Mesenchymal stem cell migration is regulated by fibronectin through α5β1-integrin-mediated activation of PDGFR-β and potentiation of growth factor signals

Self-assembled biomimetic Nano-Matrix for stem cell anchorage

Mesenchymal stem cells (MSCs) have been widely applied in biomedicine due to their ability to differentiate into many different cell types and their ability to synthesize a broad spectrum of growth factors and cytokines that directly and indirectly influence other cells in their vicinity. To guide MSC infiltration to a bone fracture site, we developed a novel self-assembled Nano-Matrix which can be used as an injectable scaffold to repair bone fractures. The Nano-Matrix is formed by Janus base nanotubes (JBNTs) and fibronectin (FN). JBNTs are nucleobase-derived nanotubes mimicking collagen fibers, and FN is one of the cell adhesive glycoproteins which is responsible for cell-extracellular matrix interactions and guides stem cell migration and differentiation to desired cells types. Here, we demonstrated the successful fabrication and characterization of the JBNT/FN Nano-Matrix as well as its excellent bioactivity that encouraged human MSC migration and adhesion. This work lays a solid foundation for using the Nano-Matrix as an injectable approach to improve MSC retention and function during bone fracture healing.

Endothelial progenitor cells promote viability and nerve regenerative ability of mesenchymal stem cells through PDGF-BB/PDGFR-β signaling

Denervation-induced erectile dysfunction (ED) is a prevailing health problem. Our previous study revealed that endothelial progenitor cells (EPCs) promoted the effect of mesenchymal stem cells (MSCs) on restoration of denervation-induced ED in rats. However, underling mechanisms are still largely elusive. In this study, EPCs and MSCs were co-cultured and resorted to co-EPCs and co-MSCs. EPCs-derived paracrine factors containing PDGF-BB (platelet-derived growth factor) were detected, and MSCs were pre-treated with PDGF-BB, while co-MSCs were pre-treated with PDGFR inhibitor AG1296. Either viability or nerve regenerative ability of MSCs was evaluated. In addition, inhibition of either PI3K/Akt or MEK/Erk pathway was performed to evaluate the role of PI3K/Akt and MEK/Erk pathway in PDGF-BB-induced viability of MSCs. The results revealed that PDGF-BB significantly increased the proportion of PDGFR-β⁺ MSCs, and promoted both in-vitro and in-vivo viability, as well as nerve regenerative capacity and erectile function restoration of MSCs in rats. Inhibition of PI3K/Akt, MEK/Erk pathway or mTOR led to decrease of PDGF-BB/PDGFR-β induced viability of MSCs. To our knowledge, our study first demonstrates that EPCs promote viability and potential nerve regenerative ability of MSCs through PDGF-BB/PDGFR-β signaling and its downstream PI3K/Akt and MEK/Erk pathways. mTOR acts as a co-mediator in PI3K/Akt and MEK/Erk pathways.

Modulation of Human Neutrophil Peptides on P. aeruginosa Killing, Epithelial Cell Inflammation and Mesenchymal Stromal Cell Secretome Profiles

Objective

Neutrophil infiltration and release of the abundant human neutrophil peptides (HNP) are a common clinical feature in critically ill patients. We tested a hypothesis that different cell types respond to HNP differently in lung microenvironment that may influence the host responses.

Methods

Plasma concentrations of HNP were measured in healthy volunteers and patients with sepsis. Cells including the bacteria P. aeruginosa, human lung epithelial cells and mesenchymal stromal cells (MSCs) were exposed to various concentrations of HNP. Bacterial killing, epithelial cell inflammation, MSC adhesion and behaviours were examined after HNP stimulation.

Results

Incubation of P. aeruginosa or stimulation of human lung epithelial cells with HNP resulted in bacterial killing or IL-8 production at a dose of 50 μg/mL, while MSC adhesion and alternations of secretome profiles took place after HNP stimulation at a dose of 10 μg/mL. The secretome profile changes were characterized by increased release of the IL-6 family members such as C-reactive protein (CRP), leukemia inhibitory factor (LIF) and interleukin (IL-11), and first apoptosis signal (FAS) and platelet-derived growth factor-AA as compared to a vehicle control group.

Conclusion

Stimulation of MSCs with HNP resulted in changes of secretome profiles at 5-fold lower concentration than that required for bacterial killing and lung epithelial inflammation. This undisclosed risk factor of HNP in lung environment should be taken into consideration when MSCs are applied as cell therapy in inflammatory lung diseases.

Comparative adhesive and migratory properties of mesenchymal stem cells from different tissues

BACKGROUND

Mesenchymal stem cells (MSC) are used in therapy, often by injection into the blood.

OBJECTIVE

We aimed to compare the adhesive and migratory properties of MSC from umbilical cords (UCMSC), bone marrow (BMMSC) or trabecular bone (TBMSC), which might influence delivery to injured tissue.

METHODS

MSC were perfused through glass capillaries coated with matrix proteins, collagen or fibronectin, or albumin. Adherent cells were counted microscopically and their spreading analysed over time. MSC migration through 8 μm pore filters coated with the same proteins was analysed.

RESULTS

The number of MSC adhering to collagen was greater than fibronectin, decreased as wall shear rate increased from 17 to 70 s-1, and was in the order UCMSC>BMMSC>TBMSC. Conversely, spreading was more effective on fibronectin and was in the order BMMSC>TBMSC≥UCMSC. Migration was promoted by coating the lower surface of filters with either matrix protein, with UCMSC migrating more efficiently than BMMSC.

CONCLUSIONS

MSC show origin-dependent variations in their efficiency of capture from flow and subsequent spreading or ability to migrate on matrix proteins. UCMSC showed most efficient capture from flow, which was followed by less spreading, but more rapid migration. These responses might be associated with more effective delivery from the circulation into damaged tissue.

Characterization of progenitor/stem cell population from human dental socket and their multidifferentiation potential

Dental stem cells have many applications in medicine, dentistry and stem cell biology in general due to their easy accessibility and low morbidity. A common surgical manoeuvre after a tooth extraction is the dental socket curettage which is necessary to clean the alveolus and favour alveolar bone healing. This procedure can cause very low morbidity compared to bone marrow collection procedures and the collected material is normally discarded. In order to investigate if the tissue obtained by dental socket curettage after a tooth extraction was a feasible alternative source to isolate human stem cells, we isolated and characterized two different stem cell populations based on STRO-1 and CD146 expression. We were able to collect and grow cells from dental socket of vital and non-vital teeth. Both populations were proliferative, clonogenic and expressed STRO-1, CD146, CD90, NG2, PDGFR-β, which are markers found in stem cells, presented in vitro multiline-differentiation into osteogenic, chondrogenic, and adipogenic tissue, and in vivo transplanted cells formed mineralized tissue. Interestingly, STRO-1⁺ clonogenic cells presented better multidifferentiation than CD146⁺ cells. Our results showed that mesenchymal stem cells can be isolated from the tiny tissue collected by dental socket curettage after vital and non-vital tooth extraction and suggest that STRO-1 is an important marker to be used to sort cells with multidifferentiation capacity.

A hybrid multiscale model for investigating tumor angiogenesis and its response to cell-based therapy

Angiogenesis, a formation of blood vessels from an existing vasculature, plays a key role in tumor growth and its progression into cancer. The lining of blood vessels consists of endothelial cells (ECs) which proliferate and migrate, allowing the capillaries to sprout towards the tumor to deliver the needed oxygen. Various treatments aiming to suppress or even inhibit angiogenesis have been explored. Mesenchymal stem cells (MSCs) have recently been undergoing development in cell-based therapy for cancer due to their ability to migrate towards the capillaries and induce the apoptosis of the ECs, causing capillary degeneration. However, further investigations in this direction are needed as it is usually difficult to preclinically assess the efficacy of such therapy. We develop a hybrid multiscale model that integrates molecular, cellular, tissue and extracellular components of tumor system to investigate angiogenesis and tumor growth under MSC-mediated therapy. Our simulations produce angiogenesis and vascular tumor growth profiles as observed in the experiments. Furthermore, the simulations show that the effectiveness of MSCs in inducing EC apoptosis is density dependent and its full effect is reached within several days after MSCs application. Quantitative agreements with experimental data indicate the predictive potential of our model for evaluating the efficacy of cell-based therapies targeting angiogenesis.

