Mesenchymal stromal cell apoptosis is required for their therapeutic function

Material-driven immunomodulation and ECM remodeling reverse pulmonary fibrosis by local delivery of stem cell-laden microcapsules

Recent progress in stem cell therapy has demonstrated the therapeutic potential of intravenous stem cell infusions for treating the life-threatening lung disease of pulmonary fibrosis (PF). However, it is confronted with limitations, such as a lack of control over cellular function and rapid clearance by the host after implantation. In this study, we developed an innovative PF therapy through tracheal administration of microfluidic-templated stem cell-laden microcapsules, which effectively reversed the progression of inflammation and fibrotic injury. Our findings highlight that hydrogel microencapsulation can enhance the persistence of donor mesenchymal stem cells (MSCs) in the host while driving MSCs to substantially augment their therapeutic functions, including immunoregulation and matrix metalloproteinase (MMP)-mediated extracellular matrix (ECM) remodeling. We revealed that microencapsulation activates the MAPK signaling pathway in MSCs to increase MMP expression, thereby degrading overexpressed collagen accumulated in fibrotic lungs. Our research demonstrates the potential of hydrogel microcapsules to enhance the therapeutic efficacy of MSCs through cell-material interactions, presenting a promising yet straightforward strategy for designing advanced stem cell therapies for fibrotic diseases.

Augmenting osteoporotic bone regeneration through a hydrogel-based rejuvenating microenvironment

Osteoporotic bone defects pose a significant challenge for bone regeneration as they exhibit impaired healing capacity and delayed healing period. To address this issue, this study introduces a hydrogel that creates a rejuvenating microenvironment, thereby facilitating efficient bone repair during the initial two weeks following bone defect surgery. The hydrogel, named GelHFS, was created through host-guest polymerization of gelatin and acrylated β-cyclodextrin. Incorporation of the human fetal mesenchymal stem cell secretome (HFS) formed GelHFS hydrogel aimed at mimicking a rejuvenated stem cell niche. Our results demonstrated that GelHFS hydrogel promotes cell stellate spreading and osteogenic differentiation via integrin β1-induced focal adhesion pathway. Implantation of GelHFS hydrogel in an osteoporotic bone defect rat model recruited endogenous integrin β1-expressing cells and enhanced new bone formation and bone strength. Our findings reveal that GelHFS hydrogel provides a rejuvenating niche for endogenous MSCs and enhances bone regeneration in osteoporotic bone defect. These findings highlight the potential of GelHFS hydrogel as an effective therapeutic strategy for addressing challenging bone healing such as osteoporotic bone regeneration.

A multi-modality imaging strategy to determine the multiple in vivo fates of human umbilical cord mesenchymal stem cells at different periods of acute liver injury treatment

Human umbilical cord mesenchymal stem cells (HUCMSCs) are applied for disease therapy as a new type of drug in many countries. Their effects are not only presented by live cells, but also apoptotic bodies or cell fragments of dead cells. Therefore, it is meaningful to determine the multiple fates of HUCMSCs in vivo. Although various probes combining different imaging modalities have been developed to label and trace transplanted HUCMSCs in vivo, the status of the cells (live, dead, or apoptotic) was not distinguished, and a thorough understanding of the multiple fates of HUCMSCs after transplantation in vivo is lacking. Therefore, a magnetic resonance (MR)/near infrared fluorescent (NIRF)/bioluminescence (BI) multi-modality imaging strategy was developed. Iron oxide nanoparticles (IONPs) were assembled into 100 nm nanoparticles using epigallocatechin gallate as a chemical linker to increase the MR signal and reduce the exocytosis of IONPs for direct cell labeling and longitudinal MR imaging tracking. Fluorescent probes for apoptosis (DEVD-Cy-OH) were also loaded in the above assemblies to monitor the cell status. Meanwhile, the cell surface was labeled with the fluorescent dye Cy7 via bioorthogonal reactions to visualize the NIRF signal. Luciferase was lentivirally transfected into live cells to generate bioluminescence. Such labeling did not affect either the viability, proliferation, migration, differentiation characteristics of HUCMSCs or their therapeutic effects on acute liver injury mice in vivo. The in vivo fates of HUCMSCs were monitored via MR/NIRF/BI multi-modality imaging in acute liver injury mice. Although MR and Cy7 signals aggregated in injured liver for 7 days, the BI signals persisted for less than 24 hours. There was an increase in DEVD-Cy-OH signals in the injured liver, but they were almost at the basal level. That means that HUCMSCs survive in mice for a short time, and the dead form of HUCMSCs accumulated in a large quantity and sustained for a long time, which might contribute to their therapeutic effect.

Innovative cell therapies for systemic sclerosis: available evidence and new perspectives

INTRODUCTION

Systemic sclerosis (SSc) is the rheumatic disease with the highest individual mortality rate with a detrimental impact on quality of life. Cell-based therapies may offer new perspectives for this disease as recent phase I trials support the safety of IV infusion of allogeneic mesenchymal stromal cells in SSc and case reports highlight the potential use of Chimeric Antigen Receptor (CAR)-T cells targeting CD19 in active SSc patients who have not responded to conventional immunosuppressive therapies.

AREAS COVERED

This narrative review highlights the most recent evidence supporting the use of cellular therapies in SSc as well as their potential mechanisms of action and discusses future perspectives for cell-based therapies in SSc. Medline/PubMed was used to identify the articles of interest, using the keywords 'Cellular therapies,' 'Mesenchymal stromal cells,' 'Chimeric Antigen Receptor' AND 'systemic sclerosis.' Milestones articles reported by the authors were also used.

EXPERT OPINION

Cellular therapies may represent an opportunity for long-term remission/cure in patients with different autoimmune diseases, including SSc who have not responded to conventional therapies. Multiple ongoing phase I/II trials will provide greater insights into the efficacy and toxicity of cellular therapies.

The Effects of the Pneumonia Lung Microenvironment on MSC Function

BACKGROUND

Despite promise in preclinical models of acute respiratory distress syndrome (ARDS), mesenchymal stem cells (MSC) have failed to translate to therapeutic benefit in clinical trials. The MSC is a live cell medicine and interacts with the patient's disease state. Here, we explored this interaction, seeking to devise strategies to enhance MSC therapeutic function.

METHODS

Human bone-marrow-derived MSCs were exposed to lung homogenate from healthy and E. coli-induced ARDS rat models. Apoptosis and functional assays of the MSCs were performed.

RESULTS

The ARDS model showed reduced arterial oxygenation, decreased lung compliance and an inflammatory microenvironment compared to controls. MSCs underwent more apoptosis after stimulation by lung homogenate from controls compared to E. coli, which may explain why MSCs persist longer in ARDS subjects after administration. Changes in expression of cell surface markers and cytokines were associated with lung homogenate from different groups. The anti-microbial effects of MSCs did not change with the stimulation. Moreover, the conditioned media from lung-homogenate-stimulated MSCs inhibited T-cell proliferation.

CONCLUSIONS

These findings suggest that the ARDS microenvironment plays an important role in the MSC's therapeutic mechanism of action, and changes can inform strategies to modulate MSC-based cell therapy for ARDS.

Pharmacokinetic characteristics of mesenchymal stem cells in translational challenges

Over the past two decades, mesenchymal stem/stromal cell (MSC) therapy has made substantial strides, transitioning from experimental clinical applications to commercial products. MSC therapies hold considerable promise for treating refractory and critical conditions such as acute graft-versus-host disease, amyotrophic lateral sclerosis, and acute respiratory distress syndrome. Despite recent successes in clinical and commercial applications, MSC therapy still faces challenges when used as a commercial product. Current detection methods have limitations, leaving the dynamic biodistribution, persistence in injured tissues, and ultimate fate of MSCs in patients unclear. Clarifying the relationship between the pharmacokinetic characteristics of MSCs and their therapeutic effects is crucial for patient stratification and the formulation of precise therapeutic regimens. Moreover, the development of advanced imaging and tracking technologies is essential to address these clinical challenges. This review provides a comprehensive analysis of the kinetic properties, key regulatory molecules, different fates, and detection methods relevant to MSCs and discusses concerns in evaluating MSC druggability from the perspective of integrating pharmacokinetics and efficacy. A better understanding of these challenges could improve MSC clinical efficacy and speed up the introduction of MSC therapy products to the market.

Evidence-Based Clinical Practice Guidelines on Regenerative Medicine Treatment for Chronic Pain: A Consensus Report from a Multispecialty Working Group

Purpose

Injectable biologics have not only been described and developed to treat dermal wounds, cardiovascular disease, and cancer, but have also been reported to treat chronic pain conditions. Despite emerging evidence supporting regenerative medicine therapy for pain, many aspects remain controversial.

