Modulating the distribution and fate of exogenously delivered MSCs to enhance therapeutic potential: knowns and unknowns

hAMSCs regulate EMT in the progression of experimental pulmonary fibrosis through delivering miR-181a-5p targeting TGFBR1

BACKGROUND

Pulmonary fibrosis (PF) is a common and multidimensional devastating interstitial lung disease. The development of novel and more effective interventions for PF is an urgent clinical need. A previous study has found that miR-181a-5p plays an important role in the development of PF, and human amniotic mesenchymal stem cells (hAMSCs) exert potent therapeutic potential on PF. However, whether hAMSCs act on PF by delivering miR-181a-5p and its detailed mechanism still remain unknown. Thus, this study was designed to investigate the underlying possible mechanism of hAMSCs on PF in bleomycin (BLM)-induced mouse PF model, and a co-culture system of hAMSCs and A549 cells epithelial mesenchymal transition (EMT) model, focusing on its effects on collagen deposition, EMT, and epithelial cell cycle regulation.

METHODS

hAMSCs with different miR-181a-5p expression levels were constructed. BLM (4 mg/kg) was used to create a PF model, while TGF-β1 was used to induce A549 cells to construct an EMT model. Furthermore, the effects of different miR-181a-5p expression in hAMSCs on collagen deposition and EMT during lung fibrosis were assessed in vivo and in vitro.

RESULTS

We found that hAMSCs exerted anti-fibrotic effect in BLM-induced mouse PF model. Moreover, hAMSCs also exerted protective effect on TGFβ1-induced A549 cell EMT model. Furthermore, hAMSCs ameliorated PF by promoting epithelial cell proliferation, reducing epithelial cell apoptosis, and attenuating EMT of epithelial cells through paracrine effects. hAMSCs regulated EMT in PF through delivering miR-181a-5p targeting TGFBR1.

CONCLUSIONS

Our findings reveal for the first time that hAMSCs inhibit PF by promoting epithelial cell proliferation, reducing epithelial cell apoptosis, and attenuating EMT. Mechanistically, the therapeutic effect of hMASCs on PF is achieved through delivering miR-181a-5p targeting TGFBR1.

Umbilical cord-derived mesenchymal stem cells preferentially modulate macrophages to alleviate pulmonary fibrosis

BACKGROUND

Idiopathic Pulmonary Fibrosis (IPF) is a type of interstitial lung disease characterized by chronic inflammation due to persistent lung damage. Mesenchymal stem cells (MSCs), including those derived from the umbilical cord (UCMSCs) and placenta (PLMSCs), have been utilized in clinical trials for IPF treatment. However, the varying therapeutic effectiveness between these two MSC types remains unclear.

METHODS

In this study, we examined the therapeutic differences between UCMSCs and PLMSCs in treating lung damage using a bleomycin (BLM)-induced pulmonary injury mouse model.

RESULTS

We showed that UCMSCs had a superior therapeutic impact on lung damage compared to PLMSCs. Upon cytokine stimulation, UCMSCs expressed higher levels of inflammation-related genes and more effectively directed macrophage polarization towards the M2 phenotype than PLMSCs, both in vitro and in vivo. Furthermore, UCMSCs showed a preference for expressing CC motif ligation 2 (CCL2) and C-X-C motif chemokine ligand 1 (CXCL1) compared to PLMSCs. The expression of secreted phosphoprotein 1 (SPP1), triggering receptor expressed on myeloid cells 2 (Trem2), and CCAAT enhancer binding protein beta (Cebpb) in macrophages from mice with the disease treated with UCMSCs was significantly reduced compared to those treated with PLMSCs.

CONCLUSIONS

Therefore, UCMSCs demonstrated superior anti-fibrotic abilities in treating lung damage, potentially through inducing a more robust M2 polarization of macrophages than PLMSCs.

Impact of mesenchymal stem cell size and adhesion modulation on in vivo distribution: insights from quantitative PET imaging

BACKGROUND

Successful engraftment and localization of mesenchymal stem cells (MSCs) within target tissues are critical factors influencing their therapeutic efficacy for tissue repair and regeneration. However, the relative contributions of biophysical factors like cell size and adhesion capacity in regulating MSC distribution in vivo remain incompletely understood.

METHODS

Cell adhesion peptides and hanging drop method were used to modify the adhesive capacity and size of MSCs. To quantitatively track the real-time biodistribution of transplanted MSCs with defined size and adhesion profiles in living mice and rats, the non-invasive positron emission tomography (PET) imaging was applied.

RESULTS

Surface modification with integrin binding peptides like RGD, GFOGER, and HAVDI reduced MSC adhesion capacity in vitro by up to 43.5% without altering cell size, but did not significantly decrease lung entrapment in vivo. In contrast, culturing MSCs as 3D spheroids for 48 h reduced their cell diameter by 34.6% and markedly enhanced their ability to pass through the lungs and migrate to other organs like the liver after intravenous administration. This size-dependent effect on MSC distribution was more pronounced in rats compared to mice, likely due to differences in pulmonary microvessel diameters between species.

CONCLUSION

Our findings reveal that cell size is a predominant biophysical regulator of MSC localization in vivo compared to adhesion capacity, providing crucial insights to guide optimization of MSC delivery strategies for enhanced therapeutic efficacy.

Renal remodeling by CXCL10-CXCR3 axis-recruited mesenchymal stem cells and subsequent IL4I1 secretion in lupus nephritis

Human umbilical cord mesenchymal stem cells (hUC-MSCs) have shown potential as a therapeutic option for lupus nephritis (LN), particularly in patients refractory to conventional treatments. Despite extensive translational research on MSCs, the precise mechanisms by which MSCs migrate to the kidney and restore renal function remain incompletely understood. Here, we aim to clarify the spatiotemporal characteristics of hUC-MSC migration into LN kidneys and their interactions with host cells in microenvironment. This study elucidates that the migration of hUC-MSCs to the LN kidney is driven by elevated levels of CXCL10, predominantly produced by glomerular vascular endothelial cells through the IFN-γ/IRF1-KPNA4 pathway. Interestingly, the blockade of CXCL10-CXCR3 axis impedes the migration of hUC-MSCs to LN kidney and negatively impacts therapeutic outcomes. Single cell-RNA sequencing analysis underscores the importance of this axis in mediating the regulatory effects of hUC-MSCs on the renal immune environment. Furthermore, hUC-MSCs have been observed to induce and secrete interleukin 4 inducible gene 1 (IL4I1) in response to the microenvironment of LN kidney, thereby suppressing Th1 cells. Genetically ablating IL4I1 in hUC-MSCs abolishes their therapeutic effects and prevents the inhibition of CXCR3+ Th1 cell infiltration into LN kidneys. This study provides valuable insights into the significant involvement of CXCL10-CXCR3 axis in hUC-MSC migration to the LN kidneys and the subsequent remodeling of renal immune microenvironment. Regulating the CXCL10-CXCR3 axis and IL4I1 secretion may be developed as a novel therapeutic strategy to improve treatment outcomes of LN.

