Neurogenesis of Rhesus adipose stromal cells

Progress in stem cell therapy for the diabetic foot

The diabetic foot is a common and severe complication of diabetes comprising a group of lesions including vasculopathy, neuropathy, tissue damage and infection. Vasculopathy due to ischemia is a major contributor to the pathogenesis, natural history and outcome of the diabetic foot. Despite conventional revascularization interventions including angioplasty, stenting, atherectomy and bypass grafts to vessels, a high incidence of amputation persists. The need to develop alternative therapeutic options is compelling; stem cell therapy aims to increase revascularization and alleviate limb ischemia or improve wound healing by stimulating new blood vessel formation, and brings new hope for the treatment of the diabetic foot.

Novel GSK-3β inhibitors and CBM-1078 guide hATSCs' deaging via Oct4 and β-catenin activation

Abstract Aims: The fate decision of adult stem cells is determined by the activation of specific intracellular signaling pathways after exposure to specific stimuli. In this study, we demonstrated specific functions of a novel small molecule, CBM-1078, that induced cell self-renewal via Oct4- and canonical Wnt/β-catenin-mediated deaging in cultured human adipose tissue-derived stem cells (hATSCs).

RESULTS

As a potential glycogen synthase kinase-3β (GSK-3β) inhibitor, CBM-1078 primarily activated β-catenin and Oct4 expression after inhibition of GSK-3β. Treatment of hATSCs with CBM-1078 led to transdifferentiation toward a neural precursor cell fate after transient self-renewal, and the cells were capable of differentiation into gamma-Aminobutyric acid (GABA)-secreting neuronal cells with pain-modulating functions in an animal model of neuropathic pain. During cell self-renewal, CBM-1078 directs the translocalization of β-catenin and Oct4 into the nucleus, an event that is crucial for the cooperative activation of hATSC neurogenesis via Oct4 and Wnt/β-catenin. Nuclear-localized β-catenin and Oct4 act together to regulate the expression of Oct4, Nanog, Sox2, β-catenin, c-Myc, and STAT3 after binding to the regulatory regions of these genes. Nuclear Oct4 and Wnt3a/β-catenin also control cell growth by binding to the promoters of STAT3, Gli3, and c-Myc after complex formation and direct interaction. CBM-1078 actively enhanced the DNA-binding affinity of Oct4 and β-catenin to functional genes and activated the Wnt/β-catenin pathway to promote hATSC reprogramming.

INNOVATION AND CONCLUSION

This study revealed the value of a single small molecule, CBM-1078, showing a definitive cell reprogramming mechanism. Finally, we confirmed the therapeutic potential of GABA-hATSCs for treatment of neuropathic pain, which could be used for therapeutic purposes in humans. Antioxid. Redox Signal. 00, 000-000.

Autologous stem cells for personalised medicine

Increasing understanding of stem cell biology, the ability to reprogramme differentiated cells to a pluripotent state and evidence of multipotency in certain adult somatic stem cells has opened the door to exciting therapeutic advances as well as a great deal of regulatory and ethical issues. Benefits will come from the possibility of modelling human diseases and develop individualised therapies, and from their use in transplantation and bioengineering. The use of autologous stem cells is highly desirable, as it avoids the problem of tissue rejection, and also reduces ethical and regulatory issues. Identification of the most appropriate cell sources for different potential applications, development of appropriate clinical grade methodologies and large scale well controlled clinical trials will be essential to assess safety and value of cell based therapies, which have been generating much hope, but are by and large not yet close to becoming standard clinical practice. We briefly discuss stem cells in the context of tissue repair and regenerative medicine, with a focus on individualised clinical approaches, and give examples of sources of autologous cells with potential for clinical intervention.

Spheroid formation and neural induction in human adipose-derived stem cells on a chitosan-coated surface

The application of stem cells appears to have great therapeutic potential to facilitate nerve regeneration in patients with neurodegenerative disease or spinal cord injury. Human adipose-derived stem cells (hADSCs), a subset of multipotent mesenchymal stem cells, possess the great advantages of an abundant amount of cells, less ethical conflict and minimal invasive surgical procedures to obtain the cells. Chitosan, a naturally derived polysaccharide from chitin, has been widely studied to facilitate and guide the direction of nerve regeneration as a biomaterial for the neural tube. Chitosan also serves as a three-dimensional culture substrate to facilitate cellular sphere formation among various cells but is as yet unexplored in hADSCs. In this study, the ability of hADSCs to transdifferentiate from the mesenchymal into the neural lineage by seeding hADSCs on a chitosan-coated surface to form therapeutic cell spheres was investigated. The optimal seeding density (2 × 10(4) cells/cm(2)) and harvesting time (72 h) to obtain sphere formation were determined by cell viability on a chitosan-coated surface. Expression of neural lineage markers was observed by immunofluorescent staining of nestin, neurofilament heavy chain and glial fibrillary acidic protein. The neural induction potentials were also provoked by replating spheres from primary to tertiary passages. The effect of neural induction in hADSCs on a chitosan-coated surface may help to provide cell sources for facilitating nerve regeneration in future clinical applications.

Stability of neural differentiation in human adipose derived stem cells by two induction protocols

There are some evidences for suggesting that adipose derived stem cells (ADSCs) can be differentiated to the fate of neural cell type. ADSCs can be expanded rapidly in vitro and can be obtained by a less invasive method. In this study, we attempted to compare the stability of neural differentiation in human ADSCs by using two induction protocols. Isolated ADSCs were induced into neural-like cells using diverse effects of two specific procedures. For protocol 1, ADSCs were induced by chemical induction. In protocol 2, ADSCs were treated for sphere formation. Then, the singled cells were cultured in neurobasal media supplemented with special components. Differentiated ADSCs were evaluated for Nestin, MAP2 and GFAP expression by immunocytochemistry and semi quantitative RT-PCR techniques. Moreover, MTT assay was employed to detect cell viability and proliferation. Immunocytochemical analysis of both protocols demonstrated that ADSCs had large expression of the neural-specific markers. In RT-PCR, protocol 1 showed the highest percentage of MAP2 expression, but with time passing, the neural like state was reversible. Protocol 2 found with express of Nestin at week 1, however MAP2 and GFAP expression increased after 3 weeks. The neural-like cells produced by protocol 1 led to the further cell death. Comparative analysis showed that neural-like cell differentiation of ADSCs in chemical induction protocol was rapid but transitory, while it was approximately steady in neurosphere formation protocol.

