Apoptotic bodies extracted from adipose mesenchymal stem cells carry microRNA-21-5p to induce M2 polarization of macrophages and augment skin wound healing by targeting KLF6

Apoptotic Extracellular Vesicles from Supernumerary Tooth-Derived Pulp Stem Cells Transfer COL1A1 to Promote Angiogenesis via PI3K/Akt/VEGF Pathway

Purpose

Angiogenesis is a tightly controlled process that initiates the formation of new vessels and its dysfunction can lead to life-threatening diseases. Apoptotic extracellular vesicles (ApoEVs) have emerged as a proangiogenic agent with high safety and isolation efficiency profile, and ApoEVs from supernumerary tooth-derived pulp stem cells (SNTSC-ApoEVs) have their unique advantages with an easily accessible parental cell source and non-invasive cell harvesting. However, the detailed characteristics of SNTSC-ApoEVs are largely unknown. This study aimed to investigate the proangiogenic capacity and function molecule of SNTSC-ApoEVs.

Methods

SNTSC-ApoEVs were isolated and characterized. In vitro effects of SNTSC-ApoEVs on the proliferation, migration, and tube formation of human umbilical vein endothelial cells (HUVECs) were evaluated by CCK-8, wound healing, transwell, and tube formation assays. The mRNA and protein levels of proangiogenic genes were quantified by qRT-PCR, Western blot, and immunofluorescence analysis. A Matrigel plug model was established in 6-week-old male nu/nu mice for one week, and the in vivo impact of SNTSC-ApoEVs on micro-vessel formation was assessed by histological analysis. Proteomic analysis and RNA sequencing were performed to explore the active ingredients and underlying mechanisms.

Results

SNTSC-ApoEVs enhanced the proliferation, migration, and angiogenesis of HUVECs in vitro. In the Matrigel plug model in vivo, SNTSC-ApoEVs promoted CD31-positive luminal structure formation. Apart from expressing general ApoEV markers, SNTSC-ApoEVs were enriched with multiple proteins related to extracellular matrix-cell interactions. Mechanistically, SNTSC-ApoEVs transferred COL1A1 to HUVECs and promoted endothelial functions by activating the PI3K/Akt/VEGF cascade.

Conclusion

SNTSC-ApoEVs can promote angiogenesis by transferring the functional molecule COL1A1 and activating the PI3K/Akt/VEGF pathway, making SNTSC-ApoEVs a promising strategy for the treatment of angiogenesis-related diseases.

Apoptotic Bodies Derived from Fibroblast-Like Cells in Subcutaneous Connective Tissue Inhibit Ferroptosis in Ischaemic Flaps via the miR-339-5p/KEAP1/Nrf2 Axis

Preventing and treating avascular necrosis at the distal end of the flaps are critical to surgery success, but current treatments are not ideal. A recent study shows that apoptotic bodies (ABs) generated near the site of apoptosis can be taken up and promote cell proliferation. The study reveals that ABs derived from fibroblast-like cells in the subcutaneous connective tissue (FSCT cells) of skin flaps promoted ischaemic flap survival. It is also found that ABs inhibited cell death and oxidative stress and promoted M1-to-M2 polarization in macrophages. Transcriptome sequencing and protein level testing demonstrated that ABs promoted ischaemic flap survival in endothelial cells and macrophages by inhibiting ferroptosis via the KEAP1-Nrf2 axis. Furthermore, microRNA (miR) sequencing data and in vitro and in vivo experiments demonstrated that ABs inhibited KEAP1 by delivering miR-339-5p to exert therapeutic effects. In conclusion, FSCT cell-derived ABs inhibited ferroptosis, promoted the macrophage M1-to-M2 transition via the miR-339-5p/KEAP1/Nrf2 axis and promoted ischaemic flap survival. These results provide a potential therapeutic strategy to promote ischaemic flap survival by administering ABs.

Roles of extracellular vesicles on macrophages in inflammatory bone diseases

Inflammatory bone disease is a general term for a series of diseases caused by chronic inflammation, which leads to the destruction of bone homeostasis, that is, the osteolytic activity of osteoclasts increases, and the osteogenic activity of osteoblasts decreases, leading to osteolysis. Macrophages are innate immune cell with plasticity, and their polarization is related to inflammatory bone diseases. The dynamic balance of macrophages between the M1 phenotype and the M2 phenotype affects the occurrence and development of diseases. In recent years, an increasing number of studies have shown that extracellular vesicles existing in the extracellular environment can act on macrophages, affecting the progress of inflammatory diseases. This process is realized by influencing the physiological activity or functional activity of macrophages, inducing macrophages to secrete cytokines, and playing an anti-inflammatory or pro-inflammatory role. In addition, by modifying and editing extracellular vesicles, the potential of targeting macrophages can be used to provide new ideas for developing new drug carriers for inflammatory bone diseases.

