Interplay between mesenchymal stromal cells and the immune system after transplantation: implications for advanced cell therapy in the retina

Advanced mesenchymal stromal cell-based therapies for neurodegenerative diseases are widely investigated in preclinical models.Mesenchymal stromal cells are well positioned as therapeutics because they address the underlying mechanisms of neurodegeneration,namely trophic factor deprivation and neuroinflammation.Most studies have focused on the beneficial effects of mesenchymal stromal cell transplantation on neuronal survival or functional improvement.However,little attention has been paid to the interaction between mesenchymal stromal cells and the host immune system due to the immunomodulatory properties of mesenchymal stromal cells and the long-held belief of the immunoprivileged status of the central nervous system.Here,we review the crosstalk between mesenchymal stromal cells and the immune system in general and in the context of the central nervous system,focusing on recent work in the retina and the importance of the type of transplantation.

Exosomes from umbilical cord mesenchymal stromal cells promote the collagen production of fibroblasts from pelvic organ prolapse

BACKGROUND Pelvic organ prolapse(POP)involves pelvic organ herniation into the vagina due to pelvic floor tissue laxity,and vaginal structure is an essential factor.In POP,the vaginal walls exhibit abnormal collagen distribution and decreased fibroblast levels and functions.The intricate etiology of POP and the prohibition of trans-vaginal meshes in pelvic reconstruction surgery present challenges in targeted therapy development.Human umbilical cord mesenchymal stromal cells(hucMSCs)present limitations,but their exosomes(hucMSC-Exo)are promising therapeutic tools for promoting fibroblast proliferation and extracellular matrix remodeling.suppressed inflammation in POP group fibroblasts,stimulated primary fibroblast growth,and elevated collagen I(Col1)production in vitro.High-throughput RNA-seq of fibroblasts treated with hucMSC-Exo and miRNA sequencing of hucMSC-Exo revealed that abundant exosomal miRNAs downregulated matrix metalloproteinase 11(MMP11)expression.CONCLUSION HucMSC-Exo normalized the growth and function of primary fibroblasts from patients with POP by promoting cell growth and Col1 expression in vitro.Abundant miRNAs in hucMSC-Exo targeted and downregulated MMP11 expression.HucMSC-Exo-based therapy may be ideal for safely and effectively treating POP.

Mesenchymal stromal cells modulate unfolded protein response and preserve β-cell mass in type 1 diabetes

Introduction:Transplantation of mesenchymal stromal cells(MSCs)is a promising therapy for type 1 diabetes(T1D).However,whether the infused MSCs affect the endoplasmic reticulum stress or subsequent unfolded protein response inβcells remains unclear.Methods:To investigate this,we induced early-onset T1D in non-obese diabetic mice using streptozotocin.Subsequently,T1D mice were randomly assigned to receive either MSCs or phosphate-buffered saline.We observed the in vivo homing of MSCs and assessed their effectiveness by analyzing blood glucose levels,body weight,histopathology,pancreatic protein expression,and serum levels of cytokines,proinsulin,and C-peptide.Results:Infused MSCs were found in the lungs,liver,spleen,and pancreas of T1D mice.They exhibited various effects,including reducing blood glucose levels,regulating immunity,inhibiting inflammation,increasingβ-cell areas,and reducing the expression of key proteins in the unfolded protein response pathway.Fasting serum proinsulin and C-peptide levels were significantly higher in the MSCs treatment group than in the T1D model group.However,there was no significant difference in the biomarker ofβ-cell endoplasmic reticulum stress,the ratio of fasting serum proinsulin to C-peptide,between the two groups.Conclusion:Ourfindings reveal that MSCs infusion does not alleviate endoplasmic reticulum stress inβcells directly but modulates the unfolded protein response pathway to preserveβ-cell mass and function in T1D mice.