Use of adipose-derived stem cells to fabricate scaffoldless tissue-engineered neural conduits in vitro

Peripheral nerve injuries resulting from trauma or disease often necessitate surgical intervention. Although the gold standard for such repairs uses nerve autografts, alternatives that do not require invasive harvesting of autologous nerve tissues are currently being designed and evaluated. We previously established the use of scaffoldless engineered neural conduits (ENCs) fabricated from primary cells as one such alternative in sciatic nerve repair in rats [Baltich et al. (2010) In Vitro Cell Dev Biol Anim 46(5):438-444]. The present study establishes protocols for fabricating neural conduits from adipose-derived stem cells (ASCs) differentiated to either a fibroblast or neural lineage and co-cultured into a three-dimensional (3-D) scaffoldless tissue-ENC. Addition of ascorbic acid-2-phosphate and fibroblast growth factor (FGF)-2 to the medium induced and differentiated ASCs to a fibroblast lineage in more than 90% of the cell population, as confirmed by collagen I expression. ASC-differentiated fibroblasts formed monolayers, delaminated, and formed 3-D conduits. Neurospheres were formed by culturing ASCs on non-adherent surfaces in serum-free neurobasal medium with the addition of epidermal growth factor (EGF) and FGF-2. The addition of 10 ng EGF and 10 ng FGF-2 produced larger and more numerous neurospheres than treatments of lower EGF and FGF-2 concentrations. Subsequent differentiation to glial-like cells was confirmed by the expression of S100. ASC-derived fibroblast monolayers and neurospheres were co-cultured to fabricate a 3-D scaffoldless tissue-ENC. Their nerve-like structure and incorporation of glial-like cells, which would associate with regenerating axons, may make these novel, stem cell-derived neural conduits an efficacious technology for repairing critical gaps following peripheral nerve injury.

The dual origin of the peripheral olfactory system: placode and neural crest

BACKGROUND

The olfactory epithelium (OE) has a unique capacity for continuous neurogenesis, extending axons to the olfactory bulb with the assistance of olfactory ensheathing cells (OECs). The OE and OECs have been believed to develop solely from the olfactory placode, while the neural crest (NC) cells have been believed to contribute only the underlying structural elements of the olfactory system. In order to further elucidate the role of NC cells in olfactory development, we examined the olfactory system in the transgenic mice Wnt1-Cre/Floxed-EGFP and P0-Cre/Floxed-EGFP, in which migrating NC cells and its descendents permanently express GFP, and conducted transposon-mediated cell lineage tracing studies in chick embryos.

RESULTS

Examination of these transgenic mice revealed GFP-positive cells in the OE, demonstrating that NC-derived cells give rise to OE cells with morphologic and antigenic properties identical to placode-derived cells. OECs were also positive for GFP, confirming their NC origin. Cell lineage tracing studies performed in chick embryos confirmed the migration of NC cells into the OE. Furthermore, spheres cultured from the dissociated cells of the olfactory mucosa demonstrated self-renewal and trilineage differentiation capacities (neurons, glial cells, and myofibroblasts), demonstrating the presence of NC progenitors in the olfactory mucosa.

CONCLUSION

Our data demonstrates that the NC plays a larger role in the development of the olfactory system than previously believed, and suggests that NC-derived cells may in part be responsible for the remarkable capacity of the OE for neurogenesis and regeneration.

Interleukin-8 derived from local tissue-resident stromal cells promotes tumor cell invasion

The aim of this study is to evaluate the role of adipose tissue resident stromal cells on tumor cell invasion. Our data show that a subpopulation of adipose tissue derived stromal cells expressing Nestin, NG2, α-smooth muscle actin and PDGFR-α migrate toward the cancer cells. Microarray analysis revealed the upregulation of IL-8 in the migrated cells. We demonstrated that stromal cell derived IL-8 promote the invasion and the anchorage-independent growth of cancer cells. We conclude that human breast cancer cells attract a subpopulation of stromal cells that secrete IL-8 to promote tumor cell invasion in a paracrine fashion.

Wnt5a-mediating neurogenesis of human adipose tissue-derived stem cells in a 3D microfluidic cell culture system

In stem cell biology, cell plasticity refers to the ability of stem cells to differentiate into a variety of cell lineages. Recently, cell plasticity has been used to refer to the ability of a given cell type to reversibly de-differentiate, re-differentiate, or transdifferentiate in response to specific stimuli. These processes are regulated by multiple intracellular and extracellular growth and differentiation factors, including low oxygen. Our recent study showed that 3D microfluidic cell culture induces activation of the Wnt5A/β-catenin signaling pathway in hATSCs (human Adipose Tissue-derived Stem Cells). This resulted in self renewal and transdifferentiation of hATSCs into neurons. To improve neurogenic potency of hATSCs in response to low oxygen and other unknown physical factors, we developed a gel-free 3D microfluidic cell culture system (3D-μFCCS). The functional structure was developed for the immobilization of 3D multi-cellular aggregates in a microfluidic channel without the use of a matrix on the chip. Growth of hATSCs neurosphere grown on a chip was higher than the growth of control cells grown in a culture dish. Induction of differentiation in the Chip system resulted in a significant increase in the induction of neuronal-like cell structures and the presentation of TuJ or NF160 positive long neuritis compared to control cells after active migration from the center of the microfluidic channel layer to the outside of the microfluidic channel layer. We also observed that the chip neurogenesis system induced a significantly higher level of GABA secreting neurons and, in addition, almost 60% of cells were GABA + cells. Finally, we observed that 1 month of after the transplantation of each cell type in a mouse SCI lesion, chip cultured and neuronal differentiated hATSCs exhibited the ability to effectively transdifferentiate into NF160 + motor neurons at a high ratio. Interestingly, our CHIP/PCR analysis revealed that HIF1α-induced hATSCs neurogenesis on the chip. This induction was a result of the direct binding of HIF1α to the regulatory regions of the Oct4 and β-catenin genes in nucleus. In the Chip culture of hATSCs that we developed, a low oxygen microenvironment was induced. The low oxygen level induced HIF1α expression, which resulted in increased expression of Wnt5A/β-catenin and Oct4 via the direct binding of HIF1α to the regulatory regions of β-catenin and Oct4.