Methods

The American Society of Pain and Neuroscience (ASPN) identified the educational need for an evidence-based guideline on regenerative medicine therapy for chronic pain. The executive board nominated experts spanning multiple specialties including anesthesiology, physical medicine and rehabilitation, and sports medicine based on expertise, publications, research, and clinical practice. A steering committee selected preliminary questions, which were reviewed and refined. Evidence was appraised using the United States Preventive Services Task Force (USPSTF) criteria for evidence level and degree of recommendation. Using a modified Delphi approach, consensus points were distributed to all collaborators and each collaborator voted on each point. If collaborators provided a decision of "disagree" or "abstain", they were invited to provide a rationale in a non-blinded fashion to the committee chair, who incorporated the respective comments and distributed revised versions to the committee until consensus was achieved.

Results

Sixteen questions were selected for guideline development. Questions that were addressed included type of injectable biologics and mechanism, evidence in treating chronic pain indications (eg, tendinopathy, muscular pathology, osteoarthritis, intervertebral disc disease, neuropathic pain), role in surgical augmentation, dosing, comparative efficacy between injectable biologics, peri-procedural practices to optimize therapeutic response and quality of injectate, federal regulations, and complications with mitigating strategies.

Conclusion

In well-selected individuals with certain chronic pain indications, use of injectable biologics may provide superior analgesia, functionality, and/or quality of life compared to conventional medical management or placebo. Future high-quality randomized clinical trials are warranted with implementation of minimum reporting standards, standardization of preparation protocols, investigation of dose-response associations, and comparative analysis between different injectable biologics.

Liposomal sodium clodronate mitigates radiation-induced lung injury through macrophage depletion

Radiation-induced lung injury (RILI) is a severe complication arising from thoracic tumor radiotherapy, which constrains the possibility of increasing radiation dosage. Current RILI therapies provide only limited relief and may result in undesirable side effects. Therefore, there is an urgent demand for effective and low-toxicity treatments for RILI. Macrophages play a pivotal role in RILI, promoting inflammation in the initial stages and facilitating fibrosis in the later stages. Sodium clodronate, a bisphosphonate, can induce macrophage apoptosis when encapsulated in liposomes. In this study, we explored the potential of liposomal sodium clodronate (LC) as a specific agent for depleting macrophages to alleviate acute RILI. We assessed the impact of LC on macrophage consumption both in vitro and in vivo. In a mouse model of acute RILI, LC treatment group led to a reduction in alveolar macrophage counts, mitigated lung injury severity, and lowered levels of pro-inflammatory cytokines in both plasma and bronchoalveolar lavage fluid. Additionally, we further elucidated the specific effects and mechanism of LC on macrophages in vitro. Alveolar macrophages MHS cells were subjected to varying concentrations of LC (0, 50, 100, 200 μg/ml), and the results demonstrated its dose-dependent inhibition of cell proliferation and induction of apoptosis. Moreover, LC decreased the secretion of pro-inflammatory cytokines, including IL-1β, IL-6, and TNF-α. Conditioned media from LC-treated macrophages protected alveolar epithelial cells MLE-12 from radiation-induced damage, as demonstrated by reduced apoptosis and DNA damage. These findings imply that LC-mediated macrophage depletion may present a promising therapeutic strategy for alleviating radiation-induced lung injury.

Stem cells, cell therapies, and bioengineering in lung biology and diseases 2023

Repair and regeneration of a diseased lung using stem cells or bioengineered tissues is an exciting therapeutic approach for a variety of lung diseases and critical illnesses. Over the past decade, increasing evidence from preclinical models suggests that mesenchymal stromal cells, which are not normally resident in the lung, can be used to modulate immune responses after injury, but there have been challenges in translating these promising findings to the clinic. In parallel, there has been a surge in bioengineering studies investigating the use of artificial and acellular lung matrices as scaffolds for three-dimensional lung or airway regeneration, with some recent attempts of transplantation in large animal models. The combination of these studies with those involving stem cells, induced pluripotent stem cell derivatives, and/or cell therapies is a promising and rapidly developing research area. These studies have been further paralleled by significant increases in our understanding of the molecular and cellular events by which endogenous lung stem and/or progenitor cells arise during lung development and participate in normal and pathological remodeling after lung injury. For the 2023 Stem Cells, Cell Therapies, and Bioengineering in Lung Biology and Diseases Conference, scientific symposia were chosen to reflect the most cutting-edge advances in these fields. Sessions focused on the integration of "omics" technologies with function, the influence of immune cells on regeneration, and the role of the extracellular matrix in regeneration. The necessity for basic science studies to enhance fundamental understanding of lung regeneration and to design innovative translational studies was reinforced throughout the conference.

Hinokiflavone resists HFD-induced obesity by promoting apoptosis in an IGF2BP2-mediated Bim m6A modification dependent manner

Obesity has emerged as a major health risk on a global scale. Hinokiflavone (HF), a natural small molecule, extracted from plants like cypress, exhibits diverse chemical structures and low synthesis costs. Using high-fat diet-induced obese mice models, we found that HF suppresses obesity by inducing apoptosis in adipose tissue. Adipocyte apoptosis helps maintain tissue health by removing aging, damaged, or excess cells in adipose tissue, which is crucial in preventing obesity and metabolic diseases. We found that HF can specifically bind to insulin-like growth factor 2 mRNA binding protein 2 to promote the stability of N6-methyladenosine-modified Bim, inducing mitochondrial outer membrane permeabilization. Mitochondrial outer membrane permeabilization leads to Caspase9/3-mediated adipocyte mitochondrial apoptosis, alleviating obesity induced by a high-fat diet. The proapoptotic effect of HF offers a controlled means for weight loss. This study reveals the potential of small molecule HF in developing new therapeutic approaches in drug development and biomedical research.

Potential use of stem cell therapies for treating osteoarthritis and rheumatoid arthritis

Arthritis, defined as a chronic inflammation often accompanied by swelling of one or more joints, encompasses more than 100 conditions that affect the joints, tissues around them as well as other connective tissues. This condition causes severe discomfort compromising the quality of life drastically, and thereby inflicts severe financial and social impact on the people affected. The incidence rate of arthritis is increasing all around the globe including the United States every year. In general, osteoarthritis (OA) affects more people in comparison to rheumatoid arthritis (RA). In the USA itself, more than 14 million people are affected by OA in comparison to 1.4 million people suffering from RA. In both conditions, elevated levels of proinflammatory cytokines have been recorded, this incidence generally precedes the cartilage degradation observed in the patients. The use of mesenchymal stem cells (MSCs) has proven to be a safe and efficient therapeutic option for treating many inflammation-rooted pathological conditions. Evidence suggests that MSCs down-regulate the effects of proinflammatory cytokines including tumor necrosis factor (TNF)-α, interferon (IFN)-γ, interleukin (IL)-1B, IL-2, and IL-17, and help restore the functions of immune cells. In addition, these cells promote the polarization of M2 phenotype macrophages, thus contributing to the suppression of the inflammatory process and consequentially to cartilage regeneration. Preclinical and clinical trials have proven the safety and effectiveness of this therapy, supported by the fact that these do not provoke any host immune response, and their influence on the cytokine profiles. An attempt to survey the results of stem cell therapy for treating arthritis has been carried out in this review.