Exploring miR-21 as a key regulator in two distinct approaches of bone marrow stromal cells differentiation into Schwann-like cells

The differentiation of bone marrow stromal cells (BMSCs) into Schwann-like cells (SCLCs) has the potential to promote the structural and functional restoration of injured axons. However, the optimal induction protocol and its underlying mechanisms remain unclear. This study aimed to compare the effectiveness of different induction protocols in promoting the differentiation of rat BMSCs into SCLCs and to explore their potential mechanisms. BMSCs were induced using two distinct methods: a composite factor induction approach (Protocol-1) and a conditioned culture medium induction approach (Protocol-2). The expression of Schwann cells (SCs) marker proteins and neurotrophic factors (NTFs) in the differentiated cells was assessed. Cell proliferation and apoptosis were also measured. During induction, changes in miR-21 and Sprouty RTK signaling antagonist 2 (SPRY2) mRNA were analyzed. Following the transfection of BMSCs with miR-21 agomir or miR-21 antagomir, induction was carried out using both protocols, and the expression of SPRY2, ERK1/2, and SCs marker proteins was examined. The results revealed that NTFs expression was higher in Protocol-1, whereas SCs marker proteins expression did not significantly differ between the two groups. Compared to Protocol-1, Protocol-2 exhibited enhanced cell proliferation and fewer apoptotic and necrotic cells. Both protocols showed a negative correlation between miR-21 and SPRY2 expression throughout the induction stages. After induction, the miR-21 agomir group exhibited reduced SPRY2 expression, increased ERK1/2 expression, and significantly elevated expression of SCs marker proteins. This study demonstrates that Protocol-1 yields higher NTFs expression, whereas Protocol-2 results in stronger SCLCs proliferation. Upregulating miR-21 suppresses SPRY2 expression, activates the ERK1/2 signaling pathway, and promotes BMSC differentiation into SCLCs.

The Immunomodulatory effect of exosomes in diabetes: a novel and attractive therapeutic tool in diabetes therapy

Exosomes carry proteins, metabolites, nucleic acids and lipids from their parent cell of origin. They are derived from cells through exocytosis, are ingested by target cells, and can transfer biological signals between local or distant cells. Therefore, exosomes are often modified in reaction to pathological processes, including infection, cancer, cardiovascular diseases and in response to metabolic perturbations such as obesity and diabetes, all of which involve a significant inflammatory aspect. Here, we discuss how immune cell-derived exosomes origin from neutrophils, T lymphocytes, macrophages impact on the immune reprogramming of diabetes and the associated complications. Besides, exosomes derived from stem cells and their immunomodulatory properties and anti-inflammation effect in diabetes are also reviewed. Moreover, As an important addition to previous reviews, we describes promising directions involving engineered exosomes as well as current challenges of clinical applications in diabetic therapy. Further research on exosomes will explore their potential in translational medicine and provide new avenues for the development of effective clinical diagnostics and therapeutic strategies for immunoregulation of diabetes.

Functional diversity of apoptotic vesicle subpopulations from bone marrow mesenchymal stem cells in tissue regeneration

Apoptosis releases numerous apoptotic vesicles that regulate processes such as cell proliferation, immunity, and tissue regeneration and repair. Now, it has also emerged as an attractive candidate for biotherapeutics. However, apoptotic vesicles encompass a diverse range of subtypes, and it remains unclear which specific subtypes play a pivotal role. In this study, we successfully isolated different apoptotic vesicle subtypes based on their sizes and characterized them using NTA and TEM techniques, respectively. We compared the functional variances among the distinct subtypes of apoptotic vesicles in terms of stem cell proliferation, migration, and differentiation, as well as for endothelial cell and macrophage function, effectively identifying subtypes that exhibit discernible functional differences. ApoSEV (with diameter <1000 nm) promoted stem cell proliferation, migration, and multi-potent differentiation, and accelerated skin wound healing of diabetes mouse model, while apoBD (with diameter >1000 nm) played the opposite effect on cell function and tissue regeneration. Lastly, employing protein analysis and gene sequencing techniques, we elucidated the intrinsic mechanisms underlying these differences between different subtypes of apoEVs. Collectively, this study identified that apoptotic vesicle subtypes possessed distinct bio-functions in regulating stem cell function and behaviour and modulating tissue regeneration, which primarily attribute to the distinct profiling of protein and mRNA in different subtypes. This comprehensive analysis of specific subtypes of apoEVs would provide novel insights for potential therapeutic applications in cell biology and tissue regeneration.

