Safety and preliminary efficacy of allogeneic bone marrow-derived multipotent mesenchymal stromal cells for systemic sclerosis: a single-centre, open-label, dose-escalation, proof-of-concept, phase 1/2 study.

BACKGROUND: Systemic sclerosis remains an orphan life-threatening autoimmune disease. The unique immunomodulatory, proangiogenic, and antifibrotic properties of mesenchymal stromal cells provide a strong rationale for mesenchymal stromal cell-based therapy for systemic sclerosis, and treatment with mesenchymal stromal cells has shown benefits in preclinical models of this disease. The safety of allogeneic bone marrow-derived mesenchymal stromal cell administration in patients with severe systemic sclerosis has not yet been established. We aimed to test the safety and feasibility of a single intravenous injection of intrafamilial allogeneic bone marrow-derived mesenchymal stromal cells to treat severe diffuse systemic sclerosis. METHODS: We did an open-label, dose-escalation, proof-of-concept, phase 1/2 study at Saint-Louis-Hospital, Paris, France. Eligible patients were aged 18-70 years with severe diffuse systemic sclerosis, who fulfilled the 2013 American College of Rheumatology and European League Against Rheumatism systemic sclerosis criteria, had a minimum modified Rodnan skin score of 15 (range 0-51), had severe lung, heart, or kidney involvement, and had inadequate response or contraindications to conventional immunosuppressive therapy or autologous haematopoietic stem cell transplantation. Patients with severe comorbidities were excluded. The first ten recipients were to receive a single intravenous infusion of 1 × 106 bone marrow-derived mesenchymal stromal cells per kg bodyweight, and the subsequent ten recipients were to be infused with a single dose of 3 × 106 bone marrow-derived mesenchymal stromal cells per kg bodyweight. The primary endpoint was immediate tolerance during infusion and within the first 10 days after infusion, measured as the occurrence of serious adverse events (grade 3 or higher) in all infused patients. Safety was assessed in all participants during the 24-month follow-up period. This study is registered with ClinicalTrials.gov, NCT02213705. FINDINGS: Between March 24, 2014, and Jan 6, 2020, 20 cisgender individuals (13 women and seven men) with severe diffuse systemic sclerosis were enrolled. All 20 patients were included in the primary outcome analysis. No infusion-related severe adverse events and three infusion-related adverse events occurred in the first 10 days after treatment; one patient had grade 1 flushing and another patient had grade 1 nausea and grade 2 asthenia. After ten days and up to a median follow-up of 24·1 months (IQR 20·8-24·5), 36 non-treatment-related severe adverse events in 14 (70%) patients and no treatment-related adverse event were reported. INTERPRETATION: A single infusion of allogeneic bone marrow-derived mesenchymal stromal cells was safe in patients with severe diffuse systemic sclerosis. Future placebo-controlled trials will help to definitively ascertain the efficacy of mesenchymal stromal cell-based cell therapy from various tissue sources in larger number of patients with systemic sclerosis. FUNDING: French Ministry of Health, Capucine Association, Fonds de Dotation de l'AFER pour la Recherche Médicale, and Agence Nationale de la Recherche (Infrastructure Program Ecell), France.

In vitro bone metastasis dwelling in a 3D bioengineered niche.

Bone is the most frequent metastasis site for breast cancer. As well as dramatically increasing disease burden, bone metastases are also an indicator of poor prognosis. One of the main challenges in investigating bone metastasis in breast cancer is engineering in vitro models that replicate the features of in vivo bone environments. Such in vitro models ideally enable the biology of the metastatic cells to mimic their in vivo behavior as closely as possible. Here, taking benefit of cutting-edge technologies both in microfabrication and cancer cell biology, we have developed an in vitro breast cancer bone-metastasis model. To do so we first 3D printed a bone scaffold that reproduces the trabecular architecture and that can be conditioned with osteoblast-like cells, a collagen matrix, and mineralized calcium. We thus demonstrated that this device offers an adequate soil to seed primary breast cancer bone metastatic cells. In particular, patient-derived xenografts being considered as a better approach than cell lines to achieve clinically relevant results, we demonstrate the ability of this biomimetic bone niche model to host patient-derived xenografted metastatic breast cancer cells. These patient-derived xenograft cells show a long-term survival in the bone model and maintain their cycling propensity, and exhibit the same modulated drug response as in vivo. This experimental system enables access to the idiosyncratic features of the bone microenvironment and cancer bone metastasis, which has implications for drug testing.

