Current challenges in cell and gene therapy: a joint view from the European Committee of the International Society for Cell & Gene Therapy (ISCT) and the European Society for Blood and Marrow Transplantation (EBMT).

Cell and gene therapy poses evolving challenges. The current article summarizes the discussions held by European Regional Committee of the International Society for Cell & Gene Therapy and the European Society for Blood and Marrow Transplantation (EBMT) on the current challenges in this field, focusing on the European setting. This article emphasizes the imperative assessment of real-world cell and gene therapy activity, advocating for expanded registries beyond hematopoietic transplantation and chimeric antigen receptor-T-cell therapy. Accreditation's role in ensuring standardized procedures, as exemplified by JACIE (The Joint Accreditation Committee of ISCT-Europe and EBMT), is crucial for safety. Access to commercial products and reimbursement variations among countries underscore the need for uniform access to advanced therapy medical products (ATMPs). Academic product development and point-of-care manufacturing face barriers to patient access. Hospital Exemption's potential, demonstrated by some initial experiences, may increase patient accessibility in individual situations. Regulatory challenges, including the ongoing European ATMPs legislation review, necessitate standardized criteria for Hospital Exemption and mandatory reporting within registries. Efforts to combat unproven therapies and fraud involve collaboration between scientific societies, regulatory bodies and patient groups. Finally, is important to highlight the vital role of education and workforce development in meeting the escalating demand for specialized professionals in the ATMP field. Collaboration among scientific societies, academic institutions, industry, regulatory bodies and patient groups is crucial for overcoming all these challenges to increase gene and cell therapy activity in Europe.

Human Wharton's jelly-derived mesenchymal stromal cells promote bone formation in immunodeficient mice when administered into a bone microenvironment.

BACKGROUND: Wharton's Jelly (WJ) Mesenchymal Stromal Cells (MSC) have emerged as an attractive allogeneic therapy for a number of indications, except for bone-related conditions requiring new tissue formation. This may be explained by the apparent recalcitrance of MSC,WJ to differentiate into the osteogenic lineage in vitro, as opposed to permissive bone marrow (BM)-derived MSCs (MSC,BM) that readily commit to bone cells. Consequently, the actual osteogenic in vivo capacity of MSC,WJ is under discussion. METHODS: We investigated how physiological bone environments affect the osteogenic commitment of recalcitrant MSCs in vitro and in vivo. To this end, MSC of BM and WJ origin were co-cultured and induced for synchronous osteogenic differentiation in vitro using transwells. For in vivo experiments, immunodeficient mice were injected intratibially with a single dose of human MSC and bone formation was evaluated after six weeks. RESULTS: Co-culture of MSC,BM and MSC,WJ resulted in efficient osteogenesis in both cell types after three weeks. However, MSC,WJ failed to commit to bone cells in the absence of MSC,BM's osteogenic stimuli. In vivo studies showed successful bone formation within the medullar cavity of tibias in 62.5% of mice treated with MSC, WJ. By contrast, new formed trabeculae were only observed in 25% of MSC,BM-treated mice. Immunohistochemical staining of human COXIV revealed the persistence of the infused cells at the site of injection. Additionally, cells of human origin were also identified in the brain, heart, spleen, kidney and gonads in some animals treated with engineered MSC,WJ (eMSC,WJ). Importantly, no macroscopic histopathological alterations, ectopic bone formation or any other adverse events were detected in MSC-treated mice. CONCLUSIONS: Our findings demonstrate that in physiological bone microenvironment, osteogenic commitment of MSC,WJ is comparable to that of MSC,BM, and support the use of off-the-shelf allogeneic MSC,WJ products in bone repair and bone regeneration applications.

Cell and gene therapy workforce development: the role of the International Society for Cell & Gene Therapy (ISCT) in the creation of a sustainable and skilled workforce in Europe.