The MSC-EV-microRNAome: A Perspective on Therapeutic Mechanisms of Action in Sepsis and ARDS

Mesenchymal stromal cells (MSCs) and MSC-derived extracellular vesicles (EVs) have emerged as innovative therapeutic agents for the treatment of sepsis and acute respiratory distress syndrome (ARDS). Although their potential remains undisputed in pre-clinical models, this has yet to be translated to the clinic. In this review, we focused on the role of microRNAs contained in MSC-derived EVs, the EV microRNAome, and their potential contribution to therapeutic mechanisms of action. The evidence that miRNA transfer in MSC-derived EVs has a role in the overall therapeutic effects is compelling. However, several questions remain regarding how to reconcile the stochiometric issue of the low copy numbers of the miRNAs present in the EV particles, how different miRNAs delivered simultaneously interact with their targets within recipient cells, and the best miRNA or combination of miRNAs to use as therapy, potency markers, and biomarkers of efficacy in the clinic. Here, we offer a molecular genetics and systems biology perspective on the function of EV microRNAs, their contribution to mechanisms of action, and their therapeutic potential.

Hematopoietic Endothelial Progenitor cells enhance motor function and cortical motor map integrity following cerebral ischemia

Background

Hematopoietic stem cells (HSC) are recruited to ischemic areas in the brain and contribute to improved functional outcome in animals. However, little is known regarding the mechanisms of improvement following HSC administration post cerebral ischemia. To better understand how HSC effect post-stroke improvement, we examined the effect of HSC in ameliorating motor impairment and cortical dysfunction following cerebral ischemia.

Methods

Baseline motor performance of male adult rats was established on validated motor tests. Animals were assigned to one of three experimental cohorts: control, stroke, stroke + HSC. One, three and five weeks following a unilateral stroke all animals were tested on motor skills after which intracortical microstimulation was used to derive maps of forelimb movement representations within the motor cortex ipsilateral to the ischemic injury.

Results

Stroke + HSC animals significantly outperformed stroke animals on single pellet reaching at weeks 3 and 5 (28±3% and 33±3% versus 11±4% and 17±3%, respectively, p < 0.05 at both time points). Control animals scored 44±1% and 47±1%, respectively. Sunflower seed opening task was significantly improved in the stroke + HSC cohort versus the stroke cohort at week five-post stroke (79±4 and 48±5, respectively, p < 0.05). Furthermore, Stroke + HSC animals had significantly larger forelimb motor maps than animals in the stroke cohort. Overall infarct size did not significantly differ between the two stroked cohorts.

Conclusion

These data suggest that post stroke treatment of HSC enhances the functional integrity of residual cortical tissue, which in turn supports improved behavioral outcome, despite no observed reduction in infarct size.

Mesenchymal Stem Cell-Based Therapies in the Post-Acute Neurological COVID Syndrome: Current Landscape and Opportunities

One of the main concerns related to SARS-CoV-2 infection is the symptoms that could be developed by survivors, known as long COVID, a syndrome characterized by persistent symptoms beyond the acute phase of the infection. This syndrome has emerged as a complex and debilitating condition with a diverse range of manifestations affecting multiple organ systems. It is increasingly recognized for affecting the Central Nervous System, in which one of the most prevalent manifestations is cognitive impairment. The search for effective therapeutic interventions has led to growing interest in Mesenchymal Stem Cell (MSC)-based therapies due to their immunomodulatory, anti-inflammatory, and tissue regenerative properties. This review provides a comprehensive analysis of the current understanding and potential applications of MSC-based interventions in the context of post-acute neurological COVID-19 syndrome, exploring the underlying mechanisms by which MSCs exert their effects on neuroinflammation, neuroprotection, and neural tissue repair. Moreover, we discuss the challenges and considerations specific to employing MSC-based therapies, including optimal delivery methods, and functional treatment enhancements.

Mesenchymal Stromal Cell Therapy for Thoracic Surgeons: An Update

Stem cells are undifferentiated cells presenting extensive self-renewal features and the ability to differentiate "in vitro" and "in vivo" into a range of lineage cells, like chondrogenic, osteogenic and adipogenic lineages when cultured in specific inducing media. Two major domains of clinical applications of stem cells in thoracic surgery have been investigated: regenerative medicine, which is a section of translational research in tissue engineering focusing on the replacement, renewal or regeneration of cells, tissues and organs to re-establish damaged physiologic functions; drug loading and delivery, representing a new branch proposing stem cells as carriers to provide selected districts with anti-cancer agents for targeted treatments.

Complementary early-phase magnetic particle imaging and late-phase positron emission tomography reporter imaging of mesenchymal stem cells in vivo

Stem cell-based therapies have demonstrated significant potential in clinical applications for many debilitating diseases. The ability to non-invasively and dynamically track the location and viability of stem cells post administration could provide important information on individual patient response and/or side effects. Multi-modal cell tracking provides complementary information that can offset the limitations of a single imaging modality to yield a more comprehensive picture of cell fate. In this study, mesenchymal stem cells (MSCs) were engineered to express human sodium iodide symporter (NIS), a clinically relevant positron emission tomography (PET) reporter gene, as well as labeled with superparamagnetic iron oxide nanoparticles (SPIOs) to allow for detection with magnetic particle imaging (MPI). MSCs were additionally engineered with a preclinical bioluminescence imaging (BLI) reporter gene for comparison of BLI cell viability data to both MPI and PET data over time. MSCs were implanted into the hind limbs of immunocompromised mice and imaging with MPI, BLI and PET was performed over a 30-day period. MPI showed sensitive detection that steadily declined over the 30-day period, while BLI showed initial decreases followed by later rapid increases in signal. The PET signal of MSCs was significantly higher than the background at later timepoints. Early-phase imaging (day 0-9 post MSC injections) showed correlation between MPI and BLI data (R² = 0.671), while PET and BLI showed strong correlation for late-phase (day 10-30 post MSC injections) imaging timepoints (R² = 0.9817). We report the first use of combined MPI and PET for cell tracking and show the complementary benefits of MPI for sensitive detection of MSCs early after implantation and PET for longer-term measurements of cell viability.

