Paracrine Mechanisms of Mesenchymal Stromal Cells in Angiogenesis

Mesenchymal Stem Cell-Derived Extracellular Vesicles Protect Rat Nucleus Pulposus Cells from Oxidative Stress

BACKGROUND

Oxidative stress (OS) is mainly associated with the pathogenesis of intervertebral disc (IVD) degeneration; it causes nucleus pulposus cells (NPCs) to undergo senescence and triggers autophagy and apoptosis. This study aims to evaluate the regeneration potential of extracellular vesicles (EVs) derived from human umbilical cord-mesenchymal stem cells (hUC-MSCs) in an in vitro rat NPC-induced OS model.

DESIGN

NPCs were isolated from rat coccygeal discs, propagated, and characterized. OS was induced by hydrogen peroxide (H2O2), which is confirmed by 2,7-dichlorofluorescein diacetate (H2DCFDA) assay. EVs were isolated from hUC-MSCs and characterized by analyzing the vesicles using fluorescence microscope, scanning electron microscope (SEM), atomic force microscope (AFM), dynamic light scattering (DLS), and Western blot (WB). The in vitro effects of EVs on migration, uptake, and survival of NPCs were determined.

RESULTS

SEM and AFM topographic images revealed the size distribution of EVs. The phenotypes of isolated EVs showed that the size of EVs was 403.3 ± 85.94 nm, and the zeta potential was -0.270 ± 4.02 mV. Protein expression analysis showed that EVs were positive for CD81 and annexin V. Treatment of NPCs with EVs reduced H2O2-induced OS as evidenced by a decrease in reactive oxygen species (ROS) levels. Co-culture of NPCs with DiI-labeled EVs showed the cellular internalization of EVs. In the scratch assay, EVs significantly increased NPC proliferation and migration toward the scratched area. Quantitative polymerase chain reaction analysis showed that EVs significantly reduced the expression of OS genes.

CONCLUSION

EVs protected NPCs from H2O2-induced OS by reducing intracellular ROS generation and improved NPC proliferation and migration.

Locally injected bone marrow-derived mesenchymal stem cells reverts the histopathological changes in the tongue of carbimazole-induced hypothyroidism of male rats

OBJECTIVE

To decipher the role of locally injected bone marrow mesenchymal stem cells (BM-MSCs) in the tongue of hypothyroid rats.

DESIGN

A total 24 male Wister rats were utilized and allocated into 3 groups (n = 8). As for the control group, rats received distilled water via oral gavage. In the hypothyroid group, rats administered carbimazole 5 mg/ 250 g/ day for 6 successive weeks, for hypothyroidism induction. The BM-MSC treated hypothyroid group (BM-MSC group); hypothyroid rats received local injection of 0.5 million BM-MSCs in tongue. Six weeks after BM-MSC injection, tongue samples were processed for Hematoxylin and eosin (H and E) staining, Ki67-immunohistochemistry and histomorphometric analysis.

RESULTS

The hypothyroid group revealed degenerative alterations in the lingual papillae, and apparent thinning of the inferior lingual epithelium compared to their controls. Tongues of the BM-MSC group depicted restoration of the normal tongue histology. The Ki67 immunoreaction was apparently decreased in the lingual epithelium of hypothyroid group compared to their controls, however the BM-MSC group regained Ki67 immunostaining.

CONCLUSION

Our data suggest that administration of BM-MSCs rescued the degenerative changes in the lingual mucosa and one of the possible underlying mechanisms could be the restoration of cellular proliferation in the lingual epithelium.

Mesenchymal stem cells biological and biotechnological advances: Implications for clinical applications

BACKGROUND

Mesenchymal stem cells (MSCs) are multipotent stem cells that are able to differentiate into multiple lineages including bone, cartilage, muscle and fat. They hold immunomodulatory properties and therapeutic ability to treat multiple diseases, including autoimmune and chronic degenerative diseases. In this article, we reviewed the different biological properties, applications and clinical trials of MSCs. Also, we discussed the basics of manufacturing conditions, quality control, and challenges facing MSCs in the clinical setting.

METHODS

Extensive review of the literature was conducted through the databases PubMed, Google Scholar, and Cochrane. Papers published since 2015 and covering the clinical applications and research of MSC therapy were considered. Furthermore, older papers were considered when referring to pioneering studies in the field.

RESULTS

The most widely studied stem cells in cell therapy and tissue repair are bone marrow-derived mesenchymal stem cells. Adipose tissue-derived stem cells became more common and to a lesser extent other stem cell sources e.g., foreskin derived MSCs. MSCs therapy were also studied in the setting of COVID-19 infections, ischemic strokes, autoimmune diseases, tumor development and graft rejection. Multiple obstacles, still face the standardization and optimization of MSC therapy such as the survival and the immunophenotype and the efficiency of transplanted cells. MSCs used in clinical settings displayed heterogeneity in their function despite their extraction from healthy donors and expression of similar surface markers.

CONCLUSION

Mesenchymal stem cells offer a rising therapeutic promise in various diseases. However, their potential use in clinical applications requires further investigation.

Challenges of therapeutic applications and regenerative capacities of urine based stem cells in oral, and maxillofacial reconstruction

Urine-derived stem cells (USCs) have gained the attention of researchers in the biomedical field in the past few years . Regarding the several varieties of cells that have been used for this purpose, USCs have demonstrated mesenchymal stem cell-like properties, such as differentiation and immunomodulation. Furthermore, they could be differentiated into several lineages. This is very interesting for regenerative techniques based on cell therapy. This review will embark on describing their separation, and profiling. We will specifically describe the USCs characteristics, in addition to their differentiation potential. Then, we will introduce and explore the primary uses of USCs. These involve thier utilization as a platform to produce stem cells, however, we shall concentrate on the utilization of USCs for therapeutic, and regenerative orofacial applications, providing an in-depth evaluation of this purpose. The final portion will address the limitations and challenges of their implementation in regenerative dentistry.

Manufacturing mesenchymal stromal cells in a microcarrier-microbioreactor platform can enhance cell yield and quality attributes: case study for acute respiratory distress syndrome

Mesenchymal stem and stromal cells (MSCs) hold potential to treat a broad range of clinical indications, but clinical translation has been limited to date due in part to challenges with batch-to-batch reproducibility of potential critical quality attributes (pCQAs) that can predict potency/efficacy. Here, we designed and implemented a microcarrier-microbioreactor approach to cell therapy manufacturing, specific to anchorage-dependent cells such as MSCs. We sought to assess whether increased control of the biochemical and biophysical environment had the potential to create product with consistent presentation and elevated expression of pCQAs relative to established manufacturing approaches in tissue culture polystyrene (TCPS) flasks. First, we evaluated total cell yield harvested from dissolvable, gelatin microcarriers within a microbioreactor cassette (Mobius Breez) or a flask control with matched initial cell seeding density and culture duration. Next, we identified 24 genes implicated in a therapeutic role for a specific motivating indication, acute respiratory distress syndrome (ARDS); expression of these genes served as our pCQAs for initial in vitro evaluation of product potency. We evaluated mRNA expression for three distinct donors to assess inter-donor repeatability, as well as for one donor in three distinct batches to assess within-donor, inter-batch variability. Finally, we assessed gene expression at the protein level for a subset of the panel to confirm successful translation. Our results indicated that MSCs expanded with this microcarrier-microbioreactor approach exhibited reasonable donor-to-donor repeatability and reliable batch-to-batch reproducibility of pCQAs. Interestingly, the baseline conditions of this microcarrier-microbioreactor approach also significantly improved expression of several key pCQAs at the gene and protein expression levels and reduced total media consumption relative to TCPS culture. This proof-of-concept study illustrates key benefits of this approach to therapeutic cell process development for MSCs and other anchorage-dependent cells that are candidates for cell therapies.

Mesenchymal Stem Cell Spheroids: A Promising Tool for Vascularized Tissue Regeneration

BACKGROUND

Mesenchymal stem cells (MSCs) are undifferentiated cells that can differentiate into specific cell lineages when exposed to the right conditions. The ability of MSCs to differentiate into particular cells is considered very important in biological research and clinical applications. MSC spheroids are clusters of MSCs cultured in three dimensions, which play an important role in enhancing the proliferation and differentiation of MSCs. MSCs can also participate in vascular formation by differentiating into endothelial cells and secreting paracrine factors. Vascularization ability is essential in impaired tissue repair and function recovery. Therefore, the vascularization ability of MSCs, which enhances angiogenesis and accelerates tissue healing has made MSCs a promising tool for tissue regeneration. However, MSC spheroids are a relatively new research field, and more research is needed to understand their full potential.

METHODS

In this review, we highlight the importance of MSC spheroids' vascularization ability in tissue engineering and regenerative medicine while providing the current status of studies on the MSC spheroids' vascularization and suggesting potential future research directions for MSC spheroids.

RESULTS

Studies both in vivo and in vitro have demonstrated MSC spheroids' capacity to develop into endothelial cells and stimulate vasculogenesis.

CONCLUSION

MSC spheroids show potential to enhance vascularization ability in tissue regeneration. Yet, further research is required to comprehensively understand the relationship between MSC spheroids and vascularization mechanisms.

Functional variation among mesenchymal stem cells derived from different tissue sources

Background

Mesenchymal stem cells (MSCs) are increasingly recognized for their regenerative potential. However, their clinical application is hindered by their inherent variability, which is influenced by various factors, such as the tissue source, culture conditions, and passage number.

