Concise review: Adipose-derived stem cells as a novel tool for future regenerative medicine

Electroporation: A Sustainable and Cell Biology Preserving Cell Labeling Method for Adipogenous Mesenchymal Stem Cells

Human mesenchymal stem cells derived from adipose tissue (AD-hMSCs) represent a promising source for tissue engineering and are already widely used in cell therapeutic clinical trials. Until today, an efficient and sustainable cell labeling system for cell tracking does not exist. We evaluated transient transfection through electroporation for cell labeling and compared it with lentiviral transduction for AD-hMSCs. In addition, we tested whether nonsense DNA or a reporter gene such as enhanced green fluorescent protein (EGFP) is the more suitable label for AD-hMSCs. Using electroporation, the transfection efficiency reached a maximal level of 44.6 ± 1.1% EGFP-positive cells after selective and expansive cultivation of the mixed MSC population, and was 44.5 ± 1.4% after gene transfer with Cyanin3-marked nonsense-label DNA, which remained stable during 2 weeks of nonselective cultivation (37.2 ± 4.7% positive AD-hMSCs). Electroporation with both nonsense DNA and pEGFP-N1 led to a slight growth retardation of 45.2% and 59.1%, respectively. EGFP-transfected or transduced AD-hMSCs showed a limited adipogenic and osteogenic differentiation capacity, whereas it was almost unaffected in cells electroporated with the nonsense-label DNA. The nonsense DNA was detectable through quantitative real-time polymerase chain reaction for at least 5 weeks/10 passages and in differentiated AD-hMSCs. EGFP-labeled cells were trackable for 24 h in vitro and served as testing cells with new materials for dental implants for 7 days. In contrast, lentivirally transduced AD-hMSCs showed an altered natural immune phenotype of the AD-hMSCs with lowered expression of two cell type defining surface markers (CD44 and CD73) and a relevantly decreased cell growth by 71.8% as assessed by the number of colony-forming units. We suggest electroporation with nonsense DNA as an efficient and long-lasting labeling method for AD-hMSCs with the comparably lowest negative impact on the phenotype or the differentiation capacity of the cells, which may, therefore, be suitable for tissue engineering. In contrast, EGFP transfection by electroporation is efficient but may be more suitable for cell tracking within cell therapies without MSC differentiation procedures. Since current protocols of lentiviral gene transduction include the risk of cell biological alterations, electroporation seems advantageous and sustainable enough for hMSC labeling.

Comparative study of the neural differentiation capacity of mesenchymal stromal cells from different tissue sources: An approach for their use in neural regeneration therapies

Mesenchymal stem cells (MSCs) can trans/differentiate to neural precursors and/or mature neurons and promote neuroprotection and neurogenesis. The above could greatly benefit neurodegenerative disorders as well as in the treatment of post-traumatic and hereditary diseases of the central nervous system (CNS). In order to attain an ideal source of adult MSCs for the treatment of CNS diseases, adipose tissue, bone marrow, skin and umbilical cord derived MSCs were isolated and studied to explore differences with regard to neural differentiation capacity. In this study, we demonstrated that MSCs from several tissues can differentiate into neuron-like cells and differentially express progenitors and mature neural markers. Adipose tissue MSCs exhibited significantly higher expression of neural markers and had a faster proliferation rate. Our results suggest that adipose tissue MSCs are the best candidates for the use in neurological diseases.

Allogeneic ADSCs induce CD8 T cell-mediated cytotoxicity and faster cell death after exposure to xenogeneic serum or proinflammatory cytokines

This study examined the induction of recipient T-cell cytotoxicity after exposure to allogeneic adipose-derived mesenchymal stem cells (ADSCs). ADSCs pre-exposed to xenogeneic serum significantly induced cytotoxicity through CD8 T-cell granzyme B secretion after allogeneic antigen stimulation, and this effect was increased with prolonged reaction time. ADSCs pretreated with proinflammatory cytokines also induced cytotoxicity through granzyme B secretion and significantly increased human leukocyte antigen (HLA)-ABC expression. T-cell cytotoxicity towards ADSCs grown in xeno-free medium (XF-ADSCs) was lower than that towards ADSCs exposed to xenogeneic serum or proinflammatory cytokines, but XF-ADSCs still induced cytotoxicity. We further investigated the causes of T-cell cytotoxicity towards XF-ADSCs. XF-ADSC death was effectively inhibited by HLA-blocking antibodies, suggesting that ADSC HLAs are a major cause of alloreactive T-cell generation. These results indicated that culturing of allogeneic ADSCs with recipient serum may alleviate alloreactive CD8 T-cell cytotoxicity. Ultimately, development of therapeutic agents using autologous ADSCs would be a suitable way to avoid immunogenicity and CD8 T cell-mediated cytotoxicity, but more attention should be paid to the potential immunogenicity of allogeneic ADSCs, which could perhaps be mitigated through the use of immunosuppressants.

The conditions under which donor stem cells are cultured can limit attack by the recipient’s immune system after transplantation. Adult stem cells taken from donors who are genetically similar to recipients show promise as therapeutic agents for various conditions, from cardiac to immunity-related diseases. However, patients’ immune systems will often attack and destroy the transplanted cells. Chung-Gyu Park and Sung-Ho Chang at Seoul National University, South Korea, explored methods of growing stem cells so that they are less likely to be destroyed by the patient’s T-cells. The team found that human T-cells will attack stem cells grown in media containing bovine serum or those pre-treated with pro-inflammatory proteins. T-cell activity was weaker against stem cells grown in media with autologous serum.

Amputation-Site Soft-Tissue Restoration Using Adipose Stem Cell Therapy

Soft-tissue deficits in amputation stumps can lead to significant pain and disability. An emerging treatment option is stem cell-enriched fat grafting. This is the first study assessing the potential for this treatment modality in lower extremity amputation sites. In this prospective cohort study, five injured military personnel suffering from pain and limited function at amputation sites were recruited. Fat grafting enriched with stromal vascular fraction was performed at amputation sites to provide additional subcutaneous tissue padding over bony structures. Outcomes measures included complications, demographic data, physical examination, cellular subpopulations, cell viability, graft volume retention, pain, Lower Extremity Functional Scale, Functional Mobility Assessment, 36-Item Short-Form Health Survey, and rates of depression. Follow-up was 2 years. There were no significant complications. Volume retention was 61.5 ± 24.0 percent. Overall cell viability of the stromal vascular fraction was significantly correlated with volume retention (p = 0.016). There was no significant correlation between percentage of adipose-derived stem cells or number of cells in the stromal vascular fraction and volume retention. There was a nonsignificant trend toward improvement in pain scores (3.0 ± 2.5 to 1.2 ± 1.6; p = 0.180 at 2 years). There were no significant changes in disability indexes. Results from this pilot study demonstrate that stromal vascular fraction-enriched fat grafting is a safe, novel modality for the treatment of symptomatic soft-tissue defects in traumatic lower extremity amputations. Volume retention can be anticipated at slightly over 60 percent. Further studies are needed to assess efficacy. CLINICAL QUESTION/LEVEL OF EVIDENCE:: Therapeutic, IV.