Neurogenesis of adipose-derived stem cells in hydrogel

Adipose tissue is a readily available source of adult stem cells with multipotent properties suitable for tissue engineering and regenerative medical applications. Peptide hydrogel is a novel biomaterial which provides three-dimensional microenvironments for a variety of cells for tissue grafting. In this study, adipose-derived stem cells (ADSCs) were isolated from rats, seeded into the peptide hydrogel polymer scaffolds and cultured in Neurobasal (NB) media supplemented with B27, basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF). Ten days after the culture, some cells were expanded into clonal populations in which the expression of both Nestin and Brdu was detected but only Brdu expression was detected in the cells that were not expanded into clonal populations. Our results suggested that ADSCs in peptide hydrogel polymer scaffolds can be induced to differentiate into cells capable of expressing the neuron-associated markers, self-renewal and self-propagation.

Tendon tissue engineering: adipose-derived stem cell and GDF-5 mediated regeneration using electrospun matrix systems

Tendon tissue engineering with a biomaterial scaffold that mimics the tendon extracellular matrix (ECM) and is biomechanically suitable, and when combined with readily available autologous cells, may provide successful regeneration of defects in tendon. Current repair strategies using suitable autografts and freeze-dried allografts lead to a slow repair process that is sub-optimal and fails to restore function, particularly in difficult clinical situations such as zone II flexor tendon injuries of the hand. We have investigated the effect of GDF-5 on cell proliferation and gene expression by primary rat adipose-derived stem cells (ADSCs) that were cultured on a poly(DL-lactide-co-glycolide) PLAGA fiber scaffold and compared to a PLAGA 2D film scaffold. The electrospun scaffold mimics the collagen fiber bundles present in native tendon tissue, and supports the adhesion and proliferation of multipotent ADSCs. Gene expression of scleraxis, the neotendon marker, was upregulated seven- to eightfold at 1 week with GDF-5 treatment when cultured on a 3D electrospun scaffold, and was significantly higher at 2 weeks compared to 2D films with or without GDF-5 treatment. Expression of the genes that encode the major tendon ECM protein, collagen type I, was increased by fourfold starting at 1 week on treatment with 100 ng mL(-1) GDF-5, and at all time points the expression was significantly higher compared to 2D films irrespective of GDF-5 treatment. Thus stimulation with GDF-5 can modulate primary ADSCs on a PLAGA fiber scaffold to produce a soft, collagenous musculoskeletal tissue that fulfills the need for tendon regeneration.

Stem cells from adipose tissue

This is a review of the growing scientific interest in the developmental plasticity and therapeutic potential of stromal cells isolated from adipose tissue. Adipose-derived stem/stromal cells (ASCs) are multipotent somatic stem cells that are abundant in fat tissue. It has been shown that ASCs can differentiate into several lineages, including adipose cells, chondrocytes, osteoblasts, neuronal cells, endothelial cells, and cardiomyocytes. At the same time, adipose tissue can be harvested by a minimally invasive procedure, which makes it a promising source of adult stem cells. Therefore, it is believed that ASCs may become an alternative to the currently available adult stem cells (e.g. bone marrow stromal cells) for potential use in regenerative medicine. In this review, we present the basic information about the field of adipose-derived stem cells and their potential use in various applications.

Long-term in vivo regeneration of peripheral nerves through bioengineered nerve grafts

Although autologous nerve graft is still the first choice strategy in nerve reconstruction, it has the severe disadvantage of the sacrifice of a functional nerve. Cell transplantation in a bioartificial conduit is an alternative strategy to improve nerve regeneration. Nerve fibrin conduits were seeded with various cell types: primary Schwann cells (SC), SC-like differentiated bone marrow-derived mesenchymal stem cells (dMSC), SC-like differentiated adipose-derived stem cells (dASC). Two further control groups were fibrin conduits without cells and autografts. Conduits were used to bridge a 1 cm rat sciatic nerve gap in a long term experiment (16 weeks). Functional and morphological properties of regenerated nerves were investigated. A reduction in muscle atrophy was observed in the autograft and in all cell-seeded groups, when compared with the empty fibrin conduits. SC showed significant improvement in axon myelination and average fiber diameter of the regenerated nerves. dASC were the most effective cell population in terms of improvement of axonal and fiber diameter, evoked potentials at the level of the gastrocnemius muscle and regeneration of motoneurons, similar to the autografts. Given these results and other advantages of adipose derived stem cells such as ease of harvest and relative abundance, dASC could be a clinically translatable route towards new methods to enhance peripheral nerve repair.

Isolation and culture of rhesus adipose-derived stem cells

Adipose tissue is as an abundant and accessible source of stem cells with multipotent properties suitable for tissue engineering and regenerative medical applications. Rhesus monkeys are physiologically and phylogenetically similar to humans, and they and their cells are valuable for biomedical research and evaluation of preclinical therapies. Here, we describe methods for the isolation, culture, and differentiation of rhesus adipose-derived stem cells (rASCs).

A novel method for the isolation of subpopulations of rat adipose stem cells with different proliferation and osteogenic differentiation potentials

Bone marrow has been the elected cell source of studies published so far concerning bone and cartilage tissue-engineering approaches. Recent studies indicate that adipose tissue presents significant advantages over bone marrow as a cell source for tissue engineering. Most of these studies report the use of adipose stem cells (ASCs) isolated by a method based on the enzymatic digestion of the adipose tissue and on the ability of stem cells to adhere to a cell culture plastic surface. Using this method, a heterogeneous population was obtained containing different cell types that have been shown to compromise the proliferation and differentiation potential of the stem cells. This paper reports the development and optimization of a new isolation method that enables purified cell populations to be obtained that exhibit higher osteogenic differentiation and/or proliferation potential. This method is based on the use of immunomagnetic beads coated with specific antibodies and it is compared with other methods described in the literature for the selection of stem cell populations, e.g. methods based on a gradient solution and enzymatic digestion. The results showed that the isolation method based on immunomagnetic beads allows distinct subpopulations of rat ASCs to be isolated, showing different stem cells marker expressions and different osteogenic differentiation potentials. Therefore, this method can be used to study niches in ASC populations and/or also allow adipose tissue to be used as a stem cell source in a more efficient manner, increasing the potential of this cell source in future clinical applications.

