Characterization of human mesenchymal stem cell secretome at early steps of adipocyte and osteoblast differentiation

Towards standardization of human adipose-derived stromal cells secretomes

The secretome of adipose-derived stromal cells (ASC) is a heterogeneous mixture of components with a beneficial influence on cellular microenvironments. As such, it represents a cell-free alternative in regenerative medicine therapies. Pathophysiological conditions increase the therapeutic capacity of ASC and, with this, the benefits of the secretome. Such conditions can be partially mimicked in vitro by adjusting culturing conditions. Secretomics, the unbiased analysis of a cell secretome by mass spectrometry, is a powerful tool to describe the composition of ASC secretomes. In this proteomics databases review, we compared ASC secretomic studies to retrieve persistently reported proteins resulting from the most explored types of culturing conditions used in research, i.e., exposure to normoxia, hypoxia, or cytokines. Our comparisons identified only eight common proteins within ASC normoxic secretomes, no commonalities within hypoxic ASC secretomes, and only nine within secretomes of ASC exposed to proinflammatory cytokines. Within these, and regardless of the culturing condition that stimulated secretion, a consistent presence of extracellular matrix-related pathways associated with such proteins was identified. Confounders such as donors' age, sex, body mass index, the anatomical area where ASC were harvested, secretome collection method, data description, and how the data is shared with the scientific community are discussed as factors that might explain our outcomes. We conclude that standardization is imperative as the currently available ASC secretomic studies do not facilitate solid conclusions on the therapeutic value of different ASC secretomes.

Cartilage lesion size and number of stromal vascular fraction (SVF) cells strongly influenced the SVF implantation outcomes in patients with knee osteoarthritis

PURPOSE

This study evaluated outcomes in patients with knee osteoarthritis following stromal vascular fraction implantation and assessed the associated prognostic factors.

METHODS

We retrospectively evaluated 43 patients who underwent follow-up magnetic resonance imaging 12 months after stromal vascular fraction implantation for knee osteoarthritis. Pain was assessed using the visual analogue scale and measured at baseline and 1-, 3-, 6-, and 12-month follow-up appointments. In addition, cartilage repair was evaluated based on the Magnetic Resonance Observation of Cartilage Repair Tissue scoring system using the magnetic resonance imaging from the 12-month follow-up. Finally, we evaluated the effects of various factors on outcomes following stromal vascular fraction implantation.

RESULTS

Compared to the baseline value, the mean visual analogue scale score significantly and progressively decreased until 12 months post-treatment (P < 0.05 for all, except n.s. between the 1 and 3-month follow-ups). The mean Magnetic Resonance Observation of Cartilage Repair Tissue score was 70.5 ± 11.1. Furthermore, the mean visual analogue scale and Magnetic Resonance Observation of Cartilage Repair Tissue scores significantly correlated 12 months postoperatively (P = 0.002). Additionally, the cartilage lesion size and the number of stromal vascular fraction cells significantly correlated with the 12-month visual analogue scale scores and the Magnetic Resonance Observation of Cartilage Repair Tissue score. Multivariate analyses determined that the cartilage lesion size and the number of stromal vascular fraction cells had a high prognostic significance for unsatisfactory outcomes.

CONCLUSION

Stromal vascular fraction implantation improved pain and cartilage regeneration for patients with knee osteoarthritis. The cartilage lesion size and the number of stromal vascular fraction cells significantly influenced the postoperative outcomes. Thus, these findings may serve as a basis for preoperative surgical decisions.

LEVEL OF EVIDENCE

IV.

Proteogenomic Analysis Reveals Proteins Involved in the First Step of Adipogenesis in Human Adipose-Derived Stem Cells

Background

Obesity is characterized as a disease that directly affects the whole-body metabolism and is associated with excess fat mass and several related comorbidities. Dynamics of adipocyte hypertrophy and hyperplasia play an important role in health and disease, especially in obesity. Human adipose-derived stem cells (hASC) represent an important source for understanding the entire adipogenic differentiation process. However, little is known about the triggering step of adipogenesis in hASC. Here, we performed a proteogenomic approach for understanding the protein abundance alterations during the initiation of the adipogenic differentiation process.

Methods

hASC were isolated from adipose tissue of three donors and were then characterized and expanded. Cells were cultured for 24 hours in adipogenic differentiation medium followed by protein extraction. We used shotgun proteomics to compare the proteomic profile of 24 h-adipogenic, differentiated, and undifferentiated hASC. We also used our previous next-generation sequencing data (RNA-seq) of the total and polysomal mRNA fractions of hASC to study posttranscriptional regulation during the initial steps of adipogenesis.

Results

We identified 3420 proteins out of 48,336 peptides, of which 92 proteins were exclusively identified in undifferentiated hASC and 53 proteins were exclusively found in 24 h-differentiated cells. Using a stringent criterion, we identified 33 differentially abundant proteins when comparing 24 h-differentiated and undifferentiated hASC (14 upregulated and 19 downregulated, respectively). Among the upregulated proteins, we shortlisted several adipogenesis-related proteins. A combined analysis of the proteome and the transcriptome allowed the identification of positive correlation coefficients between proteins and mRNAs.

Conclusions

These results demonstrate a specific proteome profile related to adipogenesis at the beginning (24 hours) of the differentiation process in hASC, which advances the understanding of human adipogenesis and obesity. Adipogenic differentiation is finely regulated at the transcriptional, posttranscriptional, and posttranslational levels.

Dlx5 Represses the Transcriptional Activity of PPARγ

Peroxisome proliferator-activated receptor gamma (PPARγ) is a master transcription factor in adipocyte differentiation, while distal-less homeobox 5 (Dlx5) is essential for initiating osteoblast differentiation by driving Runt-related transcription factor 2 expression. Considering that adipocytes and osteoblasts share common progenitors, there is a reciprocal correlation between bone and fat formation. However, the mechanism by which Dlx5 controls PPARγ remains unclear. We elucidated that Dlx5 physically binds to PPARγ during immunoprecipitation; in particular, the ligand-binding and DNA-binding domains of PPARγ were involved in the interaction. Transcriptional activity of PPARγ was significantly decreased by Dlx5 overexpression, whereas the opposite results were detected with Dlx5 knockdown. Rosiglitazone, a PPARγ agonist, further enhanced the PPARγ-induced transcriptional activity; however, Dlx5 overexpression effectively repressed the rosiglitazone-mediated increase in activity. Finally, DNA-binding affinity assay revealed that Dlx5 interrupts the interaction of PPARγ with the PPARγ response element promoter. In conclusion, our findings indicate that Dlx5 impedes PPARγ-induced activity, and it may be useful for managing diabetes drug-mediated obesity.

Adipose-PAS interactions in the context of its localised bio-engineering potential (Review)

Adipocytes are a known source of stem cells. They are easy to harvest, and are a suitable candidate for autogenous grafts. Adipose derived stem cells (ADSCs) have multiple target tissues which they can differentiate into, including bone and cartilage. In adipose tissue, ADSCs are able to differentiate, as well as providing energy and a supply of cytokines/hormones to manage the hypoxic and lipid/hormone saturated adipose environment. The plasminogen activation system (PAS) controls the majority of proteolytic activities in both adipose and wound healing environments, allowing for rapid cellular migration and tissue remodelling. While the primary activation pathway for PAS occurs through the urokinase plasminogen activator (uPA), which is highly expressed by endothelial cells, its function is not limited to enabling revascularisation. Proteolytic activity is dependent on protease activation, localisation, recycling mechanisms and substrate availability. uPA and uPA activated plasminogen allows pluripotent cells to arrive to new local environments and fulfil the niche demands. However, overstimulation, the acquisition of a migratory phenotype and constant protein turnover can be unconducive to the formation of structured hard and soft tissues. To maintain a suitable healing pattern, the proteolytic activity stimulated by uPA is modulated by plasminogen activator inhibitor 1. Depending on the physiological settings, different parts of the remodelling mechanism are activated with varying results. Utilising the differences within each microenvironment to recreate a desired niche is a valid therapeutic bio-engineering approach. By controlling the rate of protein turnover combined with a receptive stem cell lineage, such as ADSC, a novel avenue on the therapeutic opportunities may be identified, which can overcome limitations, such as scarcity of stem cells, low angiogenic potential or poor host tissue adaptation.