Early efficacy evaluation of mesenchymal stromal cells (MSC) combined to biomaterials to treat long bone non-unions.

BACKGROUND AND STUDY AIM: Advanced therapy medicinal products (ATMP) frequently lack of clinical data on efficacy to substantiate a future clinical use. This study aims to evaluate the efficacy to heal long bone delayed unions and non-unions, as secondary objective of the EudraCT 2011-005441-13 clinical trial, through clinical and radiological bone consolidation at 3, 6 and 12 months of follow-up, with subgroup analysis of affected bone, gender, tobacco use, and time since the original fracture. PATIENTS AND METHODS: Twenty-eight patients were recruited and surgically treated with autologous bone marrow derived mesenchymal stromal cells expanded under Good Manufacturing Practices, combined to bioceramics in the surgical room before implantation. Mean age was 39 ± 13 years, 57% were males, and mean Body Mass Index 27 ± 7. Thirteen (46%) were active smokers. There were 11 femoral, 4 humeral, and 13 tibial non-unions. Initial fracture occurred at a mean ± SD of 27.9 ± 31.2 months before recruitment. Efficacy results were expressed by clinical consolidation (no or mild pain if values under 30 in VAS scale), and by radiological consolidation with a REBORNE score over 11/16 points (value of or above 0.6875). Means were statistically compared and mixed models for repeated measurements estimated the mean and confidence intervals (95%) of the REBORNE Bone Healing scale. Clinical and radiological consolidation were analyzed in the subgroups with Spearman correlation tests (adjusted by Bonferroni). RESULTS: Clinical consolidation was earlier confirmed, while radiological consolidation at 3 months was 25.0% (7/28 cases), at 6 months 67.8% (19/28 cases), and at 12 months, 92.8% (26/28 cases including the drop-out extrapolation of two failures). Bone biopsies confirmed bone formation surrounding the bioceramic granules. All locations showed similar consolidation, although this was delayed in tibial non-unions. No significant gender difference was found in 12-month consolidation (95% confidence). Higher consolidation scale values were seen in non-smoking patients at 6 (p = 0.012, t-test) and 12 months (p = 0.011, t-test). Longer time elapsed after the initial fracture did not preclude the occurrence of consolidation. CONCLUSION: Bone consolidation was efficaciously obtained with the studied expanded hBM-MSCs combined to biomaterials, by clinical and radiological evaluation, and confirmed by bone biopsies, with lower consolidation scores in smokers.

Functional Comparison between Healthy and Multiple Myeloma Adipose Stromal Cells.

Multiple myeloma (MM) is an incurable B cell neoplasia characterized by the accumulation of tumor plasma cells within the bone marrow (BM). As a consequence, bone osteolytic lesions develop in 80% of patients and remain even after complete disease remission. We and others had demonstrated that BM-derived mesenchymal stromal cells (MSCs) are abnormal in MM and thus cannot be used for autologous treatment to repair bone damage. Adipose stromal cells (ASCs) represent an interesting alternative to MSCs for cellular therapy. Thus, in this study, we wondered whether they could be a good candidate in repairing MM bone lesions. For the first time, we present a transcriptomic, phenotypic, and functional comparison of ASCs from MM patients and healthy donors (HDs) relying on their autologous MSC counterparts. In contrast to MM MSCs, MM ASCs did not exhibit major abnormalities. However, the changes observed in MM ASCs and the supportive property of ASCs on MM cells question their putative and safety uses at an autologous or allogenic level.

Cell immaturity and white/beige adipocyte potential of primary human adipose-derived stromal cells are restrained by culture-medium TGFß1.