Native human adipose stromal cells: localization, morphology and phenotype

Objectives:

Beside having roles in energy homeostasis and endocrine modulation, adipose tissue (AT) is now considered a promising source of mesenchymal stromal cells (adipose-derived stromal cells or ASCs) for regenerative medicine. Despite numerous studies on cultured ASCs, native human ASCs are rarely investigated. Indeed, the phenotype of ASCs in their native state, their localization within AT and comparison with bone marrow-derived mesenchymal stromal cells (BM-MSCs) has been poorly investigated.

Design:

To address these issues, the stroma vascular fraction (SVF) of human AT was extracted and native cell subtypes were isolated by immunoselection to study their clonogenic potential in culture. Immunohistology on samples of human AT in combination with reconstruction of confocal sections were performed in order to localize ASCs.

Results:

Compared with BM-MNCs, all native ASCs were found in the CD34⁺ cell fraction of the AT-SVF. Native ASCs expressed classical mesenchymal markers described for BM-MSCs. Interestingly, CD34 expression decreased during ASC cell culture and was negatively correlated with cell proliferation rate. Immunohistological analysis revealed that native ASCs exhibited specific morphological features with protrusions. They were found scattered in AT stroma and did not express in vivo pericytic markers such as NG2, CD140b or alpha-smooth muscle actin, which appeared during the culture process. Finally, ASCs spontaneous commitment to adipocytic lineage was enhanced in AT from obese humans.

Conclusions:

The use of complementary methodological approaches to study native human ASCs revealed their immunophenotype, their specific morphology, their location within AT and their stemness. Furthermore, our data strongly suggest that human ASCs participate in adipogenesis during AT development.

Neural differentiation of human adipose tissue-derived stem cells

While adult stem cells can be induced to transdifferentiate into multiple lineages of cells or tissues, their plasticity and utility for human therapy remains controversial. In this chapter, we describe methods for the transdifferentiation of human adipose tissue-derived stem cells (ASCs) along neural lineages using in vitro and in vivo systems. The in vitro neural differentiation of ASCs has been reported by several groups using serum-free cytokine induction, butylated hydroxyanisole (BHA) chemical induction, and neurosphere formation in combination with the cytokines, such as brain-derived neurotrophic factor (BDNF) and basic fibroblast growth factor (bFGF). For in vivo neurogenic induction, ASCs are treated with BDNF and bFGF to form neurospheres in vitro and then delivered directly to the brain. In this chapter, several detailed protocols for the effective neurogenic induction of ASCs in vitro and in vivo are described. The protocols described herein can be applied to further molecular and mechanistic studies of neurogenic induction and differentiation of ASCs. In addition, these methods can be useful for differentiating ASCs for therapeutic intervention in central nervous system disorders.

Neurogenic transdifferentiation of human adipose-derived stem cells? A critical protocol reevaluation with special emphasis on cell proliferation and cell cycle alterations

Adipose-derived stem cells (ASCs) are reported to display multilineage differentiation potential, including neuroectodermal pathways. The aim of the present study was to critically re-evaluate the potential neurogenic (trans-)differentiation capacity of ASCs using a neurogenic induction protocol based on the combination of isobutylmethylxanthine (IBMX), indomethacin and insulin. ASCs isolated from lipo-aspirate samples of five healthy female donors were characterized and potential neurogenic (trans-)differentiation was assessed by means of immunohistochemistry and gene expression analyses. Cell proliferation and cell cycle alterations were studied, and the expression of CREB/ATF transcription factors was analyzed. ASCs expressed CD59, CD90 and CD105, and were tested negative for CD34 and CD45. Under neurogenic induction, ASCs adopted a characteristic morphology comparable to neur(on)al progenitors and expressed musashi1, β-III-tubulin and nestin. Gene expression analyses revealed an increased expression of β-III-tubulin, GFAP, vimentin and BDNF, as well as SOX4 in induced ASCs. Cell proliferation was significantly reduced under neurogenic induction; cell cycle analyses showed a G2-cell cycle arrest accompanied by differential expression of key regulators of cell cycle progression. Differential expression of CREB/ATF transcription factors could be observed on neurogenic induction, pointing to a decisive role of the cAMP-CREB/ATF system. Our findings may point to a potential neurogenic (trans-)differentiation of ASCs into early neur(on)al progenitors, but do not present definite evidence for it. Especially, the adoption of a neural progenitor cell-like morphology must not automatically be misinterpreted as a specific characteristic of a respective (trans-)differentiation process, as this may as well be caused by alterations of cell cycle progression.

Stem cells in bone tissue engineering

Bone tissue engineering has been one of the most promising areas of research, providing a potential clinical application to cure bone defects. Recently, various stem cells including embryonic stem cells (ESCs), bone marrow-derived mesenchymal stem cells (BM-MSCs), umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs), adipose tissue-derived stem cells (ADSCs), muscle-derived stem cells (MDSCs) and dental pulp stem cells (DPSCs) have received extensive attention in the field of bone tissue engineering due to their distinct biological capability to differentiate into osteogenic lineages. The application of these stem cells to bone tissue engineering requires inducing in vitro differentiation of these cells into bone forming cells, osteoblasts. For this purpose, efficient in vitro differentiation towards osteogenic lineage requires the development of well-defined and proficient protocols. This would reduce the likelihood of spontaneous differentiation into divergent lineages and increase the available cell source for application to bone tissue engineering therapies. This review provides a critical examination of the various experimental strategies that could be used to direct the differentiation of ESC, BM-MSC, UCB-MSC, ADSC, MDSC and DPSC towards osteogenic lineages and their potential applications in tissue engineering, particularly in the regeneration of bone.