O-linkedβ-N-acetylglucosaminylation may be a key regulatory factor in promoting osteogenic differentiation of bone marrow mesenchymal stromal cells

Cumulative evidence suggests that O-linkedβ-N-acetylglucosaminylation(OGlcNAcylation)plays an important regulatory role in pathophysiological processes.Although the regulatory mechanisms of O-GlcNAcylation in tumors have been gradually elucidated,the potential mechanisms of O-GlcNAcylation in bone metabolism,particularly,in the osteogenic differentiation of bone marrow mesenchymal stromal cells(BMSCs)remains unexplored.In this study,the literature related to O-GlcNAcylation and BMSC osteogenic differentiation was reviewed,assuming that it could trigger more scholars to focus on research related to OGlcNAcylation and bone metabolism and provide insights into the development of novel therapeutic targets for bone metabolism disorders such as osteoporosis.

Mesenchymal Stromal Cells and Their Uses in Bio-Regenerative Therapies for Bone and Cartilage: A Review

Mesenchymal stromal cells (MSCs) are a top candidate for new clinical treatments in the repair of bone and cartilage. In several clinical trials, they have shown reliable, effective, and safe management of inflammation, pain, and the regenerative capabilities of resident tissues. MSCs are likely derived from pericytes. They modulate the environment they are placed in by secreting immunomodulatory and signaling molecules to reduce inflammation and direct resident cells to create new tissues. They are easily isolated from several different adult tissues, and inexpensive to grow in a lab. However, a mistake made in the initial classification of MSCs as stem cells has created deeply engrained misconceptions that are still evident today. MSCs are not stem cells, despite a large fraction of research and therapies using the name “mesenchymal stem cells”. This mistake creates false narratives attributing the observed positive outcomes of MSC treatments to stem cell characteristics, which has led to distrust in MSC research. Despite inconsistencies in their classification, MSCs demonstrate consistent positive effects in numerous animal studies and human clinical trials for non-unions and osteoarthritis. With an aging population, regenerative techniques are very promising for novel therapies. To produce trusted and safe new treatments using MSCs, it is essential for the International Society for Cellular Therapies to re-establish common ground in the identity, mechanism of action, and isolation techniques of these cells.

Is mandible derived mesenchymal stromal cells superior in proliferation and regeneration to long bone-derived mesenchymal stromal cells?

Mesenchymal stromal cells(MSCs)are cells with the characteristic ability of self-renewal along with the ability to exhibit multilineage differentiation.Bone marrow(BM)is the first tissue in which MSCs were identified and BM-MSCs are most commonly used among various MSCs in clinical settings.MSCs can stimulate and promote osseous regeneration.Due to the difference in the development of long bones and craniofacial bones,the mandibular-derived MSCs(M-MSCs)have distinct differentiation characteristics as compared to that of long bones.Both mandibular and long bone-derived MSCs are positive for MSC-associated markers such as CD-73,-105,and-106,stage-specific embryonic antigen 4 and Octamer-4,and negative for hematopoietic markers such as CD-14.

Commitment of human mesenchymal stromal cells to skeletal lineages is independent of their morphogenetic capacity