Methods

MSCs were sourced from clinically relevant tissues, including adipose tissue-derived MSCs (ADMSCs, n = 2), chorionic villi-derived MSCs (CMMSCs, n = 2), amniotic membrane-derived MSCs (AMMSCs, n = 3), and umbilical cord-derived MSCs (UCMSCs, n = 3). Passages included the umbilical cord at P0 (UCMSCP0, n = 2), P3 (UCMSCP3, n = 2), and P5 (UCMSCP5, n = 2) as well as the umbilical cord at P5 cultured under low-oxygen conditions (UCMSCP5L, n = 2).

Results

We observed that MSCs from different tissue origins clustered into six distinct functional subpopulations, each with varying proportions. Notably, ADMSCs exhibited a higher proportion of subpopulations associated with vascular regeneration, suggesting that they are beneficial for applications in vascular regeneration. Additionally, CMMSCs had a high proportion of subpopulations associated with reproductive processes. UCMSCP5 and UCMSCP5L had higher proportions of subpopulations related to female reproductive function than those for earlier passages. Furthermore, UCMSCP5L, cultured under low-oxygen (hypoxic) conditions, had a high proportion of subpopulations associated with pro-angiogenic characteristics, with implications for optimizing vascular regeneration.

Conclusions

This study revealed variation in the distribution of MSC subpopulations among different tissue sources, passages, and culture conditions, including differences in functions related to vascular and reproductive system regeneration. These findings hold promise for personalized regenerative medicine and may lead to more effective clinical treatments across a spectrum of medical conditions.

Differentiation of mesenchymal stem cells into vascular endothelial cells in 3D culture: a mini review

Mesenchymal Stem Cells, mesodermal origin and multipotent stem cells, have ability to differentiate into vascular endothelial cells. The cells are squamous in morphology, inlining, and protecting blood vessel tissue, as well as maintaining homeostatic conditions. ECs are essential in vascularization and blood vessels formation. The differentiation process, generally carried out in 2D culture systems, were relied on growth factors induction. Therefore, an artificial extracellular matrix with relevant mechanical properties is essential to build 3D culture models. Various 3D fabrication techniques, such as hydrogel-based and fibrous scaffolds, scaffold-free, and co-culture to endothelial cells were reviewed and summarized to gain insights. The obtained MSCs-derived ECs are shown by the expression of endothelial gene markers and tubule-like structure. In order to mimicking relevant vascular tissue, 3D-bioprinting facilitates to form more complex microstructures. In addition, a microfluidic chip with adequate flow rate allows medium perfusion, providing mechanical cues like shear stress to the artificial vascular vessels.

How long does the biological effect of a red light-emitting diode last on adipose-derived mesenchymal stem cells?

This research investigated the duration of the influence of red light-emitting diodes (LED, 630 nm; output power: 2452.5 mW; laser beam: 163.5 cm2; irradiance: 15 mW/cm2; radiant exposure: 4 J/cm2) on different periods after irradiation (6, 12, 24, 48, and 72 h) on adipose-derived mesenchymal stem cells' (AdMSCs) metabolism and paracrine factors. AdMSCs were irradiated three times every 48 h. Twenty-four hours after the last irradiation, there was a higher MTT absorbance, followed by a decrease after 48 h. The cells' secretome showed increased levels of IL-6 and VEGF after 12 and 24 h, but this was reversed after 48 h. Additionally, LED irradiation resulted in higher levels of nitrite and did not affect oxidative stress markers. LED irradiation had significant effects on AdMSCs after 24 h compared to other groups and its control group.

Proteomic analysis and functional validation reveal distinct therapeutic capabilities related to priming of mesenchymal stromal/stem cells with IFN-γ and hypoxia: potential implications for their clinical use

Mesenchymal stromal/stem cells (MSCs) are a heterogeneous population of multipotent cells that can be obtained from various tissues, such as dental pulp, adipose tissue, bone marrow and placenta. MSCs have gained importance in the field of regenerative medicine because of their promising role in cell therapy and their regulatory abilities in tissue repair and regeneration. However, a better characterization of these cells and their products is necessary to further potentiate their clinical application. In this study, we used unbiased high-resolution mass spectrometry-based proteomic analysis to investigate the impact of distinct priming strategies, such as hypoxia and IFN-γ treatment, on the composition and therapeutic functionality of the secretome produced by MSCs derived from the amniotic membrane of the human placenta (hAMSCs). Our investigation revealed that both types of priming improved the therapeutic efficacy of hAMSCs, and these improvements were related to the secretion of functional factors present in the conditioned medium (CM) and exosomes (EXOs), which play crucial roles in mediating the paracrine effects of MSCs. In particular, hypoxia was able to induce a pro-angiogenic, innate immune response-activating, and tissue-regenerative hAMSC phenotype, as highlighted by the elevated production of regulatory factors such as VEGFA, PDGFRB, ANGPTL4, ENG, GRO-γ, IL8, and GRO-α. IFN-γ priming, instead, led to an immunosuppressive profile in hAMSCs, as indicated by increased levels of TGFB1, ANXA1, THBS1, HOMER2, GRN, TOLLIP and MCP-1. Functional assays validated the increased angiogenic properties of hypoxic hAMSCs and the enhanced immunosuppressive activity of IFN-γ-treated hAMSCs. This study extends beyond the direct priming effects on hAMSCs, demonstrating that hypoxia and IFN-γ can influence the functional characteristics of hAMSC-derived secretomes, which, in turn, orchestrate the production of functional factors by peripheral blood cells. This research provides valuable insights into the optimization of MSC-based therapies by systematically assessing and comparing the priming type-specific functional features of hAMSCs. These findings highlight new strategies for enhancing the therapeutic efficacy of MSCs, particularly in the context of multifactorial diseases, paving the way for the use of hAMSC-derived products in clinical practice.

hTERT-Immortalized Mesenchymal Stem Cell-Derived Extracellular Vesicles: Large-Scale Manufacturing, Cargo Profiling, and Functional Effects in Retinal Epithelial Cells

As the economic burden associated with vision loss and ocular damage continues to rise, there is a need to explore novel treatment strategies. Extracellular vesicles (EVs) are enriched with various biological cargo, and there is abundant literature supporting the reparative and immunomodulatory properties of stem cell EVs across a broad range of pathologies. However, one area that requires further attention is the reparative effects of stem cell EVs in the context of ocular damage. Additionally, most of the literature focuses on EVs isolated from primary stem cells; the use of EVs isolated from human telomerase reverse transcriptase (hTERT)-immortalized stem cells has not been thoroughly examined. Using our large-scale EV-manufacturing platform, we reproducibly manufactured EVs from hTERT-immortalized mesenchymal stem cells (MSCs) and employed various methods to characterize and profile their associated cargo. We also utilized well-established cell-based assays to compare the effects of these EVs on both healthy and damaged retinal pigment epithelial cells. To the best of our knowledge, this is the first study to establish proof of concept for reproducible, large-scale manufacturing of hTERT-immortalized MSC EVs and to investigate their potential reparative properties against damaged retinal cells. The results from our studies confirm that hTERT-immortalized MSC EVs exert reparative effects in vitro that are similar to those observed in primary MSC EVs. Therefore, hTERT-immortalized MSCs may represent a more consistent and reproducible platform than primary MSCs for generating EVs with therapeutic potential.

Influence of Human Bone Marrow Mesenchymal Stem Cells Secretome from Acute Myeloid Leukemia Patients on the Proliferation and Death of K562 and K562-Lucena Leukemia Cell Lineages

Leukemias are among the most prevalent types of cancer worldwide. Bone marrow mesenchymal stem cells (MSCs) participate in the development of a suitable niche for hematopoietic stem cells, and are involved in the development of diseases such as leukemias, to a yet unknown extent. Here we described the effect of secretome of bone marrow MSCs obtained from healthy donors and from patients with acute myeloid leukemia (AML) on leukemic cell lineages, sensitive (K562) or resistant (K562-Lucena) to chemotherapy drugs. Cell proliferation, viability and death were evaluated, together with cell cycle, cytokine production and gene expression of ABC transporters and cyclins. The secretome of healthy MSCs decreased proliferation and viability of both K562 and K562-Lucena cells; moreover, an increase in apoptosis and necrosis rates was observed, together with the activation of caspase 3/7, cell cycle arrest in G0/G1 phase and changes in expression of several ABC proteins and cyclins D1 and D2. These effects were not observed using the secretome of MSCs derived from AML patients. In conclusion, the secretome of healthy MSCs have the capacity to inhibit the development of leukemia cells, at least in the studied conditions. However, MSCs from AML patients seem to have lost this capacity, and could therefore contribute to the development of leukemia.

