (P < 0.05) enhanced the expression of alkaline phosphatase, as well as the rate and volume of mineralisation beyond the current gold-standard, BMP-2. Intriguingly, these effects were only observed in the presence of an exogenous phosphate source. EVs derived from non-mineralising osteoblasts (NMO-EVs) were not found to enhance mineralisation beyond the control. Comparative label-free LC-MS/MS profiling of EVs indicated that enhanced mineralisation could be attributed to the delivery of bridging collagens, primarily associated with osteoblast communication, and other non-collagenous proteins to the developing extracellular matrix. In particular, EV-associated annexin calcium channelling proteins, which form a nucleational core with the phospholipid-rich membrane and support the formation of a pre-apatitic mineral phase, which was identified using infrared spectroscopy. These findings support the role of EVs as early sites of mineral nucleation and demonstrate their value for promoting hard tissue regeneration.

Allogeneic cell therapy manufacturing: process development technologies and facility design options

Currently, promising outcomes from clinical trials of allogeneic cells, especially allogeneic mesenchymal stromal cells, fibroblasts, keratinocytes, and human cardiac stem cells, have encouraged research institutions, small and medium enterprises (SMEs), and big pharmaceutical companies to invest and focus on developing allogeneic cell therapy products. Commercial and large-scale production of allogeneic cell therapy products requires unique capabilities to develop technologies that generate safe and effective allogeneic cells/cell lines and their fully characterized master/working banks. In addition, it is necessary to design robust upstream and downstream manufacturing processes, and establish integrated, well-designed manufacturing facilities to produce high quality affordable products in accordance with current GMP regulations for the production of cell therapy products. Areas covered: The authors highlight: the recent advances in the development of allogeneic products, the available options to develop robust manufacturing processes, and facility design considerations. Expert opinion: Currently, there are multiple challenges in development of allogeneic cell therapy products. Indeed, the field is still in its infancy; with technologies and regulations still under development, as is our understanding of the mechanisms of action in the body and their interaction with the host immune system. Their characterization and testing is also an emerging and very complex area.

Challenges of running a GMP facility for regenerative medicine in a public hospital

Advanced therapy medicinal products represent a new generation of medicinal products for regenerative medicine. Since the implementation of the EU regulation for this innovative class of drugs, the academic and hospital institutions have played a central role in their development and manufacture. For these institutions that are not familiar with the industrial context, being in compliance with the pharmaceutical standards is extremely challenging. This report describes how we dealt with some specific issues during our hospital-based GMP experience. Furthermore, we identify as a future perspective the consistent stimulating contribution that a public entity can ensure for advanced therapy medicinal product development and licensing.

Stem Cell Research and Clinical Translation: A Roadmap about Good Clinical Practice and Patient Care

The latest research achievements in the field of stem cells led in 2016 to the publication of "Guidelines for Stem Cell Research and Clinical Translation" by the International Society for Stem Cell Research (ISSCR). Updating the topics covered in previous publications, the new recommendations offer interesting ethical and scientific insights. Under the common principles of research integrity, protection of patient's welfare, respect for the research subjects, transparency and social justice, the centrality of good clinical practice, and informed consent in research and translational medicine is supported. The guidelines implement the abovementioned publications, requiring rigor in all areas of research, promoting the validity of the scientific activity results and emphasizing the need for an accurate and efficient public communication. This paper aims to analyze the aforementioned guidelines in order to provide a valid interpretive tool for experts. In particular, a research activity focused on the bioethical, scientific, and social implications of the new recommendations is carried out in order to provide food for thought. Finally, as an emerging issue of potential impact of current guidelines, an overview on implications of compensation for egg donation is offered.

Addressing Pressing Needs in the Development of Advanced Therapies

The commercial development of advanced therapy medicinal products (ATMPs) represents great opportunity for therapeutic innovation but is beset by many challenges for its developers. Although the ATMP field continues to progress at a rapid pace, evidenced by the increasing number of clinical trials conducted over the past few years, several factors continue to complicate the introduction of ATMPs as a curative treatment for multiple disease types, by blocking their translational pathway from research to the patient. While several recent publications (Trounson and McDonald, 2015; Abou-El-Enein et al., 2016a,b) as well as an Innovative Medicines Initiative consultation (IMI, 2016) this year have highlighted the major gaps in ATMP development, with manufacturing, regulatory, and reimbursement issues at the forefront, there remains to be formulated a coherent strategy to address these by bringing the relevant stakeholders to a single forum, whose task it would be to design and execute a delta plan to alleviate the most pressing bottlenecks. This article focuses on two of the most urgent areas in need of attention in ATMP development, namely manufacturing and reimbursement, and promotes the concept of innovation-dedicated research infrastructures to support a multi-sector approach for ensuring the successful development, entry, and ensuing survival of ATMPs in the healthcare market.