Human adipose-derived stem/stromal cells (hASCs) can differentiate into specialized cell types and thereby contribute to tissue regeneration. As such, hASCs have drawn increasing attention in cell therapy and regenerative medicine, not to mention the ease to isolate them from donors. Culture conditions are critical for expanding hASCs while maintaining optimal therapeutic capabilities. Here, we identified a role for transforming growth factor ß1 (TGFß1) in culture medium in influencing the fate of hASCs during in vitro cell expansion. Human ASCs obtained after expansion in standard culture medium (Standard-hASCs) and in endothelial cell growth medium 2 (EGM2-hASCs) were characterized by high-throughput transcriptional studies, gene set enrichment analysis and functional properties. EGM2-hASCs exhibited enhanced multipotency capabilities and an immature phenotype compared with Standard-hASCs. Moreover, the adipogenic potential of EGM2-hASCs was enhanced, including toward beige adipogenesis, compared with Standard-hASCs. In these conditions, TGFß1 acts as a critical factor affecting the immaturity and multipotency of Standard-hASCs, as suggested by small mother of decapentaplegic homolog 3 (SMAD3) nuclear localization and phosphorylation in Standard-hASCs vs EGM2-hASCs. Finally, the typical priming of Standard-hASCs into osteoblast, chondroblast, and vascular smooth muscle cell (VSMC) lineages was counteracted by pharmacological inhibition of the TGFß1 receptor, which allowed retention of SMAD3 into the cytoplasm and a decrease in expression of osteoblast and VSMC lineage markers. Overall, the TGFß1 pathway appears critical in influencing the commitment of hASCs toward osteoblast, chondroblast, and VSMC lineages, thus reducing their adipogenic potential. These effects can be counteracted by using EGM2 culture medium or chemical inhibition of the TGFß1 pathway.

Integrated transcriptomic, phenotypic, and functional study reveals tissue-specific immune properties of mesenchymal stromal cells.

Clinical-grade mesenchymal stromal cells (MSCs) can be expanded from bone marrow and adipose tissue to treat inflammatory diseases and degenerative disorders. However, the influence of their tissue of origin on their functional properties, including their immunosuppressive activity, remains unsolved. In this study, we produced paired bone marrow-derived mesenchymal stromal cell (BM-MSC) and adipose-derived stromal cell (ASC) batches from 14 healthy donors. We then compared them using transcriptomic, phenotypic, and functional analyses and validated our results on purified native MSCs to infer which differences were really endowed by tissue of origin. Cultured MSCs segregated together owing to their tissue of origin based on their gene expression profile analyzed using differential expression and weighted gene coexpression network analysis. This translated into distinct immune-related gene signatures, phenotypes, and functional cell interactions. Importantly, sorted native BM-MSCs and ASCs essentially displayed the same distinctive patterns than their in vitro-expanded counterparts. As a whole, ASCs exhibited an immune profile consistent with a stronger inhibition of immune response and a lower immunogenicity, supporting the use of adipose tissue as a valuable source for clinical applications.

Human adipose stromal-vascular fraction self-organizes to form vascularized adipose tissue in 3D cultures.

Native human subcutaneous adipose tissue (AT) is well organized into unilocular adipocytes interspersed within dense vascularization. This structure is completely lost under standard culture conditions and may impair the comparison with native tissue. Here, we developed a 3-D model of human white AT reminiscent of the cellular architecture found in vivo. Starting with adipose progenitors derived from the stromal-vascular fraction of human subcutaneous white AT, we generated spheroids in which endogenous endothelial cells self-assembled to form highly organized endothelial networks among stromal cells. Using an optimized adipogenic differentiation medium to preserve endothelial cells, we obtained densely vascularized spheroids containing mature adipocytes with unilocular lipid vacuoles. In vivo study showed that when differentiated spheroids were transplanted in immune-deficient mice, endothelial cells within the spheroids connected to the recipient circulatory system, forming chimeric vessels. In addition, adipocytes of human origin were still observed in transplanted mice. We therefore have developed an in vitro model of vascularized human AT-like organoids that constitute an excellent tool and model for any study of human AT.

Translation of a standardized manufacturing protocol for mesenchymal stromal cells: A systematic comparison of validation and manufacturing data.