Cancer Conditioned Medium Modulates Functional and Phenotypic Properties of Human Decidua Parietalis Mesenchymal Stem/Stromal Cells

Background

Mesenchymal Stem/Stromal Cells (MSCs) from the decidua parietalis (DPMSCs) of human term placenta express several molecules with important biological and immunological properties. DPMSCs induce natural killer cell expression of inflammatory receptors and their cytotoxic activity against cancer cells. These properties make DPMSCs promising therapeutical agent for cancer. The successful development of MSCs as an anti-cancer therapeutic cells rely on their ability to function in a hostile inflammatory and oxidative stress cancer environment. Here, we studied the effects of conditioned medium obtained from the culture of breast cancer cells (CMMDA-231) on the functional and phenotypic properties of DPMSCs.

Methods

DPMSCs were cultured with CMMDA-231 and important functions of DPMSCs were measured. The effect of CMMDA-231 on DPMSC expression of several genes with different functions was also evaluated.

Results

DPMSCs were able to function in response to CMMDA-231, but with reduced proliferative and adhesive potentials. Preconditioning of DPMSCs with CMMDA-231 enhanced their adhesion while reducing their invasion. In addition, CMMDA-231 modulated DPMSC expression of many genes with various functional (i.e., proliferation, adhesion, and invasion) properties. DPMSCs also showed increased expression of genes with anti-cancer property.

Conclusion

These data show the ability of DPMSCs to survive and function in cancer environment. In addition, preconditioning of DPMSCs with CMMDA-231 enhanced their anti-cancer properties and thus demonstrating their potential as an anti-cancer therapeutic agent. However, future studies are essential to reveal the mechanism underlying the effects of MDA-231 on DPMSC functional activities and also to confirm the anti-cancer therapeutic potential of DPMSCs.

Perlecan regulates pericyte dynamics in the maintenance and repair of the blood-brain barrier

Ischemic stroke causes blood-brain barrier (BBB) breakdown due to significant damage to the integrity of BBB components. Recent studies have highlighted the importance of pericytes in the repair process of BBB functions triggered by PDGFRβ up-regulation. Here, we show that perlecan, a major heparan sulfate proteoglycan of basement membranes, aids in BBB maintenance and repair through pericyte interactions. Using a transient middle cerebral artery occlusion model, we found larger infarct volumes and more BBB leakage in conditional perlecan (Hspg2)-deficient (Hspg2 ^{- / -} -TG) mice than in control mice. Control mice showed increased numbers of pericytes in the ischemic lesion, whereas Hspg2 ^{- / -} -TG mice did not. At the mechanistic level, pericytes attached to recombinant perlecan C-terminal domain V (perlecan DV, endorepellin). Perlecan DV enhanced the PDGF-BB-induced phosphorylation of PDGFRβ, SHP-2, and FAK partially through integrin α5β1 and promoted pericyte migration. Perlecan therefore appears to regulate pericyte recruitment through the cooperative functioning of PDGFRβ and integrin α5β1 to support BBB maintenance and repair following ischemic stroke.

Biological functions of mesenchymal stem cells and clinical implications

Mesenchymal stem cells (MSCs) are isolated from multiple biological tissues-adult bone marrow and adipose tissues and neonatal tissues such as umbilical cord and placenta. In vitro, MSCs show biological features of extensive proliferation ability and multipotency. Moreover, MSCs have trophic, homing/migration and immunosuppression functions that have been demonstrated both in vitro and in vivo. A number of clinical trials are using MSCs for therapeutic interventions in severe degenerative and/or inflammatory diseases, including Crohn's disease and graft-versus-host disease, alone or in combination with other drugs. MSCs are promising for therapeutic applications given the ease in obtaining them, their genetic stability, their poor immunogenicity and their curative properties for tissue repair and immunomodulation. The success of MSC therapy in degenerative and/or inflammatory diseases might depend on the robustness of the biological functions of MSCs, which should be linked to their therapeutic potency. Here, we outline the fundamental and advanced concepts of MSC biological features and underline the biological functions of MSCs in their basic and translational aspects in therapy for degenerative and/or inflammatory diseases.

Epithelial-Mesenchymal Transition Promotes the Differentiation Potential of Xenopus tropicalis Immature Sertoli Cells

Epithelial-mesenchymal transition (EMT) is a fundamental process in embryonic development by which sessile epithelial cells are converted into migratory mesenchymal cells. Our laboratory has been successful in the establishment of Xenopus tropicalis immature Sertoli cells (XtiSCs) with the restricted differentiation potential. The aim of this study is the determination of factors responsible for EMT activation in XtiSCs and stemness window acquisition where cells possess the broadest differentiation potential. For this purpose, we tested three potent EMT inducers—GSK-3 inhibitor (CHIR99021), FGF2, and/or TGF-β1 ligand. XtiSCs underwent full EMT after 3-day treatment with CHIR99021 and partial EMT with FGF2 but not with TGF-β1. The morphological change of CHIR-treated XtiSCs to the typical spindle-like cell shape was associated with the upregulation of mesenchymal markers and the downregulation of epithelial markers. Moreover, only CHIR-treated XtiSCs were able to differentiate into chondrocytes in vitro and cardiomyocytes in vivo. Interestingly, EMT-shifted cells could migrate towards cancer cells (HeLa) in vitro and to the injury site in vivo. The results provide a better understanding of signaling pathways underlying the generation of testis-derived stem cells.

Mesenchymal Stem Cells and Cancer: Clinical Challenges and Opportunities

Stem cell-based therapies exhibit profound therapeutic potential for treating various human diseases, including cancer. Among the cell types that can be used for this purpose, mesenchymal stem cells (MSCs) are considered as promising source of stem cells in personalized cell-based therapies. The inherent tumor-tropic property of MSCs can be used to target cancer cells. Although the impacts of MSCs on tumor progression remain elusive, they have been genetically modified or engineered as targeted anticancer agents which could inhibit tumor growth by blocking different processes of tumor. In addition, there are close interactions between MSCs and cancer stem cells (CSCs). MSCs can regulate the growth of CSCs through paracrine mechanisms. This review aims to focus on the current knowledge about MSCs-based tumor therapies, the opportunities and challenges, as well as the prospective of its further clinical implications.

1,25(OH)2D3 regulates the proangiogenic activity of pericyte through VDR-mediated modulation of VEGF production and signaling of VEGF and PDGF receptors

We have previously demonstrated that the active form of vitamin D (calcitriol; 1,25(OH)₂D₃) is a potent inhibitor of retinal neovascularization. However, the underlying molecular and cellular mechanisms involved remained poorly understood. Perivascular supporting cells including pericytes (PC) play important roles during angiogenesis, vascular maturation, and stabilization of blood vessels. How 1,25(OH)₂D₃ affects retinal PC proliferation and migration, and whether these effects are mediated through vitamin D receptor (VDR), are unknown. Here, we determined the impact of 1,25(OH)₂D₃ on retinal PC prepared from wild‐type (Vdr+/+) and VDR‐deficient (Vdr−/−) mice. Retinal PC expressed significantly higher VDR levels compared to retinal endothelial cells (EC). Unlike retinal EC, 1,25(OH)₂D₃ significantly decreased PC proliferation and migration and resulted in a G₀/G₁ cell cycle arrest. Although 1,25(OH)₂D₃ did not inhibit the proliferation of Vdr−/− PC, it did inhibit their migration. PC adhesion to various extracellular matrix (ECM) proteins and ECM production were also affected by incubation of PC with 1,25(OH)₂D₃. Vdr−/− PC were more adherent compared with Vdr+/+ cells. Mechanistically, incubation of Vdr+/+ PC with 1,25(OH)₂D₃ resulted in an increased expression of vascular endothelial growth factor (VEGF) and attenuation of signaling through VEGF‐R2 and platelet‐derived growth factor receptor‐beta. Incubation with soluble VEGF‐R1 (sFlt‐1) partially reversed the effect of VEGF on Vdr+/+ PC. In addition, incubation of Vdr+/+ PC with VEGF or inhibition of VEGF‐R2 increased VDR expression. Together, these results suggest an important role for retinal PC as a target for vitamin D and VDR action for attenuation of angiogenesis.