BACKGROUND Mesenchymal stromal cells(MSCs)are multipotent cell populations obtained from fetal and adult tissues.They share some characteristics with limb bud mesodermal cells such as differentiation potential into osteogenic,chondrogenic,and tenogenic lineages and an embryonic mesodermal origin.Although MSCs differentiate into skeletal-related lineages in vitro,they have not been shown to selforganize into complex skeletal structures or connective tissues,as in the limb.In this work,we demonstrate that the expression of molecular markers to commit MSCs to skeletal lineages is not sufficient to generate skeletal elements in vivo.AIM To evaluate the potential of MSCs to differentiate into skeletal lineages and generate complex skeletal structures using the recombinant limb(RL)system.METHODS We used the experimental system of RLs from dissociated-reaggregated human placenta(PL)and umbilical cord blood(UCB)MSCs.After being harvested and reaggregated in a pellet,cultured cells were introduced into an ectodermal cover obtained from an early chicken limb bud.Next,this filled ectoderm was grafted into the back of a donor chick embryo.Under these conditions,the cells received and responded to the ectoderm’s embryonic signals in a spatiotemporal manner to differentiate and pattern into skeletal elements.Their response to differentiation and morphogenetic signals was evaluated by quantitative poly-merase chain reaction,histology,immunofluorescence,scanning electron microscopy,and in situ hybridization.RESULTS We found that human PL-MSCs and UCB-MSCs constituting the RLs expressed chondrogenic,osteogenic,and tenogenic molecular markers while differentially committing into limb lineages but could not generate complex structures in vivo.MSCs-RL from PL or UCB were committed early to chondrogenic lineage.Nevertheless,the UCB-RL osteogenic commitment was favored,although preferentially to a tenogenic cell fate.These findings suggest that the commitment of MSCs to differentiate into skeletal lineages differs according to the source and is independent of their capacity to generate skeletal elements or connective tissue in vivo.Our results suggest that the failure to form skeletal structures may be due to the intrinsic characteristics of MSCs.Thus,it is necessary to thoroughly evaluate the biological aspects of MSCs and how they respond to morphogenetic signals in an in vivo context.CONCLUSION PL-MSCs and UCB-MSCs express molecular markers of differentiation into skeletal lineages,but they are not sufficient to generate complex skeletal structures in vivo.

Constitutive aryl hydrocarbon receptor facilitates the regenerative potential of mouse bone marrow mesenchymal stromal cells

BACKGROUND Bone marrow mesenchymal stromal cells(BMSCs)are the commonly used seed cells in tissue engineering.Aryl hydrocarbon receptor(AhR)is a transcription factor involved in various cellular processes.However,the function of constitutive AhR in BMSCs remains unclear.AIM To investigate the role of AhR in the osteogenic and macrophage-modulating potential of mouse BMSCs(mBMSCs)and the underlying mechanism.METHODS Immunochemistry and immunofluorescent staining were used to observe the expression of AhR in mouse bone marrow tissue and mBMSCs.The overexpression or knockdown of AhR was achieved by lentivirus-mediated plasmid.The osteogenic potential was observed by alkaline phosphatase and alizarin red staining.The mRNA and protein levels of osteogenic markers were detected by quantitative polymerase chain reaction(qPCR)and western blot.After coculture with different mBMSCs,the cluster of differentiation(CD)86 and CD206 expressions levels in RAW 264.7 cells were analyzed by flow cytometry.To explore the underlying molecular mechanism,the interaction of AhR with signal transducer and activator of transcription 3(STAT3)was observed by co-immunoprecipitation and phosphorylation of STAT3 was detected by western blot.RESULTS AhR expressions in mouse bone marrow tissue and isolated mBMSCs were detected.AhR overexpression enhanced the osteogenic potential of mBMSCs while AhR knockdown suppressed it.The ratio of CD86+RAW 264.7 cells cocultured with AhR-overexpressed mBMSCs was reduced and that of CD206+cells was increased.AhR directly interacted with STAT3.AhR overexpression increased the phosphorylation of STAT3.After inhibition of STAT3 via stattic,the promotive effects of AhR overexpression on the osteogenic differentiation and macrophage-modulating were partially counteracted.CONCLUSION AhR plays a beneficial role in the regenerative potential of mBMSCs partially by increasing phosphorylation of STAT3.

