Nuclear heterogeneity and proliferative capacity of human adipose derived MSC-like cells

Adipose derived stem cells (ADSCs) are MSC-like cells which could be easily used for regenerative medicine. Here, the morphology and proliferative capacity of human ADSCs is discribed. ADSCs were analyzed after one month of cultivation at a density of 10 cells/cm2. 21 colonies were counted. Few atypical cells (huge nuclei and cytoplasm) were found in 9 out of 17 colonies analyzed. ANOVA demonstrated that colonies also differed (P = 0.0025) in nuclei dimensions and scatter in the dimensions in each colony. Nuclei dimensions and cell density logarithms correlated in reverse proportion (-0.7; P = 0.002). Thus, ADSCs were heterogeneous and represented two types of cells: small highly proliferative and large low proliferative cells. Cell heterogeneity observed in some colonies might be due to cells registered at different cell cycle phases. Stable and typical morphology, colony-formation capability and high proliferative capacity of cells indicate visceral adipose tissue as a rich source of ADSCs.     

Cell culture density affects the proliferation activity of human adipose tissue stem cells

In this study, we investigated the effect of cell density on the proliferation activity of human mesenchymal stem cells (MSCs) derived from adipose tissue (AT‐MSCs) over time in culture. Passage #4 (P4) and #12 (P12) AT‐MSCs from two donors were plated at a density of 200 (culture condition 1, CC1) or 5000 (culture condition 2, CC2) cells cm^?2. After 7 days of incubation, P4 and P12 AT‐MSCs cultured in CC1 were thin and spindle‐shaped, whereas those cultured in CC2 had extensive cell‐to‐cell contacts and an expanded cell volume. In addition, P4 and P12 AT‐MSCs in CC1 divided more than three times, while those in CC2 divided less than once on average. Flow cytometric analysis using 5(6)‐carboxyfluorescein diacetate N‐succinimidyl ester dye showed that the fluorescence intensity of AT‐MSCs was lower in CC1 than in CC2. Furthermore, expression of proliferation‐associated genes, such as CDC45L, CDC20A and KIF20A, in P4 AT‐MSCs was higher in CC1 than in CC2, and this difference was also observed in P12 AT‐MSCs. These data demonstrated that cell culture density affects the proliferation activity of MSCs, suggesting that it is feasible to design a strategy to prepare suitable MSCs using specific culture conditions. Copyright © 2016 John Wiley & Sons, Ltd.     

Influence of oxygen on the proliferation and metabolism of adipose derived adult stem cells

Articular cartilage is an avascular connective tissue that exhibits little intrinsic capacity for repair. Articular cartilage exists in a reduced oxygen ( approximately 5%) environment in vivo; therefore, oxygen tension may be an important factor that regulates the metabolism of chondrocyte progenitors. A number of recent studies have developed tissue engineering approaches for promoting cartilage repair using undifferentiated progenitor cells seeded on biomaterial scaffolds, but little is known about how oxygen might influence these engineered tissues. Human adipose-derived adult stem (hADAS) cells isolated from the stroma of subcutaneous fat were suspended in alginate beads and cultured in control or chondrogenic media in either low oxygen (5%) or atmospheric oxygen tension (20%) for up to 14 days. Under chondrogenic conditions, low oxygen tension significantly inhibited the proliferation of hADAS cells, but induced a two-fold increase in the rate of protein synthesis and a three-fold increase in total collagen synthesis. Low oxygen tension also increased glycosaminoglycan synthesis at certain timepoints. Immunohistochemical analysis showed significant production of cartilage-associated matrix molecules, including collagen type II and chondroitin-4-sulfate. These findings suggest oxygen tension may play an important role in regulating the proliferation and metabolism of hADAS cells as they undergo chondrogenesis, and the exogenous control of oxygen tension may provide a means of increasing the overall accumulation of matrix macromolecules in tissue-engineered cartilage.     

Characterization and comparison of adipose tissue‐derived cells from human subcutaneous and omental adipose tissues

Different fat depots contribute differently to disease and function. These differences may be due to the regional variation in cell types and inherent properties of fat cell progenitors. To address the differences of cell types in the adipose tissue from different depots, the phenotypes of freshly isolated adipose tissue‐derived cells (ATDCs) from subcutaneous (SC) and omental (OM) adipose tissues were compared using flow cytometry. Our results showed that CD31^?CD34⁺CD45^?CD90^‐CD105^?CD146⁺ population, containing vascular smooth muscle cells and pericytes, was specifically defined in the SC adipose tissue while no such population was observed in OM adipose tissue. On the other hand, CD31^?CD34⁺CD45^?CD90^?CD105^?CD146^? population, which is an undefined cell population, were found solely in OM adipose tissue. Overall, the SC adipose tissue contained more ATDCs than OM adipose tissue, while OM adipose tissue contained more blood‐derived cells. Regarding to the inherent properties of fat cell progenitors from the two depots, adipose‐derived stem cells (ADSCs) from SC had higher capacity to differentiate into both adipogenic and osteogenic lineages than those from OM, regardless of that the proliferation rates of ADSCs from both depots were similar. The higher differentiation capacity of ADSCs from SC adipose tissue suggests that SC tissue is more suitable cell source for regenerative medicine than OM adipose tissue. Copyright © 2009 John Wiley & Sons, Ltd.     