Cell-Surface Expression Levels Are Important for Fine-Tuning the Performance of Receptor Tyrosine Kinase-Based Signalobodies

As receptor tyrosine kinases (RTKs) play important roles in cell-fate control of various cell types, engineered RTKs that could respond to inexpensive ligands might drastically reduce the cost of producing desired cells for various applications in regenerative medicine. We developed several engineered RTKs named "signalobodies" in which the ligand-recognition domain of RTKs is replaced by single-chain Fv for enabling recognition of a specific antigen. However, the remaining concern was the dysregulation of antigen-dependent on/off signaling of the signalobodies. This study aims at fine-tuning the performance of the signalobodies based on three RTKs (fibroblast growth factor receptor 1, insulin receptor, and c-fms). To this end, the cell-surface expression levels of the RTK-based signalobodies were altered by locating their genes either upstream or downstream of the internal ribosomal entry site, and by inserting 1 to 3 alanine residue(s) at the intracellular juxtamembrane region. As a result, while the signaling response was different among the three signalobodies, the antigen-dependent on/off regulation became tighter when the cell-surface expression levels of the signalobodies were lowered. Therefore, we successfully developed a method to diminish the leaky signaling of RTK-based signalobodies, which will be important for establishing the signalobody-based platform technology that can produce cells of interest for regenerative medicine.

Opportunities and challenges for the cellular immunotherapy sector: a global landscape of clinical trials

Global investments in cellular immunotherapies reflect their curative potential. Our landscape of clinical trials will aid developers, investors, adopters and payers in planning for adoption and implementation along realistic time horizons. Trend data enable stakeholders to adapt their business models and capacity to bring immunotherapies to the clinic. For cancer, trends suggest a shift from cancer vaccines to adoptive cellular transfer, alongside a focus on solid tumors. Academic centers, mainly in the USA, lead in early-phase clinical trials and target identification; but industry involvement has increased fourfold over the past two decades. Trends indicate an increasingly personalized approach to onco-immunology, which raises challenges for cost-effective manufacturing and delivery models. Overcoming these challenges provides opportunities for innovative biotechnology firms.

Fabrication of Innovative Silk/Alginate Microcarriers for Mesenchymal Stem Cell Delivery and Tissue Regeneration

The aim of this study was to exploit silk fibroin’s properties to develop innovative composite microcarriers for mesenchymal stem cell (MSCs) adhesion and proliferation. Alginate microcarriers were prepared, added to silk fibroin solution, and then treated with ethanol to induce silk conformational transition. Microcarriers were characterized for size distribution, coating stability and homogeneity. Finally, in vitro cytocompatibility and suitability as delivery systems for MSCs were investigated. Results indicated that our manufacturing process is consistent and reproducible: silk/alginate microcarriers were stable, with spherical geometry, about 400 μm in average diameter, and fibroin homogeneously coated the surface. MSCs were able to adhere rapidly onto the microcarrier surface and to cover the surface of the microcarrier within three days of culture; moreover, on this innovative 3D culture system, stem cells preserved their metabolic activity and their multi-lineage differentiation potential. In conclusion, silk/alginate microcarriers represent a suitable support for MSCs culture and expansion. Since it is able to preserve MSCs multipotency, the developed 3D system can be intended for cell delivery, for advanced therapy and regenerative medicine applications.

Synthetic mRNA is a more reliable tool for the delivery of DNA-targeting proteins into the cell nucleus than fusion with a protein transduction domain

Cell reprogramming requires efficient delivery of reprogramming transcription factors into the cell nucleus. Here, we compared the robustness and workload of two protein delivery methods that avoid the risk of genomic integration. The first method is based on fusion of the protein of interest to a protein transduction domain (PTD) for delivery across the membranes of target cells. The second method relies on de novo synthesis of the protein of interest inside the target cells utilizing synthetic mRNA (syn-mRNA) as a template. We established a Cre/lox reporter system in three different cell types derived from human (PANC-1, HEK293) and rat (BRIN-BD11) tissues and used Cre recombinase to model a protein of interest. The system allowed constitutive expression of red fluorescence protein (RFP), while green fluorescence protein (GFP) was expressed only after the genomic action of Cre recombinase. The efficiency of protein delivery into cell nuclei was quantified as the frequency of GFP+ cells in the total cell number. The PTD method showed good efficiency only in BRIN-BD11 cells (68%), whereas it failed in PANC-1 and HEK293 cells. By contrast, the syn-mRNA method was highly effective in all three cell types (29-71%). We conclude that using synthetic mRNA is a more robust and less labor-intensive approach than using the PTD-fusion alternative.