Comparative effectiveness of adipose-derived mesenchymal stromal cells in the management of knee osteoarthritis:A meta-analysis

BACKGROUND Osteoarthritis(OA)is the most common joint disorder,is associated with an increasing socioeconomic impact owing to the ageing population.AIM To analyze and compare the efficacy and safety of bone-marrow-derived mesenchymal stromal cells(BM-MSCs)and adipose tissue-derived MSCs(AD-MSCs)in knee OA management from published randomized controlled trials(RCTs).METHODS Independent and duplicate electronic database searches were performed,including PubMed,EMBASE,Web of Science,and Cochrane Library,until August 2021 for RCTs that analyzed the efficacy and safety of AD-MSCs and BM-MSCs in the management of knee OA.The visual analog scale(VAS)score for pain,Western Ontario McMaster Universities Osteoarthritis Index(WOMAC),Lysholm score,Tegner score,magnetic resonance observation of cartilage repair tissue score,knee osteoarthritis outcome score(KOOS),and adverse events were analyzed.Analysis was performed on the R-platform using OpenMeta(Analyst)software.Twenty-one studies,involving 936 patients,were included.Only one study compared the two MSC sources without patient randomization;hence,the results of all included studies from both sources were pooled,and a comparative critical analysis was performed.RESULTS At six months,both AD-MSCs and BM-MSCs showed significant VAS improvement(P=0.015,P=0.012);this was inconsistent at 1 year for BM-MSCs(P<0.001,P=0.539),and AD-MSCs outperformed BM-MSCs compared to controls in measures such as WOMAC(P<0.001,P=0.541),Lysholm scores(P=0.006;P=0.933),and KOOS(P=0.002;P=0.012).BM-MSC-related procedures caused significant adverse events(P=0.003)compared to AD-MSCs(P=0.673).CONCLUSION Adipose tissue is superior to bone marrow because of its safety and consistent efficacy in improving pain and functional outcomes.Future trials are urgently warranted to validate our findings and reach a consensus on the ideal source of MSCs for managing knee OA.

Comparison of human amniotic fluid-derived and umbilical cord Wharton＇s Jelly-derived mesenchymal stromal cells： Characterization and myocardial differentiation capacity

Objective To compare the characterization and myocardial differentiation capacity of arnniotic fluid-derived mesenchymal stromal cells （AF MSCs） and umbilical cord Wharton＇s Jelly-derived mesenchymal stromal cells （WJ MSCs）. Methods The human AF MSCs were cultured from amniotic fluid samples obtained by amniocentesis. The umbilical cord WJ MSCs were obtained from Wharton＇s Jelly of umbilical cords of infants delivered full-term by normal labor. The morphology, growth curves, and analyses by flow cytometry of cell surface markers were compared between the two types of cells. Myocardial genes （GATA-4, c-TnT, a-actin, and Cx43） were detected by real-time PCR and the corresponding protein expressions were detected by Western blot analysis after myocardial induced in AF MSCs and WJ MSCs. Results Our findings revealed AF MSCs and WJ MSCs shared similar morphological characteristics of the fibroblastoid shape. The AF MSCs were easily obtained than the WJ MSCs and had a shorter time to reach adherence of 2.7 ± 1.6 days to WJ MSCs of 6.5 ± 1.8 days. The growth curves by MTT cytotoxic assay showed the AF MSCs had a similar proliferative capacity at passage 5 and passage 10. However, the proliferative capacities ofWJ MSCs were decreased at 5 passage relative to 10 passage. Both AF stem cells and WJ stem cells had the characteristics of mesenchymal stromal cells with some characteristics of embryonic stem cells. They express CD29 and CD105, but not CD34. They were positive for Class I major histocompatibility （MHC I） antigens （HLA-ABC）, and were negative, or mildly positive, for MHC Class II （HLA-DR） antigen. Oct-4 was positive in all the two cells types. Both AF MSCs and WJ MSCs could differentiate along myocardium. The differentiation capacities were detected by the expression of GATA-4, c-TnT, a-actin, Cx43 after myocardial induction. Conclusions Both AF MSCs and WJ MSCs have the potential clinical application for myogenesis in cardiac regenerative therapy.

