Extracellular matrix protein laminin enhances mesenchymal stem cell (MSC) paracrine function through αvβ3/CD61 integrin to reduce cardiomyocyte apoptosis

The Decellularized Cell-Derived Extracellular Matrix Enhances the Paracrine Function of Human Mesenchymal Stromal/Stem Cells

The mesenchymal stromal/stem cells (MSCs) are known to secrete pleiotropic paracrine factors, contributing to tissue regeneration. This unique ability makes MSCs promising therapeutic tools for many diseases, including even those that were previously untreatable. Thus, the development of preconditioning approaches aimed at enhancing the paracrine function of MSCs attracts great interest. In the present work, we studied how the extracellular matrix, the essential part of the native tissue microenvironment, affects the secretory capacity of MSCs of various origins. The MSC-derived decellularized extracellular matrix (dECM), used as the cell culture substrate, triggered strong upregulation of FGF-2, MMP-1, HGF, GRO-α, GRO-β, CXCL-5, CXCL-6, IL-6, IL-8, G-CSF and MCP-1. Functional in vitro tests revealed that conditioned media derived from MSCs cultured on dECM significantly improved 3T3 fibroblast and HaCaT keratinocyte scratch wound healing, stimulated THP-1 monocyte migration and promoted capillary-like HUVEC-based tube formation compared to conditioned media from MSCs grown on plastic. In addition, we found that FAK inhibition promoted dECM-induced upregulation of paracrine factors, suggesting that this kinase participates in the MSCs' paracrine response to dECM. Together, these findings demonstrate that dECM provides cues that considerably enhance the secretory function of MSCs. Thus, dECM usage as a cell culture substrate alone or in combination with a FAK inhibitor may be viewed as a novel MSC preconditioning technique.

Comparative transcriptomic analysis of bovine mesenchymal stromal cells reveals tissue-source and species-specific differences

Mesenchymal stromal cells (MSCs) have the potential to be used as therapeutics, but their efficacy varies due to cellular heterogeneity, which is not fully understood. After characterizing donor-matched bovine MSC from adipose tissue (AT), bone marrow (BM), and peripheral blood (PB), we performed single-cell RNA sequencing (scRNA-seq) to evaluate overarching similarities and differences across these three tissue-derived MSCs. Next, the transcriptomic profiles of the bovine MSCs were compared to those of equine MSCs, derived from the same tissue sources and previously published by our group, and revealed species-specific differences. Finally, the transcriptomic profile from bovine BM-MSCs was compared to mouse and human BM-MSCs and demonstrated that bovine BM-MSCs share more common functionally relevant gene expression profiles with human BM-MSCs than compared to murine BM-MSCs. Collectively, this study presents the cow as a potential non-traditional animal model for translational MSC studies based on transcriptomic profiles similar to human MSCs.

Pulmonary decellularized extracellular matrix (dECM) modified polyethylene terephthalate three-dimensional cell carriers regulate the proliferation and paracrine activity of mesenchymal stem cells

Introduction: Mesenchymal stem cells (MSCs) possess a high degree of self-renewal capacity and in vitro multi-lineage differentiation potential. Decellularized materials have garnered considerable attention due to their elevated biocompatibility, reduced immunogenicity, excellent biodegradability, and the ability to partially mimic the in vivo microenvironment conducive to cell growth. To address the issue of mesenchymal stem cells losing their stem cell characteristics during two-dimensional (2D) cultivation, this study established three-dimensional cell carriers modified with lung decellularized extracellular matrix and assessed its impact on the life activities of mesenchymal stem cells. Methods: This study employed PET as a substrate material, grafting with polydopamine (PDA), and constructing a decellularized extracellular matrix (dECM) coating on its surface, thus creating the PET/PDA/dECM three-dimensional (3D) composite carrier. Subsequently, material characterization of the cellular carriers was conducted, followed by co-culturing with human umbilical cord mesenchymal stem cells in vitro, aiming to investigate the material's impact on the proliferation and paracrine activity of mesenchymal stem cells. Results and Discussion: Material characterization demonstrated successful grafting of PDA and dECM materials, and it had complete hydrophilicity, high porosity, and excellent mechanical properties. The material was rich in various ECM proteins (collagen I, collagen IV , laminin, fibronectin, elastin), indicating good biocompatibility. In long-term in vitro cultivation (14 days) experiments, the PET/PDA/dECM three-dimensional composite carrier significantly enhanced adhesion and proliferation of human umbilical cord-derived mesenchymal stem cells (HUCMSCs), with a proliferation rate 1.9 times higher than that of cells cultured on tissue culture polystyrene (TCPS) at day 14. Furthermore, it effectively maintained the stem cell characteristics, expressing specific antigens for HUCMSCs. Through qPCR, Western blot, and ELISA experiments, the composite carrier markedly promoted the expression and secretion of key cell factors in HUCMSCs. These results demonstrate that the PET/PDA/dECM composite carrier holds great potential for scaling up MSCs' long-term in vitro cultivation and the production of paracrine factors.

