Sequential paracrine mechanisms are necessary for the therapeutic benefits of stem cell therapy

Decoded cardiopoietic cell secretome linkage to heart repair biosignature

Cardiopoiesis-primed human stem cells exert sustained benefit in treating heart failure despite limited retention following myocardial delivery. To assess potential paracrine contribution, the secretome of cardiopoiesis conditioned versus naïve human mesenchymal stromal cells was decoded by directed proteomics augmented with machine learning and systems interrogation. Cardiopoiesis doubled cellular protein output generating a distinct secretome that segregated the conditioned state. Altering the expression of 1035 secreted proteins, cardiopoiesis reshaped the secretome across functional classes. The resolved differential cardiopoietic secretome was enriched in mesoderm development and cardiac progenitor signaling processes, yielding a cardiovasculogenic profile bolstered by upregulated cardiogenic proteins. In tandem, cardiopoiesis enhanced the secretion of immunomodulatory proteins associated with cytokine signaling, leukocyte migration, and chemotaxis. Network analysis integrated the differential secretome within an interactome of 1745 molecules featuring prioritized regenerative processes. Secretome contribution to the repair signature of cardiopoietic cell-treated infarcted hearts was assessed in a murine coronary ligation model. Intramyocardial delivery of cardiopoietic cells improved the performance of failing hearts, with undirected proteomics revealing 50 myocardial proteins responsive to cell therapy. Pathway analysis linked the secretome to cardiac proteome remodeling, pinpointing 17 cardiopoiesis-upregulated secretome proteins directly upstream of 44% of the cell therapy-responsive cardiac proteome. Knockout, in silico, of this 22-protein secretome-dependent myocardial ensemble eliminated indices of the repair signature. Accordingly, in vivo, cell therapy rendered the secretome-dependent myocardial proteome of an infarcted heart indiscernible from healthy counterparts. Thus, the secretagogue effect of cardiopoiesis transforms the human stem cell secretome, endows regenerative competency, and upregulates candidate paracrine effectors of cell therapy-mediated molecular restitution.

Synergistic Interaction between Polysaccharide-Based Extracellular Matrix and Mineralized Osteoblast-Derived EVs Promotes Bone Regeneration via miRNA-mRNA Regulatory Axis

Extracellular vesicles (EVs) derived from bone progenitor cells are advantageous as cell-free and non-immunogenic cargo delivery vehicles. In this study, EVs are isolated from MC3T3-E1 cells before (GM-EVs) and after mineralization for 7 and 14 days (DM-EVs). It was observed that DM-EVs accelerate the process of differentiation in recipient cells more prominently. The small RNA sequencing of EVs revealed that miR-204-5p, miR-221-3p, and miR-148a-3p are among the highly upregulated miRNAs that have an inhibitory effect on the function of mRNAs, Sox11, Timp3, and Ccna2 in host cells, which is probably responsible for enhancing the activity of osteoblastic genes. To enhance the bioavailability of EVs, they are encapsulated in a chitosan-collagen composite hydrogel that serves as a bioresorbable extracellular matrix (ECM). The EVs-integrated scaffold (DM-EVs + Scaffold) enhances bone regeneration in critical-sized calvarial bone defects in rats within 8 weeks of implantation by providing the ECM cues. The shelf life of DM-EVs + Scaffold indicates that the bioactivity of EVs and their cargo in the polymer matrix remains intact for up to 30 days. Integrating mineralized cell-derived EVs into an ECM represents a bioresorbable matrix with a cell-free method for promoting new bone formation through the miRNA-mRNA regulatory axis.