Mesenchymal stromal cells' role in tumor microenvironment:involvement of signaling pathways

Mesenchymal stromal cells(MSCs) are adult multipotent stem cells residing as pericytes in various tissues and organs where they can differentiate into specialized cells to replace dying cells and damaged tissues. These cells are commonly found at injury sites and in tumors that are known to behave like "wounds that do not heal." In this article, we discuss the mechanisms of MSCs in migrating, homing, and repairing injured tissues. We also review a number of reports showing that tumor microenvironment triggers plasticity mechanisms in MSCs to induce malignant neoplastic tissue formation, maintenance, and chemoresistance, as well as tumor growth. The antitumor properties and therapeutic potential of MSCs are also discussed.

Mesenchymal stromal cells as potential immunomodulatory players in severe acute respiratory distress syndrome induced by SARSCoV- 2 infection

Severe acute respiratory syndrome coronavirus-2 and the related coronavirus disease-19(COVID-19)is a worldwide emerging situation,which was initially reported in December 2019 in Wuhan,China.Currently,more than 7258842 new cases,and more than 411879 deaths have been reported globally.This new highly transmitted coronavirus is responsible for the development of severe acute respiratory distress syndrome.Due to this disorder,a great number of patients are hospitalized in the intensive care unit followed by connection to extracorporeal membrane oxygenation for breath supporting and survival.Severe acute respiratory distress syndrome is mostly accompanied by the secretion of proinflammatory cytokines,including interleukin(IL)-2,IL-6,IL-7,granulocyte colony-stimulating factor(GSCF),interferon-inducible protein 10(IP10),monocyte chemotactic protein-1(MCP1),macrophage inflammatory protein 1A(MIP1A),and tumor necrosis factor alpha(TNF-α),an event which is known as“cytokine storm”.Further disease pathology involves a generalized modulation of immune responses,leading to fatal multiorgan failure.Currently,no specific treatment or vaccination against severe acute respiratory syndrome coronavirus-2(SARS-CoV-2)has been developed.Mesenchymal stromal cells(MSCs),which are known for their immunosuppressive actions,could be applied as an alternative co-therapy in critically-ill COVID-19 patients.Specifically,MSCs can regulate the immune responses through the conversion of Th1 to Th2,activation of M2 macrophages,and modulation of dendritic cells maturation.These key immunoregulatory properties of MSCs may be exerted either by produced soluble factors or by cell-cell contact interactions.To date,several clinical trials have been registered to assess the safety,efficacy,and therapeutic potential of MSCs in COVID-19.Moreover,MSC treatment may be effective for the reversion of ground-glass opacity of damaged lungs and reduce the tissue fibrosis.Taking into account the multifunctional properties of MSCs,the proposed stem-cell-based therapy may be proven significantly effective in critically-ill COVID-19 patients.The current therapeutic strategy may improve the patient’s overall condition and in parallel may decrease the mortality rate of the current disease.

Effects of living and metabolically inactive mesenchymal stromal cells and their derivatives on monocytes and macrophages

Mesenchymal stromal cells (MSCs) are multipotent and self-renewing stem cellsthat have great potential as cell therapy for autoimmune and inflammatorydisorders, as well as for other clinical conditions, due to their immunoregulatoryand regenerative properties. MSCs modulate the inflammatory milieu by releasingsoluble factors and acting through cell-to-cell mechanisms. MSCs switch theclassical inflammatory status of monocytes and macrophages towards a nonclassicaland anti-inflammatory phenotype. This is characterized by an increasedsecretion of anti-inflammatory cytokines, a decreased release of pro-inflammatorycytokines, and changes in the expression of cell membrane molecules and inmetabolic pathways. The MSC modulation of monocyte and macrophage phenotypesseems to be critical for therapy effectiveness in several disease models, sincewhen these cells are depleted, no immunoregulatory effects are observed. Here,we review the effects of living MSCs (metabolically active cells) and metabolicallyinactive MSCs (dead cells that lost metabolic activity by induced inactivation) andtheir derivatives (extracellular vesicles, soluble factors, extracts, and microparticles)on the profile of macrophages and monocytes and the implications forimmunoregulatory and reparative processes. This review includes mechanisms ofaction exhibited in these different therapeutic appro-aches, which induce the antiinflammatoryproperties of monocytes and macrophages. Finally, we overviewseveral possibilities of therapeutic applications of these cells and their derivatives,with results regarding monocytes and macrophages in animal model studies andsome clinical trials.