Effects of microenvironment and biological behavior on the paracrine function of stem cells

Mesenchymal stem cells (MSCs), the most well-studied cell type in the field of stem cell therapy, have multi-lineage differentiation and self-renewal potential. MSC-based therapies have been used to treat diverse diseases because of their ability to potently repair tissue and locally restore function. An increasing body of evidence demonstrates that paracrine function is central to the effects of MSC-based therapy. Growth factors, cytokines, chemokines, extracellular matrix components, and extracellular vehicles all contribute to the beneficial effects of MSCs on tissue regeneration and repair. The paracrine substances secreted by MSCs change depending on the tissue microenvironment and biological behavior. In this review, we discuss the bioactive substances secreted by MSCs depending on the microenvironment and biological behavior and their regulatory mechanisms, which explain their potential to treat human diseases, to provide new ideas for further research and clinical cell-free therapy.

Hypoxic Extracellular Matrix Preserves Its Competence after Expansion of Human MSCs under Physiological Hypoxia In Vitro

Tissue-relevant O2 levels are considered as an important tool for the preconditioning of multipotent mesenchymal stromal cells (MSCs) for regenerative medicine needs. The present study investigated the quality and functions of the extracellular matrix (ECM) of MSCs under low O2 levels. Human adipose tissue-derived MSCs were continuously expanded under normoxia (20% O2, N) or "physiological" hypoxia (5% O2, Hyp). Decellularized ECM (dcECM) was prepared. The structure of the dcECM was analyzed using confocal laser and scanning electron microscopy. Collagen, dcECM-N, and dcECM-Hyp were recellularized with MSC-N and further cultured at normoxia. The efficacy of adhesion, spreading, growth, osteogenic potential, and paracrine activity of recellularized MSC-N were evaluated. At low O2, the dcECM showed an increased alignment of fibrillar structures and provided accelerated spreading of MSC-N, indicating increased dcECM-Hyp stiffness. We described O2-dependent "ECM-education" of MSC-N when cultured on dcECM-Hyp. This was manifested as attenuated spontaneous osteo-commitment, increased susceptibility to osteo-induction, and a shift in the paracrine profile. It has been suggested that the ECM after physiological hypoxia is able to ensure the maintenance of a low-commitment state of MSCs. DcECM, which preserves the competence of the natural microenvironment of cells and is capable of "educating" others, appears to be a prospective tool for guiding cell modifications for cell therapy and tissue engineering.

Exosomal miR-17-92 derived from human mesenchymal stem cells promotes wound healing by enhancing angiogenesis and inhibiting endothelial cell ferroptosis

BACKGROUND

Wound healing is a complex and dynamic process that involves a series of cellular and molecular events. Mesenchymal stem cells (MSCs) and their exosomes (MSC-Exos) have crucial functions in cutaneous wound healing. MiR-17-92 is a multifunctional microRNA (miRNA) cluster that plays vital roles in tissue development and tumor angiogenesis. This study aimed to explore the function of miR-17.92 in wound healing as a component of MSC-Exos.

METHODS

Human MSCs were cultured in serum-free medium, and exosomes were collected by ultracentrifugation. The levels of miR-17-92 in MSCs and MSC-Exos were determined by quantitative real-time polymerase chain reaction. MSC-Exos were topically applied to full-thickness excision wounds in the skin of miR-17-92 knockout (KO) and wild-type (WT) mice. The proangiogenic and antiferroptotic effects of MSC-Exos overexpressing miR-17-92 were assayed by evaluating the relative levels of angiogenic and ferroptotic markers.

RESULTS

MiRNA-17-92 was found to be highly expressed in MSCs and enriched in MSC-Exos. Moreover, MSC-Exos promoted the proliferation and migration of human umbilical vein endothelial cells in vitro. KO of miR-17-92 effectively attenuated the promotion of wound healing by MSC-Exos. Furthermore, exosomes derived from miR-17-92-overexpressing human umbilical cord-derived MSCs accelerated cell proliferation, migration, angiogenesis, and enhanced against erastin-induced ferroptosis in vitro. miR-17-92 plays a key role in the protective effects of MSC-Exos against erastin-induced ferroptosis in HUVECs CONCLUSION: These findings suggest that miR-17-92 participates in the repair ability of MSC-Exos and that miR-17-92-overexpressing exosomes may represent a new strategy for cutaneous wound repair.

Three-Dimensional Spheroid Culture of Human Mesenchymal Stem Cells: Offering Therapeutic Advantages and In Vitro Glimpses of the In Vivo State

As invaluable as the standard 2-dimensional (2D) monolayer in vitro cell culture system has been, there is increasing evidence that 3-dimensional (3D) non-adherent conditions are more relevant to the in vivo condition. While one of the criteria for human mesenchymal stem cells (MSCs) has been in vitro plastic adherence, such 2D culture conditions are not representative of in vivo cell-cell and cell-extracellular matrix (ECM) interactions, which may be especially important for this progenitor/stem cell of skeletal and connective tissues. The 3D spheroid, a multicellular aggregate formed under non-adherent 3D in vitro conditions, may be particularly suited as an in vitro method to better understand MSC physiological processes, since expression of ECM and other adhesion proteins are upregulated in such a cell culture system. First used in embryonic stem cell in vitro culture to recapitulate in vivo developmental processes, 3D spheroid culture has grown in popularity as an in vitro method to mimic the 3-dimensionality of the native niche for MSCs within tissues/organs. In this review, we discuss the relevance of the 3D spheroid culture for understanding MSC biology, summarize the biological outcomes reported in the literature based on such this culture condition, as well as contemplate limitations and future considerations in this rapidly evolving and exciting area.

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.

