Mesenchymal stromal cell-derived extracellular vesicles: novel approach in hematopoietic stem cell transplantation

Microvesicles and exosomes isolated from murine bone marrow-derived mesenchymal stromal cells primed with p38MAPK inhibitor differentially regulate hematopoietic stem cell function

The signaling mechanisms active within mesenchymal stromal cells (MSCs) influence the composition of microvesicles (MVs) and exosomes (Exos) secreted by them. Previously, we showed that priming MSCs with a p38 pharmacological inhibitor (pMSCs) rejuvenates them and improves their ability to promote ex vivo hematopoietic stem cell (HSC) expansion. This study examined whether pMSCs exerted HSC-supportive ability via MVs (pMVs) and Exos (pExos). Our findings demonstrate distinct regulation of HSC fate by pMVs and pExos. pMVs promoted the expansion of long-term HSCs (LT-HSCs), distinguished by their robust self-renewal capacity and superior engraftment ability. In contrast, pExos facilitated expansion of short-term HSCs (ST-HSCs) with high proliferative and differentiation potential. Infusing a combination of pMVs- and pExos-expanded HSCs as a composite graft resulted in significantly higher HSC engraftment, emphasizing the synergistic interaction between LT- and ST-HSC populations. Gene expression studies, functional and phenotypic experiments showed that pMVs regulate HSC quiescence via the Egr1/Cdkn1a axis, while pExos control HSC proliferation via the Nfya/Cdkn1a axis. These findings provide insights into the molecular mechanisms underlying the differential regulation of HSC function by pMVs and pExos. It also proposes a composite graft strategy of using pMVs and pExos as "MSC-derived biologics" for improving the HSC transplantation success.

Mesenchymal stem cells protect the integrity of the alveolar epithelial barrier through extracellular vesicles by inhibiting MAPK-mediated necroptosis

BACKGROUND

Alveolar‒capillary barrier disruption is a hallmark of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). The contribution of necroptosis to the compromised alveolar-barrier in ALI remains unclear. Mesenchymal stem cells (MSCs) may contribute to tissue repair in ALI and ARDS. Here we evaluated the efficacy and explored the molecular mechanisms of menstrual blood-derived endometrial stem cells (MenSCs) and MenSC-derived extracellular vesicles (MenSC-EVs) in ALI-induced alveolar epithelial barrier dysfunction.

METHODS

Human lung epithelial cells were stimulated with endotoxin and treated with MenSCs or MenSC-EVs, and their barrier properties were evaluated. Lipopolysaccharide (LPS)-injured mice were treated with MenSCs or MSC-EVs, and the degree of lung injury and the alveolar epithelial barrier of the lung tissue were assessed.

RESULTS

We found that MenSCs reduced lung injury and restored alveolar-barrier integrity in lung tissue. In vitro, MenSCs reduced paracellular permeability and restored barrier integrity in human lung epithelial cells. MenSC-EVs replicated all these MenSC-mediated changes. Mechanistic research revealed that MenSCs inhibited MAPK signaling and necroptosis. JNK inhibition SP600125, and ERK inhibition U0126 or inhibition of necroptosis with Nec-1 or GSK872 diminished the beneficial anti-epithelial barrier dysfunction effects of MenSCs or MenSC-EVs.

CONCLUSIONS

Our results suggest that human menstrual blood-derived endometrial stem cells mitigate lung injury and improve alveolar barrier properties by inhibiting MAPK-mediated necroptosis through extracellular vesicles, supporting the application of MenSCs or MenSC-derived extracellular vesicles to treat ALI or ARDS.

