Acceleration of Translational Mesenchymal Stromal Cell Therapy Through Consistent Quality GMP Manufacturing

Comprehensive analysis of secretome and transcriptome stability of Wharton jelly mesenchymal stromal cells during good manufacturing practice-compliant production

BACKGROUND

Mesenchymal stromal cells (MSCs) hold promise for cell-based therapies due to their ability to stimulate tissue repair and modulate immune responses. Umbilical cord-derived MSCs from Wharton jelly (WJ) offer advantages such as low immunogenicity and potent immune modulatory effects. However, ensuring consistent quality and safety throughout their manufacturing process remains critical. RNA sequencing (RNA-seq) emerges as a crucial tool for assessing genetic stability and expression dynamics in cell-based therapeutic products.

METHODS

We examined the secretome and transcriptome of WJ-MSC signatures throughout Good Manufacturing Practice (GMP) production, focusing on the performance of total RNA or Massive Analysis of cDNA Ends (MACE) sequencing.

RESULTS

Through extensive transcriptomic analysis, we demonstrated consistent stability of WJ-MSC expression signatures across different manufacturing stages. Notably, MACE-seq showed improved identification of key expression patterns related to senescence and immunomodulation.

CONCLUSIONS

These findings highlight the potential of MACE-seq as a quality assessment tool for WJ-MSC-based therapies, ensuring their efficacy and safety in clinical applications. Importantly, MACE-seq demonstrated its value in characterizing WJ-MSC-derived products, offering insights that traditional assays cannot provide.

Enzyme applications in baking: From dough development to shelf-life extension

Enzymes play a vital role in baking, providing significant benefits from dough development to extending shelf life, which enhances product quality and consistency. Acting as biological catalysts, enzymes such as proteases and amylases break down proteins and starches, modifying dough rheology and improving fermentation. Lipases and oxidases further refine dough texture through emulsification and oxidation, while lipases also produce fatty acid derivatives during fermentation, contributing to the flavor and aroma of baked goods. Xylanases and cellulases optimize dough handling by altering fiber structure, and amylases help maintain moisture and texture, extending the shelf life of baked products. Ensuring regulatory compliance is essential when incorporating enzymes into baking processes, as bakers must address enzyme stability and determine appropriate dosages for reliable outcomes. Ongoing research is exploring innovative enzyme applications, including customized enzyme blends that target specific product qualities, offering new possibilities for product differentiation and innovation. In summary, enzyme-driven advancements present bakers with opportunities to improve product quality, shelf life, and consistency, while meeting industry regulations. This review emphasizes the critical impact enzymes have on dough properties and finished product characteristics, highlighting their role in driving future innovations within the baking industry.

Primary human mesenchymal stem cell culture under xeno-free conditions using surface-modified cellulose nanofiber scaffolds

Stem cell culture often requires various animal-derived components such as serum and collagen. This limits its practical use. Therefore, xeno-free (xenogeneic component-free) culture systems are receiving increased attention. Herein, we propose xeno-free, plant-derived cellulose nanofibers (CNFs) with different surface chemistry: 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized CNFs (TOCNFs) with carboxy groups and surface-sulfated CNFs (S-CNFs) for the proliferation of human mesenchymal stem cells (hMSCs) under various serum conditions. We cultured bone marrow-derived hMSCs on CNF scaffolds with various fiber lengths and functional group contents. Original CNFs were bioinert materials that did not contribute to cell adhesion. In contrast, the surface-modified CNFs facilitated the proliferation of immortalized hMSCs under normal and low-serum conditions. The TOCNFs (COONa: 1.47 mmol g-1; length: 0.53 μm), the S-CNFs (OSO3Na: 0.64 mmol g-1; 0.61 μm), and a combination of the two (1:1 by weight) enabled immortalized hMSCs to maintain their multipotency, even under serum-free conditions. Primary cultured hMSCs proliferated well on the TOCNF/S-CNF scaffolds in a completely serum-free medium, comparable to animal-derived type I collagen, although few hMSCs adhered to the standard polystyrene substrate. Our strategy of using surface-modified CNFs will inform the development of xeno-free culture systems to avoid the use of animal-derived materials for both cell culture media and scaffolds.