Effect of Cell-Derived Matrices on Growth and Differentiation of Human Wharton's Jelly-Derived Mesenchymal Stem Cells

Cell-derived matrices (CDMs) are scaffolds constructed by decellularization of cellular matrices from different tissues and organs. Since CDMs mimic the extracellular matrices (ECMs) of native tissues, it plays an essential role in the preparation of bioscaffolds. CDM scaffolds from mesenchymal stem cells (MSCs) have been reported to support cell adhesion and proliferation of its own cells. Therefore, in this study we aimed to test if growth of human Wharton's jelly-derived MSCs may be enhanced when cultured on their own CDMs. To do this, MSCs were induced to generate ECM using ascorbic acid. Thus, obtained matrices were decellularized and characterized quantitatively for changes in their biochemical components (total protein, collagen, glycosaminoglycans) and qualitatively for fibronectin, laminin, and collagen (I & IV) by immunostaining. Our results show the retention of essential ECM components in the decellularized WJ-MSC-derived matrix (WJ-CDM). The influence of WJ-CDM on proliferation and differentiation of WJ-MSCs were evaluated by comparing their growth on collagen and fibronectin-only coated plates. A non-coated tissue culture polystyrene plate (TCPS) served as control. Our cell proliferation results show that no significant changes were observed in the proliferation of MSCs when cultured on WJ-CDM as compared to the bio-coated and non-coated cultures. However, gene expression analysis of the differentiation process showed that osteogenic and adipogenic differentiation potential of the WJ-MSCs was significantly increased upon culturing them on WJ-CDM. In conclusion, the present study reveals that the WJ-MSCs cultured on WJ-CDM may augment osteogenic and adipogenic differentiation.

Mechanotransduction in Mesenchymal Stem Cells (MSCs) Differentiation: A Review

Mechanotransduction is the process by which physical force is converted into a biochemical signal that is used in development and physiology; meanwhile, it is intended for the ability of cells to sense and respond to mechanical forces by activating intracellular signals transduction pathways and the relative phenotypic adaptation. It encompasses the role of mechanical stimuli for developmental, morphological characteristics, and biological processes in different organs; the response of cells to mechanically induced force is now also emerging as a major determinant of disease. Due to fluid shear stress caused by blood flowing tangentially across the lumen surface, cells of the cardiovascular system are typically exposed to a variety of mechanotransduction. In the body, tissues are continuously exposed to physical forces ranging from compression to strain, which is caused by fluid pressure and compressive forces. Only lately, though, has the importance of how forces shape stem cell differentiation into lineage-committed cells and how mechanical forces can cause or exacerbate disease besides organizing cells into tissues been acknowledged. Mesenchymal stem cells (MSCs) are potent mediators of cardiac repair which can secret a large array of soluble factors that have been shown to play a huge role in tissue repair. Differentiation of MSCs is required to regulate mechanical factors such as fluid shear stress, mechanical strain, and the rigidity of the extracellular matrix through various signaling pathways for their use in regenerative medicine. In the present review, we highlighted mechanical influences on the differentiation of MSCs and the general factors involved in MSCs differentiation. The purpose of this study is to demonstrate the progress that has been achieved in understanding how MSCs perceive and react to their mechanical environment, as well as to highlight areas where more research has been performed in previous studies to fill in the gaps.

Clues and new evidences in arterial hypertension: unmasking the role of the chloride anion

The present review will focus on the role of chloride anion in cardiovascular disease, with special emphasis in the development of hypertensive disease and vascular inflammation. It is known that acute and chronic overload of sodium chloride increase blood pressure and have pro-inflammatory and pro-fibrotic effects on different target organs, but it is unknown how chloride may influence these processes. Chloride anion is the predominant anion in the extracellular fluid and its intracellular concentration is dynamically regulated. As the queen of the electrolytes, it is of crucial importance to understand the physiological mechanisms that regulate the cellular handling of this anion including the different transporters and cellular chloride channels, which exert a variety of functions, such as regulation of cellular proliferation, differentiation, migration, apoptosis, intracellular pH and cellular redox state. In this article, we will also review the relationship between dietary, serum and intracellular chloride and how these different sources of chloride in the organism are affected in hypertension and their impact on cardiovascular disease. Additionally, we will discuss the approach of potential strategies that affect chloride handling and its potential effect on cardiovascular system, including pharmacological blockade of chloride channels and non-pharmacological interventions by replacing chloride by another anion.

Construction of extracellular matrix-based 3D hydrogel and its effects on cardiomyocytes

Some discoveries resulted from 2-dimensional (2D) cultured cardiac cells have been disqualified in animal testing and later clinical trials. Extracellular matrix (ECM) plays a vital role in cardiac homeostasis, cardiac ECM (cECM)-based 3D cell cultures can mimics the physiological and pathological conditions in vivo closely, it is hopeful of addressing this challenge. Construction of cECM-based 3-dimensional (3D) hydrogel (cECM3DH) and its effects on cell behaviors were studied here. The results indicated that cellular compartments could be efficiently removed from heart tissue via sodium dodecyl sulfonate (SDS)- and Triton X-100-mediated decellularization, remaining the natural fibrous network structure and major proteins. 3D hydrogel consisted of 1 × 107 cells/mL cells and 75% cECM could promote the proliferation and anti-apoptosis ability of human embryonic kidney (HEK)-293T cells. 0.25% trypsin or 0.20% collagenase was suitable to retrieve these cells from 3D hydrogel for further researches. Compared with 2D culture system, cECM3DH could significantly increase the proportion of GATA 4+ cardiomyocytes (CMs) derived from heart tissue of neonatal mouse or induced differentiation of embryonic stem cells (ESCs) (P < 0.05) The expression levels of mature genes including cTnT, JCN, CaV1.2, MYL2, CASQ2, NCX1, and Cx43 of these CMs in adult pig cECM-based 3D hydrogel (APcECM3DH) were significantly higher than that in 2D culture system and in newborn piglet cECM-based 3D hydrogel (NPcECM3DH), respectively (P < 0.05). Therefore, cECM3DH supports the generation of primary CMs and ESC-derived CMs, APcECM3DH was more conducive to promoting CM maturation, which contributes to building 3D model for pathogenesis exploration, drug screening, and regenerative medicine of heart diseases.

