Cytokine-induced differentiation of multipotent adult progenitor cells into functional smooth muscle cells

CD34+ PI16+ fibroblast progenitors aggravate neointimal lesions of allograft arteries via CCL11/CCR3-PI3K/AKT pathway

Rationale: Transplant-accelerated arteriosclerosis is a common complication that limits the long-term survival of organ transplant recipients. While previous studies have indicated the involvement of CD34+ stem/progenitor cells (SPCs) in this process, their heterogeneity and potential adverse effects remains incompletely understood. Methods: To investigate the role of CD34+ SPCs in transplant arteriosclerosis, we used various genetically modified mouse models, including BALB/c, C57BL/6J, CD34-CreERT2, Rosa26-tdTomato, Rosa26-iDTR, CD34-Dre, PI16-CreERT2, and CAG-LSL-RSR-tdTomato-2A-DTR mice. Single-cell RNA sequencing (scRNA-seq), chemokine antibody microarrays, ELISA assays, and immunohistochemistry were employed to identify fibroblast progenitors and their interactions with smooth muscle cells. Furthermore, in vivo and in vitro experiments targeting the CCL11/CCR3-PI3K/AKT signaling pathway were conducted to assess its role in the pathogenesis of transplant arteriosclerosis. Results: Single-cell RNA-seq and genetic lineage tracing revealed a subpopulation of fibroblast progenitors, characterized by high CD34 and PI16 expression, which differentiated into a distinct chemotactic fibroblast subset. Proteomic and scRNA analysis revealed that this CD34+ PI16- subgroup released CCL11 (Eotaxin-1), which promoted intimal hyperplasia through the paracrine activation of smooth muscle cells. Binding of CCL11 to its receptor CCR3 activated the PI3K/AKT signaling pathway in smooth muscle cells, driving their proliferation and migration. In vivo, overexpression of CCL11 promoted neointimal hyperplasia, while neutralizing CCL11 or inhibiting CCR3 alleviated neointimal formation. Conclusions: These findings identified CD34+ PI16+ fibroblast progenitors that differentiate into specific chemotactic fibroblasts, releasing chemokines pivotal for neointima formation, suggesting a therapeutic strategy targeting their chemotactic activity.

Corpus cavernosum and tunica albuginea reconstruction by tissue engineering: towards functional erectile structures regeneration

BACKGROUND

Current treatments for penile erectile structures reconstruction are limited and remain a great challenge in clinical practice. Tissue engineering techniques using different seed cells and scaffolds to construct a neo-tissue open promising avenues for penile erectile structures repair and replacement and show great promise in the restoration of: structure, mechanical property, and function which matches the original tissue.

METHODS

A comprehensive literature review was conducted by accessing the NCBI PubMed, Cochrane, and Google Scholar databases from January 1, 1990, to January, 1, 2022 using the search terms "Tissue engineering, Corpus cavernosum (CC), Tunica albuginea (TA), Acellular Matrix, Penile Reconstruction". Articles were screened and assessed by two independent reviewers to determine whether those met the inclusion criteria, and a total of 19 articles were being selected and included in the data analysis.

RESULTS

Tissue engineered cell-seeded scaffold can reconstruct a similar structure to native TA and CC and showed good histocompatibility with no immunological rejection. The results of the evaluation of morphological feature, intracavernosal pressure, and erectile-related nitric oxide (NO) expression were strongly proofs that the tissue engineered graft can significantly improve the penile erectile and ejaculatory function. In addition, increasing the purity of seed cells, improving the mechanical properties of the scaffold, providing appropriate induction for stem cells, and optimizing cell delivery systems are potential approaches to improve reconstructive outcomes. Currently, a larger animal model, comparable in size to the human penis, is needed to test the feasibility of the engineered grafts.

CONCLUSION

Our review summarized the research in tissue engineering of CC and TA. It showed great promise in reconstructing the functional structures and restoring the erection and ejaculatory function. With continuous advancement in the field, tissue-engineered penile erectile structures hold substantial potential to enhance clinical outcomes for patients.

Endothelial Cells Increase Mesenchymal Stem Cell Differentiation in Scaffold-Free 3D Vascular Tissue

In this study, we present a versatile, scaffold-free approach to create ring-shaped engineered vascular tissue segments using human mesenchymal stem cell-derived smooth muscle cells (hMSC-SMCs) and endothelial cells (ECs). We hypothesized that incorporation of ECs would increase hMSC-SMC differentiation without compromising tissue ring strength or fusion to form tissue tubes. Undifferentiated hMSCs and ECs were co-seeded into custom ring-shaped agarose wells using four different concentrations of ECs: 0%, 10%, 20%, and 30%. Co-seeded EC and hMSC rings were cultured in SMC differentiation medium for a total of 22 days. Tissue rings were then harvested for histology, Western blotting, wire myography, and uniaxial tensile testing to examine their structural and functional properties. Differentiated hMSC tissue rings comprising 20% and 30% ECs exhibited significantly greater SMC contractile protein expression, endothelin-1 (ET-1)-meditated contraction, and force at failure compared with the 0% EC rings. On average, the 0%, 10%, 20%, and 30% EC rings exhibited a contractile force of 0.745 ± 0.117, 0.830 ± 0.358, 1.31 ± 0.353, and 1.67 ± 0.351 mN (mean ± standard deviation [SD]) in response to ET-1, respectively. Additionally, the mean maximum force at failure for the 0%, 10%, 20%, and 30% EC rings was 88.5 ± 36. , 121 ± 59.1, 147 ± 43.1, and 206 ±  0.8 mN (mean ± SD), respectively. Based on these results, 30% EC rings were fused together to form tissue-engineered blood vessels (TEBVs) and compared with 0% EC TEBV controls. The addition of 30% ECs in TEBVs did not affect ring fusion but did result in significantly greater SMC protein expression (calponin and smoothelin). In summary, co-seeding hMSCs with ECs to form tissue rings resulted in greater contraction, strength, and hMSC-SMC differentiation compared with hMSCs alone and indicates a method to create a functional 3D human vascular cell coculture model.

The Role of Progenitor Cells in the Pathogenesis of Arteriosclerosis

The increasing incidence of arteriosclerosis has become a significant global health burden. Arteriosclerosis is characterized by the thickening and hardening of arterial walls, which can lead to the narrowing or complete blockage of blood vessels. However, the pathogenesis of the disease remains incompletely understood. Recent research has shown that stem and progenitor cells found in the bone marrow and local vessel walls play a role in the development of arteriosclerosis by differentiating into various types of vascular cells, including endothelial cells, smooth muscle cells, fibroblasts, and inflammatory cells. This review aims to provide a comprehensive understanding of the role of stem and progenitor cells in the pathogenesis of arteriosclerosis, shedding light on the underlying mechanisms and potential therapeutic approaches for this disease.