Definition of Synovial Mesenchymal Stem Cells for Meniscus Regeneration by the Mechanism of Action and General Amp1200 Gene Expression

The quality control (QC) of pharmaceutical-grade cell-therapy products, such as mesenchymal stem cells (MSCs), is challenging. Attempts to develop such products have been hampered by difficulties defining cell-type-specific characteristics and therapeutic mechanisms of action (MoAs). Although we have developed a cell therapy product, FF-31501, consisting of human synovial MSCs (SyMSCs), it was difficult to find specific markers for SyMSCs and to define the cells separately from other MSCs. The purpose of this study was to create a method for identifying and defining SyMSCs from other tissue-derived MSCs and to delve deeper into the mechanism of action of SyMSC-induced meniscus regeneration. Specifically, as a cell-type-dependent approach, we constructed a set of 1143 genes (Amp1200) reported to be associated with MSCs and established a method to evaluate them by correlating gene expression patterns. As a result, it was possible to define SyMSCs separately from other tissue-derived MSCs and non-MSCs. In addition, the gene expression analysis also highlighted TNSF-15. The in vivo rat model of meniscus injury found TNSF-15 to be an essential molecule for meniscus regeneration via SyMSC administration. This molecule and previously reported MoA molecules allowed an MoA-dependent approach to define the mechanism of action for SyMSCs. Therefore, SyMSCs for meniscus regeneration were defined by means of two approaches: the method to separate them from other MSCs and the identification of the MoA molecules. These approaches would be useful for the QC of cell therapy products.

Emerging Landscape of In Vitro Models for Assessing Rheumatoid Arthritis Management

Rheumatoid arthritis (RA) is a complex condition that is influenced by various causes, including immunological, genetic, and environmental factors. Several studies using animal models have documented immune system dysfunction and described the clinical characteristics of the disease. These studies have provided valuable insights into the pathogenesis of inflammatory arthritis and the identification of new targets for treatment. Nevertheless, none of these animal models successfully replicated all the characteristics of RA. Additionally, numerous experimental medications, which were developed based on our enhanced comprehension of the immune system's function in RA, have shown potential in animal research but ultimately proved ineffective during different stages of clinical trials. There have been several novel therapy alternatives, which do not achieve a consistently outstanding therapeutic outcome in all patients. This underscores the importance of employing the progress in in vitro models, particularly 3D models like tissue explants, and diverse multicomponent approaches such as coculture strategies, synovial membrane, articular cartilage, and subchondral bone models that accurately replicate the structural characteristics of RA pathophysiology. These methods are crucial for the advancement of potential therapeutic strategies. This review discusses the latest advancements in in vitro models and their potential to greatly impact research on managing RA.

Upstream Process Protocol for MSCs Isolated from Different Human-Based Tissue Origins

This chapter introduces the increasing significance of mesenchymal stromal/stem cell (MSC) production in regenerative medicine and cellular therapeutics, outlines the growing interest in MSCs for various medical applications, and highlights their potential in advanced therapy medicinal products (ATMPs) and the advancements in cell culture technologies that have facilitated large-scale MSC production under Good Manufacturing Practices (GMP), ensuring safety and efficacy. This chapter describes an optimized upstream protocol for laboratory-scale MSC production from different tissue sources. This protocol, conducted in flasks, controls critical parameters and lays the foundation for downstream processing to generate ATMPs. This comprehensive approach underscores the potential of MSCs in clinical applications and the importance of tailored production processes.

A GMP-compliant manufacturing method for Wharton's jelly-derived mesenchymal stromal cells

BACKGROUND

Wharton's jelly-derived mesenchymal stem cells (WJ-MSCs) hold great therapeutic potential in regenerative medicine. Therefore, it is crucial to establish a Good Manufacturing Practice (GMP)-compliant methodology for the isolation and culture of WJ-MSCs. Through comprehensive research, encompassing laboratory-scale experiments to pilot-scale studies, we aimed to develop standardized protocols ensuring the high yield and quality of WJ-MSCs manufacturing.