Modulation of Inherent Niches in 3D Multicellular MSC Spheroids Reconfigures Metabolism and Enhances Therapeutic Potential

Multicellular spheroids show three-dimensional (3D) organization with extensive cell–cell and cell–extracellular matrix interactions. Owing to their native tissue-mimicking characteristics, mesenchymal stem cell (MSC) spheroids are considered promising as implantable therapeutics for stem cell therapy. Herein, we aim to further enhance their therapeutic potential by tuning the cultivation parameters and thus the inherent niche of 3D MSC spheroids. Significantly increased expression of multiple pro-regenerative paracrine signaling molecules and immunomodulatory factors by MSCs was observed after optimizing the conditions for spheroid culture. Moreover, these alterations in cellular behaviors may be associated with not only the hypoxic niche developed in the spheroid core but also with the metabolic reconfiguration of MSCs. The present study provides efficient methods for manipulating the therapeutic capacity of 3D MSC spheroids, thus laying solid foundations for future development and clinical application of spheroid-based MSC therapy for regenerative medicine.

Techniques for increasing the yield of stem cell-derived exosomes: what factors may be involved?

Exosomes are nano-scale extracellular vesicles secreted by cells and constitute an important part in the cell-cell communication. The main contents of the exosomes include proteins, microRNAs, and lipids. The mechanism and safety of stem cell-derived exosomes have rendered them a promising therapeutic strategy for regenerative medicine. Nevertheless, limited yield has restrained full explication of their functions and clinical applications To address this, various attempts have been made to explore the up- and down-stream manipulations in a bid to increase the production of exosomes. This review has recapitulated factors which may influence the yield of stem cell-derived exosomes, including selection and culture of stem cells, isolation and preservation of the exosomes, and development of artificial exosomes.

Co-delivery of fibrin-laminin hydrogel with mesenchymal stem cell spheroids supports skeletal muscle regeneration following trauma

Volumetric muscle loss (VML) is traumatic or surgical loss of skeletal muscle with resultant functional impairment. Skeletal muscle's innate capacity for regeneration is lost with VML due to a critical loss of stem cells, extracellular matrix, and neuromuscular junctions. Consequences of VML include permanent disability or delayed amputations of the affected limb. Currently, a successful clinical therapy has not been identified. Mesenchymal stem cells (MSCs) possess regenerative and immunomodulatory properties and their three-dimensional aggregation can further enhance therapeutic efficacy. In this study, MSC aggregation into spheroids was optimized in vitro based on cellular viability, spheroid size, and trophic factor secretion. The regenerative potential of the optimized MSC spheroid therapy was then investigated in a murine model of VML injury. Experimental groups included an untreated VML injury control, intramuscular injection of MSC spheroids, and MSC spheroids encapsulated in a fibrin-laminin hydrogel. Compared to the untreated VML group, the spheroid encapsulating hydrogel group enhanced myogenic marker (i.e., MyoD and myogenin) protein expression, improved muscle mass, increased presence of centrally nucleated myofibers as well as small fibers (<500 μm² ), modulated pro- and anti-inflammatory macrophage marker expression (i.e., iNOS and Arginase), and increased the presence of CD146⁺ pericytes and CD31⁺ endothelial cells in the VML injured muscles. Future studies will evaluate the extent of functional recovery with the spheroid encapsulating hydrogel therapy.

Bio-instructive hydrogel expands the paracrine potency of mesenchymal stem cells

The therapeutic efficacy of clinically applied mesenchymal stromal cells (MSCs) is limited due to their injection into harshin vivoenvironments, resulting in the significant loss of their secretory function upon transplantation. A potential strategy for preserving their full therapeutic potential is encapsulation of MSCs in a specialized protective microenvironment, for example hydrogels. However, commonly used injectable hydrogels for cell delivery fail to provide the bio-instructive cues needed to sustain and stimulate cellular therapeutic functions. Here we introduce a customizable collagen I-hyaluronic acid (COL-HA)-based hydrogel platform for the encapsulation of MSCs. Cells encapsulated within COL-HA showed a significant expansion of their secretory profile compared to MSCs cultured in standard (2D) cell culture dishes or encapsulated in other hydrogels. Functionalization of the COL-HA backbone with thiol-modified glycoproteins such as laminin led to further changes in the paracrine profile of MSCs. In depth profiling of more than 250 proteins revealed an expanded secretion profile of proangiogenic, neuroprotective and immunomodulatory paracrine factors in COL-HA-encapsulated MSCs with a predicted augmented pro-angiogenic potential. This was confirmed by increased capillary network formation of endothelial cells stimulated by conditioned media from COL-HA-encapsulated MSCs. Our findings suggest that encapsulation of therapeutic cells in a protective COL-HA hydrogel layer provides the necessary bio-instructive cues to maintain and direct their therapeutic potential. Our customizable hydrogel combines bioactivity and clinically applicable properties such as injectability, on-demand polymerization and tissue-specific elasticity, all features that will support and improve the ability to successfully deliver functional MSCs into patients.