The development and production of cell gene and tissue (CGT)-based therapies requires a specialized workforce. Entering the CGT arena is complex because it involves different scientific and biomedical aspects (e.g., immunology, stem cell biology and transplantation), as well as knowledge of regulatory affairs and compliance with pharmaceutical quality standards. Currently, both industry and academia are facing a worldwide workforce shortage, whereas only a handful of educational and training initiatives specifically address the peculiarities of CGT product development, the procurement of substances of human origin, the manufacturing process itself and clinical monitoring and biovigilance. The training offered by traditional Master's and PhD programs is not suited for training a skilled workforce ready to enter the increasingly fast-growing CGT field. Indeed, typically these programs are of long duration and only partially cover the required competencies, whereas the demand for a specialized workforce relentlessly increases. In this paper, we (i) present and discuss our understanding of the roots of current growth acceleration of the CGT field; (ii) anticipate future workforce needs due to the expected increase of marketed CGT-based therapies and (iii) evaluate potential solutions that seek to adapt, develop and implement current educational and training initiatives. Importantly for these solutions, we call for scientific societies, such as the International Society for Cell & Gene Therapy, to play a more active role and act as catalysers for new initiatives, building bridges between academia and Industry to establish effective educational and training programs that will engage and prepare a new generation of qualified professionals for entry into the CGT field.

Comparability exercise of critical quality attributes of clinical-grade human mesenchymal stromal cells from the Wharton's jelly: single-use stirred tank bioreactors versus planar culture systems.

BACKGROUND AIMS: The increasing demand of clinical-grade mesenchymal stromal cells (MSCs) for use in advanced therapy medicinal products (ATMPs) require a re-evaluation of manufacturing strategies, ensuring scalability from two-dimensional (2D) surfaces to volumetric (3D) productivities. Herein we describe the design and validation of a Good Manufacturing Practice-compliant 3D culture methodology using microcarriers and 3-L single-use stirred tank bioreactors (STRs) for the expansion of Wharton's jelly (WJ)-derived MSCs in accordance to current regulatory and quality requirements. METHODS: MSC,WJ were successfully expanded in 3D and final product characterization was in conformity with Critical Quality Attributes and product specifications previously established for 2D expansion conditions. RESULTS: After 6 days of culture, cell yields in the final product from the 3D cultures (mean 9.48 × 108 ± 1.07 × 107 cells) were slightly lower but comparable with those obtained from 2D surfaces (mean 9.73 × 108 ± 2.36 × 108 cells) after 8 days. In all analyzed batches, viability was >90%. Immunophenotype of MSC,WJ was highly positive for CD90 and CD73 markers and lacked of expression of CD31, CD45 and HLA-DR. Compared with 2D expansions, CD105 was detected at lower levels in 3D cultures due to the harvesting procedure from microcarriers involving trypsin at high concentration, and this had no impact on multipotency. Cells presented normal karyotype and strong immunomodulatory potential in vitro. Sterility, Mycoplasma, endotoxin and adventitious virus were negative in both batches produced. CONCLUSIONS: In summary, we demonstrated the establishment of a feasible and reproducible 3D bioprocess using single-use STR for clinical-grade MSC,WJ production and provide evidence supporting comparability of 3D versus 2D production strategies. This comparability exercise evaluates the direct implementation of using single-use STR for the scale-up production of MSC,WJ and, by extension, other cell types intended for allogeneic therapies.

A management model in blood, tissue and cell establishments to ensure rapid and sustainable patient access to advanced therapy medicinal products in Europe.

Blood, tissue and cell establishments (BTCs) stand out in the management of donor selection, procurement and processing of all types of substances of human origin (SoHO). In the last decades, the framework created around BTCs, including hospitals and national health system networks, and their links to research, development and innovation organizations and agencies have spurred their involvement in the study of groundbreaking advanced therapy medicinal products (ATMP). To further improve strategic synergies in the development of ATMPs, it will be required to promote intra- and inter-European collaborations by creating an international network involving BTCs and major stakeholders (i.e., research organizations, hospitals, universities, patient associations, public agencies). This vision is already shared with the European Blood Alliance, the association of non-profit blood establishments, with 26 member states throughout the European Union and European Free Trade Association states. Herein we present and analyze the "BTC for ATMP Development And Manufacture" (BADAM) model, an ethically responsible business model based on the values and missions of BTCs and their commitment to health equity, patient access and education (based on voluntary donation of SoHO to address unmet clinical needs, while contributing to training professionals and scientific literacy of our Society).