The Effect of Cell Culture Passage on the Efficacy of Mesenchymal Stromal Cells as a Cell Therapy Treatment

Background/Objective: Mesenchymal Stromal Cells (MSCs) have been considered a promising treatment for several diseases, such as cardiac injuries. Many studies have analyzed their functional properties; however, few studies have characterized MSCs through successive culture passages. The main objective of this work was to analyze the phenotype and functionality of MSCs isolated from two different sources in five culture passages to determine if the culture passage might influence the efficacy of MSCs as a cell therapy treatment. Methods: Bone Marrow (BM)-MSCs were harvested from the femur of Wistar rats (n = 17) and Adipose Tissue(AT)-MSCs were isolated from inguinal fat (n = 17). MSCs were cultured for five culture passages, and the immunophenotype was analyzed by flow cytometry, the functionality was characterized by adipogenic, osteogenic, and chondrogenic differentiation assays, and cytokine secretion capacity was determined through the quantification of the Vascular Endothelial Growth-Factor, Fibroblast Growth-Factor2, and Transforming Growth-Factorβ1 in the cell supernatant. The ultrastructure of MSCs was analyzed by transmission electron microscopy. Results: BM-MSCs exhibited typical phenotypes in culture passages two, four, and five, and their differentiation capacity showed an irregular profile throughout the five culture passages analyzed. AT-MSCs showed a normal phenotype and differentiation capacity in all the culture passages. BM- and AT-MSCs did not modify their secretion ability or ultrastructural morphology. Conclusions: Throughout the culture passages, BM-MSCs, but not AT-MSCs, exhibited changes in their functional and phenotypic characteristic that might affect their efficacy as a cell therapy treatment. Therefore, the culture passage selected should be considered for the application of MSCs as a cell therapy treatment.

Unveiling the Potential of Extracellular Vesicles as Biomarkers and Therapeutic Nanotools for Gastrointestinal Diseases

Extracellular vesicles (EVs), acting as inherent nanocarriers adept at transporting a range of different biological molecules such as proteins, lipids, and genetic material, exhibit diverse functions within the gastroenteric tract. In states of normal health, they participate in the upkeep of systemic and organ homeostasis. Conversely, in pathological conditions, they significantly contribute to the pathogenesis of gastrointestinal diseases (GIDs). Isolating EVs from patients' biofluids facilitates the discovery of new biomarkers that have the potential to offer a rapid, cost-effective, and non-invasive method for diagnosing and prognosing specific GIDs. Furthermore, EVs demonstrate considerable therapeutic potential as naturally targeted physiological carriers for the intercellular delivery of therapeutic cargo molecules or as nanoscale tools engineered specifically to regulate physio-pathological conditions or disease progression. Their attributes including safety, high permeability, stability, biocompatibility, low immunogenicity, and homing/tropism capabilities contribute to their promising clinical therapeutic applications. This review will delve into various examples of EVs serving as biomarkers or nanocarriers for therapeutic cargo in the context of GIDs, highlighting their clinical potential for both functional and structural gastrointestinal conditions. The versatile and advantageous properties of EVs position them as promising candidates for innovative therapeutic strategies in advancing personalized medicine approaches tailored to the gastroenteric tract, addressing both functional and structural GIDs.

Advancing diabetes treatment: the role of mesenchymal stem cells in islet transplantation

Diabetes mellitus, a prevalent global health challenge, significantly impacts societal and economic well-being. Islet transplantation is increasingly recognized as a viable treatment for type 1 diabetes that aims to restore endogenous insulin production and mitigate complications associated with exogenous insulin dependence. We review the role of mesenchymal stem cells (MSCs) in enhancing the efficacy of islet transplantation. MSCs, characterized by their immunomodulatory properties and differentiation potential, are increasingly seen as valuable in enhancing islet graft survival, reducing immune-mediated rejection, and supporting angiogenesis and tissue repair. The utilization of MSC-derived extracellular vesicles further exemplifies innovative approaches to improve transplantation outcomes. However, challenges such as MSC heterogeneity and the optimization of therapeutic applications persist. Advanced methodologies, including artificial intelligence (AI) and single-cell RNA sequencing (scRNA-seq), are highlighted as potential technologies for addressing these challenges, potentially steering MSC therapy toward more effective, personalized treatment modalities for diabetes. This review revealed that MSCs are important for advancing diabetes treatment strategies, particularly through islet transplantation. This highlights the importance of MSCs in the field of regenerative medicine, acknowledging both their potential and the challenges that must be navigated to fully realize their therapeutic promise.

Human mesenchymal stem cell secretomes: Factors affecting profiling and challenges in clinical application

The promising field of regenerative medicine is thrilling as it can repair and restore organs for various debilitating diseases. Mesenchymal stem cells are one of the main components in regenerative medicine that work through the release of secretomes. By adopting the use of the secretome in cell-free-based therapy, we may be able to address the challenges faced in cell-based therapy. As one of the components of cell-free-based therapy, secretome has the advantage of a better safety and efficacy profile than mesenchymal stem cells. However, secretome has its challenges that need to be addressed, such as its bioprocessing methods that may impact the secretome content and its mechanisms of action in clinical settings. Effective and standardization of bioprocessing protocols are important to ensure the supply and sustainability of secretomes for clinical applications. This may eventually impact its commercialization and marketability. In this review, the bioprocessing methods and their impacts on the secretome profile and treatment are discussed. This improves understanding of its fundamental aspects leading to potential clinical applications.

Mesenchymal stem cell transplantation in burn wound healing: uncovering the mechanisms of local regeneration and tissue repair

Burn injuries pose a significant healthcare burden worldwide, often leading to long-term disabilities and reduced quality of life. To explore the impacts of the transplantation of mesenchymal stem cells (MSCs) on the healing of burns and the levels of serum cytokines, 60 fully grown Sprague-Dawley rats were randomly divided into three groups (n = 20 each): group I (control), group II (burn induction), and group III (burn induction + bone marrow (BM)-MSC transplantation). Groups II and III were further divided into four subgroups (n = 5 each) based on euthanasia duration (7, 14, 21, and 28 days post transplant). The experiment concluded with an anesthesia overdose for rat death. After 7, 14, 21, and 28 days, the rats were assessed by clinical, laboratory, and histopathology investigations. The results revealed significant improvements in burn healing potentiality in the group treated with MSC. Furthermore, cytokine levels were measured, with significant increases in interleukin (IL)-6 and interferon alpha (IFN) observed, while IL-10 and transforming growth factor beta (TGF-β) decreased at 7 days and increased until 28 days post burn. Also, the group that underwent the experiment exhibited increased levels of pro-inflammatory cytokines and the anti-inflammatory cytokine IL-10 when compared to the control group. Histological assessments showed better re-epithelialization, neovascularization, and collagen deposition in the experimental group, suggesting that MSC transplantation in burn wounds may promote burn healing by modulating the immune response and promoting tissue regeneration.

FGF2/HGF priming facilitates adipose-derived stem cell-mediated bone formation in osteoporotic defects

Aims

The activity of adipose-derived stem cells (ADSCs) is susceptible to the physiological conditions of the donor. Therefore, employing ADSCs from donors of advanced age or with diseases for cell therapy necessitates a strategy to enhance therapeutic efficacy before transplantation. This study aims to investigate the impact of supplementing Fibroblast Growth Factor 2 (FGF2) and Hepatocyte Growth Factor (HGF) on ADSC-mediated osteogenesis under osteoporotic conditions and to explore the underlying mechanisms of action.

Main methods

Adipose-derived stem cells (ADSCs) obtained from ovariectomized (OVX) rats were cultured ex vivo. These cells were cultured in an osteogenic medium supplemented with FGF2 and HGF and subsequently autologously transplanted into osteoporotic femur defects using Hydroxyapatite-Tricalcium Phosphate. The assessment of bone formation was conducted four weeks post-transplantation.

Key findings

Osteoporosis detrimentally affects the viability and osteogenic differentiation potential of ADSCs, often accompanied by a deficiency in FGF2 and HGF signaling. However, priming with FGF2 and HGF facilitated the formation of immature osteoblasts from OVX ADSCs in vitro, promoting the expression of osteoblastogenic proteins, including Runx-2, osterix, and ALP, during the early phase of osteogenesis. Furthermore, FGF2/HGF priming augmented the levels of VEGF and SDF-1α in the microenvironment of OVX ADSCs under osteogenic induction. Importantly, transplantation of OVX ADSCs primed with FGF2/HGF for 6 days significantly enhanced bone formation compared to non-primed cells. The success of bone regeneration was confirmed by the expression of type-1 collagen and osteocalcin in the bone tissue of the deficient area.

Significance

Our findings corroborate that priming with FGF2/HGF can improve the differentiation potential of ADSCs. This could be applied in autologous stem cell therapy for skeletal disease in the geriatric population.

The Role of Stem Cells as Therapeutics for Ischaemic Stroke

Stroke remains one of the leading causes of death and disability worldwide. Current reperfusion treatments for ischaemic stroke are limited due to their narrow therapeutic window in rescuing ischaemic penumbra. Stem cell therapy offers a promising alternative. As a regenerative medicine, stem cells offer a wider range of treatment strategies, including long-term intervention for chronic patients, through the reparation and replacement of injured cells via mechanisms of differentiation and proliferation. The purpose of this review is to evaluate the therapeutic role of stem cells for ischaemic stroke. This paper discusses the pathology during acute, subacute, and chronic phases of cerebral ischaemic injury, highlights the mechanisms involved in mesenchymal, endothelial, haematopoietic, and neural stem cell-mediated cerebrovascular regeneration, and evaluates the pre-clinical and clinical data concerning the safety and efficacy of stem cell-based treatments. The treatment of stroke patients with different types of stem cells appears to be safe and efficacious even at relatively higher concentrations irrespective of the route and timing of administration. The priming or pre-conditioning of cells prior to administration appears to help augment their therapeutic impact. However, larger patient cohorts and later-phase trials are required to consolidate these findings.