METHODS

Firstly, optimization of parameters for the enzymatic digestion method used to isolate WJ-MSCs was conducted. These parameters included enzyme concentrations, digestion times, seeding densities, and culture media. Additionally, a comparative analysis between the explant method and the enzymatic digestion method was performed. Subsequently, the consecutive passaging of WJ-MSCs, specifically up to passage 9, was evaluated using the optimized method. Finally, manufacturing processes were developed and scaled up, starting from laboratory-scale flask-based production and progressing to pilot-scale cell factory-based production. Furthermore, a stability study was carried out to assess the storage and use of drug products (DPs).

RESULTS

The optimal parameters for the enzymatic digestion method were a concentration of 0.4 PZ U/mL Collagenase NB6 and a digestion time of 3 h, resulting in a higher yield of P0 WJ-MSCs. In addition, a positive correlation between the weight of umbilical cord tissue and the quantities of P0 WJ-MSCs has been observed. Evaluation of different concentrations of human platelet lysate revealed that 2% and 5% concentrations resulted in similar levels of cell expansion. Comparative analysis revealed that the enzymatic digestion method exhibited faster outgrowth of WJ-MSCs compared to the explant method during the initial passage. Passages 2 to 5 exhibited higher viability and proliferation ability throughout consecutive passaging. Moreover, scalable manufacturing processes from the laboratory scale to the pilot scale were successfully developed, ensuring the production of high-quality WJ-MSCs. Multiple freeze-thaw cycles of the DPs led to reduced cell viability and viable cell concentration. Subsequent thawing and dilution of the DPs resulted in a significant decrease in both metrics, especially when stored at 20-27 °C.

CONCLUSION

This study offers valuable insights into optimizing the isolation and culture of WJ-MSCs. Our scalable manufacturing processes facilitate the large-scale production of high-quality WJ-MSCs. These findings contribute to the advancement of WJ-MSCs-based therapies in regenerative medicine.

Turning Trash Into Treasure: A Simple Protocol for Human Mesenchymal Stromal Cell Isolation From Used Bone Marrow Collection Kits

The therapeutic potential of mesenchymal stromal cells (MSCs) has been extensively investigated in both preclinical and clinical settings. Recent years have witnessed the emergence of numerous isolation protocols and culture techniques, ranging from the selection of subpopulations to preserve stemness to preconditioning strategies aimed at enhancing therapeutic efficacy, tailored to the specific tissue source. In this protocol, we present a straightforward and cost-effective method for isolating human MSCs (hMSCs) from discarded bone marrow collection kits (comprising bag and filter systems) originally intended for removing impurities and unwanted cellular debris from the collected bone marrow aspirate, ensuring the purity of the stem cell population during stem cell transplantation. Utilizing basic laboratory equipment, we demonstrate the isolation of hMSCs, highlighting the expression of specific surface antigens, and multilineage differentiation into adipogenic, osteogenic, and chondrogenic lineages in vitro. This sustainable and resource-efficient approach not only contributes to reducing medical waste but also holds promise for advancing regenerative medicine applications. © 2024 Wiley Periodicals LLC. Basic Protocol 1: Isolation of human mesenchymal stromal cells from bone marrow collection kits Basic Protocol 2: Culture of human mesenchymal stromal cells Basic Protocol 3: Characterization of human mesenchymal stromal cells with flow cytometry analysis Basic Protocol 4: Characterization of human mesenchymal stromal cells with multilineage differentiation under in vitro conditions.

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.