A hub-and-spoke model to deliver effective access to chimeric antigen receptor T-cell therapy in a public health network: the Catalan Blood and Tissue Bank experience.

BACKGROUND AIMS: To describe and analyze whether a hub-and-spoke organizational model could efficiently provide access to chimeric antigen receptor (CAR) T-cell therapy within a network of academic hospitals and address the growing demands of this complex and specialized activity. METHODS: The authors performed a retrospective evaluation of activity within the Catalan Blood and Tissue Bank network, which was established for hematopoietic stem cell transplantation to serve six CAR T-cell programs in academic hospitals of the Catalan Health Service. Procedures at six hospitals were followed from 2016 to 2021. Collection shipments of starting materials, CAR T-cell returns for storage and infusions for either clinical trials or commercial use were evaluated. RESULTS: A total of 348 leukocytapheresis procedures were performed, 39% of which were delivered fresh and 61% of which were cryopreserved. The network was linked to seven advanced therapy medicinal product manufacturers. After production, 313 CAR T-cell products were shipped back to the central cryogenic medicine warehouse located in the hub. Of the units received, 90% were eventually administered to patients. A total of 281 patients were treated during this period, 45% in clinical trials and the rest with commercially available CAR T-cell therapies. CONCLUSIONS: A hub-and-spoke organizational model based on an existing hematopoietic stem cell transplantation program is efficient in incorporating CAR T-cell therapy into a public health hospital network. Rapid access and support of growing activity enabled 281 patients to receive CAR T cells during the study period.

Preservation of critical quality attributes of mesenchymal stromal cells in 3D bioprinted structures by using natural hydrogel scaffolds.

Three dimensional (3D) bioprinting is an emerging technology that enables complex spatial modeling of cell-based tissue engineering products, whose therapeutic potential in regenerative medicine is enormous. However, its success largely depends on the definition of a bioprintable zone, which is specific for each combination of cell-loaded hydrogels (or bioinks) and scaffolds, matching the mechanical and biological characteristics of the target tissue to be repaired. Therefore proper adjustment of the bioink formulation requires a compromise between: (i) the maintenance of cellular critical quality attributes (CQA) within a defined range of specifications to cell component, and (ii) the mechanical characteristics of the printed tissue to biofabricate. Herein, we investigated the advantages of using natural hydrogel-based bioinks to preserve the most relevant CQA in bone tissue regeneration applications, particularly focusing on cell viability and osteogenic potential of multipotent mesenchymal stromal cells (MSCs) displaying tripotency in vitro, and a phenotypic profile of 99.9% CD105+ /CD45,- 10.3% HLA-DR,+ 100.0% CD90,+ and 99.2% CD73+ /CD31- expression. Remarkably, hyaluronic acid, fibrin, and gelatin allowed for optimal recovery of viable cells, while preserving MSC's proliferation capacity and osteogenic potency in vitro. This was achieved by providing a 3D structure with a compression module below 8.8 ± 0.5 kPa, given that higher values resulted in cell loss by mechanical stress. Beyond the biocompatibility of naturally occurring polymers, our results highlight the enhanced protection on CQA exerted by bioinks of natural origin (preferably HA, gelatin, and fibrin) on MSC, bone marrow during the 3D bioprinting process, reducing shear stress and offering structural support for proliferation and osteogenic differentiation.

Potency Assays: The 'Bugaboo' of Stem Cell Therapy.

Substantially manipulated cell-based products for human use are considered medicines and therefore regulatory authorities require extensive characterisation in terms of identity, purity and potency. The latter critical quality attribute is probably the most challenging to identify and measure, requiring provision that potency assays should reflect the intended mechanism of action and demonstrate the drugs' biological effect. However, in most cases, the mechanisms involved are not fully understood, making the definition and validation of suitable potency tests difficult, a 'bugaboo' quest to be feared. Although it is evident that much work is still needed in the scientific arena, the present chapter focuses on strategies currently used by developers of cell- and gene-based therapies to demonstrate potency of innovative medicines, the regulatory framework and need for standardisation seeking to demystify critical factors to consider when designing a potency assay.

Illustrative Potency Assay Examples from Approved Therapies.