Synthesis Strategies to Extend the Variety of Alginate-Based Hybrid Hydrogels for Cell Microencapsulation

The production of hydrogel microspheres (MS) for cell immobilization, maintaining the favorable properties of alginate gels but presenting enhanced performance in terms of in vivo durability and physical properties, is desirable to extend the therapeutic potential of cell transplantation. A novel type of hydrogel MS was produced by straightforward functionalization of sodium alginate (Na-alg) with heterotelechelic poly(ethylene glycol) (PEG) derivatives equipped with either end thiol or 1,2-dithiolane moieties. Activation of the hydroxyl moieties of the alginate backbone in the form of imidazolide intermediate allowed for fast conjugation to PEG oligomers through a covalent carbamate linkage. Evaluation of the modified alginates for the preparation of MS combining fast ionic gelation ability of the alginate carboxylate groups and slow covalent cross-linking provided by the PEG-end functionalities highlighted the influence of the chemical composition of the PEG-grafting units on the physical characteristics of the MS. The mechanical properties of the MS (resistance and shape recovery) and durability of PEG-grafted alginates in physiological environment can be adjusted by varying the nature of the end functionalities and the length of the PEG chains. In vitro cell microencapsulation studies and preliminary in vivo assessment suggested the potential of these hydrogels for cell transplantation applications.

Biomanufacturing of Therapeutic Cells: State of the Art, Current Challenges, and Future Perspectives

Stem cells and other functionally defined therapeutic cells (e.g., T cells) are promising to bring hope of a permanent cure for diseases and disorders that currently cannot be cured by conventional drugs or biological molecules. This paradigm shift in modern medicine of using cells as novel therapeutics can be realized only if suitable manufacturing technologies for large-scale, cost-effective, reproducible production of high-quality cells can be developed. Here we review the state of the art in therapeutic cell manufacturing, including cell purification and isolation, activation and differentiation, genetic modification, expansion, packaging, and preservation. We identify current challenges and discuss opportunities to overcome them such that cell therapies become highly effective, safe, and predictively reproducible while at the same time becoming affordable and widely available.

Adaptation through Collaboration: Developing Novel Platforms to Advance the Delivery of Advanced Therapies to Patients

For the nascent field of advanced therapies, collaboration will be a game-changer, turning scientific progress that was once unimaginable into transformative medical practice. Despite promise for lifelong management and even cure of disease, skepticism remains about the feasibility of their delivery to patients, fueling investment risks. With the potential for long-term effectiveness in need of frequent reassessment, current approaches to predict real-life drug performance bear little relevance, necessitating novel and iterative schemes to monitoring the benefit–risk profiles throughout the life span of advanced therapies. This work explains that reinventing an adoption route for Advanced Therapy Medicinal Products is as much about the scientific and clinical components, as it is about the organizational structures, requiring an unprecedented level of interactions between stakeholders not traditionally connected; from developers and regulators, to payers, patients, and funders. By reflecting on the successes and lessons learned from the growing space of global precompetitive consortia and public–private partnerships, as well as a number of emerging accelerated development pathways, this work aims to inform the foundations for a future roadmap that can smooth the path to approval, reimbursement, and access, while delivering value to all stakeholders. Echoing the growing demands to bring these transformative products to patients, it provides critical insights to enhance our capacity in three fundamental domains: deploying the operational flexibilities offered by the growing space of collaborations, utilizing emerging flexible and accelerated pathways to tackle challenges in quantifying long-term effectiveness, and building the necessary digital and clinical infrastructure for knowledge development.