Pan PPAR agonist stimulation of induced MSCs produces extracellular vesicles with enhanced renoprotective effect for acute kidney injury

BACKGROUND

Acute kidney injury (AKI) has a complex pathophysiology and imposes serious health concerns worldwide. Extracellular vesicles (EVs) derived from induced mesenchymal stem cells (iMSCs) have been recognized as novel cell-free therapeutics for various inflammatory and degenerative disorders. In this study, we investigated whether iMSCs stimulated with a pan-peroxisome proliferator-activated receptor (PPAR) agonist could enhance the therapeutic efficacy of EVs against AKI.

METHODS

Human iMSCs were primed with or without lanifibranor, a PPAR agonist for 24 h, and EVs were collected after an additional 24 h. The basic characteristics of EVs were evaluated using cryo-transmission electron microscopy imaging, immunoblot detection of EV markers, nanoparticle tracking analysis, and localization in AKI kidneys. In vitro, the potential of the EVs to promote the growth and survival of HK-2 cells undergoing cisplatin-induced apoptosis and anti-inflammatory effects in M1-polarized THP-1 was compared. Subsequently, AKI was induced in BALB/c mice using cisplatin. After 8 and 24 h of cisplatin treatment, iMSC-EVs or pan-PPAR-iMSC-EVs were injected intravascularly. At 96 h after cisplatin administration, the renoprotective effects of iMSC-EVs or pan-PPAR-iMSC-EVs in inhibiting inflammation and apoptosis were compared using serum biochemistry, histology, immunohistochemistry, and gene expression analysis by qPCR.

RESULTS

Both EV types expressed EV markers and had typical EV morphology, and their localization in the renal tissue was confirmed. The proliferation and survival of HK-2 cells were higher in pan-PPAR-iMSC-EVs than those in iMSC-EVs. In M1-polarized THP-1 cells, the reduction in the mRNA expression of inflammatory cytokines was more significant in pan-PPAR-iMSC-EVs than that in iMSC-EVs. In the mouse model of cisplatin-induced AKI, pan-PPAR-iMSC-EVs markedly enhanced renoprotective effects compared to iMSC-EVs. Specifically, pan-PPAR-iMSC-EVs reduced tissue inflammation, immune cell infiltration, and apoptosis. Pan-PPAR-iMSC-EVs also increased renal capillary density.

CONCLUSION

Priming iMSCs with a PPAR agonist significantly improved the therapeutic potential of EVs by reducing inflammation and apoptosis. The reported strategy may contribute to the development of a novel cell-free option for AKI treatment.

TRIAL REGISTRATION

Not applicable.

Current trends and promising clinical utility of IPSC-derived MSC (iMSC)

Mesenchymal stem cells (MSCs) differentiated from human induced pluripotent stem cells (iPSC) or induced MSC (iMSCs) are expected to address issues of scalability and safety as well as the difficulty in producing homogenous clinical grade MSCs as demonstrated by the promising outcomes from preclinical and clinical trials, currently ongoing. The assessment of iMSCs based in vitro and in vivo studies have thus far showed more superior performance as compared to that of the primary or native human MSCs, in terms of cell proliferation, expansion capacity, immunomodulation properties as well as the influence of paracrine signaling and exosomal influence in cell-cell interaction. In this chapter, an overview of current well-established methods in generating a sustainable source of iMSCs involving well defined culture media is discussed followed by the properties of iMSC as compared to that of MSC and its promising prospects for continuous development into potential clinical grade applications.

Adipose tissue-derived human mesenchymal stromal cells can better suppress complement lysis, engraft and inhibit acute graft-versus-host disease in mice

BACKGROUND

Acute graft-versus-host disease (aGvHD) is a life-threatening complication of allogeneic hematopoietic stem cell transplantation (HSCT). Transplantation of immunosuppressive human mesenchymal stromal cells (hMSCs) can protect against aGvHD post-HSCT; however, their efficacy is limited by poor engraftment and survival. Moreover, infused MSCs can be damaged by activated complement, yet strategies to minimise complement injury of hMSCs and improve their survival are limited.