Adipose tissue-derived stem cells and their application in bone and cartilage tissue engineering

The adipose tissue was considered a reserve of energy until the '80s, when it was found that this tissue was involved in the metabolism of sex steroids such as estrogens. From then on, the importance attributed to this tissue radically changed as it was then considered an active organ, involved in important functions of the human body. In 2001, for the first time, the existence of stem cells within this tissue was reported, and since then, this tissue has been gaining an increased importance as a stem cell source for a wide range of potential applications in cell therapies and/or tissue engineering and regenerative medicine strategies, mainly due to its wide availability and easy access. This manuscript provides an overview on adipose stem cells (i.e., adipose tissue-derived stem cells, ASCs) considering the tissue of origin, the niche of the ASCs, and their phenotype in all aspects. In this paper it is also discussed the markers that have been used for the characterization of these cells, their differentiation properties, and their immunological reactivity, reporting studies from 2001 until this date. The ASCs are also compared with bone marrow stem cells (BMSCs), until now considered as the gold standard source of stem cells, underlining the common characteristics and the differences between the stem cells obtained from these two sources, as well as the advantages and disadvantages of their potential use in different applications. Finally, this review will also focus on the potential application of ASCs in tissue engineering applications, particularly in the regeneration of bone and cartilage, commenting on the progress of this approach and future trends of the field.

Rat adipose tissue-derived stem cells transplantation attenuates cardiac dysfunction post infarction and biopolymers enhance cell retention

Background

Cardiac cell transplantation is compromised by low cell retention and poor graft viability. Here, the effects of co-injecting adipose tissue-derived stem cells (ASCs) with biopolymers on cell cardiac retention, ventricular morphometry and performance were evaluated in a rat model of myocardial infarction (MI).

Methodology/Principal Findings

^99mTc-labeled ASCs (1×10⁶ cells) isolated from isogenic Lewis rats were injected 24 hours post-MI using fibrin a, collagen (ASC/C), or culture medium (ASC/M) as vehicle, and cell body distribution was assessed 24 hours later by γ-emission counting of harvested organs. ASC/F and ASC/C groups retained significantly more cells in the myocardium than ASC/M (13.8±2.0 and 26.8±2.4% vs. 4.8±0.7%, respectively). Then, morphometric and direct cardiac functional parameters were evaluated 4 weeks post-MI cell injection. Left ventricle (LV) perimeter and percentage of interstitial collagen in the spare myocardium were significantly attenuated in all ASC-treated groups compared to the non-treated (NT) and control groups (culture medium, fibrin, or collagen alone). Direct hemodynamic assessment under pharmacological stress showed that stroke volume (SV) and left ventricle end-diastolic pressure were preserved in ASC-treated groups regardless of the vehicle used to deliver ASCs. Stroke work (SW), a global index of cardiac function, improved in ASC/M while it normalized when biopolymers were co-injected with ASCs. A positive correlation was observed between cardiac ASCs retention and preservation of SV and improvement in SW post-MI under hemodynamic stress.

Conclusions

We provided direct evidence that intramyocardial injection of ASCs mitigates the negative cardiac remodeling and preserves ventricular function post-MI in rats and these beneficial effects can be further enhanced by administrating co-injection of ASCs with biopolymers.

Soluble factors from ASCs effectively direct control of chondrogenic fate

BACKGROUND AND OBJECTIVES

Adipose tissue-derived stem cells (ASCs) have great potential for regenerative medicine. For molecular understanding of specific functional molecules present in ASCs, we analysed 756 proteins including specific chondrogenic functional factors, using high-throughput nano reverse-phase liquid chromatography-electrospray ionization-tandem mass spectrometry.

MATERIALS, METHODS AND RESULTS

Of these proteins, 33 were identified as chondrogenic factors or proteins including type 2 collagen, biglycan, insulin-like growth factor-binding protein and transforming growth factor-beta 1 (TGF-beta1). ASCs are a possible cell source for cartilage regeneration as they are able to secrete a number of functional cytokines including chondrogenesis-inducing molecules such as TGF-beta1 and bone morphogenetic protein 4 (BMP4). The chondrogenic phenotype of cultured ASCs was effectively induced by ASC-culture media (CM) containing BMP4 and TGF-beta1, and maintained after pre-treatment for 14 days in vitro and subcutaneous implantation in vivo. Chondrogenic differentiation efficiency of cultured ASCs and cultured mouse skin-derived progenitor cells (SPCs) depended absolutely on ASC CM-fold concentration. Cell density was also a very important factor for chondrogenic behaviour development during differentiation of ASCs and SPCs.

CONCLUSION

ASC CM-derived TGF-beta1-induced chondrogenic differentiation of ASCs resulted in significant reduction in chondrogenic activity after inhibition of the p38 pathway, revealing involvement of this MAPK pathway in TGF-beta1 signalling. On the other hand, TGF-beta1 signalling also led to SMAD activation that could directly increase chondrogenic activity of ASCs.

The adipose-derived stem cell: looking back and looking ahead

In 2002, researchers at UCLA published a manuscript in Molecular Biology of the Cell describing a novel adult stem cell population isolated from adipose tissue-the adipose-derived stem cell (ASC). Since that time, the ASC has gone on to be one of the most popular adult stem cell populations currently being used in the stem cell field. With multilineage mesodermal potential and possible ectodermal and endodermal potentials also, the ASC could conceivably be an alternate to pluripotent ES cells in both the lab and in the clinic. In this retrospective article, a historical perspective on the ASC is given together with exciting new applications for the stem cell being considered today.

Neurogenic differentiation of murine adipose derived stem cells transfected with EGFP in vitro

Some studies indicate that adipose derived stem cells (ADSCs) can differentiate into adipogenic, chondrogenic, myogenic, and osteogenic cells in vitro. However, whether ADSCs can be induced to differentiate into neural cells in vitro has not been clearly demonstrated. In this study, the ADSCs isolated from the murine adipose tissue were cultured and transfected with the EGFP gene, and then the cells were induced for neural differentiation. The morphology of those ADSCs began to change within two days which developed into characteristics of round cell bodies with several branching extensions, concomitantly expressing EGFP fluorescence. Approximately 60% of the total cell populations were bipolar or multipolar in shape. Some of them appeared to make contact with their neighboring cells. RT-PCR, Western blot and Immunocytochemistry revealed that the expression levels of the markers of neurons and oligodendrocytes such as MAP2, NF-70, Neu N and RIP upon neural induction were increased, but the expression of the special marker of astrocytes, GFAP, was undetectable until 96 h after induction when a small signal was observed. It was concluded that the ADSCs transfected with EGFP possessed the ability to undergo morphologic and phenotypic changes consistent with neural differentiation in vitro. It suggests that these cells might provide an ideal source for further stem cell research with possible therapeutic application for spinal cord injury.