Comprehensive Profiling of Secretome Formulations from Fetal- and Perinatal Human Amniotic Fluid Stem Cells

We previously reported that c-KIT+ human amniotic-fluid derived stem cells obtained from leftover samples of routine II trimester prenatal diagnosis (fetal hAFS) are endowed with regenerative paracrine potential driving pro-survival, anti-fibrotic and proliferative effects. hAFS may also be isolated from III trimester clinical waste samples during scheduled C-sections (perinatal hAFS), thus offering a more easily accessible alternative when compared to fetal hAFS. Nonetheless, little is known about the paracrine profile of perinatal hAFS. Here we provide a detailed characterization of the hAFS total secretome (i.e., the entirety of soluble paracrine factors released by cells in the conditioned medium, hAFS-CM) and the extracellular vesicles (hAFS-EVs) within it, from II trimester fetal- versus III trimester perinatal cells. Fetal- and perinatal hAFS were characterized and subject to hypoxic preconditioning to enhance their paracrine potential. hAFS-CM and hAFS-EV formulations were analyzed for protein and chemokine/cytokine content, and the EV cargo was further investigated by RNA sequencing. The phenotype of fetal- and perinatal hAFS, along with their corresponding secretome formulations, overlapped; yet, fetal hAFS showed immature oxidative phosphorylation activity when compared to perinatal ones. The profiling of their paracrine cargo revealed some differences according to gestational stage and hypoxic preconditioning. Both cell sources provided formulations enriched with neurotrophic, immunomodulatory, anti-fibrotic and endothelial stimulating factors, and the immature fetal hAFS secretome was defined by a more pronounced pro-vasculogenic, regenerative, pro-resolving and anti-aging profile. Small RNA profiling showed microRNA enrichment in both fetal- and perinatal hAFS-EV cargo, with a stably- expressed pro-resolving core as a reference molecular signature. Here we confirm that hAFS represents an appealing source of regenerative paracrine factors; the selection of either fetal or perinatal hAFS secretome formulations for future paracrine therapy should be evaluated considering the specific clinical scenario.

Nidogen-1 Mitigates Ischemia and Promotes Tissue Survival and Regeneration

Ischemia impacts multiple organ systems and is the major cause of morbidity and mortality in the developed world. Ischemia disrupts tissue homeostasis, driving cell death, and damages tissue structure integrity. Strategies to heal organs, like the infarcted heart, or to replace cells, as done in pancreatic islet β-cell transplantations, are often hindered by ischemic conditions. Here, it is discovered that the basement membrane glycoprotein nidogen-1 attenuates the apoptotic effect of hypoxia in cardiomyocytes and pancreatic β-cells via the αvβ3 integrin and beneficially modulates immune responses in vitro. It is shown that nidogen-1 significantly increases heart function and angiogenesis, while reducing fibrosis, in a mouse postmyocardial infarction model. These results demonstrate the protective and regenerative potential of nidogen-1 in ischemic conditions.

Post-calving umbilical cord tissue offcut: A potential source for the isolation of bovine mesenchymal stem cells

Background and Aim:

Veterinary health care is an emergent area in animal sciences and innovative therapeutic approaches happen to be imperative in the present days. In view of the importance of cattle health and production, it is necessary to take up contemporary approach of stem cell therapy in this sector also. This study aimed to standardize an explant culture method of bovine umbilical tissue offcut to isolate mesenchymal stem cells (MSCs) because considerable efforts are required for ensuring easy accessibility and availability of MSCs in bulk quantity, as well as in establishing and characterizing the cell lines.

Materials and Methods:

The umbilical cord (UC) tissue matrix offcut was collected after calving. A simplified in vitro cell isolation technique was followed to collect the emerged out cells from the explants of UC. Further, we expanded these isolated cells in vitro, observed its growth kinetics, and characterized to confirm as per the criterion of bovine MSCs.

Results:

A considerable exponential growth rate of the UC-derived cells was noticed. In addition to their confirmation as MSCs, the cells also exhibited plastic adherent property and maintained the spindle-shaped morphology throughout the in vitro culture. The cultured cells were found positive MSC-specific surface markers CD105, CD90, and CD73 and were negative for hematopoietic cell marker CD45. Cytochemical studies revealed the ability of the cells to differentiate into osteogenic, chondrogenic, and adipogenic lineages.

Conclusion:

This simplified method of isolation and culture of bovine multipotent MSCs from the UC offcut collected after calving could be extrapolated for the greater availability of the cells for prospective therapeutic applications.

[Effect of demineralized bone matrix modified by laminin α4 chain functional peptide on H-type angiogenesis and osteogenesis to promote bone defect repair]

Objective

Based on the cell-extracellular matrix adhesion theory in selective cell retention (SCR) technology, demineralized bone matrix (DBM) modified by simplified polypeptide surface was designed to promote both bone regeneration and angiogenesis.