METHODS

Human MSCs were derived from bone marrow (BM), adipose tissue (AT) and umbilical cord (UC). In vitro immunomodulatory potential was determined by co-culture experiments between hMSCs and immune cells implicated in aGvHD disease progression. BM-, AT- and UC-hMSCs were tested for their abilities to protect aGvHD in a mouse model of this disease. Survival and clinical symptoms were monitored, and target tissues of aGvHD were examined by histopathology and qPCR. Transplanted cell survival was evaluated by cell tracing and by qPCR. The transcriptome of BM-, AT- and UC-hMSCs was profiled by RNA-sequencing. Focused experiments were performed to compare the expression of complement inhibitors and the abilities of hMSCs to resist complement lysis.

RESULTS

Human MSCs derived from three tissues divergently protected against aGvHD in vivo. AT-hMSCs preferentially suppressed complement in vitro and in vivo, resisted complement lysis and survived better after transplantation when compared to BM- and UC-hMSCs. AT-hMSCs also prolonged survival and improved the symptoms and pathological features of aGvHD. We found that complement-decay accelerating factor (CD55), an inhibitor of complement, is elevated in AT-hMSCs and contributed to reduced complement activation. We further report that atorvastatin and erlotinib could upregulate CD55 and suppress complement in all three types of hMSCs.

CONCLUSION

CD55, by suppressing complement, contributes to the improved protection of AT-hMSCs against aGvHD. The use of AT-hMSCs or the upregulation of CD55 by small molecules thus represents promising new strategies to promote hMSC survival to improve the efficacy of transplantation therapy. As complement injury is a barrier to all types of hMSC therapy, our findings are of broad significance to enhance the use of hMSCs for the treatment of a wide range of disorders.

Potency assays and biomarkers for cell-based advanced therapy medicinal products

Advanced Therapy Medicinal Products (ATMPs) based on somatic cells expanded in vitro, with or without genetic modification, is a rapidly growing area of drug development, even more so following the marketing approval of several such products. ATMPs are produced according to Good Manufacturing Practice (GMP) in authorized laboratories. Potency assays are a fundamental aspect of the quality control of the end cell products and ideally could become useful biomarkers of efficacy in vivo. Here we summarize the state of the art with regard to potency assays used for the assessment of the quality of the major ATMPs used clinic settings. We also review the data available on biomarkers that may substitute more complex functional potency tests and predict the efficacy in vivo of these cell-based drugs.

A scalable culture system incorporating microcarrier for specialised mesenchymal stem cells from human embryonic stem cells

Mesenchymal stromal cells (MSCs) derived from human embryonic stem cells (hESCs) are a desirable cell source for cell therapy owing to their capacity to be produced stably and homogeneously in large quantities. However, a scalable culture system for hPSC-derived MSCs is urgently needed to meet the cell quantity and quality requirements of practical clinical applications. In this study, we developed a new microcarrier with hyaluronic acid (HA) as the core material, which allowed scalable serum-free suspension culture of hESC-derived MSCs (IMRCs). We used optimal microcarriers with a coating collagen concentration of 100 ​μg/mL or concave-structured surface (cHAMCs) for IMRC amplification in a stirred bioreactor, expanding IMRCs within six days with the highest yield of over one million cells per milliliter. In addition, the harvested cells exhibited high viability, immunomodulatory and regenerative therapeutic promise comparable to monolayer cultured MSCs while showing more increased secretion of extracellular matrix (ECM), particularly collagen-related proteins. In summary, we have established a scalable culture system for hESC-MSCs, providing novel approaches for future cell therapies.