DHP-derivative and low oxygen tension effectively induces human adipose stromal cell reprogramming

BACKGROUND AND METHODS

In this study, we utilized a combination of low oxygen tension and a novel anti-oxidant, 4-(3,4-dihydroxy-phenyl)-derivative (DHP-d) to directly induce adipose tissue stromal cells (ATSC) to de-differentiate into more primitive stem cells. De-differentiated ATSCs was overexpress stemness genes, Rex-1, Oct-4, Sox-2, and Nanog. Additionally, demethylation of the regulatory regions of Rex-1, stemnesses, and HIF1alpha and scavenging of reactive oxygen species were finally resulted in an improved stem cell behavior of de-differentiate ATSC (de-ATSC). Proliferation activity of ATSCs after dedifferentiation was induced by REX1, Oct4, and JAK/STAT3 directly or indirectly. De-ATSCs showed increased migration activity that mediated by P38/JUNK and ERK phosphorylation. Moreover, regenerative efficacy of de-ATSC engrafted spinal cord-injured rats and chemical-induced diabetes animals were significantly restored their functions.

CONCLUSIONS/SIGNIFICANCE

Our stem cell remodeling system may provide a good model which would provide insight into the molecular mechanisms underlying ATSC proliferation and transdifferentiation. Also, these multipotent stem cells can be harvested may provide us with a valuable reservoir of primitive and autologous stem cells for use in a broad spectrum of regenerative cell-based disease therapy.

Distribution of adipose-derived stem cells in adipose tissues from human cadavers

BACKGROUND

Adipose-derived stem cells (ASCs) possess multipotency in vivo and in vitro, and thus are thought to be very promising precursors for use in regenerative medicine. ASCs can be concentrated from adipose tissue by enzymatic digestion and transplanted to increase angiogenesis or for cosmesis. ASC transplants are now being performed in a clinical setting. Although data on ASCs are extensive, the distribution of ASCs in human fat tissue has not been fully clarified. Thus, it is important to identify the distribution of ASCs to obtain cell populations rich in ASCs for clinical use.

METHODS

ASCs express CD34, a cell surface marker. As CD34 is also expressed by endothelial cells, we immunohistochemically stained 2-μm-thick serial paraffin sections of fat tissue obtained from various parts of formalin-fixed cadavers with anti-CD31 and anti-CD34 antibodies to distinguish ASCs from endothelial cells.

RESULTS

CD34(+)/CD31(-) cells were mainly found in connective tissue tracts and perivascularly. Among fat tissues obtained from various sites, fat tissues in the thoracic back and lower abdomen were richest in CD34(+)/CD31(-) cells.

CONCLUSION

The concentrations of CD34(+)/CD31(-) cells in adipose tissues differ between sites. The sites most highly enriched for ASCs were identified, and it is now possible to select the best sites for collection of ASCs for transplantation.

Slowed progression in models of Huntington disease by adipose stem cell transplantation

OBJECTIVE

Adipose-derived stem cells (ASCs) are readily accessible and secrete multiple growth factors. Here, we show that ASC transplantation rescues the striatal pathology of Huntington disease (HD) models.

METHODS

ASCs were isolated from human subcutaneous adipose tissue. In a quinolinic acid (QA)-induced rat model of striatal degeneration, human ASCs (1 million cells) were transplanted into the ipsilateral striatal border immediately after the QA injection. In 60-day-old R6/2 mice transgenic for HD, ASCs (0.5 million cells) were transplanted into each bilateral striata. In in vitro experiments, we treated mutant huntingtin gene-transfected cerebral neurons with ASC-conditioned media.

RESULTS

In the QA model, human ASCs reduced apomorphine-induced rotation behavior, lesion volume, and striatal apoptosis. In R6/2 transgenic mice, transplantation of ASCs improved Rota-Rod performance and limb clasping, increased survival, attenuated the loss of striatal neurons, and reduced the huntingtin aggregates. ASC-transplanted R6/2 mice expressed elevated levels of peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1alpha) and reactive oxygen defense enzymes and showed activation of the Akt/cAMP-response element-binding proteins. ASC-conditioned media decreased the level of N-terminal fragments of mutant huntingtin and associated apoptosis, and increased PGC-1alpha expression.

INTERPRETATION

Collectively, ASC transplantation slowed striatal degeneration and behavioral deterioration of HD models, possibly via secreted factors.

Comparison of the efficiencies of three neural induction protocols in human adipose stromal cells

The aim of this study was to compare the neural differentiation potential and the expression of neurotrophic factors (NTFs) in differentiated adipose-derived stem cells (ADSCs) using three established induction protocols, serum free (Protocol 1), chemical reagents (Protocol 2), and spontaneous (Protocol 3) protocols. Protocol 1 produced the highest percentage of mature neural-like cells (MAP2ab(+)). Protocol 2 showed the highest percentage of immature neural-like cells (beta-tubulin III(+)), but the neural-like state was transient and reversible. Protocol 3 caused ADSCs to differentiate spontaneously into immature neural-like cells, but not into mature neural cell types. The neural-like cells produced by Protocol 1 lived the longest in culture with little cell death, but Protocol 2 and 3 led to the significant cell death. Therefore, Protocol 1 is the most efficient among these protocols. Additionally, soon after differentiation, the mRNA levels of nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) in dADSCs were sharply decreased by Protocol 1 and 2 (acute induction protocol), but not by Protocol 3 (chronic induction protocol). The results indicate that NTFs played an important role in neural differentiation via acute responses to NGF and BDNF, but not chronically during the transdifferentiation process.