The secretome of mesenchymal stem cells and oxidative stress: challenges and opportunities in cell-free regenerative medicine

Over the last decade, mesenchymal stem cells (MSCs) have been considered a suitable source for cell-based therapy, especially in regenerative medicine. First, the efficacy and functions of MSCs in clinical applications have been attributed to their differentiation ability, called homing and differentiation. However, it has recently been confirmed that MSCs mostly exert their therapeutic effects through soluble paracrine bioactive factors and extracellular vesicles, especially secretome. These secreted components play critical roles in modulating immune responses, improving the survival, and increasing the regeneration of damaged tissues. The secretome content of MSCs is variable under different conditions. Oxidative stress (OS) is one of these conditions that is highly important in MSC therapy and regenerative medicine. High levels of reactive oxygen species (ROS) are produced during isolation, cell culture, and transplantation lead to OS, which induces cell death and apoptosis and limits the efficacy of their regeneration capability. In turn, the preconditioning of MSCs in OS conditions contributes to the secretion of several proteins, cytokines, growth factors, and exosomes, which can improve the antioxidant potential of MSCs against OS. This potential of MSC secretome has turned it into a new promising cell-free tissue regeneration strategy.This review provides a view of MSC secretome under OS conditions, focusing on different secretome contents of MSCs and thier possible therapeutic potential against cell therapy.

Naturally-derived protein extract from Gryllus bimaculatus improves antioxidant properties and promotes osteogenic differentiation of hBMSCs

Naturally-derived proteins or peptides are promising biopolymers for tissue engineering applications owing to their health-promoting activity. Herein, we extracted proteins (~90%) from two-spotted cricket (Gryllus bimaculatus) and evaluated their osteoinductive potential in human bone marrow-derived mesenchymal stem cells (hBMSCs) under in vitro conditions. The extracted protein isolate was analyzed for the amino acid composition and the mass distribution of the constituent peptide fraction. Fourier transform infrared (FTIR) spectroscopy was used to determine the presence of biologically significant functional groups. The cricket protein isolate (CPI) exhibited characteristic protein peaks in the FTIR spectrum. Notably, an enhanced cell viability was observed in the presence of the extracted proteins, showing their biocompatibility. The CPI also exhibited antioxidant properties in a concentration-dependent manner. More significant mineralization was observed in the CPI-treated cells than in the control, suggesting their osteoinductive potential. The upregulation of the osteogenic marker genes (Runx2, ALP, OCN, and BSP) in CPI treated media compared with the control supports their osteoinductive nature. Therefore, cricket-derived protein isolates could be used as functional protein isolate for tissue engineering applications, especially for bone regeneration.

Therapeutic Biomaterial Approaches to Alleviate Chronic Limb Threatening Ischemia

Chronic limb threatening ischemia (CLTI) is a severe condition defined by the blockage of arteries in the lower extremities that leads to the degeneration of blood vessels and is characterized by the formation of non-healing ulcers and necrosis. The gold standard therapies such as bypass and endovascular surgery aim at the removal of the blockage. These therapies are not suitable for the so-called "no option patients" which present multiple artery occlusions with a likelihood of significant limb amputation. Therefore, CLTI represents a significant clinical challenge, and the efforts of developing new treatments have been focused on stimulating angiogenesis in the ischemic muscle. The delivery of pro-angiogenic nucleic acid, protein, and stem cell-based interventions have limited efficacy due to their short survival. Engineered biomaterials have emerged as a promising method to improve the effectiveness of these latter strategies. Several synthetic and natural biomaterials are tested in different formulations aiming to incorporate nucleic acid, proteins, stem cells, macrophages, or endothelial cells in supportive matrices. In this review, an overview of the biomaterials used alone and in combination with growth factors, nucleic acid, and cells in preclinical models is provided and their potential to induce revascularization and regeneration for CLTI applications is discussed.

Therapeutic Potential of Mesenchymal Stromal Cells and Extracellular Vesicles in the Treatment of Radiation Lesions-A Review

Ionising radiation-induced normal tissue damage is a major concern in clinic and public health. It is the most limiting factor in radiotherapy treatment of malignant diseases. It can also cause a serious harm to populations exposed to accidental radiation exposure or nuclear warfare. With regard to the clinical use of radiation, there has been a number of modalities used in the field of radiotherapy. These includes physical modalities such modified collimators or fractionation schedules in radiotherapy. In addition, there are a number of pharmacological agents such as essential fatty acids, vasoactive drugs, enzyme inhibitors, antioxidants, and growth factors for the prevention or treatment of radiation lesions in general. However, at present, there is no standard procedure for the treatment of radiation-induced normal tissue lesions. Stem cells and their role in tissue regeneration have been known to biologists, in particular to radiobiologists, for many years. It was only recently that the potential of stem cells was studied in the treatment of radiation lesions. Stem cells, immediately after their successful isolation from a variety of animal and human tissues, demonstrated their likely application in the treatment of various diseases. This paper describes the types and origin of stem cells, their characteristics, current research, and reviews their potential in the treatment and regeneration of radiation induced normal tissue lesions. Adult stem cells, among those mesenchymal stem cells (MSCs), are the most extensively studied of stem cells. This review focuses on the effects of MSCs in the treatment of radiation lesions.

Long noncoding RNA repressor of adipogenesis negatively regulates the adipogenic differentiation of mesenchymal stem cells through the hnRNP A1-PTX3-ERK axis

BACKGROUND

Mesenchymal stem cells (MSCs) are pluripotent stem cells that can differentiate via osteogenesis and adipogenesis. The mechanism underlying MSC lineage commitment still remains incompletely elucidated. Understanding the regulatory mechanism of MSC differentiation will help researchers induce MSCs toward specific lineages for clinical use. In this research, we intended to figure out the long noncoding RNA (lncRNA) that plays a central role in MSC fate determination and explore its application value in tissue engineering.

METHODS

The expression pattern of lncRNAs during MSC osteogenesis/adipogenesis was detected by microarray and qRT-PCR. Lentivirus and siRNAs were constructed to regulate the expression of lncRNA repressor of adipogenesis (ROA). MSC osteogenesis/adipogenesis was evaluated by western blot and alizarin red/oil red staining. An adipokine array was used to select the paracrine/autocrine factor PTX3, followed by RNA interference or recombinant human protein stimulation to confirm its function. The activation of signaling pathways was also detected by western blot, and a small molecule inhibitor, SCH772984, was used to inhibit the activation of the ERK pathway. The interaction between ROA and hnRNP A1 was detected by RNA pull-down and RIP assays. Luciferase reporter and chromatin immunoprecipitation assays were used to confirm the binding of hnRNP A1 to the PTX3 promotor. Additionally, an in vivo adipogenesis experiment was conducted to evaluate the regulatory value of ROA in tissue engineering.

RESULTS

In this study, we demonstrated that MSC adipogenesis is regulated by lncRNA ROA both in vitro and in vivo. Mechanistically, ROA inhibits MSC adipogenesis by downregulating the expression of the key autocrine/paracrine factor PTX3 and the downstream ERK pathway. This downregulation was achieved through transcription inhibition by impeding hnRNP A1 from binding to the promoter of PTX3.