Differentiation Capacity of Human Aortic Perivascular Adipose Progenitor Cells

Adipose tissue is a rich source of multi-potent mesenchymal stem cells (MSC) capable of differentiating into osteogenic, adipogenic, and chondrogenic lineages. Adipogenic differentiation of progenitor cells is a major mechanism driving adipose tissue expansion and dysfunction in response to obesity. Understanding changes to perivascular adipose tissue (PVAT) is thus clinically relevant in metabolic disease. However, previous studies have been predominately performed in the mouse and other animal models. This protocol uses human thoracic PVAT samples collected from patients undergoing coronary artery bypass graft surgery. Adipose tissue from the ascending aorta was collected and used for explantation of the stromal vascular fraction. We previously confirmed the presence of adipose progenitor cells in human PVAT with the capacity to differentiate into lipid-containing adipocytes. In this study, we further analyzed the differentiation potential of cells from the stromal vascular fraction, presumably containing multi-potent progenitor cells. We compared PVAT-derived cells to human bone marrow MSC for differentiation into adipogenic, osteogenic, and chondrogenic lineages. Following 14 days of differentiation, specific stains were utilized to detect lipid accumulation in adipocytes (Oil red O), calcific deposits in osteogenic cells (Alizarin Red), or glycosaminoglycans and collagen in chondrogenic cells (Masson's Trichrome). While bone marrow MSC efficiently differentiated into all three lineages, PVAT-derived cells had adipogenic and chondrogenic potential, but lacked robust osteogenic potential.

Neural Stem Cells Transfected with Reactive Oxygen Species-Responsive Polyplexes for Effective Treatment of Ischemic Stroke

Neural stem cells (NSCs), capable of ischemia-homing, regeneration, and differentiation, exert strong therapeutic potentials in treating ischemic stroke, but the curative effect is limited in the harsh microenvironment of ischemic regions rich in reactive oxygen species (ROS). Gene transfection to make NSCs overexpress brain-derived neurotrophic factor (BDNF) can enhance their therapeutic efficacy; however, viral vectors must be used because current nonviral vectors are unable to efficiently transfect NSCs. The first polymeric vector, ROS-responsive charge-reversal poly[(2-acryloyl)ethyl(p-boronic acid benzyl)diethylammonium bromide] (B-PDEA), is shown here, that mediates efficient gene transfection of NSCs and greatly enhances their therapeutics in ischemic stroke treatment. The cationic B-PDEA/DNA polyplexes can effectively transfect NSCs; in the cytosol, the B-PDEA is oxidized by intracellular ROS into negatively charged polyacrylic acid, quickly releasing the BDNF plasmids for efficient transcription and secreting a high level of BDNF. After i.v. injection in ischemic stroke mice, the transfected NSCs (BDNF-NSCs) can home to ischemic regions as efficiently as the pristine NSCs but more efficiently produce BDNF, leading to significantly augmented BDNF levels, which in turn enhances the mouse survival rate to 60%, from 0% (nontreated mice) or ≈20% (NSC-treated mice), and enables more rapid and superior functional reconstruction.

Enhanced osteoinduction of electrospun scaffolds with assemblies of hematite nanoparticles as a bioactive interface

Purpose

Electrospun scaffolds have been studied extensively for their potential use in bone tissue engineering. However, their hydrophobicity and relatively low matrix stiffness constrain their osteoinduction capacities. In the present study, we studied polymer electrospun scaffolds coated with hydrophilic hematite nanoparticles (αFeNPs) constructed using layer-by-layer (LbL) assembly to construct a bioactive interface between the scaffolds and cells, to improve the osteoinduction capacities of the scaffolds.

Materials and methods

The morphology of the αFeNPs was assessed. Surface properties of the scaffolds were tested by X-ray photoelectron spectroscopy (XPS), surface water contact angle, and in vitro protein adsorption test. The stiffness of the coating was tested using an atomic force microscope (AFM). In vitro cell assays were performed using rat adipose-derived stem cells (ADSCs).

Results

Morphology characterizations showed that αFeNPs assembled on the surface of the scaffold, where the nano assemblies improved hydrophilicity and increased surface roughness, with increased surface stiffness. Enhanced initial ADSC cell spread was found in the nano assembled groups. Significant enhancements in osteogenic differentiation, represented by enhanced alkaline phosphatase (ALP) activities, elevated expression of osteogenic marker genes, and increased mineral synthesis by the seeded ADSCs, were detected. The influencing factors were attributed to the better hydrophilicity, rougher surface topography, and harder interface stiffness. In addition, the presence of nanoparticles was believed to provide better cell adhesion sites.

Conclusion

The results suggested that the construction of a bioactive interface by LbL assembly using αFeNPs on traditional scaffolds should be a promising method for bone tissue engineering.

Microvesicles from human adipose stem cells promote wound healing by optimizing cellular functions via AKT and ERK signaling pathways

BACKGROUND

Human adipose stem cells (ASCs) have emerged as a promising treatment paradigm for skin wounds. Recent works demonstrate that the therapeutic effect of stem cells is partially mediated by extracellular vesicles, which comprise exosomes and microvesicles. In this study, we investigate the regenerative effects of isolated microvesicles from ASCs and evaluate the mechanisms how ASC microvesicles promote wound healing.

METHODS

Adipose stem cell-derived microvesicles (ASC-MVs) were isolated by differential ultracentrifugation, stained by PKH26, and characterized by electron microscopy and dynamic light scattering (DLS). We examined ASC-MV effects on proliferation, migration, and angiogenesis of keratinocytes, fibroblasts, and endothelial cells both in vitro and in vivo. Next, we explored the underlying mechanisms by gene expression analysis and the activation levels of AKT and ERK signaling pathways in all three kinds of cells after ASC-MV stimulation. We then assessed the effect of ASC-MVs on collagen deposition, neovascularization, and re-epithelialization in an in vivo skin injury model.

RESULTS

ASC-MVs could be readily internalized by human umbilical vein endothelial cells (HUVECs), HaCAT, and fibroblasts and significantly promoted the proliferation, migration, and angiogenesis of these cells both in vitro and in vivo. The gene expression of proliferative markers (cyclin D1, cyclin D2, cyclin A1, cyclin A2) and growth factors (VEGFA, PDGFA, EGF, FGF2) was significantly upregulated after ASC-MV treatment. Importantly, ASC-MVs stimulated the activation of AKT and ERK signaling pathways in those cells. The local injection of ASC-MVs at wound sites significantly increased the re-epithelialization, collagen deposition, and neovascularization and led to accelerated wound closure.

CONCLUSIONS

Our data suggest that ASC-MVs can stimulate HUVEC, HaCAT, and fibroblast functions. ASC-MV therapy significantly accelerates wound healing, and the benefits of ASC-MVs may due to the involvement of AKT and ERK signaling pathways. This illustrates the therapeutic potential of ASC-MVs which may become a novel treatment paradigm for cutaneous wound healing.

Quantitative analysis of F-actin alterations in adherent human mesenchymal stem cells: Influence of slow-freezing and vitrification-based cryopreservation

Cryopreservation is an essential tool to meet the increasing demand for stem cells in medical applications. To ensure maintenance of cell function upon thawing, the preservation of the actin cytoskeleton is crucial, but so far there is little quantitative data on the influence of cryopreservation on cytoskeletal structures. For this reason, our study aims to quantitatively describe cryopreservation induced alterations to F-actin in adherent human mesenchymal stem cells, as a basic model for biomedical applications. Here we have characterised the actin cytoskeleton on single-cell level by calculating the circular standard deviation of filament orientation, F-actin content, and average filament length. Cryo-induced alterations of these parameters in identical cells pre and post cryopreservation provide the basis of our investigation. Differences between the impact of slow-freezing and vitrification are qualitatively analyzed and highlighted. Our analysis is supported by live cryo imaging of the actin cytoskeleton via two photon microscopy. We found similar actin alterations in slow-frozen and vitrified cells including buckling of actin filaments, reduction of F-actin content and filament shortening. These alterations indicate limited functionality of the respective cells. However, there are substantial differences in the frequency and time dependence of F-actin disruptions among the applied cryopreservation strategies; immediately after thawing, cytoskeletal structures show least disruption after slow freezing at a rate of 1°C/min. As post-thaw recovery progresses, the ratio of cells with actin disruptions increases, particularly in slow frozen cells. After 120 min of recovery the proportion of cells with an intact actin cytoskeleton is higher in vitrified than in slow frozen cells. Freezing at 10°C/min is associated with a high ratio of impaired cells throughout the post-thawing culture.