IL233, A Novel IL-2 and IL-33 Hybrid Cytokine, Ameliorates Renal Injury

CD4⁺Foxp3⁺ regulatory T cells (Tregs) protect the kidney during AKI. We previously found that IL-2, which is critical for Treg homeostasis, upregulates the IL-33 receptor (ST2) on CD4⁺ T cells, thus we hypothesized that IL-2 and IL-33 cooperate to enhance Treg function. We found that a major subset of Tregs in mice express ST2, and coinjection of IL-2 and IL-33 increased the number of Tregs in lymphoid organs and protected mice from ischemia-reperfusion injury (IRI) more efficiently than either cytokine alone. Accordingly, we generated a novel hybrid cytokine (IL233) bearing the activities of IL-2 and IL-33 for efficient targeting to Tregs. IL233 treatment increased the number of Tregs in blood and spleen and prevented IRI more efficiently than a mixture of IL-2 and IL-33. Injection of IL233 also increased the numbers of Tregs in renal compartments. Moreover, IL233-treated mice had fewer splenic Tregs and more Tregs in kidneys after IRI. In vitro, splenic Tregs from IL233-treated mice suppressed CD4⁺ T cell proliferation better than Tregs from saline-treated controls. IL233 treatment also improved the ability of isolated Tregs to inhibit IRI in adoptive transfer experiments and protected mice from cisplatin- and doxorubicin-induced nephrotoxic injury. Finally, treatment with IL233 increased the proportion of ST2-bearing innate lymphoid cells (ILC2) in blood and kidneys, and adoptive transfer of ILC2 also protected mice from IRI. Thus, the novel IL233 hybrid cytokine, which utilizes the cooperation of IL-2 and IL-33 to enhance Treg- and ILC2-mediated protection from AKI, bears strong therapeutic potential.

Clinical-scale expansion of adipose-derived stromal cells starting from stromal vascular fraction in a single-use bioreactor: proof of concept for autologous applications

Adipose-derived stromal cells (ASCs) are adult multipotent cells increasingly used for cell therapy due to their differentiation potential, their paracrine effect and their convenience. ASCs are currently selected from stromal vascular fractions (SVFs) of adipose tissue and expanded in 2D flasks following good manufacturing practices. This process is limited in surface area, labour-intensive and expensive, especially for autologous applications requiring selection and expansion steps for every patient. Closed and automated bioreactors offer an alternative for scalable and cost-effective production of ASCs. This study investigated a single-use stirred-tank bioreactor that can expand ASCs from SVFs on microcarriers. A preliminary microcarrier screening in static and spinner flask conditions was performed to evaluate the best candidate for adhesion, amplification and harvest. The selected microcarrier was used for process development in the bioreactor. The first experiments showed poor selectivity and growth of the ASCs from the SVF (n  =  2). The process was then adjusted by two means: (1) decreasing the platelet lysate in the medium for enhancing cell adherence; and (2) adding a shear protectant (Pluronic F68). Following these modifications, we demonstrated that the number of population doublings of ASCs from SVFs was not significantly different between the bioreactor and the 2D controls (n  =  3). In addition, the ASC characterization after culture showed that cells maintained their clonogenic potential, phenotype, differentiation potential and immunosuppressive capacities. This study provides the proof of concept that isolation and amplification of functional ASCs from SVFs can be performed in a stirred-tank bioreactor combined with microcarriers. Copyright © 2016 John Wiley & Sons, Ltd.

Responsible Translation of Stem Cell Research: An Assessment of Clinical Trial Registration and Publications

We assessed the extent to which the publication of clinical trial results of innovative cell-based interventions reflects International Society for Stem Cell Research best practice guidelines. We assessed: (1) characteristics and time to publication of completed trials; (2) quality of reported trials; and (3) results of published trials. We identified and analyzed publications from 1,052 novel stem cell clinical trials: 179 (45.4%) of 393 completed trials had published results; 48 trials were registered by known stem cell tourism clinics, none of which reported results. Completed non-industry-sponsored trials initially published more rapidly, but differences with industry-sponsored trials decreased over time. Most publications reported safety, and 67.3% (mainly early-stage trials) reported positive outcomes. A higher proportion of industry trials reported positive efficacy. Heightened patient expectations for stem cell therapies give rise to ethical obligations for the transparent conduct of clinical trials. Reporting guidelines need to be developed that are specific to early-phase clinical trials.

Innovative regenerative medicines in the EU: a better future in evidence?

BACKGROUND

Despite a steady stream of headlines suggesting they will transform the future of healthcare, high-tech regenerative medicines have, to date, been quite inaccessible to patients, with only eight having been granted an EU marketing licence in the last 7 years. Here, we outline some of the historical reasons for this paucity of licensed innovative regenerative medicines. We discuss the challenges to be overcome to expedite the development of this complex and rapidly changing area of medicine, together with possible reasons to be more optimistic for the future.