Regulator of G-protein signaling 5 regulates the shift from perivascular to parenchymal pericytes in the chronic phase after stroke

Poststroke recovery requires multiple repair mechanisms, including vascular remodeling and blood-brain barrier (BBB) restoration. Brain pericytes are essential for BBB repair and angiogenesis after stroke, but they also give rise to scar-forming platelet-derived growth factor receptor β (PDGFR-β)–expressing cells. However, many of the molecular mechanisms underlying this pericyte response after stroke still remain unknown. Regulator of G-protein signaling 5 (RGS5) has been associated with pericyte detachment from the vascular wall, but whether it regulates pericyte function and vascular stabilization in the chronic phase of stroke is not known. Using RGS5–knockout (KO) mice, we study how loss of RGS5 affects the pericyte response and vascular remodeling in a stroke model at 7 d after ischemia. Loss of RGS5 leads to a shift toward an increase in the number of perivascular pericytes and reduction in the density of parenchymal PDGFR-β–expressing cells associated with normalized PDGFR-β activation after stroke. The redistribution of pericytes resulted in higher pericyte coverage, increased vascular density, preservation of vessel lengths, and a significant reduction in vascular leakage in RGS5-KO mice compared with controls. Our study demonstrates RGS5 in pericytes as an important target to enhance vascular remodeling.—Roth, M., Gaceb, A., Enström, A., Padel, T., Genové, G., Özen, I., Paul, G. Regulator of G-protein signaling 5 regulates the shift from perivascular to parenchymal pericytes in the chronic phase after stroke.

Shedding New Light on The Role of ανβ3 and α5β1 Integrins in Rheumatoid Arthritis

ανβ3 and α5β1 are essential glycoproteins involved in the pathogenesis of rheumatoid arthritis (RA). Understanding of the role these integrins play in disease have been analyzed via description of cells-expressing ανβ3 and α5β1 and their mediators to trigger inflammation. ανβ3 and α5β1 facilitate cells-ECM and cell-cell communication, producing pro-inflammatory factors. Pro-inflammatory factors are essential for the building of undesirable new blood vessels termed angiogenesis which can further lead to destruction of bones and joints. Despite many attempts to target these glycoproteins, there are still some problems, therefore, there is still interest in understanding the synergistic role these integrins play in the pathogenesis of RA. The purpose of this review is to gain insights into the biological effects of ανβ3 and α5β1 in synovial tissues that are relevant to pathogenesis and therapy of RA.

Human Heart Explant-Derived Extracellular Vesicles: Characterization and Effects on the In Vitro Recellularization of Decellularized Heart Valves

Extracellular vesicles (EVs) are particles released from different cell types and represent key components of paracrine secretion. Accumulating evidence supports the beneficial effects of EVs for tissue regeneration. In this study, discarded human heart tissues were used to isolate human heart-derived extracellular vesicles (hH-EVs). We used nanoparticle tracking analysis (NTA) and transmission electron microscopy (TEM) to physically characterize hH-EVs and mass spectrometry (MS) to profile the protein content in these particles. The MS analysis identified a total of 1248 proteins. Gene ontology (GO) enrichment analysis in hH-EVs revealed the proteins involved in processes, such as the regulation of cell death and response to wounding. The potential of hH-EVs to induce proliferation, adhesion, angiogenesis and wound healing was investigated in vitro. Our findings demonstrate that hH-EVs have the potential to induce proliferation and angiogenesis in endothelial cells, improve wound healing and reduce mesenchymal stem-cell adhesion. Last, we showed that hH-EVs were able to significantly promote mesenchymal stem-cell recellularization of decellularized porcine heart valve leaflets. Altogether our data confirmed that hH-EVs modulate cellular processes, shedding light on the potential of these particles for tissue regeneration and for scaffold recellularization.

Far-infrared radiation stimulates platelet-derived growth factor mediated skeletal muscle cell migration through extracellular matrix-integrin signaling

Despite increased evidence of bio-activity following far-infrared (FIR) radiation, susceptibility of cell signaling to FIR radiation-induced homeostasis is poorly understood. To observe the effects of FIR radiation, FIR-radiated materials-coated fabric was put on experimental rats or applied to L6 cells, and microarray analysis, quantitative real-time polymerase chain reaction, and wound healing assays were performed. Microarray analysis revealed that messenger RNA expressions of rat muscle were stimulated by FIR radiation in a dose-dependent manner in amount of 10% and 30% materials-coated. In 30% group, 1,473 differentially expressed genes were identified (fold change [FC] > 1.5), and 218 genes were significantly regulated (FC > 1.5 and p < 0.05). Microarray analysis showed that extracellular matrix (ECM)-receptor interaction, focal adhesion, and cell migration-related pathways were significantly stimulated in rat muscle. ECM and platelet-derived growth factor (PDGF)-mediated cell migration-related genes were increased. And, results showed that the relative gene expression of actin beta was increased. FIR radiation also stimulated actin subunit and actin-related genes. We observed that wound healing was certainly promoted by FIR radiation over 48 h in L6 cells. Therefore, we suggest that FIR radiation can penetrate the body and stimulate PDGF-mediated cell migration through ECM-integrin signaling in rats.

Development of surface functionalization strategies for 3D-printed polystyrene constructs

There is a growing interest in 3D printing to fabricate culture substrates; however, the surface properties of the scaffold remain pertinent to elicit targeted and expected cell responses. Traditional 2D polystyrene (PS) culture systems typically require surface functionalization (oxidation) to facilitate and encourage cell adhesion. Determining the surface properties which enhance protein adhesion from media and cellular extracellular matrix (ECM) production remains the first step to translating 2D PS systems to a 3D culture surface. Here we show that the presence of carbonyl groups to PS surfaces correlated well with successful adhesion of ECM proteins and sustaining ECM production of deposited human mesenchymal stem cells, if the surface has a water contact angle between 50° and 55°. Translation of these findings to custom-fabricated 3D PS scaffolds reveals carbonyl groups continued to enhance spreading and growth in 3D culture. Cumulatively, these data present a method for 3D printing PS and the design considerations required for understanding cell-material interactions. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B:2566-2578, 2019.

A collagen IV-derived peptide disrupts α5β1 integrin and potentiates Ang2/Tie2 signaling

The angiopoietin (Ang)/Tie2 signaling pathway is essential for maintaining vascular homeostasis, and its dysregulation is associated with several diseases. Interactions between Tie2 and α5β1 integrin have emerged as part of this control; however, the mechanism is incompletely understood. AXT107, a collagen IV-derived peptide, has strong antipermeability activity and has enabled the elucidation of this previously undetermined mechanism. Previously, AXT107 was shown to inhibit VEGFR2 and other growth factor signaling via receptor tyrosine kinase association with specific integrins. AXT107 disrupts α5β1 and stimulates the relocation of Tie2 and α5 to cell junctions. In the presence of Ang2 and AXT107, junctional Tie2 is activated, downstream survival signals are upregulated, F-actin is rearranged to strengthen junctions, and, as a result, endothelial junctional permeability is reduced. These data suggest that α5β1 sequesters Tie2 in nonjunctional locations in endothelial cell membranes and that AXT107-induced disruption of α5β1 promotes clustering of Tie2 at junctions and converts Ang2 into a strong agonist, similar to responses observed when Ang1 levels greatly exceed those of Ang2. The potentiation of Tie2 activation by Ang2 even extended to mouse models in which AXT107 induced Tie2 phosphorylation in a model of hypoxia and inhibited vascular leakage in an Ang2-overexpression transgenic model and an LPS-induced inflammation model. Because Ang2 levels are very high in ischemic diseases, such as diabetic macular edema, neovascular age-related macular degeneration, uveitis, and cancer, targeting α5β1 with AXT107 provides a potentially more effective approach to treat these diseases.