Endothelial Differentiated Adipose-Derived Stem Cells Improvement of Survival and Neovascularization in Fat Transplantation

Background

Adipose-derived stem cells (ASCs) assisted lipotransfer have been considered to facilitate the survival of fat grafts. However, emerging evidence of insufficient vascularization is another obstacle for fat graft survival in cell-assisted lipotransfer.

Objectives

This study evaluated if endothelial phenotype ASCs with fat lipoaspirate improves survival and neovascularization in fat transplantation.

Methods

ASCs were isolated from human periumbilical fat tissue and cultured in endothelial growth medium for 2 weeks. Fat lipoaspirate was mixed with fresh adipose stroma vascular fraction (SVF), endothelial differentiated ASCs (EC/ASCs), and fat lipoaspirate alone. Three fat mixtures were subcutaneously injected into the adult male Sprague-Dawley rat's dorsum at 3 locations. At 8 weeks after transplantation, the grafted fat lipoaspirates were harvested, and the extracted fat was evaluated using photographic, survival weights measurements and histological examination. Neo-vascularization was quantified by immunofluorescence and real-time RT-PCR.

Results

Grafts from the EC/ASC assisted group had a higher survival rate, morphologic integrity, and most uniform lipid droplets. They also revealed less inflammation and fibrosis with increased number of vessels by histological and immunofluorescence analysis. Quantitative RT-PCR analysis indicated that the expression levels of EC-specific markers of CD31 and vWF were higher in the EC/ASC group compared with in the control and fat with SVF transplants.

Conclusions

These results indicated that co-implantation of fat lipoaspirate with ASCs differentiated toward an endothelial phenotype improves both survival and neovascularization of the transplanted fat lipoaspirate, which might provide benefits and represents a promising strategy for clinical application in autologous fat transplantation.

In vivo fate of free and encapsulated iron oxide nanoparticles after injection of labelled stem cells

Nanoparticle contrast agents are useful tools to label stem cells and monitor the in vivo bio-distribution of labeled cells in pre-clinical models of disease. In this context, understanding the in vivo fate of the particles after injection of labelled cells is important for their eventual clinical use as well as for the interpretation of imaging results. We examined how the formulation of superparamagnetic iron oxide nanoparticles (SPIONs) impacts the labelling efficiency, magnetic characteristics and fate of the particles by comparing individual SPIONs with polyelectrolyte multilayer capsules containing SPIONs. At low labelling concentration, encapsulated SPIONs served as an efficient labelling agent for stem cells. The bio-distribution after intra-cardiac injection of labelled cells was monitored longitudinally by MRI and as an endpoint by inductively coupled plasma-optical emission spectrometry. The results suggest that, after being released from labelled cells after cell death, both formulations of particles are initially stored in liver and spleen and are not completely cleared from these organs 2 weeks post-injection.

Review of surgical resection and reconstruction in head and neck cancer. Traditional versus current concepts

This review summarizes the development of head and neck cancer resection and reconstruction. The developments in the treatment of cancer patients are reflected in their surgical outcomes, in addition to functional and aesthetic improvements. New technologies, such as surgical simulation and planning, minimally invasive surgery, and microsurgery have been added to the field to improve surgical resection of the tumor and reconstruction. The field is still growing to optimize the management of head and neck cancer.

Relative contributions of adipose-resident CD146+ pericytes and CD34+ adventitial progenitor cells in bone tissue engineering

Pericytes and other perivascular stem/stromal cells are of growing interest in the field of tissue engineering. A portion of perivascular cells are well recognized to have MSC (mesenchymal stem cell) characteristics, including multipotentiality, self-renewal, immunoregulatory functions, and diverse roles in tissue repair. Here, we investigate the differential but overlapping roles of two perivascular cell subsets in paracrine induction of bone repair. CD146+CD34-CD31-CD45-pericytes and CD34+CD146-CD31-CD45-adventitial cells were derived from human adipose tissue and applied alone or in combination to calvarial bone defects in mice. In vitro, osteogenic differentiation and tubulogenesis assays were performed using either fluorescence activated cell sorting-derived CD146+ pericytes or CD34+ adventitial cells. Results showed that CD146+ pericytes induced increased cord formation in vitro and angiogenesis in vivo in comparison with patient-matched CD34+ adventitial cells. In contrast, CD34+ adventitial cells demonstrated heightened paracrine-induced osteogenesis in vitro. When applied in a critical-size calvarial defect model in NOD/SCID mice, the combination treatment of CD146+ pericytes with CD34+ adventitial cells led to greater re-ossification than either cell type alone. In summary, adipose-derived CD146+ pericytes and CD34+ adventitial cells display functionally distinct yet overlapping and complementary roles in bone defect repair. Consequently, CD146+ pericytes and CD34+ adventitial cells may demonstrate synergistic bone healing when applied as a combination cellular therapy.

Conversion of human adipose-derived stem cells into functional and expandable endothelial-like cells for cell-based therapies

Background

Ischemic vascular diseases are the major cause of death worldwide. In recent years, endothelial cell (EC)-based approaches to vascular regeneration are increasingly viable strategies for treating ischemic diseases, but their applications are challenged by the difficulties in their efficient generation and stable maintenance. Here, we show an alternative protocol that facilitates the generation of functional and expandable ETS variant 2 (ETV2)-induced endothelial-like cells (EiECs) from human adipose-derived stem cells (hADSCs), providing a potential source of cells for autologous ECs to treat ischemic vascular diseases.

Methods

hADSCs were obtained from fresh human adipose tissue. Passage 3 hADSCs were transduced with doxycycline (DOX)-inducible ETV2 transcription factor; purified ETV2-hADSCs were induced into endothelial-like cells using a two-stage induction culture system composed of small molecule compounds and cell factors. EiECs were evaluated for their surface markers, proliferation, gene expression, secretory capacity, and effects on vascular regeneration in vivo.

Results

We found that short-term ETV2 expression combined with TGF-β inhibition is sufficient for the generation of kinase insert domain receptor (KDR)+ cells from hADSCs within 10 days. KDR+ cells showed immature endothelial characteristics, and they can gradually mature in a chemically defined induction medium at the second stage of induction. Futher studies showed that KDR+ cells deriving EC-like cells could stably self-renew and expand about 10⁶-fold in 1 month, and they exhibited expected genome-wide molecular features of mature ECs. Functionally, these EC-like cells significantly promoted revascularization in a hind limb ischemic model.

Conclusions

We isolated highly purified hADSCs and effectively converted them into functional and expandable endothelial-like cells. Thus, the study may provide an alternative strategy to obtain functional EC-like cells with potential for biomedical and pharmaceutical applications.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-1088-6) contains supplementary material, which is available to authorized users.

Stem Cells Derived from Lipoma and Adipose Tissue-Similar Mesenchymal Phenotype but Different Differentiation Capacity Governed by Distinct Molecular Signature

Lipomas are benign adipose tissue tumors of unknown etiology, which can vary in size, number, body localization and cell populations within the tissue. Lipoma-derived stem cells (LDSCs) are proposed as a potential tool in regenerative medicine and tissue engineering due to their similar characteristics with adipose-derived stem cells (ADSCs) reported so far. Our study is among the first giving detailed insights into the molecular signature and differences in the differentiation capacity of LDSCs in vitro compared to ADSCs. Mesenchymal stem cell phenotype was analyzed by gene expression and flow cytometric analysis of stem cell markers. Adipogenesis and osteogenesis were analyzed by microscopic analysis, cytochemical and immunocytochemical staining, gene and protein expression analyses. We showed that both LDSCs and ADSCs were mesenchymal stem cells with similar phenotype and stemness state but different molecular basis for potential differentiation. Adipogenesis-related genes expression pattern and presence of more mature adipocytes in ADSCs than in LDSCs after 21 days of adipogenic differentiation, indicated that differentiation capacity of LDSCs was significantly lower compared to ADSCs. Analysis of osteogenesis-related markers after 16 days of osteogenic differentiation revealed that both types of cells had characteristic osteoblast-like phenotype, but were at different stages of osteogenesis. Differences observed between LDSCs and ADSCs are probably due to the distinct molecular signature and their commitment in the tissue that governs their different capacity and fate during adipogenic and osteogenic induction in vitro despite their similar mesenchymal phenotype.