Time course and mechanistic analysis of human umbilical cord perivascular cell mitigation of lipopolysaccharide-induced systemic and neurological inflammation

BACKGROUND AIMS

Because of their potent immunomodulatory and anti-inflammatory properties, mesenchymal stromal cells are a major focus in the field of stem cell therapy. However, the precise mechanisms underlying this are not entirely understood. Human umbilical cord perivascular cells (HUCPVCs) are a promising cell therapy candidate. This study was designed to evaluate the time course and mechanisms by which HUCPVCs mitigate lipopolysaccharide (LPS)-induced systemic and neurological inflammation in immunocompetent mice. To explore the underlying mechanisms, the authors investigated the biodistribution and fate of HUCPVCs.

METHODS

Male C57BL/6 mice were randomly allocated to four groups: control, LPS, HUCPVCs or LPS + HUCPVCs. Quantitative polymerase chain reaction, enzyme-linked immunosorbent assay and cytokine arrays were used to assess changes in pro-inflammatory mediators systemically and in the brain. Depressive-like behavioral changes were evaluated via a forced swim test. Quantum dot (qDot) labeling and immunohistochemistry were used to assess the biodistribution and fate of HUCPVCs and interactions with recipient innate immune cells.

RESULTS

A single intravenously delivered dose of HUCPVCs significantly reduced the systemic inflammation induced by LPS within the first 24 h after administration. HUCPVC treatment abrogated the upregulated expression of pro-inflammatory genes in the hippocampus and cortex and attenuated depressive-like behavior induced by LPS treatment. Biodistribution analysis revealed that HUCPVC-derived qDots rapidly accumulated in the lungs and demonstrated limited in vivo persistence. Furthermore, qDot signals were associated with major recipient innate immune cells and promoted a shift in macrophages toward a regulatory phenotype in the lungs.

CONCLUSIONS

Overall, this study demonstrates that HUCPVCs can successfully reduce systemic and neurological inflammation induced by LPS within the first 24 h after administration. Biodistribution and fate analyses suggest a critical role for the innate immune system in the HUCPVC-based immunomodulation mechanism.

T Cell and Cytokine Dynamics in the Blood of Patients after Hematopoietic Stem Cell Transplantation and Multipotent Mesenchymal Stromal Cell Administration

Multipotent mesenchymal stromal cells (MSCs) are currently under intensive investigation for the treatment and prevention of graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (allo-HSCT), owing to their substantial immunomodulatory properties. The responses of recipients to MSC infusion following allo-HSCT are not yet well understood. T cells are central to the adaptive immune system, protecting the organism from infection and malignant cells. Memory T cells with different phenotypes, gene expression profiles, and functional properties are critical for immune processes regulation. The aim of this study was to study the dynamics of memory T cell subpopulations and cytokines in the blood of allo-HSCT recipients after MSC administration. In clinical trial NCT01941394, patients after allo-HSCT were randomized into 2 groups, one receiving standard GVHD prophylaxis and the other also receiving MSC infusion on the day of leukocyte recovery to 1000 cells/μL (engraftment, day E0). Blood samples of patients from both groups were analyzed on days E0, E+3, and E+30. T cell subpopulations were studied by flow cytometry, and cytokine concentrations were evaluated by the Bio-Plex Pro Human Cytokine Panel. Administration of MSCs to patients on day E0 did not affect the overall dynamics of restoration of absolute numbers and proportions of T and B lymphocytes after 3 and 30 days. At 3 days after MSC injection, only the numbers of CD8⁺ effector cells (CD8⁺_TE, CD8⁺_TM, and CD8⁺_EM) were found to increase significantly. A significant increase in the number of CD4⁺ cells after 30 days compared to day E0 was observed only in patients who received MSCs, indicating faster recovery of the CD4⁺ cell population following MSC injection. An increase in CD8⁺ cell number by day E+30 was significant regardless of MSC administration. To characterize the immune status of patients following allo-HSCT in more detail, changes in the cytokine concentration in the peripheral blood of patients on days E0, E+3, and E+30 after MSC administration were investigated. On day E+30, significant increases in the numbers of CD4⁺_CM and activated CD4⁺CD25⁺ cells were observed. The concentrations of proinflammatory and anti-inflammatory cytokines IL-6, IL-8, IL-17, TNF-α, and IFN-γ were increased significantly in patients injected with MSCs. Analysis of growth factor levels showed that in the group of patients who received MSCs, the concentrations of G-CSF, GM-CSF, PDGFbb, FGFb, and IL-5 increased by day E+30. Among the cytokines involved in regulation of the immune response, concentrations of IL-9, eotaxin, IP-10, MCP-1, and MIP-1a were increased after 30 days irrespective of MSC administration. The administration of MSCs exerts a positive effect on the restoration of T cell subpopulations and immune system recovery in patients after allo-HSCT.

Systematic review and meta-analysis of mesenchymal stromal/stem cells as strategical means for the treatment of COVID-19

BACKGROUND

In coronavirus disease 2019 (COVID-19) patients, elevated levels of inflammatory cytokines from over stimulation of immune cells have become a concern due to the potential outburst of cytokine storm that damages the tissues and organs, especially the lungs. This leads to the manifestation of COVID-19 symptoms, such as pneumonia, acute respiratory distress syndrome (ARDS), multiple organ failure, and eventually death. Mesenchymal stromal/stem cells (MSCs) are currently one of hopeful approaches in treating COVID-19 considering its anti-inflammatory and immunomodulatory functions. On that account, the number of clinical trials concerning the use of MSCs for COVID-19 has been increasing. However, the number of systematic reviews and meta-analysis that specifically discuss its potential as treatment for the disease is still lacking. Therefore, this review will assess the safety and efficacy of MSC administration in COVID-19 patients.