A Review of the Evidence for Tryptophan and the Kynurenine Pathway as a Regulator of Stem Cell Niches in Health and Disease

Stem cells are ubiquitously found in various tissues and organs in the body, and underpin the body's ability to repair itself following injury or disease initiation, though repair can sometimes be compromised. Understanding how stem cells are produced, and functional signaling systems between different niches is critical to understanding the potential use of stem cells in regenerative medicine. In this context, this review considers kynurenine pathway (KP) metabolism in multipotent adult progenitor cells, embryonic, haematopoietic, neural, cancer, cardiac and induced pluripotent stem cells, endothelial progenitor cells, and mesenchymal stromal cells. The KP is the major enzymatic pathway for sequentially catabolising the essential amino acid tryptophan (TRP), resulting in key metabolites including kynurenine, kynurenic acid, and quinolinic acid (QUIN). QUIN metabolism transitions into the adjoining de novo pathway for nicotinamide adenine dinucleotide (NAD) production, a critical cofactor in many fundamental cellular biochemical pathways. How stem cells uptake and utilise TRP varies between different species and stem cell types, because of their expression of transporters and responses to inflammatory cytokines. Several KP metabolites are physiologically active, with either beneficial or detrimental outcomes, and evidence of this is presented relating to several stem cell types, which is important as they may exert a significant impact on surrounding differentiated cells, particularly if they metabolise or secrete metabolites differently. Interferon-gamma (IFN-γ) in mesenchymal stromal cells, for instance, highly upregulates rate-limiting enzyme indoleamine-2,3-dioxygenase (IDO-1), initiating TRP depletion and production of metabolites including kynurenine/kynurenic acid, known agonists of the Aryl hydrocarbon receptor (AhR) transcription factor. AhR transcriptionally regulates an immunosuppressive phenotype, making them attractive for regenerative therapy. We also draw attention to important gaps in knowledge for future studies, which will underpin future application for stem cell-based cellular therapies or optimising drugs which can modulate the KP in innate stem cell populations, for disease treatment.

Osteogenic Differentiation Potential of Mesenchymal Stem Cells Using Single Cell Multiomic Analysis

Mesenchymal stem cells (MSC) are multipotent stem cells that can differentiate into multiple cell types, including osteoblasts, chondrocytes, and adipocytes. Osteoblast differentiation is reduced during osteoporosis development, resulting in reduced bone formation. Further, MSC isolated from different donors possess distinct osteogenic capacity. In this study, we used single-cell multiomic analysis to profile the transcriptome and epigenome of MSC from four healthy donors. Data were obtained from ~1300 to 1600 cells for each donor. These cells were clustered into four groups, indicating that MSC from different donors have distinct chromatin accessible regulatory elements for regulating gene expression. To investigate the mechanism by which MSC undergo osteogenic differentiation, we used the chromatin accessibility data from the single-cell multiome data to identify individual-specific enhancer-promoter pairs and evaluated the expression levels and activities of the transcriptional regulators. The MSC from four donors showed distinct differentiation potential into osteoblasts. MSC of donor 1 showed the largest average motif activities, indicating that MSC from donor 1 was most likely to differentiate into osteoblasts. The results of our validation experiments were consistent with the bioinformatics prediction. We also tested the enrichment of genome-wide association study (GWAS) signals of several musculoskeletal disease traits in the patient-specific chromatin accessible regions identified in the single-cell multiome data, including osteoporosis, osteopenia, and osteoarthritis. We found that osteoarthritis-associated variants were only enriched in the regions identified from donor 4. In contrast, osteoporosis and osteopenia variants were enriched in regions from donor 1 and least enriched in donor 4. Since osteoporosis and osteopenia are related to the density of bone cells, the enrichment of variants from these traits should be correlated with the osteogenic potential of MSC. In summary, this study provides large-scale data to link regulatory elements with their target genes to study the regulatory relationships during the differentiation of mesenchymal stem cells and provide a deeper insight into the gene regulatory mechanism.

A novel co-culture assay to evaluate the effects of sympathetic innervation on vascular smooth muscle differentiation

Dedifferentiation of vascular smooth muscle cells (VSMCs) from a functional phenotype to an inverse synthetic phenotype is a symptom of cardiovascular disorders, such as atherosclerosis and hypertension. The sympathetic nervous system (SNS) is an essential regulator of the differentiation of vascular smooth muscle cells (VSMCs). In addition, numerous studies suggest that SNS also stimulates VSMCs to retain their contractile phenotype. However, the molecular mechanisms for this stimulation have not been thoroughly studied. In this study, we used a novel in vitro co-culture method to evaluate the effective cellular interactions and stimulatory effects of sympathetic neurons on the differentiation of VSMCs. We co-cultured rat neural-like pheochromocytoma cells (PC12) and rat aortic VSMCs with this method. Expression of VSMCs contractile genes, including smooth muscle actin (acta2), myosin heavy chain (myh11), elastin (eln), and smoothelin (smtn), were determined by quantitative real-time-PCR analysis as an indicator of VSMCs differentiation. Fold changes for specific contractile genes in VSMCs grown in vitro for seven days in the presence (innervated) and absence (non-innervated) of sympathetic neurons were 3.5 for acta2, 6.5 for myh11, 4.19 for eln, and 4 for smtn (normalized to Tata Binding Protein (TBP)). As a result, these data suggest that sympathetic innervation promotes VSMCs' contractile gene expression and also maintains VSMCs' functional phenotype.

Differentiation and Engineering of Human Stem Cells for Smooth Muscle Generation

Cardiovascular diseases are responsible for 31% of global deaths and are considered the main cause of death and disability worldwide. Stem cells from various sources have become attractive options for a range of cell-based therapies for smooth muscle tissue regeneration. However, for efficient myogenic differentiation, the stem cell characteristics, cell culture conditions, and their respective microenvironments need to be carefully assessed. This review covers the various approaches involved in the regeneration of vascular smooth muscles by conditioning human stem cells. This article delves into the different sources of stem cells used in the generation of myogenic tissues, the role of soluble growth factors, use of scaffolding techniques, biomolecular cues, relevance of mechanical stimulation, and key transcription factors involved, aimed at inducing myogenic differentiation. Impact statement The review article's main goal is to discuss the recent advances in the field of smooth muscle tissue regeneration. We look at various cell sources, growth factors, scaffolds, mechanical stimuli, and factors involved in smooth muscle formation. These stem cell-based approaches for vascular muscle formation will provide various options for cell-based therapies with long-term beneficial effects on patients.

CRISPR activation of endogenous genes reprograms fibroblasts into cardiovascular progenitor cells for myocardial infarction therapy

Fibroblasts can be reprogrammed into cardiovascular progenitor cells (CPCs) using transgenic approaches, although the underlying mechanism remains unclear. We determined whether activation of endogenous genes such as Gata4, Nkx2.5, and Tbx5 can rapidly establish autoregulatory loops and initiate CPC generation in adult extracardiac fibroblasts using a CRISPR activation system. The induced fibroblasts (>80%) showed phenotypic changes as indicated by an Nkx2.5 cardiac enhancer reporter. The progenitor characteristics were confirmed by colony formation and expression of cardiovascular genes. Cardiac sphere induction segregated the early and late reprogrammed cells that can generate functional cardiomyocytes and vascular cells in vitro. Therefore, they were termed CRISPR-induced CPCs (ciCPCs). Transcriptomic analysis showed that cell cycle and heart development pathways were important to accelerate CPC formation during the early reprogramming stage. The CRISPR system opened the silenced chromatin locus, thereby allowing transcriptional factors to access their own promoters and eventually forming a positive feedback loop. The regenerative potential of ciCPCs was assessed after implantation in mouse myocardial infarction models. The engrafted ciCPCs differentiated into cardiovascular cells in vivo but also significantly improved contractile function and scar formation. In conclusion, multiplex gene activation was sufficient to drive CPC reprogramming, providing a new cell source for regenerative therapeutics.