Advanced therapy medicinal products (ATMP) encompass a new type of drugs resulting from the manipulation of genes, cells, and tissues to generate innovative medicinal entities with tailored pharmaceutical activity. Definition of suitable potency tests for product release are challenging in this context, in which the active ingredient is composed of living cells and the mechanism of action often is poorly understood. In this chapter, we present and discuss actual potency assays used for the release of representative commercial ATMP from each category of products (namely, KYMRIAH® (tisagenlecleucel), Holoclar® (limbal epithelial stem cells), and PROCHYMAL®/RYONCIL™ (remestemcel-L)). We also examine concerns related to the biological relevance of selected potency assays and challenges ahead for harmonization and broader implementation in compliance with current quality standards and regulatory guidelines.

Optimisation of processing methods to improve success in the derivation of human multipotent mesenchymal stromal cells from cryopreserved umbilical cord tissue fragments.

Wharton's Jelly (WJ)-derived Mesenchymal Stromal Cells (MSC) are currently in the spotlight for the development of innovative MSC-based therapies due to their ease of sourcing, high proliferation capacity and improved immunopotency over MSC from other tissue sources. However, the short time window for derivation from donated fresh umbilical cord (UC) tissue fragments does not allow to consider biological features of the donor beyond serological safety testing. This limits the scope of MSC banking to rapid, prospective derivation of MSC, WJ lines without considering biological and genetic characteristics of the donor that may influence their suitability for clinical use (e.g. HLA type, inherited gene variants). In the present study, we describe a simple, efficient and reproducible approach for the cryopreservation of UC tissue fragments, compatible with established workflows in existing public frameworks for cord blood and tissue collection while guaranteeing pharmaceutical grade of starting materials for further processing under GMP standards. Herein we demonstrated the feasibility of time and cost-saving methods for cryopreservation of unprocessed UC tissue fragments directly at reception of the donated tissues using 10% Me2SO-based cryosolution and a commercial clinical-grade defined cryopreservation medium (Cryostor®), showing the preservation of all Critical Quality Attributes in terms of identity, potency and kinetic parameters. In summary, our study provides evidence that cryopreservation of large unprocessed UC tissue fragments (5-13.5 cm) supports subsequent progenitor cell isolation and derivation of MSC,WJ, preserving their viability, identity, proliferation rates and potency.

Clinical effects of intrathecal administration of expanded Wharton jelly mesenchymal stromal cells in patients with chronic complete spinal cord injury: a randomized controlled study.

BACKGROUND AIMS: Spinal cord injury (SCI) represents a devastating condition leading to severe disability related to motor, sensory and autonomic dysfunction. Stem cell transplantation is considered a potential emerging therapy to stimulate neuroplastic and neuroregenerative processes after SCI. In this clinical trial, the authors investigated the safety and clinical recovery effects of intrathecal infusion of expanded Wharton jelly mesenchymal stromal cells (WJ-MSCs) in chronic complete SCI patients. METHODS: The authors designed a randomized, double-blind, crossover, placebo-controlled, phase 1/2a clinical trial (NCT03003364). Participants were 10 patients (7 males, 3 females, age range, 25-47 years) with chronic complete SCI (American Spinal Injury Association A) at dorsal level (T3-11). Patients were randomly assigned to receive a single dose of intrathecal ex vivo-expanded WJ-MSCs (10 × 106 cells) from human umbilical cord or placebo and were then switched to the other arm at 6 months. Clinical evaluation (American Spinal Injury Association impairment scale motor and sensory score, spasticity, neuropathic pain, electrical perception and pain thresholds), lower limb motor evoked potentials (MEPs) and sensory evoked potentials (SEPs), Spinal Cord Independence Measure and World Health Organization Quality of Life Brief Version were assessed at baseline, 1 month, 3 months and 6 months after each intervention. Urodynamic studies and urinary-specific quality of life (Qualiveen questionnaire) as well as anorectal manometry, functional assessment of bowel dysfunction (Rome III diagnostic questionnaire) and severity of fecal incontinence (Wexner score) were conducted at baseline and at 6 months after each intervention. RESULTS: Intrathecal transplantation of WJ-MSCs was considered safe, with no significant side effects. Following MSC infusion, the authors found significant improvement in pinprick sensation in the dermatomes below the level of injury compared with placebo. Other clinically relevant effects, such as an increase in bladder maximum capacity and compliance and a decrease in bladder neurogenic hyperactivity and external sphincter dyssynergy, were observed only at the individual level. No changes in motor function, spasticity, MEPs, SEPs, bowel function, quality of life or independence measures were observed. CONCLUSIONS: Intrathecal transplantation of human umbilical cord-derived WJ-MSCs is a safe intervention. A single intrathecal infusion of WJ-MSCs in patients with chronic complete SCI induced sensory improvement in the segments adjacent to the injury site.