OBJECTIVES

To pool evidence on the safety and efficacy of MSCs in treating COVID-19 by observing MSC-related adverse effects as well as evaluating its effects in reducing inflammatory response and improving pulmonary function.

DATA SOURCES AND METHODS

Following literature search across six databases and one trial register, full-text retrieval, and screening against eligibility criteria, only eight studies were included for data extraction. All eight studies evaluated the use of umbilical cord-derived mesenchymal stromal/stem cell (UC-MSC), infused intravenously. Of these eight studies, six studies were included in meta-analysis on the incidence of mortality, adverse events (AEs), and serious adverse events (SAEs), and the levels of C-reactive protein (CRP) and interleukin (IL)-6. Meta-analysis on pulmonary function was not performed due to insufficient data.

RESULTS

MSC-treated group showed significantly lower risk of mortality than the control group (p = 0.03). No statistical significance was observed on the incidence of AEs (p = 0.78) and SAEs (p = 0.44), and the levels of CRP (p = 0.06) and IL-6 (p = 0.09).

CONCLUSION

MSCs were safe for use, with lower risk of mortality and no association with AEs. Regarding efficacy, descriptive analysis showed indications of improvement on the inflammatory reaction, lung clearance, and oxygenation status despite the lack of statistical significance in meta-analysis of CRP and IL-6. Nevertheless, more studies are needed for affirmation.

REGISTRATION

This systematic review and meta-analysis was registered on the PROSPERO database (no. CRD42022307730).

Can a Large Number of Transplanted Mesenchymal Stem Cells Have an Optimal Therapeutic Effect on Improving Ovarian Function?

Mesenchymal stem cells (MSCs) are next-generation treatment in degenerative diseases. For the application of mesenchymal stem cell therapy to degenerative disease, transplantation conditions (e.g., optimized dose, delivery route and regenerating efficacy) should be considered. Recently, researchers have studied the mode of action of MSC in the treatment of ovarian degenerative disease. However, the evidence for the optimal number of cells for the developing stem cell therapeutics is insufficient. The objective of this study was to evaluate the efficacy in ovarian dysfunction, depends on cell dose. By intraovarian transplantation of low (1 × 105) and high (5 × 105) doses of placenta-derived mesenchymal stem cells (PD-MSCs) into thioacetamide (TAA)-injured rats, we compared the levels of apoptosis and oxidative stress that depend on different cell doses. Apoptosis and oxidative stress were significantly decreased in the transplanted (Tx) group compared to the non-transplanted (NTx) group in ovarian tissues from TAA-injured rats (* p < 0.05). In addition, we confirmed that follicular development was significantly increased in the Tx groups compared to the NTx group (* p < 0.05). However, there were no significant differences in the apoptosis, antioxidant or follicular development of injured ovarian tissues between the low and high doses PD-MSCs group. These findings provide new insights into the understanding and evidence obtained from clinical trials for stem cell therapy in reproductive systems.

Dissemination of Multipotent Stromal Cells in the Organism after Their Injection into Intact and Resected Liver in the Experiment

The possibility of dissemination of bone marrow multipotent stromal cells stained with Vybrant CM-Dil after injection into an intact and resected liver was studied using luminescence microscopy. Labeled cells were found in the kidneys, spleen, lungs, axillary, mesenteric, and inguinal lymph nodes. We observed dissemination of multipotent stromal cells and their detritus throughout the body that occurred only after filtration in the lungs, where most cells underwent destruction. Perivascularly located macrophages in various organs can phagocytize multipotent stromal cells and their detritus from blood vessels. The content of objects labeled with Vybrant CM-Dil in distant organs was significantly lower after multipotent stromal cell injection into the resected liver, which was associated with the deposition of cells in the damaged area of the organ and their partial entry into the abdominal cavity.

The Impairment of Blood-Brain Barrier in Alzheimer's Disease: Challenges and Opportunities with Stem Cells

Alzheimer’s disease (AD) is the most common neurodegenerative disorder and its prevalence is increasing. Nowadays, very few drugs effectively reduce AD symptoms and thus, a better understanding of its pathophysiology is vital to design new effective schemes. Presymptomatic neuronal damage caused by the accumulation of Amyloid β peptide and Tau protein abnormalities remains a challenge, despite recent efforts in drug development. Importantly, therapeutic targets, biomarkers, and diagnostic techniques have emerged to detect and treat AD. Of note, the compromised blood-brain barrier (BBB) and peripheral inflammation in AD are becoming more evident, being harmful factors that contribute to the development of the disease. Perspectives from different pre-clinical and clinical studies link peripheral inflammation with the onset and progression of AD. This review aims to analyze the main factors and the contribution of impaired BBB in AD development. Additionally, we describe the potential therapeutic strategies using stem cells for AD treatment.

Microglia-derived CCL2 has a prime role in neocortex neuroinflammation

Background

In myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE), several areas of demyelination are detectable in mouse cerebral cortex, where neuroinflammation events are associated with scarce inflammatory infiltrates and blood–brain barrier (BBB) impairment. In this condition, the administration of mesenchymal stem cells (MSCs) controls neuroinflammation, attenuating astrogliosis and promoting the acquisition of stem cell traits by astrocytes. To contribute to the understanding of the mechanisms involved in the pathogenesis of EAE in gray matter and in the reverting effects of MSC treatment, the neocortex of EAE-affected mice was investigated by analyzing the cellular source(s) of chemokine CCL2, a molecule involved in immune cell recruitment and BBB-microvessel leakage.

Methods

The study was carried out by immunohistochemistry (IHC) and dual RNAscope IHC/in situ hybridization methods, using astrocyte, NG2-glia, macrophage/microglia, and microglia elective markers combined with CCL2.

Results

The results showed that in EAE-affected mice, hypertrophic microglia are the primary source of CCL2, surround the cortex neurons and the damaged BBB microvessels. In EAE-affected mice treated with MSCs, microgliosis appeared diminished very soon (6 h) after treatment, an observation that was long-lasting (tested after 10 days). This was associated with a reduced CCL2 expression and with apparently preserved/restored BBB features. In conclusion, the hallmark of EAE in the mouse neocortex is a condition of microgliosis characterized by high levels of CCL2 expression.