DISCUSSION

Several factors have contributed to the scarcity of cutting-edge regenerative medicines in clinical practice. These include the great expense and difficulties involved in planning how individual therapies will be developed, manufactured to commercial levels and ultimately successfully delivered to patients. Specific challenges also exist when evaluating the safety, efficacy and cost-effectiveness of these therapies. Furthermore, many treatments are used without a licence from the European Medicines Agency, under "Hospital Exemption" from the EC legislation. For products which are licensed, alternative financing approaches by healthcare providers may be needed, since many therapies will have significant up-front costs but uncertain benefits and harms in the long-term. However, increasing political interest and more flexible mechanisms for licensing and financing of therapies are now evident; these could be key to the future growth and development of regenerative medicine in clinical practice.

CONCLUSIONS

Recent developments in regulatory processes, coupled with increasing political interest, may offer some hope for improvements to the long and often difficult routes from laboratory to marketplace for leading-edge cell or tissue therapies. Collaboration between publicly-funded researchers and the pharmaceutical industry could be key to the future development of regenerative medicine in clinical practice; such collaborations might also offer a possible antidote to the innovation crisis in the pharmaceutical industry.

Rewiring human cellular input-output using modular extracellular sensors

Engineered cell-based therapies comprise a promising emerging strategy for treating diverse diseases. Realizing this promise requires new tools for engineering cells to sense and respond to soluble extracellular factors, which provide information about both physiological state and the local environment. Here, we report such a biosensor engineering strategy, leveraging a self-contained receptor-signal transduction system termed modular extracellular sensor architecture (MESA). We developed MESA receptors that enable cells to sense vascular endothelial growth factor (VEGF) and, in response, secrete interleukin 2 (IL-2). By implementing these receptors in human T cells, we created a customized function not observed in nature-an immune cell that responds to a normally immunosuppressive cue (VEGF) by producing an immunostimulatory factor (IL-2). Because this platform utilizes modular, engineerable domains for ligand binding (antibodies) and output (programmable transcription factors based upon Cas9), this approach may be readily extended to novel inputs and outputs. This generalizable approach for rewiring cellular functions could enable both translational applications and fundamental biological research.

An Integrated Miniature Bioprocessing for Personalized Human Induced Pluripotent Stem Cell Expansion and Differentiation into Neural Stem Cells

Human induced pluripotent stem cells (iPSCs) are ideal cell sources for personalized cell therapies since they can be expanded to generate large numbers of cells and differentiated into presumably all the cell types of the human body in vitro. In addition, patient specific iPSC-derived cells induce minimal or no immune response in vivo. However, with current cell culture technologies and bioprocessing, the cost for biomanufacturing clinical-grade patient specific iPSCs and their derivatives are very high and not affordable for majority of patients. In this paper, we explored the use of closed and miniature cell culture device for biomanufacturing patient specific neural stem cells (NSCs) from iPSCs. We demonstrated that, with the assist of a thermoreversible hydrogel scaffold, the bioprocessing including iPSC expansion, iPSC differentiation into NSCs, the subsequent depletion of undifferentiated iPSCs from the NSCs, and concentrating and transporting the purified NSCs to the surgery room, could be integrated and completed within two closed 15 ml conical tubes.

LL-37 boosts immunosuppressive function of placenta-derived mesenchymal stromal cells

BACKGROUND

Although promising for graft-versus-host disease (GvHD) treatment, MSC therapy still faces important challenges. For instance, increasing MSC migratory capacity as well as potentializing immune response suppression are of interest. For GvHD management, preventing opportunistic infections is also a valuable strategy, since immunocompromised patients are easy targets for infections. LL-37 is a host defense peptide (HDP) that has been deeply investigated due to its immunomodulatory function. In this scenario, the combination of MSC and LL-37 may result in a robust combination to be clinically used.

METHODS

In the present study, the effects of LL-37 upon the proliferation and migratory capacity of human placenta-derived MSCs (pMSCs) were assessed by MTT and wound scratch assays. The influence of LL-37 over the immunosuppressive function of pMSCs was then investigated using CFSE cell division kit. Flow cytometry and real-time PCR were used to investigate the molecular mechanisms involved in the effects observed.