CONCLUSIONS

ROA negatively regulates MSC adipogenesis through the hnRNP A1-PTX3-ERK axis. ROA may be an effective target for modulating MSCs in tissue engineering.

Treatment of Grade 3 and 4 Osteoarthritis with Intraoperatively Separated Adipose Tissue-Derived Stromal Vascular Fraction: A Comparative Case Series

Osteoarthritis (OA) is the most common form of arthritis of the joints. The stromal vascular fraction (SVF) is a regenerative cell population that can be isolated from adipose tissue. It is the immunomodulatory properties of the stromal vascular fraction that make it a promising candidate for the regenerative treatment of OA. Patients with grade 3 and 4 osteoarthritis were treated with the stromal vascular fraction with and without platelet-rich plasma (PRP) and followed up on their Knee Injury and Osteoarthritis Outcome Score (KOOS) score for 12 months, with MRI and subjective evaluation of the procedure. Magnetic resonance imaging (MRI) revealed a widening of the joint space, a restructuring of the cartilage, and an alleviation of effusions in the treated joints. In three of the four treatment groups, a substantial improvement of the KOOS scores was documented at the 12-month follow-up time point. According to the subjective evaluation, 67% of the patients were satisfied or very satisfied with the procedure and would recommend it to others. No serious adverse events or unwanted side effects related to the SVF treatment were observed or reported. Prior to an invasive artificial joint replacement, the treatment of arthritic knee joints with the intraarticular injection of autologous adipose tissue-derived SVF should be considered a regenerative treatment option.

Adipose Tissue-Derived Stem Cells Retain Their Adipocyte Differentiation Potential in Three-Dimensional Hydrogels and Bioreactors †

Osteoarthritis (OA) is a common joint disorder with a significant economic and healthcare impact. The knee joint is composed of cartilage and the adjoining bone, a synovial capsule, the infrapatellar fat pad (IPFP), and other connective tissues such as tendons and ligaments. Adipose tissue has recently been highlighted as a major contributor to OA through strong inflammation mediating effects. In this study, methacrylated gelatin (GelMA) constructs seeded with adipose tissue-derived mesenchymal stem cells (ASCs) and cultured in a 3D printed bioreactor were investigated for use in microphysiological systems to model adipose tissue in the knee joint. Four patient-derived ASC populations were seeded at a density of 20 million cells/mL in GelMA. Live/Dead and boron-dipyrromethene/4′,6-diamidino-2-phenylindole (BODIPY/DAPI) staining of cells within the constructs demonstrated robust cell viability after 28 days in a growth (control) medium, and robust cell viability and lipid accumulation in adipogenic differentiation medium. qPCR gene expression analysis and protein analysis demonstrated an upregulated expression of key adipogenesis-associated genes. Overall, these data indicate that ASCs retain their adipogenic potential when seeded within GelMA hydrogels and cultured within perfusion bioreactors, and thus can be used in a 3D organ-on-a-chip system to study the role of the IPFP in the pathobiology of the knee OA.

The Long Pentraxin PTX3 in Bone Homeostasis and Pathology

The innate immune system is equipped with a number of germ-line encoded soluble pattern recognition molecules (PRMs) that collectively mediate the humoral host response to infection and damage in cooperation with cells and tissues of the immune and non-immune compartments. Despite the impressive diversity in structure, source, and regulation across PRMs, these all share remarkably similar functions inasmuch as they recognize microbes and damaged tissues, activate complement, exert opsono-phagocytic activities, and regulate inflammation. The long pentraxin 3 (PTX3) is a prototypic soluble PRM. Long known as a major player in innate immunity, inflammation and matrix remodeling, only recently has PTX3 emerged as a mediator of bone homeostasis in rodents and humans. Ptx3-targeted mice exhibit reduced trabecular volume during bone development, and impaired callus mineralization following experimental fracture. The murine gene is expressed in vivo by non-hematopoietic periosteal cells in the early phases of fracture healing, and in vitro by maturing osteoblasts. Human osteoblasts do express the PTX3 protein, whose levels positively correlate with bone density in vivo and osteoblast proliferation and maturation in vitro, thus pointing to a role in bone deposition. Contrasting evidence, however, suggest osteoclastogenesis-promoting effects of PTX3, where its expression has been associated with periodontitis, arthritis, and bone metastasis, conditions hallmarked by inflammation and bone resorption. Here, we review past and recent literature on the functions exerted by this long pentraxin in bone biology, with major emphasis on physiological skeletal remodeling, fracture healing, and chronic diseases of the bone.

Proteomic Identification and Time-Course Monitoring of Secreted Proteins During Expansion of Human Mesenchymal Stem/Stromal in Stirred-Tank Bioreactor

The therapeutic potential of mesenchymal stem/stromal cells (MSC) is widely recognized for the treatment of several diseases, including acute graft-vs.-host disease (GVHD), hematological malignancies, cardiovascular, bone, and cartilage diseases. More recently, this therapeutic efficacy has been attributed to the bioactive molecules that these cells secrete (secretome), now being referred as medicinal signaling cells. This fact raises the opportunity of therapeutically using MSC-derived soluble factors rather than cells themselves, enabling their translation into the clinic. Indeed, many clinical trials are now studying the effects of MSC-secretome in the context of cell-free therapy. MSC secretome profile varies between donors, source, and culture conditions, making their therapeutic use very challenging. Therefore, identifying these soluble proteins and evaluating their production in a reproducible and scalable manner is even more relevant. In this work, we analyzed the global profile of proteins secreted by umbilical cord matrix (UCM) derived-MSC in static conditions by using mass spectrometry, enabling the identification of thousands of proteins. Afterwards, relevant proteins were chosen and monitored in the supernatant of a fully-controllable, closed and scalable system (bioreactor) by using multiple reaction monitoring (MRM) mass spectrometric technique in a time-dependent manner. The results showed that the majority of interesting proteins were enriched through time in culture, with the last day of culture being the ideal time for supernatant collection. The use of this regenerative "soup," which is frequently discarded, could represent a step toward a safe, robust and reproducible cell-free product to be used in the medical therapeutic field. The future use of chemically defined culture-media will certainly facilitate secretome production according to Good Manufacturing Practice (GMP) standards.

Alternative splicing events during adipogenesis from hMSCs

Adipogenesis, the developmental process of progenitor-cell differentiating into adipocytes, leads to fat metabolic disorders. Alternative splicing (AS), a ubiquitous regulatory mechanism of gene expression, allows the generation of more than one unique messenger RNA (mRNA) species from a single gene. Till now, alternative splicing events during adipogenesis from human mesenchymal stem cells (hMSCs) are not yet fully elucidated. We performed RNA-Seq coupled with bioinformatics analysis to identify the differentially expressed AS genes and events during adipogenesis from hMSCs. A global survey separately identified 1262, 1181, 1167, and 1227 ASE involved in the most common types of AS including cassette exon, alt3, and alt5, especially with cassette exon the most prevalent, at 7, 14, 21, and 28 days during adipogenesis. Interestingly, 122 differentially expressed ASE referred to 118 genes, and the three genes including ACTN1 (alt3 and cassette), LRP1 (alt3 and alt5), and LTBP4 (cassette, cassette_multi, and unknown), appeared in multiple AS types of ASE during adipogenesis. Except for all the identified ASE of LRP1 occurred in the extracellular topological domain, alt3 (84) in transmembrane domain significantly differentially expressed was the potential key event during adipogenesis. Overall, we have, for the first time, conducted the global transcriptional profiling during adipogenesis of hMSCs to identify differentially expressed ASE and ASE-related genes. This finding would provide extensive ASE as the regulator of adipogenesis and the potential targets for future molecular research into adipogenesis-related metabolic disorders.