Comparison of the regenerative effect of adipose-derived stem cells, fibrin glue scaffold, and autologous bone graft in experimental mandibular defect in rabbit

BACKGROUND/AIMS

One of the main concerns for maxillofacial and orthopedic surgeons is finding a method to improve regeneration of large craniofacial bone defects. The aim of this study was to investigate the healing and regenerative effects of fibrin glue associated with adipose-derived stem cells (ADSCs) and fibrin glue scaffold alone with autologous bone grafts in experimental mandibular defects of the rabbit.

METHODS

Bilateral uni-cortical osteotomies were performed in the mandible of 20 male Dutch rabbits. The animals were randomly divided into 2 equal groups. In one group, the defect on the right side was treated by fibrin glue associated with ADSCs and the defect on the other side remained as the control. In another group, the defect on the right side was treated with fibrin glue and on the left side with autologous bone graft. After 28 and 56 days, five rabbits from each group were evaluated by computed tomography (CT) and histopathological examinations.

RESULTS

Coronal CT showed a remarkable reconstruction of cortical bone in the fibrin glue associated with ADSCs group at 28 and 56 days post-surgery. Histopathologically, new cortical bony bridge formation was seen increasingly in the fibrin glue, fibrin glue associated with ADSCs, and autologous bone graft groups after 28 days. Statistical analysis of the thickness of new cortical bone in the treatment versus control groups showed a significant difference between fibrin glue alone and fibrin glue associated with ADSCs groups (P = 0.02). No significant difference was found between the fibrin glue associated with ADSCs and the autologous bone graft groups (P > 0.05).

CONCLUSIONS

The healing process had a significant increase in the thickness of new cortical bone when fibrin glue scaffold associated with ADSCs was used.

Mesenchymal stem cell dysfunction in diabetes

Diabetes mellitus (DM) is a chronic disease that results in a variety of systemic complications. Recently, stem cell-based therapies have been proposed as potential modalities to manage DM related complications. Mesenchymal stem cell (MSC) based therapies are often considered as an ideal stem cell-based treatment for DM management due to their immunosuppressive characteristics, anti-inflammatory properties and differentiation potential. While MSCs show tremendous promise, the underlying functional deficits of MSCs in DM patients is not well understood. Using the MEDLINE database to define these functional deficits, our search yielded 1826 articles of which 33 met our inclusion criteria. This allowed us to review the topic and illuminate four major molecular categories by which MSCs are compromised in both Type 1 DM and Type II DM models which include: (1) changes in angiogenesis/vasculogenesis, (2) altered pro-inflammatory cytokine secretion, (3) increased oxidative stress markers and (4) impaired cellular differentiation and decreased proliferation. Knowledge of the deficits in MSC function will allow us to more clearly assess the efficacy of potential biologic therapies for reversing these dysfunctions when treating the complications of diabetic disease.

Prevascularization of collagen-glycosaminoglycan scaffolds: stromal vascular fraction versus adipose tissue-derived microvascular fragments

Background

The seeding of scaffolds with the stromal vascular fraction (SVF) of adipose tissue is a common prevascularization strategy in tissue engineering. Alternatively, adipose tissue-derived microvascular fragments (ad-MVF) may serve as vascularization units. In contrast to SVF single cells, they represent a mixture of intact arteriolar, capillary and venular vessel segments. Therefore, we herein hypothesized that the ad-MVF-based prevascularization of scaffolds is superior to the conventional SVF single cells-based approach.

Results

SVF single cells and ad-MVF were enzymatically isolated from epididymal fat pads of green fluorescent protein (GFP)⁺ donor mice to assess their viability and cellular composition using fluorescence microscopy and flow cytometry. Moreover, collagen-glycosaminoglycan matrices (Integra®) were seeded with identical amounts of the isolates and implanted into full-thickness skin defects within dorsal skinfold chambers of GFP⁻ recipient mice for the intravital fluorescent microscopic, histological and immunohistochemical analysis of implant vascularization and incorporation throughout an observation period of 2 weeks. Non-seeded matrices served as controls. While both isolates contained a comparable fraction of endothelial cells, perivascular cells, adipocytes and stem cells, ad-MVF exhibited a significantly higher viability. After in vivo implantation, the vascularization of ad-MVF-seeded scaffolds was improved when compared to SVF-seeded ones, as indicated by a significantly higher functional microvessel density. This was associated with an enhanced cellular infiltration, collagen content and density of CD31⁺/GFP⁺ microvessels particularly in the center of the implants, demonstrating a better incorporation into the surrounding host tissue. In contrast, non-seeded matrices exhibited a poor vascularization, incorporation and epithelialization over time.

Conclusions

The present study demonstrates that ad-MVF are highly potent vascularization units that markedly accelerate and improve scaffold vascularization when compared to the SVF.

Electronic supplementary material

The online version of this article (10.1186/s13036-018-0118-3) contains supplementary material, which is available to authorized users.

A review: therapeutic potential of adipose-derived stem cells in cutaneous wound healing and regeneration

As the most important barrier for the human body, the skin often suffers from acute and chronic injuries, especially refractory wounds, which seriously affect the quality of life of patients. For these refractory wounds that cannot be cured by various surgical methods, stem cell transplantation becomes an effective research direction. As one of the adult stem cells, adipose-derived stem cells play an indispensable role in the repair of skin wounds more than other stem cells because of their advantages such as immune compatibility and freedom from ethical constraints. Here, we actively explore the role of adipose-derived stem cells in the repair of cutaneous wound and conclude that it can significantly promote cutaneous wound healing and regeneration. Based on a large number of animal and clinical trials, we believe that adipose-derived stem cells will have a greater breakthrough in the field of skin wound repair in the future, especially in chronic refractory wounds.

Hydrogels in adipose tissue engineering-Potential application in post-mastectomy breast regeneration

Current methods of breast reconstruction are associated with significant shortcomings, including capsular contracture, infection, rupture, the need for reoperation in implant-based reconstruction, and donor site morbidity in autologous reconstruction. These limitations result in severe physical and psychological issues for breast cancer patients. Recently, research has moved into the field of adipose tissue engineering to overcome these limitations. A wide range of regenerative strategies has been devised utilising various scaffold designs and biomaterials. A scaffold capable of providing appropriate biochemical and biomechanical cues for adipogenesis is required. Hydrogels have been widely studied for their suitability for adipose tissue regeneration and are advantageous secondary to their ability to accurately imitate the native extracellular matrix. The aim of this review was to analyse the use of hydrogel scaffolds in the field of adipose tissue engineering.

Adipose Stem Cell Translational Applications: From Bench-to-Bedside

During the last five years, there has been a significantly increasing interest in adult adipose stem cells (ASCs) as a suitable tool for translational medicine applications. The abundant and renewable source of ASCs and the relatively simple procedure for cell isolation are only some of the reasons for this success. Here, we document the advances in the biology and in the innovative biotechnological applications of ASCs. We discuss how the multipotential property boosts ASCs toward mesenchymal and non-mesenchymal differentiation cell lineages and how their character is maintained even if they are combined with gene delivery systems and/or biomaterials, both in vitro and in vivo.