Novel insights for improving the therapeutic safety and efficiency of mesenchymal stromal cells

Mesenchymal stromal cells(MSCs)have attracted great interest in the field of regenerative medicine.They can home to damaged tissue,where they can exert pro-regenerative and anti-inflammatory properties.These therapeutic effects involve the secretion of growth factors,cytokines,and chemokines.Moreover,the functions of MSCs could be mediated by extracellular vesicles(EVs)that shuttle various signaling messengers.Although preclinical studies and clinical trials have demonstrated promising therapeutic results,the efficiency and the safety of MSCs need to be improved.After transplantation,MSCs face harsh environmental conditions,which likely dampen their therapeutic efficacy.A possible strategy aiming to improve the survival and therapeutic functions of MSCs needs to be developed.The preconditioning of MSCs ex vivo would strength their capacities by preparing them to survive and to better function in this hostile environment.In this review,we will discuss several preconditioning approaches that may improve the therapeutic capacity of MSCs.As stated above,EVs can recapitulate the beneficial effects of MSCs and may help avoid many risks associated with cell transplantation.As a result,this novel type of cell-free therapy may be safer and more efficient than the whole cell product.We will,therefore,also discuss current knowledge regarding the therapeutic properties of MSC-derived EVs.

Barriers to mesenchymal stromal cells for low back pain

Intervertebral disc degeneration is the main cause of low back pain.In the past 20 years,the injection of mesenchymal stromal cells(MSCs)into the nucleus pulposus of the degenerative disc has become the main approach for the treatment of low back pain.Despite the progress made in this field,there are still many barriers to overcome.First,intervertebral disc is a highly complex loadbearing composite tissue composed of annulus fibrosus,nucleus pulposus and cartilaginous endplates.Any structural damage will change its overall biomechanical function,thereby causing progressive degeneration of the entire intervertebral disc.Therefore,MSC-based treatment strategies should not only target the degenerated nucleus pulposus but also include degenerated annulus fibrosus or cartilaginous endplates.Second,to date,there has been relatively little research on the basic biology of annulus fibrosus and cartilaginous endplates,although their pathological changes such as annular tears or fissures,Modic changes,or Schmorl's nodes are more commonly associated with low back pain.Given the high complexity of the structure and composition of the annulus fibrosus and cartilaginous endplates,it remains an open question whether any regeneration techniques are available to achieve their restorative regeneration.Finally,due to the harsh microenvironment of the degenerated intervertebral disc,the delivered MSCs die quickly.Taken together,current MSC-based regenerative medicine therapies to regenerate the entire disc complex by targeting the degenerated nucleus pulposus alone are unlikely to be successful.

Effects of amyloid precursor protein peptide APP96-110,alone or with human mesenchymal stromal cells,on recovery after spinal cord injury