Adipose-derived Stem Cells Attenuates Diabetic Osteoarthritis via Inhibition of Glycation-mediated Inflammatory Cascade

Diabetes mellitus (DM) is well-known to exert complications such as retinopathy, cardiomyopathy and neuropathy. However, in recent years, an elevated osteoarthritis (OA) complaints among diabetics have been observed, portending the risk of diabetic OA. Since formation of advanced glycation end products (AGE) is believed to be the etiology of various diseases under hyperglycemic conditions, we firstly established that streptozotocin-induced DM could potentiate the development of OA in C57BL/6J mouse model, and further explored the intra-articularly administered adipose-derived stem cell (ADSC) therapy focusing on underlying AGE-associated mechanism. Our results demonstrated that hyperglycemic mice exhibited OA-like structural impairments including a proteoglycan loss and articular cartilage fibrillations in knee joint. Highly expressed levels of carboxymethyl lysine (CML), an AGE and their receptors (RAGE), which are hallmarks of hyperglycemic microenvironment were manifested. The elevated oxidative stress in diabetic OA knee-joint was revealed through increased levels of malondialdehyde (MDA). Further, oxidative stress-activated nuclear factor kappa B (NF-κB), the marker of proinflammatory signalling pathway was also accrued; and levels of matrix metalloproteinase-1 and 13 were upregulated. However, ADSC treatment attenuated all OA-like changes by 4 weeks, and dampened levels of CML, RAGE, MDA, NF-κB, MMP-1 and 13. These results suggest that during repair and regeneration, ADSCs inhibited glycation-mediated inflammatory cascade and rejuvenated cartilaginous tissue, thereby promoting knee-joint integrity in diabetic milieu.

Rescue of degenerating neurons and cells by stem cell released molecules: using a physiological renormalization strategy

Evidence suggests that adult stem cell types and progenitor cells act collectively in a given tissue to maintain and heal organs, such as muscle, through a release of a multitude of molecules packaged into exosomes from the different cell types. Using this principle for the development of bioinspired therapeutics that induces homeostatic renormalization, here we show that the collection of molecules released from four cell types, including mesenchymal stem cells, fibroblast, neural stem cells, and astrocytes, rescues degenerating neurons and cells. Specifically, oxidative stress induced in a human recombinant TDP-43- or FUS-tGFP U2OS cell line by exposure to sodium arsenite was shown to be significantly reduced by our collection of molecules using in vitro imaging of FUS and TDP-43 stress granules. Furthermore, we also show that the collective secretome rescues cortical neurons from glutamate toxicity as evidenced by increased neurite outgrowth, reduced LDH release, and reduced caspase 3/7 activity. These data are the first in a series supporting the development of stem cell-based exosome systems therapeutics that uses a physiological renormalization strategy to treat neurodegenerative diseases.

Loss of Nmp4 optimizes osteogenic metabolism and secretion to enhance bone quality

A goal of osteoporosis therapy is to restore lost bone with structurally sound tissue. Mice lacking the transcription factor nuclear matrix protein 4 (Nmp4, Zfp384, Ciz, ZNF384) respond to several classes of osteoporosis drugs with enhanced bone formation compared with wild-type (WT) animals. Nmp4-/- mesenchymal stem/progenitor cells (MSPCs) exhibit an accelerated and enhanced mineralization during osteoblast differentiation. To address the mechanisms underlying this hyperanabolic phenotype, we carried out RNA-sequencing and molecular and cellular analyses of WT and Nmp4-/- MSPCs during osteogenesis to define pathways and mechanisms associated with elevated matrix production. We determined that Nmp4 has a broad impact on the transcriptome during osteogenic differentiation, contributing to the expression of over 5,000 genes. Phenotypic anchoring of transcriptional data was performed for the hypothesis-testing arm through analysis of cell metabolism, protein synthesis and secretion, and bone material properties. Mechanistic studies confirmed that Nmp4-/- MSPCs exhibited an enhanced capacity for glycolytic conversion: a key step in bone anabolism. Nmp4-/- cells showed elevated collagen translation and secretion. The expression of matrix genes that contribute to bone material-level mechanical properties was elevated in Nmp4-/- cells, an observation that was supported by biomechanical testing of bone samples from Nmp4-/- and WT mice. We conclude that loss of Nmp4 increases the magnitude of glycolysis upon the metabolic switch, which fuels the conversion of the osteoblast into a super-secretor of matrix resulting in more bone with improvements in intrinsic quality.

Secretome of Mesenchymal Stem Cells and Its Potential Protective Effects on Brain Pathologies

Previous studies have indicated that mesenchymal stem cells (MSCs) have a fundamental role in the repair and regeneration of damaged tissues. There is strong evidence showing that much of the beneficial effects of these cells are due to the secretion of bioactive molecules-besides microRNAs, hormones, and neurotrophins-with anti-inflammatory, immunoregulatory, angiogenic, and trophic effects. These factors have been reported by many studies to possess protective effects on the nervous tissue. Although the beneficial effects of the secretory factors of MSCs have been suggested for various neurological diseases, their actions on astrocytic cells are not well understood. Hence, it is important to recognize the specific effects of MSCs derived from adipose tissue, in addition to the differences presented by the secretome, depending on the source and methods of analysis. In this paper, the different sources of MSCs and their main characteristics are described, as well as the most significant advances in regeneration and protection provided by the secretome of MSCs. Also, we discuss the possible neuroprotective mechanisms of action of the MSC-derived biomolecules, with special emphasis on the effect of MSCs derived from adipose tissue and their impact on glial cells and brain pathologies.

Abdominal Obesity is Associated With Lower Bone Mineral Density in Non-Weight-Bearing Site in Korean Men

This research aimed to investigate the relationship between abdominal obesity and lower bone mineral density (BMD) at non-weight-bearing site in Korean men using data from the Korea National Health and Nutrition Examination Survey, which is a nationwide cross-sectional survey. The study population (n = 5,941) was selected from the 2009–2010 survey. Abdominal obesity in men was defined as waist circumference ⩾ 90 cm. Lower BMD state was defined as having T-score of −2.5 or below. To investigate the association, multiple logistic regression analysis was performed. Abdominal obesity was highly associated with lower non-weight-bearing site (lumbar spine [LS]) BMD after adjustment (odds ratio [OR] 1.61, 95% CI [1.06, 2.44], p = .026). Also, abdominal obesity was a risk factor for lower LS BMD, especially in age groups of those in their 20s and those over 60s (OR 5.53, 95% CI [1.27, 24.07], p = .023 for 20s; OR 2.19, 95% CI [1.19, 4.02], p = .011 for 60 years or older). Abdominal obesity in Korean men is associated with lower BMD at non-weight-bearing site (LS), especially in younger and older age groups. Further research might be recommended to prove the mechanism or causality.

Multifaced Roles of the Urokinase System in the Regulation of Stem Cell Niches

Proliferation, subsequent migration to the damaged area, differentiation into appropriate cell types, and/or secretion of biologically active molecules and extracellular vesicles are important processes that underlie the involvement of stem/progenitor cells in the repair and regeneration of tissues and organs. All these functions are regulated through the interaction between stem cells and the microenvironment in the tissue cell niches that control these processes through direct cell-cell interactions, production of the extracellular matrix, release of extracellular vesicles, and secretion of growth factors, cytokines, chemokines, and proteases. One of the most important proteolytic systems involved in the regulation of cell migration and proliferation is the urokinase system represented by the urokinase plasminogen activator (uPA, urokinase), its receptor (uPAR), and inhibitors. This review addresses the issues of urokinase system involvement in the regulation of stem cell niches in various tissues and analyzes the possible effects of this system on the signaling pathways responsible for the proliferation, programmed cell death, phenotype modulation, and migration properties of stem cells.