Generation and Characterization of Human Mesenchymal Stem Cell-Derived Smooth Muscle Cells

Cardiovascular diseases are the leading cause of death worldwide. A completely autologous treatment can be achieved by using elastogenic mesenchymal stem cell (MSC)-derived smooth muscle cells (SMC) at the affected tissue site of vascular diseases such as abdominal aortic aneurysms (AAA). Thus, our work focused on evaluating the efficacy of (a) the combination of various growth factors, (b) different time periods and (c) different MSC lines to determine the treatment combination that generated SMCs that exhibited the greatest elastogenicity among the tested groups using Western blotting and flow cytometry. Additionally, total RNA sequencing was used to confirm that post-differentiation cells were upregulating SMC-specific gene markers. Results indicated that MSCs cultured for four days in PDGF + TGFβ1 (PT)-infused differentiation medium showed significant increases in SMC markers and decreases in MSC markers compared to MSCs cultured without differentiation factors. RNA Seq analysis confirmed the presence of vascular smooth muscle formation in MSCs differentiated in PT medium over a seven-day period. Overall, our results indicated that origin, growth factor treatment and culture period played a major role in influencing MSC differentiation to SMCs.

Tissue engineering to treat pelvic organ prolapse

Pelvic organ prolapse (POP) is a frequent chronic illness, which seriously affects women's living quality. In recent years, tissue engineering has made superior progress in POP treatment, and biological scaffolds have received considerable attention. Nevertheless, pelvic floor reconstruction still faces severe challenges, including the construction of ideal scaffolds, the selection of optimal seed cells, and growth factors. This paper summarizes the recent progress of pelvic floor reconstruction in tissue engineering, and discusses the problems that need to be further considered and solved to provide references for the further development of this field.

Novel low shear 3D bioreactor for high purity mesenchymal stem cell production

Bone marrow derived human Mesenchymal Stem Cells (hMSCs) are an attractive candidate for regenerative medicine. However, their harvest can be invasive, painful, and expensive, making it difficult to supply the enormous amount of pure hMSCs needed for future allogeneic therapies. Because of this, a robust method of scaled bioreactor culture must be designed to supply the need for high purity, high density hMSC yields. Here we test a scaled down model of a novel bioreactor consisting of an unsubmerged 3D printed Polylactic Acid (PLA) lattice matrix wetted by culture media. The growth matrix is uniform, replicable, and biocompatible, enabling homogenous cell culture in three dimensions. The goal of this study was to prove that hMSCs would culture well in this novel bioreactor design. The system tested resulted in comparable stem cell yields to other cell culture systems using bone marrow derived hMSCs, while maintaining viability (96.54% ±2.82), high purity (>98% expression of combined positive markers), and differentiation potential.

Immunomodulatory and antimicrobial non-mulberry Antheraea mylitta silk fibroin accelerates in vitro fibroblast repair and regeneration by protecting oxidative stress

The antimicrobial nature of Antharaea mylitta silk-fibroin (SF) is reported but antioxidant potential and the immunomodulatory role towards the fibroblast cell repair process is not explored. Polyurethane is reported to have inflammatory potential by mononuclear cells directed cytokine release, which can guide fibroblast repair. Present study demonstrates the conjunctive effect of inflammatory PU/SF to regulate the favorable shift from pro-inflammatory to anti-inflammatory cytokine stimulation for accelerated fibroblast repair. Minimal inhibitory concentration of SF was determined against pathogenic strains and the effect of SF was investigated for fibroblast NIH3T3 cell adhesion. SF doses (8, 8.5, 9 mg mL⁻¹) were found to be greater than both the IC₅₀ of DPPH scavenging and the ED₅₀ for NIH3T3 proliferation. Anti-lipid peroxidase (ALP) activity of SF doses and citric acid-treated NIH3T3 cells were compared under hydrogen peroxide (H₂O₂) induced oxidative stress. 9 mg mL⁻¹ SF showed greater ALP activity than the citric acid standard. SF-driven protection to oxidative damage was measured by viable cell fraction in trypan blue dye exclusion assay where 9 mg mL⁻¹ SF showed the highest viability (p ≤ 0.05). 9 mg mL⁻¹ SF was blended with PU for scaffold (w/v = 2 : 5, 2 : 7, 2 : 9) fabrication. The protective effect of PU/SF (2 : 5, 2 : 7, 2 : 9) against oxidative stress was verified by damaged cell survival in MTT assay and DNA quantification. The highest number of cells survived on PU/SF (2 : 9) at all intervals (p ≤ 0.01) upon oxidative damage; PU/SF (2 : 9) was also fabricated by employing the immobilization technique. Immobilized PU/SF (2 : 9) exhibited a greater zone of microbial inhibition, a higher extent of inhibition to microbial adherence, and caused more LDH release from bacterial cell membrane due to membrane rupture, resulting in bacterial cell death (E. coli, K. pneumoniae, P. aeruginosa, S. aureus) compared to the experimental results shown by blended PU/SF (2 : 9). The protective nature of PU/SF (2 : 9) against oxidative stress was ensured through the LDH activity of damaged NIH3T3 cells. Initial raised IL-6, TNF-alpha (pro-inflammatory cytokines) and lowered IL-8, IL-10 (anti-inflammatory cytokine) profiles coupled with fallen IL-6, TNF-alpha, and elevated IL-8, IL-10 at later hours synergistically progress the inflammatory phase of in vitro scratch wound repair in mononuclear culture treated by PU/SF (2 : 9).

Initially SF accelerated pro-inflammatory cytokines, restricted anti-inflammatory cytokines; later it regulated in reverse order. SF potentially eradicated ROS and promoted Ki-67 cellular regeneration whereas pristine PU could not.

Mesenchymal Stem Cell-Mediated Therapy of Peripheral Artery Disease Is Stimulated by a Lamin A-Progerin Binding Inhibitor

Objective

Human adipose tissue-derived mesenchymal stem cells (ASCs) have been reported to promote angiogenesis and tissue repair. However, poor survival and engraftment efficiency of transplanted ASCs are the major bottlenecks for therapeutic application. The present study aims to improve the therapeutic efficacy of ASCs for peripheral artery diseases.

Methods

Hydrogen peroxide (H₂O₂) was used to induce apoptotic cell death in ASCs. To measure apoptosis, we used flow cytometry-based apoptosis analysis and terminal deoxynucleotidyl transferase dUTP nick end labeling staining. A murine hindlimb ischemia model was established to measure the ASC-mediated therapeutic angiogenesis and in vivo survival ability of ASCs.

Results

We identified that the inhibitor of lamin A-progerin binding, JH4, protects ASCs against H₂O₂-induced oxidative stress and apoptosis. Co-administration of ASCs with JH4 improved ASC-mediated blood reperfusion recovery and limb salvage compared to that of the control group in a mouse hind limb ischemia model. Immunofluorescence showed that JH4 treatment potentiated ASC-mediated vascular regeneration via reducing ASC apoptosis post transplantation.

Conclusion

JH4 exerts anti-apoptotic effects in ASCs in conditions of oxidative stress, and contributes to the repair of ischemic hind limb injury by improving cell survival.

Plasminogen regulates mesenchymal stem cell-mediated tissue repair after ischemia through Cyr61 activation

Stem cell transplantation has emerged as a promising strategy in regenerative medicine. However, the poor survival and persistence of the transplanted cells, including mesenchymal stem cells (MSCs), in the hostile ischemic microenvironments represents a major therapeutic barrier. Here we report that plasminogen (Plg) stimulated MSC functions and promoted MSC survival during tissue repair after ischemia. Genetic Plg ablation abolished MSC survival, migration, and proliferation in mouse ischemic limbs, and abrogated MSC-mediated blood reperfusion, neovascularization, and tissue repair after ischemia, suggesting a critical role for Plg in MSC-mediated tissue repair. Furthermore, multiplex cytokine array analysis identified that Plg cleaved and activated cysteine-rich protein 61 (Cyr61), an ECM-associated growth factor, to stimulate MSC survival and migration. Overexpression with truncated Cyr61 in MSCs rescued blood reperfusion after hind limb ischemia in Plg-deficient mice. Finally, Plg-mediated Cyr61 cleavage promoted endothelial cell migration and neovascularization in vitro and in vivo. Our study reveals that Plg promotes MSC survival, persistence, and paracrine effects and improves postischemic neovascularization and tissue repair through Cyr61 cleavage and activation. Thus, targeting Plg/Cyr61 may offer exciting therapeutic opportunities for strengthening MSC therapy in ischemic diseases.