BACKGROUND: Many data are available on expansion protocols for mesenchymal stromal cells (MSCs) for both experimental settings and manufacturing for clinical trials. However, there is a lack of information on translation of established protocols for Good Manufacturing Practice (GMP) from validation to manufacturing for clinical application. We present the validation and translation of a standardized pre-clinical protocol for isolation and expansion of MSCs for a clinical trial for reconstitution of alveolar bone. METHODS: Key parameters of 22 large-scale expansions of MSCs from bone marrow (BM) for validation were compared with 11 expansions manufactured for the clinical trial "Jaw bone reconstruction using a combination of autologous mesenchymal stromal cells and biomaterial prior to dental implant placement (MAXILLO1)" aimed at reconstruction of alveolar bone. RESULTS: Despite variations of the starting material, the robust protocol led to stable performance characteristics of expanded MSCs. Manufacturing of the autologous advanced therapy medicinal product MAXILLO-1-MSC was possible, requiring 21 days for each product. Transport of BM aspirates and MSCs within 24 h was guaranteed. MSCs fulfilled quality criteria requested by the national competent authority. In one case, the delivered MSCs developed a mosaic in chromosomal finding, showing no abnormality in differentiation capacity, growth behavior or surface marker expression during long-term culture. The proportion of cells with the mosaic decreased in long-term culture and cells stopped growth after 38.4 population doublings. CONCLUSIONS: Clinical use of freshly prepared MSCs, manufactured according to a standardized and validated protocol, is feasible for bone regeneration, even if there was a long local distance between manufacturing center and clinical site. Several parameters, such as colony forming units fibroblasts (CFU-F), percentage of CD34+ cells, cell count of mononuclear cells (MNCs) and white blood cells (WBCs), of the BM may serve as a predictive tool for the yield of MSCs and may help to avoid unnecessary costs for MSC manufacturing due to insufficient cell expansion rates.

Mass Spectrometry-based Absolute Quantification of 20S Proteasome Status for Controlled Ex-vivo Expansion of Human Adipose-derived Mesenchymal Stromal/Stem Cells.

The proteasome controls a multitude of cellular processes through protein degradation and has been identified as a therapeutic target in oncology. However, our understanding of its function and the development of specific modulators are hampered by the lack of a straightforward method to determine the overall proteasome status in biological samples. Here, we present a method to determine the absolute quantity and stoichiometry of ubiquitous and tissue-specific human 20S proteasome subtypes based on a robust, absolute SILAC-based multiplexed LC-Selected Reaction Monitoring (SRM) quantitative mass spectrometry assay with high precision, accuracy, and sensitivity. The method was initially optimized and validated by comparison with a reference ELISA assay and by analyzing the dynamics of catalytic subunits in HeLa cells following IFNγ-treatment and in range of human tissues. It was then successfully applied to reveal IFNγ- and O2-dependent variations of proteasome status during primary culture of Adipose-derived-mesenchymal Stromal/Stem Cells (ADSCs). The results show the critical importance of controlling the culture conditions during cell expansion for future therapeutic use in humans. We hypothesize that a shift from the standard proteasome to the immunoproteasome could serve as a predictor of immunosuppressive and differentiation capacities of ADSCs and, consequently, that quality control should include proteasomal quantification in addition to examining other essential cell parameters. The method presented also provides a new powerful tool to conduct more individualized protocols in cancer or inflammatory diseases where selective inhibition of the immunoproteasome has been shown to reduce side effects.

Feasibility and safety of treating non-unions in tibia, femur and humerus with autologous, expanded, bone marrow-derived mesenchymal stromal cells associated with biphasic calcium phosphate biomaterials in a multicentric, non-comparative trial.