Increased Anti-Inflammatory Therapeutic Potential and Progenitor Marker Expression of Corneal Mesenchymal Stem Cells Cultured in an Optimized Propagation Medium

There is a huge unmet need for new treatment modalities for ocular surface inflammatory disorders (OSIDs) such as dry eye disease and meibomian gland dysfunction. Mesenchymal stem cell therapies may hold the answer due to their potent immunomodulatory properties, low immunogenicity, and ability to modulate both the innate and adaptive immune response. MSC-like cells that can be isolated from the corneal stroma (C-MSCs) offer a potential new treatment strategy; however, an optimized culture medium needs to be developed to produce the ideal phenotype for use in a cell therapy to treat OSIDs. The effects of in vitro expansion of human C-MSC in a medium of M199 containing fetal bovine serum (FBS) was compared to a stem cell medium (SCM) containing knockout serum replacement (KSR) with basic fibroblast growth factor (bFGF) and human leukemia inhibitory factor (LIF), investigating viability, protein, and gene expression. Isolating populations expressing CD34 or using siRNA knockdown of CD34 were investigated. Finally, the potential of C-MSC as a cell therapy was assessed using co-culture with an in vitro corneal epithelial cell injury model and the angiogenic effects of C-MSC conditioned medium were evaluated with blood and lymph endothelial cells. Both media supported proliferation of C-MSC, with SCM increasing expression of CD34, ABCG2, PAX6, NANOG, REX1, SOX2, and THY1, supported by increased associated protein expression. Isolating cell populations expressing CD34 protein made little difference to gene expression, however, knockdown of the CD34 gene led to decreased expression of progenitor genes. C-MSC increased viability of injured corneal epithelial cells whilst decreasing levels of cytotoxicity and interleukins-6 and -8. No pro-angiogenic effect of C-MSC was seen. Culture medium can significantly influence C-MSC phenotype and culture in SCM produced a cell phenotype more suitable for further consideration as an anti-inflammatory cell therapy. C-MSC show considerable potential for development as therapies for OSIDs, acting through anti-inflammatory action.

The role of Wnt signaling in mesenchymal stromal cell-driven angiogenesis

Development, growth, and remodeling of blood vessels occur through an intricate process involving cell differentiation, proliferation, and rearrangement by cell migration under the direction of various signaling pathways. Recent reports highlight that resident and exogenous mesenchymal stromal cells (MSCs) have the potential to regulate the neovascularization process through paracrine secretion of proangiogenic factors. Recent research has established that the vasculogenic potential of MSCs is regulated by several signaling pathways, including the Wnt signaling pathway, and their interplay. These findings emphasize the complex nature of the vasculogenic process and underscore the importance of understanding the underlying molecular mechanisms for the development of effective cell-based therapies in regenerative medicine. This review provides an updated briefing on the canonical and non-canonical Wnt signaling pathways and summarizes the recent reports of both in vitro and in vivo studies with the involvement of MSCs of various sources in the vasculogenic process mediated by Wnt signaling pathways. Here we outline the current understanding of the plausible role of the Wnt signaling pathway, specifically in MSC-regulated angiogenesis.

Stem cell-derived paracrine factors by modulated reactive oxygen species to enhance cancer immunotherapy

Herein, we present an approach for manipulating paracrine factors and signaling pathways in adipose-derived stem cells (ADSCs) to achieve highly effective tumor immunotherapy. Our method involves precise control of reactive oxygen species concentration using the CD90-maleimide-pluronic F68-chlorin e6 conjugate (CPFC) to create ACPFC, which is then attached to ADSCs through the CD90 receptor-specific interaction. By regulating the irradiated laser power, ACPFC promotes signaling pathways such as cascade-3, VEGFR2, α2β1, C3AR1, CR1-4, and C5AR1, leading to the secretion of various inflammatory cytokines such as IFN-γ, TGF-β, and IL-6, while inhibiting AKT, ERK, NFkB, PAR1, and PAR3/4 signaling pathways to reduce the secretion of cell growth factors like TIMP-1, TIMP-2, VEGF, Ang-2, FGF-2, and HGF. When ACPFC is injected intravenously into a tumor animal model, it autonomously targets and accumulates at the tumor site, and upon laser irradiation, it generates various anti-inflammatory factors while reducing angiogenesis growth factors. The resulting antitumor response recruits CD3+CD8+ cytotoxic T cells and CD3+CD4+ helper T cells into the tumor and spleen, leading to highly effective melanoma and pancreatic tumor treatment in mice. Our technology for regulating stem cell paracrine factors holds significant promise for the treatment of various diseases.

Light-emitting Diode Can Enhance the Metabolism and Paracrine Action of Mesenchymal Stem Cells

This study investigated the influence of red light-emitting diodes (LED, 630 nm) on different irradiation parameters and the number of applications on mesenchymal stem cells derived from adipose tissue (AdMSCs) metabolism and paracrine factors. The AdMSCs were irradiated with a LEDbox device (output power: 2452.5 mW; laser beam: 163.5 cm2 ; irradiance: 15 mW cm-2 ) using radiant exposures of 0.5, 2, and 4 J cm-2 , respectively. AdMSCs were irradiated once or every 48 h up to three irradiations. All molecular analyses were performed 24 h after the last irradiation. LED did not induce changes in cell count, DNA damage, and oxidative stress. A significant repercussion of the LED has been noticed after three irradiations with 4 J cm-2 . AdMSCs had higher levels of IL-6, IGF-1, and NOx index. A higher ATP content and MMT/Resazurin assay were identified in AdMSCs irradiated three times with 4 J cm-2 . Mitochondrial basal respiration, maximal respiration and proton leak under metabolic stress were reduced by 0.5 and 2 J cm-2 irradiations. These data showed that three LED irradiations with 4 J cm-2 may be a suitable parameter for future AdMSCs therapy because of its improved metabolic activity, ATP content, and IL-6, IGF-1, and nitric oxide secretion.

Adipose stromal cells bioproducts as cell-free therapies: manufacturing and therapeutic dose determine in vitro functionality

BACKGROUND

Extracellular vesicles (EV) are considered a cell-free alternative to mesenchymal stromal cell (MSC) therapy. Numerous reports describe the efficacy of EV in conferring immunomodulation and promoting angiogenesis, yet others report these activities to be conveyed in EV-free bioproducts. We hypothesized that this discrepancy may depend either on the method of isolation or rather the relative impact of the individual bioactive components within the MSC secretome.

METHODS

To answer this question, we performed an inter-laboratory study evaluating EV generated from adipose stromal cells (ASC) by either sequential ultracentrifugation (UC) or size-exclusion chromatography (SEC). The effect of both EV preparations on immunomodulation and angiogenesis in vitro was compared to that of the whole secretome and of the EV-free protein fraction after SEC isolation.

RESULTS

In the current study, neither the EV preparations, the secretome or the protein fraction were efficacious in inhibiting mitogen-driven T cell proliferation. However, EV generated by SEC stimulated macrophage phagocytic activity to a similar extent as the secretome. In turn, tube formation and wound healing were strongly promoted by the ASC secretome and protein fraction, but not by EV. Within the secretome/protein fraction, VEGF was identified as a potential driver of angiogenesis, and was absent in both EV preparations.

CONCLUSIONS

Our data indicate that the effects of ASC on immunomodulation and angiogenesis are EV-independent. Specific ASC-EV effects need to be dissected for their use as cell-free therapeutics.

Mesenchymal Stem Cell Extracellular Vesicles from Tissue-Mimetic System Enhance Epidermal Regeneration via Formation of Migratory Cell Sheets

BACKGROUND

The secretome of adipose-derived mesenchymal stem cells (ASCs) offers a unique approach to understanding and treating wounds, including the critical process of epidermal regeneration orchestrated by keratinocytes. However, 2D culture techniques drastically alter the secretory dynamics of ASCs, which has led to ambiguity in understanding which secreted compounds (e.g., growth factors, exosomes, reactive oxygen species) may be driving epithelialization.

METHODS

A novel tissue-mimetic 3D hydrogel system was utilized to enhance the retainment of a more regenerative ASC phenotype and highlight the functional secretome differences between 2D and 3D. Subsequently, the ASC-secretome was stratified by molecular weight and the presence/absence of extracellular vesicles (EVs). The ASC-secretome fractions were then evaluated to assess for the capacity to augment specific keratinocyte activities.

RESULTS

Culture of ASCs within the tissue-mimetic system enhanced protein secretion ~ 50%, exclusively coming from the > 100 kDa fraction. The ASC-secretome ability to modulate epithelialization functions, including migration, proliferation, differentiation, and morphology, resided within the "> 100 kDa" fraction, with the 3D ASC-secretome providing the greatest improvement. 3D ASC EV secretion was enhanced two-fold and exhibited dose-dependent effects on epidermal regeneration. Notably, ASC-EVs induced morphological changes in keratinocytes reminiscent of native regeneration, including formation of stratified cell sheets. However, only 3D-EVs promoted collective cell sheet migration and an epithelial-to-mesenchymal-like transition in keratinocytes, whereas 2D-EVs contained an anti-migratory stimulus.

CONCLUSION

This study demonstrates how critical the culture environment is on influencing ASC-secretome regenerative capabilities. Additionally, the critical role of EVs in modulating epidermal regeneration is revealed and their translatability for future clinical therapies is discussed.