Plasminogen promotes mesenchymal stem cell function and improves post-ischemic neovascularization and tissue repair through cysteine-rich protein 61 activation.

TRIM28 and TRIM27 are required for expressions of PDGFRβ and contractile phenotypic genes by vascular smooth muscle cells

Vascular smooth muscle cells (VSMCs) in the normal arterial media continually express contractile phenotypic markers which are reduced dramatically in response to injury. Tripartite motif-containing proteins are a family of scaffold proteins shown to regulate gene silencing, cell growth, and differentiation. We here investigated the biological role of tripartite motif-containing 28 (TRIM28) and tripartite motif-containing 27 (TRIM27) in VSMCs. We observed that siRNA-mediated knockdown of TRIM28 and TRIM27 inhibited platelet-derived growth factor (PDGF)-induced migration in human VSMCs. Both TRIM28 and TRIM27 can regulate serum response element activity and were required for maintaining the contractile gene expression in human VSMCs. At the same time, TRIM28 and TRIM27 knockdown reduced the expression of PDGF receptor-β (PDGFRβ) and the phosphorylation of its downstream signaling components. Immunoprecipitation showed that TRIM28 formed complexes with TRIM27 through its N-terminal RING-B boxes-Coiled-Coil domain. Furthermore, TRIM28 and TRIM27 were shown to be upregulated and mediate the VSMC contractile marker gene and PDGFRβ expression in differentiating human bone marrow mesenchymal stem cells. In conclusion, we identified that TRIM28 and TRIM27 cooperatively maintain the endogenous expression of PDGFRβ and contractile phenotype of human VSMCs.

Mesenchymal stem cells and the embryonic reawakening theory of BPH

The prostate is the only organ in a man that continues to grow with age. John McNeal proposed, 40 years ago, that this BPH is characterized by an age-related reinitiation of benign neoplastic growth selectively in developmentally abortive distal ducts within the prostate transition-periurethral zone (TPZ), owing to a reawakening of inductive stroma selectively within these zones. An innovative variant of this hypothesis is that, owing to its location, the TPZ is continuously exposed to urinary components and/or autoantigens, which produces an inflammatory TPZ microenvironment that promotes recruitment of bone marrow-derived mesenchymal stem cells (MSCs) and generates a paracrine-inductive stroma that reinitiates benign neoplastic nodular growth. In support of this hypothesis, MSCs infiltrate human BPH tissue and have the ability to stimulate epithelial stem cell growth. These results provide a framework for defining both the aetiology of BPH in ageing men and insights into new therapeutic approaches.

Endocardial Cell Plasticity in Cardiac Development, Diseases and Regeneration

Endocardial cells are specialized endothelial cells that form the innermost layer of the heart wall. By virtue of genetic lineage-tracing technology, many of the unexpected roles of endocardium during murine heart development, diseases, and regeneration have been identified recently. In addition to heart valves developed from the well-known endothelial to mesenchymal transition, recent fate-mapping studies using mouse models reveal that multiple cardiac cell lineages are also originated from the endocardium. This review focuses on a variety of different cell types that are recently reported to be endocardium derived during murine heart development, diseases, and regeneration. These multiple cell fates underpin the unprecedented roles of endocardial progenitors in function, pathological progression, and regeneration of the heart. Because emerging studies suggest that developmental mechanisms can be redeployed and recapitulated in promoting heart disease development and also cardiac repair and regeneration, understanding the mechanistic regulation of endocardial plasticity and modulation of their cell fate conversion may uncover new therapeutic potential in facilitating heart regeneration.

In vitro heterogeneity of porcine adipose tissue-derived stem cells

Tissue-specific adult stem cells (ASC) are heterogeneous and characterized by a mix of progenitor cells that produce cells at various stages of differentiation, and ultimately different terminally differentiated cells. Understanding the heterogeneity of ASCs may lead to the development of improved protocols of cell isolation and optimized cell therapy clinical protocols. Using a combination of enzymatic and explant culture protocols, we obtained pADSC population, which is composed by two distinct morphologies: fibroblast-like cells (FLCs) and endothelial-like cells (ELCs). Both cell sub-types efficiently formed colonies, expressed CD90⁺/CD105⁺/CD44⁺, and differentially expressed such markers such as Nestin, Vimentin, Fibronectin, Cytokeratin, Connexin 43, CD31, CD34 and CD146 as well as the pluripotent stem cell markers Oct-4, Nanog and Sox2. Mixed populations of pADSCs did not lose their multipotentiality and the cells were able to undergo osteogenic, chondrogenic, adipogenic and myogenic differentiation. Furthermore, the mixed population spontaneously formed capillary tube structures. Our findings suggest that different subpopulations can be isolated from adipose tissue and that the ADSCs need to be better evaluated using a wide panel of different markers related to cell differentiation, which is important for stem cell therapy and regenerative medicine, particularly for advanced stem cells therapies - products that are currently under investigation or even use.

Differentiation potential of different regions-derived same donor human Wharton's jelly mesenchymal stem cells into functional smooth muscle-like cells

The present study evaluates the transdifferentiation potential of different region-derived same donor Wharton's jelly MSCs (WJMSCs) into functional smooth muscle-like cells (SMLCs). All regions showed baseline expression for early smooth muscle cell (SMC) markers (αSMA and SM22-α) whereas mid marker CALPONIN gradually reduced during in vitro culture expansion and late marker myosin heavy chain type-11 (MHY-11) was completely absent. Furthermore, WJMSCs were induced to SMLCs using DMEM containing 10% FBS supplemented with different concentrations/combinations of TGF-β1 and PDGF-BB under normoxia (20% O₂) condition. Three treatment groups namely group A: 2.5 ng/ml TGF-β1, group B: 5 ng/ml PDGF-BB and group C: 2.5 ng/ml TGF-β1 + 5 ng/ml PDGF-BB were used for the induction of WJMSCs into SMLCs. Cells were evaluated for SMC-specific marker expression at different time intervals. Finally, selection of the SMC-specific highly potent region along with the most suitable treatment group was done on the basis of highest outcome in terms of SMC-specific marker expression and functional competence of transdifferentiated cells. Among all regions, baby region-derived WJMSCs (B-WJMSCs) exhibited highest SMC marker expression and functional ability. To mimic the in vivo physiological conditions, hypoxic conditions (3% O₂) were used to evaluate the effect of low oxygen on the SMLC differentiation potential of selected WJMSCs using previously used same parameters. Annexin-V assay was performed to check the effect of cytokines and different oxygen concentrations, which revealed no significant differences. It was concluded that different induction conditions have different but positive effects on the functional SMLC differentiation ability of WJMSCs.