WISP-1 drives bone formation at the expense of fat formation in human perivascular stem cells

The vascular wall within adipose tissue is a source of mesenchymal progenitors, referred to as perivascular stem/stromal cells (PSC). PSC are isolated via fluorescence activated cell sorting (FACS), and defined as a bipartite population of pericytes and adventitial progenitor cells (APCs). Those factors that promote the differentiation of PSC into bone or fat cell types are not well understood. Here, we observed high expression of WISP-1 among human PSC in vivo, after purification, and upon transplantation in a bone defect. Next, modulation of WISP-1 expression was performed, using WISP-1 overexpression, WISP-1 protein, or WISP-1 siRNA. Results demonstrated that WISP-1 is expressed in the perivascular niche, and high expression is maintained after purification of PSC, and upon transplantation in a bone microenvironment. In vitro studies demonstrate that WISP-1 has pro-osteogenic/anti-adipocytic effects in human PSC, and that regulation of BMP signaling activity may underlie these effects. In summary, our results demonstrate the importance of the matricellular protein WISP-1 in regulation of the differentiation of human stem cell types within the perivascular niche. WISP-1 signaling upregulation may be of future benefit in cell therapy mediated bone tissue engineering, for the healing of bone defects or other orthopaedic applications.

Substrate elasticity regulates adipose-derived stromal cell differentiation towards osteogenesis and adipogenesis through β-catenin transduction

It is generally recognised that mesenchymal stem cells (MSCs) can differentiate into multiple lineages through guidance from the biophysical properties of the substrates. However, the precise biophysical mechanism that enables MSCs to respond to substrate properties remains unclear. In the current study, polydimethylsiloxane (PDMS) substrates with different stiffnesses were fabricated and the way in which the elastic modulus of the substrate regulated differentiation towards osteogenesis and adipogenesis in adipose-derived stromal cells (ASCs) was explored. Initially, a cell morphology change by SEM was observed between the stiff and soft substrates. The cytoskeleton stains including microfilament by F-actin and microtubule by α- and β-tubulin further showed a larger cell spreading area on the stiff substrate. Then the expression of vinculin, in charge for the linkage of adhesion molecules to the actin cytoskeleton, was enhanced on the stiff substrate. This change in focal adhesion plaque further triggered intracellular β-catenin signaling and promoted its nuclear translocation especially on the stiff substrate. The influence of β-catenin signaling on direct differentiation to osteogenic lineages was through direct binding between its downstream protein, Lef-1, and the osteogenic transcriptional factors, Runx2 and Osx, while on differentiation to adipogenic lineages was through modulating the expression of PPARγ. The imbalance of stiffness-induced β-catenin signaling finally induced a stronger osteogenesis and a weaker adipogenesis on the stiff substrate relative to those on the soft substrate. This study indicates the importance of stiffness on ASC differentiation and could help to increase understanding of the mechanism underlying molecular signal transduction from mechanosensing, mechanotransducing to stem cell differentiation.

STATEMENT OF SIGNIFICANCE

Mesenchymal stem cells can differentiate into multiple lineages, such as adipogenesis, myogenesis, neurogenesis, angiogenesis and osteogenesis, through influence of biophysical properties of the extracellular matrix. However, the precise bio-mechanism that triggers stem cell differentiation in response to matrix biophysical properties remains unclear. In the current study, we provide a series of experiments involving the characterization of cell morphology, microfilament, microtubule and adhesion capacity of adipose-derived stromal cells (ASCs) in response to substrate stiffness, and further elucidation of cytoplasmic β-catenin-dependent signal transduction, nuclear translocation and resultant promoter activation of transcriptional factors for osteogenesis and adipogenesis. This study provides an explanation on deeper understanding of bio-mechanism underlying substrate stiffness-triggered β-catenin signal transduction from active mechanosensing, mechanotransducing to stem cell differentiation.

Infrapatellar Fat Pad-Derived Stem Cell-Based Regenerative Strategies in Orthopedic Surgery

Infrapatellar fat pad is a densely vascularized and innervated extrasynovial tissue that fills the anterior knee compartment. It plays a role in knee biomechanics as well as constitutes a source of stem cells for regeneration after knee injury. Infrapatellar fat pad-derived stem cells (IPFP-ASCs) possess enhanced and age-independent differentiation capacity as compared to other stem cells, which makes them a very promising candidate in stem cell-based regenerative therapy. The aims of this review are to outline the latest advances and potential trends in using IPFP-ASCs and to emphasize the advantages over other sources of stem cells for applications in orthopedic surgery.

Intra-Articular Injection of Bone Marrow-Derived Mesenchymal Stem Cells Leading to Better Clinical Outcomes without Difference in MRI Outcomes from Baseline in Patients with Knee Osteoarthritis

Purpose

Bone marrow (BM) is frequently used as a source of mesenchymal stem cells (MSCs) because they have a high potential for differentiation. However, it is unclear whether BM-derived MSCs lead to better clinical and magnetic resonance imaging (MRI) outcomes postoperatively.

Materials and Methods

This meta-analysis compared the clinical and MRI outcomes in patients with knee osteoarthritis (OA) treated with BM-derived MSCs. Eight studies comparing the clinical and MRI outcomes assessed with various measurement tools in patients with knee OA treated with BM-derived MSCs were included.

Results

The range of motion (95% confidence interval [CI], −13.05 to 4.24; p=0.32) and MRI outcomes (95% CI, −0.16 to 1.40; p=0.12) did not differ significantly between the baseline and final follow-up. In contrast, pain (95% CI, 0.89 to 1.87; p<0.001) and functional outcomes (95% CI, 0.70 to 2.07; p<0.001) were significantly improved at the final follow-up when compared to the baseline.

Conclusions

This meta-analysis found no significant difference in the tested range of motion and MRI outcomes between the baseline and the final follow-up in patients treated with BM-derived MSCs, whereas significant functional improvement and pain relief were noted when compared with the baseline. Thus, BM-derived MSCs appear to be a viable alternative for patients with knee OA, although long-term and high-quality randomized controlled trials are needed to confirm the clinical benefits.

Evaluation of the effects of adipose-derived mesenchymal stem cells on intraperitoneal adhesions

OBJECTIVES

The goal was to examine the efficiency of local implementation of adipose-derived mesenchymal stem cells, which have an anti-inflammatory effect, in preventing the intra-abdominal adhesions in rats.

MATERIAL AND METHODS

Twenty-one Wistar albino rats were randomly divided into 3 groups, 7 rats in each: Group 1 was defined as the control group, Group 2 as the sham group, and Group 3 as the adipose-derived mesenchymal stem cell group. A 6 cm mid-abdomen incision in the all the rats was performed. The cecum serosa and sub-serosa were injured by rubbing with a gauze. No agent was applied intraperitoneally for the rats in Group 1; 1.5 mL saline and 2x10⁶/kg allojenic adipose-derived mesenchymal stem cells in the 1.5 mL saline were injected into peritoneum of rats in Groups 2 and 3, respectively. Laparotomy was performed on the 14^th day. Adhesion scores, histopathological examination, E-cadherin expression, and the tissue hydroxyproline level were evaluated.

RESULTS

The general adhesion score and collagen deposition in Group 3 were found to be significantly higher than in Groups 1 and 2 (p=0.003 and p=0.009, respectively). In the inflammatory cell comparison, a significant decrease was found in Group 3 in proportion to Groups 1 and 2 (p=0.001, p=0.005, respectively). The E-cadherin levels were found to be higher in Group 3 (p=0.003).

CONCLUSION

Severe adhesion was observed in the adipose-derived mesenchymal stem cells group. Collagen intensity and E-Cadherin expression also increased in the adipose-derived mesenchymal stem cells group. The anti-inflammatory effect was also seen in the adipose-derived mesenchymal stem cells group.