Mesenchymal stem cell-derived extracellular vesicles: a regulator and carrier for targeting bone-related diseases

The escalating threat of bone-related diseases poses a significant challenge to human health. Mesenchymal stem cell (MSC)-derived extracellular vesicles (MSC-EVs), as inherent cell-secreted natural products, have emerged as promising treatments for bone-related diseases. Leveraging outstanding features such as high biocompatibility, low immunogenicity, superior biological barrier penetration, and extended circulating half-life, MSC-EVs serve as potent carriers for microRNAs (miRNAs), long no-code RNAs (lncRNAs), and other biomolecules. These cargo molecules play pivotal roles in orchestrating bone metabolism and vascularity through diverse mechanisms, thereby contributing to the amelioration of bone diseases. Additionally, engineering modifications enhance the bone-targeting ability of MSC-EVs, mitigating systemic side effects and bolstering their clinical translational potential. This review comprehensively explores the mechanisms through which MSC-EVs regulate bone-related disease progression. It delves into the therapeutic potential of MSC-EVs as adept drug carriers, augmented by engineered modification strategies tailored for osteoarthritis (OA), rheumatoid arthritis (RA), osteoporosis, and osteosarcoma. In conclusion, the exceptional promise exhibited by MSC-EVs positions them as an excellent solution with considerable translational applications in clinical orthopedics.

Injectable hyperbranched PEG crosslinked hyaluronan hydrogel microparticles containing mir-99a-3p modified subcutaneous ADSCs-derived exosomes was beneficial for long-term treatment of osteoarthritis

Exosomes (Exos) secreted by adipose-derived stem cells (ADSCs) have shown potential in alleviating osteoarthritis (OA). Previous studies indicated that infrapatellar fat pad (IPFP) derived stem cells (IPFSCs) may be more suitable for the treatment of OA than subcutaneous adipose tissue (ScAT) derived stem cells (ScASCs). However, it remains unclear which type of Exos offers superior therapeutic benefit for OA. This study first compared the differences between Exos derived from IPFP stem cells (ExosIPFP) and ScAT stem cells (ExosScAT) in OA treatment. Results suggested that ExosIPFP significantly inhibit the degradation of cartilage extracellular matrix (ECM) than ExosScAT, following this, the differences in microRNA (miRNA) expression between the two types of Exos using small RNA sequencing were performed. Subsequently, miR-99 b-3p was chosen and over-expressed in ExosScAT (ExosScAT-99b-3p), both in vivo and in vitro experiments demonstrated its efficacy in inhibiting the expression of ADAMTS4, promoting the repair of the ECM in OA. Finally, microfluidic technology was performed to fabricate a hyaluronan-based hydrogel microparticles (HMPs) for encapsulating Exos (HMPs@exos), the injectability, sustained release of Exos and long-term therapeutic effect on OA were validated. In summary, these results suggest miR-99 b-3p regulates the degradation of cartilage ECM by targeting ADAMTS4, the upregulation of miR-99 b-3p in ExosScAT would enable them to exhibit comparable or even superior effectiveness to ExosIPFP for OA treatment, making it a promising approach for OA treatment. Considering the abundant resources of ScAT and the limited availability of IPFP, ScAT harvested through liposuction could be genetically engineered to yield Exos for OA treatment. Furthermore, the encapsulation of Exos in HMPs provides an injectable sustained local drug release system, which could potentially enhance the efficacy of Exos and hold potential as future therapeutic strategies.

Secretome profile of TNF-α-induced human umbilical cord mesenchymal stem cells unveils biological processes relevant to skin wound healing

Aim: To profile and study the proteins responsible for the beneficial effect of the TNF-α-induced human umbilical cord mesenchymal stem cells (hUCMSCs) secretome in wound healing. Methods: The hUCMSCs secretome was generated with (induced) or without (uninduced) TNF-α and was subsequently analyzed by liquid chromatography-mass spectrometry, immunoassay and in vitro scratch assay. Results: Proteomic analysis revealed approximately 260 proteins, including 51 and 55 unique proteins in the induced and uninduced secretomes, respectively. Gene ontology analysis disclosed that differential proteins in the induced secretome mainly involved inflammation-related terms. The induced secretome, consisting of higher levels of FGFb, VEGF, PDGF and IL-6, significantly accelerated wound closure and enhanced MMP-13 secretion in HaCaT keratinocytes. Conclusion: The secretome from induced hUCMSCs includes factors that promote wound closure.