Induction of human umbilical cord mesenchymal stem cells into tissue-forming cells in a murine model: implications for pelvic floor reconstruction

HUMSCs were isolated, differentiated and characterized in vitro. Both HUMSCs and smooth muscle cells differentiated from HUMSCs were used to fabricate tissue-engineered fascia equivalents. Forty-eight mature female Sprague Dawley rats were randomly assigned to four groups: group A (GynemeshTMPS, n = 12), group B (GynemeshTMPS + HUMSCs; n = 12), group C (GynemeshTMPS + smooth muscle cells differentiated from HUMSCs; n = 12) and group D (GynemeshTMPS + HUMSCs + smooth muscle cells differentiated from HUMSCs; n = 12). The posterior vaginal wall was incised from the introitus and the mesh was then implanted. Three implants of each type were tested at 1, 4, 8 and 12 weeks. Fibrotic remodeling, inflammation, vascularization and tissue regeneration were histologically assessed. The levels of type I and type III collagen were determined. There was no difference in fibrotic remodeling between cell-seeded and unseeded meshes at any time (p > 0.05). At 12 weeks, there did not appear to be fewer inflammatory cells around the filament bundles in the mesh with cells compared with the mesh alone (P > 0.05). Group D showed a trend toward better vascularization at 12 weeks compared with group A (P < 0.05). Twelve weeks after implantation, a thin layer of new tissue growth covered the unseeded scaffold and a thicker layer covered the cell-seeded scaffold (P < 0.05). No significant difference in the ratio of collagen type I/III could be detected among the different groups after 12 weeks (P > 0.05). HUMSCs with differentiated smooth muscle cells might have a potential role in fascia tissue engineering to repair POP in the future.

Characterization and transplantation of enteric neural crest cells from human induced pluripotent stem cells

The enteric nervous system (ENS) is recognized as a second brain because of its complexity and its largely autonomic control of bowel function. Recent progress in studying the interactions between the ENS and the central nervous system (CNS) has implicated alterations of the gut/brain axis as a possible mechanism in the pathophysiology of autism spectrum disorders (ASDs), Parkinson's disease (PD) and other human CNS disorders, whereas the underlying mechanisms are largely unknown because of the lack of good model systems. Human induced pluripotent stem cells (hiPSCs) have the ability to proliferate indefinitely and differentiate into cells of all three germ layers, thus making iPSCs an ideal source of cells for disease modelling and cell therapy. Here, hiPSCs were induced to differentiate into neural crest stem cells (NCSCs) efficiently. When co-cultured with smooth muscle layers of ganglionic gut tissue, the NCSCs differentiated into different subtypes of mature enteric-like neurons expressing nitric oxide synthase (nNOS), vasoactive intestinal polypeptide (VIP), choline acetyltransferase (ChAT) or calretinin with typical electrophysiological characteristics of functional neurons. Furthermore, when they were transplanted into aneural or aganglionic chick, mouse or human gut tissues in ovo, in vitro or in vivo, hiPSC-derived NCSCs showed extensive migration and neural differentiation capacity, generating neurons and glial cells that expressed phenotypic markers characteristic of the enteric nervous system. Our results indicate that enteric NCSCs derived from hiPSCs supply a powerful tool for studying the pathogenesis of gastrointestinal disorders and brain/gut dysfunction and represent a potentially ideal cell source for enteric neural transplantation treatments.

Vascular precursor cells in tissue injury repair

Vascular precursor cells include stem cells and progenitor cells giving rise to all mature cell types in the wall of blood vessels. When tissue injury occurs, local hypoxia and inflammation result in the generation of vasculogenic mediators which orchestrate migration of vascular precursor cells from their niche environment to the site of tissue injury. The intricate crosstalk among signaling pathways coordinates vascular precursor cell proliferation and differentiation during neovascularization. Establishment of normal blood perfusion plays an essential role in the effective repair of the injured tissue. In recent years, studies on molecular mechanisms underlying the regulation of vascular precursor cell function have achieved substantial progress, which promotes exploration of vascular precursor cell-based approaches to treat chronic wounds and ischemic diseases in vital organ systems. Verification of safety and establishment of specific guidelines for the clinical application of vascular precursor cell-based therapy remain major challenges in the field.

Efficient Differentiation of TBX18+/WT1+ Epicardial-Like Cells from Human Pluripotent Stem Cells Using Small Molecular Compounds

The epicardium promotes neovascularization and cardiomyocyte regeneration by generating vascular smooth muscle cells (SMCs) and producing regenerative factors after adult heart infarction. It is therefore a potential cell resource for repair of the injured heart. However, the epicardium also participates in fibrosis and scarring of the injured heart, complicating its use in regenerative medicine. In this study, we report coexpression of TBX18 and WT1 in the majority of epicardial cells during mouse embryonic epicardial development. Furthermore, we describe a convenient chemically defined, immunogen-free, small molecule-based method for generating TBX18⁺/WT1⁺ epicardial-like cell populations with 80% homogeneity from human pluripotent stem cells by modulation of the WNT and retinoic acid signaling pathways. These epicardial-like cells exhibited characteristic epicardial cell morphology following passaging and differentiation into functional SMCs or cardiac fibroblast-like cells. Our findings add to existing understanding of human epicardial development and provide an efficient and stable method for generating both human epicardial-like cells and SMCs.

Irisin reverses platelet derived growth factor-BB-induced vascular smooth muscle cells phenotype modulation through STAT3 signaling pathway

Vascular smooth muscle cells (VSMCs) phenotype modulation toward a synthetic phenotype is the main cause of cardiovascular disease. As a newly discovered myokine, Irisin is thought to be a promising candidate for the treatment of metabolic disturbances, as well as cardiovascular disease. However, no evidence has been shown for the direct effect of Irisin on VSMCs phenotype modulation and its underling mechanisms. The aim of this study was to explore the effect of Irisin on VSMCs phenotype modulation and the mechanisms involved. In the present study, it was found that Irisin restored the PDGF-BB-induced VSMCs phenotype modulation which exhibited down-regulation of smooth muscle cells (SMC) expression and up-regulation of matrix synthesis related marker expression, as well as proliferative phenotype. Moreover, our research demonstrated that Irisin further activated STAT3 signaling pathways. Finally, by applying an STAT3 inhibitor, WP1066, we revealed the roles of STAT3 in the PDGF-BB-induced VSMCs phenotype modulation when they were treated with Irisin. Taken together, these results demonstrated that Irisin may play a crucial role in regulating VSMCs phenotype modulation via the STAT3 signaling pathway.

Multipotent adult progenitor cells on an allograft scaffold facilitate the bone repair process

Multipotent adult progenitor cells are a recently described population of stem cells derived from the bone marrow stroma. Research has demonstrated the potential of multipotent adult progenitor cells for treating ischemic injury and cardiovascular repair; however, understanding of multipotent adult progenitor cells in orthopedic applications remains limited. In this study, we evaluate the osteogenic and angiogenic capacity of multipotent adult progenitor cells, both in vitro and loaded onto demineralized bone matrix in vivo, with comparison to mesenchymal stem cells, as the current standard. When compared to mesenchymal stem cells, multipotent adult progenitor cells exhibited a more robust angiogenic protein release profile in vitro and developed more extensive vasculature within 2 weeks in vivo. The establishment of this vascular network is critical to the ossification process, as it allows nutrient exchange and provides an influx of osteoprogenitor cells to the wound site. In vitro assays confirmed the multipotency of multipotent adult progenitor cells along mesodermal lineages and demonstrated the enhanced expression of alkaline phosphatase and production of calcium-containing mineral deposits by multipotent adult progenitor cells, necessary precursors for osteogenesis. In combination with a demineralized bone matrix scaffold, multipotent adult progenitor cells demonstrated enhanced revascularization and new bone formation in vivo in an orthotopic defect model when compared to mesenchymal stem cells on demineralized bone matrix or demineralized bone matrix–only control groups. The potent combination of angiogenic and osteogenic properties provided by multipotent adult progenitor cells appears to create a synergistic amplification of the bone healing process. Our results indicate that multipotent adult progenitor cells have the potential to better promote tissue regeneration and healing and to be a functional cell source for use in orthopedic applications.