The Art of Stem Cell-Based Therapy

Potency assays represent crucial experiments at the hub of the comprehensive complexity surrounding cell therapy. Moreover, numerous factors beyond biological and scientific considerations are involved in achieving successful potency assays that fulfil regulatory authority approval for a new advanced therapy medicinal product. Though this can mean a frustratingly long period of discovery and development, progress in cell therapy is nowadays proceeding remarkably quickly, assisted by the potency assay rigorously placing emphasis on the need to critically analyse the key factor/s responsible for the therapeutic mechanism of action. History has shown that it can take many decades for there to be an improved understanding of a mechanism of action. Yet the chasing of precise targets has revolutionised medicine, with no clearer example than approaches to viral pandemics. The centuries involved in the eradication of smallpox have paved the way for an unprecedented pace of vaccine development for the Covid-19 pandemic. Such extraordinary accomplishments foster encouragement that similarly for stem cell-based therapy, our scientific knowledge will continue to improve apace. This chapter focuses on the art of experimentation and discovery, introducing potency assay requisites and numerous factors that can influence potency assay outcomes. A comprehensive understanding of potency assays and their development can hasten the provision of new cell therapies to help resolve burdensome diseases of unmet medical need.

Interferon-Gamma Primed Human Clonal Mesenchymal Stromal Cell Sheets Exhibit Enhanced Immunosuppressive Function

Mesenchymal stromal cells (MSCs) represent a promising treatment for immune-related diseases due to their diverse immunomodulatory paracrine functions. However, progress of culture-expanded MSCs is hindered by inconsistent cell function, poor localization, and insufficient retention when administered as suspended cell injections, thus placing spatiotemporal dosing constraints on therapeutic functions. To address these limitations, we introduce the combination of in vitro interferon-gamma (IFN-γ) priming, a key stimulator of MSC immunosuppressive potency, and thermoresponsive cultureware to harvest cultured MSCs as directly transplantable scaffold-free immunosuppressive cell sheets. Here, we demonstrate that MSC sheets produced with IFN-γ priming upregulate expression of immunosuppressive factors indoleamine 2,3-dioxygenase (IDO-1), interleukin-10 (IL-10), programmed death ligand-1 (PD-L1), and prostaglandin E2 (PGE2) in both dose- and duration-dependent manners. In addition, IFN-γ primed MSC sheets showed increased ability to inhibit T-cell proliferation via indirect and direct contact, specifically related to increased IDO-1 and PGE2 concentrations. Furthermore, this study's use of human clinical-grade single-cell-derived clonal bone marrow-derived MSCs, contributes to the future translatability and clinical relevancy of the produced sheets. Ultimately, these results present the combination of IFN-γ priming and MSC sheets as a new strategy to improve MSC-mediated treatment of localized inflammatory diseases.

Characterizing the secretome of licensed hiPSC-derived MSCs

Although mesenchymal stromal cells (MSCs) from primary tissues have been successfully applied in the clinic, their expansion capabilities are limited and results are variable. MSCs derived from human-induced pluripotent stem cells (hiMSCs) are expected to overcome these limitations and serve as a reproducible and sustainable cell source. We have explored characteristics and therapeutic potential of hiMSCs in comparison to hBMSCs. RNA sequencing confirmed high resemblance, with average Pearson correlation of 0.88 and Jaccard similarity index of 0.99, and similar to hBMSCs the hiMSCs released extracellular vesicles with in vitro immunomodulatory properties. Potency assay with TNFα and IFNγ demonstrated an increase in well-known immunomodulatory genes such as IDO1, CXCL8/IL8, and HLA-DRA which was also highlighted by enhanced secretion in the media. Notably, expression of 125 genes increased more than 1000-fold. These genes were predicted to be regulated by NFΚB signaling, known to play a central role in immune response. Altogether, our data qualify hiMSCs as a promising source for cell therapy and/or cell-based therapeutic products. Additionally, the herewith generated database will add to our understanding of the mode of action of regenerative cell-based therapies and could be used to identify relevant potency markers.