The pathological and therapeutically role of mesenchymal stem cell (MSC)-derived exosome in degenerative diseases; Particular focus on LncRNA and microRNA

By releasing exosomes, which create the ideal milieu for the resolution of inflammation, mesenchymal stem cells (MSCs) enhance tissue healing and have strong immunomodulatory capabilities. MSCs-derived exosome also can affect tumor progress by a myriad of mechanisms. Exosomes function as a cell-cell communication tool to affect cellular activity in recipient cells and include an array of efficient bioactive chemicals. Understanding the fundamental biology of inflammation ablation, tissue homeostasis, and the creation of therapeutic strategies is particularly interested in the horizontal transfer of exosomal long non-coding RNAs (lncRNA) and microRNAs (miRNAs) to recipient cells, where they affect target gene expression. Herein, we propose an exosomal lncRNA and microRNA profile in neurological, renal, cardiac, lung, and liver diseases as well as skin wounds and arthritis.

Enhanced bioprocess control to advance the manufacture of mesenchymal stromal cell-derived extracellular vesicles in stirred-tank bioreactors

Extracellular vesicles (EVs) derived from mesenchymal stromal cells (MSCs) act as signaling mediators of cellular responses. However, despite representing a promising alternative to cell-based therapies, clinical translation of EVs is currently limited by their lack of scalability and standardized bioprocessing. Herein, we integrated scalable downstream processing protocols with standardized expansion of large numbers of viable cells in stirred-tank bioreactors to improve EV production. Higher EV yields were linked to EV isolation by tangential flow filtration followed by size exclusion chromatography, rendering 5 times higher number of EVs comparatively to density gradient ultracentrifugation protocols. Additionally, when compared to static culture, EV manufacture in bioreactors resulted in 2.2 higher yields. Highlighting the role of operating under optimal cell culture conditions to maximize the number of EVs secreted per cell, MSCs cultured at lower glucose concentration favored EV secretion. While offline measurements of metabolites concentration can be performed, in this work, Raman spectroscopy was also applied to continuously track glucose levels in stirred-tank bioreactors, contributing to streamline the selection of optimal EV collection timepoints. Importantly, MSC-derived EVs retained their quality attributes and were able to stimulate angiogenesis in vitro, therefore highlighting their promising therapeutic potential.

Effect of stem cell secretome in skin rejuvenation: a narrative review

PURPOSE

Cutaneous aging is an inevitable biological process that develops over time due to cumulative cellular and molecular changes caused by exposure to intrinsic (chronological aging) and extrinsic (photo-aging) factors on the skin. Skin aging is characterized by a decline in the body's capability to sustain senescence, dermal cell apoptosis, and homeostasis. Stem cell secretions (secretome) are defined as the total set of dynamically overlapping paracrine soluble growth factors, cytokines, chemokines, angiogenic factors, extracellular matrix proteins, and antimicrobial peptides known to be responsible for tissue rejuvenation, regeneration, homeostasis, and immunomodulation.

METHODS

In this review, we summarized the molecular and regulatory mechanism of the secretome in preventing the skin aging process, as well as its capacity in inducing skin rejuvenation. Furthermore, we illustrated secretome efficiency as an anti-aging therapeutic strategy based on in vitro and in vivo published studies.

RESULTS

In all reviewed publications, the secretome has been proven to be the most effective treatment for aged skin, capable of reversing the aging process through the action of cytokines, growth factors, and collagen, which are its primary components. The reported mechanism of action involves modulating the signaling pathways of aging and replenishing the skin with collagen, fibronectin, and elastin, ultimately resulting in skin renewal and rejuvenation.

CONCLUSION

In conclusion, compared to available treatments, the secretome shows great promise as an anti-aging therapy.

Effects of Atrazine exposure on human bone marrow-derived mesenchymal stromal cells assessed by combinatorial assay matrix

Introduction

Mesenchymal Stromal/Stem cells (MSCs) are an essential component of the regenerative and immunoregulatory stem cell compartment of the human body and thus of major importance in human physiology. The MSCs elicit their beneficial properties through a multitude of complementary mechanisms, which makes it challenging to assess their phenotype and function in environmental toxicity screening. We here employed the novel combinatorial assays matrix approach/technology to profile the MSC response to the herbicide Atrazine, which is a common environmental xenobiotic, that is in widespread agricultural use in the US and other countries, but banned in the EU. Our here presented approach is representative for screening the impact of environmental xenobiotics and toxins on MSCs as an essential representative component of human physiology and well-being.

Methods

We here employed the combinatorial assay matrix approach, including a panel of well standardized assays, such as flow cytometry, multiplex secretome analysis, and metabolic assays, to define the phenotype and functionality of human-donor-derived primary MSCs exposed to the representative xenobiotic Atrazine. This assay matrix approach is now also endorsed for characterization of cell therapies by leading regulatory agencies, such as FDA and EMA.

Results

Our results show that the exposure to Atrazine modulates the metabolic activity, size, and granularity of MSCs in a dose and time dependent manner. Intriguingly, Atrazine exposure leads to a broad modulation of the MSCs secretome (both upregulation and downmodulation of certain factors) with the identification of Interleukin-8 as the topmost upregulated representative secretory molecule. Interestingly, Atrazine attenuates IFNγ-induced upregulation of MHC-class-II, but not MHC-class-I, and early phosphorylation signals on MSCs. Furthermore, Atrazine exposure attenuates IFNγ responsive secretome of MSCs. Mechanistic knockdown analysis identified that the Atrazine-induced effector molecule Interleukin-8 affects only certain but not all the related angiogenic secretome of MSCs.

Discussion

The here described Combinatorial Assay Matrix Technology identified that Atrazine affects both the innate/resting and cytokine-induced/stimulated assay matrix functionality of human MSCs, as identified through the modulation of selective, but not all effector molecules, thus vouching for the great usefulness of this approach to study the impact of xenobiotics on this important human cellular subset involved in the regenerative healing responses in humans.

Menstrual blood-derived mesenchymal stromal cells: impact of preconditioning on the cargo of extracellular vesicles as potential therapeutics

BACKGROUND

Mesenchymal stromal cells (MSCs) have been shown to exert their therapeutic effects through the secretion of broad spectrum of paracrine factors, including extracellular vesicles (EVs). Accordingly, EVs are being pursued as a promising alternative to cell-based therapies. Menstrual blood-derived stromal cells (MenSCs) are a type of MSC that, due to their immunomodulatory and regenerative properties, have emerged as an innovative source. Additionally, new strategies of cell priming may potentially alter the concentration and cargo of released EVs, leading to modification of their biological properties. In this study, we aimed to characterize the EVs released by MenSCs and compare their therapeutic potential under three different preconditioning conditions (proinflammatory stimuli, physioxia, and acute hypoxia).

METHODS

MenSCs were isolated from five healthy women. Following culturing to 80% confluence, MenSCs were exposed to different priming conditions: basal (21% O₂), proinflammatory stimuli (IFNγ and TNFα, 21% O₂), physioxia (1-2% O₂), and acute hypoxia (< 1% O₂) for 48-72 h. Conditioned media from MenSCs was collected after 48 h and EVs were isolated by a combination of ultra-filtration and differential centrifugation. An extensive characterization ranging from nano-flow cytometry (nFC) to quantitative high-throughput shotgun proteomics was performed. Bioinformatics analyses were used to derive hypotheses on their biological properties.

RESULTS

No differences in the morphology, size, or number of EVs released were detected between priming conditions. The proteome analysis associated with basal MenSC-EVs prominently revealed their immunomodulatory and regenerative capabilities. Furthermore, quantitative proteomic analysis of differentially produced MenSC-EVs provided sufficient evidence for the utility of the differential preconditioning in purpose-tailoring EVs for their therapeutic application: proinflammatory priming enhanced the anti-inflammatory, regenerative and immunomodulatory capacity in the innate response of EVs, physioxia priming also improves tissue regeneration, angiogenesis and their immunomodulatory capacity targeting on the adaptive response, while acute hypoxia priming, increased hemostasis and apoptotic processes regulation in MenSC-EVs, also by stimulating immunomodulation mainly through the adaptive response.

CONCLUSIONS

Priming of MenSCs under proinflammatory and hypoxic conditions affected the cargo proteome of EVs released, resulting in different therapeutic potential, and thus warrants experimental exploration with the aim to generate better-defined MSC-derived bioproducts.

Methylglyoxal Impairs the Pro-Angiogenic Ability of Mouse Adipose-Derived Stem Cells (mADSCs) via a Senescence-Associated Mechanism

Adipose-derived stem cells (ADSCs) play a crucial role in angiogenesis and repair of damaged tissues. However, in pathological conditions including diabetes, ADSC function is compromised. This work aims at evaluating the effect of Methylglyoxal (MGO), a product of chronic hyperglycemia, on mouse ADSCs' (mADSCs) pro-angiogenic function and the molecular mediators involved. The mADSCs were isolated from C57bl6 mice. MGO-adducts and p-p38 MAPK protein levels were evaluated by Western Blot. Human retinal endothelial cell (hREC) migration was analyzed by transwell assays. Gene expression was measured by qRT-PCR, and SA-βGal activity by cytofluorimetry. Soluble factor release was evaluated by multiplex assay. MGO treatment does not impair mADSC viability and induces MGO-adduct accumulation. hREC migration is reduced in response to both MGO-treated mADSCs and conditioned media from MGO-treated mADSCs, compared to untreated cells. This is associated with an increase of SA-βGal activity, SASP factor release and p53 and p21 expression, together with a VEGF- and PDGF-reduced release from MGO-treated mADSCs and a reduced p38-MAPK activation in hRECs. The MGO-induced impairment of mADSC function is reverted by senolytics. In conclusion, MGO impairs mADSCs' pro-angiogenic function through the induction of a senescent phenotype, associated with the reduced secretion of growth factors crucial for hREC migration.