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.

The role of the thioredoxin/thioredoxin reductase system in the metabolic syndrome: towards a possible prognostic marker?

Mammalian thioredoxin reductase (TrxR) is a selenoprotein with three existing isoenzymes (TrxR1, TrxR2, and TrxR3), which is found primarily intracellularly but also in extracellular fluids. The main substrate thioredoxin (Trx) is similarly found (as Trx1 and Trx2) in various intracellular compartments, in blood plasma, and is the cell's major disulfide reductase. Thioredoxin reductase is necessary as a NADPH-dependent reducing agent in biochemical reactions involving Trx. Genetic and environmental factors like selenium status influence the activity of TrxR. Research shows that the Trx/TrxR system plays a significant role in the physiology of the adipose tissue, in carbohydrate metabolism, insulin production and sensitivity, blood pressure regulation, inflammation, chemotactic activity of macrophages, and atherogenesis. Based on recent research, it has been reported that the modulation of the Trx/TrxR system may be considered as a new target in the management of the metabolic syndrome, insulin resistance, and type 2 diabetes, as well as in the treatment of hypertension and atherosclerosis. In this review evidence about a possible role of this system as a marker of the metabolic syndrome is reported.

Secretome analysis of breast cancer-associated adipose tissue to identify paracrine regulators of breast cancer growth

Adipose tissue secretes a plethora of adipokines as evidenced by characterization of subcutaneous and visceral adipose tissue secretomes. However, adipose tissue composition and secretion pattern is depot and disease dependent, influencing the adipose tissue secretome. We investigated the secretome of cancer-associated adipose tissue (CAAT) explants from breast cancer patients and explored its role in breast cancer proliferation. CAAT proteins were identified by LC-MS/MS and human protein antibody arrays and stimulated proliferation of three breast cancer cell lines. Kinomics and transcriptomics of MCF-7 breast cancer cells treated with the secretome of CAAT revealed activation of Akt-, ERK- and JNK-pathways and differential expression of activator protein 1 (AP-1) and cAMP responsive element-binding protein (CREB) target genes. The cyclin-dependent kinase (CDK)4/6-inhibitor palbociclib significantly abrogated CAAT-enhanced breast cancer cell proliferation. Our work characterizes the specific breast CAAT protein secretome and reveals its pro-proliferative potency in breast cancer.

Secretome analysis of in vitro aged human mesenchymal stem cells reveals IGFBP7 as a putative factor for promoting osteogenesis

Aging is a complex biological process, which involves multiple mechanisms with different levels of regulation. Senescent cells are known to secrete senescence-associated proteins, which exert negative influences on surrounding cells. Mesenchymal stem cells (MSCs), the common progenitors for bone, cartilage and adipose tissue (which are especially affected tissues in aging), are known to secrete a broad spectrum of biologically active proteins with both paracrine and autocrine functions in many biological processes. In this report, we have studied the secreted factors (secretome) from human MSCs (hMSCs) and hMSCs-derived adipocytes which were induced to accumulate prelamin A, the immature form of the nuclear lamina protein called Lamin A, known to induce premature aging syndromes in humans and in murine models. Proteomic analysis from two different techniques, antibody arrays and LS-MS, showed that prelamin A accumulation in hMSCs promotes the differential secretion of factors previously identified as secreted by hMSCs undergoing osteogenesis. Moreover, this secretome was able to modulate osteogenesis of normal hMSCs in vitro. Finally, we found that one of the overexpressed secreted factors of this human aging in vitro stem cell model, IGFBP-7, is an osteogenic factor, essential for the viability of hMSCs during osteogenesis.

The Long Pentraxin 3 Plays a Role in Bone Turnover and Repair

Pentraxin 3 (PTX3) is an inflammatory mediator acting as a fluid-phase pattern recognition molecule and playing an essential role in innate immunity and matrix remodeling. Inflammatory mediators also contribute to skeletal homeostasis, operating at multiple levels in physiological and pathological conditions. This study was designed to investigate the role of PTX3 in physiological skeletal remodeling and bone healing. Micro-computed tomography (μCT) and bone histomorphometry of distal femur showed that PTX3 gene-targeted female and male mice (ptx3^−/−) had lower trabecular bone volume than their wild-type (ptx3^+/+) littermates (BV/TV by μCT: 3.50 ± 1.31 vs 6.09 ± 1.17 for females, p < 0.0001; BV/TV 9.06 ± 1.89 vs 10.47 ± 1.97 for males, p = 0.0435). In addition, μCT revealed lower trabecular bone volume in second lumbar vertebra of ptx3^−/− mice. PTX3 was increasingly expressed during osteoblast maturation in vitro and was able to reverse the negative effect of fibroblast growth factor 2 (FGF2) on osteoblast differentiation. This effect was specific for the N-terminal domain of PTX3 that contains the FGF2-binding site. By using the closed transversal tibial fracture model, we found that ptx3^−/− female mice formed significantly less mineralized callus during the anabolic phase following fracture injury compared to ptx3^+/+ mice (BV/TV 17.05 ± 4.59 vs 20.47 ± 3.32, p = 0.0195). Non-hematopoietic periosteal cells highly upregulated PTX3 expression during the initial phase of fracture healing, particularly CD51⁺ and αSma⁺ osteoprogenitor subsets, and callus tissue exhibited concomitant expression of PTX3 and FGF2 around the fracture site. Thus, PTX3 supports maintenance of the bone mass possibly by inhibiting FGF2 and its negative impact on bone formation. Moreover, PTX3 enables timely occurring sequence of callus mineralization after bone fracture injury. These results indicate that PTX3 plays an important role in bone homeostasis and in proper matrix mineralization during fracture repair, a reflection of the function of this molecule in tissue homeostasis and repair.

Amyotrophic lateral sclerosis as a protein level, non-genomic disease: Therapy with S2RM exosome released molecules

Amyotrophic lateral sclerosis (ALS) is a rapidly progressing neurodegenerative disease that leads to death. No effective treatments are currently available. Based on data from epidemiological, etiological, laboratory, and clinical studies, I offer a new way of thinking about ALS and its treatment. This paper describes a host of extrinsic factors, including the exposome, that disrupt the extracellular matrix and protein function such that a spreading, prion-like disease leads to neurodegeneration in the motor tracts. A treatment regimen is described using the stem cell released molecules from a number of types of adult stem cells to provide tissue dependent molecules that restore homeostasis, including proteostasis, in the ALS patient. Because stem cells themselves as a therapeutic are cumbersome and expensive, and when implanted in a host cause aging of the host tissue and often fail to engraft or remain viable, only the S2RM molecules are used. Rebuilding of the extracellular matrix and repair of the dysfunctional proteins in the ALS patient ensues.

The stem cell regulator PEDF is dispensable for maintenance and function of hematopoietic stem cells

Pigment epithelium derived factor (PEDF), a ubiquitously expressed 50 kDa secreted glycoprotein, was recently discovered to regulate self-renewal of neural stem cells and have a supportive effect on human embryonic stem cell growth. Here, we analyzed expression of PEDF in the murine hematopoietic stem cell (HSC) compartments and found that PEDF is highly expressed in primary long-term HSCs. Therefore, we characterized the hematopoietic system in a knockout mouse model for PEDF and using this model we surprisingly found that PEDF is dispensable for HSC regulation. PEDF knockout mice exhibit normal hematopoiesis in steady state conditions and the absence of PEDF lead to normal regeneration capacity in a serial competitive transplantation setting. Additionally, PEDF-deficient cells exhibit unaltered lineage distribution upon serial transplantations. When human cord blood stem and progenitor cells were cultured in media supplemented with recombinant PEDF they did not show changes in growth potential. Taken together, we report that PEDF is not a critical regulatory factor for HSC function during regeneration in vivo or growth of human stem/progenitor cells in vitro.