IFATS collection: The conditioned media of adipose stromal cells protect against hypoxia-ischemia-induced brain damage in neonatal rats

Adipose tissue stroma contains a population of mesenchymal stem cells, which support repair when administered to damaged tissues, in large part through secreted trophic factors. We directly tested the ability of media collected from cultured adipose-derived stem cells (ASCs) to protect neurons in a rat model of brain hypoxic-ischemic (HI) injury. Concentrated conditioned medium from cultured rat ASCs (ASC-CM) or control medium was infused through the jugular vein of neonatal Sprague-Dawley rats subjected to HI injury. The ASC-CM was administered either 1 hour before or 24 hours after induction of injury. Analysis at 1 week indicated that administration at both time points significantly protected against hippocampal and cortical volume loss. Analysis of parallel groups for behavioral and learning changes at 2 months postischemia demonstrated that both treated groups performed significantly better than the controls in Morris water maze functional tests. Subsequent post-mortem evaluation of brain damage at the 2-month time point confirmed neuronal loss to be similar to that observed at 1 week for all groups. We have identified several neurotrophic factors in ASC-CM, particularly insulin-like growth factor-1 and brain-derived neurotrophic factor, which are important factors that could contribute to the protective effects of ASCs observed in studies with both in vitro and in vivo neuronal injury models. These data suggest that delivery of the milieu of factors secreted by ASCs may be a viable therapeutic option for treatment of HI, as well as other brain injuries.

Altered migration and adhesion potential of pro-neurally converted human bone marrow stromal cells

BACKGROUND

Bone marrow (BM)-derived mesenchymal stromal cells (MSC) are promising candidate cells for the development of neuroregenerative therapies. We have previously introduced the pro-neural conversion of human MSC to neural stem cell-like cells (m-NSC) by culturing them in suspension culture under serum-free conditions.

METHODS

In the present study, we used a modified Boyden chamber assay to study the influence of various chemoattractants and extracellular matrix components on MSC and m-NSC migration in vitro. The underlying mechanisms were investigated further by applying real-time reverse transcriptase (RT)-polymerase chain reaction (PCR) and flow cytometry.

RESULTS

The basal migration of m-NSC was significantly reduced compared with MSC (six versus 27 out of 10,000 cells migrated within 6 h). We evaluated the effects of bone morphogenic protein 2 (BMP2), insulin-like growth factor 1 (IGF1), platelet-derived growth factor bb (PDGFbb), vascular endothelial growth factor (VEGFa), and stromal cell-derived factor 1 (SDF1) on the migration potential of both cell types and PDGFbb proved to be the most potent stimulant of migration (235 versus 198 m-NSC or MSC migrated). Adhesion of m-NSC to the filter membrane was delayed and not affected by IGF1 or PDGFbb: 90% of MSC, but only 20% of m-NSC, adhered within 1 h, with 90% of m-NSC adhering within 3 h. However, real-time RT-PCR and flow cytometry revealed an up-regulation of the PDGF receptor B following conversion. Coating the membranes with collagen type I or hyaluronan also significantly influenced cell migration.

DISCUSSION

We could identify major chemoattractive factors for m-NSC and gained partial insight into the complex processes involved in migration of neurally converted cells.

The intracellular distribution of the ES cell totipotent markers OCT4 and Sox2 in adult stem cells differs dramatically according to commercial antibody used

To characterize ES cells, researchers have at their disposal a list of pluripotent markers, such as OCT4. In their quest to determine if adult stem cell populations, such as MSCs and ASCs, are pluripotent, several groups have begun to report the expression of these markers in these cells. Consistent with this, human ASCs (hASCs) are shown in this study to express a plethora of ES pluripotent markers at the gene and protein level, including OCT4, Sox2, and Nanog. When intracellular distribution is examined in hASCs, both OCT4 and Sox2 are expressed within the nuclei of hASCs, consistent with their expression patterns in ES cells. However, a significant amount of expression can be noted within the hASC cytoplasm and a complete absence of nuclear expression is observed for Nanog. Recent descriptions of OCT4 transcript variants may explain the cytoplasmic expression of OCT4 in hASCs and consistent with this, hASCs do express both the OCT4A and 4B transcript variants at the gene level. However, discrepancies arise when these three pluripotent markers are studied at the protein level. Specifically, distinct differences in intracellular expression patterns were noted for OCT4, Sox2, and Nanog from commercial antibody to commercial antibody. These antibody discrepancies persisted when hMSCs and rat ASCs and MSCs were examined. Therefore, confirming the expression of OCT4, Sox2, and Nanog in adult stem cells with today's commercial antibodies must be carefully considered before the designation of pluripotent can be granted.

Transdifferentiation of human adipose tissue-derived stromal cells into insulin-producing clusters

Type 1 diabetes mellitus is caused by autoimmune destruction of insulin-producing beta cells. The major obstacle to transplantation of insulin-producing cells to cure the disease is the limited source of these cells. To overcome this problem, we describe here a multistep protocol for generation of insulin-producing islet-like clusters from human adipose tissue-derived stromal cells (ADSCs). Analysis using reverse transcription polymerase chain reaction detected enhanced expression of various pancreatic genes during the differentiation of ADSCs. Immunofluorescence analysis revealed functional similarities between cells derived from ADSCs and pancreatic islet cells, i.e., the presence of insulin- and C-peptide-coexpressing cells in the clusters and glucagon expression on the cell surface. The glucose challenge tests revealed the production of insulin, and such production was regulated via physiological signaling pathways. Our insulin-producing cells derived from ADSCs could be potentially used for cell therapy of type 1 diabetes mellitus.

The scientific basis for lipotransfer: is it the ideal filler?

A loss of volume results from a reduction in the subcutaneous fat, muscle atrophy, and changes in skeletal framework. Such loss of tissue volume compounded with tissue laxity leads to the aged appearance of the periorbital, perioral, cheek, and mandibular areas. Many facial plastic surgeons have sought to replace this volume with various injectable agents, both synthetic and autologous, in search for the ideal soft tissue filler. This article reviews the literature on lipotransfer and specifically the scientific basis underlying the approach.

Defining stem and progenitor cells within adipose tissue

Adipose tissue-derived stem cells (ADSC) are routinely isolated from the stromal vascular fraction (SVF) of homogenized adipose tissue. Freshly isolated ADSC display surface markers that differ from those of cultured ADSC, but both cell preparations are capable of multipotential differentiation. Recent studies have inferred that these progenitors may reside in a perivascular location where they appeared to coexpress CD34 and smooth muscle actin (alpha-SMA) but not CD31. However, these studies provided only limited histological evidence to support such assertions. In the present study, we employed immunohistochemistry and immunofluorescence to define more precisely the location of ADSC within human adipose tissue. Our results show that alpha-SMA and CD31 localized within smooth muscle and endothelial cells, respectively, in all blood vessels examined. CD34 localized to both the intima (endothelium) and adventitia neither of which expressed alpha-SMA. The niche marker Wnt5a was confined exclusively to the vascular wall within mural smooth muscle cells. Surprisingly, the widely accepted mesenchymal stem cell marker STRO-1 was expressed exclusively in the endothelium of capillaries and arterioles but not in the endothelium of arteries. The embryonic stem cell marker SSEA1 localized to a pericytic location in capillaries and in certain smooth muscle cells of arterioles. Cells expressing the embryonic stem cell markers telomerase and OCT4 were rare and observed only in capillaries. Based on these findings and evidence gathered from the existing literature, we propose that ADSC are vascular precursor (stem) cells at various stages of differentiation. In their native tissue, ADSC at early stages of differentiation can differentiate into tissue-specific cells such as adipocytes. Isolated, ADSC can be induced to differentiate into additional cell types such as osteoblasts and chondrocytes.