The autophagy protein RUBCNL/PACER represses RIPK1 kinase-dependent apoptosis and necroptosis

Mesenchymal stem cells (MSCs) are used in cell therapy; nonetheless, their application is limited by their poor survival after transplantation in a proinflammatory microenvironment. Macroautophagy/autophagy activation in MSCs constitutes a stress adaptation pathway, promoting cellular homeostasis. Our proteomics data indicate that RUBCNL/PACER (RUN and cysteine rich domain containing beclin 1 interacting protein like), a positive regulator of autophagy, is also involved in cell death. Hence, we screened MSC survival upon various cell death stimuli under loss or gain of function of RUBCNL. MSCs were protected from TNF (tumor necrosis factor)-induced regulated cell death when RUBCNL was expressed. TNF promotes inflammation by inducing RIPK1 kinase-dependent apoptosis or necroptosis. We determine that MSCs succumb to RIPK1 kinase-dependent apoptosis upon TNF sensing and necroptosis when caspases are inactivated. We show that RUBCNL is a negative regulator of both RIPK1-dependent apoptosis and necroptosis. Furthermore, RUBCNL mutants that lose the ability to regulate autophagy, retain their function in negatively regulating cell death. We also found that RUBCNL forms a complex with RIPK1, which disassembles in response to TNF. In line with this finding, RUBCNL expression limits assembly of RIPK1-TNFRSF1A/TNFR1 complex I, suggesting that complex formation between RUBCNL and RIPK1 represses TNF signaling. These results provide new insights into the crosstalk between the RIPK1-mediated cell death and autophagy machineries and suggest that RUBCNL, due to its functional duality in autophagy and apoptosis/necroptosis, could be targeted to improve the therapeutic efficacy of MSCs. Abbreviations: BAF: bafilomycin A1; CASP3: caspase 3; Caspases: cysteine-aspartic proteases; cCASP3: cleaved CASP3; CQ: chloroquine; CHX: cycloheximide; cPARP: cleaved poly (ADP-ribose) polymerase; DEPs: differential expressed proteins; ETO: etoposide; MEF: mouse embryonic fibroblast; MLKL: mixed lineage kinase domain-like; MSC: mesenchymal stem cell; MTORC1: mechanistic target of rapamycin kinase complex 1; Nec1s: necrostatin 1s; NFKB/NF-kB: nuclear factor of kappa light polypeptide gene enhancer in B cells; PLA: proximity ligation assay; RCD: regulated cell death; RIPK1: receptor (TNFRSF)-interacting serine-threonine kinase 1; RIPK3: receptor-interacting serine-threonine kinase 3; RUBCNL/PACER: RUN and cysteine rich domain containing beclin 1 interacting protein like; siCtrl: small interfering RNA nonsense; siRNA: small interfering RNA; TdT: terminal deoxynucleotidyl transferase; Tm: tunicamycin; TNF: tumor necrosis factor; TNFRSF1A/TNFR1: tumor necrosis factor receptor superfamily, member 1a.

Dexamethasone-Integrated Mesenchymal Stem Cells for Systemic Lupus Erythematosus Treatment via Multiple Immunomodulatory Mechanisms

The therapeutic application of mesenchymal stem cells (MSCs) has good potential as a treatment strategy for systemic lupus erythematosus (SLE), but traditional MSC therapy still has limitations in effectively modulating immune cells. Herein, we present a promising strategy based on dexamethasone liposome-integrated MSCs (Dexlip-MSCs) for treating SLE via multiple immunomodulatory pathways. This therapeutic strategy prolonged the circulation time of dexamethasone liposomes in vivo, restrained CD4+T-cell proliferation, and inhibited the release of proinflammatory mediators (IFN-γ and TNF-α) by CD4+T cells. In addition, Dexlip-MSCs initiated cellular reprogramming by activating the glucocorticoid receptor (GR) signaling pathway to upregulate the expression of anti-inflammatory factors such as cysteine-rich secretory protein LCCL-containing domain 2 (CRISPLD2) and downregulate the expression of proinflammatory factors. In addition, Dexlip-MSCs synergistically increased the anti-inflammatory inhibitory effect of CD4+T cells through the release of dexamethasone liposomes or Dex-integrated MSC-derived exosomes (Dex-MSC-EXOs). Based on these synergistic biological effects, we demonstrated that Dexlip-MSCs alleviated disease progression in MRL/lpr mice more effectively than Dexlip or MSCs alone. These features indicate that our stem cell delivery strategy is a promising therapeutic approach for clinical SLE treatment.

Integration of network pharmacology and experimental verifications reveals the Bian-Se-Tong mixture can alleviate constipation in STC rats by reducing apoptosis of Cajal cells via activating PI3K-Akt signaling pathway

Bian-Se-Tong mixture (BSTM) is an optimized formulation based on the classical prescription "Zhizhu pill", which is widely used in the clinical treatment of slow-transit constipation (STC). The potential molecular mechanism of BSTM therapy for STC was investigated by network pharmacology prediction combined with animal experiments. The active components of BSTM were screened via the TCMSP platform. The GeneCards, OMIM and DrugBank databases were used to search for STC targets. With the help of the Biogenet tool, a protein interaction network between drugs and disease targets was constructed, and the intersection network of the two was extracted to obtain the key targets of BSTM in the treatment of STC. GO and KEGG enrichment analyses of key targets were carried out with Metascape. Loperamide hydrochloride was used to establish an STC rat model, and the key targets and related pathways were preliminarily verified. The important signaling pathways included the PI3K-Akt, MAPK, IL-17, cAMP, and cell cycle signaling pathways. The experimental results showed that BSTM treatment increased the body weight of STC rats and increased the fecal particle number, fecal water content and intestinal carbon ink promotion rate within 24 h. Further pathological changes in the colon of the rats were also observed. In-depth mechanistic studies have shown that BSTM can significantly reduce the apoptosis of intestinal Cajal cells, downregulate the expression of Bax and c-Caspase 3, upregulate the expression of Bcl-2 and c-kit, and promote the phosphorylation of AKT. The results showed that BSTM can significantly relieve constipation in STC rats via a mechanism related to activating the PI3K-Akt signaling pathway and improving Cajal cell apoptosis.

Optimizing cryopreservation conditions for use of fucosylated human mesenchymal stromal cells in anti-inflammatory/immunomodulatory therapeutics

Mesenchymal stem/stromal cells (MSCs) are being increasingly used in cell-based therapies due to their broad anti-inflammatory and immunomodulatory properties. Intravascularly-administered MSCs do not efficiently migrate to sites of inflammation/immunopathology, but this shortfall has been overcome by cell surface enzymatic fucosylation to engender expression of the potent E-selectin ligand HCELL. In applications of cell-based therapies, cryopreservation enables stability in both storage and transport of the produced cells from the manufacturing facility to the point of care. However, it has been reported that cryopreservation and thawing dampens their immunomodulatory/anti-inflammatory activity even after a reactivation/reconditioning step. To address this issue, we employed a variety of methods to cryopreserve and thaw fucosylated human MSCs derived from either bone marrow or adipose tissue sources. We then evaluated their immunosuppressive properties, cell viability, morphology, proliferation kinetics, immunophenotype, senescence, and osteogenic and adipogenic differentiation. Our studies provide new insights into the immunobiology of cryopreserved and thawed MSCs and offer a readily applicable approach to optimize the use of fucosylated human allogeneic MSCs as immunomodulatory/anti-inflammatory therapeutics.

Development of a Mouse Experimental System for the In Vivo Characterization of Bioengineered Adipose-Derived Stromal Cells

Human adipose-derived stromal cells (ADSCs) are an important resource for cell-based therapies. However, the dynamics of ADSCs after transplantation and their mechanisms of action in recipients remain unclear. Herein, we generated genetically engineered mouse ADSCs to clarify their biodistribution and post-transplantation status and to analyze their role in recipient mesenchymal tissue modeling. Immortalized ADSCs (iADSCs) retained ADSC characteristics such as stromal marker gene expression and differentiation potential. iADSCs expressing a fluorescent reporter gene were seeded into biocompatible nonwoven fabric sheets and transplanted into the dorsal subcutaneous region of neonatal mice. Transplanted donor ADSCs were distributed as CD90-positive stromal cells on the sheets and survived 1 month after transplantation. Although accumulation of T lymphocytes or macrophages inside the sheet was not observed with or without donor cells, earlier migration and accumulation of recipient blood vascular endothelial cells (ECs) inside the sheet was observed in the presence of donor cells. Thus, our mouse model can help in studying the interplay between donor ADSCs and recipient cells over a 1-month period. This system may be of value for assessing and screening bioengineered ADSCs in vivo for optimal cell-based therapies.

Apoptotic Extracellular Vesicles Induced Endothelial Cell-Mediated Autologous Stem Cell Recruitment Dominates Allogeneic Stem Cell Therapeutic Mechanism for Bone Repair

Although stem cell therapy is proved to be a promising strategy for bone repair and regeneration, transplanted allogeneic stem cells generally suffer from unfavorable apoptosis instead of differentiation into osteocytes. How the apoptotic stem cells promote bone regeneration still needs to be uncovered. In this work, we found that apoptotic extracellular vesicles released by allogeneic stem cells are critical mediators for promoting bone regeneration. Based on the results of in vivo experiments, a mechanism of apoptotic stem cells determined autologous stem cell recruitment and enhance osteogenesis was proposed. The nanoscaled apoptotic extracellular vesicles released from transplanted stem cells were endocytosed by vascular endothelial cells and preferentially distribute at endoplasmic reticular region. The oxidized phosphatidylcholine enriched in the vesicles activated the endoplasmic reticulum stress and triggered the reflective elevation of adhesion molecules, which induced the recruitment of autologous stem cells located in the blood vessels, transported them into the defect region, and promoted osteogenesis and bone repair. These findings not only reveal the mechanism of stem cell therapy of bone defects but also provide a cue for investigation of the biological process of stem cell therapy for other diseases and develop stem cell therapeutic strategies.