The Role of Extracellular Vesicles in the Pathogenesis and Treatment of Rheumatoid Arthritis and Osteoarthritis

Cells can communicate with each other through extracellular vesicles (EVs), which are membrane-bound structures that transport proteins, lipids and nucleic acids. These structures have been found to mediate cellular differentiation and proliferation apoptosis, as well as inflammatory responses and senescence, among others. The cargo of these vesicles may include immunomodulatory molecules, which can then contribute to the pathogenesis of various diseases. By contrast, EVs secreted by mesenchymal stem cells (MSCs) have shown important immunosuppressive and regenerative properties. Moreover, EVs can be modified and used as drug carriers to precisely deliver therapeutic agents. In this review, we aim to summarize the current evidence on the roles of EVs in the progression and treatment of rheumatoid arthritis (RA) and osteoarthritis (OA), which are important and prevalent joint diseases with a significant global burden.

Advances in biological functions and applications of apoptotic vesicles

BACKGROUND

Apoptotic vesicles are extracellular vesicles generated by apoptotic cells that were previously regarded as containing waste or harmful substances but are now thought to play an important role in signal transduction and homeostasis regulation.

METHODS

In the present review, we reviewed many articles published over the past decades on the subtypes and formation of apoptotic vesicles and the existing applications of these vesicles.

RESULTS

Apoptotic bodies were once regarded as vesicles released by apoptotic cells, however, apoptotic vesicles are now regarded to include apoptotic bodies, apoptotic microvesicles and apoptotic exosomes, which exhibit variation in terms of biogenesis, sizes and properties. Applications of apoptotic vesicles were first reported long ago, but such reports have been rarer than those of other extracellular vesicles. At present, apoptotic vesicles have been utilized mainly in four aspects, including in direct therapeutic applications, in their engineering as carriers, in their construction as vaccines and in their utilization in diagnosis.

CONCLUSION

Building on a deeper understanding of their composition and characteristics, some studies have utilized apoptotic vesicles to treat diseases in more novel ways. However, their limitations for clinical translation, such as heterogeneity, have also emerged. In general, apoptotic vesicles have great application potential, but there are still many barriers to overcome in their investigation. Video Abstract.

Mesenchymal Stem Cells-Derived Apoptotic Extracellular Vesicles (ApoEVs): Mechanism and Application in Tissue Regeneration

Mesenchymal stem cells (MSCs) are commonly used as a source for cellular therapy owing to their strong immunosuppressive and regenerative effects. However, MSCs undergo extensive apoptosis within a short period after transplantation. During apoptosis, MSCs generate several apoptotic extracellular vesicles (MSCs-ApoEVs). MSCs-ApoEVs are rich in miRNomes, metabolites, and proteomes. They are critical intercellular communication mediators that can exert different regulatory effects on recipient cells. MSCs-ApoEVs have been shown to promote regeneration in the skin, hair, bone, muscle, and vascular system, etc. This review describes the production, release, isolation, and functionality of ApoEVs in detail. Furthermore, we summarize the existing mechanisms of MSCs-ApoEVs used for tissue regeneration and evaluate the possible strategies for their clinical application.

Extracellular vesicle-mediated interorgan communication in metabolic diseases

The body partially maintains metabolic homeostasis through interorgan communication between metabolic organs under physiological conditions. This crosstalk is known to be mediated by hormones or metabolites, and has recently been expanding to include extracellular vesicles (EVs). EVs participate in interorgan communication under physiological and pathological conditions by encapsulating various bioactive cargoes, including proteins, metabolites, and nucleic acids. In this review we summarize the latest findings about the metabolic regulation of EV biogenesis, secretion, and components, and highlight the biological role of EV cargoes in interorgan communication in cancer, obesity, diabetes, and cardiovascular disease. We also discuss the potential application of EVs as diagnostic markers, and corresponding therapeutic strategies by EV engineering for both early detection and treatment of metabolic disorders.