Nanotopographical Cues Tune the Therapeutic Potential of Extracellular Vesicles for the Treatment of Aged Skeletal Muscle Injuries

Skeletal muscle regeneration relies on the tightly temporally regulated lineage progression of muscle stem/progenitor cells (MPCs) from activation to proliferation and, finally, differentiation. However, with aging, MPC lineage progression is disrupted and delayed, ultimately causing impaired muscle regeneration. Extracellular vesicles (EVs) have attracted broad attention as next-generation therapeutics for promoting tissue regeneration. As a next step toward clinical translation, strategies to manipulate EV effects on downstream cellular targets are needed. Here, we developed an engineering strategy to tune the therapeutic potential of EVs using nanotopographical cues. We found that EVs released by young MPCs cultured on flat substrates (fEVs) promoted the proliferation of aged MPCs while EVs released by MPCs cultured on nanogratings (nEVs) promoted myogenic differentiation. We then employed a bioengineered 3D muscle aging model to optimize the administration protocol and test the therapeutic potential of fEVs and nEVs in a high-throughput manner. We found that the sequential administration first of fEVs during the phase of MPC proliferative expansion (i.e., 1 day after injury) followed by nEV administration at the stage of MPC differentiation (i.e., 3 days after injury) enhanced aged muscle regeneration to a significantly greater extent than fEVs and nEVs delivered either in isolation or mixed. The beneficial effects of the sequential EV treatment strategy were further validated in vivo, as evidenced by increased myofiber size and improved functional recovery. Collectively, our study demonstrates the ability of topographical cues to tune EV therapeutic potential and highlights the importance of optimizing the EV administration strategy to accelerate aged skeletal muscle regeneration.

Mesenchymal Stem Cell-Derived Exosomes in Ophthalmology: A Comprehensive Review

Over the past decade, the field of mesenchymal stem cell (MSC) therapy has exhibited rapid growth. Due to their regenerative, reparatory, and immunomodulatory capacities, MSCs have been widely investigated as therapeutic agents in the cell-based treatment of chronic ophthalmic pathologies. However, the applicability of MSC-based therapy is limited by suboptimal biocompatibility, penetration, and delivery to the target ocular tissues. An emerging body of research has elucidated the role of exosomes in the biological functions of MSCs, and that MSC-derived extracellular vesicles (EVs) possess anti-inflammatory, anti-apoptotic, tissue repairing, neuroprotective, and immunomodulatory properties similar to MSCs. The recent advances in MSCs-derived exosomes can serve as solutions to the challenges faced by MSCs-therapy. Due to their nano-dimensions, MSC-derived exosomes can rapidly penetrate biological barriers and reach immune-privileged organs, allowing for efficient delivery of therapeutic factors such as trophic and immunomodulatory agents to ocular tissues that are typically challenging to target by conventional therapy and MSCs transplantation. In addition, the use of EVs minimizes the risks associated with mesenchymal stem cell transplantation. In this literature review, we focus on the studies published between 2017 and 2022, highlighting the characteristics of EVs derived from MSCs and their biological functions in treating anterior and posterior segment ocular diseases. Additionally, we discuss the potential use of EVs in clinical settings. Rapid advancements in regenerative medicine and exosome-based drug delivery, in conjunction with an increased understanding of ocular pathology and pharmacology, hold great promise for the treatment of ocular diseases. The potential of exosome-based therapies is exciting and can revolutionize the way we approach these ocular conditions.

Effect of Atorvastatin on Angiogenesis-Related Genes VEGF-A, HGF and IGF-1 and the Modulation of PI3K/AKT/mTOR Transcripts in Bone-Marrow-Derived Mesenchymal Stem Cells

Stem cell transplantation represents a unique therapeutic tool in tissue engineering and regenerative medicine. However, it was shown that the post-injection survival of stem cells is poor, warranting a more comprehensive understanding of activated regenerative pathways. Numerous studies indicate that statins improve the therapeutic efficacy of stem cells in regenerative medicine. In the present study, we investigated the effect of the most widely prescribed statin, atorvastatin, on the characteristics and properties of bone-marrow-derived mesenchymal stem cells (BM-MSCs) cultured in vitro. We found that atorvastatin did not decrease the viability of BM-MSCs, nor did it change the expression of MSC cell surface markers. Atorvastatin upregulated the mRNA expression levels of VEGF-A and HGF, whereas the mRNA expression level of IGF-1 was decreased. In addition, the PI3K/AKT signaling pathway was modulated by atorvastatin as indicated by the high mRNA expression levels of PI3K and AKT. Moreover, our data revealed the upregulation of mTOR mRNA levels; however, no change was observed in the BAX and BCL-2 transcripts. We propose that atorvastatin benefits BM-MSC treatment due to its ability to upregulate angiogenesis-related genes expression and transcripts of the PI3K/AKT/mTOR pathway.