Idiopathic pulmonary fibrosis microenvironment: Novel mechanisms and research directions

Idiopathic Pulmonary Fibrosis (IPF) is a progressive interstitial lung disease marked by increasing dyspnea and respiratory failure. The underlying mechanisms remain poorly understood, given the complexity of its pathogenesis. This review investigates the microenvironment of IPF to identify novel mechanisms and therapeutic avenues. Studies have revealed that various cell types, including alveolar epithelial cells, fibroblasts, myofibroblasts, and immune cells, are integral to disease progression, engaging in cellular stress responses and inflammatory regulation via signaling pathways such as TGF-β, Wnt, mTOR, and ROS. Non-coding RNAs, particularly miRNAs, are critical in IPF and may serve as diagnostic and prognostic biomarkers. Regarding treatment, mesenchymal stem cells (MSCs) and their extracellular vesicles (EVs) or non-vesicular derivatives offer promise by modulating immune responses, enhancing tissue repair, and inhibiting fibrosis. Additionally, alterations in the lung microbiota are increasingly recognized as a contributing factor to IPF progression, offering fresh insights into potential treatments. Despite the encouraging results of MSC-based therapies, the precise mechanisms and clinical applications remain subjects of ongoing research. This review emphasizes the significance of the IPF microenvironment and highlights the need for further exploration to develop effective therapies that could enhance patient outcomes.

Characterization of Circulating Vesicles of Complicated and Uncomplicated Systemic Sclerosis Patients and Their Role in Vascular Dysfunction

Extracellular vesicles (EVs) could be involved in the onset of systemic sclerosis (SSc) through the modulation of vascular function. Anyway, available data are contradictory, and further investigation would be necessary to clarify this aspect. Here, we characterized circulating EVs isolated from SSc patients and evaluated their effects on human vascular endothelial cells (HUVECs) and smooth muscle cells. In EVs from 13 complicated and 27 uncomplicated SSc patients and five healthy controls (HCs), we analyzed the size, concentration, and surface marker expression. In addition, EVs were used to stimulate HUVECs, and we evaluated cell viability, mitochondrial membrane potential, and nitric oxide (NO) and mitochondrial reactive oxygen species (MitoROS) release. In smooth muscle cells, the effects of EVs on calcium movement were examined. The results showed that the EVs of SSc patients expressed markers of T-lymphocyte/platelet/endothelial cell origin and were larger and more concentrated than those from HCs. In addition, the EVs of SSc patients reduced cell viability and mitochondrial membrane potential and increased NO and MitoROS release in HUVECs and intracellular calcium in smooth muscle cells. In conclusion, we found a specific pattern for EVs isolated from SSc patients, which could have a pathogenic role through direct actions on endothelial and smooth muscle cells.

Global microRNA profiling of bone marrow-MSC derived extracellular vesicles identifies miRNAs associated with hematopoietic dysfunction in aplastic anemia

Recently, we have reported that extracellular vesicles (EVs) from the bone marrow mesenchymal stromal cells (BM-MSC) of aplastic anemia (AA) patients inhibit hematopoietic stem and progenitor cell (HSPC) proliferative and colony-forming ability and promote apoptosis. One mechanism by which AA BM-MSC EVs might contribute to these altered HSPC functions is through microRNAs (miRNAs) encapsulated in EVs. However, little is known about the role of BM-MSC EVs derived miRNAs in regulating HSPC functions in AA. Therefore, we performed miRNA profiling of EVs from BM-MSC of AA (n = 6) and normal controls (NC) (n = 6) to identify differentially expressed miRNAs. The Integrated DEseq2 analysis revealed 34 significantly altered mature miRNAs, targeting 235 differentially expressed HSPC genes in AA. Hub gene analysis revealed 10 HSPC genes such as IGF-1R, IGF2R, PAK1, PTPN1, etc., which are targeted by EV miRNAs and had an enrichment of chemokine, MAPK, NK cell-mediated cytotoxicity, Rap1, PI3k-Akt, mTOR signalling pathways which are associated with hematopoietic homeostasis. We further showed that miR-139-5p and its target, IGF-1R (hub-gene), might regulate HSPC proliferation and apoptosis, which may serve as potential therapeutic targets in AA. Overall, the study highlights that AA BM-MSC EV miRNAs could contribute to impaired HSPC functions in AA.