A1-reprogrammed mesenchymal stromal cells prime potent antitumoral responses

Mesenchymal stromal cells (MSCs) have been modified via genetic or pharmacological engineering into potent antigen-presenting cells-like capable of priming responding CD8 T cells. In this study, our screening of a variant library of Accum molecule revealed a molecule (A1) capable of eliciting antigen cross-presentation properties in MSCs. A1-reprogrammed MSCs (ARM) exhibited improved soluble antigen uptake and processing. Our comprehensive analysis, encompassing cross-presentation assays and molecular profiling, among other cellular investigations, elucidated A1's impact on endosomal escape, reactive oxygen species production, and cytokine secretion. By evaluating ARM-based cellular vaccine in mouse models of lymphoma and melanoma, we observe significant therapeutic potency, particularly in allogeneic setting and in combination with anti-PD-1 immune checkpoint inhibitor. Overall, this study introduces a strong target for developing an antigen-adaptable vaccination platform, capable of synergizing with immune checkpoint blockers to trigger tumor regression, supporting further investigation of ARMs as an effective and versatile anti-cancer vaccine.

Comparative transcriptomic analysis of bovine mesenchymal stromal cells reveals tissue-source and species-specific differences

Mesenchymal stromal cells (MSCs) have the potential to be used as therapeutics, but their efficacy varies due to cellular heterogeneity, which is not fully understood. After characterizing donor-matched bovine MSC from adipose tissue (AT), bone marrow (BM), and peripheral blood (PB), we performed single-cell RNA sequencing (scRNA-seq) to evaluate overarching similarities and differences across these three tissue-derived MSCs. Next, the transcriptomic profiles of the bovine MSCs were compared to those of equine MSCs, derived from the same tissue sources and previously published by our group, and revealed species-specific differences. Finally, the transcriptomic profile from bovine BM-MSCs was compared to mouse and human BM-MSCs and demonstrated that bovine BM-MSCs share more common functionally relevant gene expression profiles with human BM-MSCs than compared to murine BM-MSCs. Collectively, this study presents the cow as a potential non-traditional animal model for translational MSC studies based on transcriptomic profiles similar to human MSCs.

Balancing macrophage polarization via stem cell-derived apoptotic bodies for diabetic wound healing

BACKGROUND

Adipose tissue-derived stem cell-derived apoptotic bodies (ADSC-ABs) have shown great potential for immunomodulation and regeneration, particularly in diabetic wound therapy. However, their local application has been limited by unclear regulatory mechanisms, rapid clearance, and short tissue retention times.

METHODS

We analyzed the key role molecules and regulatory pathways of ADSC-ABs in regulating inflammatory macrophages by mRNA sequencing and microRNA (miRNA) sequencing and then verified them by gene knockdown. To prevent rapid clearance, we employed microfluidics technology to prepare methacrylate-anhydride gelatin (GelMA) microspheres (GMS) for controlled release of ABs. Finally, we evaluated the effectiveness of ADSC-AB-laden GMSs (ABs@GMSs) in a diabetic rat wound model.

FINDINGS

Our results demonstrated that ADSC-ABs effectively balanced macrophage inflammatory polarization through the janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway, mediated by miR-20a-5p. Furthermore, we showed that AB@GMSs had good biocompatibility, significantly delayed local clearance of ABs, and ameliorated diabetic wound inflammation and promoted vascularization, thus facilitating its healing.

CONCLUSIONS

Our study reveals the regulatory mechanism of ADSC-ABs in balancing macrophage inflammatory polarization and highlightsthe importance of delaying their local clearance by GMSs. These findings have important implications for the development of novel therapies for diabetic wound healing.

FUNDING

This research was supported by the National Key Research and Development Program of China (2020YFA0908200), National Natural Science Foundation of China (82272263, 82002053, 32000937, and 82202467), Shanghai "Rising Stars of Medical Talents" Youth Development Program (22MC1940300), Shanghai Municipal Health Commission (20204Y0354), and Shanghai Science and Technology Development Funds (22YF1421400).

ASC-expressing pyroptotic extracellular vesicles alleviate sepsis by protecting B cells

Pyroptosis is an inflammatory programmed cell death process characterized by membrane rupture. Interestingly, pyroptotic cells can generate plenty of nanosized vesicles. Non-inflammatory apoptotic cell death-derived apoptotic vesicles (apoVs) were systemically characterized and displayed multiple physiological functions and therapeutic potentials. However, the characteristics of pyroptotic cell-generated extracellular vesicles (EVs) are largely unknown. Here, we identified a group of pyroptotic EVs (pyroEVs) from in vitro cultured pyroptotic mesenchymal stem cells (MSCs), as well as from septic mouse blood. Compared with apoVs, pyroEVs express similar levels of annexin V, calreticulin, and common EV markers, but express a decreased level of apoptotic marker cleave caspase-3. PyroEVs, but not apoVs and exosomes, specifically express pyroptotic maker apoptosis-associated speck-like protein containing CARD (ASC). More importantly, MSC-derived pyroEVs protect B cells in the spleen and bone marrow to relieve inflammatory responses and enhance the survival rate of the septic mice. Mechanistically, pyroEV membrane-expressed ASC binds to B cells to repress cell death by repressing Toll-like receptor 4. This study uncovered the characteristics of pyroEVs and their therapeutic role in sepsis and B cell-mediated immune response.

Freeze-Dried Mesenchymal Stem Cells: From Bench to Bedside. Review

This review describes the freeze-dried mesenchymal stem cells (MSCs) and their ability to restore damaged tissues and organs. An analysis of the literature shows that after the lyophilization MSCs retain >80% of paracrine factors and that the mechanism of their action on the restoration of damaged tissues and organs is similar to the mechanism of action of paracrine factors in fresh and cryopreserved mesenchymal stem cells. Based on the own materials, the use of paracrine factors of freeze-dried MSCs in vivo and in vitro for the treatment of various diseases of organs and tissues has shown to be effective. The study also discusses about the advantages and disadvantages of freeze-dried MSCs versus cryopreserved MSCs. However, for the effective use of freeze-dried MSCs in clinical practice, a more detailed study of the mechanism of interaction of paracrine factors of freeze-dried MSCs with target cells and tissues is required. It is also necessary to identify possible other specific paracrine factors of freeze-dried MSCs. In addition, develop new therapeutic strategies for the use of freeze-dried MSCs in regenerative medicine and tissue bioengineering.

HIF-1α regulates the cell viability in radioiodine-resistant papillary thyroid carcinoma cells induced by hypoxia through PKM2/NF-κB signaling pathway

The curative treatment options for papillary thyroid cancer (PTC) encompass surgical intervention, radioactive iodine administration, and chemotherapy. However, the challenges of radioiodine (RAI) resistance, metastasis, and chemotherapy resistance remain inadequately addressed. The objective of this study was to investigate the protective role of hypoxia-inducible factor-1α (HIF-1α) in 131 I-resistant cells and a xenograft model under hypoxic conditions, as well as to explore potential mechanisms. The effects of HIF-1α on 131 I-resistant BCPAP and TPC-1 cells, as well as the xenograft model, were assessed in this study. Cell viability, migration, invasion, and apoptosis rates were measured using Cell Counting Kit-8, wound-healing, Transwell, and flow cytometry assays. Additionally, the expressions of Ki67, matrix metalloproteinase-9 (MMP-9), and pyruvate kinase M2 (PKM2) were examined using immunofluorescence or immunohistochemistry assays. Sodium iodide symporter and PKM2/NF-κBp65 relative protein levels were detected by western blot analysis. The findings of our study indicate that siHIF-1α effectively inhibits cell proliferation, cell migration, and invasion in 131 I-resistant cells under hypoxic conditions. Additionally, the treatment of siHIF-1α leads to alterations in the relative protein levels of Ki67, MMP-9, PKM2, and PKM2/NF-κBp65, both in vivo and in vitro. Notably, the effects of siHIF-1α are modified when DASA-58, an activator of PKM2, is administered. These results collectively demonstrate that siHIF-1α reduces cell viability in PTC cells and rat models, while also mediating the nuclear factor-κB (NF-κB)/PKM2 signaling pathway. Our findings provide a new rationale for further academic and clinical research on RAI-resistant PTC.