Delivery of a peptide(APP96-110),derived from amyloid precursor protein(APP),has been shown to elicit neuroprotective effects following cerebral stroke and traumatic brain injury.In this study,the effect of APP96-110 or a mutant version of this peptide(mAPP96-110)was assessed following moderate(200 kdyn,(2 N))thoracic contusive spinal cord injury(SCI)in adult Nude rats.Animals received a single tail vein injection of APP96-110 or mAPP96-110 at 30 minutes post-SCI and were then assessed for functional improvements over the next 8 weeks.A cohort of animals also received transplants of either viable or non-viable human mesenchymal stromal cells(hMSCs)into the SC lesion site at one week post-injury to assess the effect of combining intravenous APP96-110 delivery with hMSC treatment.Rats were perfused 8 weeks post-SCI and longitudinal sections of spinal cord analyzed for a number of factors including hMSC viability,cyst size,axonal regrowth,glial reactivity and macrophage activation.Analysis of sensorimotor function revealed occasional significant differences between groups using Ladderwalk or Ratwalk tests,however there were no consistent improvements in functional outcome after any of the treatments.mAPP96-110 alone,and APP96-110 in combination with both viable and non-viable hMSCs significantly reduced cyst size compared to SCI alone.Combined treatments with donor hMSCs also significantly increased βIII tubulin^(+),glial fibrillary acidic protein(GFAP^(+))and laminin+expression,and decreased ED1^(+)expression in tissues.This preliminary study demonstrates that intravenous delivery of APP96-110 peptide has selective,modest neuroprotective effects following SCI,which may be enhanced when combined with hMSC transplantation.However,the effects are less pronounced and less consistent compared to the protective morphological and cognitive impact that this same peptide has on neuronal survival and behaviour after stroke and traumatic brain injury.Thus while the efficacy of a particular therapeutic approach in one CNS injury model may provide justification for its use in other neurotrauma models,similar outcomes may not necessarily occur and more targeted approaches suited to location and severity are required.All animal experiments were approved by The University of Western Australia Animal Ethics Committee(RA3/100/1460)on April 12,2016.

Immunophenotypic characteristics of multipotent mesenchymal stromal cells that affect the efficacy of their use in the prevention of acute graft vs host disease

BACKGROUND Multipotent mesenchymal stromal cells(MSCs)are widely used in the clinic due to their unique properties,namely,their ability to differentiate in all mesenchymal directions and their immunomodulatory activity.Healthy donor MSCs were used to prevent the development of acute graft vs host disease(GVHD)after allogeneic bone marrow transplantation(allo-BMT).The administration of MSCs to patients was not always effective.The MSCs obtained from different donors have individual characteristics.The differences between MSC samples may affect their clinical efficacy.AIM To study the differences between effective and ineffective MSCs.METHODS MSCs derived from the bone marrow of a hematopoietic stem cells donor were injected intravenously into allo-BMT recipients for GVHD prophylaxis at the moment of blood cell reconstitution.Aliquots of 52 MSC samples that were administered to patients were examined,and the same cells were cultured in the presence of peripheral blood mononuclear cells(PBMCs)from a third-party donor or treated with the pro-inflammatory cytokines IL-1β,IFN and TNF.Flow cytometry revealed the immunophenotype of the nontreated MSCs,the MSCs cocultured with PBMCs for 4 d and the MSCs exposed to cytokines.The proportions of CD25-,CD146-,CD69-,HLA-DR-and PD-1-positive CD4+and CD8+cells and the distribution of various effector and memory cell subpopulations in the PBMCs cocultured with the MSCs were also determined.RESULTS Differences in the immunophenotypes of effective and ineffective MSCs were observed.In the effective samples,the mean fluorescence intensity(MFI)of HLAABC,HLA-DR,CD105,and CD146 was significantly higher.After MSCs were treated with IFN or cocultured with PBMCs,the HLA-ABC,HLA-DR,CD90 and CD54 MFI showed a stronger increase in the effective MSCs,which indicated an increase in the immunomodulatory activity of these cells.When PBMCs were cocultured with effective MSCs,the proportions of CD4+and CD8+central memory cells significantly decreased,and the proportion of CD8+CD146+lymphocytes increased more than in the subpopulations of lymphocytes cocultured with MSC samples that were ineffective in the prevention of GVHD;in addition,the proportion of CD8+effector memory lymphocytes decreased in the PBMCs cocultured with the effective MSC samples but increased in the PBMCs cocultured with the ineffective MSC samples.The proportion of CD4+CD146+lymphocytes increased only when cocultured with the inefficient samples.CONCLUSION For the first time,differences were observed between MSC samples that were effective for GVHD prophylaxis and those that were ineffective.Thus,it was shown that the immunomodulatory activity of MSCs depends on the individual characteristics of the MSC population.