Conclusions

This finding supports relevant pathogenetic and clinical aspects of the human disease, while the demonstrated early control of neuroinflammation and BBB permeability exerted by treatment with MSCs may have important therapeutic implications.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12987-022-00365-5.

Reproductive and Developmental Toxicity Assessment of Human Umbilical Cord Mesenchymal Stem Cells in Rats

Objective: Human umbilical cord mesenchymal stem cells (hUC-MSCs) have shown very attractive potential in clinical applications for the treatment of various diseases. However, the data about the reproductive and developmental toxicity of hUC-MSCs remains insufficient. Thus, we assessed the potential effects of intravenous injection of hUC-MSCs on reproduction and development in Sprague-Dawley rats. Methods: In the fertility and early embryonic development study, hUC-MSCs were administered at dose levels of 0, 6.0 × 106, 8.5 × 106, and 1.2 × 107/kg to male and female rats during the pre-mating, mating and gestation period. In the embryo-fetal development study, the pregnant female rats received 0, 6.0 × 106, 1.2 × 107, and 2.4 × 107/kg of hUC-MSCs from gestation days (GD) 6-15. Assessments made included mortality, clinical observations, body weight, food consumption, fertility parameters of male and female, litter, and fetus parameters, etc. Results: No hUC-MSCs-related toxicity was observed on the fertility of male and female rats, and no teratogenic effect on fetuses. hUC-MSCs at 1.2 × 107/kg caused a mildly decrease in body weight gain of male rats, transient listlessness, tachypnea, and hematuria symptoms in pregnant female rats. Death was observed in part of the pregnant females at a dose of 2.4 × 107/kg, which could be due to pulmonary embolism. Conclusion: Based on the results of the studies, the no-observed-adverse-effect levels (NOAELs) are 8.5 × 106/kg for fertility and early embryonic development, 1.2 × 107/kg for maternal toxicity and 2.4 × 107/kg for embryo-fetal development in rats intravenous injected with hUC-MSCs, which are equivalent to 8.5-fold, 12-fold, and 24-fold respectively of its clinical dosage in humans. These findings may provide a rational basis for human health risk assessment of hUC-MSCs.

Efficacy and Safety of Human Bone Marrow-Derived Mesenchymal Stem Cells according to Injection Route and Dose in a Chronic Kidney Disease Rat Model

Background and Objectives

We compared the efficacy and safety of human bone marrow-derived mesenchymal stem cells (hBMSC), delivered at different doses and via different injection routes in an animal model of chronic kidney disease.

Methods and Results

A total of ninety 12-week-old rats underwent 5/6 nephrectomy and randomized among nine groups: sham, renal artery control (RA-C), tail vein control (TV-C), renal artery low dose (RA-LD) (0.5×10⁶ cells), renal artery moderate dose (RA-MD) (1.0×10⁶ cells), renal artery high dose (RA-HD) (2.0×10⁶ cells), tail vein low dose (TV-LD) (0.5×10⁶ cells), tail vein moderate dose (TV-MD) (1.0×10⁶ cells), and tail vein high dose (TV-HD) (2.0×10⁶ cells). Renal function and mortality of rats were evaluated after hBMSC injection. Serum blood urea nitrogen was significantly lower in the TV-HD group at 2 weeks (p<0.01), 16 weeks (p<0.05), and 24 weeks (p<0.01) than in the TV-C group, as determined by one-way ANOVA. Serum creatinine was significantly lower in the TV-HD group at 24 weeks (p<0.05). At 8 weeks, creatinine clearance was significantly higher in the TV-MD and TV-HD groups (p<0.01, p<0.05) than in the TV-C group. In the safety evaluation, we observed no significant difference among the groups.

Conclusions

Our findings confirm the efficacy and safety of high dose (2×10⁶ cells) injection of hBMSC via the tail vein.

Mesenchymal Stem Cell-Based COVID-19 Therapy: Bioengineering Perspectives

The novel pathogenic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19). Mesenchymal stem cells (MSCs) are currently utilized in clinics for pulmonary inflammatory diseases, including acute respiratory distress syndrome and acute lung injury. Given that MSCs offer a promising treatment against COVID-19, they are being used against COVID-19 in more than 70 clinical trials with promising findings. Genetically engineered MSCs offer promising therapeutic options in pulmonary diseases. However, their potential has not been explored yet. In this review, we provide perspectives on the functionally modified MSCs that can be developed and harnessed for COVID-19 therapy. Options to manage the SARS-CoV-2 infection and its variants using various bioengineering tools to increase the therapeutic efficacy of MSCs are highlighted.

Mesenchymal stem/stromal cell-based therapies for severe viral pneumonia: therapeutic potential and challenges

Severe viral pneumonia is a significant cause of morbidity and mortality globally, whether due to outbreaks of endemic viruses, periodic viral epidemics, or the rarer but devastating global viral pandemics. While limited anti-viral therapies exist, there is a paucity of direct therapies to directly attenuate viral pneumonia-induced lung injury, and management therefore remains largely supportive. Mesenchymal stromal/stem cells (MSCs) are receiving considerable attention as a cytotherapeutic for viral pneumonia. Several properties of MSCs position them as a promising therapeutic strategy for viral pneumonia-induced lung injury as demonstrated in pre-clinical studies in relevant models. More recently, early phase clinical studies have demonstrated a reassuring safety profile of these cells. These investigations have taken on an added importance and urgency during the COVID-19 pandemic, with multiple trials in progress across the globe. In parallel with clinical translation, strategies are being investigated to enhance the therapeutic potential of these cells in vivo, with different MSC tissue sources, specific cellular products including cell-free options, and strategies to ‘licence’ or ‘pre-activate’ these cells, all being explored. This review will assess the therapeutic potential of MSC-based therapies for severe viral pneumonia. It will describe the aetiology and epidemiology of severe viral pneumonia, describe current therapeutic approaches, and examine the data suggesting therapeutic potential of MSCs for severe viral pneumonia in pre-clinical and clinical studies. The challenges and opportunities for MSC-based therapies will then be considered.