Soluble matrix protein is a potent modulator of mesenchymal stem cell performance

We challenge the conventional designation of structural matrix proteins primarily as supporting scaffolds for resident cells. The extracellular matrix protein tropoelastin is classically regarded as a structural component that confers mechanical strength and resilience to tissues subject to repetitive elastic deformation. Here we describe how tropoelastin inherently induces a range of biological responses, even in cells not typically associated with elastic tissues and in a manner unexpected of typical substrate-dependent matrix proteins. We show that tropoelastin alone drives mesenchymal stem cell (MSC) proliferation and phenotypic maintenance, akin to the synergistic effects of potent growth factors such as insulin-like growth factor 1 and basic fibroblast growth factor. In addition, tropoelastin functionally surpasses these growth factors, as well as fibronectin, in allowing substantial media serum reduction without loss of proliferative potential. We further demonstrate that tropoelastin elicits strong mitogenic and cell-attractive responses, both as an immobilized substrate and as a soluble additive, via direct interactions with cell surface integrins αvβ3 and αvβ5. This duality of action converges the long-held mechanistic dichotomy between adhesive matrix proteins and soluble growth factors and uncovers the powerful, untapped potential of tropoelastin for clinical MSC expansion and therapeutic MSC recruitment. We propose that the potent, growth factor-like mitogenic and motogenic abilities of tropoelastin are biologically rooted in the need for rapid stem cell homing and proliferation during early development and/or wound repair.

Fibroblast growth factor improves the motility of human mesenchymal stem cells expanded in a human plasma-derived xeno-free medium through αVβ3 integrin

Human mesenchymal stem cells (MSC) are being explored for cell therapies targeting varied human diseases. For that, cells are being expanded in vitro, many times with fetal bovine serum (FBS) as the main source of growth factors. However, animal-derived components should not be used, to avoid immune rejection from the patient that receives the MSC. To solve this issue, different xeno-free media are being developed, and an industrial-grade human plasma fraction (SCC) is a promising candidate to substitute FBS. Indeed, we have previously shown that MSC expanded in SCC-medium maintain their phenotype and genetic stability. However, a reduction on MSC motility was observed when comparing with MSC motility on FBS-medium. Thus, in this present study, we have tested different factors to improve the motility of MSC in SCC-medium. Time lapse assays and experiments with transwells revealed that supplementation of the xeno-free medium with FGF or PDGF, but not TNF-α or SDF-1, increased MSC motility. Interestingly, FGF and PDGF supplementation also led to alterations on MSC morphology to a shape similar to the one observed when using FBS. The mechanism behind the effect of FGF on MSC motility involved the increased expression of αVβ3 integrin. Furthermore, assays with small molecule inhibitors revealed that the signalling molecule p38 MAPK is important for MSC motility and that MEK/ERK and PI3K/AKT also have a role on FGF-supplemented expanded MSC. Thus, it was found that FGF supplementation can improve the motility of xeno-free-expanded MSC and that the cells motility is regulated by αVβ3 integrin.

Assembly of fibronectin fibrils selectively attenuates platelet-derived growth factor-induced intracellular calcium release in fibroblasts

Cellular responses to platelet-derived growth factor (PDGF) are altered in a variety of pathological conditions, including cancers, fibroses, and vascular diseases, making PDGF-induced signaling pathways important therapeutic targets. The limited success of therapies designed to impact PDGF pathways may be overcome with a clearer understanding of how cells integrate signals from PDGF and the extracellular matrix (ECM). Here, we assessed the effects of fibronectin matrix assembly on the responsiveness of mesenchymal cells to PDGF. Our results indicate that fibroblast-mediated assembly of fibronectin fibrils attenuates intracellular calcium release in response to PDGF. The dose-dependent inhibition of PDGF-induced intracellular calcium release was specific to the ECM form of fibronectin. Further, a recombinant protein engineered to mimic ECM fibronectin similarly attenuated intracellular calcium release in response to PDGF. Of note, fibronectin attenuated the PDGF-calcium signaling axis at the level of phosphoinositide 3-kinase (PI3K) activation. Interestingly, ECM fibronectin did not alter other intracellular signals activated by PDGF, including activation of PDGF receptor β, AKT Ser/Thr kinase, phospholipase Cγ1, and extracellular signal-regulated kinase 1/2 (ERK1/2). Rather, fibronectin inhibited activation of the p55 regulatory subunit of PI3K in response to a variety of stimuli, indicating that ECM fibronectin selectively attenuates the intracellular calcium release cascade while leaving intact other PDGF signaling pathways. Selective regulation of calcium signaling by ECM fibronectin via the p55 regulatory subunit of PI3K represents a mechanism by which cells tune their response to PDGF and may therefore serve as a target to selectively regulate one branch of PDGF signaling.

Fibronectin regulates growth factor signaling and cell differentiation in primary lens cells

Lens epithelial cells are bound to the lens extracellular matrix capsule, of which laminin is a major component. After cataract surgery, surviving lens epithelial cells are exposed to increased levels of fibronectin, and so we addressed whether fibronectin influences lens cell fate, using DCDML cells as a serum-free primary lens epithelial cell culture system. We found that culturing DCDMLs with plasma-derived fibronectin upregulated canonical TGFβ signaling relative to cells plated on laminin. Fibronectin-exposed cultures also showed increased TGFβ signaling-dependent differentiation into the two cell types responsible for posterior capsule opacification after cataract surgery, namely myofibroblasts and lens fiber cells. Increased TGFβ activity could be identified in the conditioned medium recovered from cells grown on fibronectin. Other experiments showed that plating DCDMLs on fibronectin overcomes the need for BMP in fibroblast growth factor (FGF)-induced lens fiber cell differentiation, a requirement that is restored when endogenous TGFβ signaling is inhibited. These results demonstrate how the TGFβ-fibronectin axis can profoundly affect lens cell fate. This axis represents a novel target for prevention of late-onset posterior capsule opacification, a common but currently intractable complication of cataract surgery.

TNBC Challenge: Oligonucleotide Aptamers for New Imaging and Therapy Modalities

Compared to other breast cancers, triple-negative breast cancer (TNBC) usually affects younger patients, is larger in size, of higher grade and is biologically more aggressive. To date, conventional cytotoxic chemotherapy remains the only available treatment for TNBC because it lacks expression of the estrogen receptor (ER), progesterone receptor (PR) and epidermal growth factor receptor 2 (HER2), and no alternative targetable molecules have been identified so far. The high biological and clinical heterogeneity adds a further challenge to TNBC management and requires the identification of new biomarkers to improve detection by imaging, thus allowing the specific treatment of each individual TNBC subtype. The Systematic Evolution of Ligands by EXponential enrichment (SELEX) technique holds great promise to the search for novel targetable biomarkers, and aptamer-based molecular approaches have the potential to overcome obstacles of current imaging and therapy modalities. In this review, we highlight recent advances in oligonucleotide aptamers used as imaging and/or therapeutic agents in TNBC, discussing the potential options to discover, image and hit new actionable targets in TNBC.