RESULTS

LL-37 had no detrimental effects over MSC proliferation and viability, as assessed by MTT assay. Moreover, the peptide promoted increased migratory behavior of pMSCs and enhanced their immunomodulatory function over activated human PBMCs. Strikingly, our data shows that LL-37 treatment leads to increased TLR3 levels, as shown by flow cytometry, and to an increased expression of factors classically related to immunosuppression, namely IDO, IL-10, TGF-β, IL-6, and IL-1β.

CONCLUSIONS

Taken together, our observations may serve as groundwork for the development of new therapeutic strategies based on the combined use of LL-37 and MSCs, which may provide patients not only with an enhanced immunosuppression regime, but also with an agent to prevent opportunistic infections.

Uncertainty and innovation: Understanding the role of cell-based manufacturing facilities in shaping regulatory and commercialization environments

The purpose of this qualitative study is to elucidate stakeholder perceptions of, and institutional practices related to cell-based therapies and products (CTP) regulation and commercialization in Canada. The development of reproducible, safe and effective CTPs is predicated on regulatory and commercialization environments that enable innovation. Manufacturing processes constitute a critical step for CTP development in this regard. The road from CTP manufacturing to translation in the clinic, however, has yet to be paved. This study aims to fill an empirical gap in the literature by exploring how CTP manufacturing facilities navigate Canadian regulatory and commercialization environments, which together drive the translation of novel CTPs from bench to bedside. Using the multi-level model of practice-driven institutional change proposed by Smets et al., we demonstrate how CTP manufacturing practices are governed by established standards, yet meaningfully shape higher-order regulatory and commercial norms in CTP research and development. We identify four key themes that undergird such processes of innovation: 1) managing regulatory uncertainty, which stems from an inability to classify CTPs within existing regulatory categories for approval and commercialization purposes; 2) building a 'business case' whereby a CTP's market potential is determined in large part by proving its safety and effectiveness; 3) standardizing manufacturing procedures that mobilize CTPs from a research and development phase to a commercialization one; and 4) networking between researchers and regulators to develop responsible commercialization processes that reflect the uniqueness of CTPs as distinct from other biologics and medical devices.

Red blood cells: Supercarriers for drugs, biologicals, and nanoparticles and inspiration for advanced delivery systems

Red blood cells (RBCs) constitute a unique drug delivery system as a biologic or hybrid carrier capable of greatly enhancing pharmacokinetics, altering pharmacodynamics (for example, by changing margination within the intravascular space), and modulating immune responses to appended cargoes. Strategies for RBC drug delivery systems include internal and surface loading, and the latter can be performed both ex vivo and in vivo. A relatively new avenue for RBC drug delivery is their application as a carrier for nanoparticles. Efforts are also being made to incorporate features of RBCs in nanocarriers to mimic their most useful aspects, such as long circulation and stealth features. RBCs have also recently been explored as carriers for the delivery of antigens for modulation of immune response. Therefore, RBC-based drug delivery systems represent supercarriers for a diverse array of biomedical interventions, and this is reflected by several industrial and academic efforts that are poised to enter the clinical realm.

Tools and applications in synthetic biology

Advances in synthetic biology have enabled the engineering of cells with genetic circuits in order to program cells with new biological behavior, dynamic gene expression, and logic control. This cellular engineering progression offers an array of living sensors that can discriminate between cell states, produce a regulated dose of therapeutic biomolecules, and function in various delivery platforms. In this review, we highlight and summarize the tools and applications in bacterial and mammalian synthetic biology. The examples detailed in this review provide insight to further understand genetic circuits, how they are used to program cells with novel functions, and current methods to reliably interface this technology in vivo; thus paving the way for the design of promising novel therapeutic applications.

Secreted trophic factors of mesenchymal stem cells support neurovascular and musculoskeletal therapies

Adult mesenchymal stem cells (MSCs) represent a subject of intense experimental and biomedical interest. Recently, trophic activities of MSCs have become the topic of a number of revealing studies that span both basic and clinical fields. In this review, we focus on recent investigations that have elucidated trophic mechanisms and shed light on MSC clinical efficacy relevant to musculoskeletal applications. Innate differences due to MSC sourcing may play a role in the clinical utility of isolated MSCs. Pain management, osteochondral, nerve, or blood vessel support by MSCs derived from both autologous and allogeneic sources have been examined. Recent mechanistic insights into the trophic activities of these cells point to ultimate regulation by nitric oxide, nuclear factor-kB, and indoleamine, among other signaling pathways. Classic growth factors and cytokines-such as VEGF, CNTF, GDNF, TGF-β, interleukins (IL-1β, IL-6, and IL-8), and C-C ligands (CCL-2, CCL-5, and CCL-23)-serve as paracrine control molecules secreted or packaged into extracellular vesicles, or exosomes, by MSCs. Recent studies have also implicated signaling by microRNAs contained in MSC-derived exosomes. The response of target cells is further regulated by their microenvironment, involving the extracellular matrix, which may be modified by MSC-produced matrix metalloproteinases (MMPs) and tissue inhibitor of MMPs. Trophic activities of MSCs, either resident or introduced exogenously, are thus intricately controlled, and may be further fine-tuned via implant material modifications. MSCs are actively being investigated for the repair and regeneration of both osteochondral and other musculoskeletal tissues, such as tendon/ligament and meniscus. Future rational and effective MSC-based musculoskeletal therapies will benefit from better mechanistic understanding of MSC trophic activities, for example using analytical "-omics" profiling approaches.