Tissue-resident stem cells promote breast cancer growth and metastasis

Mesenchymal stem cells derived from bone marrow have recently been described to localize to breast carcinomas and to integrate into the tumor-associated stroma. In the present study, we investigated whether adipose tissue-derived stem cells (ASCs) could play a role in tumor growth and invasion. Compared with bone marrow-derived cells, ASCs as tissue-resident stem cells are locally adjacent to breast cancer cells and may interact with tumor cells directly. Here, we demonstrate that ASCs cause the cancer to grow significantly faster when added to a murine breast cancer 4T1 cell line. We further show that breast cancer cells enhance the secretion of stromal cell-derived factor-1 from ASCs, which then acts in a paracrine fashion on the cancer cells to enhance their motility, invasion and metastasis. The tumor-promoting effect of ASCs was abolished by knockdown of the chemokine C-X-C receptor 4 in 4T1 tumor cells. We demonstrated that ASCs home to tumor site and promote tumor growth not only when co-injected locally but also when injected intravenously. Furthermore, we demonstrated that ASCs incorporate into tumor vessels and differentiate into endothelial cells. The tumor-promoting effect of tissue-resident stem cells was also tested and validated using a human breast cancer line MDA-MB-231 cells and human adipose tissue-derived stem cells. Our findings indicate that the interaction of local tissue-resident stem cells with tumor stem cells plays an important role in tumor growth and metastasis.

Neuronal differentiation potential of human adipose-derived mesenchymal stem cells

Adult mesenchymal stem cells derived from adipose tissue (A-MSC) have the capacity to differentiate in vitro into mesenchymal as well as endodermal and ectodermal cell lineages. We investigated the neuronal differentiation potential of human A-MSC with a protocol which included sphere formation and sequential culture in brain-derived neurotrophic factor (BDNF) and retinoic acid (RA). After 30 days, about 57% A-MSC showed morphological, immunocytochemical and electrophysiological evidence of initial neuronal differentiation. In fact, A-MSC displayed elongated shape with protrusion of two or three cellular processes, selectively expressed nestin and neuronal molecules (including GABA receptor and tyroxine hydroxilase) in the absence of glial phenotypic markers. Differentiated cells showed negative membrane potential (-60 mV), delayed rectifier potassium currents and TTX-sensitive sodium currents. Such changes were stable for at least 7 days after removal of differentiation medium. In view of these results and the easy availability of adipose tissue, A-MSC may be a ready source of adult MSC with neuronal differentiation potential, an useful tool to treat neurodegenerative diseases.

Derivation, characterization and gene modification of cynomolgus monkey mesenchymal stem cells

Mesenchymal stem cells (MSCs) have received considerable attention in recent years. Particularly exciting is the prospect that MSCs could be differentiated into specialized cells of interest, which could then be used for cell therapy and tissue engineering. MSCs derived from nonhuman primates could be a powerful tool for investigating the differentiation potential in vitro and in vivo for preclinical research. The purpose of this study was to isolate cynomolgus mesenchymal stem cells (cMSCs) from adult bone marrow and characterize their growth properties and multipotency. Mononuclear cells were isolated from cynomolgus monkey bone marrow by density-gradient centrifugation, and adherent fibroblast-like cells grew well in the complete growth medium with 10 microM Tenofovir. cMSCs expressed mesenchymal markers, such as CD29, CD105, CD166 and were negative for hematopoietic markers such as CD34, CD45. Furthermore, the cells were capable of differentiating into osteogenic, chondrogenic, and adipogenic lineages under certain conditions, maintaining normal karyotype throughout extended culture. We also compared different methods (lipofection, nucleofection and lentivirus) for genetic modification of cMSCs and found lentivirus proved to be the most effective method with transduction efficiency of up to 44.6% and lowest level of cell death. The cells after transduction stably expressed green fluorescence protein (GFP) and maintained the abilities to differentiate down osteogenic and adipogenic lineages. In conclusion, these data showed that cMSCs isolated from cynomolgus bone marrow shared similar characteristics with human MSCs and might provide an attractive cell type for cell-based therapy in higher-order mammalian species disorder models.

Myelin-forming ability of Schwann cell-like cells induced from rat adipose-derived stem cells in vitro

Although Schwann cell (SC) transplantation can enhance peripheral and central nerve repair experimentally, it is difficult to generate sufficient SC quickly for clinical application. So alternative cell systems for SC are desired. SC-like cells induced from adipose-derived stem cells (ADSC) may be one of the ideal alternative cell systems for SC. However, myelin-forming ability, which is the most important characteristics and function of SC, has not been investigated in SC-like cells from ADSC up to now. In this experiment, ADSC were harvested from rat inguinal fat pad. Rat ADSC were fibroblast-like in shape, almost all the cells expressed mesodermal marker fibronectin, and only few cells expressed neural stem cell marker nestin. A mixture of glial growth factors (Heregulin, bFGF, PDGF and forskolin) could induce rat ADSC into SC-like cells. SC-like cells were spindle-like in shape and expressed glial markers GFAP and S100, similar to genuine SC. When intracellular cAMP was increased, SC-like cells could express myelin protein p0. More importantly, when co-cultured with rat pheochromocytoma cell line (PC12 cells), SC-like cells could induce the differentiation of PC12 cells rapidly and form myelin structures with PC12 cells in vitro. Our data further demonstrated that SC-like cells from ADSC were able to form myelins and these cells may benefit the treatment of peripheral and central nerve injuries.