Evaluation of a cell-based osteogenic formulation compliant with good manufacturing practice for use in tissue engineering.

Proper bony tissue regeneration requires mechanical stabilization, an osteogenic biological activity and appropriate scaffolds. The latter two elements can be combined in a hydrogel format for effective delivery, so it can readily adapt to the architecture of the defect. We evaluated a Good Manufacturing Practice-compliant formulation composed of bone marrow-derived mesenchymal stromal cells in combination with bone particles (Ø = 0.25 to 1 µm) and fibrin, which can be readily translated into the clinical setting for the treatment of bone defects, as an alternative to bone tissue autografts. Remarkably, cells survived with unaltered phenotype (CD73+, CD90+, CD105+, CD31-, CD45-) and retained their osteogenic capacity up to 48 h after being combined with hydrogel and bone particles, thus demonstrating the stability of their identity and potency. Moreover, in a subchronic toxicity in vivo study, no toxicity was observed upon subcutaneous administration in athymic mice and signs of osteogenesis and vascularization were detected 2 months after administration. The preclinical data gathered in the present work, in compliance with current quality and regulatory requirements, demonstrated the feasibility of formulating an osteogenic cell-based tissue engineering product with a defined profile including identity, purity and potency (in vitro and in vivo), and the stability of these attributes, which complements the preclinical package required prior to move towards its use of prior to its clinical use.

Levels of IL-17F and IL-33 correlate with HLA-DR activation in clinical-grade human bone marrow-derived multipotent mesenchymal stromal cell expansion cultures.

BACKGROUND AIMS: Multipotent mesenchymal stromal cell (MSC)-based medicines are extensively investigated for use in regenerative medicine and immunotherapy applications. The International Society for Cell and Gene Therapy (ISCT) proposed a panel of cell surface molecules for MSC identification that includes human leukocyte antigen (HLA)-DR as a negative marker. However, its expression is largely unpredictable despite production under tightly controlled conditions and compliance with current Good Manufacturing Practices. Herein, we report the frequency of HLA-DR expression in 81 batches of clinical grade bone marrow (BM)-derived MSCs and investigated its impact on cell attributes and culture environment. METHODS: The levels of 15 cytokines (interleukin [IL]-1ß, IL-4, IL-6, IL-10, IL-17A, IL-17F, IL-21, IL-22, IL-23, IL-25, IL-31, IL-33, interferon-γ, soluble CD40 ligand and tumor necrosis factor-α) were determined in sera supplements and supernatants of BM-MSC cultures. Identity, multipotentiality and immunopotency assays were performed on high (>20% of cells) and low (≤20% of cells) HLA-DR+ cultures. RESULTS: A correlation was found between HLA-DR expression and levels of IL-17F and IL-33. Expression of HLA-DR did neither affect MSC identity, in vitro tri-lineage differentiation potential (into osteogenic, chondrogenic and adipogenic lineages), nor their ability to inhibit the proliferation of stimulated lymphocytes. DISCUSSION: Out of 81 batches of BM-MSCs for autologous use analyzed, only three batches would have passed the ISCT criteria (<2%), whereas 60.5% of batches were compliant with low HLA-DR values (≤20%). Although a cause-effect relationship cannot be drawn, we have provided a better understanding of signaling events and cellular responses in expansion culture conditions relating with HLA-DR expression.

Stability enhancement of clinical grade multipotent mesenchymal stromal cell-based products.