Effect of mesenchymal stem cells-derived exosomes on tumor microenvironment: Tumor progression versus tumor suppression

Mesenchymal stem cells (MSCs) are multipotent cells with the potential to differentiate into different cell types. Owing to their immunosuppressive and anti-inflammatory properties, they are widely used in regenerative medicine, but they have a dual effect on cancer progression and exert both growth-stimulatory or -inhibitory effects on different cancer types. It has been proposed that these controversial effects of MSC in tumor microenvironment (TME) are mediated by their polarization to proinflammatory or anti-inflammatory phenotype. In addition, they can polarize the immune system cells that in turn influence tumor progression. One of the mechanisms involved in the TME communications is extracellular vesicles (EVs). MSCs, as one of cell populations in TME, produce a large amount of EVs that can influence tumor development. Similar to MSC, MSC-EVs can exert both anti- or protumorigenic effects. In the current study, we will investigate the current knowledge related to MSC role in cancer progression with a focus on the MSC-EV content in limiting tumor growth, angiogenesis, and metastasis. We suppose MSC-EVs can be used as safe vehicles for delivering antitumor agents to TME.

Overexpression of integrin α7 correlates with advanced disease condition and poor prognosis in rectal cancer patients

The purpose of this study was to investigate the association of integrin α7 expression with clinicopathological features and disease-free survival (DFS) as well as overall survival (OS) in rectal cancer (RC) patients. 219 RC patients who underwent surgery were retrospectively reviewed in this study. Tumor tissues and paired adjacent tissues samples were collected. An immunofluorescence assay was preformed to detect integrin α7 expression. The median follow-up duration in this study was 70 months, and the last follow-up date was 2017/12/31. Integrin α7 was overexpressed in tumor tissues compared to paired adjacent tissues (P<0.001), and its high expression correlated with higher pathological grade (P<0.001), larger tumor size (≥5 cm) (P=0.018), advanced T stage (P=0.003), elevated N stage (P=0.003) and increased TNM stage (P=0.004). Kaplan-Meier curves disclosed that integrin α7 high expression was associated with shorter DFS (P<0.001) and worse OS (P<0.001) compared to low expression. A multivariate Cox's analysis revealed that integrin α7 high expression was an independent factor for unfavorable DFS (P<0.001) and OS (P<0.001) in RC patients. In conclusion, Integrin α7 is highly expressed in tumor tissues and positively correlates with advanced disease condition, and it serves as an independent factor for unfavorable prognosis in RC patients.

PDGF-A suppresses contact inhibition during directional collective cell migration

The leading-edge mesendoderm (LEM) of the Xenopus gastrula moves as an aggregate by collective migration. However, LEM cells on fibronectin in vitro show contact inhibition of locomotion by quickly retracting lamellipodia upon mutual contact. We found that a fibronectin-integrin-syndecan module acts between p21-activated kinase 1 upstream and ephrin B1 downstream to promote the contact-induced collapse of lamellipodia. To function in this module, fibronectin has to be present as puncta on the surface of LEM cells. To overcome contact inhibition in LEM cell aggregates, PDGF-A deposited in the endogenous substratum of LEM migration blocks the fibronectin-integrin-syndecan module at the integrin level. This stabilizes lamellipodia preferentially in the direction of normal LEM movement and supports cell orientation and the directional migration of the coherent LEM cell mass.

Avian lungs: A novel scaffold for lung bioengineering

Allogeneic lung transplant is limited both by the shortage of available donor lungs and by the lack of suitable long-term lung assist devices to bridge patients to lung transplantation. Avian lungs have different structure and mechanics resulting in more efficient gas exchange than mammalian lungs. Decellularized avian lungs, recellularized with human lung cells, could therefore provide a powerful novel gas exchange unit for potential use in pulmonary therapeutics. To initially assess this in both small and large avian lung models, chicken (Gallus gallus domesticus) and emu (Dromaius novaehollandiae) lungs were decellularized using modifications of a detergent-based protocol, previously utilized with mammalian lungs. Light and electron microscopy, vascular and airway resistance, quantitation and gel analyses of residual DNA, and immunohistochemical and mass spectrometric analyses of remaining extracellular matrix (ECM) proteins demonstrated maintenance of lung structure, minimal residual DNA, and retention of major ECM proteins in the decellularized scaffolds. Seeding with human bronchial epithelial cells, human pulmonary vascular endothelial cells, human mesenchymal stromal cells, and human lung fibroblasts demonstrated initial cell attachment on decellularized avian lungs and growth over a 7-day period. These initial studies demonstrate that decellularized avian lungs may be a feasible approach for generating functional lung tissue for clinical therapeutics.

Relevant biological processes for tissue development with stem cells and their mechanistic modeling: A review

A potential alternative for tissue transplants is tissue engineering, in which the interaction of cells and biomaterials can be optimized. Tissue development in vitro depends on the complex interaction of several biological processes such as extracellular matrix synthesis, vascularization and cell proliferation, adhesion, migration, death, and differentiation. The complexity of an individual phenomenon or of the combination of these processes can be studied with phenomenological modeling techniques. This work reviews the main biological phenomena in tissue development and their mathematical modeling, focusing on mesenchymal stem cell growth in three-dimensional scaffolds.

Preconditioning by Hydrogen Peroxide Enhances Multiple Properties of Human Decidua Basalis Mesenchymal Stem/Multipotent Stromal Cells

Stem cell-based therapies rely on stem cell ability to repair in an oxidative stress environment. Preconditioning of mesenchymal stem cells (MSCs) to a stress environment has beneficial effects on their ability to repair injured tissues. We previously reported that MSCs from the decidua basalis (DBMSCs) of human placenta have many important cellular functions that make them potentially useful for cell-based therapies. Here, we studied the effect of DBMSC preconditioning to a stress environment. DBMSCs were exposed to various concentrations of hydrogen peroxide (H₂O₂), and their functions were then assessed. DBMSC expression of immune molecules after preconditioning was also determined. DBMSC preconditioning with H₂O₂ enhanced their proliferation, colonogenicity, adhesion, and migration. In addition, DBMSCs regardless of H₂O₂ treatment displayed antiangiogenic activity. H₂O₂ preconditioning also increased DBMSC expression of genes that promote cellular functions and decreased the expression of genes, which have opposite effect on their functions. Preconditioning also reduced DBMSC expression of IL-1β, but had no effects on the expression of other immune molecules that promote proliferation, adhesion, and migration. These data show that DBMSCs resist a toxic environment, which adds to their potential as a candidate stem cell type for treating various diseases in hostile environments.

Micro/Nano Structural Tantalum Coating for Enhanced Osteogenic Differentiation of Human Bone Marrow Stem Cells

Recently, tantalum has been attracting much attention for its anticorrosion resistance and biocompatibility, and it has been widely used in surface modification for implant applications. To improve its osteogenic differentiation of human bone marrow stem cells (hBMSCs), a micro/nano structure has been fabricated on the tantalum coating surface through the combination of anodic oxidation and plasma spraying method. The morphology, composition, and microstructure of the modified coating were comprehensively studied by employing scanning electron microscopy (SEM), X-ray diffraction (XRD) as well as transmission electron microscopy (TEM). The effects of hierarchical structures as well as micro-porous structure of tantalum coating on the behavior for human bone marrow stem cells (hBMSCs) were evaluated and compared at both cellular and molecular levels in vitro. The experimental results show that a hierarchical micro/nano structure with Ta₂O₅ nanotubes spread onto a micro-scale tantalum coating has been fabricated successfully, which is confirmed to promote cell adhesion and spreading. Besides, the hierarchical micro/nano tantalum coating can provide 1.5~2.1 times improvement in gene expression, compared with the micro-porous tantalum coating. It demonstrates that it can effectively enhance the proliferation and differentiation of hBMSCs in vitro.

Bone marrow derived mesenchymal stem cells transplantation rescues premature ovarian insufficiency induced by chemotherapy

Premature ovarian insufficiency (POI) is an important cause of infertility and also cause menopausal symptoms, which greatly reduced the quality of life for women. Hormone replacement therapy (HRT), as an important strategy, improved the quality of life for patients, however, the role of HRT in promoting fertility remains controversial. Therefore, seeking an optimal regime for POI becomes more urgent. In this study, we established POI model induced by CTX and BUS and utilized bone marrow derived mesenchymal stem cells (BM-MSCs) transplantation to treat the POI. We found that the decrease of estrogen and the increase of FSH induced by administration of CTX and BUS were rescued by BM-MSC transplantation. H&E staining and TUNEL assay showed that there were more healthy ovarian follicles and less apoptosis of ovarian cells after treatment with BM-MSCs. Further studies showed that there was an obvious decrease of Bax, p53, and p21 after transplantation, however, CyclinD2 was increased. In conclusion, our results demonstrated that BM-MSCs could restore injured ovarian function. Inhibiting apoptosis and promoting residual ovarian cell proliferation may contribute to the process.