Study of the effect of keap1 on oxidative stress in human umbilical cord mesenchymal stem cells

BACKGROUND

HucMSCs had shown promising efficacy in treating childhood diseases, but oxidative stress induced by the poor microenvironment at the site of damage resulted in low cell survival after transplantation, thus preventing the cells from maximizing therapeutic efficacy. Therefore, this study aimed to investigate the role and mechanism of keap1 in oxidative stress injury of human umbilical cord mesenchymal stem cells (hucMSCs), and to provide theoretical support for improving the efficacy of stem cell therapy.

METHODS

The hucMSCs were treated with hypoxic low-sugar-free serum (GSDH) to mimic the damaged site microenvironment after implantation. Adenoviral overexpression of keap1 gene of hucMSCs was performed in vitro, and cell proliferation ability was detected by CCK8 assay, crystal violet staining assay, and cell cycle assay. Cellular redox level was assessed by Amplex Red, MDA, and GSH/GSSG kit. Mitochondrial morphology was evaluated by mitotracker Red staining. ATP production was estimated by ATP detection kit. The mRNA and protein expression levels were tested by western blotting and RT-qPCR.

RESULTS

GSDH treatment substantially upregulated keap1 expression. Subsequently, we found that overexpression of keap1 notably inhibited cell proliferation and caused cells to stagnate in G1 phase. At the same time, overexpression of keap1 induced the production of large amounts of H2O2 and the accumulation of MDA, but suppressed the GSH/GSSG ratio and the expression of antioxidant proteins NQO1 and SOD1, which caused oxidative stress damage. Overexpression of keap1 induced cells to produce a large number of dysfunctional mitochondria resulting in reduced ATP production. Moreover, Overexpression of keap1 significantly decreased the IKKβ protein level, while upregulating IkB mRNA levels and downregulating P50 mRNA levels.

CONCLUSIONS

Overexpression of keap1 may induce oxidative stress injury in hucMSCs by down-regulating IKKβ expression and inhibiting NF-κB pathway activation. This implies the importance of keap1 in hucMSCs and it may be a potential gene for genetic modification of hucMSCs.

The Role of Mesenchymal Stem/Stromal Cells Secretome in Macrophage Polarization: Perspectives on Treating Inflammatory Diseases

Mesenchymal stem/stromal cells (MSCs) have exhibited potential for treating multiple inflammation- related diseases (IRDs) due to their easy acquisition, unique immunomodulatory and tissue repair properties, and immune-privileged characteristics. It is worth mentioning that MSCs release a wide array of soluble bioactive components in the secretome that modulate host innate and adaptive immune responses and promote the resolution of inflammation. As the first line of defense, macrophages exist throughout the entire inflammation process. They continuously switch their molecular phenotypes accompanied by complementary functional regulation ranging from classically activated pro-inflammatory M1-type (M1) to alternatively activated anti-inflammatory M2-type macrophages (M2). Recent studies have shown that the active intercommunication between MSCs and macrophages is indispensable for the immunomodulatory and regenerative behavior of MSCs in pharmacological cell therapy products. In this review, we systematically summarized the emerging capacities and detailed the molecular mechanisms of the MSC-derived secretome (MSC-SE) in immunomodulating macrophage polarization and preventing excessive inflammation, providing novel insights into the clinical applications of MSC-based therapy in IRD management.

Anti-Proliferative and Apoptotic Activities of Rumex crispus

Colorectal cancer is the fourth leading cause of cancer death and the third most common cancer diagnosed in the United States. Several anticancer compounds from natural products have been of great interest in cancer chemotherapy and are currently in clinical trials. Natural products that present the targeted killing of cancerous cell and are soluble in water with minimal side effects are ideal candidates. In this study, water-soluble compounds from Rumex crispus plants were screened for anti-proliferative and apoptotic activity against human colorectal adenocarcinoma (DLD-1) cells. The most potent fraction with the highest cell killing and caspase fold change rates was selected for further experiments. The observed changes were further validated by measuring the caspase fold change using RT-qPCR. Furthermore, gene transcript levels were evaluated using an RT2 Profiler assay and a microarray experiment. Our results showed that the most potent L19 fraction exhibits anti-proliferative activity in a dose-dependent manner. The L19 fraction was found to induce apoptotic pathways by triggering different caspases and inflammatory pathways through the activation of non-apoptotic genes. Our study identified and validated the anticancer property of the L19 fraction, which can serve as a strong lead compound for the synthesis of other novel potent analogues.

Advancements in the pathogenesis of hepatic osteodystrophy and the potential therapeutic of mesenchymal stromal cells

Hepatic osteodystrophy (HOD) is a metabolically associated bone disease mainly manifested as osteoporosis with the characteristic of bone loss induced by chronic liver disease (CLD). Due to its high incidence in CLD patients and increased risk of fracture, the research on HOD has received considerable interest. The specific pathogenesis of HOD has not been fully revealed. While it is widely believed that disturbance of hormone level, abnormal secretion of cytokines and damage of intestinal barrier caused by CLD might jointly affect the bone metabolic balance of bone formation and bone absorption. At present, the treatment of HOD is mainly to alleviate the bone loss by drug treatment, but the efficacy and safety are not satisfactory. Mesenchymal stromal cells (MSCs) are cells with multidirectional differentiation potential, cell transplantation therapy based on MSCs is an emerging therapeutic approach. This review mainly summarized the pathogenesis and treatment of HOD, reviewed the research progress of MSCs therapy and the combination of MSCs and scaffolds in the application of osteoporotic bone defects, and discussed the potential and limitations of MSCs therapy, providing theoretical basis for subsequent studies.

Apoptosis in mesenchymal stromal cells activates an immunosuppressive secretome predicting clinical response in Crohn's disease

In vivo apoptosis of human mesenchymal stromal cells (MSCs) plays a critical role in delivering immunomodulation. Yet, caspase activity not only mediates the dying process but also death-independent functions that may shape the immunogenicity of apoptotic cells. Therefore, a better characterization of the immunological profile of apoptotic MSCs (ApoMSCs) could shed light on their mechanistic action and therapeutic applications. We analyzed the transcriptomes of MSCs undergoing apoptosis and identified several immunomodulatory factors and chemokines dependent on caspase activation following Fas stimulation. The ApoMSC secretome inhibited human T cell proliferation and activation, and chemoattracted monocytes in vitro. Both immunomodulatory activities were dependent on the cyclooxygenase2 (COX2)/prostaglandin E2 (PGE2) axis. To assess the clinical relevance of ApoMSC signature, we used the peripheral blood mononuclear cells (PBMCs) from a cohort of fistulizing Crohn's disease (CD) patients who had undergone MSC treatment (ADMIRE-CD). Compared with healthy donors, MSCs exposed to patients' PBMCs underwent apoptosis and released PGE2 in a caspase-dependent manner. Both PGE2 and apoptosis were significantly associated with clinical responses to MSCs. Our findings identify a new mechanism whereby caspase activation delivers ApoMSC immunosuppression. Remarkably, such molecular signatures could implicate translational tools for predicting patients' clinical responses to MSC therapy in CD.

Immunomodulatory function of licensed human bone marrow mesenchymal stromal cell-derived apoptotic bodies

BACKGROUND

Mesenchymal stromal cells (MSCs) show great potential for immunomodulatory and anti-inflammatory treatments. Clinical trials have been performed for the treatment of Type 1 diabetes, graft-versus-host disease and organ transplantation, which offer a promise of MSCs as an immunomodulatory therapy. Nevertheless, their unstable efficacy and immunogenicity concerns present challenges to clinical translation. It has emerged that the MSC-derived secretome, which includes secreted proteins, exosomes, apoptotic bodies (ABs) and other macromolecules, may have similar therapeutic effects to parent MSCs. Among all of the components of the MSC-derived secretome, most interest thus far has been garnered by exosomes for their therapeutic potential. However, since MSCs were reported to undergo apoptosis after in vivo transplantation and release ABs, we speculated as to whether ABs have immunomodulatory effects. In this study, cytokine licensing was used to enhance the immunomodulatory potency of MSCs and ABs derived from licensed MSCs in vitro were isolated to explore their immunomodulatory effects as an effective non-viable cell therapy.

RESULTS

IFN-γ and IFN-γ/TGF-β1 licensing enhanced the immunomodulatory effect of MSCs on T cell proliferation. Further, TGF-β1 and IFN-γ licensing strengthened the immunomodulatory effect of MSC on reducing the TNF-α and IL-1β expression by M1 macrophage-like THP-1 cells. Additionally, we discovered the immunomodulatory effect mediated by MSC-derived apoptotic bodies. Licensing impacted the uptake of ABs by recipient immune cells and importantly altered their phenotypes.