Scalable microcarrier-based manufacturing of mesenchymal stem/stromal cells

Due to their unique features, mesenchymal stem/stromal cells (MSC) have been exploited in clinical settings as therapeutic candidates for the treatment of a variety of diseases. However, the success in obtaining clinically-relevant MSC numbers for cell-based therapies is dependent on efficient isolation and ex vivo expansion protocols, able to comply with good manufacturing practices (GMP). In this context, the 2-dimensional static culture systems typically used for the expansion of these cells present several limitations that may lead to reduced cell numbers and compromise cell functions. Furthermore, many studies in the literature report the expansion of MSC using fetal bovine serum (FBS)-supplemented medium, which has been critically rated by regulatory agencies. Alternative platforms for the scalable manufacturing of MSC have been developed, namely using microcarriers in bioreactors, with also a considerable number of studies now reporting the production of MSC using xenogeneic/serum-free medium formulations. In this review we provide a comprehensive overview on the scalable manufacturing of human mesenchymal stem/stromal cells, depicting the various steps involved in the process from cell isolation to ex vivo expansion, using different cell tissue sources and culture medium formulations and exploiting bioprocess engineering tools namely microcarrier technology and bioreactors.

Large-scale progenitor cell expansion for multiple donors in a monitored hollow fibre bioreactor

BACKGROUND AIMS

With the increasing scale in stem cell production, a robust and controlled cell expansion process becomes essential for the clinical application of cell-based therapies. The objective of this work was the assessment of a hollow fiber bioreactor (Quantum Cell Expansion System from Terumo BCT) as a cell production unit for the clinical-scale production of human periosteum derived stem cells (hPDCs).

METHODS

We aimed to demonstrate comparability of bioreactor production to standard culture flask production based on a product characterization in line with the International Society of Cell Therapy in vitro benchmarks and supplemented with a compelling quantitative in vivo bone-forming potency assay. Multiple process read-outs were implemented to track process performance and deal with donor-to-donor-related variation in nutrient needs and harvest timing.

RESULTS

The data show that the hollow fiber bioreactor is capable of robustly expanding autologous hPDCs on a clinical scale (yield between 316 million and 444 million cells starting from 20 million after ± 8 days of culture) while maintaining their in vitro quality attributes compared with the standard flask-based culture. The in vivo bone-forming assay on average resulted in 10.3 ± 3.7% and 11.0 ± 3.8% newly formed bone for the bioreactor and standard culture flask respectively. The analysis showed that the Quantum system provides a reproducible cell expansion process in terms of yields and culture conditions for multiple donors.

Clinical manufacturing of CAR T cells: foundation of a promising therapy

The treatment of cancer patients with autologous T cells expressing a chimeric antigen receptor (CAR) is one of the most promising adoptive cellular therapy approaches. Reproducible manufacturing of high-quality, clinical-grade CAR-T cell products is a prerequisite for the wide application of this technology. Product quality needs to be built-in within every step of the manufacturing process. We summarize herein the requirements and logistics to be considered, as well as the state of the art manufacturing platforms available. CAR-T cell therapy may be on the verge of becoming standard of care for a few clinical indications. Yet, many challenges pertaining to manufacturing standardization and product characterization remain to be overcome in order to achieve broad usage and eventual commercialization of this therapeutic modality.