Oligonucleotide aptamers against tyrosine kinase receptors: Prospect for anticancer applications

Transmembrane receptor tyrosine kinases (RTKs) play crucial roles in cancer cell proliferation, survival, migration and differentiation. Area of intense research is searching for effective anticancer therapies targeting these receptors and, to date, several monoclonal antibodies and small-molecule tyrosine kinase inhibitors have entered the clinic. However, some of these drugs show limited efficacy and give rise to acquired resistance. Emerging highly selective compounds for anticancer therapy are oligonucleotide aptamers that interact with their targets by recognizing a specific three-dimensional structure. Because of their nucleic acid nature, the rational design of advanced strategies to manipulate aptamers for both diagnostic and therapeutic applications is greatly simplified over antibodies. In this manuscript, we will provide a comprehensive overview of oligonucleotide aptamers as next generation strategies to efficiently target RTKs in human cancers.

Extracellular matrix stiffness controls osteogenic differentiation of mesenchymal stem cells mediated by integrin α5

Background

Human mesenchymal stem cell (hMSC) differentiation into osteoblasts has important clinical significance in treating bone injury, and the stiffness of the extracellular matrix (ECM) has been shown to be an important regulatory factor for hMSC differentiation. The aim of this study was to further delineate how matrix stiffness affects intracellular signaling through integrin α5/β1, FAK, and Wnt signaling, subsequently regulating the osteogenic phenotype of hMSCs.

Methods

hMSCs were cultured on tunable polyacrylamide hydrogels coated with fibronectin with stiffness corresponding to a Young’s modulus of 13–16 kPa and 62–68 kPa. After hMSCs were cultured on gels for 1 week, gene expression of alpha-1typeIcollagen, BGLAP, and RUNX2 were evaluated by real-time PCR. After hMSCs were cultured on gels for 24 h, signaling molecules relating to integrin α5 (FAK, ERK, p-ERK, Akt, p-Akt, GSK-3β, p-GSK-3β, and β-catenin) were evaluated by western blot analysis.

Results

Osteogenic differentiation was increased on 62–68 kPa ECM, as evidenced by alpha-1 type I collagen, BGLAP, and RUNX2 gene expression, calcium deposition, and ALP staining. In the process of differentiation, gene and protein expression of integrin α5/β1 increased, together with protein expression of the downstream signaling molecules FAK, p-ERK, p-Akt, GSK-3β, p-GSK-3β, and β-catenin, indicating that these molecules can affect the osteogenic differentiation of hMSCs. An antibody blocking integrin α5 suppressed the stiffness-induced expression of all osteoblast markers examined. In particular, alpha-1 type I collagen, RUNX2, and BGLAP were significantly downregulated, indicating that integrin α5 regulates hMSC osteogenic differentiation. Downstream expression of FAK, ERK, p-ERK, and β-catenin protein was unchanged, whereas Akt, p-Akt, GSK-3β, and p-GSK-3β were upregulated. Moreover, expression of Akt and p-Akt was upregulated with anti-integrin α5 antibody, but no difference was observed for FAK, ERK, and p-ERK between the with or without anti-integrin α5 antibody groups. At the same time, expression of GSK-3β and p-GSK-3β was upregulated and β-catenin levels showed no difference between the groups with or without anti-integrin α5 antibody. Since Akt, p-Akt, GSK-3β, and p-GSK-3β displayed the same changes between the groups with or without anti-integrin α5 antibody, we then detected the links among them. Expression of p-Akt and p-GSK-3β was reduced effectively in the presence of the Akt inhibitor Triciribine. However, Akt, GSK-3β, and β-catenin were unchanged. These results suggested that expression of p-GSK-3β was regulated by p-Akt on 62–68 kPa ECM.

Conclusions

Taken together, our results provide evidence that matrix stiffness (62–68 kPa) affects the osteogenic outcome of hMSCs through mechanotransduction events that are mediated by integrin α5.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-0798-0) contains supplementary material, which is available to authorized users.

Down regulation of ITGA4 and ITGA5 genes after formation of 3D spherules by human Wharton's jelly stem cells (hWJSCs)

Human Wharton's jelly mesenchymal stem cells (hWJSCs) are multipotent stem cells that could be aggregated into 3D spherules. ITGA4 and ITGA5 genes encode α4 and α5 subunits of integrins, respectively. In this study, we analyzed expression levels of ITGA4 and ITGA5 gene mRNAs in undifferentiated and 3D spherules forming hWJSCs in order to determine their expression pattern for possible future treatment of cancer cells in a co-culture fashion. For the purpose of obtaining hWJSCs, umbilical cords were collected from patients with caesarian section at full term delivery. The cells were then characterized according to cell surface markers using flow cytometry. Furthermore pluripotency of the obtained cells was verified. Subsequently the cells were aggregated in 3D spherules using hanging drop cultures. Expression levels of ITGA4 and ITGA5 gene mRNAs were determined by RT-PCR and Real time PCR, both in the initial undifferentiated cells and those aggregated in the spherules. The obtained hWJSCs demonstrated pluripotency, differentiating to adipogenic and osteogenic cells. They also expressed mesenchymal stem cell surface markers. Following the aggregation of these cells and formation of 3D spherules, mRNA expression levels of both genes were significantly reduced (P < 0.05) compared with the initial undifferentiated state. The results of this study demonstrated that aggregation of hWJSCs into spherules alters their expression of ITGA4 and ITGA5. The implications of such an alteration would require further research.

Hybrid-spheroids incorporating ECM like engineered fragmented fibers potentiate stem cell function by improved cell/cell and cell/ECM interactions

Extracellular matrix (ECM) microenvironment is critical for the viability, stemness, and differentiation of stem cells. In this study, we developed hybrid-spheroids of human turbinate mesenchymal stem cells (hTMSCs) by using extracellular matrix (ECM) mimicking fragmented fibers (FFs) for improvement of the viability and functions of hTMSCs. We prepared FFs with average size of 68.26 µm by partial aminolysis of poly L-lactide (PLLA) fibrous sheet (FS), which was coated with polydopamine for improved cell adhesion. The proliferation of hTMSCs within the hybrid-spheroids mixed with fragmented fibers was significantly increased as compared to that from the cell-only group. Cells and fragmented fibers were homogenously distributed with the presence of pore like empty spaces in the structure. LOX-1 staining revealed that the hybrid-spheroids improved the cell viability, which was potentially due to enhanced transport of oxygen through void space generated by engineered ECM. Transmission electron microscopy (TEM) analysis confirmed that cells within the hybrid-spheroid formed strong cell junctions and contacts with fragmented fibers. The expression of cell junction proteins including connexin 43 and E-cadherin was significantly upregulated in hybrid-spheroids by 16.53 ± 0.04 and 28.26 ± 0.11-fold greater than that from cell-only group. Similarly, expression of integrin α_2, α₅, and β₁ was significantly enhanced at the same group by 25.72 ± 0.13, 27.48 ± 0.49, and 592.78 ± 0.06-fold, respectively. In addition, stemness markers including Oct-4, Nanog, and Sox2 were significantly upregulated in hybrid-spheroids by 96.56 ± 0.06, 158.95 ± 0.06, and 115.46 ± 0.47-fold, respectively, relative to the cell-only group. Additionally, hTMSCs within the hybrid-spheroids showed significantly greater osteogenic differentiation under osteogenic media conditions. Taken together, our hybrid-spheroids can be an ideal approach for stem cell expansion and serve as a potential carrier for bone regeneration.