Methods

Functional peptide of α4 chains of laminin protein (LNα4), cyclic RGDfK (cRGD), and collagen-binding domain (CBD) peptides were selected. CBD-LNα4-cRGD peptide was synthesized in solid phase and modified on DBM to construct DBM/CBD-LNα4-cRGD scaffold (DBM/LN). Firstly, scanning electron microscope and laser scanning confocal microscope were used to examine the characteristics and stability of the modified scaffold. Then, the adhesion, proliferation, and tube formation properties of CBD-LNα4-cRGD peptide on endothelial progenitor cells (EPCs) were detected, respectively. Western blot method was used to verify the molecular mechanism affecting EPCs. Finally, 24 10-week-old male C57 mice were used to establish a 2-mm-length defect of femoral bone model. DBM/LN and DBM scaffolds after SCR treatment were used to repair bone defects in DBM/LN group ( n=12) and DBM group ( n=12), respectively. At 8 weeks after operation, the angiogenesis and bone regeneration ability of DBM/LN scaffolds were evaluated by X-ray film, Micro-CT, angiography, histology, and immunofluorescence staining [CD31, endomucin (Emcn), Ki67].

Results

Material related tests showed that the surface of DBM/LN scaffold was rougher than DBM scaffold, but the pore diameter did not change significantly ( t=0.218, P=0.835). After SCR treatment, DBM/LN scaffold was still stable and effective. Compared with DBM scaffold, DBM/LN scaffold could adhere to more EPCs after the surface modification of CBD-LNα4-cRGD ( P<0.05), and the proliferation rate and tube formation ability increased. Western blot analysis showed that the relative expressions of VEGF, phosphorylated FAK (p-FAK), and phosphorylated ERK1/2 (p-ERK1/2) proteins were higher in DBM/LN than in DBM ( P<0.05). In the femoral bone defect model of mice, it was found that mice implanted with DBM/LN scaffold had stronger angiogenesis and bone regeneration capacity ( P<0.05), and the number of CD31 ^hiEmcn ^hi cells increased significantly ( P<0.05).

Conclusion

DBM/LN scaffold can promote the adhesion of EPCs. Importantly, it can significantly promote the generation of H-type vessels and realize the effective coupling between angiogenesis and bone regeneration in bone defect repair.

Epigenetic Regulation in Mesenchymal Stem Cell Aging and Differentiation and Osteoporosis

Mesenchymal stem cells (MSCs) are a reliable source for cell-based regenerative medicine owing to their multipotency and biological functions. However, aging-induced systemic homeostasis disorders in vivo and cell culture passaging in vitro induce a functional decline of MSCs, switching MSCs to a senescent status with impaired self-renewal capacity and biased differentiation tendency. MSC functional decline accounts for the pathogenesis of many diseases and, more importantly, limits the large-scale applications of MSCs in regenerative medicine. Growing evidence implies that epigenetic mechanisms are a critical regulator of the differentiation programs for cell fate and are subject to changes during aging. Thus, we here review epigenetic dysregulations that contribute to MSC aging and osteoporosis. Comprehending detailed epigenetic mechanisms could provide us with a novel horizon for dissecting MSC-related pathogenesis and further optimizing MSC-mediated regenerative therapies.

Human Placental MSC-Secreted IL-1β Enhances Neutrophil Bactericidal Functions during Hypervirulent Klebsiella Infection

Hypervirulent Klebsiella pneumoniae (hvKP) causes severe infections even in healthy individuals by escaping surveillance and killing from polymorphonuclear neutrophils (PMNs), the first-line leukocytes in bacterial infections; moreover, the emergence of multidrug-resistant strains further limits treatment options. We therefore assess whether multilineage mesenchymal stem cells (MSCs), best known for immunomodulation toward T cells, could be therapeutic for highly virulent bacterial infections via modulation of PMNs. We find that both bone marrow MSCs and placental MSCs (PMSCs) preserve in vitro PMN survival, but only PMSCs significantly enhance multiple PMN bactericidal functions, including phagocytosis, through secretion of interleukin-1β (IL-1β). PMSC treatment of hvKP-infected mice suppresses T and natural killer (NK) cell responses as expected but can preferentially recruit PMNs and enhance antibacterial functions to allow for disease survival; IL-1β knockdown in PMSCs significantly decreases hvKP clearance, worsening survival and resulting in 100% lethality. Our data strongly implicate the possible use of PMSCs for infections of PMN-resistant hvKP strains.

Mechanical Cues Regulating Proangiogenic Potential of Human Mesenchymal Stem Cells through YAP-Mediated Mechanosensing

Stem cells secrete trophic factors that induce angiogenesis. These soluble factors are promising candidates for stem cell-based therapies, especially for cardiovascular diseases. Mechanical stimuli and biophysical factors presented in the stem cell microenvironment play important roles in guiding their behaviors. However, the complex interplay and precise role of these cues in directing pro-angiogenic signaling remain unclear. Here, a platform is designed using gelatin methacryloyl hydrogels with tunable rigidity and a dynamic mechanical compression bioreactor to evaluate the influence of matrix rigidity and mechanical stimuli on the secretion of pro-angiogenic factors from human mesenchymal stem cells (hMSCs). Cells cultured in matrices mimicking mechanical elasticity of bone tissues in vivo show elevated secretion of vascular endothelial growth factor (VEGF), one of representative signaling proteins promoting angiogenesis, as well as increased vascularization of human umbilical vein endothelial cells (HUVECs) with a supplement of conditioned media from hMSCs cultured across different conditions. When hMSCs are cultured in matrices stimulated with a range of cyclic compressions, increased VEGF secretion is observed with increasing mechanical strains, which is also in line with the enhanced tubulogenesis of HUVECs. Moreover, it is demonstrated that matrix stiffness and cyclic compression modulate secretion of pro-angiogenic molecules from hMSCs through yes-associated protein activity.