Exosomes in Myocardial Infarction: Therapeutic Potential and Clinical Application

Myocardial infarction (MI) remains the leading fatal disease in the world, and with subsequent adverse ventricular remodeling often leading to the development of heart failure, finding new ways to improve the prognosis of MI is important. Exosomes are extracellular vesicles of 30-150 nm secreted by various cells in the body. It is now well recognized that exosomes play an important role in MI, and exosomes may become a new approach to post-MI treatment. It is valuable to study how exosomes are involved in post-MI progression and how exosomes can be modified to improve their effectiveness. In this review, we focus on summarizing the therapeutic potential of exosomes for MI and the current status of clinical applications to provide evidence for the formal use of exosomes in the clinic.

Therapeutic potential and mechanisms of mesenchymal stem cell-derived exosomes as bioactive materials in tendon-bone healing

Tendon-bone insertion (TBI) injuries, such as anterior cruciate ligament injury and rotator cuff injury, are the most common soft tissue injuries. In most situations, surgical tendon/ligament reconstruction is necessary for treating such injuries. However, a significant number of cases failed because healing of the enthesis occurs through scar tissue formation rather than the regeneration of transitional tissue. In recent years, the therapeutic potential of mesenchymal stem cells (MSCs) has been well documented in animal and clinical studies, such as chronic paraplegia, non-ischemic heart failure, and osteoarthritis of the knee. MSCs are multipotent stem cells, which have self-renewability and the ability to differentiate into a wide variety of cells such as chondrocytes, osteoblasts, and adipocytes. Numerous studies have suggested that MSCs could promote angiogenesis and cell proliferation, reduce inflammation, and produce a large number of bioactive molecules involved in the repair. These effects are likely mediated by the paracrine mechanisms of MSCs, particularly through the release of exosomes. Exosomes, nano-sized extracellular vesicles (EVs) with a lipid bilayer and a membrane structure, are naturally released by various cell types. They play an essential role in intercellular communication by transferring bioactive lipids, proteins, and nucleic acids, such as mRNAs and miRNAs, between cells to influence the physiological and pathological processes of recipient cells. Exosomes have been shown to facilitate tissue repair and regeneration. Herein, we discuss the prospective applications of MSC-derived exosomes in TBI injuries. We also review the roles of MSC-EVs and the underlying mechanisms of their effects on promoting tendon-bone healing. At last, we discuss the present challenges and future research directions.

Amelioration of ligamentum flavum hypertrophy using umbilical cord mesenchymal stromal cell-derived extracellular vesicles

Ligamentum flavum (LF) hypertrophy (LFH) has been recognised as one of the key contributors to lumbar spinal stenosis. Currently, no effective methods are available to ameliorate this hypertrophy. In this study, human umbilical cord mesenchymal stromal cell-derived extracellular vesicles (hUCMSC-EVs) were introduced for the first time as promising vehicles for drug delivery to treat LFH. The downregulation of miR-146a-5p and miR-221-3p expressions in human LF tissues negatively correlated with increased LF thickness. The hUCMSC-EVs enriched with these two miRNAs significantly suppressed LFH in vivo and notably ameliorated the progression of transforming growth factor β1(TGF-β1)-induced fibrosis in vitro after delivering these two miRNAs to mouse LF cells. The results further demonstrated that miR-146a-5p and miR-221-3p directly bonded to the 3′-UTR regions of SMAD4 mRNA, thereby inhibiting the TGF-β/SMAD4 signalling pathway. Therefore, this translational study determined the effectiveness of a hUCMSC-EVs-based approach for the treatment of LFH and revealed the critical target of miR-146a-5p and miR-221-3p. Our findings provide new insights into promising therapeutics using a hUCMSC-EVs-based delivery system for patients with lumbar spinal stenosis.