STATEMENT OF SIGNIFICANCE

Cells are spatially arranged within extracellular matrix (ECM) and cell/ECM interactions are crucial for cellular functions. Here, we developed a hybrid-spheroid system incorporating engineered ECM prepared from fragmented electrospun fibers to tune stem cell functions. Conventionally prepared cell spheroids with large diameters (>200 µm) is often prone to hypoxia. In contrast, the hybrid-spheroids significantly enhanced viability and proliferation of human turbinate mesenchymal stem cells (hTMSCs) as compared to spheroid prepared from cell only. Under these conditions, the presence of fragmented fibers also improved maintenance of stemness of hTMSCs for longer time cultured in growth media and demonstrated significantly greater osteogenic differentiation under osteogenic media conditions. Thus, the hybrid-spheroids can be used as a delivery carrier for stem cell based therapy or a 3D culture model for in vitro assay.

The Protein Content of Extracellular Vesicles Derived from Expanded Human Umbilical Cord Blood-Derived CD133+ and Human Bone Marrow-Derived Mesenchymal Stem Cells Partially Explains Why both Sources are Advantageous for Regenerative Medicine

Adult stem cells have beneficial effects when exposed to damaged tissue due, at least in part, to their paracrine activity, which includes soluble factors and extracellular vesicles (EVs). Given the multiplicity of signals carried by these vesicles through the horizontal transfer of functional molecules, human mesenchymal stem cell (hMSCs) and CD133⁺ cell-derived EVs have been tested in various disease models and shown to recover damaged tissues. In this study, we profiled the protein content of EVs derived from expanded human CD133⁺ cells and bone marrow-derived hMSCs with the intention of better understanding the functions performed by these vesicles/cells and delineating the most appropriate use of each EV in future therapeutic procedures. Using LC-MS/MS analysis, we identified 623 proteins for expanded CD133⁺-EVs and 797 proteins for hMSCs-EVs. Although the EVs from both origins were qualitatively similar, when protein abundance was considered, hMSCs-EVs and CD133⁺-EVs were different. Gene Ontology (GO) enrichment analysis in CD133⁺-EVs revealed proteins involved in a variety of angiogenesis-related functions as well proteins related to the cytoskeleton and highly implicated in cell motility and cellular activation. In contrast, when overrepresented proteins in hMSCs-EVs were analyzed, a GO cluster of immune response-related genes involved with immune response-regulating factors acting on phagocytosis and innate immunity was identified. Together our data demonstrate that from the point of view of protein content, expanded CD133⁺-EVs and hMSCs-EVs are in part similar but also sufficiently different to reflect the main beneficial paracrine effects widely reported in pre-clinical studies using expanded CD133⁺ cells and/or hBM-MSCs.

Cancer-associated fibroblasts promote directional cancer cell migration by aligning fibronectin

Cancer-associated fibroblasts (CAFs) are major components of the carcinoma microenvironment that promote tumor progression. However, the mechanisms by which CAFs regulate cancer cell migration are poorly understood. In this study, we show that fibronectin (Fn) assembled by CAFs mediates CAF-cancer cell association and directional migration. Compared with normal fibroblasts, CAFs produce an Fn-rich extracellular matrix with anisotropic fiber orientation, which guides the cancer cells to migrate directionally. CAFs align the Fn matrix by increasing nonmuscle myosin II- and platelet-derived growth factor receptor α-mediated contractility and traction forces, which are transduced to Fn through α5β1 integrin. We further show that prostate cancer cells use αv integrin to migrate efficiently and directionally on CAF-derived matrices. We demonstrate that aligned Fn is a prominent feature of invasion sites in human prostatic and pancreatic carcinoma samples. Collectively, we present a new mechanism by which CAFs organize the Fn matrix and promote directional cancer cell migration.

Biologic Scaffolds

Biologic scaffold materials composed of allogeneic or xenogeneic extracellular matrix are commonly used for the repair and functional reconstruction of injured and missing tissues. These naturally occurring bioscaffolds are manufactured by the removal of the cellular content from source tissues while preserving the structural and functional molecular units of the remaining extracellular matrix (ECM). The mechanisms by which these bioscaffolds facilitate constructive remodeling and favorable clinical outcomes include release or creation of effector molecules that recruit endogenous stem/progenitor cells to the site of scaffold placement and modulation of the innate immune response, specifically the activation of an anti-inflammatory macrophage phenotype. The methods by which ECM biologic scaffolds are prepared, the current understanding of in vivo scaffold remodeling, and the associated clinical outcomes are discussed in this article.

Serum fibronectin distinguishes the early stages of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death, necessitating the discovery of serum markers for its early detection. In this study, a total of 180 serum samples from liver cirrhosis (LC), hepatocellular carcinoma (HCC) patients and paired samples of HCC patients who recovered (Recovery) were analyzed by multiple reaction monitoring-mass spectrometry (MRM-MS) to verify biomarkers. The three-fold crossvalidation was repeated 100 times in the training and test sets to evaluate statistical significance of 124 candidate proteins. This step resulted in 2 proteins that had an area under the receiver operating curve (AUROC) values ≥0.800 in the training (n = 90) and test sets (n = 90). Specifically, fibronectin (FN1, WCGTTQNYDADQK), distinguished HCC from LC patients, with an AUROC value of 0.926 by logistic regression. A FN1 protein was selected for validation in an independent sample (n = 60) using enzyme-linked immunosorbent assay (ELISA). The combination of alpha-fetoprotein (AFP) and FN1 improved the diagnostic performance and differentiated HCC patients with normal AFP levels. Our study has examined candidate markers for the benign disease state and malignancy and has followed up on the consequent recovery. Thus, improvement in the early detection of HCC by a 2-marker panel (AFP + FN1) might benefit HCC patients.

Quantitative proteomic characterization of lung-MSC and bone marrow-MSC using DIA-mass spectrometry

Mesenchymal stromal cells (MSC) are ideal candidates for cell therapies, due to their immune-regulatory and regenerative properties. We have previously reported that lung-derived MSC are tissue-resident cells with lung-specific properties compared to bone marrow-derived MSC. Assessing relevant molecular differences between lung-MSC and bone marrow-MSC is important, given that such differences may impact their behavior and potential therapeutic use. Here, we present an in-depth mass spectrometry (MS) based strategy to investigate the proteomes of lung-MSC and bone marrow-MSC. The MS-strategy relies on label free quantitative data-independent acquisition (DIA) analysis and targeted data analysis using a MSC specific spectral library. We identified several significantly differentially expressed proteins between lung-MSC and bone marrow-MSC within the cell layer (352 proteins) and in the conditioned medium (49 proteins). Bioinformatics analysis revealed differences in regulation of cell proliferation, which was functionally confirmed by decreasing proliferation rate through Cytochrome P450 stimulation. Our study reveals important differences within proteome and matrisome profiles between lung- and bone marrow-derived MSC that may influence their behavior and affect the clinical outcome when used for cell-therapy.

Inhibition of Bone Marrow-Derived Mesenchymal Stem Cells Homing Towards Triple-Negative Breast Cancer Microenvironment Using an Anti-PDGFRβ Aptamer

Bone marrow-derived mesenchymal stem cells (BM-MSCs) are shown to participate in tumor progression by establishing a favorable tumor microenvironment (TME) that promote metastasis through a cytokine networks. However, the mechanism of homing and recruitment of BM-MSCs into tumors and their potential role in malignant tissue progression is poorly understood and controversial. Here we show that BM-MSCs increase aggressiveness of triple-negative breast cancer (TNBC) cell lines evaluated as capability to migrate, invade and acquire stemness markers. Importantly, we demonstrate that the treatment of BM-MSCs with a nuclease-resistant RNA aptamer against platelet-derived growth factor receptor β (PDGFRβ) causes the inhibition of receptor-dependent signaling pathways thus drastically hampering BM-MSC recruitment towards TNBC cell lines and BM-MSCs trans-differentiation into carcinoma-associated fibroblast (CAF)-like cells. Moreover, in vivo molecular imaging analysis demonstrated the aptamer ability to prevent BM-MSCs homing to TNBC xenografts. Collectively, our results indicate the anti-PDGFRβ aptamer as a novel therapeutic tool to interfere with BM-MSCs attraction to TNBC providing the rationale to further explore the aptamer in more complex pre-clinical settings.