Extracellular vesicles derived from human adipose-derived stem cells promote the exogenous angiogenesis of fat grafts via the let-7/AGO1/VEGF signalling pathway

Extracellular vesicles (EVs) derived from human adipose-derived stem cells (hADSCs) possess the proangiogenic potential for ischaemic diseases. Thus, our study aimed to evaluate the therapeutic effects of hADSC-EVs on fat grafting and explore the mechanism of hADSC-EVs promoting angiogenesis. The EVs released by hADSCs incubated under normal or hypoxic conditions were employed to supplement fat grafting in a nude mouse model. The proliferation, migration, tube formation and vascular endothelial growth factor (VEGF) secretion of vascular endothelial cells co-cultured with two kinds of hADSC-EVs were analysed. MicroRNA sequencing was performed to reveal the species and content of microRNAs in hADSC-EVs, the key microRNAs were blocked, and their effect in promoting angiogenesis was detected via above protocols as a reverse proof. The results demonstrate that hADSC-EVs could improve the survival of fat grafts by promoting exogenous angiogenesis and enhance the proliferation, migration, tube formation and VEGF secretion of vascular endothelial cells. In addition, the pro-angiogenic effect of hADSC-EVs in vivo and vitro could be enhanced by hypoxic pre-treatment. We found that the let-7 family, a kind of hypoxic-related microRNA, is enriched in hypoxic hADSC-EVs that contribute to angiogenesis via the let-7/argonaute 1 (AGO1)/VEGF signalling pathway.

Message in a Bottle: Upgrading Cardiac Repair into Rejuvenation

Ischaemic cardiac disease is associated with a loss of cardiomyocytes and an intrinsic lack of myocardial renewal. Recent work has shown that the heart retains limited cardiomyocyte proliferation, which remains inefficient when facing pathological conditions. While broadly active in the neonatal mammalian heart, this mechanism becomes quiescent soon after birth, suggesting loss of regenerative potential with maturation into adulthood. A key question is whether this temporary regenerative window can be enhanced via appropriate stimulation and further extended. Recently the search for novel therapeutic approaches for heart disease has centred on stem cell biology. The “paracrine effect” has been proposed as a promising strategy to boost endogenous reparative and regenerative mechanisms from within the cardiac tissue by exploiting the modulatory potential of soluble stem cell-secreted factors. As such, growing interest has been specifically addressed towards stem/progenitor cell-secreted extracellular vesicles (EVs), which can be easily isolated in vitro from cell-conditioned medium. This review will provide a comprehensive overview of the current paradigm on cardiac repair and regeneration, with a specific focus on the role and mechanism(s) of paracrine action of EVs from cardiac stromal progenitors as compared to exogenous stem cells in order to discuss the optimal choice for future therapy. In addition, the challenges to overcoming translational EV biology from bench to bedside for future cardiac regenerative medicine will be discussed.

Paracrine Mechanisms Involved in Mesenchymal Stem Cell Differentiation into Cardiomyocytes

Cardiovascular Disease (CVD) is one of the world-wide healthcare problem that involves the heart or blood vessels. CVD includes myocardial infarction and coronary artery diseases (CAD). Dysfunctional myocardial cells are leading causes of low cardiac output or ventricular dysfunction after cardiac arrest and may contribute to the progression of CVD which could not generate new cardiomyocytes in human adult heart. The mesenchymal stem cells (MSCs) which are present in adult marrow can self-renew and have the capacity of differentiation into multiple types of cells including cardiomyocytes. Recent biochemical analyses greatly revealed that several regulators of MSCs, such as HGF, PDGF, Wnt, and Notch-1 signaling pathways have been shown to be involved in the proliferation and differentiation into cardiomyocytes. Preclinical studies are paving the way for further applications of MSCs in the repair of myocardial infarction. In this study, we discuss and summarize the paracrine mechanisms involved in MSCs differentiation into cardiomyocytes.

β-Integrin mediates LPS-induced coelomocyte apoptosis in sea cucumber Apostichopus japonicus via the integrin/FAK/caspase-3 signaling pathway