Rapid and efficient magnetization of mesenchymal stem cells by dendrimer-functionalized magnetic nanoparticles

Aim: Rapid and efficient magnetization of human bone marrow stromal cells (BMSC) through functionalized magnetic nanoparticles (MNP). Methods: MNP were functionalized with poly(epsilon-lysine) dendrons exposing carboxybetaine residue (CB-MNP) to enhance binding to the cellular glycocalix. BMSC were incubated with CB-MNP or non-functionalized PAA-MNP for 5–30 min in suspension. Results: CB-MNP functionalization increased the magnetization efficiency by threefold. Remarkably, 66% of cells were magnetized after only 5 min and the maximum efficiency of >80% was reached by 15 min. BMSC viability, proliferation and differentiation were not impaired: actually, adipogenic and osteogenic differentiation were even improved. Conclusion: Carboxybetaine-dendron functionalization ensured rapid and efficient BMSC magnetization and allowed innovative suspension labeling, with a potential for bypassing adhesion culture of progenitors for regenerative medicine.

Serum-free process development: improving the yield and consistency of human mesenchymal stromal cell production

BACKGROUND AIMS

The cost-effective production of human mesenchymal stromal cells (hMSCs) for off-the-shelf and patient specific therapies will require an increasing focus on improving product yield and driving manufacturing consistency.

METHODS

Bone marrow-derived hMSCs (BM-hMSCs) from two donors were expanded for 36 days in monolayer with medium supplemented with either fetal bovine serum (FBS) or PRIME-XV serum-free medium (SFM). Cells were assessed throughout culture for proliferation, mean cell diameter, colony-forming potential, osteogenic potential, gene expression and metabolites.

RESULTS

Expansion of BM-hMSCs in PRIME-XV SFM resulted in a significantly higher growth rate (P < 0.001) and increased consistency between donors compared with FBS-based culture. FBS-based culture showed an inter-batch production range of 0.9 and 5 days per dose compared with 0.5 and 0.6 days in SFM for each BM-hMSC donor line. The consistency between donors was also improved by the use of PRIME-XV SFM, with a production range of 0.9 days compared with 19.4 days in FBS-based culture. Mean cell diameter has also been demonstrated as a process metric for BM-hMSC growth rate and senescence through a correlation (R(2) = 0.8705) across all conditions. PRIME-XV SFM has also shown increased consistency in BM-hMSC characteristics such as per cell metabolite utilization, in vitro colony-forming potential and osteogenic potential despite the higher number of population doublings.

CONCLUSIONS

We have increased the yield and consistency of BM-hMSC expansion between donors, demonstrating a level of control over the product, which has the potential to increase the cost-effectiveness and reduce the risk in these manufacturing processes.

Theoretical and Practical Issues That Are Relevant When Scaling Up hMSC Microcarrier Production Processes

The potential of human mesenchymal stem cells (hMSCs) for allogeneic cell therapies has created a large amount of interest. However, this presupposes the availability of efficient scale-up procedures. Promising results have been reported for stirred bioreactors that operate with microcarriers. Recent publications focusing on microcarrier-based stirred bioreactors have demonstrated the successful use of Computational Fluid Dynamics (CFD) and suspension criteria (N S1u , N S1) for rapidly scaling up hMSC expansions from mL- to pilot scale. Nevertheless, one obstacle may be the formation of large microcarrier-cell-aggregates, which may result in mass transfer limitations and inhomogeneous distributions of stem cells in the culture broth. The dependence of microcarrier-cell-aggregate formation on impeller speed and shear stress levels was investigated for human adipose derived stromal/stem cells (hASCs) at the spinner scale by recording the Sauter mean diameter (d 32) versus time. Cultivation at the suspension criteria provided d 32 values between 0.2 and 0.7 mm, the highest cell densities (1.25 × 10(6) cells mL(-1) hASCs), and the highest expansion factors (117.0 ± 4.7 on day 7), while maintaining the expression of specific surface markers. Furthermore, suitability of the suspension criterion N S1u was investigated for scaling up microcarrier-based processes in wave-mixed bioreactors for the first time.

New cell sources for T cell engineering and adoptive immunotherapy

The promising clinical results obtained with engineered T cells, including chimeric antigen receptor (CAR) therapy, call for further advancements to facilitate and broaden their applicability. One potentially beneficial innovation is to exploit new T cell sources that reduce the need for autologous cell manufacturing and enable cell transfer across histocompatibility barriers. Here we review emerging T cell engineering approaches that utilize alternative T cell sources, which include virus-specific or T cell receptor-less allogeneic T cells, expanded lymphoid progenitors, and induced pluripotent stem cell (iPSC)-derived T lymphocytes. The latter offer the prospect for true off-the-shelf, genetically enhanced, histocompatible cell therapy products.