Oncostatin M induces proliferation of human adipose tissue-derived mesenchymal stem cells

Interleukin-6 (IL-6) subfamily of cytokines, including oncostatin M (OSM), leukemia inhibitory factor (LIF), and IL-6, has been implicated in a variety of physiological responses, such as cell growth, differentiation, and inflammation. In the present study, we demonstrated that both OSM and LIF stimulated the proliferation of human adipose tissue-derived mesenchymal stem cells (hATSCs), however, IL-6 had no effect on cell proliferation. OSM treatment induced phosphorylation of ERK, and pretreatment with U0126, a MEK inhibitor, prevented the OSM-stimulated proliferation of hATSCs, suggesting that the MEK/ERK pathway is involved in the OSM-induced proliferation. Treatment with OSM also induced phosphorylation of JAK2 and JAK3, and pretreatment of the cells with WHI-P131, a JAK3 inhibitor, but not with AG490, a JAK2 inhibitor, attenuated the OSM-induced proliferation of hATSCs. Furthermore, OSM treatment elicited phosphorylation of STAT1 and STAT3, and pretreatment with WHI-P131 specifically prevented the OSM-induced phosphorylation of STAT1, without affecting the OSM-induced phosphorylation of ERK and STAT3. These results suggest that two separate signaling pathways, such as MEK/ERK and JAK3/STAT1, are independently involved in the OSM-stimulated proliferation of hATSCs.     

Biophysical cues enhance myogenesis of human adipose derived stem/stromal cells

Adipose-derived stem/stromal cell (ASC)-based tissue engineered muscle grafts could provide an effective alternative therapy to autografts – which are limited by their availability – for the regeneration of damaged muscle. However, the current myogenic potential of ASCs is limited by their low differentiation efficiency into myoblasts. The aim of this study was to enhance the myogenic response of human ASCs to biochemical cues by providing biophysical stimuli (11% cyclic uniaxial strain, 0.5 Hz, 1 h/day) to mimic the cues present in the native muscle microenvironment. ASCs elongated and fused upon induction with myogenic induction medium alone. Yet, their myogenic characteristics were significantly enhanced with the addition of biophysical stimulation; the nuclei per cell increased approximately 4.5-fold by day 21 in dynamic compared to static conditions (23.3 ± 7.3 vs. 5.2 ± 1.6, respectively), they aligned at almost 45° to the direction of strain, and exhibited significantly higher expression of myogenic proteins (desmin, myoD and myosin heavy chain). These results demonstrate that mimicking the biophysical cues inherent to the native muscle microenvironment in monolayer ASC cultures significantly improves their differentiation along the myogenic lineage.     

Functional studies of mesenchymal stem cells derived from adult human adipose tissue

Recent evidence suggests that cells with the properties of human mesenchymal stem cells (hMSCs) can be derived from adult peripheral tissues, including adipose tissue, muscle and dermis. We isolated hMSCs from the stromal-vascular portion of subcutaneous adipose tissue from seven adult subjects. These cells could be readily differentiated into cells of the chondrocyte, osteocyte and adipocyte lineage demonstrating their multipotency. We studied the functional properties of hMSCs-derived adipocytes and compared them with adipocytes differentiated from hMSCs obtained from bone marrow (BM-hMSC). The two cell types displayed similar lipolytic capacity upon stimulation with catecholamines, including a pronounced antilipolytic effect mediated through alpha2A-adrenoceptors, a typical trait in human but not rodent fat cells. Furthermore, both cell types secreted the fat cell-specific factors leptin and adiponectin in comparable amounts per time unit. The fat tissue-derived hMSCs retained their differentiation capacity up to at least fifteen passages. We conclude that hMSCs derived from adult human adipose tissue can be differentiated into fully functional adipocytes with a similar, if not identical, phenotype as that observed in cells derived from BM-hMSCs. Human adipose-tissue-derived MSCs could therefore constitute an efficient and easily obtainable renewable cellular source for studies of adipocyte biology.     