The role of the hematopoietic stem/progenitor cells-derived extracellular vesicles in hematopoiesis

Hematopoietic stem cells (HSCs) are tightly regulated by specific microenvironments called niches to produce an appropriate number of mature blood cell types. Self-renewal and differentiation are two hallmarks of hematopoietic stem and progenitor cells, and their balance is critical for proper functioning of blood and immune cells throughout life. In addition to cell-intrinsic regulation, extrinsic cues within the bone marrow niche and systemic factors also affect the fate of HSCs. Despite this, many paracrine and endocrine factors that influence the function of hematopoietic cells remain unknown. In hematological malignancies, malignant cells remodel their niche into a permissive environment to enhance the survival of leukemic cells. These events are accompanied by loss of normal hematopoiesis. It is well known that extracellular vehicles (EVs) mediate intracellular interactions under physiological and pathological conditions. In other words, EVs transfer biological information to surrounding cells and contribute not only to physiological functions but also to the pathogenesis of some diseases, such as cancers. Therefore, a better understanding of cell-to-cell interactions may lead to identification of potential therapeutic targets. Recent reports have suggested that EVs are evolutionarily conserved constitutive mediators that regulate hematopoiesis. Here, we focus on the emerging roles of EVs in normal and pathological conditions, particularly in hematological malignancies. Owing to the high abundance of EVs in biological fluids, their potential use as biomarkers and therapeutic tools is discussed.

Differential Expression of the hTERT Gene in Umbilical Cord-Derived Mesenchymal Stem Cells Cocultured with B Cell Precursor Leukemia Cell Microparticles or CD41+/CD61+ Platelet Microparticles

Several investigations are being done to increase the short lifetime of mesenchymal stem cells (MSCs). One of the crucial genes involved in the immortalization of MSCs, hTERT (human telomerase reverse transcriptase), is activated in most publications using viral-based techniques. In this work, we investigated the use of platelet-derived (PMPs) and B cell precursor leukemia-derived microparticles as a nonviral method to trigger and compare the expression of the hTERT gene in MSCs. MSCs were extracted from the umbilical cord for the current investigation and identified using a flow cytometry approach and an inverted microscope. The Nalm-6 cell line and platelet concentrate were used to isolate microparticles (MPs). MSCs and MPs were cocultured for 14 days at 25-, 50-, and 100 μg/ml concentrations. qRT-PCR was used to research the expression of the hTERT gene. SPSS 26.0's t test was used to compare the outcomes. After coculture with platelet MPs, MSCs had higher levels of hTERT gene expression than the control group. In contrast, this gene's expression was concurrently decreased in MSCs exposed to MPs generated from Nalm-6. We demonstrated that following 14-day treatment, PMP significantly boosted the hTERT gene expression in MSCs, while the Nalm-6 MPs lowered the gene expression. However, additional studies are necessary due to the stability of hTERT gene expression and the immortalization of MSCs following exposure.

Extracellular vesicles as tools and targets in therapy for diseases

Extracellular vesicles (EVs) are nano-sized, membranous structures secreted into the extracellular space. They exhibit diverse sizes, contents, and surface markers and are ubiquitously released from cells under normal and pathological conditions. Human serum is a rich source of these EVs, though their isolation from serum proteins and non-EV lipid particles poses challenges. These vesicles transport various cellular components such as proteins, mRNAs, miRNAs, DNA, and lipids across distances, influencing numerous physiological and pathological events, including those within the tumor microenvironment (TME). Their pivotal roles in cellular communication make EVs promising candidates for therapeutic agents, drug delivery systems, and disease biomarkers. Especially in cancer diagnostics, EV detection can pave the way for early identification and offers potential as diagnostic biomarkers. Moreover, various EV subtypes are emerging as targeted drug delivery tools, highlighting their potential clinical significance. The need for non-invasive biomarkers to monitor biological processes for diagnostic and therapeutic purposes remains unfulfilled. Tapping into the unique composition of EVs could unlock advanced diagnostic and therapeutic avenues in the future. In this review, we discuss in detail the roles of EVs across various conditions, including cancers (encompassing head and neck, lung, gastric, breast, and hepatocellular carcinoma), neurodegenerative disorders, diabetes, viral infections, autoimmune and renal diseases, emphasizing the potential advancements in molecular diagnostics and drug delivery.