Recellularization of decellularized adipose tissue-derived stem cells: role of the cell-secreted extracellular matrix in cellular differentiation

Adipose-derived stem cells (ASCs) are found in a location within the adipose tissue known as the stem cell niche. The ASCs in the niche are maintained in the quiescent state, and upon exposure to various microenvironmental triggers are prompted to undergo proliferation or differentiation. These microenvironmental triggers also modulate the extracellular matrix (ECM), which interacts with the cells through the cytoskeleton and induces downstream events inside the cells that bring about a change in cell behaviour. In response to these changes, the cells remodel the ECM, which will differ according to the type of tissue being formed by the cells. As the ECM itself plays an important role in the regulation of cellular differentiation, this study aims to explore the role of the cell-secreted ECM at various stages of differentiation of stem cells in triggering the differentiation of ASCs. To this end, the ASCs cultured in proliferation, osteogenic and adipogenic media were decellularized and the secreted ECM was characterized. Overall, it was found that osteo-differentiated ASCs produced higher amounts of collagen and glycosaminoglycans (GAG) compared to the undifferentiated and adipo-differentiated ASCs. The two types of differentiated ECMs were subsequently shown to trigger initial but not terminal differentiation of ASCs into osteo- and adipo-lineages respectively, as indicated by the upregulation of lineage specific markers. In addition, integrin subunits alpha (α) 6 and integrin beta (β) 1 were found to be produced by ASCs cultured on cell-secreted ECM-coated substrates, suggesting that the integrins α6 and β1 play an instrumental role in cell-ECM interactions. Taken together, this study demonstrates the importance of the ECM in cellular fate decisions and how ECM-coated substrates can potentially be used for various tissue engineering applications.

Adipose-Derived Mesenchymal Stem Cells: A New Tool for the Treatment of Renal Fibrosis

As chronic kidney disease progresses, kidney tissue inevitably undergoes cell loss, accumulation of extracellular matrix, and kidney tissue fibrosis, eventually leading to end-stage renal disease. With the continuous innovation of cell therapy technology, mesenchymal stem cells are used in numerous fields, including cardiovascular diseases, diabetes, and kidney tissue injury repair. Adipose-derived mesenchymal stem cells (AMSCs), a type of pluripotent stem cells, have the potential for self-renewal and proliferation with low immunogenicity and significant anti-inflammatory properties. AMSCs can promote impaired cell regeneration and remodeling in renal lesions, thus avoiding further worsening of renal disease and even blocking or reversing the process of renal fibrosis. In this review, we discuss the mechanisms involved in the treatment of renal fibrosis with AMSCs and summarize the potential hazards that may exist in cell therapy.

Nanotopographical cues of electrospun PLLA efficiently modulate non-coding RNA network to osteogenic differentiation of mesenchymal stem cells during BMP signaling pathway

Application of stem cells in combination with nanofibrous substrates is an interesting biomimetic approach for enhanced regeneration of damaged tissues such as bone and cartilage. The investigation of the complex interplay between nanotopographical cues of niche and noncoding RNAs in stem cells fate is an effective tool to find a new strategy for enhancing the induction of osteogenesis. In this study, we investigated the effects of aligned and random orientations of nanofibers as a natural ECM-mimicking environment on the network of noncoding RNA in mesenchymal stem cells. Aligned and randomly oriented Ploy (L-lactide) PLLA scaffolds were fabricated via electrospinning. Human Adipose Tissue-Derived Mesenchymal Stem Cells (hASCs) were isolated from adipose tissue and were cultured on surfaces of these scaffolds. Their capacity to support hMSCs proliferation was also investigated by MTT assay and the expression of c-Myc gene. Then, after 7, 14 and 21 days, the osteogenic commitment of hMSCs and the miRNA regulatory network in BMP signaling pathway were evaluated by measuring alkaline phosphatase (ALP) activity, extracellular calcium deposition, and bone-related gene activation by Real-Time PCR. Furthermore, osteogenic differentiation was evaluated with regard to their noncoding RNA network. Our results for the first time showed an interaction between nanotopographical cues and miRNA activity in hMSCs. We found that the nanotopographical cues could be used to influence the osteogenic differentiation process of hMSCs through the modulation of lncRNAs and miR-125b as negative regulators of osteogenesis as well as the H19 modulator BMP signaling pathway that acts as a miRNA sponge. Moreover, we also demonstrated for the first time that MEG3 as a long noncoding RNA is controlled by miR-125b and microRNA-triggered lncRNA decay mechanism. This strategy seems to be an important tool for controlling stem cell fate in engineered tissues and provide new insights into most biocompatible scaffolds for bone-graft substitutes.

Histone demethylase JMJD6 regulates cellular migration and proliferation in adipose-derived mesenchymal stem cells

BACKGROUND

Adipose-derived mesenchymal stem cells (ADSCs) have been extensively explored as a promising therapeutic agent due to their differentiation, proliferation and migration abilities. The epigenetic mechanisms that regulate the fate of mesenchymal stem cells (MSCs) have been described in detail. However, the epigenetic modulation of ADSCs proliferation and migration is poorly understood.

METHODS

The present study examined histone demethylases roles and expression by RT-PCR, as well as through siRNA screening and ChIP-qPCR assay. Cellular proliferation and migration assays were employed in shRNA-mediated JMJD6 knockdown and control ADSCs. PDE1C inhibition studies were conducted to confirm its role in JMJD6-mediated epigenetic regulation of ADSCs.

RESULTS

The data demonstrate that the histone demethylase JMJD6 plays a critical role in regulating the proliferation and migration of ADSCs by removing H4R3me2a at the promoter regions of PDEC1 and suppressing PDEC1 expression. Importantly, the depletion of JMJD6 in ADSCs significantly increased cellular proliferation and motility, which was associated with increases in PDE1C expression and decreases in the levels of both cAMP and cGMP. The increase in proliferation and migration was reversed by treatment with a PDE1C inhibitor, suggesting that JMJD6 attenuates the proliferation and migration of ADSCs as an epigenetic regulator and PDE1C partially contributes to the JMJD6-mediated regulation.

CONCLUSIONS

Taken together, our results indicate for the first time that JMJD6 plays an important role in the regulation of ADSCs proliferation and migration through the modulation of PDE1C expression.

Immunophenotyping and transcriptional profiling of in vitro cultured human adipose tissue derived stem cells

Adipose-derived stem cells (ASCs) have become an important research model in regenerative medicine. However, there are controversies regarding the impact of prolonged cell culture on the ASCs phenotype and their differentiation potential. Hence, we studied 10 clinical ASCs replicates from plastic and oncological surgery patients, in six-passage FBS supplemented cultures. We quantified basic mesenchymal cell surface marker transcripts and the encoded proteins after each passage. In parallel, we investigated the differentiation potential of ASCs into chondrocytes, osteocytes and adipocytes. We further determined the effects of FBS supplementation and subsequent deprivation on the whole transcriptome by comprehensive mRNA and miRNA sequencing. Our results show that ASCs maintain differentiation potential and consistent profile of key mesenchymal markers, with apparent expression of distinct isoforms, in long-term cultures. No significant differences were observed between plastic and oncological surgery cohorts. ASCs in FBS supplemented primary cultures are almost committed to mesenchymal lineages as they express key epithelial-mesenchymal transition genes including early mesenchymal markers. Furthermore, combined mRNA/miRNA expression profiling strongly supports a modulatory role for the miR-30 family in the commitment process to mesenchymal lineages. Finally, we propose improvements to existing qPCR based assays that address alternative isoform expression of mesenchymal markers.