BACKGROUND: Successful delivery of cell-based therapeutics into patients is compromised by their short shelf-life upon release from production facilities due to the living nature of the active component that rapidly loses viability, and therefore its properties. In this context, the use of appropriate additives may contribute to the stabilisation of the cellular component within specifications for a longer time until administration. RESULTS: In the present study, we evaluated the effect of different formulations on the stability of viability, identity, and potency of clinical grade multipotent mesenchymal stromal cells in suspension, both electrolyte solution and protein content were found to impact on their shelf-life. Particularly cryopreservation of cells in a Plasmalyte 148 supplemented with 2% (w/v) AlbIX (a yeast-derived recombinant albumin) and 10% (v/v) dimethyl sulfoxide, and final formulation post-thawing in Plasmalyte 148 supplemented with 2% (w/v) AlbIX enabling prolonged stability from 24 h up to 72 h in optimal conditions. Further investigation on the mechanisms of action involved revealed a delay of apoptosis progression into late stage when AlbIX was present. CONCLUSIONS: The use of optimal formulations for each cell type of interest is crucial to extend the shelf life of cell-based pharmaceuticals and contribute to solve logistical challenges. We demonstrated that the use of Plasmalyte 148 supplemented with 2% (w/v) AlbIX resulted in superior stability of multipotent mesenchymal stromal cells without affecting their identity and multipotency.

Assessment of biodistribution using mesenchymal stromal cells: Algorithm for study design and challenges in detection methodologies.

BACKGROUND AIMS: Biodistribution of candidate cell-based therapeutics is a critical safety concern that must be addressed in the preclinical development program. We aimed to design a decision tree based on a series of studies included in actual dossiers approved by competent regulatory authorities, noting that the design, execution and interpretation of pharmacokinetics studies using this type of therapy is not straightforward and presents a challenge for both developers and regulators. METHODS: Eight studies were evaluated for the definition of a decision tree, in which mesenchymal stromal cells (MSCs) were administered to mouse, rat and sheep models using diverse routes (local or systemic), cell labeling (chemical or genetic) and detection methodologies (polymerase chain reaction [PCR], immunohistochemistry [IHC], fluorescence bioimaging, and magnetic resonance imaging [MRI]). Moreover, labeling and detection methodologies were compared in terms of cost, throughput, speed, sensitivity and specificity. RESULTS: A decision tree was defined based on the model chosen: (i) small immunodeficient animals receiving heterologous MSC products for assessing biodistribution and other safety aspects and (ii) large animals receiving homologous labeled products; this contributed to gathering data not only on biodistribution but also on pharmacodynamics. PCR emerged as the most convenient technique despite the loss of spatial information on cell distribution that can be further assessed by IHC. DISCUSSION: This work contributes to the standardization in the design of biodistribution studies by improving methods for accurate assessment of safety. The evaluation of different animal models and screening of target organs through a combination of techniques is a cost-effective and timely strategy.

Design and validation of a consistent and reproducible manufacture process for the production of clinical-grade bone marrow-derived multipotent mesenchymal stromal cells.

BACKGROUND: Multipotent mesenchymal stromal cells (MSC) have achieved a notable prominence in the field of regenerative medicine, despite the lack of common standards in the production processes and suitable quality controls compatible with Good Manufacturing Practice (GMP). Herein we describe the design of a bioprocess for bone marrow (BM)-derived MSC isolation and expansion, its validation and production of 48 consecutive batches for clinical use. METHODS: BM samples were collected from the iliac crest of patients for autologous therapy. Manufacturing procedures included: (i) isolation of nucleated cells (NC) by automated density-gradient centrifugation and plating; (ii) trypsinization and expansion of secondary cultures; and (iii) harvest and formulation of a suspension containing 40 ± 10 × 10(6) viable cells. Quality controls were defined as: (i) cell count and viability assessment; (ii) immunophenotype; and (iii) sterility tests, Mycoplasma detection, endotoxin test and Gram staining. RESULTS: A 3-week manufacturing bioprocess was first designed and then validated in 3 consecutive mock productions, prior to producing 48 batches of BM-MSC for clinical use. Validation included the assessment of MSC identity and genetic stability. Regarding production, 139.0 ± 17.8 mL of BM containing 2.53 ± 0.92 × 10(9) viable NC were used as starting material, yielding 38.8 ± 5.3 × 10(6) viable cells in the final product. Surface antigen expression was consistent with the expected phenotype for MSC, displaying high levels of CD73, CD90 and CD105, lack of expression of CD31 and CD45 and low levels of HLA-DR. Tests for sterility, Mycoplasma, Gram staining and endotoxin had negative results in all cases. DISCUSSION: Herein we demonstrated the establishment of a feasible, consistent and reproducible bioprocess for the production of safe BM-derived MSC for clinical use.