Adipose-Derived Mesenchymal Stem Cell Facilitate Hematopoietic Stem Cell Proliferation via the Jagged-1/Notch-1/Hes Signaling Pathway

Background

Poor graft function (PGF) is a life-threatening complication following hematopoietic stem cell transplantation (HSCT). Current therapies, such as CD34+ cell infusion, have shown limited effectiveness. Conversely, mesenchymal stem cells (MSCs) show potential in addressing PGF. Adipose-derived mesenchymal stem cells (ADSCs) effectively support long-term hematopoietic stem cell proliferation. Therefore, this study aimed to investigate the mechanisms underlying the long-term hematopoietic support provided by ADSCs.

Methods

ADSCs were isolated from mice and subsequently identified. In vitro experiments involved coculturing ADSCs as feeders with Lin-Sca-1+c-kit+ (LSK) cells from mice for 2 and 5 weeks. The number of LSK cells was quantified after coculture. Scanning electron microscopy was utilized to observe the interaction between ADSCs and LSK cells. Hes-1 expression was assessed using western blot and real-time quantitative PCR. An γ-secretase inhibitor (GSI) was used to confirm the involvement of the Jagged-1/Notch-1/Hes-1 pathway in LSK cell expansion. Additionally, Jagged-1 was knocked down in ADSCs to demonstrate its significance in ADSC-mediated hematopoietic support. In vivo experiments were conducted to study the hematopoietic support provided by ADSCs through the infusion of LSK, LSK + fibroblasts, and LSK + ADSCs, respectively. Mouse survival, platelet count, leukocyte count, and hemoglobin levels were monitored.

Results

ADSCs showed high-Jagged-1 expression and promoted LSK cell proliferation. There was a direct interaction between ADSCs and LSK cells. After coculture, Hes-1 expression increased in LSK cells. Moreover, GSI-reduced LSK cell proliferation and Hes-1 expression. Knockdown of Jagged-1 attenuated ADSCs-mediated promotion of LSK cell proliferation. Furthermore, ADSCs facilitated hematopoietic recovery and promoted the survival of NOD/SCID mice.

Conclusion

The hematopoietic support provided by ADSCs both in vivo and in vitro may be mediated, at least in part, through the Jagged-1/Notch-1 signaling pathway. These findings provide valuable insights into the mechanisms underlying ADSCs-mediated hematopoietic support and may have implications for improving the treatment of PGF following HSCT.

Progress in research on mesenchymal stem cells and their extracellular vesicles for treating fibrosis in systemic sclerosis

Systemic sclerosis (SSc) refers to an autoimmune disease characterized by immune dysfunction, vascular endothelial damage, and multi-organ fibrosis. Thus far, this disease is incurable, and its high mortality rate is significantly correlated with fibrotic events. Fibrosis has been confirmed as a difficult clinical treatment area that should be urgently treated in clinical medicine. Mesenchymal stem cells (MSCs) exhibit immunomodulatory, pro-angiogenic, and anti-fibrotic functions. MSCs-derived extracellular vesicles (EVs) have aroused rising interest as a cellular component that retains the functions of MSCs while circumventing the possible adverse effects of MSCs. Moreover, EVs have great potential in treating SSc. In this study, the current research progress on MSCs and their EVs for treating fibrosis in SSc was reviewed, with an aim to provide some reference for future MSCs and their EVs in treating SSc.