Cell Therapy of Stroke: Do the Intra-Arterially Transplanted Mesenchymal Stem Cells Cross the Blood-Brain Barrier?

Animal model studies and first clinical trials have demonstrated the safety and efficacy of the mesenchymal stem cells' (MSCs) transplantation in stroke. Intra-arterial (IA) administration looks especially promising, since it provides targeted cell delivery to the ischemic brain, is highly effective, and can be safe as long as the infusion is conducted appropriately. However, wider clinical application of the IA MSCs transplantation will only be possible after a better understanding of the mechanism of their therapeutic action is achieved. On the way to achieve this goal, the study of transplanted cells' fate and their interactions with the blood-brain barrier (BBB) structures could be one of the key factors. In this review, we analyze the available data concerning one of the most important aspects of the transplanted MSCs' action-the ability of cells to cross the blood-brain barrier (BBB) in vitro and in vivo after IA administration into animals with experimental stroke. The collected data show that some of the transplanted MSCs temporarily attach to the walls of the cerebral vessels and then return to the bloodstream or penetrate the BBB and either undergo homing in the perivascular space or penetrate deeper into the parenchyma. Transmigration across the BBB is not necessary for the induction of therapeutic effects, which can be incited through a paracrine mechanism even by cells located inside the blood vessels.

Mesenchymal Stromal Cells: Potential Option for COVID-19 Treatment

The COVID-19 pandemic has significantly impacted the way of life worldwide and continues to bring high mortality rates to at-risk groups. Patients who develop severe COVID-19 pneumonia, often complicated with ARDS, are left with limited treatment options with no targeted therapy currently available. One of the features of COVID-19 is an overaggressive immune reaction that leads to multiorgan failure. Mesenchymal stromal cell (MSC) treatment has been in development for various clinical indications for over a decade, with a safe side effect profile and promising results in preclinical and clinical trials. Therefore, the use of MSCs in COVID-19-induced respiratory failure and ARDS was a logical step in order to find a potential treatment option for the most severe patients. In this review, the main characteristics of MSCs, their proposed mechanism of action in COVID-19 treatment and the effect of this therapy in published case reports and clinical trials are discussed.

Detection and quantification of human-specific mRNA from hepatocyte-like cells derived from dental pulp using real-time polymerase chain reaction

OBJECTIVES

We quantified viable hepatocyte-like cells (HLCs) administered via portal or tail veins in the livers and lungs of immunodeficient rats using real-time reverse transcription polymerase chain reaction (RT-PCR) and human glyceraldehyde 3-phosphate dehydrogenase (GAPDH) primers.

METHODS

Immunodeficient rats were infused with HLCs via portal or tail veins. mRNA was quantified based on the route of cell administration and the presence of liver injury.

RESULTS

Human-specific GAPDH mRNA primers detected 0.1 pg human RNA in 100 ng (1:10⁶) of rat liver RNA. When infused into the portal vein, the quantity of HLC mRNA reduced to 5% 3 hours after infusion. Most HLCs were entrapped in the lungs when infused via the tail vein and decreased to approximately 10% 6 hours after infusion. A small number of HLCs made it to the liver but disappeared rapidly, regardless of liver injury. 24 hours after infusion, viable HLCs were detected only in the lungs of rats with liver injury (P < 0.05).

CONCLUSIONS

The quantity of viable human cells in immunodeficient rats was estimated using real-time RT-PCR and primers specific to human mRNA.

Dissecting the Role of Mesenchymal Stem Cells in Idiopathic Pulmonary Fibrosis: Cause or Solution

Idiopathic pulmonary fibrosis (IPF) is one of the most aggressive forms of idiopathic interstitial pneumonias, characterized by chronic and progressive fibrosis subverting the lung's architecture, pulmonary functional decline, progressive respiratory failure, and high mortality (median survival 3 years after diagnosis). Among the mechanisms associated with disease onset and progression, it has been hypothesized that IPF lungs might be affected either by a regenerative deficit of the alveolar epithelium or by a dysregulation of repair mechanisms in response to alveolar and vascular damage. This latter might be related to the progressive dysfunction and exhaustion of the resident stem cells together with a process of cellular and tissue senescence. The role of endogenous mesenchymal stromal/stem cells (MSCs) resident in the lung in the homeostasis of these mechanisms is still a matter of debate. Although endogenous MSCs may play a critical role in lung repair, they are also involved in cellular senescence and tissue ageing processes with loss of lung regenerative potential. In addition, MSCs have immunomodulatory properties and can secrete anti-fibrotic factors. Thus, MSCs obtained from other sources administered systemically or directly into the lung have been investigated for lung epithelial repair and have been explored as a potential therapy for the treatment of lung diseases including IPF. Given these multiple potential roles of MSCs, this review aims both at elucidating the role of resident lung MSCs in IPF pathogenesis and the role of administered MSCs from other sources for potential IPF therapies.

Therapeutic mechanisms of mesenchymal stem cells in acute respiratory distress syndrome reveal potentials for Covid-19 treatment

The mortality rate of critically ill patients with acute respiratory distress syndrome (ARDS) is 30.9% to 46.1%. The emergence of the coronavirus disease 2019 (Covid-19) has become a global issue with raising dire concerns. Patients with severe Covid-19 may progress toward ARDS. Mesenchymal stem cells (MSCs) can be derived from bone marrow, umbilical cord, adipose tissue and so on. The easy accessibility and low immunogenicity enable MSCs for allogeneic administration, and thus they were widely used in animal and clinical studies. Accumulating evidence suggests that mesenchymal stem cell infusion can ameliorate ARDS. However, the underlying mechanisms of MSCs need to be discussed. Recent studies showed MSCs can modulate immune/inflammatory cells, attenuate endoplasmic reticulum stress, and inhibit pulmonary fibrosis. The paracrine cytokines and exosomes may account for these beneficial effects. In this review, we summarize the therapeutic mechanisms of MSCs in ARDS, analyzed the most recent animal experiments and Covid-19 clinical trial results, discussed the adverse effects and prospects in the recent studies, and highlight the potential roles of MSC therapy for Covid-19 patients with ARDS.