Optimization of Mesenchymal Stromal Cell (MSC) Manufacturing Processes for a Better Therapeutic Outcome

MSCs products as well as their derived extracellular vesicles, are currently being explored as advanced biologics in cell-based therapies with high expectations for their clinical use in the next few years. In recent years, various strategies designed for improving the therapeutic potential of mesenchymal stromal cells (MSCs), including pre-conditioning for enhanced cytokine production, improved cell homing and strengthening of immunomodulatory properties, have been developed but the manufacture and handling of these cells for their use as advanced therapy medicinal products (ATMPs) remains insufficiently studied, and available data are mainly related to non-industrial processes. In the present article, we will review this topic, analyzing current information on the specific regulations, the selection of living donors as well as MSCs from different sources (bone marrow, adipose tissue, umbilical cord, etc.), in-process quality controls for ensuring cell efficiency and safety during all stages of the manual and automatic (bioreactors) manufacturing process, including cryopreservation, the use of cell banks, handling medicines, transport systems of ATMPs, among other related aspects, according to European and US legislation. Our aim is to provide a guide for a better, homogeneous manufacturing of therapeutic cellular products with special reference to MSCs.

New paradigms in regenerative engineering: Emerging role of extracellular vesicles paired with instructive biomaterials

Mesenchymal stem cells (MSCs) have long been regarded as critical components of regenerative medicine strategies, given their multipotency and persistence in a variety of tissues. Recently, the specific role of MSCs in mediating regenerative outcomes has been attributed (in part) to secreted factors from transplanted cells, namely extracellular vesicles. This viewpoint manuscript highlights the promise of cell-derived extracellular vesicles as agents of regeneration, enhanced by synergy with appropriate biomaterials platforms. Extracellular vesicles are a potentially interesting regenerative tool to enhance the synergy between MSCs and biomaterials. As a result, we believe these technologies will improve patient outcomes through efficient therapeutic strategies resulting in predictable patient outcomes.

Towards regulatory cellular therapies in solid organ transplantation

Organ transplantation is a modern medical success story. However, since its inception it has been limited by the need for pharmacological immunosuppression. Regulatory cellular therapies offer an attractive solution to these challenges by controlling transplant alloresponses through multiple parallel suppressive mechanisms. A number of cell types have seen an accelerated development into human trials and are now on the threshold of a long-awaited breakthrough in personalized transplant therapeutics. Here we assess recent developments with a focus on the most likely candidates, some of which have already facilitated successful immunosuppression withdrawal in early clinical trials. We propose that this may constitute a promising approach in clinical transplantation but also evaluate outstanding issues in the field, providing cause for cautious optimism.

CM from intact hAM: an easily obtained product with relevant implications for translation in regenerative medicine

Background

It is now well established that factors (free or in extracellular vesicles) secreted by mesenchymal stromal cells (MSC) are important mediators of MSC regenerative actions. Herein we produced the secretome (conditioned medium, CM) from MSC isolated from the amniotic membrane (hAMSC) and CM from the intact amniotic membrane (hAM, no manipulation or enzymatic digestion) in order to potentially identify an effective, easy and less expensive secretome to produce for potential applications in regenerative medicine. Given that immunomodulation is a key mechanism of action through which hAMSC contributes to tissue regeneration, we used a comprehensive panel of in vitro immunomodulatory tests to compare the CMs.

Methods

Amniotic membranes were either cut into fragments or used for hAMSC isolation. CMs from hAMSC at passages 0 and 2 were collected after a standard 5-day culture while CM from hAM was collected after a 2- and 5-day culture. Immunomodulation was assessed in terms of PBMC and T-cell proliferation, T-cell subset polarization, T-regulatory cell induction, cell cytotoxicity and monocyte differentiation toward antigen-presenting cells. Furthermore, we performed a comparison between CM obtained from single donors and pooled CM. We also assessed the impact of lyophilization on the immunomodulatory properties of CM.

Results

We demonstrate that CM from hAM has comparable immunomodulatory properties to CM from hAMSC at passages 0 and 2. Furthermore, we demonstrate that pooled CMs have similar effects when compared to CM from single donors used separately. Finally, we demonstrate that lyophilization does not alter the in vitro immunomodulatory properties of CM from hAM and hAMSC.