Process development of human multipotent stromal cell microcarrier culture using an automated high-throughput microbioreactor

Microbioreactors play a critical role in process development as they reduce reagent requirements and can facilitate high-throughput screening of process parameters and culture conditions. Here, we have demonstrated and explained in detail, for the first time, the amenability of the automated ambr15 cell culture microbioreactor system for the development of scalable adherent human mesenchymal multipotent stromal/stem cell (hMSC) microcarrier culture processes. This was achieved by first improving suspension and mixing of the microcarriers and then improving cell attachment thereby reducing the initial growth lag phase. The latter was achieved by using only 50% of the final working volume of medium for the first 24 h and using an intermittent agitation strategy. These changes resulted in >150% increase in viable cell density after 24 h compared to the original process (no agitation for 24 h and 100% working volume). Using the same methodology as in the ambr15, similar improvements were obtained with larger scale spinner flask studies. Finally, this improved bioprocess methodology based on a serum-based medium was applied to a serum-free process in the ambr15, resulting in >250% increase in yield compared to the serum-based process. At both scales, the agitation used during culture was the minimum required for microcarrier suspension, N_JS . The use of the ambr15, with its improved control compared to the spinner flask, reduced the coefficient of variation on viable cell density in the serum containing medium from 7.65% to 4.08%, and the switch to serum free further reduced these to 1.06-0.54%, respectively. The combination of both serum-free and automated processing improved the reproducibility more than 10-fold compared to the serum-based, manual spinner flask process. The findings of this study demonstrate that the ambr15 microbioreactor is an effective tool for bioprocess development of hMSC microcarrier cultures and that a combination of serum-free medium, control, and automation improves both process yield and consistency. Biotechnol. Bioeng. 2017;114: 2253-2266. © 2017 Wiley Periodicals, Inc.

BNIP3 induction by hypoxia stimulates FASN-dependent free fatty acid production enhancing therapeutic potential of umbilical cord blood-derived human mesenchymal stem cells

Mitophagy under hypoxia is an important factor for maintaining and regulating stem cell functions. We previously demonstrated that fatty acid synthase (FASN) induced by hypoxia is a critical lipid metabolic factor determining the therapeutic efficacy of umbilical cord blood-derived human mesenchymal stem cells (UCB-hMSCs). Therefore, we investigated the mechanism of a major mitophagy regulator controlling lipid metabolism and therapeutic potential of UCB-hMSCs. This study revealed that Bcl2/adenovirus E1B 19 kDa protein-interacting protein 3 (BNIP3)-dependent mitophagy is important for reducing mitochondrial reactive oxygen species accumulation, anti-apoptosis, and migration under hypoxia. And, BNIP3 expression was regulated by CREB binding protein-mediated transcriptional actions of HIF-1α and FOXO3. Silencing of BNIP3 suppressed free fatty acid (FFA) synthesis regulated by SREBP1/FASN pathway, which is involved in UCB-hMSC apoptosis via caspases cleavage and migration via cofilin-1-mediated F-actin reorganization in hypoxia. Moreover, reduced mouse skin wound-healing capacity of UCB-hMSC with hypoxia pretreatment by BNIP3 silencing was recovered by palmitic acid. Collectively, our findings suggest that BNIP3-mediated mitophagy under hypoxia leads to FASN-induced FFA synthesis, which is critical for therapeutic potential of UCB-hMSCs with hypoxia pretreatment.

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BNIP3 induction by hypoxia mainly controls mitophagy and mitochondrial ROS production in UCB-hMSCs.

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BNIP3 silencing impairs UCB-hMSC functions such as survival, migration and free fatty acid production under hypoxia.

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BNIP3 silencing suppresses SREBP1/FASN-mediated free fatty acid production via ROS regulation under hypoxia.

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BNIP3 silencing decreased skin wound healing potential of hypoxia-pretreated UCB-hMSCs.

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Palmitic acid addition recovers decreased therapeutic potential of UCB-hMSCs by BNIP3 silencing.

Involvement of PI3K and MMP1 in PDGF-induced Migration of Human Adipose-derived Stem Cells

Human adult stem cells have widely been examined for their clinical application including their wound healing effect in vivo. To function as therapeutic cells, however, cells must represent the ability of directed migration in response to signals. This study aimed to investigate the mechanism of platelet-derived growth factor (PDGF)-induced migration of the human abdominal adipose-derived stem cells (hADSCs) in vitro. A general matrix metalloproteinase (MMP) inhibitor or a MMP2 inhibitor significantly inhibited the PDGF-induced migration. PDGF treatment exhibited greater mRNA level and denser protein level of MMP1. The conditioned medium of PDGF-treated cells showed a caseinolytic activity of MMP1. Transfection of cells with siRNA against MMP1 significantly inhibited MMP1 expression, its caseinolytic activity, and cell migration following PDGF treatment. Phosphatidylinositol 3-kinase (PI3K) inhibitor reduced the migration by about 50% without affecting ERK and MLC proteins. Rho-associated protein kinase inhibitor mostly abolished the migration and MLC proteins. The results suggest that PDGF might signal hADSCs through PI3K, and MMP1 activity could play an important role in this PDGF-induced migration in vitro.

Human chorionic villous mesenchymal stem/stromal cells modify the effects of oxidative stress on endothelial cell functions

Mesenchymal stem/stromal cells derived from chorionic villi of human term placentae (pMSCs) produce a unique combination of molecules, which modulate important cellular functions of their target cells while concurrently suppressing their immune responses. These properties make MSCs advantageous candidates for cell-based therapy. Our first aim was to examine the effect of high levels of oxidative stress on pMSC functions. pMSCs were exposed to hydrogen peroxide (H₂O₂) and their ability to proliferate and adhere to an endothelial cell monolayer was determined. Oxidatively stressed pMSCs maintained their proliferation and adhesion potentials. The second aim was to measure the ability of pMSCs to prevent oxidative stress-related damage to endothelial cells. Endothelial cells were exposed to H₂O₂, then co-cultured with pMSCs, and the effect on endothelial cell adhesion, proliferation and migration was determined. pMSCs were able to reverse the damaging effects of oxidative stress on the proliferation and migration but not on the adhesion of endothelial cells. These data indicate that pMSCs are not only inherently resistant to oxidative stress, but also protect endothelial cell functions from oxidative stress-associated damage. Therefore, pMSCs could be used as a therapeutic tool in inflammatory diseases by reducing the effects of oxidative stress on endothelial cells.

Dual role of pericyte α6β1-integrin in tumour blood vessels

The α6β1-integrin is a major laminin receptor, and formation of a laminin-rich basement membrane is a key feature in tumour blood vessel stabilisation and pericyte recruitment, processes that are important in the growth and maturation of tumour blood vessels. However, the role of pericyte α6β1-integrin in angiogenesis is largely unknown. We developed mice where the α6-integrin subunit is deleted in pericytes and examined tumour angiogenesis and growth. These mice had: (1) reduced pericyte coverage of tumour blood vessels; (2) reduced tumour blood vessel stability; (3) increased blood vessel diameter; (4) enhanced blood vessel leakiness, and (5) abnormal blood vessel basement membrane architecture. Surprisingly, tumour growth, blood vessel density and metastasis were not altered. Analysis of retinas revealed that deletion of pericyte α6-integrin did not affect physiological angiogenesis. At the molecular level, we provide evidence that pericyte α6-integrin controls PDGFRβ expression and AKT-mTOR signalling. Taken together, we show that pericyte α6β1-integrin regulates tumour blood vessels by both controlling PDGFRβ and basement membrane architecture. These data establish a novel dual role for pericyte α6-integrin as modulating the blood vessel phenotype during pathological angiogenesis.