Potency of Mesenchymal Stem Cell and Its Secretome in Treating COVID-19

Abstract

The COVID-19 disease, which is caused by the novel coronavirus, SARS-CoV-2, has affected the world by increasing the mortality rate in 2020. Currently, there is no definite treatment for COVID-19 patients. Several clinical trials have been proposed to overcome this disease and many are still under investigation. In this review, we will be focusing on the potency of mesenchymal stem cells (MSCs) and MSC-derived secretome for treating COVID-19 patients. Fever, cough, headache, dizziness, and fatigue are the common clinical manifestations in COVID-19 patients. In mild and severe cases, cytokines are released hyper-actively which causes a cytokine storm leading to acute respiratory distress syndrome (ARDS). In order to maintain the lung microenvironment in COVID-19 patients, MSCs are used as cell-based therapy approaches as they can act as cell managers which accelerate the immune system to prevent the cytokine storm and promote endogenous repair. Besides, MSCs have shown minimal expression of ACE2 or TMPRSS2, and hence, MSCs are free from SARS-CoV-2 infection. Numerous clinical studies have started worldwide and demonstrated that MSCs have great potential for ARDS treatment in COVID-19 patients. Preliminary data have shown that MSCs and MSC-derived secretome appear to be promising in the treatment of COVID-19.

Lay Summary

The COVID-19 disease is an infection disease which affects the world in 2020. Currently, there is no definite treatment for COVID-19 patients. However, several clinical trials have been proposed to overcome this disease and one of them is using mesenchymal stem cells (MSCs) and MSC-derived secretome for treating COVID-19 patients. During the infection, cytokines are released hyper-actively which causes a cytokine storm. MSCs play an important role in maintaining the lung microenvironment in COVID-19 patients. They can act as cell managers which accelerate the immune system to prevent the cytokine storm and promote the endogenous repair. Therefore, it is important to explore the clinical trial in the world for treating the COVID-19 disease using MSCs and MSC-derived secretome.

Intra-vital imaging of mesenchymal stromal cell kinetics in the pulmonary vasculature during infection

Mesenchymal stem/stromal cells (MSCs) have demonstrated efficacy in pre-clinical models of inflammation and tissue injury, including in models of lung injury and infection. Rolling, adhesion and transmigration of MSCs appears to play a role during MSC kinetics in the systemic vasculature. However, a large proportion of MSCs become entrapped within the lungs after intravenous administration, while the initial kinetics and the site of arrest of MSCs in the pulmonary vasculature are unknown. We examined the kinetics of intravascularly administered MSCs in the pulmonary vasculature using a microfluidic system in vitro and intra-vital microscopy of intact mouse lung. In vitro, MSCs bound to endothelium under static conditions but not under laminar flow. VCAM-1 antibodies did not affect MSC binding. Intravital microscopy demonstrated MSC arrest at pulmonary micro-vessel bifurcations due to size obstruction. Retention of MSCs in the pulmonary microvasculature was increased in Escherichia coli-infected animals. Trapped MSCs deformed over time and appeared to release microvesicles. Labelled MSCs retained therapeutic efficacy against pneumonia. Our results suggest that MSCs are physically obstructed in pulmonary vasculature and do not display properties of rolling/adhesion, while retention of MSCs in the infected lung may require receptor interaction.

Multipotent Mesenchymal Stromal Cells in Rheumatoid Arthritis and Systemic Lupus Erythematosus; From a Leading Role in Pathogenesis to Potential Therapeutic Saviors?

The pathogenesis of the autoimmune rheumatological diseases including rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) is complex with the involvement of several immune cell populations spanning both innate and adaptive immunity including different T-lymphocyte subsets and monocyte/macrophage lineage cells. Despite therapeutic advances in RA and SLE, some patients have persistent and stubbornly refractory disease. Herein, we discuss stromal cells' dual role, including multipotent mesenchymal stromal cells (MSCs) also used to be known as mesenchymal stem cells as potential protagonists in RA and SLE pathology and as potential therapeutic vehicles. Joint MSCs from different niches may exhibit prominent pro-inflammatory effects in experimental RA models directly contributing to cartilage damage. These stromal cells may also be key regulators of the immune system in SLE. Despite these pro-inflammatory roles, MSCs may be immunomodulatory and have potential therapeutic value to modulate immune responses favorably in these autoimmune conditions. In this review, the complex role and interactions between MSCs and the haematopoietically derived immune cells in RA and SLE are discussed. The harnessing of MSC immunomodulatory effects by contact-dependent and independent mechanisms, including MSC secretome and extracellular vesicles, is discussed in relation to RA and SLE considering the stromal immune microenvironment in the diseased joints. Data from translational studies employing MSC infusion therapy against inflammation in other settings are contextualized relative to the rheumatological setting. Although safety and proof of concept studies exist in RA and SLE supporting experimental and laboratory data, robust phase 3 clinical trial data in therapy-resistant RA and SLE is still lacking.

Mesenchymal Stromal Cells Rapidly Suppress TCR Signaling-Mediated Cytokine Transcription in Activated T Cells Through the ICAM-1/CD43 Interaction

Cell-cell contact participates in the process of mesenchymal stromal cell (MSC)-mediated T cell modulation and thus contributes to MSC-based therapies for various inflammatory diseases, especially T cell-mediated diseases. However, the mechanisms underlying the adhesion interactions between MSCs and T cells are still poorly understood. In this study, we explored the interaction between MSCs and T cells and found that activated T cells could rapidly adhere to MSCs, leading to significant reduction of TNF-α and IFN-γ mRNA expression. Furthermore, TCR-proximal signaling in activated T cells was also dramatically suppressed in the MSC co-culture, resulting in weakened Ca²⁺ signaling. MSCs rapidly suppressed TCR signaling and its downstream signaling in a cell-cell contact-dependent manner, partially through the ICAM-1/CD43 adhesion interaction. Blockade of either ICAM-1 on MSCs or CD43 on T cells significantly reversed this rapid suppression of proinflammatory cytokine expression in T cells. Mechanistically, MSC-derived ICAM-1 likely disrupts CD43-mediated TCR microcluster formation to limit T cell activation. Taken together, our results reveal a fast mechanism of activated T cell inhibition by MSCs, which provides new clues to unravel the MSC-mediated immunoregulatory mechanism for aGVHD and other severe acute T cell-related diseases.