Conclusions

The results presented herein support the possibility to produce secretome from intact hAM and open the prospect to highly improve the scalability of the GMP production process while reducing the costs and time related to the process of cell isolation and expansion. Moreover, the possibility of having a lyophilized secretome that maintains its original properties would allow for a ready-to-use product with easier handling, shipping and storage. The use of a lyophilized product will also facilitate clinicians by permitting customized reconstitution volumes and methods according to the most suitable formula required by the clinical application.

When Origin Matters: Properties of Mesenchymal Stromal Cells From Different Sources for Clinical Translation in Kidney Disease

Advanced therapy medicinal products (ATMPs) offer new prospects to improve the treatment of conditions with unmet medical needs. Kidney diseases are a current major health concern with an increasing global prevalence. Chronic renal failure appears after many years of impairment, which opens a temporary window to apply novel therapeutic approaches to delay or halt disease progression. The immunomodulatory, anti-inflammatory, and pro-regenerative properties of mesenchymal stromal cells (MSCs) have sparked interest for their use in cell-based regenerative therapies. Currently, several early-phase clinical trials have been completed and many are ongoing to explore MSC safety and efficacy in a wide range of nephropathies. However, one of the current roadblocks to the clinical translation of MSC therapies relates to the lack of standardization and harmonization of MSC manufacturing protocols, which currently hinders inter-study comparability. Studies have shown that cell culture processing variables can have significant effects on MSC phenotype and functionality, and these are highly variable across laboratories. In addition, heterogeneity within MSC populations is another obstacle. Furthermore, MSCs may be isolated from several sources which adds another variable to the comparative assessment of outcomes. There is now a growing body of literature highlighting unique and distinctive properties of MSCs according to the tissue origin, and that characteristics such as donor, age, sex and underlying medical conditions may alter the therapeutic effect of MSCs. These variables must be taken into consideration when developing a cell therapy product. Having an optimal scale-up strategy for MSC manufacturing is critical for ensuring product quality while minimizing costs and time of production, as well as avoiding potential risks. Ideally, optimal scale-up strategies must be carefully considered and identified during the early stages of development, as making changes later in the bioprocess workflow will require re-optimization and validation, which may have a significant long-term impact on the cost of the therapy. This article provides a summary of important cell culture processing variables to consider in the scale-up of MSC manufacturing as well as giving a comprehensive review of tissue of origin-specific biological characteristics of MSCs and their use in current clinical trials in a range of renal pathologies.

Pharmacological Inhibition of p38 MAPK Rejuvenates Bone Marrow Derived-Mesenchymal Stromal Cells and Boosts their Hematopoietic Stem Cell-Supportive Ability

The therapeutic value of mesenchymal stromal cells (MSCs) for various regenerative medicine applications, including hematopoietic stem cell transplantations (HSCT), has been well-established. Owing to their small numbers in vivo, it becomes necessary to expand them in vitro, which leads to a gradual loss of their regenerative capacity. Stress-induced mitogen-activated protein kinase p38 (p38 MAPK) signaling has been shown to compromise the MSC functions. Therefore, we investigated whether pharmacological inhibition of p38 MAPK signaling rejuvenates the cultured MSCs and boosts their functionality. Indeed, we found that the ex vivo expanded MSCs show activated p38 MAPK signaling and exhibit increased oxidative stress. These MSCs show a decreased ability to secrete salutary niche factors, thereby compromising their ability to support hematopoietic stem cell (HSC) self-renewal, proliferation, and differentiation. We, therefore, attempted to rejuvenate the cultured MSCs by pharmacological inhibition of p38 MAPK - a strategy broadly known as "priming of MSCs". We demonstrate that priming of MSCs with a p-38 MAPK inhibitor, PD169316, boosts their niche-supportive functions via upregulation of various HSC-supportive transcription factors. These primed MSCs expand multipotent HSCs having superior homing and long-term reconstitution ability. These findings shed light on the significance of non-cell-autonomous mechanisms operative in the hematopoietic niche and point towards the possible use of pharmacological compounds for rejuvenation of ex vivo cultured MSCs. Such approaches could improve the outcome of regenerative therapies involving in vitro cultured MSCs.