Lipopolysaccharides (LPS) can induce the apoptosis of coelomocytes in Apostichopus japonicus (A. japonicus), and β-integrin serves as an apoptotic inhibitor during this process. However, the underlying mechanism in invertebrates is largely unknown. Integrin/focal adhesion kinase (FAK) signaling pathway modulates the apoptosis in vertebrates. In this study, a novel FAK was identified from A. japonicus (designated as AjFAK) by β-integrin (designated as AjITGB) -mediated GST-pull down assay. This interaction was further validated in the LPS-exposed coelomocytes through co-immunoprecipitation and immunofluorescence analyses. To investigate the functional role of AjFAK in AjITGB-mediated coelomocyte apoptosis, we cloned the full-length cDNA of AjFAK and characterized its relationship with AjITGB through real-time PCR. The mRNA expression levels of AjFAK exhibited consistent expression patterns with those of AjITGB in our previous work with 0.48- and 0.22-fold decreases at 12 and 96 h in LPS-exposed coelomocytes and in Vibrio splendidus challenged sea cucumber, respectively. Moreover, the expression level of AjFAK decreased to 0.35-fold in AjITGB knockdown treatment by specific small interference RNA (siRNA). We further performed an assay for the apoptotic rate of coelomocytes in AjITGB, AjFAK, and AjITGB/AjFAK silencing conditions and found that their apoptotic percentages increased to 26%, 25%, and 30%, respectively, compared with those of the control. Finally, the expression levels of four caspases from A. japonicus were also investigated to determine the apoptotic effector. After AjITGB or AjFAK was silenced, the mRNA levels of caspase-3 were 6.6-fold and 2.5-fold higher than those of the control, respectively. In addition, the enzymatic activity of caspase-3 was enhanced to 1.82- and 1.79-fold that of the control in the two groups. However, no significant changes were detected in caspase-2/6/8. All our results supported that β-integrin mediated the LPS-induced coelomocyte apoptosis in sea cucumber via the integrin/FAK/caspase-3 signaling pathway.

The effect of mesenchymal stem cell-secreted factors on airway epithelial repair

Aim: This study was aimed to investigate the effect of mesenchymal stem cell (MSC)-secreted factors on airway repair. Materials & methods: An indirect in vitro coculture model of injured airway epithelium explant with MSCs was developed. LC–MS/MS analysis was performed to determine factors secreted by MSCs and their involvement in epithelium repair was evaluated by histopathological assessment. Results: The identification of 54 of MSC proteins of which 44 of them were secretory/extracellular proteins. 43 of the secreted proteins were found to be involved in accelerating airway epithelium repair by stimulating the migratory, proliferative and differentiation abilities of the endogenous repair mechanisms. MSC-secreted proteins also initiated epithelial–mesenchymal transition process during early repair. Conclusion: MSC-secreted factors accelerated airway epithelial repair by stimulating the endogenous reparative and regenerative ability of lung cells.

Engineered Mesenchymal Stem Cells Expressing Stromal Cell-derived Factor-1 Improve Erectile Dysfunction in Streptozotocin-Induced Diabetic Rats

Effective therapies for erectile dysfunction (ED) associated with diabetes mellitus (DM) are needed. In this study, the effects of stromal cell-derived factor-1 (SDF-1)-expressing engineered mesenchymal stem cells (SDF-1 eMSCs) and the relevant mechanisms in the corpus cavernosum of a streptozotocin (STZ)-induced DM ED rat model were evaluated. In a randomized controlled trial, Sprague–Dawley (SD) rats (n = 48) were divided into four groups (n = 12/group): Normal (control), DM ED (diabetes induced by STZ), DM ED + BM-MSC (treated with bone marrow [BM]-derived MSCs), and DM ED + SDF-1 eMSC (treated with SDF-1-expressing BM-MSCs). After four weeks, intracavernosal pressure (ICP), an indicator of erectile function, was 0.75 ± 0.07 in the normal group, 0.27 ± 0.08 in the DM ED group, 0.42 ± 0.11 in the DM ED + BM-MSC group, and 0.58 ± 0.11 in the DM ED + SDF-1 eMSC group. BM-MSCs, especially SDF-1 eMSCs, improved ED (p < 0.05). SDF-1 eMSC treatment improved the smooth muscle content in the corpus cavernosum (p < 0.05). As SDF-1 expression increased, ED recovery improved. In the SDF-1 eMSC group, levels of neuronal nitric oxide synthase (nNOS) and phosphorylated endothelial NOS (p-eNOS) were higher than those in other groups (p < 0.05). In addition, high stromal cell-derived factor-1 (SDF-1) expression was associated with increased vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in DM ED rats (p < 0.05). Higher levels of phosphorylated protein kinase B (p-AKT)/protein kinase B (AKT) (p < 0.05) and B-cell lymphoma-2 (Bcl-2) and lower levels of the apoptosis factors Bcl2-associated x (Bax) and caspase-3 were observed in the MSC-treated group than in the DM ED group (p < 0.05). SDF-1 eMSCs showed beneficial effects on recovery from erectile function.

Promoting hepatogenic differentiation of human mesenchymal stem cells using a novel laminin-containing gelatin cryogel scaffold

Liver transplantation is the only definitive treatment currently available for acute and chronic liver failure. However, this approach has been restricted by complications including rejection and infection. Tissue engineering approaches using stem cell-derived functional hepatic cells offer a potential alternative. Using biologically compatible scaffolds is an important complementary key to achieve optimal construct for hepatic replacement. In the present study, to optimize the differentiation of human adipose-derived mesenchymal stem cells (ADMSCs) toward hepatocyte-like cells, a previously described gelatin cryogel was optimized and improved by laminin, the major component of basal lamina. The ADMSCs seeded on the scaffold displayed increased attachment in the presence of laminin and the MTT assay showed good compatibility for cell proliferation. The differentiation of stem cells were evaluated using glycogen staining, urea secretion measurement, hepatocyte specific cell surface analysis and gene expression analysis. The results of tests indicated that laminin protein and gelatin cryogel 3D scaffold, each on its own, enhanced hepatogenic differentiation of ADMSCs. However, when laminin immobilized on the gelatin cryogel surface, the differentiation was promoted significantly and the resulting cells showed striking similarity to HepG2 in terms of expressing studied hepatocyte markers.