Combined endovascular coiling and intra-aneurysmal allogeneic mesenchymal stromal cell therapy for intracranial aneurysms in a rabbit model: a proof-of-concept study

OBJECTIVE

To assess the feasibility and efficacy of clinically translatable adjuvant mesenchymal stem/stromal cells (MSCs) therapy in improving the healing of coiled aneurysms in a rabbit elastase aneurysm model.

METHODS

Bone marrow-derived MSC populations were isolated from three rabbit donors in a serum-free environment and independently characterized to confirm their identity. Elastase-induced carotid aneurysms were created in nine New Zealand white rabbits. Each animal received one of the following treatments based on previous randomization: (1) coiling alone (control group); (2) coiling with an intra-aneurysmal injection of saline (vehicle group); and (3) coiling with an intra-aneurysmal injection of 5 million allogeneic MSCs (treatment group). The animals were followed for 4 weeks post-treatment, at the end of which blinded analyses of angiograms and histology were performed.

RESULTS

Histological results in the treatment group showed improvements over the control and vehicle groups, although the improvement over the vehicle group was not significant. Intra-aneurysmal cell therapy with 5 million allogeneic MSCs did not result in any major adverse events. Angiographic results did not show any significant difference among groups.

CONCLUSIONS

This proof-of-concept study shows that adjuvant MSC therapy for intracranial aneurysms is feasible and may enhance histological improvement of coiled aneurysms at 4 weeks post-treatment.

Key transcription factors in the differentiation of mesenchymal stem cells

Mesenchymal stem cells (MSCs) are multipotent cells that represent a promising source for regenerative medicine. MSCs are capable of osteogenic, chondrogenic, adipogenic and myogenic differentiation. Efficacy of differentiated MSCs to regenerate cells in the injured tissues requires the ability to maintain the differentiation toward the desired cell fate. Since MSCs represent an attractive source for autologous transplantation, cellular and molecular signaling pathways and micro-environmental changes have been studied in order to understand the role of cytokines, chemokines, and transcription factors on the differentiation of MSCs. The differentiation of MSC into a mesenchymal lineage is genetically manipulated and promoted by specific transcription factors associated with a particular cell lineage. Recent studies have explored the integration of transcription factors, including Runx2, Sox9, PPARγ, MyoD, GATA4, and GATA6 in the differentiation of MSCs. Therefore, the overexpression of a single transcription factor in MSCs may promote trans-differentiation into specific cell lineage, which can be used for treatment of some diseases. In this review, we critically discussed and evaluated the role of transcription factors and related signaling pathways that affect the differentiation of MSCs toward adipocytes, chondrocytes, osteocytes, skeletal muscle cells, cardiomyocytes, and smooth muscle cells.

piggyBac transposons expressing full-length human dystrophin enable genetic correction of dystrophic mesoangioblasts

Duchenne muscular dystrophy (DMD) is a genetic neuromuscular disorder caused by the absence of dystrophin. We developed a novel gene therapy approach based on the use of the piggyBac (PB) transposon system to deliver the coding DNA sequence (CDS) of either full-length human dystrophin (DYS: 11.1 kb) or truncated microdystrophins (MD1: 3.6 kb; MD2: 4 kb). PB transposons encoding microdystrophins were transfected in C2C12 myoblasts, yielding 65±2% MD1 and 66±2% MD2 expression in differentiated multinucleated myotubes. A hyperactive PB (hyPB) transposase was then deployed to enable transposition of the large-size PB transposon (17 kb) encoding the full-length DYS and green fluorescence protein (GFP). Stable GFP expression attaining 78±3% could be achieved in the C2C12 myoblasts that had undergone transposition. Western blot analysis demonstrated expression of the full-length human DYS protein in myotubes. Subsequently, dystrophic mesoangioblasts from a Golden Retriever muscular dystrophy dog were transfected with the large-size PB transposon resulting in 50±5% GFP-expressing cells after stable transposition. This was consistent with correction of the differentiated dystrophic mesoangioblasts following expression of full-length human DYS. These results pave the way toward a novel non-viral gene therapy approach for DMD using PB transposons underscoring their potential to deliver large therapeutic genes.

Vascular Smooth Muscle Cells From Hypertensive Patient-Derived Induced Pluripotent Stem Cells to Advance Hypertension Pharmacogenomics

Studies in hypertension (HTN) pharmacogenomics seek to identify genetic sources of variable antihypertensive drug response. Genetic association studies have detected single-nucleotide polymorphisms (SNPs) that link to drug responses; however, to understand mechanisms underlying how genetic traits alter drug responses, a biological interface is needed. Patient-derived induced pluripotent stem cells (iPSCs) provide a potential source for studying otherwise inaccessible tissues that may be important to antihypertensive drug response. The present study established multiple iPSC lines from an HTN pharmacogenomics cohort. We demonstrated that established HTN iPSCs can robustly and reproducibly differentiate into functional vascular smooth muscle cells (VSMCs), a cell type most relevant to vasculature tone control. Moreover, a sensitive traction force microscopy assay demonstrated that iPSC-derived VSMCs show a quantitative contractile response on physiological stimulus of endothelin-1. Furthermore, the inflammatory chemokine tumor necrosis factor α induced a typical VSMC response in iPSC-derived VSMCs. These studies pave the way for a large research initiative to decode biological significance of identified SNPs in hypertension pharmacogenomics.

SIGNIFICANCE

Treatment of hypertension remains suboptimal, and a pharmacogenomics approach seeks to identify genetic biomarkers that could be used to guide treatment decisions; however, it is important to understand the biological underpinnings of genetic associations. Mouse models do not accurately recapitulate individual patient responses based on their genetics, and hypertension-relevant cells are difficult to obtain from patients. Induced pluripotent stem cell (iPSC) technology provides a great interface to bring patient cells with their genomic data into the laboratory and to study hypertensive responses. As an initial step, the present study established an iPSC bank from patients with primary hypertension and demonstrated an effective and reproducible method of generating functional vascular smooth muscle cells.

Cell Therapy for Intracranial Aneurysms: A Review

One in five patients undergoing endovascular coiling (the current standard of care for treating intracranial aneurysms) experience a recurrence of the aneurysm as a result of improper healing. Recurrence remains the only major drawback of the coiling treatment and has been the focus of many studies over the last two decades. Cell therapy, a novel treatment modality in which therapeutic cells are introduced to the site of the injury to promote tissue regeneration, has opened up new possibilities for treating aneurysms. The healing response that ensues aneurysm embolization includes several cellular processes that can be targeted with cell therapy to prevent the aneurysm from recurring. Ten preclinical studies involving cell therapy to treat aneurysms were published between 1999 and 2014. In this review, we summarize the results of these studies and discuss advances, shortcomings, and the future of cell therapy for intracranial aneurysms.

Lentivirus Live Cell Array for Quantitative Assessment of Gene and Pathway Activation during Myogenic Differentiation of Mesenchymal Stem Cells

Stem cell differentiation involves multiple cascades of transcriptional regulation that govern the cell fate. To study the real-time dynamics of this complex process, quantitative and high throughput live cell assays are required. Herein, we developed a lentiviral library of promoters and transcription factor binding sites to quantitatively capture the gene expression dynamics over a period of several days during myogenic differentiation of human mesenchymal stem cells (MSCs) harvested from two different anatomic locations, bone marrow and hair follicle. Our results enabled us to monitor the sequential activation of signaling pathways and myogenic gene promoters at various stages of differentiation. In conjunction with chemical inhibitors, the lentiviral array (LVA) results also revealed the relative contribution of key signaling pathways that regulate the myogenic differentiation. Our study demonstrates the potential of LVA to monitor the dynamics of gene and pathway activation during MSC differentiation as well as serve as a platform for discovery of novel molecules, genes and pathways that promote or inhibit complex biological processes.