Nuclear structure and gene activity in human differentiated cells

The nuclear arrangement of the ABL, c-MYC, and RB1 genes was quantitatively investigated in human undifferentiated HL-60 cells and in a terminally differentiated population of human granulocytes. The ABL gene was expressed in both cell types, the c-MYC gene was active in HL-60 cells and down-regulated in granulocytes, and expression of the RB1 gene was undetectable in HL-60 cells but up-regulated in granulocytes. The distances of these genes to the nuclear center (membrane), to the center of the corresponding chromosome territory, and to the nearest centromere were determined. During granulopoesis, the majority of selected genetic structures were repositioned closer to the nuclear periphery. The nuclear reposition of the genes studied did not correlate with the changes of their expression. In both cell types, the c-MYC and RB1 genes were located at the periphery of the chromosome territories regardless of their activity. The centromeres of chromosomes 8 and 13 were always positioned more centrally within the chromosome territory than the studied genes. Close spatial proximity of the c-MYC and RB1 genes with centromeric heterochromatin, forming the chromocenters, correlated with gene activity, although the nearest chromocenter of the silenced RB1 gene did not involve centromeric heterochromatin of chromosome 13 where the given gene is localized. In addition, the role of heterochromatin in gene silencing was studied in retinoblastoma cells. In these differentiated tumor cells, one copy of the RB1 gene was positioned near the heterochromatic chromosome X, and reduced RB1 gene activity was observed. In the experiments presented here, we provide evidence that the regulation of gene activity during important cellular processes such as differentiation or carcinogenesis may be realized through heterochromatin-mediated gene silencing.     

脂肪组织源性干细胞研究进展

增加具有完整功能的种子细胞数目是细胞移植的首要环节。近来研究发现,成体动物脂肪组织中含有大量的具有多向分化潜能的间充质干细胞,在特定条件下可分化为多种组织细胞,如脂肪细胞、成骨细胞、软骨细胞、肌细胞及神经星状细胞等,且具有极强的自我复制能力,有望成为组织工程理想的种子细胞。本文综述了脂肪组织源性干细胞（ADSCs）的发现、生物学特性、多向分化潜能、应用前景及存在的问题。     

Adipogenic potential of human adipose derived stromal cells from multiple donors is heterogeneous

The current study was done to assess if heterogeneity existed in the degree of adipogenesis in stromal cells (preadipocytes) from multiple donors. In addition to conventional lipid-based methods, we have employed a novel signal amplification technology, known as branched DNA, to monitor expression of an adipocyte specific gene product aP2. The fatty acid binding protein aP2 increases during adipocyte differentiation and is induced by thiazolidinediones and other peroxisome proliferator activated receptor gamma ligands. The current work examined the adipogenic induction of aP2 mRNA levels in human adipose tissue stromal cells derived from 12 patients (mean age +/- SEM, 38.9 +/- 3.1) with mild to moderate obesity (mean body mass index +/- SEM, 27.8 +/- 2.4). Based on branched DNA technology, a rapid and sensitive measure of specific RNAs, the relative aP2 level in adipocytes increased by 679 +/- 93-fold (mean +/- SEM, n=12) compared to preadipocytes. Normalization of the aP2 mRNA levels to the housekeeping gene, glyceraldehyde phosphate dehydrogenase, did not significantly alter the fold induction in a subset of 4 patients (803.6 +/- 197.5 vs 1118.5 +/- 308.1). Independent adipocyte differentiation markers were compared between adipocytes and preadipocytes in parallel studies. Leptin secretion increased by up to three-orders of magnitude while measurements of neutral lipid accumulation by Oil Red O and Nile Red staining increased by 8.5-fold and 8.3-fold, respectively. These results indicate that preadipocytes isolated from multiple donors displayed varying degrees of differentiation in response to an optimal adipogenic stimulus in vitro. This work also demonstrates that branched DNA measurement of aP2 is a rapid and sensitive measure of adipogenesis in human stromal cells. The linear range of this assay extends up to three-orders of magnitude and correlates directly with independent measures of cellular differentiation.     