CONCLUSION

ABs derived from IFN-γ/TGF-β1-licensed apoptotic MSCs significantly inhibited T cell proliferation, induced more regulatory T cells, and maintained immunomodulatory T cells but reduced pro-inflammatory T cells.

Hypoxia and inflammatory factor preconditioning enhances the immunosuppressive properties of human umbilical cord mesenchymal stem cells

BACKGROUND

Mesenchymal stem cells (MSCs) have great potential for the treatment of various immune diseases due to their unique immunomodulatory properties. However, MSCs exposed to the harsh inflammatory environment of damaged tissue after intravenous transplantation cannot exert their biological effects, and therefore, their therapeutic efficacy is reduced. In this challenging context, an in vitro preconditioning method is necessary for the development of MSC-based therapies with increased immunomodulatory capacity and transplantation efficacy.

AIM

To determine whether hypoxia and inflammatory factor preconditioning increases the immunosuppressive properties of MSCs without affecting their biological characteristics.

METHODS

Umbilical cord MSCs (UC-MSCs) were pretreated with hypoxia (2% O2) exposure and inflammatory factors (interleukin-1β, tumor necrosis factor-α, interferon-γ) for 24 h. Flow cytometry, polymerase chain reaction, enzyme-linked immunosorbent assay and other experimental methods were used to evaluate the biological characteristics of pretreated UC-MSCs and to determine whether pretreatment affected the immunosuppressive ability of UC-MSCs in coculture with immune cells.

RESULTS

Pretreatment with hypoxia and inflammatory factors caused UC-MSCs to be elongated but did not affect their viability, proliferation or size. In addition, pretreatment significantly decreased the expression of coagulation-related tissue factors but did not affect the expression of other surface markers. Similarly, mitochondrial function and integrity were retained. Although pretreatment promoted UC-MSC apoptosis and senescence, it increased the expression of genes and proteins related to immune regulation. Pretreatment increased peripheral blood mononuclear cell and natural killer (NK) cell proliferation rates and inhibited NK cell-induced toxicity to varying degrees.

CONCLUSION

In summary, hypoxia and inflammatory factor preconditioning led to higher immunosuppressive effects of MSCs without damaging their biological characteristics.

sFgl2 gene-modified MSCs regulate the differentiation of CD4+ T cells in the treatment of autoimmune hepatitis

BACKGROUND

Autoimmune hepatitis (AIH) is a T-cell-mediated autoimmune liver disease that can lead to liver injury and has a poor long-term prognosis. Mesenchymal stromal cells (MSCs) have immunosuppressive effects and can treat AIH. CD4+ T cells express the unique inhibitory Fcγ receptor (FcγRIIB), which is the only receptor for the immunosuppressive factor soluble fibrinogen-like protein 2 (sFgl2). This study aimed to examine the therapeutic effect of sFgl2 gene-modified MSCs (sFgl2-MSCs) on AIH.

METHODS

MSCs were obtained from the inguinal fat of mice and cocultured with CD4+ T cells sorted from mouse spleens. FcγRIIB expression on CD4+ T cells was determined by flow cytometry. sFgl2 expression in MSCs transfected with lentiviral vectors carrying the Fgl2 gene and a green fluorescent protein-encoding sequence was determined by enzyme-linked immunosorbent assay. The percentages of Th1 cells Th17 cells and regulatory T cells (Tregs) were determined by flow cytometry And the levels of p-SHP2 and p-SMAD2/3 were detected by Western blotting after the cells were cocultured with MSCs for 72 h. After locating MSCs by in vivo imaging Con A-induced experimental AIH mice were randomly divided into 4 groups and administered different treatments. After 24 h histopathological scores liver function and cytokine levels were examined and the proportions of CD4+ T cells CD8+ T cells Tregs Th17 cells and Th1 cells in the spleen and liver were determined by flow cytometry. In addition immunohistochemical staining was used to detect the liver infiltration of T-bet-, Foxp3- and RORγ-positive cells.

RESULTS

FcγRIIB expression on CD4+ T cells was upregulated after coculture with MSCs. After coculture with sFgl2-MSCs, the proportion of Tregs among CD4+ T cells increased, the proportion of Th17 and Th1 cells decreased, and the levels of p-SHP2 and p-SMAD2/3 increased. In vivo, sFgl2-MSCs significantly improved liver function, decreased liver necrosis area, decreased tumor necrosis factor-α, interleukin (IL)-1β and IL-6 expression, increased IL-10 expression, reduced liver infiltration of CD4+ T and CD8+ T cells, increased the proportion of Tregs and reduced the proportions of Th17 and Th1 cells in mice.

CONCLUSION

By promoting Tregs differentiation and inhibiting Th17 and Th1 cell differentiation, sFgl2 gene-modified MSCs have a more powerful therapeutic effect on Con A-induced experimental AIH and may represent a strategy for the clinical treatment of AIH.

Emerging cellular and immunotherapies for systemic sclerosis: from mesenchymal stromal cells to CAR-T cells and vaccine-based approaches

PURPOSE OF REVIEW

Although two targeted therapies have received recent approval for systemic sclerosis (SSc)-associated interstitial lung disease, they do not show major disease-modifying activity, highlighting the need for novel therapies and innovative paradigms. To that end, cellular therapies may represent a new opportunity for the treatment of SSc. The purpose of this review is to provide an up-to-date overview of emerging cell-based disease-modifying therapies in SSc.

RECENT FINDINGS

Initial small studies in patients with severe refractory systemic lupus erythematosus (SLE) using engineered regulatory cells show promising results. CD19-directed CAR-T have shown promising results in one case report of refractory diffuse cutaneous SSc patients. T cells engineered to express a chimeric autoantibody receptor (CAAR-T cells) may be even more relevant via the specific elimination of auto-reactive B cells. Targeting pro-fibrotic or senescence-related pathways may also constitute promising approaches in SSc.

SUMMARY

Building on the classification of the clinical phenotype and prediction of clinical trajectory based on individual patients' autoantigen and/or autoantibody profile, cellular therapies targeting the same autoantigen or related autoreactive cells may represent an unprecedented opportunity to implement personalized medicine in SSc.

Apoptotic Vesicles of MSCs: The Natural Therapeutic Agents and Bio-Vehicles for Targeting Drug Delivery

Mesenchymal stem cell (MSC)-based therapies are increasingly recognized as promising cellular therapeutics and show the ability to treat various diseases. However, the underlying mechanism is not fully elucidated. Some recent studies have shown an unexpected result whereby MSCs undergo rapid apoptosis following administration but still exert therapeutic effects in some disease treatments. Such a therapeutic mechanism is believed to associate with the released apoptotic vesicles from apoptotic MSCs (MSC-ApoVs). This finding inspires a novel therapeutic strategy for using MSC-ApoVs for disease treatment. The present review aims to summarize the biogenesis, physiological functions, therapeutic potentials, and related mechanisms of apoptotic vesicles in MSC-based therapy. In addition, the potential applications of MSC-ApoVs as natural therapeutic agents and natural drug delivery vehicles are proposed and highlighted. The present review is hoped to provide a general understanding of MSC-ApoVs in disease treatment and inspire potential applications in targeted drug delivery.

Umbilical cord mesenchymal stromal cell-derived extracellular vesicles lack the potency to immunomodulate human monocyte-derived macrophages in vitro

Mesenchymal stromal cells (MSCs) have been reported to display efficacy in a variety of preclinical models, but without long-term engraftment, suggesting a role for secreted factors, such as MSC-derived extracellular vesicles (EVs). MSCs are known to elicit immunomodulatory effects, an important aspect of which is their ability to affect macrophage phenotype. However, it is not clear if these effects are mediated by MSC-derived EVs, or other factors secreted by the MSCs. Here, we use flow cytometry to assess the effects of human umbilical cord (hUC) MSC-derived EVs on the expression of pro-inflammatory (CD80) and anti-inflammatory (CD163) surface markers in human monocyte-derived macrophages (hMDMs). hUC-MSC-derived EVs did not change the surface marker expression of the hMDMs. In contrast, when hMDMs were co-incubated with hUC-MSCs in indirect co-cultures, changes were observed in the expression of CD14, CD80 and CD163, particularly in M1 macrophages, suggesting that soluble factors are necessary to elicit a shift in phenotype. However, even though EVs did not alter the surface marker expression of macrophages, they promoted angiogenesis and phagocytic capacity increased proportionally to increases in EV concentration. Taken together, these results suggest that hUC-MSC-derived EVs are not sufficient to alter macrophage phenotype and that additional MSC-derived factors are needed.