BACKGROUND: ORTHO-1 is a European, multicentric, first in human clinical trial to prove safety and feasibility after surgical implantation of commercially available biphasic calcium phosphate bioceramic granules associated during surgery with autologous mesenchymal stromal cells expanded from bone marrow (BM-hMSC) under good manufacturing practices, in patients with long bone pseudarthrosis. METHODS: Twenty-eight patients with femur, tibia or humerus diaphyseal or metaphyso-diaphyseal non-unions were recruited and surgically treated in France, Germany, Italy and Spain with 100 or 200 million BM-hMSC/mL associated with 5-10 cc of bioceramic granules. Patients were followed up during one year. The investigational advanced therapy medicinal product (ATMP) was expanded under the same protocol in all four countries, and approved by each National Competent Authority. FINDINGS: With safety as primary end-point, no severe adverse event was reported as related to the BM-hMSC. With feasibility as secondary end-point, the participating production centres manufactured the BM-hMSC as planned. The ATMP combined to the bioceramic was surgically delivered to the non-unions, and 26/28 treated patients were found radiologically healed at one year (3 out of 4 cortices with bone bridging). INTERPRETATION: Safety and feasibility were clinically proven for surgical implantation of expanded autologous BM-hMSC with bioceramic. FUNDING: EU-FP7-HEALTH-2009, REBORNE Project (GA: 241876).

Mesenchymal Stromal Cells: Clinical Challenges and Therapeutic Opportunities.

Mesenchymal stromal cells (MSCs) have been the subject of clinical trials for more than a generation, and the outcomes of advanced clinical trials have fallen short of expectations raised by encouraging pre-clinical animal data in a wide array of disease models. In this Perspective, important biological and pharmacological disparities in pre-clinical research and human translational studies are highlighted, and analyses of clinical trial failures and recent successes provide a rational pathway to MSC regulatory approval and deployment for disorders with unmet medical needs.

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  = â€…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  = â€…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.

Inferior In Vivo Osteogenesis and Superior Angiogenesis of Human Adipose­Derived Stem Cells Compared with Bone Marrow­Derived Stem Cells Cultured in Xeno­Free Conditions.

The possibility of using adipose tissue-derived stromal cells (ATSC) as alternatives to bone marrow-derived stromal cells (BMSC) for bone repair has garnered interest due to the accessibility, high cell yield, and rapid in vitro expansion of ATSC. For clinical relevance, their bone forming potential in comparison to BMSC must be proven. Distinct differences between ATSC and BMSC have been observed in vitro and comparison of osteogenic potential in vivo is not clear to date. The aim of the current study was to compare the osteogenesis of human xenofree-expanded ATSC and BMSC in vitro and in an ectopic nude mouse model of bone formation. Human MSC were implanted with biphasic calcium phosphate biomaterials in subcutis pockets for 8 weeks. Implant groups were: BMSC, ATSC, BMSC and ATSC mixed together in different ratios, as well as MSC primed with either osteogenic supplements (250 µM ascorbic acid, 10 mM ß-glycerolphosphate, and 10 nM dexamethasone) or 50 ng/ml recombinant bone morphogenetic protein 4 prior to implantation. In vitro results show osteogenic gene expression and differentiation potentials of ATSC. Despite this, ATSC failed to form ectopic bone in vivo, in stark contrast to BMSC, although osteogenic priming did impart minor osteogenesis to ATSC. Neovascularization was enhanced by ATSC compared with BMSC; however, less ATSC engrafted into the implant compared with BMSC. Therefore, in the content of bone regeneration, the advantages of ATSC over BMSC including enhanced angiogenesis, may be negated by their lack of osteogenesis and prerequisite for osteogenic differentiation prior to transplantation. Stem Cells Translational Medicine 2017;6:2160-2172.

Rationale for Determining the Functional Potency of Mesenchymal Stem Cells in Preventing Regulated Cell Death for Therapeutic Use.