Mechanisms and applications of adipose-derived stem cell-extracellular vesicles in the inflammation of wound healing

Wound healing is a sophisticated process consisting of serial phases with overlaps, including hemostasis, inflammation, proliferation, and remodeling. The inflammation response is an early response that plays a crucial role in eliminating microbes and clearing damaged cell debris. However, in some pathological circumstances, such as diabetes mellitus, ischemia, trauma, deep burn, etc., abnormal inflammation can cause impaired wound healing. Adipose-derived stem cells (ADSCs) belong to the mesenchymal stem cell (MSC) family and exhibit prospective applications in tissue regeneration and dermatological repairs. ADSC-secreted extracellular vesicles (ADSC-EVs) mimic the functions of ADSCs without the concerns of cell survival, immune response, or ethical issues. Studies have revealed that ADSC-EVs can inhibit abnormal inflammation responses and accelerate wound healing through various mechanisms. Moreover, some studies explored modifications in the cargo components of ADSC-EVs to enhance their therapeutic efficacy. Given the increasing studies focusing on the potential of ADSC-EVs in wound healing, how they interfere with different phases of this process has been investigated in pieces. In this review, we summarized all up-to-date evidence to map a clearer picture of the underlying mechanisms of ADSC-EVs in inflammation response. The applications of ADSC-EVs aiming at inflammation in the healing process were also reviewed to provide therapeutic strategies for future investigators.

Advances in mesenchymal stem/stromal cell-based therapy and their extracellular vesicles for skin wound healing

Wound healing is a dynamic and complicated process containing overlapping phases. Presently, definitive therapy is not available, and the investigation into optimal wound care is influenced by the efficacy and cost-effectiveness of developing therapies. Accumulating evidence demonstrated the potential role of mesenchymal stem/stromal cell (MSC) therapy in several tissue injuries and diseases due to their high proliferation and differentiation abilities along with an easy collection procedure, low tumorigenesis, and immuno-privileged status. MSCs have also accelerated wound repair in all phases through their advantageous properties, such as accelerating wound closure, improving re-epithelialization, elevating angiogenesis, suppressing inflammation, and modulating extracellular matrix (ECM) remodeling. In addition, the beneficial therapeutic impacts of MSCs are largely associated with their paracrine functions, including extracellular vesicles (EVs). Exosomes and microvesicles are the two main subgroups of EVs. These vesicles are heterogeneous bilayer membrane structures that contain several proteins, lipids, and nucleic acids. EVs have emerged as a promising alternative to stem cell-based therapies because of their lower immunogenicity, tumorigenicity, and ease of management. MSCs from various sources have been widely investigated in skin wound healing and regeneration. Considering these features, in this review, we highlighted recent studies that the investigated therapeutic potential of various MSCs and MSC-EVs in skin damages and wounds.

Potential Pathogenic Impact of Cow’s Milk Consumption and Bovine Milk-Derived Exosomal MicroRNAs in Diffuse Large B-Cell Lymphoma

Epidemiological evidence supports an association between cow’s milk consumption and the risk of diffuse large B-cell lymphoma (DLBCL), the most common non-Hodgkin lymphoma worldwide. This narrative review intends to elucidate the potential impact of milk-related agents, predominantly milk-derived exosomes (MDEs) and their microRNAs (miRs) in lymphomagenesis. Upregulation of PI3K-AKT-mTORC1 signaling is a common feature of DLBCL. Increased expression of B cell lymphoma 6 (BCL6) and suppression of B lymphocyte-induced maturation protein 1 (BLIMP1)/PR domain-containing protein 1 (PRDM1) are crucial pathological deviations in DLBCL. Translational evidence indicates that during the breastfeeding period, human MDE miRs support B cell proliferation via epigenetic upregulation of BCL6 (via miR-148a-3p-mediated suppression of DNA methyltransferase 1 (DNMT1) and miR-155-5p/miR-29b-5p-mediated suppression of activation-induced cytidine deaminase (AICDA) and suppression of BLIMP1 (via MDE let-7-5p/miR-125b-5p-targeting of PRDM1). After weaning with the physiological termination of MDE miR signaling, the infant’s BCL6 expression and B cell proliferation declines, whereas BLIMP1-mediated B cell maturation for adequate own antibody production rises. Because human and bovine MDE miRs share identical nucleotide sequences, the consumption of pasteurized cow’s milk in adults with the continued transfer of bioactive bovine MDE miRs may de-differentiate B cells back to the neonatal “proliferation-dominated” B cell phenotype maintaining an increased BLC6/BLIMP1 ratio. Persistent milk-induced epigenetic dysregulation of BCL6 and BLIMP1 expression may thus represent a novel driving mechanism in B cell lymphomagenesis. Bovine MDEs and their miR cargo have to be considered potential pathogens that should be removed from the human food chain.