Therapeutic Potential of Mesenchymal Stem Cells and Their Products in Lung Diseases-Intravenous Administration versus Inhalation

The number of publications studying the therapeutic use of stem cells has steadily increased since 2000. Compared to other applications, there has been little interest in the evaluation of mesenchymal stem cells (MSCs) and MSC-derived products (mostly extracellular vesicles) for the treatment of respiratory diseases. Due to the lack of efficient treatments for acute respiratory distress syndrome caused by infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the action of MSCs has also been studied. This review describes mode of action and use of MSCs and MSC-derived products in the treatment of lung diseases including the respective advantages and limitations of the products. Further, issues related to standardized production are addressed. Administration by inhalation of MSCs, compared to intravenous injection, could decrease cell damage by shear stress, eliminate the barrier to reach target cells in the alveoli, prevent thrombus formation in the pulmonary vasculature and retention in filter for extracorporeal membrane oxygenation. There is more feasible to deliver extracellular vesicles than MSCs with inhalers, offering the advantage of non-invasive and repeated administration by the patient. Major obstacles for comparison of results are heterogeneity of the products, differences in the treatment protocols and small study cohorts.

Intravital Imaging of Pulmonary Immune Response in Inflammation and Infection

Intravital microscopy (IVM) is a unique imaging method providing insights in cellular functions and interactions in real-time, without the need for tissue extraction from the body. IVM of the lungs has specific challenges such as restricted organ accessibility, respiratory movements, and limited penetration depth. Various surgical approaches and microscopic setups have been adapted in order to overcome these challenges. Among others, these include the development of suction stabilized lung windows and the use of more advanced optical techniques. Consequently, lung IVM has uncovered mechanisms of leukocyte recruitment and function in several models of pulmonary inflammation and infection. This review focuses on bacterial pneumonia, aspiration pneumonia, sepsis-induced acute lung Injury, and cystic fibrosis, as examples of lung inflammation and infection. In addition, critical details of intravital imaging techniques of the lungs are discussed.

Cross-matching of allogeneic mesenchymal stromal cells eliminates recipient immune targeting

Allogeneic mesenchymal stromal cells (MSCs) have been used clinically for decades, without cross-matching, on the assumption that they are immune-privileged. In the equine model, we demonstrate innate and adaptive immune responses after repeated intra-articular injection with major histocompatibility complex (MHC) mismatched allogeneic MSCs, but not MHC matched allogeneic or autologous MSCs. We document increased peri-articular edema and synovial effusion, increased synovial cytokine and chemokine concentrations, and development of donor-specific antibodies in mismatched recipients compared with recipients receiving matched allogeneic or autologous MSCs. Importantly, in matched allogeneic and autologous recipients, but not mismatched allogeneic recipients, there was increased stromal derived factor-1 along with increased MSC concentrations in synovial fluid. Until immune recognition of MSCs can be avoided, repeated clinical use of MSCs should be limited to autologous or cross-matched allogeneic MSCs. When non-cross-matched allogeneic MSCs are used in single MSC dose applications, presensitization against donor MHC should be assessed.

IL-37 Exerts Anti-Inflammatory Effects in Fetal Membranes of Spontaneous Preterm Birth via the NF-κB and IL-6/STAT3 Signaling Pathway

Spontaneous preterm birth (sPTB), defined as delivery before 37 weeks of gestation, is thought to be a multifactorial syndrome. However, the inflammatory imbalance at the maternal-fetal interface promotes excessive secretion of inflammatory factors and induces apoptosis and degradation of the extracellular matrix (ECM), which can subsequently lead to preterm birth. As an anti-inflammatory molecule in the IL-1 family, interleukin-37 (IL-37) mainly plays an inhibiting role in a variety of inflammatory diseases. However, as a typical inflammatory disease, no previous studies have been carried out to explore the role of IL-37 in sPTB. In this study, a series of molecular biological experiments were performed in clinical samples and human amniotic epithelial cell line (Wistar Institute Susan Hayflick (WISH)) to investigate the deficiency role of IL-37 and the potential mechanism. Firstly, the results indicated that the expression of IL-37 in human peripheral plasma and fetal membranes was significantly decreased in the sPTB group. Afterward, it is proved that IL-37 could significantly suppress the production of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) in WISH cells. Simultaneously, once silence IL-37, LPS-induced apoptosis and activity of matrix metalloproteinases (MMPs) 2 and 9 were significantly increased. In addition, the western blot data showed that IL-37 performed its biological effects by inhibiting the NF-κB and IL-6/STAT3 pathway. In conclusion, our results suggest that IL-37 limits excessive inflammation and subsequently inhibits ECM remodeling and apoptosis through the NF-κB and IL-6/STAT3 signaling pathway in the fetal membranes.

Anti-fibrotic mechanisms of exogenously-expanded mesenchymal stromal cells for fibrotic diseases

Most chronic diseases involving inflammation have a fibrotic component that involves remodeling and excess accumulation of extracellular matrix components. Left unchecked, fibrosis leads to organ failure and death. Mesenchymal stromal cells (MSCs) are emerging as a potent cell-based therapy for a wide spectrum of fibrotic conditions due to their immunomodulatory, anti-inflammatory and anti-fibrotic properties. This review provides an overview of known mechanisms by which MSCs mediate their anti-fibrotic actions and in relation to animal models of pulmonary, liver, renal and cardiac fibrosis. Recent MSC clinical trials results in liver, lung, skin, kidney and hearts are discussed and next steps for future MSC-based therapies including pre-activated or genetically-modified cells, or extracellular vesicles are also considered.

Therapies from Fucoidan: New Developments

Since our last review in 2015, the study and use of fucoidan has extended in several research areas. Clinical use of fucoidan for the treatment of renal disease has become available and human safety studies have been undertaken on radiolabeled fucoidan for the purpose of imaging thrombi. Fucoidan has been incorporated into an increasing number of commercially available supplements and topical treatments. In addition, new measuring techniques are now available to assess the biologically relevant uptake of fucoidans and to assist in production. Microbiome modulation and anti-pathogenic effects are increasingly promising applications for fucoidans, due to the need for alternative approaches to antibiotic use in the food chain. This review outlines promising new developments in fucoidan research, including potential future therapeutic use.