Insights into cell-free therapeutic approach: Role of stem cell "soup-ernatant"

Current advances in medicine have revolutionized the field of regenerative medicine dramatically with newly evolved therapies for repair or replacement of degenerating or injured tissues. Stem cells (SCs) can be harvested from different sources for clinical therapeutics, which include fetal tissues, umbilical cord blood, embryos, and adult tissues. SCs can be isolated and differentiated into desired lineages for tissue regeneration and cell replacement therapy. However, several loopholes need to be addressed properly before this can be extended for large-scale therapeutic application. These include a careful approach for patient safety during SC treatments and tolerance of recipients. SC treatments are associated with a number of risk factors and require successful integration and survival of transplanted cells in the desired microenvironment with concurrent tissue regeneration. Recent studies have focused on developing alternatives that can replace the cell-based therapy using paracrine factors. The development of stem "cell free" therapies can be devoted mainly to the use of soluble factors (secretome), extracellular vesicles, and mitochondrial transfer. The present review emphasizes on the paradigms related to the use of SC-based therapeutics and the potential applications of a cell-free approach as an alternative to cell-based therapy in the area of regenerative medicine.

Impairment of the activin A autocrine loop by lopinavir reduces self-renewal of distinct human adipose progenitors

Maintenance of the adipose tissue requires a proper balance between self-renewal and differentiation of adipose progenitors (AP). Any deregulation leads either to fat overexpansion and obesity or fat loss and consequent lipodystrophies. Depending on the fat pad location, APs and adipocytes are heterogeneous. However, information on the pharmacological sensitivity of distinct APs to drugs known to alter the function of adipose tissue, especially HIV protease inhibitors (PIs) is scant. Here we show that PIs decreased proliferation and clonal expansion of APs, modifying their self-renewal potential. Lopinavir was the most potent PI tested. Decrease in self-renewal was accompanied by a reduced expression of the immediate early response gene IER3, a gene associated with tissue expansion. It was more pronounced in chin-derived APs than in knee-derived APs. Furthermore, lopinavir lowered the activin A–induced ERK1/2 phosphorylation. Expressions of the transcription factor EGR1 and its targets, including INHBA were subsequently altered. Therefore, activin A secretion was reduced leading to a dramatic impairment of APs self-renewal sustained by the activin A autocrine loop. All together, these observations highlight the activin A autocrine loop as a crucial effector to maintain APs self-renewal. Targeting this pathway by HIV-PIs may participate in the induction of unwanted side effects.

Intraperitoneal adoptive transfer of mesenchymal stem cells enhances recovery from acid aspiration acute lung injury in mice

Background

Mesenchymal stem cells (MSCs) might act as fine-tuners of inflammation during acute lung injury. We assessed the effects of adoptive transfer of MSCs in acid aspiration acute lung injury and explored the role of long pentraxin PTX3.

Methods

We conducted a prospective experimental interventional study on wild-type (WT) and PTX3-deficient (PTX3^−/−) mice. Acute lung injury was induced in WT and PTX3^−/− mice by instillation of hydrochloric acid into the right bronchus. One hour later, animals received intraperitoneal sterile phosphate-buffered saline (PBS), WT-MSCs (1 × 10⁶) or PTX3^−/−-MSCs (1 × 10⁶). Twenty-four hours after injury, we measured the effects of treatments on arterial blood gases, wet/dry lung weight (W/D), CT scan analysis of lung collapse, neutrophils, TNFα and CXCL1 in bronchoalveolar lavage, and plasma PTX3. d-dimer was assayed in 1 week and OH-proline in 2 weeks to track the fibrotic evolution.

Results

In 24 h, in comparison to PBS, WT-MSCs improved oxygenation and reduced W/D and alveolar collapse. These effects were associated with decreased concentrations of alveolar neutrophils and cytokines. WT-MSCs increased d-dimer concentration and decreased OH-proline levels, too.

Treatment with PTX3^−/−-MSCs ameliorated oxygenation, W/D, and alveolar TNFα, though to a lesser extent than WT-MSCs. PTX3^−/−-MSCs did not improve lung collapse, neutrophil count, CXCL1, d-dimer, and OH-proline concentrations. The protective effects of WT-MSCs were dampened by lack of endogenous PTX3, too.

Conclusions

In acid aspiration acute lung injury, MSCs improve pulmonary function and limit fibrosis by fine-tuning inflammation. The role of PTX3 in determining MSCs’ effects might merit further scrutiny.

Electronic supplementary material

The online version of this article (doi:10.1186/s40635-017-0126-5) contains supplementary material, which is available to authorized users.

Geranylgeranyl pyrophosphate performs as an endogenous regulator of adipocyte function via suppressing the LXR pathway

Isoprenoids such as geranylgeranyl pyrophosphate (GGPP) influence various biological processes. Here we show that GGPP inhibits adipocyte differentiation via the liver X receptors (LXRs) pathway. Intracellular GGPP levels and GGPP synthase (Ggps) mRNA expression increases during adipocyte differentiation. Ggps expression also increases in white adipose tissue of obese mice. GGPP addition reduces the expression of adipogenic marker genes such as adipocyte fatty acid binding protein, peroxisome proliferator-activated receptor γ, and insulin-stimulated glucose uptake. Similarly, over-expressing Ggps inhibits adipocyte differentiation. In contrast, Ggps knockdown promotes adipocyte differentiation. Inhibition of adipocyte differentiation by GGPP was partially reduced by LXR agonist T0901317. Furthermore, Ggps knockdown up-regulates LXR target genes during adipocyte differentiation. These results suggest that GGPP may act as an endogenous regulator of adipocyte differentiation and maturation through a mechanism partially dependent on the LXR pathway.

Human platelet lysate supplementation of mesenchymal stromal cell delivery: issues of xenogenicity and species variability

Immunogenicity of fetal bovine serum (FBS) poses a problem for its use in the propagation of autologous mesenchymal stromal cells (MSCs) for cell therapy. Human platelet lysate (hPL), an enriched growth factor solution containing mitogenic and angiogenic cues, has potential utility in replacing FBS for human MSC (hMSC) delivery strategies. Despite its potentiation of hMSC number in vitro, little is known concerning its capacity to supplement implanted hMSC-seeded constructs and promote tissue regeneration in vivo. In this study, we tested the effects of incorporating hPL in cell-seeded constructs implanted subcutaneously into immunocompromised rats, investigated in vitro interactions between hPL and rat MSCs (rMSCs) and determined interspecies variability in the PL product [hPL vs rat PL (rPL)] and its effect on cultured MSCs (hPL/hMSCs vs rPL/rMSCs). The overarching aim was to determine the utility of hPL to foster MSC survival in preclinical rodent models. Exposure to hPL-supplemented media resulted in rMSC death, by a process attributable to heat-labile proteins, but not membrane attack complex formation. In the in vitro syngeneic model, the rodent product proved fundamentally distinct from the human product, with rPL having substantially lower growth factor content than hPL. Moreover, contrary to the positive effects of hPL on hMSC expansion, rPL did not reduce rMSC doubling time for the serum concentrations examined. When tested in vivo, hPL did not improve cell survival within hydrogel constructs through 2 weeks postimplantation. In summary, this study highlights the many facets of xenogenicity and interspecies variability that must be considered in the preclinical evaluation of hPL. Copyright © 2016 John Wiley & Sons, Ltd.