Spheroids of adipose derived stem cells show their potential in differentiating towards the angiogenic lineage

INTRODUCTION

Adipose derived stem cells (ASCs) are a mesenchymal stem cell population of great scientific interest due to their abundance and easiness in obtaining them from adipose tissue. Recently, several techniques for three dimensional (3D) ASCs cultivation have been developed to obtain spheroids of adipose stem cells (SASCs). It was already proved that ASCs are able to differentiate towards the endothelial lineage thus, for the first time, we investigated the ability of our 3D SASCs to differentiate endothelially and the effects of not differentiated SASC secreted factors on specific cultured cells.

MATERIALS AND METHODS

SASCs were differentiated with a specific medium towards endothelial lineage. Cell viability, gene and protein expression of typical endothelial markers were analysed. Moreover, tube formation, wound healing and migration assays were performed to investigate the ability in migration and angiogenic networks formation of endothelially differentiated cells. SASCs secretome were also tested.

RESULTS

We showed the ability of SASCs to differentiate towards the endothelial lineage with an increase in cell viability of 15-fold and 8-fold at 14 and 21 days of differentiation respectively. Moreover, we showed the upregulation of VEGF-A and CD31 mRNAs of 9-fold and 1300-fold in SASCs endothelially differentiated cells, whilst protein expression was different. VEGF-A protein expression was upregulated whilst CD31 protein wasn't translated. In addition, ICAM1, VCAM1, ANGPT1, CD62E protein levels remain unchanged. SASCs were also able to organize themselves into angiogenic networks after 7 days of culturing themon ECMatrix. Secreted factors from undifferentiated 3D SASCs acted in a paracrine way on HUVECs and endothelially differentiated ASCs seeded on ECMatrix to promote angiogenic events.

CONCLUSIONS

SASCs, thanks to their multilineage differentiation potential, also possess the ability to differentiate towards endothelial lineage and to organize themselves into angiogenic networks. Moreover, they are able to promote angiogenesis through their secreted factors.

Single-Cell RNA-Seq Reveals LRRC75A-Expressing Cell Population Involved in VEGF Secretion of Multipotent Mesenchymal Stromal/Stem Cells Under Ischemia

Human multipotent mesenchymal stromal/stem cells (MSCs) have been utilized in cell therapy for various diseases and their clinical applications are expected to increase in the future. However, the variation in MSC-based product quality due to the MSC heterogeneity has resulted in significant constraints in the clinical utility of MSCs. Therefore, we hypothesized that it might be important to identify and ensure/enrich suitable cell subpopulations for therapies using MSC-based products. In this study, we aimed to identify functional cell subpopulations to predict the efficacy of angiogenic therapy using bone marrow-derived MSCs (BM-MSCs). To assess its angiogenic potency, we observed various levels of vascular endothelial growth factor (VEGF) secretion among 11 donor-derived BM-MSC lines under in vitro ischemic culture conditions. Next, by clarifying the heterogeneity of BM-MSCs using single-cell RNA-sequencing analysis, we identified a functional cell subpopulation that contributed to the overall VEGF production in BM-MSC lines under ischemic conditions. We also found that leucine-rich repeat-containing 75A (LRRC75A) was more highly expressed in this cell subpopulation than in the others. Importantly, knockdown of LRRC75A using small interfering RNA resulted in significant inhibition of VEGF secretion in ischemic BM-MSCs, indicating that LRRC75A regulates VEGF secretion under ischemic conditions. Therefore, LRRC75A may be a useful biomarker to identify cell subpopulations that contribute to the angiogenic effects of BM-MSCs. Our work provides evidence that a strategy based on single-cell transcriptome profiles is effective for identifying functional cell subpopulations in heterogeneous MSC-based products.

The Potential of MSC-Based Cell-Free Therapy in Wound Healing-A Thorough Literature Review

A wound is an interruption of the normal anatomic structure and function of the skin, which is critical in protecting against foreign pathogens, regulating body temperature and water balance. Wound healing is a complex process involving various phases, including coagulation, inflammation, angiogenesis, re-epithelialization, and re-modeling. Factors such as infection, ischemia, and chronic diseases such as diabetes can compromise wound healing, leading to chronic and refractory ulcers. Mesenchymal stem cells (MSCs) have been used to treat various wound models due to their paracrine activity (secretome) and extracellular vehicles (exosomes) that contain several molecules, including long non-coding RNAs (lncRNAs), micro-RNAs (miRNAs), proteins, and lipids. Studies have shown that MSCs-based cell-free therapy using secretome and exosomes has great potential in regenerative medicine compared to MSCs, as there are fewer safety concerns. This review provides an overview of the pathophysiology of cutaneous wounds and the potential of MSCs-based cell-free therapy in each phase of wound healing. It also discusses clinical studies of MSCs-based cell-free therapies.

Mesenchymal Stem Cell in Pancreatic Islet Transplantation

Pancreatic islet transplantation is a therapeutic option for achieving physiologic regulation of plasma glucose in Type 1 diabetic patients. At the same time, mesenchymal stem cells (MSCs) have demonstrated their potential in controlling graft rejection, the most fearsome complication in organ/tissue transplantation. MSCs can interact with innate and adaptive immune system cells either through direct cell-cell contact or through their secretome including exosomes. In this review, we discuss current findings regarding the graft microenvironment of pancreatic islet recipient patients and the crucial role of MSCs operation as cell managers able to control the immune system to prevent rejection and promote endogenous repair. We also discuss how challenging stressors, such as oxidative stress and impaired vasculogenesis, may jeopardize graft outcomes. In order to face these adverse conditions, we consider either hypoxia-exposure preconditioning of MSCs or human stem cells with angiogenic potential in organoids to overcome islets' lack of vasculature. Along with the shepherding of carbon nanotubes-loaded MSCs to the transplantation site by a magnetic field, these studies look forward to exploiting MSCs stemness and their immunomodulatory properties in pancreatic islet transplantation.

Impact of Canine Amniotic Mesenchymal Stem Cell Conditioned Media on the Wound Healing Process: In Vitro and In Vivo Study

The aim of this study was to provide a beneficial treatment effect of mesenchymal stem cell products derived from the canine amniotic membrane (AM-MSC) on the complicated wound healing process in dogs. AM-MSCs were characterized in terms of morphology, phenotypic profile, and multilineage differentiation potential. The in vitro study of the effect of canine amniotic mesenchymal stem cell conditioned media (AMMSC-CM) on a primary skin fibroblast cell culture scratch assay showed a decrease in the measured scratch area of about 66.39% against the negative control (Dulbecco's Modified Eagle's Medium-32.55%) and the positive control (Dulbecco's Modified Eagle's Medium supplemented with FGF2, N2, B27, and EGF-82.077%) after 72 h treatment. In the experimental study, seven dogs with complicated nonhealing wounds were treated with a combination of antibiotics, NSAIDs, and local AMMSC-CM application. After 15 days of therapy, we observed a 98.47% reduction in the wound surface area as opposed to 57.135% in the control group treated by conventional therapy based on debridement of necrotic tissue, antibiotic therapy, pain management, and change of wound dressing.

Harmonised culture procedures minimise but do not eliminate mesenchymal stromal cell donor and tissue variability in a decentralised multicentre manufacturing approach

BACKGROUND

Mesenchymal stromal cells (MSCs), commonly sourced from adipose tissue, bone marrow and umbilical cord, have been widely used in many medical conditions due to their therapeutic potential. Yet, the still limited understanding of the underlying mechanisms of action hampers clinical translation. Clinical potency can vary considerably depending on tissue source, donor attributes, but importantly, also culture conditions. Lack of standard procedures hinders inter-study comparability and delays the progression of the field. The aim of this study was A- to assess the impact on MSC characteristics when different laboratories, performed analysis on the same MSC material using harmonised culture conditions and B- to understand source-specific differences.

METHODS

Three independent institutions performed a head-to-head comparison of human-derived adipose (A-), bone marrow (BM-), and umbilical cord (UC-) MSCs using harmonised culture conditions. In each centre, cells from one specific tissue source were isolated and later distributed across the network to assess their biological properties, including cell expansion, immune phenotype, and tri-lineage differentiation (part A). To assess tissue-specific function, angiogenic and immunomodulatory properties and the in vivo biodistribution were compared in one expert lab (part B).

RESULTS

By implementing a harmonised manufacturing workflow, we obtained largely reproducible results across three independent laboratories in part A of our study. Unique growth patterns and differentiation potential were observed for each tissue source, with similar trends observed between centres. Immune phenotyping verified expression of typical MSC surface markers and absence of contaminating surface markers. Depending on the established protocols in the different laboratories, quantitative data varied slightly. Functional experiments in part B concluded that conditioned media from BM-MSCs significantly enhanced tubulogenesis and endothelial migration in vitro. In contrast, immunomodulatory studies reported superior immunosuppressive abilities for A-MSCs. Biodistribution studies in healthy mice showed lung entrapment after administration of all three types of MSCs, with a significantly faster clearance of BM-MSCs.