The miRNA Content of Bone Marrow-Derived Extracellular Vesicles Contributes to Protein Pathway Alterations Involved in Ionising Radiation-Induced Bystander Responses

Extracellular vesicles (EVs), through their cargo, are important mediators of bystander responses in the irradiated bone marrow (BM). MiRNAs carried by EVs can potentially alter cellular pathways in EV-recipient cells by regulating their protein content. Using the CBA/Ca mouse model, we characterised the miRNA content of BM-derived EVs from mice irradiated with 0.1 Gy or 3 Gy using an nCounter analysis system. We also analysed proteomic changes in BM cells either directly irradiated or treated with EVs derived from the BM of irradiated mice. Our aim was to identify key cellular processes in the EV-acceptor cells regulated by miRNAs. The irradiation of BM cells with 0.1 Gy led to protein alterations involved in oxidative stress and immune and inflammatory processes. Oxidative stress-related pathways were also present in BM cells treated with EVs isolated from 0.1 Gy-irradiated mice, indicating the propagation of oxidative stress in a bystander manner. The irradiation of BM cells with 3 Gy led to protein pathway alterations involved in the DNA damage response, metabolism, cell death and immune and inflammatory processes. The majority of these pathways were also altered in BM cells treated with EVs from mice irradiated with 3 Gy. Certain pathways (cell cycle, acute and chronic myeloid leukaemia) regulated by miRNAs differentially expressed in EVs isolated from mice irradiated with 3 Gy overlapped with protein pathway alterations in BM cells treated with 3 Gy EVs. Six miRNAs were involved in these common pathways interacting with 11 proteins, suggesting the involvement of miRNAs in the EV-mediated bystander processes. In conclusion, we characterised proteomic changes in directly irradiated and EV-treated BM cells, identified processes transmitted in a bystander manner and suggested miRNA and protein candidates potentially involved in the regulation of these bystander processes.

Bone marrow-derived extracellular vesicles carry the TGF-β signal transducer Smad2 to preserve hematopoietic stem cells in mice

Extracellular vesicles (EVs) released by cells in the bone marrow (BM) are important for regulating proliferation, differentiation, and other processes in hematopoietic stem cells (HSC). TGF-β signaling is now well known to be involved in HSC's quiescence and maintenance, but the TGF-β pathway related to EVs is still largely unknown in the hematopoietic system. We found that the EV inhibitor Calpeptin, when injected intravenously into mice, particularly affected the in vivo production of EVs carrying phosphorylated Smad2 (p-Smad2) in mouse BM. This was accompanied with an alteration in the quiescence and maintenance of murine HSC in vivo. EVs produced by murine mesenchymal stromal MS-5 cells also showed presence of p-Smad2 as a cargo. We treated MS-5 cells with the TGF-β inhibitor SB431542 in order to produce EVs lacking p-Smad2, and discovered that its presence was required for ex vivo maintenance of HSC. In conclusion, we revealed a new mechanism involving EVs produced in the mouse BM that transport bioactive phosphorylated Smad2 as a cargo to enhance the TGF-β signaling-mediated quiescence and maintenance of HSC.

Recent advances in engineering hydrogels for niche biomimicking and hematopoietic stem cell culturing

Hematopoietic stem cells (HSCs) provide a life-long supply of haemopoietic cells and are indispensable for clinical transplantation in the treatment of malignant hematological diseases. Clinical applications require vast quantities of HSCs with maintained stemness characteristics. Meeting this demand poses often insurmountable challenges for traditional culture methods. Creating a supportive artificial microenvironment for the culture of HSCs, which allows the expansion of the cells while maintaining their stemness, is becoming a new solution for the provision of these rare multipotent HSCs. Hydrogels with good biocompatibility, excellent hydrophilicity, tunable biochemical and biophysical properties have been applied in mimicking the hematopoietic niche for the efficient expansion of HSCs. This review focuses on recent progress in the use of hydrogels in this specialized application. Advanced biomimetic strategies use for the creation of an artificial haemopoietic niche are discussed, advances in combined use of hydrogel matrices and microfluidics, including the emerging organ-on-a-chip technology, are summarized. We also provide a brief description of novel stimulus-responsive hydrogels that are used to establish an intelligent dynamic cell microenvironment. Finally, current challenges and future perspectives of engineering hydrogels for HSC biomedicine are explored.