Mesenchymal Stromal Cell-Derived PTX3 Promotes Wound Healing via Fibrin Remodeling

Although mesenchymal stromal cells (MSCs) can promote wound healing in different clinical settings, the underlying mechanism of MSC-mediated tissue repair has yet to be determined. Because a nonredundant role of pentraxin 3 (PTX3) in tissue repair and remodeling has been recently described, here we sought to determine whether MSC-derived PTX3 might play a role in wound healing. Using a murine model of skin repair, we found that Ptx3-deficient (Ptx3(-/-)) MSCs delayed wound closure and reduced granulation tissue formation compared with wt MSCs. At day 2, confocal microscopy revealed a dramatic reduction in green fluorescent protein (GFP)-expressing Ptx3(-/-) MSCs recruited to the wound, where they appeared to be not only poorly organized in bundles but also scattered in the extracellular matrix. These findings were further confirmed by quantitative biochemical analysis of GFP content in wound extracts. Furthermore, Ptx3(-/-) MSC-treated skins displayed increased levels of fibrin and lower levels of D-dimer, suggesting delayed fibrin-rich matrix remodeling compared with control skins. Consistently, both pericellular fibrinolysis and migration through fibrin were found to be severely affected in Ptx3(-/-) MSCs. Overall, our findings identify an essential role of MSC-derived PTX3 in wound repair underscoring the beneficial potential of MSC-based therapy in the management of intractable wounds.

Biomolecular features of inflammation in obese rheumatoid arthritis patients: management considerations

Adipose tissue is an active organ playing a role not only in metabolism but also in immune and inflammatory processes, releasing several pro-inflammatory mediators. This can explain the possible association between obesity and rheumatoid arthritis (RA) and its role in the progression of the disease. Adipose and synovial tissues share common histological features of local inflammation in terms of activation of target tissues infiltrating cells (i.e. myeloid cells). Among the so-called adipocytokines, PEDF and Chemerin orchestrate the cellular cross-talk between adipose and myeloid cells, being possible biomarkers to monitor the effect of weight loss or the decrease of adipose tissue in patients with RA. Moreover, dietary intervention has been demonstrated to reduce Chemerin as well as IL-6 and MCP-1 expression. Finally, epigenetic regulators such as micro-RNAs (i.e. miR-155) are key regulators of myeloid cells activation in RA and obesity as well as in adipocytes. In this review, we will summarize the biological link between obesity/overweight state and RA focusing on pathophysiological mechanisms, consequences and management considerations.

In vivo immunomodulatory effects of adipose-derived mesenchymal stem cells conditioned medium in experimental autoimmune encephalomyelitis

Mesenchymal stem cells (MSCs) are well known to possess neuroprotective and immunomodulatory effects, due to cell-to-cell interaction and their soluble factors. We conducted a comparative analysis of the immunomodulatory properties of adipose tissue mesenchymal stem cells (AT-MSCs) and their conditioned media (CM), derived from C57/BL6 mice, for mitigating the adverse clinical course of experimental autoimmune encephalomyelitis (EAE). We measure IL4, IL17 and IFNɣ production of supernatant from spleen cells. We analyzed brain cell infiltration, splenocyte proliferation and evaluated the percentage of CD4+CD25+FOXP3+splenic cell population in all EAE C57/BL6 mice. AT-MSCs and its conditioned medium induced CD4+CD25+FOXP3+regulatory T cells after in vitro co-culture with naïve T cells. There is no significant difference in the clinical scores and body weight of EAE mice treated with AT-MSCs and CM. The reduction in proliferative responses and brain cell infiltration was more pronounced in mice injected with CM than other groups. It is found that the percentage of splenic CD4+CD25+FOXP3+ population as well as the level of IL4 production in mice administrated with AT-MSCs is increased compared to other animals. Our results suggest that AT-MSCs-derived CM is promising in stem cell therapy, due to their neuroprotective and immunomudulatory properties.

The Effects of Endocrine Disruptors on Adipogenesis and Osteogenesis in Mesenchymal Stem Cells: A Review

Endocrine-disrupting chemicals (EDCs) are prevalent in the environment, and epidemiologic studies have suggested that human exposure is linked to chronic diseases, such as obesity and diabetes. In vitro experiments have further demonstrated that EDCs promote changes in mesenchymal stem cells (MSCs), leading to increases in adipogenic differentiation, decreases in osteogenic differentiation, activation of pro-inflammatory cytokines, increases in oxidative stress, and epigenetic changes. Studies have also shown alteration in trophic factor production, differentiation ability, and immunomodulatory capacity of MSCs, which have significant implications to the current studies exploring MSCs for tissue engineering and regenerative medicine applications and the treatment of inflammatory conditions. Thus, the consideration of the effects of EDCs on MSCs is vital when determining potential therapeutic uses of MSCs, as increased exposure to EDCs may cause MSCs to be less effective therapeutically. This review focuses on the adipogenic and osteogenic differentiation effects of EDCs as these are most relevant to the therapeutic uses of MSCs in tissue engineering, regenerative medicine, and inflammatory conditions. This review will highlight the effects of EDCs, including organophosphates, plasticizers, industrial surfactants, coolants, and lubricants, on MSC biology.

The conditioned medium from osteo-differentiating human mesenchymal stem cells affects the viability of triple negative MDA-MB231 breast cancer cells

This study aimed to investigate the effect of conditioned media (CM) from osteo-differentiating and adipo-differentiating human mesenchymal stem cells (MSCs) isolated from lipoaspirates of healthy female donors on the viability of triple-negative breast cancer cells MDA-MB231. The CM of undifferentiated and differentiating MSCs were collected after 7, 14, 21 and 28 days of culture. The effects of MSC CM on cell proliferation were assessed using an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay after 24 h. The effects of osteo-differentiating cell CM on apoptotic promotion, cell cycle impairment, mitochondrial transmembrane potential dissipation, production of reactive oxygen species and autophagosome accumulation were analysed by flow cytometry and Western blot. MTT assay showed that only CM collected from osteo-induced cells at day 28 (d28O-CM) reduced tumour cell viability. Treatment with d28O-CM restrained cell cycle progression through G2 phase, elicited a caspase-8-driven apoptotic effect already after 5 h of culture, and down-regulated autophagosome accumulation and beclin-1 expression. The finding that factor(s) secreted by osteo-differentiating MSCs shows properties of an apoptotic inducer and autophagy inhibitor on triple-negative breast cancer cells may have an important applicative potential that deserves further investigation.

Role of mesenchymal stem cell-derived fibrinolytic factor in tissue regeneration and cancer progression

Tissue regeneration during wound healing or cancer growth and progression depends on the establishment of a cellular microenvironment. Mesenchymal stem cells (MSC) are part of this cellular microenvironment, where they functionally modulate cell homing, angiogenesis, and immune modulation. MSC recruitment involves detachment of these cells from their niche, and finally MSC migration into their preferred niches; the wounded area, the tumor bed, and the BM, just to name a few. During this recruitment phase, focal proteolysis disrupts the extracellular matrix (ECM) architecture, breaks cell-matrix interactions with receptors, and integrins, and causes the release of bioactive fragments from ECM molecules. MSC produce a broad array of proteases, promoting remodeling of the surrounding ECM through proteolytic mechanisms. The fibrinolytic system, with its main player plasmin, plays a crucial role in cell migration, growth factor bioavailability, and the regulation of other protease systems during inflammation, tissue regeneration, and cancer. Key components of the fibrinolytic cascade, including the urokinase plasminogen activator receptor (uPAR) and plasminogen activator inhibitor-1 (PAI-1), are expressed in MSC. This review will introduce general functional properties of the fibrinolytic system, which go beyond its known function of fibrin clot dissolution (fibrinolysis). We will focus on the role of the fibrinolytic system for MSC biology, summarizing our current understanding of the role of the fibrinolytic system for MSC recruitment and the functional consequences for tissue regeneration and cancer. Aspects of MSC origin, maintenance, and the mechanisms by which these cells contribute to altered protease activity in the microenvironment under normal and pathological conditions will also be discussed.