Mesenchymal stem (stromal) cells (MSCs) are being investigated for treating degenerative and inflammatory disorders because of their reparative and immunomodulatory properties. Intricate mechanisms relate cell death processes with immune responses, which have implications for degenerative and inflammatory conditions. We review the therapeutic value of MSCs in terms of preventing regulated cell death (RCD). When cells identify an insult, specific intracellular pathways are elicited for execution of RCD processes, such as apoptosis, necroptosis, and pyroptosis. To some extent, exacerbated RCD can provoke an intense inflammatory response and vice versa. Emerging studies are focusing on the molecular mechanisms deployed by MSCs to ameliorate the survival, bioenergetics, and functions of unfit immune or nonimmune cells. Given these aspects, and in light of MSC actions in modulating cell death processes, we suggest the use of novel functional in vitro assays to ensure the potency of MSCs for preventing RCD. Such analyses should be associated with existing functional assays measuring the anti-inflammatory capabilities of MSCs in vitro. MSCs selected on the basis of two in vitro functional criteria (i.e., prevention of inflammation and RCD) could possess optimal therapeutic efficacy in vivo. In addition, we underline the implications of these perspectives in clinical studies of MSC therapy, with particular focus on acute respiratory distress syndrome. Stem Cells Translational Medicine 2017;6:713-719.

CD54-Mediated Interaction with Pro-inflammatory Macrophages Increases the Immunosuppressive Function of Human Mesenchymal Stromal Cells.

Mesenchymal stromal cells (MSCs) sense and modulate inflammation and represent potential clinical treatment for immune disorders. However, many details of the bidirectional interaction of MSCs and the innate immune compartment are still unsolved. Here we describe an unconventional but functional interaction between pro-inflammatory classically activated macrophages (M1MΦ) and MSCs, with CD54 playing a central role. CD54 was upregulated and enriched specifically at the contact area between M1MФ and MSCs. Moreover, the specific interaction induced calcium signaling and increased the immunosuppressive capacities of MSCs dependent on CD54 mediation. Our data demonstrate that MSCs can detect an inflammatory microenvironment via a direct and physical interaction with innate immune cells. This finding opens different perspectives for MSC-based cell therapy.

Human Adipose-Derived Stem Cells Expanded Under Ambient Oxygen Concentration Accumulate Oxidative DNA Lesions and Experience Procarcinogenic DNA Replication Stress.

Adipose-derived stem cells (ADSCs) have led to growing interest in cell-based therapy because they can be easily harvested from an abundant tissue. ADSCs must be expanded in vitro before transplantation. This essential step causes concerns about the safety of adult stem cells in terms of potential transformation. Tumorigenesis is driven in its earliest step by DNA replication stress, which is characterized by the accumulation of stalled DNA replication forks and activation of the DNA damage response. Thus, to evaluate the safety of ADSCs during ex vivo expansion, we monitored DNA replication under atmospheric (21%) or physiologic (1%) oxygen concentration. Here, by combining immunofluorescence and DNA combing, we show that ADSCs cultured under 21% oxygen accumulate endogenous oxidative DNA lesions, which interfere with DNA replication by increasing fork stalling events, thereby leading to incomplete DNA replication and fork collapse. Moreover, we found by RNA sequencing (RNA-seq) that culture of ADSCs under atmospheric oxygen concentration leads to misexpression of cell cycle and DNA replication genes, which could contribute to DNA replication stress. Finally, analysis of acquired small nucleotide polymorphism shows that expansion of ADSCs under 21% oxygen induces a mutational bias toward deleterious transversions. Overall, our results suggest that expanding ADSCs at a low oxygen concentration could reduce the risk for DNA replication stress-associated transformation, as occurs in neoplastic tissues. Stem Cells Translational Medicine 2017;6:68-76.

Brief Report: Proteasomal Indoleamine 2,3-Dioxygenase Degradation Reduces the Immunosuppressive Potential of Clinical Grade-Mesenchymal Stromal Cells Undergoing Replicative Senescence.

Owing to their immunosuppressive properties, mesenchymal stromal cells (MSCs) obtained from bone marrow (BM-MSCs) or adipose tissue (ASCs) are considered a promising tool for cell therapy. However, important issues should be considered to ensure the reproducible production of efficient and safe clinical-grade MSCs. In particular, high expansion rate, associated with progressive senescence, was recently proposed as one of the parameters that could alter MSC functionality. In this study, we directly address the consequences of replicative senescence on BM-MSC and ASC immunomodulatory properties. We demonstrate that MSCs produced according to GMP procedures inhibit less efficiently T-cell, but not Natural Killer (NK)- and B-cell, proliferation after reaching senescence. Senescence-related loss-of-function is associated with a decreased indoleamine 2,3-dioxygenase (IDO) activity in response to inflammatory stimuli. In particular, although STAT-1-dependent IDO expression is transcriptionally induced at a similar level in senescent and nonsenescent MSCs, IDO protein is specifically degraded by the proteasome in senescent ASCs and BM-MSCs, a process that could be reversed by the MG132 proteasome inhibitor. These data encourage the use of appropriate quality controls focusing on immunosuppressive mechanisms before translating clinical-grade MSCs in the clinic. Stem Cells 2017;35:1431-1436.