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The downregulation of miR-146a-5p and miR-221-3p expressions were negatively correlated with the development of LFH.

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MiR-146a-5p and miR-221-3p enriched in hUCMSC-EVs prevent the fibrosis of LF by targeting SMAD4.

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hUCMSC-EVs are effective as bioactive vehicles to ameliorate the progression of LFH.

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hUCMSC-EVs-based delivery system is a promising therapy for the patients with lumbar spinal stenosis.

Mesenchymal Stem Cell Mechanisms of Action and Clinical Effects in Osteoarthritis: A Narrative Review

With the insufficient satisfaction rates and high cost of operative treatment for osteoarthritis (OA), alternatives have been sought. Furthermore, the inability of current medications to arrest disease progression has led to rapidly growing clinical research relating to mesenchymal stem cells (MSCs). The availability and function of MSCs vary according to tissue source. The three primary sources include the placenta, bone marrow, and adipose tissue, all of which offer excellent safety profiles. The primary mechanisms of action are trophic and immunomodulatory effects, which prevent the further degradation of joints. However, the function and degree to which benefits are observed vary significantly based on the exosomes secreted by MSCs. Paracrine and autocrine mechanisms prevent cell apoptosis and tissue fibrosis, initiate angiogenesis, and stimulate mitosis via growth factors. MSCs have even been shown to exhibit antimicrobial effects. Clinical results incorporating clinical scores and objective radiological imaging have been promising, but a lack of standardization in isolating MSCs prevents their incorporation in current guidelines.

Signaling cascades in the failing heart and emerging therapeutic strategies

Chronic heart failure is the end stage of cardiac diseases. With a high prevalence and a high mortality rate worldwide, chronic heart failure is one of the heaviest health-related burdens. In addition to the standard neurohormonal blockade therapy, several medications have been developed for chronic heart failure treatment, but the population-wide improvement in chronic heart failure prognosis over time has been modest, and novel therapies are still needed. Mechanistic discovery and technical innovation are powerful driving forces for therapeutic development. On the one hand, the past decades have witnessed great progress in understanding the mechanism of chronic heart failure. It is now known that chronic heart failure is not only a matter involving cardiomyocytes. Instead, chronic heart failure involves numerous signaling pathways in noncardiomyocytes, including fibroblasts, immune cells, vascular cells, and lymphatic endothelial cells, and crosstalk among these cells. The complex regulatory network includes protein-protein, protein-RNA, and RNA-RNA interactions. These achievements in mechanistic studies provide novel insights for future therapeutic targets. On the other hand, with the development of modern biological techniques, targeting a protein pharmacologically is no longer the sole option for treating chronic heart failure. Gene therapy can directly manipulate the expression level of genes; gene editing techniques provide hope for curing hereditary cardiomyopathy; cell therapy aims to replace dysfunctional cardiomyocytes; and xenotransplantation may solve the problem of donor heart shortages. In this paper, we reviewed these two aspects in the field of failing heart signaling cascades and emerging therapeutic strategies based on modern biological techniques.

Changes in the Transcriptome Profiles of Human Amnion-Derived Mesenchymal Stromal/Stem Cells Induced by Three-Dimensional Culture: A Potential Priming Strategy to Improve Their Properties

Mesenchymal stromal/stem cells (MSCs) are believed to function in vivo as a homeostatic tool that shows therapeutic properties for tissue repair/regeneration. Conventionally, these cells are expanded in two-dimensional (2D) cultures, and, in that case, MSCs undergo genotypic/phenotypic changes resulting in a loss of their therapeutic capabilities. Moreover, several clinical trials using MSCs have shown controversial results with moderate/insufficient therapeutic responses. Different priming methods were tested to improve MSC effects, and three-dimensional (3D) culturing techniques were also examined. MSC spheroids display increased therapeutic properties, and, in this context, it is crucial to understand molecular changes underlying spheroid generation. To address these limitations, we performed RNA-seq on human amnion-derived MSCs (hAMSCs) cultured in both 2D and 3D conditions and examined the transcriptome changes associated with hAMSC spheroid formation. We found a large number of 3D culture-sensitive genes and identified selected genes related to 3D hAMSC therapeutic effects. In particular, we observed that these genes can regulate proliferation/differentiation, as well as immunomodulatory and angiogenic processes. We validated RNA-seq results by qRT-PCR and methylome analysis and investigation of secreted factors. Overall, our results showed that hAMSC spheroid culture represents a promising approach to cell-based therapy that could significantly impact hAMSC application in the field of regenerative medicine.