CONCLUSION

These results show the heterogeneous behaviour and regenerative properties of MSCs as a reflection of intrinsic tissue-origin properties while providing evidence that the use of harmonised culture procedures can reduce but do not eliminate inter-lab and operator differences.

Drug-based mobilisation of mesenchymal stem/stromal cells improves cardiac function post myocardial infarction

There is an unmet need for treatments that prevent the progressive cardiac dysfunction following myocardial infarction. Mesenchymal stem/stromal cells (MSCs) are under investigation for cardiac repair; however, culture expansion prior to transplantation is hindering their homing and reparative abilities. Pharmacological mobilisation could be an alternative to MSC transplantation. Here, we report that endogenous MSCs mobilise into the circulation at day 5 post myocardial infarction in male Lewis rats. This mobilisation can be significantly increased by using a combination of the FDA-approved drugs mirabegron (β3-adrenoceptor agonist) and AMD3100 (CXCR4 antagonist). Blinded cardiac magnetic resonance imaging analysis showed the treated group to have increased left ventricular ejection fraction and decreased end systolic volume at 5 weeks post myocardial infarction. The mobilised group had a significant decrease in plasma IL-6 and TNF-α levels, a decrease in interstitial fibrosis, and an increase in the border zone blood vessel density. Conditioned medium from blood-derived MSCs supported angiogenesis in vitro, as shown by tube formation and wound healing assays. Our data suggest a novel pharmacological strategy that enhances myocardial infarction-induced MSC mobilisation and improves cardiac function after myocardial infarction.

Progress and emerging techniques for biomaterial-based derivation of mesenchymal stem cells (MSCs) from pluripotent stem cells (PSCs)

The use of mesenchymal stem cells (MSCs) for clinical purposes has skyrocketed in the past decade. Their multilineage differentiation potentials and immunomodulatory properties have facilitated the discovery of therapies for various illnesses. MSCs can be isolated from infant and adult tissue sources, which means they are easily available. However, this raises concerns because of the heterogeneity among the various MSC sources, which limits their effective use. Variabilities arise from donor- and tissue-specific differences, such as age, sex, and tissue source. Moreover, adult-sourced MSCs have limited proliferation potentials, which hinders their long-term therapeutic efficacy. These limitations of adult MSCs have prompted researchers to develop a new method for generating MSCs. Pluripotent stem cells (PSCs), such as embryonic stem cells and induced PSCs (iPSCs), can differentiate into various types of cells. Herein, a thorough review of the characteristics, functions, and clinical importance of MSCs is presented. The existing sources of MSCs, including adult- and infant-based sources, are compared. The most recent techniques for deriving MSCs from iPSCs, with a focus on biomaterial-assisted methods in both two- and three-dimensional culture systems, are listed and elaborated. Finally, several opportunities to develop improved methods for efficiently producing MSCs with the aim of advancing their various clinical applications are described.

Safety and efficacy of mesenchymal stromal cell therapy for multi-drug-resistant acute and late-acute graft-versus-host disease following allogeneic hematopoietic stem cell transplantation

Graft versus host disease (GvHD) remains a significant risk for mortality and morbidity following allogeneic hematopoietic stem cell transplantation (HSCT). A growing literature supports successful applications of mesenchymal stromal cells (MSCs) for the treatment of steroid-refractory acute GvHD (aGvHD). However, there is limited knowledge about the effects of MSC treatment on late-acute GvHD (late aGvHD). In this article, we present our multicenter study on the safety and efficacy of MSC therapy for patients with steroid-refractory late aGvHD in comparison to those with aGvHD. The outcome measures include non-relapse mortality (NRM) and survival probability over a 2-year follow-up. The study includes a total of 76 patients with grades III-IV aGvHD (n = 46) or late aGvHD (n = 30), who had been treated with at least two lines of steroid-containing immunosuppressive therapy. Patients received weekly adipose or umbilical cord-derived MSC infusions at a dose of median 1.55 (ranging from 0.84 to 2.56) × 10⁶/kg in the aGvHD group, and 1.64 (ranging from 0.85 to 2.58) × 10⁶/kg in the late aGvHD group. This was an add-on treatment to ongoing conventional pharmaceutical management. In the aGvHD group, 23 patients received one or two infusions, 20 patients had 3-4, and three had ≥ 5. Likewise, in the late aGvHD group, 20 patients received one or two infusions, nine patients had 3-4, and one had ≥ 5. MSC was safe without acute or late adverse effects in 76 patients receiving over 190 infusions. In aGvHD group, 10.9% of the patients had a complete response (CR), 23.9% had a partial response (PR), and 65.2% had no response (NR). On the other hand, in the late aGvHD group, 23.3% of the patients had CR, 36.7% had PR, and the remaining 40% had NR. These findings were statistically significant (p = 0.031). Also, at the 2-year follow-up, the cumulative incidence of NRM was significantly lower in patients with late aGvHD than in patients with aGvHD at 40% (95% CI, 25-62%) versus 71% (95% CI, 59-86%), respectively (p = 0.032). In addition, the probability of survival at 2 years was significantly higher in patients with late aGvHD than in the aGvHD group at 59% (95% CI, 37-74%) versus 28% (95% CI, 13-40%), respectively (p = 0.002). To our knowledge, our study is the first to compare the safety and efficacy of MSC infusion(s) for the treatment of steroid-resistant late aGVHD and aGVHD. There were no infusion-related adverse effects in either group. The response rate to MSC therapy was significantly higher in the late aGvHD group than in the aGvHD group. In addition, at the 2-year follow-up, the survival and NRM rates were more favorable in patients with late aGVHD than in those with aGVHD. Thus, the results are encouraging and warrant further studies to optimize MSC-based treatment for late aGVHD.

Matrix Metalloproteinase 1 as a Marker of Tonsil-Derived Mesenchymal Stem Cells to Assess Bone Marrow Cell Migration

BACKGROUND

To achieve optimal bone marrow engraftment during bone marrow transplantation, migration of donor bone marrow cells (BMCs) toward the recipient's bone marrow is critical. Despite the enhanced engraftment of BMCs by co-administration of mesenchymal stem cells (MSCs), the efficiency can be variable depending on MSC donor. The purpose of this study is to examine the functional heterogeneity of tonsil-derived MSCs (TMSCs) and to identify a marker to evaluate efficacy for the enhancement of BMC migration.

METHODS

To examine the donor-to-donor variation of TMSCs in potentiating BMC migration, we isolated TMSCs from 25 independent donors. Transcriptome of TMSCs and proteome of conditioned medium derived from TMSC were analyzed.

RESULTS

Enhanced BMC migration by conditioned medium derived from TMSCs was variable depending on TMSC donor. The TMSCs derived from 25 donors showed distinct expression profiles compared with other cells, including fibroblasts, adipose-derived MSCs and bone marrow-derived MSCs. TMSCs were distributed in two categories: high- and low-efficacy groups for potentiating BMC migration. Transcriptome analysis of TMSCs and proteome profiles of conditioned medium derived from TMSCs revealed higher expression and secretion of matrix metalloproteinase (MMP) 1 in the high-efficacy group. MMP1 knockdown in TMSCs abrogated the supportive efficacy of conditioned medium derived from TMSC cultures in BMC migration.

CONCLUSION

These data suggest that secreted MMP1 can be used as a marker to evaluate the efficacy of TMSCs in enhancing BMC migration. Furthermore, the strategy of analyzing transcriptomes and proteomes of the MSCs may be useful to set the standard for donor variation.

Oncostatin M-Enriched Small Extracellular Vesicles Derived from Mesenchymal Stem Cells Prevent Isoproterenol-Induced Fibrosis and Enhance Angiogenesis

Myocardial fibrosis is a pathological hallmark of cardiac dysfunction. Oncostatin M (OSM) is a pleiotropic cytokine that can promote fibrosis in different organs after sustained exposure. However, OSM released by macrophages during cardiac fibrosis suppresses cardiac fibroblast activation by modulating transforming growth factor beta 1 (TGF-β1) expression and extracellular matrix deposition. Small extracellular vesicles (SEVs) from mesenchymal stromal cells (MSCs) are being investigated to treat myocardial infarction, using different strategies to bolster their therapeutic ability. Here, we generated TERT-immortalized human MSC cell lines (MSC-T) engineered to overexpress two forms of cleavage-resistant OSM fused to CD81TM (OSM-SEVs), which allows the display of the cytokine at the surface of secreted SEVs. The therapeutic potential of OSM-SEVs was assessed in vitro using human cardiac ventricular fibroblasts (HCF-Vs) activated by TGF-β1. Compared with control SEVs, OSM-loaded SEVs reduced proliferation in HCF-V and blunted telo-collagen expression. When injected intraperitoneally into mice treated with isoproterenol, OSM-loaded SEVs reduced fibrosis, prevented cardiac hypertrophy, and increased angiogenesis. Overall, we demonstrate that the enrichment of functional OSM on the surface of MSC-T-SEVs increases their potency in terms of anti-fibrotic and pro-angiogenic properties, which opens new perspectives for this novel biological product in cell-free-based therapies.