Stem cell therapy for faecal incontinence: Current state and future perspectives

Faecal continence is a complex function involving different organs and systems. Faecal incontinence is a common disorder with different pathogeneses, disabling consequences and high repercussions for quality of life. Current management modalities are not ideal, and the development of new treatments is needed. Since 2008, stem cell therapies have been validated, 36 publications have appeared (29 in preclinical models and seven in clinical settings), and six registered clinical trials are currently ongoing. Some publications have combined stem cells with bioengineering technologies. The aim of this review is to identify and summarise the existing published knowledge of stem cell utilization as a treatment for faecal incontinence. A narrative or descriptive review is presented. Preclinical studies have demonstrated that cellular therapy, mainly in the form of local injections of muscle-derived (muscle derived stem cells or myoblasts derived from them) or mesenchymal (bone-marrow- or adipose-derived) stem cells, is safe. Cellular therapy has also been shown to stimulate the repair of both acute and subacute anal sphincter injuries, and some encouraging functional results have been obtained. Stem cells combined with normal cells on bioengineered scaffolds have achieved the successful creation and implantation of intrinsically-innervated anal sphincter constructs. The clinical evidence, based on adipose-derived stem cells and myoblasts, is extremely limited yet has yielded some promising results, and appears to be safe. Further investigation in both animal models and clinical settings is necessary to drawing conclusions. Nevertheless, if the preliminary results are confirmed, stem cell therapy for faecal incontinence may well become a clinical reality in the near future.

Stem Cells in Dentistry: Types of Intra- and Extraoral Tissue-Derived Stem Cells and Clinical Applications

Stem cells are undifferentiated cells, capable of renewing themselves, with the capacity to produce different cell types to regenerate missing tissues and treat diseases. Oral facial tissues have been identified as a source and therapeutic target for stem cells with clinical interest in dentistry. This narrative review report targets on the several extraoral- and intraoral-derived stem cells that can be applied in dentistry. In addition, stem cell origins are suggested in what concerns their ability to differentiate as well as their particular distinguishing quality of convenience and immunomodulatory for regenerative dentistry. The development of bioengineered teeth to replace the patient's missing teeth was also possible because of stem cell technologies. This review will also focus our attention on the clinical application of stem cells in dentistry. In recent years, a variety of articles reported the advantages of stem cell-based procedures in regenerative treatments. The regeneration of lost oral tissue is the target of stem cell research. Owing to the fact that bone imperfections that ensue after tooth loss can result in further bone loss which limit the success of dental implants and prosthodontic therapies, the rehabilitation of alveolar ridge height is prosthodontists' principal interest. The development of bioengineered teeth to replace the patient's missing teeth was also possible because of stem cell technologies. In addition, a “dental stem cell banking” is available for regenerative treatments in the future. The main features of stem cells in the future of dentistry should be understood by clinicians.

Methods of Isolation, Characterization and Expansion of Human Adipose-Derived Stem Cells (ASCs): An Overview

Considering the increasing interest in adipose-derived stem cells (ASCs) in regenerative medicine, optimization of methods aimed at isolation, characterization, expansion and evaluation of differentiation potential is critical to ensure (a) the quality of stem cells also in terms of genetic stability; (b) the reproducibility of beneficial effects; and (c) the safety of their use. Numerous studies have been conducted to understand the mechanisms that regulate ASC proliferation, growth and differentiation, however standard protocols about harvesting and processing techniques are not yet defined. It is also important to note that some steps in the procedures of harvesting and/or processing have been reported to affect recovery and/or the physiology of ASCs. Even considering the great opportunity that the ASCs provide for the identification of novel molecular targets for new or old drugs, the definition of homogeneous preparation methods that ensure adequate quality assurance and control, in accordance with current GMPs (good manufacturing practices), is required. Here, we summarize the literature reports to provide a detailed overview of the methodological issues underlying human ASCs isolation, processing, characterization, expansion, differentiation techniques, recalling at the same time their basilar principles, advantages and limits, in particular focusing on how these procedures could affect the ASC quality, functionality and plasticity.

Adipose-derived and bone marrow mesenchymal stem cells: a donor-matched comparison

Background

Adipose-derived stem cells (ASCs) have been introduced as an alternative to bone marrow mesenchymal stem cells (BMSCs) for cell-based therapy. However, different studies comparing ASCs and BMSCs have shown conflicting results. In fact, harvesting ASCs and BMSCs from different individuals might influence the results, making comparison difficult. Therefore, this study aimed to characterize donor-matched ASCs and BMSCs in order to investigate proliferation, differentiation potential and possible effects of donor variation on these mesenchymal stem cells (MSCs).

Methods

Human bone marrow and adipose tissue samples were obtained from nine donors aged 8–14. ASCs and BMSCs were isolated and characterized based on expression of surface markers using flow cytometry. The proliferation up to 21 days was investigated. Multi-lineage differentiation was induced using osteogenic, chondrogenic and adipogenic differentiation media. Alkaline phosphatase (ALP) activity was monitored and collagen type I formation was evaluated by immunofluorescence staining. In vitro multi-potency was studied using tissue-specific stains and lineage-specific gene expression. In addition, the osteogenic lineage was evaluated at protein level.

Results

Isolated ASCs and BMSCs from all donors demonstrated morphologic and immunophenotypic characteristics of MSCs, with expression of MSCs markers and negative expression of hematopoietic markers. Unlike BMSCs, ASCs showed high expression of CD49d and low expression of Stro-1. In general, ASCs showed significantly higher proliferation and adipogenic capacity with more lipid vesicle formation and expression of the adipogenesis-related genes than BMSCs. In contrast, BMSCs showed significantly higher osteogenic and chondrogenic capacity compared to ASCs. BMSCs had earlier and higher ALP activity, calcium deposition, and expression of the osteogenesis- and chondrogenesis-related genes and the osteogenesis-related protein osteopontin. Proliferation and differentiation capacity of ASCs and BMSCs varied significantly among the donors.

Conclusions

ASCs and BMSCs showed tissue-specific differentiation abilities, but with significant variation between donors. The similarities and differences in the properties of ASCs and BMSCs should be taken into consideration when planning stem cell-based therapy.

Fas-L promotes the stem cell potency of adipose-derived mesenchymal cells

Fas-L is a TNF family member known to trigger cell death. It has recently become evident that Fas-L can transduce also non-apoptotic signals. Mesenchymal stem cells (MSCs) are multipotent cells that are derived from various adult tissues. Although MSCs from different tissues display common properties they also display tissue-specific characteristics. Previous works have demonstrated massive apoptosis following Fas-L treatment of bone marrow-derived MSCs both in vitro and following their administration in vivo. We therefore set to examine Fas-L-induced responses in adipose-derived stem cells (ASCs). Human ASCs were isolated from lipoaspirates and their reactivity to Fas-L treatment was examined. ASCs responded to Fas-L by simultaneous apoptosis and proliferation, which yielded a net doubling of cell quantities and a phenotypic shift, including reduced expression of CD105 and increased expression of CD73, in association with increased bone differentiation potential. Treatment of freshly isolated ASCs led to an increase in large colony forming unit fibroblasts, likely produced by early stem cell progenitor cells. Fas-L-induced apoptosis and proliferation signaling were found to be independent as caspase inhibition attenuated Fas-L-induced apoptosis without impacting proliferation, whereas inhibition of PI3K and MEK, but not of JNK, attenuated Fas-L-dependent proliferation, but not apoptosis. Thus, Fas-L signaling in ASCs leads to their expansion and phenotypic shift toward a more potent stem cell state. We speculate that these reactions ensure the survival of ASC progenitor cells encountering Fas-L-enriched environments during tissue damage and inflammation and may also enhance ASC survival following their administration in vivo.