Basic and Translational Research in Cardiac Repair and Regeneration: JACC State-of-the-Art Review

This paper aims to provide an important update on the recent preclinical and clinical trials using cell therapy strategies and engineered heart tissues for the treatment of postinfarction left ventricular remodeling and heart failure. In addition to the authors’ own works and opinions on the roadblocks of the field, they discuss novel approaches for cardiac remuscularization via the activation of proliferative mechanisms in resident cardiomyocytes or direct reprogramming of somatic cells into cardiomyocytes. This paper’s main mindset is to present current and future strategies in light of their implications for the design of future patient trials with the ultimate objective of facilitating the translation of discoveries in regenerative myocardial therapies to the clinic.

Stem cells and the pursuit of youth, a tale of limitless possibilities and commercial fraud

This article examines the hype generated around the term “stem cell”, and the capitalization of the stem cell craze by the cosmetic industry. It started by introducing product lines containing active ingredients derived from plant stem cells. Then, evolved to using own cells for skin regeneration and hair loss treatment, and allogenic cells for the manufacturing of stem cell-derived products. This article also discusses the missing links for safe and reliable stem cell applications in cosmetics, and why local regulatory bodies, members of the industry and consumers must all work together to stop the illegitimate use of the “stem cell” good name in unsafe or fraudulent commercial practices.

Mesenchymal stem cell-derived exosomes: therapeutic implications for rotator cuff injury

Rotator cuff injuries are a common clinical condition of the shoulder joint. Surgery that involves reattaching the torn tendon to its humeral head bony attachment has a somewhat lower success rate. The scar tissue formed during healing of the rotator cuff leads to poor tendon-related mechanical properties. To promote healing, a range of genetic interventions, as well as cell transplantation, and many other techniques have been explored. In recent years, the therapeutic promise of mesenchymal stem cells (MSCs) has been well documented in animal and clinical studies. Some data have suggested that MSCs can promote angiogenesis, reduce inflammation and cell proliferation and increase collagen deposition. These functions are likely paracrine effects of MSCs, particularly mediated through exosomes. Here, we review the use of MSCs-related exosomes in tissues and organs. We also discuss their potential utility for treating rotator cuff injuries, and explore the underlying mechanisms of their effects.

Therapeutic Properties of Mesenchymal Stromal/Stem Cells: The Need of Cell Priming for Cell-Free Therapies in Regenerative Medicine

Mesenchymal stromal/stem cells (MSCs) are multipotent adult stem cells that support homeostasis during tissue regeneration. In the last decade, cell therapies based on the use of MSCs have emerged as a promising strategy in the field of regenerative medicine. Although these cells possess robust therapeutic properties that can be applied in the treatment of different diseases, variables in preclinical and clinical trials lead to inconsistent outcomes. MSC therapeutic effects result from the secretion of bioactive molecules affected by either local microenvironment or MSC culture conditions. Hence, MSC paracrine action is currently being explored in several clinical settings either using a conditioned medium (CM) or MSC-derived exosomes (EXOs), where these products modulate tissue responses in different types of injuries. In this scenario, MSC paracrine mechanisms provide a promising framework for enhancing MSC therapeutic benefits, where the composition of secretome can be modulated by priming of the MSCs. In this review, we examine the literature on the priming of MSCs as a tool to enhance their therapeutic properties applicable to the main processes involved in tissue regeneration, including the reduction of fibrosis, the immunomodulation, the stimulation of angiogenesis, and the stimulation of resident progenitor cells, thereby providing new insights for the therapeutic use of MSCs-derived products.