Functional states of resident vascular stem cells and vascular remodeling

Recent evidence indicates that different types of vascular stem cells (VSCs) reside within the mural layers of arteries and veins. The precise identities of these resident VSCs are still unclear; generally, postnatal vasculature contains multilineage stem cells and vascular cell lineage-specific progenitor/stem cells which may participate in both vascular repair and lesion formation. However, the underlying mechanism remains poorly understood. In this review, we summarize the potential molecular mechanisms, which may control the quiescence and activation of resident VSCs and highlight a notion that the differential states of resident VSCs are directly linked to vascular repair or lesion formation.

Multipotent Adult Progenitor Cells from Bone Marrow Differentiate into Chondrocyte-Like Cells

Cartilage tissue engineering has great potential for treating chondral and osteochondral injuries. Efficient seed cells are the key to cartilage tissue engineering. Multipotent adult progenitor cells (MAPCs) have greater differentiation ability than other bone-marrow stem cells, and thus may be candidate seed cells. We attempted to differentiate MAPCs into chondrocyte-like cells to evaluate their suitability as seed cells for cartilage tissue engineering. Toluidine blue and Alcian blue staining suggested that glycosaminoglycan was expressed in differentiated cells. Immunofluorostaining indicated that differentiated human MAPCs (hMAPCs) expressed collagen II. Based on these results, we concluded that bone-marrow-derived hMAPCs could differentiate into chondrocyte-like cells in vitro.

Inhibitory role of reactive oxygen species in the differentiation of multipotent vascular stem cells into vascular smooth muscle cells in rats: a novel aspect of traditional culture of rat aortic smooth muscle cells

Proliferative or synthetic vascular smooth muscle cells (VSMCs) are widely accepted to be mainly derived from the dedifferentiation or phenotypic modulation of mature contractile VSMCs, i.e., a phenotype switch from a normally quiescent and contractile type into a proliferative or synthetic form. However, this theory has been challenged by recent evidence that synthetic VSMCs predominantly originate instead from media-derived multipotent vascular stem cells (MVSCs). To test these hypotheses further, we re-examine whether the conventional rat aortic SMC (RASMC) culture involves the VSMC differentiation of MVSCs or the dedifferentiation of mature VSMCs and the potential mechanism for controlling the synthetic phenotype of RASMCs. We enzymatically isolated RASMCs and cultured the cells in both a regular growth medium (RGM) and a stem cell growth medium (SCGM). Regardless of culture conditions, only a small portion of freshly isolated RASMCs attaches, survives and grows slowly during the first 7 days of primary culture, while expressing both SMC- and MVSC-specific markers. RGM-cultured cells undergo a process of synthetic SMC differentiation, whereas SCGM-cultured cells can be differentiated into not only synthetic SMCs but also other somatic cells. Notably, compared with the RGM-cultured differentiated RASMCs, the SCGM-cultured undifferentiated cells exhibit the phenotype of MVSCs and generate greater amounts of reactive oxygen species (ROS) that act as a negative regulator of differentiation into synthetic VSMCs. Knockdown of phospholipase A2, group 7 (Pla2g7) suppresses ROS formation in the MVSCs while enhancing SMC differentiation of MVSCs. These results suggest that cultured synthetic VSMCs can be derived from the SMC differentiation of MVSCs with ROS as a negative regulator.

Cell Therapy for Stress Urinary Incontinence

Urinary incontinence (UI) is the involuntary loss of urine and is a common condition in middle-aged and elderly women and men. Stress urinary incontinence (SUI) is caused by leakage of urine when coughing, sneezing, laughing, lifting, and exercise, even standing leads to increased intra-abdominal pressure. Other types of UI also exist such as urge incontinence (also called overactive bladder), which is a strong and unexpected sudden urge to urinate, mixed forms of UI that result in symptoms of both urge and stress incontinence, and functional incontinence caused by reduced mobility, cognitive impairment, or neuromuscular limitations that impair mobility or dexterity. However, for many SUI patients, there is significant loss of urethral sphincter muscle due to degeneration of tissue, the strain and trauma of pregnancy and childbirth, or injury acquired during surgery. Hence, for individuals with SUI, a cell-based therapeutic approach to regenerate the sphincter muscle offers the advantage of treating the cause rather than the symptoms. We discuss current clinically relevant cell therapy approaches for regeneration of the external urethral sphincter (striated muscle), internal urethral sphincter (smooth muscle), the neuromuscular synapse, and blood supply. The use of mesenchymal stromal/stem cells is a major step in the right direction, but they may not be enough for regeneration of all components of the urethral sphincter. Inclusion of other cell types or biomaterials may also be necessary to enhance integration and survival of the transplanted cells.

Islet-1 overexpression in human mesenchymal stem cells promotes vascularization through monocyte chemoattractant protein-3

The LIM-homeobox transcription factor islet-1 (ISL1) has been proposed to mark a cardiovascular progenitor cell lineage that gives rise to cardiomyocytes, endothelial cells, and smooth muscle cells. The aim of this study was to investigate whether forced expression of ISL1 in human mesenchymal stem cells (hMSCs) influenced the differentiation capacity and angiogenic properties of hMSCs. The lentiviral vector, EF1α-ISL1, was constructed using the Multisite Gateway System and used to transduce hMSCs. We found that ISL1 overexpression did not alter the proliferation, migration, or survival of hMSCs or affect their ability to differentiate into osteoblasts, adipocytes, cardiomyocytes, or endotheliocytes. However, ISL1-hMSCs differentiated into smooth muscle cells more efficiently than control hMSCs. Furthermore, conditioned medium from ISL1-hMSCs greatly enhanced the survival, migration, and tube-formation ability of human umbilical vein endothelial cells (HUVECs) in vitro. In vivo angiogenesis assays also showed much more vascular-like structures in the group cotransplanted with ISL1-hMSCs and HUVECs than in the group cotransplanted with control hMSCs and HUVECs. Quantitative RT-PCR and antibody arrays detected monocyte chemoattractant protein-3 (MCP3) at a higher level in conditioned medium from ISL1-hMSCs cultures than in conditioned medium from control hMSCs. Neutralization assays showed that addition of an anti-MCP3 antibody to ISL1-hMSCs-conditioned medium efficiently abolished the angiogenesis-promoting effect of ISL1-hMSCs. Our data suggest that overexpression of ISL1 in hMSCs promotes angiogenesis in vitro and in vivo through increasing secretion of paracrine factors, smooth muscle differentiation ability, and enhancing the survival of HUVECs.

Regeneration of degenerated urinary sphincter muscles: improved stem cell-based therapies and novel imaging technologies

Stress urinary incontinence (SUI) is a largely ousted but significant medical, social, and economic problem. Surveys suggest that nowadays approximately 10% of the male and 15% of the female population suffer from urinary incontinence at some stage in their lifetime. In women, two major etiologies contribute to SUI: degeneration of the urethral sphincter muscle controlling the closing mechanism of the bladder outflow and changes in lower pelvic organ position associated with degeneration of connective tissue or with mechanical stress, including obesity and load and tissue injury during pregnancy and delivery. In males, the reduction of the sphincter muscle function is sometimes due to surgical interventions as a consequence of prostate cancer treatment, benign prostate hyperplasia, or of neuropathical origin. Accordingly, for women and men different therapies were developed. In some cases, SUI can be treated by physical exercise, electrophysiological stimulation, and pharmacological interventions. If this fails to improve the situation, surgical interventions are required. In standard procedures, endoprostheses for mechanical support of the weakened tissue or mechanical valves for a bladder outflow control are implanted. In 20% of cases treated, repeat procedures are required as implants yield all sorts of side effects in time. Based on preclinical studies, the application of an advanced therapy medicinal product (ATMP) such as implantation of autologous cells may be a curative and long-lasting therapy for SUI. Cellular therapy could also be an option for men suffering from incontinence caused by injury of the nerves controlling the muscular sphincter system. Here we briefly report on human progenitor cells, especially on mesenchymal stromal cells (MSCs), their expansion and differentiation to smooth muscle or striated muscle cells in vitro, labeling of cells for in vivo imaging, concepts of improved, precise, yet gentle application of cells in muscle tissue, and monitoring of injected cells in situ.