Recent review of the effect of nanomaterials on stem cells

The field of stem-cell-therapy offers considerable promise as a means of delivering new treatments for a wide range of diseases. Recent progress in nanotechnology has stimulated the development of multifunctional nanomaterials (NMs) for stem-cell-therapy. Several clinical trials based on the use of NMs are currently underway for stem-cell-therapy purposes, such as drug/gene delivery and imaging. However, the interactions between NMs and stem cells are far from being completed, and the effects of the NMs on cellular behavior need critical evaluation. In this review, the interactions between several types of mostly used NMs and stem cells, and their associated possible mechanisms are systematically discussed, with specific emphasis on the possible differentiation effects induced by NMs. It is expected that the enhanced understanding of NM-stem cell interactions will facilitate biomaterial design for stem-cell-therapy and regenerative medicine applications.

Camptothecin-loaded fusogenic nanodroplets as ultrasound theranostic agent in stem cell-mediated drug-delivery system

Adipose-derived stem cells (ADSCs) have been utilized in cellular delivery systems to carry therapeutic agents into tumors by migration. Drug-loaded nanodroplets release drugs and form bubbles after acoustic droplet vaporization (ADV) triggered by ultrasound stimulation, providing a system for ultrasound-induced cellular delivery of theranostic agents. In order to improve the efficiency of drug release, fusogenic nanodroplets were designed to go from nano to micron size upon uptake by ADSCs for reducing ADV threshold. The purpose of our study was to demonstrate the utility of camptothecin-loaded fusogenic nanodroplets (CPT-FNDs) as ultrasound theranostic agents in an ADSCs delivery system. CPT-FNDs showed an increase in size from 81.6 ± 3.5 to 1043.5 ± 28.3 nm and improved CPT release from 22.0 ± 1.8% to 37.6 ± 2.1%, demonstrating the fusion ability of CPT-FNDs. CPT-FNDs-loaded ADSCs demonstrated a cell viability of 77 ± 4%, and the in vitro migration ability was 3.2 ± 1.2-fold for the tumor condition compared to the cell growth condition. Ultrasound enhancement imaging showed intratumoral ADV-generated bubble formation (increasing 3.24 ± 0.47 dB) triggered by ultrasound after CPT-FNDs-loaded ADSCs migration into B16F0 tumors. Histological images revealed intratumoral distribution of CPT-FNDs-loaded ADSCs and tissue damage due to the ADV. The CPT-FNDs can be used as theranostic agents in an ADSCs delivery system to provide the ultrasound contrast imaging and deliver combination therapy of drug release and physical damage after ADV.

Liver regeneration during the associating liver partition and portal vein ligation for staged hepatectomy procedure in Sus scrofa is positively modulated by stem cells

This present study investigated the impact of the application of stem cells to liver regeneration following the first stage of associating liver partition and portal vein ligation for staged hepatectomy (ALPPS). The experiment was conducted on a pig model (n=6, 3 that did not receive application of stem cells, 3 that received application stem cells). Collected samples of liver (day 0 and 9 following surgery) were subjected to complete transcriptome sequencing. In total, 39 differentially expressed genes were found in the group without the application of the stem cells (genes of unwanted processes such as fibrosis and inflammation). In the group that did receive application of stem cells, no significantly differentially expressed genes were found, indicating a properly regenerated liver remnant. The present study therefore demonstrated, to the best of our knowledge for the first time, the positive effect of stem cells application in the liver regeneration process during ALPPS procedure in the pig model.

Comparison of mouse brown and white adipose‑derived stem cell differentiation into pacemaker‑like cells induced by TBX18 transduction

The present study aimed to compare brown adipose-derived stem cell (BASC) and white adipose-derived stem cell (WASC) differentiation into pacemaker‑like cells following T‑box (TBX)18 transduction. Mouse BASCs and WASCs were induced to differentiate into pacemaker‑like cells by adenovirus‑TBX18 transduction in vitro. The transduction rate was determined by fluorescence microscopy and cell ultrastructural changes were observed by transmission electron microscopy at 48 h post‑transduction. The mRNA and protein expression of pacemaker cell‑associated markers, including TBX18, TBX3, sarcomeric α‑actinin (Sr) and hyperpolarization‑activated cyclic nucleotide‑gated channel 4 (HCN4), were detected by reverse transcription‑quantitative polymerase chain reaction, immunofluorescence staining and western blot analysis. The results demonstrated that no significant difference was observed in the transduction rate between BASCs and WASCs. The ultrastructure of BASCs was observed to be more complex than that of WASCs, indicating that BASCs may possess a better structural foundation to differentiate into pacemaker‑like cells. TBX18, TBX3, Sr and HCN4 mRNA and protein expression in differentiated stem cells was significantly increased compared with the respective control groups. Furthermore, the expression levels were significantly higher in TBX18‑BASCs compared with TBX18‑WASCs. In conclusion, TBX18 gene transduction may facilitate the differentiation of BASCs and WASCs into pacemaker‑like myocardial cells, and BASCs may have a higher capacity than WASCs for this differentiation. TBX18 gene may therefore act as an efficient candidate in cell transplantation therapy for diseases and for future research into the cardiovascular system.

Uncultivated stromal vascular fraction is equivalent to adipose-derived stem and stromal cells on porous polyurethrane scaffolds forming adipose tissue in vivo

OBJECTIVES/HYPOTHESIS

To find an alternative approach to contemporary techniques in tissue augmentation and reconstruction, tissue engineering strategies aim to involve adipose-derived stem and stromal cells (ASCs) harboring a strong differentiation potential into various tissue types such as bone, cartilage, and fat.

STUDY DESIGN

Animal research.

METHODS

The stromal vascular fraction (SVF) was used directly as a cell source to provide a potential alternative to contemporary ASC-based adipose tissue engineering. Seeded in TissuCol fibrin, we applied ASCs or SVF cells to porous, degradable polyurethane (PU) scaffolds.

RESULTS

We successfully demonstrated the in vivo generation of volume-stable, well-vascularized PU-based constructs containing host-derived mature fat pads. Seeded human stem cells served as modulators of host-cell migration rather than differentiating themselves. We further demonstrated that preliminary culture of SVF cells was not necessary.

CONCLUSIONS

Our results bring adipose tissue engineering, together with automated processing devices, closer to clinical applicability. The time-consuming and cost-intensive culture and induction of the ASCs is not necessary.

LEVEL OF EVIDENCE

NA. Laryngoscope, 128:E206-E213, 2018.

Exosomes From Adipose-Derived Stem Cells Attenuate Adipose Inflammation and Obesity Through Polarizing M2 Macrophages and Beiging in White Adipose Tissue

Adipose-derived stem cells (ADSCs) play critical roles in controlling obesity-associated inflammation and metabolic disorders. Exosomes from ADSCs exert protective effects in several diseases, but their roles in obesity and related pathological conditions remain unclear. In this study, we showed that treatment of obese mice with ADSC-derived exosomes facilitated their metabolic homeostasis, including improved insulin sensitivity (27.8% improvement), reduced obesity, and alleviated hepatic steatosis. ADSC-derived exosomes drove alternatively activated M2 macrophage polarization, inflammation reduction, and beiging in white adipose tissue (WAT) of diet-induced obese mice. Mechanistically, exosomes from ADSCs transferred into macrophages to induce anti-inflammatory M2 phenotypes through the transactivation of arginase-1 by exosome-carried active STAT3. Moreover, M2 macrophages induced by ADSC-derived exosomes not only expressed high levels of tyrosine hydroxylase responsible for catecholamine release, but also promoted ADSC proliferation and lactate production, thereby favoring WAT beiging and homeostasis in response to high-fat challenge. These findings delineate a novel exosome-mediated mechanism for ADSC-macrophage cross talk that facilitates immune and metabolic homeostasis in WAT, thus providing potential therapy for obesity and diabetes.