A polyion complex sensor array for markerless and noninvasive identification of differentiated mesenchymal stem cells from human adipose tissue

Currently available methods for stem cell evaluation require both prior knowledge of specific markers and invasive cell lysis or staining, hampering the development of stem cell products with assured safety and quality. Here, we present a strategy using optical cross-reactive sensor arrays for markerless and noninvasive identification of differentiated stem cell lineages with common laboratory equipment. The sensor array consists of a library of polyion complexes (PICs) between anionic enzymes and synthetic poly(ethylene glycol)-modified polyamines, which can recognize "secretomic signatures" in cell culture supernatants. Due to the reversible nature of PIC formation, the incubation of diluted culture supernatants with PICs caused enzyme release through competitive interactions between the secreted molecules and the PICs, generating unique patterns of recovery in enzyme activity for individual cell types or lineages. Linear discriminant analysis of the patterns allowed not only normal/cancer cell discrimination but also lineage identification of osteogenic and adipogenic differentiation of human mesenchymal stem cells, therefore providing an effective way to characterize cultured cells in the fields of regenerative medicine, tissue engineering and cell biology.

Impacts of Alternative Splicing Events on the Differentiation of Adipocytes

Alternative splicing was found to be a common phenomenon after the advent of whole transcriptome analyses or next generation sequencing. Over 90% of human genes were demonstrated to undergo at least one alternative splicing event. Alternative splicing is an effective mechanism to spatiotemporally expand protein diversity, which influences the cell fate and tissue development. The first focus of this review is to highlight recent studies, which demonstrated effects of alternative splicing on the differentiation of adipocytes. Moreover, use of evolving high-throughput approaches, such as transcriptome analyses (RNA sequencing), to profile adipogenic transcriptomes, is also addressed.

The role of novel and known extracellular matrix and adhesion molecules in the homeostatic and regenerative bone marrow microenvironment

Maintenance of haematopoietic stem cells and differentiation of committed progenitors occurs in highly specialized niches. The interactions of haematopoietic stem and progenitor cells (HSPCs) with cells, growth factors and extracellular matrix (ECM) components of the bone marrow (BM) microenvironment control homeostasis of HSPCs. We only start to understand the complexity of the haematopoietic niche(s) that comprises endosteal, arterial, sinusoidal, mesenchymal and neuronal components. These distinct niches produce a broad range of soluble factors and adhesion molecules that modulate HSPC fate during normal hematopoiesis and BM regeneration. Adhesive interactions between HSPCs and the microenvironment will influence their localization and differentiation potential. In this review we highlight the current understanding of the functional role of ECM- and adhesion (regulating) molecules in the haematopoietic niche during homeostatic and regenerative hematopoiesis. This knowledge may lead to the improvement of current cellular therapies and more efficient development of future cellular products.

ProteINSIDE to Easily Investigate Proteomics Data from Ruminants: Application to Mine Proteome of Adipose and Muscle Tissues in Bovine Foetuses

Genomics experiments are widely acknowledged to produce a huge amount of data to be analysed. The challenge is to extract meaningful biological context for proteins or genes which is currently difficult because of the lack of an integrative workflow that hinders the efficiency and the robustness of data mining performed by biologists working on ruminants. Thus, we designed ProteINSIDE, a free web service (www.proteinside.org) that (I) provides an overview of the biological information stored in public databases or provided by annotations according to the Gene Ontology, (II) predicts proteins that are secreted to search for proteins that mediate signalisation between cells or tissues, and (III) analyses protein-protein interactions to identify proteins contributing to a process or to visualize functional pathways. Using lists of proteins or genes as a unique input, ProteINSIDE is an original all-in-one tool that merges data from these searches to present a fast overview and integrative analysis of genomic and proteomic data from Bovine, Ovine, Caprine, Human, Rat, and Murine species. ProteINSIDE was bench tested with 1000 proteins identifiers from each species by comparison with DAVID, BioMyn, AgBase, PrediSi, and Phobius. Compared to DAVID or BioMyn, identifications and annotations provided by ProteINSIDE were similar from monogastric proteins but more numerous and relevant for ruminants proteins. ProteINSIDE, thanks to SignalP, listed less proteins potentially secreted with a signal peptide than PrediSi and Phobius, in agreement with the low false positive rate of SignalP. In addition ProteINSIDE is the only resource that predicts proteins secreted by cellular processes that do not involve a signal peptide. Lastly, we reported the usefulness of ProteINSIDE to bring new biological hypotheses of research from proteomics data: the biological meaning of the uptake of adiponectin by the foetal muscle and a role for autophagy during ontogenesis of adipose and muscle tissues.

Recent advances in proteomic studies of adipose tissues and adipocytes

Obesity is a chronic disease that is associated with significantly increased levels of risk of a number of metabolic disorders. Despite these enhanced health risks, the worldwide prevalence of obesity has increased dramatically over the past few decades. Obesity is caused by the accumulation of an abnormal amount of body fat in adipose tissue, which is composed mostly of adipocytes. Thus, a deeper understanding of the regulation mechanism of adipose tissue and/or adipocytes can provide a clue for overcoming obesity-related metabolic diseases. In this review, we describe recent advances in the study of adipose tissue and/or adipocytes, focusing on proteomic approaches. In addition, we suggest future research directions for proteomic studies which may lead to novel treatments of obesity and obesity-related diseases.

Nanoscale strategies: treatment for peripheral vascular disease and critical limb ischemia

Peripheral vascular disease (PVD) is one of the most prevalent vascular diseases in the U.S. afflicting an estimated 8 million people. Obstruction of peripheral arteries leads to insufficient nutrients and oxygen supply to extremities, which, if not treated properly, can potentially give rise to a severe condition called critical limb ischemia (CLI). CLI is associated with extremely high morbidities and mortalities. Conventional treatments such as angioplasty, atherectomy, stent implantation and bypass surgery have achieved some success in treating localized macrovascular disease but are limited by their invasiveness. An emerging alternative is the use of growth factor (delivered as genes or proteins) and cell therapy for PVD treatment. By delivering growth factors or cells to the ischemic tissue, one can stimulate the regeneration of functional vasculature network locally, re-perfuse the ischemic tissue, and thus salvage the limb. Here we review recent advance in nanomaterials, and discuss how their application can improve and facilitate growth factor or cell therapies. Specifically, nanoparticles (NPs) can serve as drug carrier and target to ischemic tissues and achieve localized and sustained release of pro-angiogenic proteins. As nonviral vectors, NPs can greatly enhance the transfection of target cells with pro-angiogenic genes with relatively fewer safety concern. Further, NPs may also be used in combination with cell therapy to enhance cell retention, cell survival and secretion of angiogenic factors. Lastly, nano/micro fibrous vascular grafts can be engineered to better mimic the structure and composition of native vessels, and hopefully overcome many complications/limitations associated with conventional synthetic grafts.

Obesity as a risk and severity factor in rheumatic diseases (autoimmune chronic inflammatory diseases)

The growing body of evidence recognizing the adipose tissue (AT) as an active endocrine organ secreting bioactive mediators involved in metabolic and inflammatory disorders, together with the global epidemic of overweight and obesity, rise obesity as a hot topic of current research. The chronic state of low-grade inflammation present in the obese condition and the multiple pleiotropic effects of adipokines on the immune system has been implicated in the pathogenesis of several inflammatory conditions including rheumatic autoimmune and inflammatory diseases. We will discuss the main relevant evidences on the role of the AT on immune and inflammatory networks and the more recent evidences regarding the effects of obesity on the incidence and outcomes of the major autoimmune chronic inflammatory diseases.