Induction of endometrial mesenchymal stem cells into tissue-forming cells suitable for fascial repair

Pelvic organ prolapse is a major hidden burden affecting almost one in four women. It is treated by reconstructive surgery, often augmented with synthetic mesh. To overcome the growing concerns of using current synthetic meshes coupled with the high risk of reoperation, a tissue engineering strategy has been developed, adopting a novel source of mesenchymal stem cells. These cells are derived from the highly regenerative endometrial lining of the uterus (eMSCs) and will be delivered in vivo using a new gelatin-coated polyamide scaffold. In this study, gelatin properties were optimized by altering the gelatin concentration and extent of crosslinking to produce the desired gelation and degradation rate in culture. Following cell seeding of uncoated polyamide (PA) and gelatin-coated meshes (PA+G), the growth rate of eMSCs on the PA+G scaffolds was more than that on the PA alone, without compromising cell shape. eMSCs cultured on the PA+G scaffold retained their phenotype, as demonstrated by W5C5/SUSD2 (eMSC-specific marker) immunocytochemistry. Additionally, eMSCs were induced to differentiate into smooth muscle cells (SMC), as shown by immunofluorescence for smooth muscle protein 22 and smooth muscle myosin heavy chain. eMSCs also differentiated into fibroblast-like cells when treated with connective tissue growth factor with enhanced detection of Tenascin-C and collagen type I as well as new tissue formation, as seen by Masson's trichrome. In summary, it was demonstrated that the PA+G scaffold is an appropriate platform for eMSC delivery, proliferation and differentiation into SMC and fibroblasts, with good biocompatibility and the capacity to regenerate neo-tissue.

Endothelial cells direct mesenchymal stem cells toward a smooth muscle cell fate

Under defined conditions, mesenchymal stem cells can differentiate into unique cell types, making them attractive candidates for cell-based disease therapies. Ischemic diseases would greatly benefit from treatments that include the formation of new blood vessels from mesenchymal stem cells. However, blood vessels are complex structures composed of endothelial cells and smooth muscle cells, and their assembly and function in a diseased environment is reliant upon joining with the pre-existing vasculature. Although endothelial cell/smooth muscle cell interactions are well known, how endothelial cells may influence mesenchymal stem cells and facilitate their differentiation has not been defined. Therefore, we sought to explore how endothelial cells might drive mesenchymal stem cells toward a smooth muscle fate. Our data show that cocultured endothelial cells induce smooth muscle cell differentiation in mesenchymal stem cells. Endothelial cells can promote a contractile phenotype, reduce proliferation, and enhance collagen synthesis and secretion. Our data show that Notch signaling is essential for endothelial cell-dependent differentiation, and this differentiation pathway is largely independent of growth factor signaling mechanisms.

Cell therapy for cardiac repair--lessons from clinical trials

The global impetus to identify curative therapies has been fuelled by the unmet needs of patients in the context of a growing heart failure pandemic. To date, regeneration trials in patients with cardiovascular disease have used stem-cell-based therapy in the period immediately after myocardial injury, in an attempt to halt progression towards ischaemic cardiomyopathy, or in the setting of congestive heart failure, to target the disease process and prevent organ decompensation. Worldwide, several thousand patients have now been treated using autologous cell-based therapy; the safety and feasibility of this approach has been established, pitfalls have been identified, and optimization procedures envisioned. Furthermore, the initiation of phase III trials to further validate the therapeutic value of cell-based regenerative medicine and address the barriers to successful clinical implementation has led to resurgence in the enthusiasm for such treatments among patients and health-care providers. In particular, poor definition of cell types used, diversity in cell-handling procedures, and functional variability intrinsic to autologously-derived cells have been identified as the main factors limiting adoption of cell-based therapies. In this Review, we summarize the experience obtained from trials of 'first-generation' cell-based therapy, and emphasize the advances in the purification and lineage specification of stem cells that have enabled the development of 'next-generation' stem-cell-based therapies targeting cardiovascular disease.

Monocyte/macrophage cytokine activity regulates vascular smooth muscle cell function within a degradable polyurethane scaffold

Tissue engineering strategies rely on the ability to promote cell proliferation and migration into porous biomaterial constructs, as well as to support specific phenotypic states of the cells in vitro. The present study investigated the use of released factors from monocytes and their derived macrophages (MDM) and the mechanism by which they regulate vascular smooth muscle cell (VSMC) response in a VSMC-monocyte co-culture system within a porous degradable polyurethane (D-PHI) scaffold. VSMCs cultured in monocyte/MDM-conditioned medium (MCM), generated from the culture of monocytes/MDM on D-PHI scaffolds for up to 28 days, similarly affected VSMC contractile marker expression, growth and three-dimensional migration when compared to direct VSMC-monocyte co-culture. Monocyte chemotactic protein-1 (MCP-1) and interleukin-6 (IL-6) were identified as two cytokines present in MCM, at concentrations that have previously been shown to influence VSMC phenotype. VSMCs cultured alone on D-PHI scaffolds and exposed to MCP-1 (5 ng ml(-1)) or IL-6 (1 ng ml(-1)) for 7 days experienced a suppression in contractile marker expression (with MCP-1 or IL-6) and increased growth (with MCP-1) compared to no cytokine medium supplementation. These effects were also observed in VSMC-monocyte co-culture on D-PHI. Neutralization of IL-6, but not MCP-1, was subsequently shown to decrease VSMC growth and enhance calponin expression for VSMC-monocyte co-cultures on D-PHI scaffolds for 7 days, implying that IL-6 mediates VSMC response in monocyte-VSMC co-cultures. This study highlights the use of monocytes and their derived macrophages in conjunction with immunomodulatory biomaterials, such as D-PHI, as agents for regulating VSMC response, and demonstrates the importance of monocyte/MDM-released factors, such as IL-6 in particular, in this process.

Platelets and smooth muscle cells affecting the differentiation of monocytes

Background

Atherosclerosis is characterised by the formation of plaques. Monocytes play a pivotal role in plaque development as they differentiate into foam cells, a component of the lipid core whilst smooth muscle cells (SMC) are the principal cell identified in the cap. Recently, the ability of monocytes to differentiate into a myriad of other cell types has been reported. In lieu of these findings the ability of monocytes to differentiate into SMCs/smooth muscle (SM)-like cells was investigated.

Method and Results

Human monocytes were co-cultured with platelets or human coronary aortic SMCs and then analysed to assess their differentiation into SMCs/SM-like cells. The differentiated cells expressed a number of SMC markers and genes as determined by immunofluorescence staining and quantitative polymerase chain reaction (qPCR). CD array analysis identified marker expression profiles that discriminated them from monocytes, macrophages and foam cells as well as the expression of markers which overlapped with fibroblast and mesenchymal cells. Electron microscopy studies identified microfilaments and increased amounts of rough endoplasmic reticulum indicative of the SM- like cells, fibroblasts.

Conclusions

In the appropriate environmental conditions, monocytes can differentiate into SM-like cells potentially contributing to cap formation and plaque stability. Thus, monocytes may play a dual role in the development of plaque formation and ultimately atherosclerosis.