Alveolar epithelial regeneration in the aging lung

Advancing age is the most important risk factor for the development of and mortality from acute and chronic lung diseases, including pneumonia, chronic obstructive pulmonary disease, and pulmonary fibrosis. This risk was manifest during the COVID-19 pandemic, when elderly people were disproportionately affected and died from SARS-CoV-2 pneumonia. However, the recent pandemic also provided lessons on lung resilience. An overwhelming majority of patients with SARS-CoV-2 pneumonia, even those with severe disease, recovered with near-complete restoration of lung architecture and function. These observations are inconsistent with historic views of the lung as a terminally differentiated organ incapable of regeneration. Here, we review emerging hypotheses that explain how the lung repairs itself after injury and why these mechanisms of lung repair fail in some individuals, particularly the elderly.

The role of efferocytosis-fueled macrophage metabolism in the resolution of inflammation

The phagocytosis of dying cells by macrophages, termed efferocytosis, is a tightly regulated process that involves the sensing, binding, engulfment, and digestion of apoptotic cells. Efferocytosis not only prevents tissue necrosis and inflammation caused by secondary necrosis of dying cells, but it also promotes pro-resolving signaling in macrophages, which is essential for tissue resolution and repair following injury or inflammation. An important factor that contributes to this pro-resolving reprogramming is the cargo that is released from apoptotic cells after their engulfment and phagolysosomal digestion by macrophages. The apoptotic cell cargo contains amino acids, nucleotides, fatty acids, and cholesterol that function as metabolites and signaling molecules to bring about this re-programming. Here, we review efferocytosis-induced changes in macrophage metabolism that mediate the pro-resolving functions of macrophages. We also discuss various strategies, challenges, and future perspectives related to drugging efferocytosis-fueled macrophage metabolism as strategy to dampen inflammation and promote resolution in chronic inflammatory diseases.

Sex Hormone-Binding Globulin (SHBG) Maintains Proper Equine Adipose-Derived Stromal Cells (ASCs)' Metabolic Functions and Negatively Regulates their Basal Adipogenic Potential

BACKGROUND

Sex hormone binding globulin (SHBG) deteriorated expression has been recently strongly correlated to increased level of circulating pro-inflammatory cytokines and insulin resistance, which are typical manifestations of equine metabolic syndrome (EMS). Despite previous reports demonstrated the potential therapeutic application of SHBG for liver-related dysfunctions, whether SHBG might modulate equine adipose-derived stem/stromal cells (EqASCs) metabolic machinery remains unknown. Therefore, we evaluated for the first time the impact of SHBG protein on metabolic changes in ASCs isolated from healthy horses.

METHODS

Beforehand, SHBG protein expression has been experimentally lowered using a predesigned siRNA in EqASCs to verify its metabolic implications and potential therapeutic value. Then, apoptosis profile, oxidative stress, mitochondrial network dynamics and basal adipogenic potential have been evaluated using various molecular and analytical techniques.

RESULTS

The SHBG knockdown altered the proliferative and metabolic activity of EqASCs, while dampening basal apoptosis via Bax transcript suppression. Furthermore, the cells treated with siRNA were characterized by senescent phenotype, accumulation of reactive oxygen species (ROS), nitric oxide, as well as decreased mitochondrial potential that was shown by mitochondrial membrane depolarization and lower expression of key mitophagy factors: PINK, PARKIN and MFN. The addition of SHBG protein reversed the impaired and senescent phenotype of EMS-like cells that was proven by enhanced proliferative activity, reduced apoptosis resistance, lower ROS accumulation and greater mitochondrial dynamics, which is proposed to be related to a normalization of Bax expression. Crucially, SHBG silencing enhanced the expression of key pro-adipogenic effectors, while decreased the abundance of anti-adipogenic factors namely HIF1-α and FABP4. The addition of exogenous SHBG further depleted the expression of PPARγ and C/EBPα and restored the levels of FABP4 and HIF1-α evoking a strong inhibitory potential toward ASCs adipogenesis.

CONCLUSION

Herein, we provide for the first time the evidence that SHBG protein in importantly involved in various key metabolic pathways governing EqASCs functions, and more importantly we showed that SHBG negatively affect the basal adipogenic potential of tested ASCs through a FABP4-dependant pathway, and provide thus new insights for the development of potential anti-obesity therapeutic approach in both animals and humans.

Intravenous Administration of Human Umbilical Cord Mesenchymal Stromal Cells Leads to an Inflammatory Response in the Lung

Mesenchymal stromal cells (MSCs) administered intravenously (IV) have shown efficacy in preclinical models of various diseases. This is despite the cells not reaching the site of injury due to entrapment in the lungs. The immunomodulatory properties of MSCs are thought to underlie their therapeutic effects, irrespective of whether they are sourced from bone marrow, adipose tissue, or umbilical cord. To better understand how MSCs affect innate immune cell populations in the lung, we evaluated the distribution and phenotype of neutrophils, monocytes, and macrophages by flow cytometry and histological analyses after delivering human umbilical cord-derived MSCs (hUC-MSCs) IV into immunocompetent mice. After 2 hr, we observed a significant increase in neutrophils, and proinflammatory monocytes and macrophages. Moreover, these immune cells localized in close proximity to the MSCs, suggesting an active role in their clearance. By 24 hr, we detected an increase in anti-inflammatory monocytes and macrophages. These results suggest that the IV injection of hUC-MSCs leads to an initial inflammatory phase in the lung shortly after injection, followed by a resolution phase 24 hr later.

Serum from patients with asthma potentiates macrophage phagocytosis and human mesenchymal stromal cell therapy in experimental allergic asthma

BACKGROUND/AIMS

Although several studies have demonstrated that mesenchymal stromal cells (MSCs) exhibit beneficial immunomodulatory properties in preclinical models of allergic asthma, effects on airway remodeling have been controversial. Recent evidence has shown that MSCs modify their in vivo immunomodulatory actions depending on the specific inflammatory environment encountered. Accordingly, we assessed whether the therapeutic properties of human mesenchymal stromal cells (hMSCs) could be potentiated by conditioning these cells with serum (hMSC-serum) obtained from patients with asthma and then transplanted in an experimental model of house dust mite (HDM)-induced allergic asthma.

METHODS

hMSC and hMSC-serum were administered intratracheally 24 h after the final HDM challenge. hMSC viability and inflammatory mediator production, lung mechanics and histology, bronchoalveolar lavage fluid (BALF) cellularity and biomarker levels, mitochondrial structure and function as well as macrophage polarization and phagocytic capacity were assessed.

RESULTS

Serum preconditioning led to: (i) increased hMSC apoptosis and expression of transforming growth factor-β, interleukin (IL)-10, tumor necrosis factor-α-stimulated gene 6 protein and indoleamine 2,3-dioxygenase-1; (ii) fission and reduction of the intrinsic respiratory capacity of mitochondria; and (iii) polarization of macrophages to M2 phenotype, which may be associated with a greater percentage of hMSCs phagocytosed by macrophages. Compared with mice receiving hMSCs, administration of hMSC-serum led to further reduction of collagen fiber content, eotaxin levels, total and differential cellularity and increased IL-10 levels in BALF, improving lung mechanics. hMSC-serum promoted greater M2 macrophage polarization as well as macrophage phagocytosis, mainly of apoptotic hMSCs.

CONCLUSIONS

Serum from patients with asthma led to a greater percentage of hMSCs phagocytosed by macrophages and triggered immunomodulatory responses, resulting in further reductions in both inflammation and remodeling compared with non-preconditioned hMSCs.

Efficient delivery of mesenchymal stem/stromal cells to injured liver by surface PEGylation

BACKGROUND

Mesenchymal stem/stromal cells (MSCs) have been used in clinical trials for various diseases. These have certain notable functions such as homing to inflammation sites, tissue repair, and immune regulation. In many pre-clinical studies, MSCs administered into peripheral veins demonstrated effective therapeutic outcomes. However, most of the intravenously administered MSCs were entrapped in the lung, and homing to target sites was less than 1%. This occurred mainly because of the adhesion of MSCs to vascular endothelial cells in the lung. To prevent this adhesion, we modified the surface of MSCs with polyethylene glycol (PEG; a biocompatible polymer) using the avidin-biotin complex (ABC) method.

METHODS

The surface of MSCs was modified with PEG using the ABC method. Then, the cell adhesion to mouse aortic endothelial cells and the tissue distribution of PEG-modified MSCs were evaluated. Moreover, the homing to the injured liver and therapeutic effect of PEG-modified MSCs were evaluated using carbon tetrachloride-induced acute liver failure model mice.