Spatial and temporal structure of the clinical research based on mesenchymal stromal cells: A network analysis.

BACKGROUND AIMS: Using innovative tools derived from social network analysis, the aims of this study were (i) to decipher the spatial and temporal structure of the research centers network dedicated to the therapeutic uses of mesenchymal stromal cells (MSCs) and (ii) to measure the influence of fields of applications, cellular sources and industry funding on network topography. METHODS: From each trial using MSCs reported on ClinicalTrials.gov, all research centers were extracted. Networks were generated using Cytoscape 3.2.2, where each center was assimilated to a node, and one trial to an edge connecting two nodes. RESULTS: The analysis included 563 studies. An independent segregation was obvious between continents. Asian, South American and African centers were significantly more isolated than other centers. Isolated centers had fewer advanced phases (P <0.001), completed studies (P = 0.01) and industry-supported studies (P <0.001). Various thematic priorities among continents were identified: the cardiovascular, digestive and nervous system diseases were strongly studied by North America, Europe and Asia, respectively. The choice of cellular sources also affected the network topography; North America was primarily involved in bone-marrow-derived MSC research, whereas Europe and Asia dominated the use of adipose-derived MSCs. Industrial funding was the highest for North American centers (90.5%). CONCLUSIONS: Strengthening of international standards and statements with institutional, federal and industrial partners is necessary. More connections would facilitate the transfer of knowledge, sharing of resources, mobility of researchers and advancement of trials. Developing partnerships between industry and academic centers seems beneficial to the advancement of trials across different phases and would facilitate the translation of research discoveries.

Mechanically Isolated Stromal Vascular Fraction Provides a Valid and Useful Collagenase-Free Alternative Technique: A Comparative Study.

BACKGROUND: The use of stromal vascular fraction and adipose-derived stromal cells in tissue regeneration is now being increasingly investigated, and studies have demonstrated that adipose-derived stromal cells present differentiation and immunomodulatory capacities. The development of a rapid, inexpensive, and enzyme-free technique to isolate adipose-derived stromal cell-enriched stromal vascular fraction is a major goal for stem cell therapy. Therefore, the authors compared innovative mechanical procedures to the gold standard technique, collagenase digestion. METHODS: Stromal vascular fraction was prepared from 21 liposuctions using either enzymatic digestion or two different mechanical methods: high vortexing/centrifugation and dissociation by intersyringe processing. The effects of tissue processing on cell count, viability, proliferation, clonogenic enrichment, and the phenotypes of the different native cell were determined. Adipose-derived stromal cell phenotypes from the different protocols, and their differentiation and immunosuppressive potential, were compared. RESULTS: Enzymatic digestion isolated more viable cells than dissociation by intersyringe processing and vortexing/centrifugation. The expansion rate and clonogenic enrichment were higher for stromal vascular fraction isolated with collagenase. The proportion of adipose-derived stromal cells was higher in stromal vascular fraction extracted with dissociation than with enzymatic digestion and vortexing/centrifugation (p < 0.01). Interestingly, all cultured adipose-derived stromal cells displayed similar differentiation and immunosuppressive capacities. CONCLUSIONS: Enzymatic digestion extracts more adipose-derived stromal cells, but intersyringe dissociation enables the rapid extraction of adipose-derived stromal cell-enriched stromal vascular fraction. Moreover, mechanical methods enable adipose-derived stromal cell isolation with stemness and immunosuppressive properties, similar to enzymatic digestion. Such mechanical procedures could allow easier and more rapid isolation of adipose-derived stromal cell-enriched stromal vascular fraction for practitioners. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V.