Applications of scaffolds:Tools for enhancing the immunomodulation of mesenchymal stromal cells

Exogenously delivered mesenchymal stromal cells(MSCs)are therapeutically beneficial owing to their paracrine effect;they secrete various cytokines,nucleic acids,and proteins.Multiple bioengineering techniques can help MSC cultures to release secretomes by providing stem cell niche-like conditions(both structurally and functionally).Various scaffolds mimic the natural extracellular matrix(ECM)using both natural and synthetic polymers,providing favorable environments for MSC proliferation and differentiation.Depending on material properties,either topographically or elastically structured scaffolds can be fabricated.Three-dimensional scaffolds have tunable substrate rigidities and structures,aiding MSC cultivation.Decellularized ECM-derived hydrogels are similar to the natural ECM,thus improving the paracrine effects of MSCs.Here,we discuss recent research on the application of scaffolds to maximize the immunomodulatory function of MSCs.

Optimization of adipose tissue-derived mesenchymal stromal cells transplantation for bone marrow repopulation following irradiation

BACKGROUND Bone marrow(BM)suppression is one of the most common side effects of radiotherapy and the primary cause of death following exposure to irradiation.Despite concerted efforts,there is no definitive treatment method available.Recent studies have reported using mesenchymal stromal cells(MSCs),but their therapeutic effects are contested.AIM We administered and examined the effects of various amounts of adipose-derived MSCs(ADSCs)in mice with radiation-induced BM suppression.METHODS Mice were divided into three groups:Normal control group,irradiated(RT)group,and stem cell-treated group following whole-body irradiation(WBI).Mouse ADSCs(mADSCs)were transplanted into the peritoneal cavity either once or three times at 5×10^(5) cells/200μL.The white blood cell count and the levels of,plasma cytokines,BM mRNA,and BM surface markers were compared between the three groups.Human BM-derived CD34+hematopoietic progenitor cells were co-cultured with human ADSCs(hADSCs)or incubated in the presence of hADSCs conditioned media to investigate the effect on human cells in vitro.RESULTS The survival rate of mice that received one transplant of mADSCs was higher than that of mice that received three transplants.Multiple transplantations of ADSCs delayed the repopulation of BM hematopoietic stem cells.Anti-inflammatory effects and M2 polarization by intraperitoneal ADSCs might suppress erythropoiesis and induce myelopoiesis in sub-lethally RT mice.CONCLUSION The results suggested that an optimal amount of MSCs could improve survival rates post-WBI.

Quercetin and Rutin Affect the Survival and Proliferation of Human Skin-Derived Multipotent Mesenchymal Stromal Cells

Flavonoids are phenolic compounds with biological and pharmacological properties, such as antioxidant and antiviral effects. In the present work, we evaluated the effect of the flavonoids quercetin and rutin in human SD-MSCs （skin-derived-multipotent mesenchymal stromal cells）. Cultured SD-MSCs were exposed to different concentrations of flavonoids （80 to 320 μM） for 2 days in vitro. Cell viability was assessed by MTT assay and cell proliferation by BrdU staining. Cell death was quantified by the analysis of picnotic nuclei. In this paper, we demonstrated for the first time that both quercetin and rutin affect the viability of SD-MSCs, although high concentrations of quercetin （320 μM） promoted increased values of picnoctic nuclei. Quercetin treatment increased cell proliferation and, in contrast, rutin in the same concentration decreased these values. Our results may aid the comprehension of flavonoids effect in SD-MSCs. However, a better understanding of the mechanisms involving flavonoids and SD-MSCs interactions are necessary.