RESULTS

The PEG modification significantly suppressed the adhesion of MSCs to cultured mouse aortic endothelial cells as well as the entrapment of MSCs in the lungs after intravenous injection in mice. PEG-modified MSCs efficiently homed to the injured liver of carbon tetrachloride-induced acute liver failure model mice. More importantly, the cells significantly suppressed serum transaminase levels and leukocyte infiltration into the injured liver.

CONCLUSION

These results indicate that PEG modification to the surface of MSCs can suppress the lung entrapment of intravenously administered MSCs and improve their homing to the injured liver.

Efferocytosis of viable versus heat-inactivated MSC induces human monocytes to distinct immunosuppressive phenotypes

BACKGROUND

Immunomodulation by mesenchymal stromal cells (MSCs) can occur through trophic factor mechanisms, however, intravenously infused MSCs are rapidly cleared from the body yet a potent immunotherapeutic response is still observed. Recent work suggests that monocytes contribute to the clearance of MSCs via efferocytosis, the body's natural mechanism for clearing dead and dying cells in a non-inflammatory manner. This begs the questions of how variations in MSC quality affect monocyte phenotype and if viable MSCs are even needed to elicit an immunosuppressive response.

METHODS

Herein, we sought to dissect MSC's trophic mechanism from their efferocytic mechanisms and determine if the viability of MSCs prior to efferocytosis influences the resultant phenotype of monocytes. We cultured viable or heat-inactivated human umbilical cord MSCs with human peripheral blood mononuclear cells for 24 h and observed changes in monocyte surface marker expression and secretion profile. To isolate the effect of efferocytosis from MSC trophic factors, we used cell separation techniques to remove non-efferocytosed MSCs before challenging monocytes to suppress T-cells or respond to inflammatory stimuli. For all experiments, viable and heat-inactivated efferocytic-licensing of monocytes were compared to non-efferocytic-licensing control.

RESULTS

We found that monocytes efferocytose viable and heat-inactivated MSCs equally, but only viable MSC-licensed monocytes suppress activated T-cells and suppression occurred even after depletion of residual MSCs. This provides direct evidence that monocytes that efferocytose viable MSCs are immunosuppressive. Further characterization of monocytes after efferocytosis showed that uptake of viable-but not heat inactivated-MSC resulted in monocytes secreting IL-10 and producing kynurenine. When monocytes were challenged with LPS, IL-2, and IFN-γ to simulate sepsis, monocytes that had efferocytosed viable MSC had higher levels of IDO while monocytes that efferocytosed heat inactivated-MSCs produced the lowest levels of TNF-α.

CONCLUSION

Collectively, these studies show that the quality of MSCs efferocytosed by monocytes polarize monocytes toward distinctive immunosuppressive phenotypes and highlights the need to tailor MSC therapies for specific indications.

Mesenchymal Stem Cell-Derived Extracellular Vesicles: An Emerging Diagnostic and Therapeutic Biomolecules for Neurodegenerative Disabilities

Mesenchymal stem cells (MSCs) are a type of versatile adult stem cells present in various organs. These cells give rise to extracellular vesicles (EVs) containing a diverse array of biologically active elements, making them a promising approach for therapeutics and diagnostics. This article examines the potential therapeutic applications of MSC-derived EVs in addressing neurodegenerative disorders such as Alzheimer's disease (AD), multiple sclerosis (MS), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and Huntington's disease (HD). Furthermore, the present state-of-the-art for MSC-EV-based therapy in AD, HD, PD, ALS, and MS is discussed. Significant progress has been made in understanding the etiology and potential treatments for a range of neurodegenerative diseases (NDs) over the last few decades. The contents of EVs are carried across cells for intercellular contact, which often results in the control of the recipient cell's homeostasis. Since EVs represent the therapeutically beneficial cargo of parent cells and are devoid of many ethical problems connected with cell-based treatments, they offer a viable cell-free therapy alternative for tissue regeneration and repair. Developing innovative EV-dependent medicines has proven difficult due to the lack of standardized procedures in EV extraction processes as well as their pharmacological characteristics and mechanisms of action. However, recent biotechnology and engineering research has greatly enhanced the content and applicability of MSC-EVs.

Therapeutic effects of different intervention forms of human umbilical cord mesenchymal stem cells in the treatment of osteoarthritis

Osteoarthritis (OA) is a common and disabling disease. For advanced OA, surgical treatment is still the main treatment. Human umbilical cord mesenchymal stem cells (hUC-MSCs) are self-regenerative pluripotent cells, that coordinate cartilage regeneration by secreting various trophic factors, which adjust the injured tissue environment. hUC-MSCs secret extracellular vesicles and participates in OA treatment by transmitting bioactive molecules related to migration, proliferation, apoptosis, inflammatory reaction, extracellular matrix synthesis and cartilage repair. In addition, the combination of multiple substances represented by cartilage matrix and hUC-MSCs also have a significant synergistic effect on OA treatment. Because hUC-MSCs have shown considerable promise in cartilage repair, some scholars have proposed transplanting mesenchymal stem cells into damaged cartilage to delay OA progression. This article reviews the application of hUC-MSCs as a treatment for OA. With the continuous development of routine clinical applications, more reliable intervention modalities for hUC-MSCs in OA treatment will be discovered for the time to come.

Comparison of immunotherapy mediated by apoptotic bodies, microvesicles and exosomes: apoptotic bodies' unique anti-inflammatory potential

Immunotherapy, including immunostimulation and immunosuppression, has seen significant development in the last 10 years. Immunostimulation has been verified as effective in anti-cancer treatment, while immunosuppression is used in the treatment of autoimmune disease and inflammation. Currently, with the update of newly-invented simplified isolation methods and the findings of potent triggered immune responses, extracellular vesicle-based immunotherapy is very eye-catching. However, the research on three main types of extracellular vesicles, exosomes, microvesicles and apoptotic bodies, needs to be more balanced. These three subtypes share a certain level of similarity, and at the same time, they have their own properties caused by the different methods of biogensis. Herein, we summarized respectively the status of immunotherapy based on each kind of vesicle and discuss the possible involved mechanisms. In conclusion, we highlighted that the effect of the apoptotic body is clear and strong. Apoptotic bodies have an excellent potential in immunosuppressive and anti-inflammatory therapies .

Mesenchymal condensation in tooth development and regeneration: a focus on translational aspects of organogenesis

The teeth are vertebrate-specific, highly specialized organs performing fundamental functions of mastication and speech, the maintenance of which is crucial for orofacial homeostasis and is further linked to systemic health and human psychosocial well-being. However, with limited ability for self-repair, the teeth can often be impaired by traumatic, inflammatory, and progressive insults, leading to high prevalence of tooth loss and defects worldwide. Regenerative medicine holds the promise to achieve physiological restoration of lost or damaged organs, and in particular an evolving framework of developmental engineering has pioneered functional tooth regeneration by harnessing the odontogenic program. As a key event of tooth morphogenesis, mesenchymal condensation dictates dental tissue formation and patterning through cellular self-organization and signaling interaction with the epithelium, which provides a representative to decipher organogenetic mechanisms and can be leveraged for regenerative purposes. In this review, we summarize how mesenchymal condensation spatiotemporally assembles from dental stem cells (DSCs) and sequentially mediates tooth development. We highlight condensation-mimetic engineering efforts and mechanisms based on ex vivo aggregation of DSCs, which have achieved functionally robust and physiologically relevant tooth regeneration after implantation in animals and in humans. The discussion of this aspect will add to the knowledge of development-inspired tissue engineering strategies and will offer benefits to propel clinical organ regeneration.

Scale-Up of Academic Mesenchymal Stromal Cell Production

BACKGROUND

Many clinical trials have reported the use of mesenchymal stromal cells (MSCs) following the indication of severe SARS-CoV-2 infection. However, in the COVID19 pandemic context, academic laboratories had to adapt a production process to obtain MSCs in a very short time. Production processes, especially freezing/thawing cycles, or culture medium have impacts on MSC properties. We evaluated the impact of an intermediate cryopreservation state during MSC culture to increase production yields.

METHODS

Seven Wharton's jelly (WJ)-MSC batches generated from seven different umbilical cords with only one cryopreservation step and 13 WJ-MSC batches produced with intermediate freezing were formed according to good manufacturing practices. The identity (phenotype and clonogenic capacities), safety (karyotype, telomerase activity, sterility, and donor qualification), and functionality (viability, mixed lymphocyte reaction) were analyzed.

RESULTS

No significant differences between MSC production processes were observed, except for the clonogenic capacity, which was decreased, although it always remained above our specifications.

CONCLUSIONS

Intermediate cryopreservation allows an increase in the production yield and has little impact on the basic characteristics of MSCs.