"Find-eat" strategy targeting endothelial cells via receptor functionalized apoptotic body nanovesicle

Endothelial cell (EC) injury plays a key role in the chronic wound process. A long-term hypoxic microenvironment hinders the vascularization of ECs, thus delaying wound healing. In this study, CX3CL1-functionalized apoptotic body nanovesicles (nABs) were constructed. The "Find-eat" strategy was implemented through a receptor-ligand combination to target ECs that highly express CX3CR1 in the hypoxic microenvironment, therefore amplifying the "Find-eat" signal and promoting angiogenesis. Apoptotic bodies (ABs) were obtained by chemically inducing apoptosis of adipose-derived stem cells (ADSCs), and then functionalized nABs containing deferoxamine (DFO-nABs) were obtained through a series of steps, including optimized hypotonic treatment, mild ultrasound, drug mixing and extrusion treatment. In vitro experiments showed that nABs had good biocompatibility and an effective "Find-eat" signal via CX3CL1/CX3CR1 to induce ECs in the hypoxic microenvironment, thereby promoting cell proliferation, cell migration and tube formation. In vivo experiments showed that nABs could promote the rapid closure of wounds, release the "Find-eat" signal to target ECs and realize the sustained release of angiogenic drugs to promote new blood vessel formation in diabetic wounds. These receptor-functionalized nABs, which can target ECs by releasing dual signals and achieve the sustained release of angiogenic drugs, may provide a novel strategy for chronic diabetic wound healing.

Apoptotic bodies for advanced drug delivery and therapy

Extracellular vesicles (EVs) have emerged as promising candidates for multiple biomedical applications. Major types of EVs include exosomes, microvesicles, and apoptotic bodies (ABs). ABs are conferred most properties from parent cells in the final stages of apoptosis. A wide variety of sources and stable morphological features are endowed to ABs by the rigorous apoptotic program. ABs accommodate more functional biomolecules by relying on the larger volume and maintaining their naturalness in circulation. The predominant body surface ratio of ABs facilitates their recognition by recipient cells and is advantageous for interactions with microenvironments. ABs can modulate and alleviate symptoms of numerous diseases for their origins, circulation, and high biocompatibility. In addition, ABs have been emerging in disease diagnosis, immunotherapy, regenerative therapy, and drug delivery. Here, we aim to present a thorough discussion on current knowledge about ABs. Of particular interest, we will summarize the application of AB-based strategies for diagnosis and disease therapy. Perspectives for the development of ABs in biomedical applications are highlighted.

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.

Mesenchymal Stromal Cell-Derived Extracellular Vesicles as Biological Carriers for Drug Delivery in Cancer Therapy

Cancer is the second leading cause of death worldwide, with 10.0 million cancer deaths in 2020. Despite advances in targeted therapies, some pharmacological drawbacks associated with anticancer chemo and immunotherapeutic agents include high toxicities, low bioavailability, and drug resistance. In recent years, extracellular vesicles emerged as a new promising platform for drug delivery, with the advantage of their inherent biocompatibility and specific targeting compared to artificial nanocarriers, such as liposomes. Particularly, mesenchymal stem/stromal cells were proposed as a source of extracellular vesicles for cancer therapy because of their intrinsic properties: high in vitro self-renewal and proliferation, regenerative and immunomodulatory capacities, and secretion of extracellular vesicles that mediate most of their paracrine functions. Moreover, extracellular vesicles are static and safer in comparison with mesenchymal stem/stromal cells, which can undergo genetic/epigenetic or phenotypic changes after their administration to patients. In this review, we summarize currently reported information regarding mesenchymal stem/stromal cell-derived extracellular vesicles, their proper isolation and purification techniques - from either naive or engineered mesenchymal stem/stromal cells - for their application in cancer therapy, as well as available downstream modification methods to improve their therapeutic properties. Additionally, we discuss the challenges associated with extracellular vesicles for cancer therapy, and we review some preclinical and clinical data available in the literature.