Adipose-Derived Stromal Cells within a Gelatin Matrix Acquire Enhanced Regenerative and Angiogenic Properties: A Pre-Clinical Study for Application to Chronic Wounds

This study evaluates the influence of a gelatin sponge on adipose-derived stromal cells (ASC). Transcriptomic data revealed that, compared to ASC in a monolayer, a cross-linked porcine gelatin sponge strongly influences the transcriptome of ASC. Wound healing genes were massively regulated, notably with the inflammatory and angiogenic factors. Proteomics on conditioned media showed that gelatin also acted as a concentrator and reservoir of the regenerative ASC secretome. This secretome promoted fibroblast survival and epithelialization, and significantly increased the migration and tubular assembly of endothelial cells within fibronectin. ASC in gelatin on a chick chorioallantoic membrane were more connected to vessels than an empty sponge, confirming an increased angiogenesis in vivo. No tumor formation was observed in immunodeficient nude mice to which an ASC gelatin sponge was transplanted subcutaneously. Finally, ASC in a gelatin sponge prepared from outbred rats accelerated closure and re-vascularization of ischemic wounds in the footpads of rats. In conclusion, we provide here preclinical evidence that a cross-linked porcine gelatin sponge is an optimal carrier to concentrate and increase the regenerative activity of ASC, notably angiogenic. This formulation of ASC represents an optimal, convenient and clinically compliant option for the delivery of ASC on ischemic wounds.

The Implications of Microglial Regulation in Neuroplasticity-Dependent Stroke Recovery

Stroke causes varying degrees of neurological deficits, leading to corresponding dysfunctions. There are different therapeutic principles for each stage of pathological development. Neuroprotection is the main treatment in the acute phase, and functional recovery becomes primary in the subacute and chronic phases. Neuroplasticity is considered the basis of functional restoration and neurological rehabilitation after stroke, including the remodeling of dendrites and dendritic spines, axonal sprouting, myelin regeneration, synapse shaping, and neurogenesis. Spatiotemporal development affects the spontaneous rewiring of neural circuits and brain networks. Microglia are resident immune cells in the brain that contribute to homeostasis under physiological conditions. Microglia are activated immediately after stroke, and phenotypic polarization changes and phagocytic function are crucial for regulating focal and global brain inflammation and neurological recovery. We have previously shown that the development of neuroplasticity is spatiotemporally consistent with microglial activation, suggesting that microglia may have a profound impact on neuroplasticity after stroke and may be a key therapeutic target for post-stroke rehabilitation. In this review, we explore the impact of neuroplasticity on post-stroke restoration as well as the functions and mechanisms of microglial activation, polarization, and phagocytosis. This is followed by a summary of microglia-targeted rehabilitative interventions that influence neuroplasticity and promote stroke recovery.

Vascular Progenitor Cells: From Cancer to Tissue Repair

Vascular progenitor cells are activated to repair and form a neointima following vascular damage such as hypertension, atherosclerosis, diabetes, trauma, hypoxia, primary cancerous lesions and metastases as well as catheter interventions. They play a key role not only in the resolution of the vascular lesion but also in the adult neovascularization and angiogenesis sprouting (i.e., the growth of new capillaries from pre-existing ones), often associated with carcinogenesis, favoring the formation of metastases, survival and progression of tumors. In this review, we discuss the biology, cellular plasticity and pathophysiology of different vascular progenitor cells, including their origins (sources), stimuli and activated pathways that induce differentiation, isolation and characterization. We focus on their role in tumor-induced vascular injury and discuss their implications in promoting tumor angiogenesis during cancer proliferation and migration.

Identification of molecularly unique tumor-associated mesenchymal stromal cells in breast cancer patients

The tumor microenvironment is a complex mixture of cell types that bi-directionally interact and influence tumor initiation, progression, recurrence, and patient survival. Mesenchymal stromal cells (MSCs) of the tumor microenvironment engage in crosstalk with cancer cells to mediate epigenetic control of gene expression. We identified CD90+ MSCs residing in the tumor microenvironment of patients with invasive breast cancer that exhibit a unique gene expression signature. Single-cell transcriptional analysis of these MSCs in tumor-associated stroma identified a distinct subpopulation characterized by increased expression of genes functionally related to extracellular matrix signaling. Blocking the TGFβ pathway reveals that these cells directly contribute to cancer cell proliferation. Our findings provide novel insight into communication between breast cancer cells and MSCs that are consistent with an epithelial to mesenchymal transition and acquisition of competency for compromised control of proliferation, mobility, motility, and phenotype.

Enriched adipose stem cell secretome as an effective therapeutic strategy for in vivo wound repair and angiogenesis

The therapeutic potential of adipose tissue-derived mesenchymal stem cells (ADMSCs) is well studied for use in non-healing wounds. However, concerns on the transplantable cell number requirement, cell expansion, cell viability, retained cell multipotency and the limited cell implantation time for efficient impact hinders cell therapy. Recent literature is much inclined to the superiority of the ADMSCs' secretome, pre-dominating its paracrine-mediated therapeutic impact. In this context, the possibility of attaining accelerated wound angiogenesis through non-viral mediated enrichment of the ADMSCs secretome with pro-angiogenic growth factors (AGF) seems promising. Accordingly, this study aimed to explore the effect of AGF-enriched ADMSCs secretome for accelerating wound angiogenesis and repair in acute large area full thickness excision rabbit wound model, as adopted from Salgado et al. (Chir Buchar Rom 108:706-710, 1990). Using sub-dermal single-dose injections along the margin of the dorsal wound, native ADMSCs secretome, AGF-enriched ADMSC secretome, allogenic rabbit ADMSCs and a combination of AGF-enriched ADMSC secretome with allogenic rabbit ADMSCs were transplanted independently. Twenty-eight days (28 days) post-transplantation, histopathological analysis was performed to assess the effect. Hematoxylin and eosin (H&E) staining showed enhanced epithelization, notable granulation tissue and collagen fiber deposition in AGF-enriched secretome transplanted groups. This was confirmed by elevated CD31 detection, faster wound closure time and collagen organization. The use of single-dose AGF-enriched ADMSCs' secretome for therapeutic angiogenesis and wound repair seems to be a promising cell-free therapeutic option. Further investigations using multiple doses on larger animal groups remains to be explored in order to ascertain the comparative potential of AGF-enriched ADMSCs' secretome.

Exosomes derived from Nr-CWS pretreated MSCs facilitate diabetic wound healing by promoting angiogenesis via the circIARS1/miR-4782-5p/VEGFA axis

Mesenchymal stem cell (MSC)-derived exosomes (Exos) were reported to a prospective candidate in accelerating diabetic wound healing due to their pro-angiogenic effect. MSCs pretreated with chemistry or biology factors were reported to advance the biological activities of MSC-derived exosomes. Hence, this study was designed to explore whether exosomes derived from human umbilical cord MSCs (hucMSCs) preconditioned with Nocardia rubra cell wall skeleton (Nr-CWS) exhibited superior proangiogenic effect on diabetic wound repair and its underlying molecular mechanisms. The results showed that Nr-CWS-Exos facilitated the proliferation, migration and tube formation of endothelial cells in vitro. In vivo, Nr-CWS-Exos exerted great effect on advancing wound healing by facilitating the angiogenesis of wound tissues compared with Exos. Furthermore, the expression of circIARS1 increased after HUVECs were treated with Nr-CWS-Exos. CircIARS1 promoted the pro-angiogenic effects of Nr-CWS-Exos on endothelial cellsvia the miR-4782-5p/VEGFA axis. Taken together, those data reveal that exosomes derived from Nr-CWS-pretreated MSCs might serve as an underlying strategy for diabetic wound treatment through advancing the biological function of endothelial cells via the circIARS1/miR-4782-5p/VEGFA axis.

Extracellular Vesicles from Mesenchymal Stem Cells: Towards Novel Therapeutic Strategies for Neurodegenerative Diseases

Neurodegenerative diseases are fatal disorders of the central nervous system (CNS) which currently lack effective treatments. The application of mesenchymal stem cells (MSCs) represents a new promising approach for treating these incurable disorders. Growing evidence suggest that the therapeutic effects of MSCs are due to the secretion of neurotrophic molecules through extracellular vesicles. The extracellular vesicles produced by MSCs (MSC-EVs) have valuable innate properties deriving from parental cells and could be exploited as cell-free treatments for many neurological diseases. In particular, thanks to their small size, they are able to overcome biological barriers and reach lesion sites inside the CNS. They have a considerable pharmacokinetic and safety profile, avoiding the critical issues related to the fate of cells following transplantation. This review discusses the therapeutic potential of MSC-EVs in the treatment of neurodegenerative diseases, focusing on the strategies to further enhance their beneficial effects such as tracking methods, bioengineering applications, with particular attention to intranasal delivery as a feasible strategy to deliver MSC-EVs directly to the CNS in an effective and minimally invasive way. Current progresses and limiting issues to the extent of the use of MSC-EVs treatment for human neurodegenerative diseases will be also revised.

Mesenchymal Stem Cells and Their Exocytotic Vesicles

Mesenchymal stem cells (MSCs), as a kind of pluripotent stem cells, have attracted much attention in orthopedic diseases, geriatric diseases, metabolic diseases, and sports functions due to their osteogenic potential, chondrogenic differentiation ability, and adipocyte differentiation. Anti-inflammation, anti-fibrosis, angiogenesis promotion, neurogenesis, immune regulation, and secreted growth factors, proteases, hormones, cytokines, and chemokines of MSCs have been widely studied in liver and kidney diseases, cardiovascular and cerebrovascular diseases. In recent years, many studies have shown that the extracellular vesicles of MSCs have similar functions to MSCs transplantation in all the above aspects. Here we review the research progress of MSCs and their exocrine vesicles in recent years.