Evaluation of a cell-banking strategy for the production of clinical grade mesenchymal stromal cells from Wharton's jelly.

BACKGROUND AIMS: Umbilical cord (UC) has been proposed as a source of mesenchymal stromal cells (MSCs) for use in experimental cell-based therapies provided that its collection does not raise any risk to the donor, and, similar to bone marrow and lipoaspirates, UC-MSCs are multipotent cells with immuno-modulative properties. However, some of the challenges that make a broader use of UC-MSCs difficult include the limited availability of fresh starting tissue, time-consuming processing for successful derivation of cell lines, and the lack of information on identity, potency and genetic stability in extensively expanded UC-MSCs, which are necessary for banking relevant cell numbers for preclinical and clinical studies. METHODS: Factors affecting the success of the derivation process (namely, time elapsed from birth to processing and weight of fragments), and methods for establishing a two-tiered system of Master Cell Bank and Working Cell Bank of UC-MSCs were analyzed. RESULTS: Efficient derivation of UC-MSCs was achieved by using UC fragments larger than 7 g that were processed within 80 h from birth. Cells maintained their immunophenotype (being highly positive for CD105, CD90 and CD73 markers), multi-potentiality and immuno-modulative properties beyond 40 cumulative population doublings. No genetic abnormalities were found, as determined by G-banding karyotype, human telomerase reverse transcriptase activity was undetectable and no toxicity was observed in vivo after intravenous administration of UC-MSCs in athymic rats. DISCUSSION: This works demonstrates the feasibility of the derivation and large-scale expansion of UC-MSCs from small and relatively old fragments of UC typically discarded from public cord blood banking programs.

Quality compliance in the shift from cell transplantation to cell therapy in non-pharma environments.

Along with academic and charitable organizations, transfusion centers have ventured into the stem cell field, with the aim of testing of novel cell-based therapeutics in a clinical setting for future marketing approval. The fact that quality management structures, which are required for compliance with good scientific practice regulations, were originally designed for product development in corporate environments represents a major challenge for many developers. In this Commentary, challenges that non-pharmaceutical institutions must overcome to translate cell-based products into clinical therapies will be discussed from a quality standpoint. Furthermore, our development experience for a mesenchymal stromal cell-based therapy will be shared as a case study.

Identification of critical process parameters for expansion of clinical grade human Wharton's jelly-derived mesenchymal stromal cells in stirred-tank bioreactors.

Cell therapies based on multipotent mesenchymal stromal cells (MSCs) are traditionally produced using 2D culture systems and platelet lysate- or serum-containing media (SCM). Although cost-effective for single-dose autologous treatments, this approach is not suitable for larger scale manufacturing (e.g., multiple-dose autologous or allogeneic therapies with banked MSCs); automated, scalable and Good Manufacturing Practices (GMP)-compliant platforms are urgently needed. The feasibility of transitioning was evaluated from an established Wharton's jelly MSCs (WJ-MSCs) 2D production strategy to a new one with stirred-tank bioreactors (STRs). Experimental conditions included four GMP-compliant xeno- and serum-free media (XSFM) screened in 2D conditions and two GMP-grade microcarriers assessed in 0.25 L-STRs using SCM. From the screening, a XSFM was selected and compared against SCM using the best-performing microcarrier. It was observed that SCM outperformed the 2D-selected medium in STRs, reinforcing the importance of 2D-to-3D transition studies before translation into clinical production settings. It was also found that attachment efficiency and microcarrier colonization were essential to attain higher fold expansions, and were therefore defined as critical process parameters. Nevertheless, WJ-MSCs were readily expanded in STRs with both media, preserving critical quality attributes in terms of identity, viability and differentiation potency, and yielding up to 1.47 × 109 cells in a real-scale 2.4-L batch.