Differentiation of human adipose derived stem cells into Leydig‐like cells with molecular compounds

Leydig cells (LCs) are the primary source of testosterone in the testis, and testosterone deficiency caused by LC functional degeneration can lead to male reproductive dysfunction. LC replacement transplantation is a very promising approach for this disease therapy. Here, we report that human adipose derived stem cells (ADSCs) can be differentiated into Leydig‐like cells using a novel differentiation method based on molecular compounds. The isolated human ADSCs expressed positive CD29, CD44, CD59 and CD105, negative CD34, CD45 and HLA‐DR using flow cytometry, and had the capacity of adipogenic and osteogenic differentiation. ADSCs derived Leydig‐like cells (ADSC‐LCs) acquired testosterone synthesis capabilities, and positively expressed LC lineage‐specific markers LHCGR, STAR, SCARB1, SF‐1, CYP11A1, CYP17A1, HSD3B1 and HSD17B3 as well as negatively expressed ADSC specific markers CD29, CD44, CD59 and CD105. When ADSC‐LCs labelled with lipophilic red dye (PKH26) were injected into rat testes which were selectively eliminated endogenous LCs using ethylene dimethanesulfonate (EDS, 75 mg/kg), the transplanted ADSC‐LCs could survive and function in the interstitium of testes, and accelerate the recovery of blood testosterone levels and testis weights. These results demonstrated that ADSCs could be differentiated into Leydig‐like cells by few defined molecular compounds, which might lay the foundation for further clinical application of ADSC‐LC transplantation therapy.     

Effect of T3 hormone on neural differentiation of human adipose derived stem cells

Human adult stem cells, which are capable of self‐renewal and differentiation into other cell types, can be isolated from various tissues. There are no ethical and rejection problems as in the case of embryonic stem cells, so they are a promising source for cell therapy. The human body contains a great amount of adipose tissue that contains high numbers of mesenchymal stem cells. Human adipose‐derived stem cells (hADSCs) could be easily induced to form neuron‐like cells, and because of its availability and abundance, we can use it for clinical cell therapy. On the other hand, T₃ hormone as a known neurotropic factor has important impressions on the nervous system. The aim of this study was to explore the effects of T₃ treatment on neural differentiation of hADSCs. ADSCs were harvested from human adipose tissue, after neurosphere formation, and during final differentiation, treatment with T₃ was performed. Immunocytochemistry, real‐time RT‐PCR, Western blotting techniques were used for detection of nestin, MAP2, and GFAP markers in order to confirm the effects of T₃ on neural differentiation of hADSCs. Our results showed an increase in the number of glial cells but reduction in neuronal cells number fallowing T₃ treatment. Copyright © 2014 John Wiley & Sons, Ltd.     

Functional expression of adrenoreceptors in mesenchymal stromal cells derived from the human adipose tissue

Cultured mesenchymal stromal cells (MSCs) from different sources represent a heterogeneous population of proliferating non-differentiated cells that contains multipotent stem cells capable of originating a variety of mesenchymal cell lineages. Despite tremendous progress in MSC biology spurred by their therapeutic potential, current knowledge on receptor and signaling systems of MSCs is mediocre. Here we isolated MSCs from the human adipose tissue and assayed their responsivity to GPCR agonists with Ca^2 + imaging. As a whole, a MSC population exhibited functional heterogeneity. Although a variety of first messengers was capable of stimulating Ca²⁺ signaling in MSCs, only a relatively small group of cells was specifically responsive to the particular GPCR agonist, including noradrenaline. RT-PCR and immunocytochemistry revealed expression of α1B-, α2A-, and β2-adrenoreceptors in MSCs. Their sensitivity to subtype-specific adrenergic agonists/antagonists and certain inhibitors of Ca²⁺ signaling indicated that largely the α2A-isoform coupled to PLC endowed MSCs with sensitivity to noradrenaline. The all-or-nothing dose-dependence was characteristic of responsivity of robust adrenergic MSCs. Noradrenaline never elicited small or intermediate responses but initiated large and quite similar Ca²⁺ transients at all concentrations above the threshold. The inhibitory analysis and Ca²⁺ uncaging implicated Ca²⁺-induced Ca²⁺ release (CICR) in shaping Ca²⁺ signals elicited by noradrenaline. Evidence favored IP₃ receptors as predominantly responsible for CICR. Based on the overall findings, we inferred that adrenergic transduction in MSCs includes two fundamentally different stages: noradrenaline initially triggers a local and relatively small Ca²⁺ signal, which next stimulates CICR, thereby being converted into a global Ca²⁺ signal.     

Proteomic analysis of human mesenchymal stromal cells derived from adipose tissue undergoing osteoblast differentiation

Background aimsStem cells derived from human adipose tissue (ASC) have the capacity for renewal, are easily obtained and have plasticity properties that allow them to differentiate into several cell types, including osteoblast cells. With the aim of understanding the issue of the osteogenic process and finding reliable biomarkers in cells undergoing the osteogeneic differentiation process, this work took advantage of a proteomic approach to identify proteins involved in osteogenesis.MethodsFor this purpose, ASC were analyzed under three conditions: S0, in the absence of stimulation; S1, with 2 weeks of osteogenic medium stimulation; and S2, with 4 weeks of osteogenic medium stimulation. The identification of ASC was carried out by flow cytometry using antibodies specific to known undifferentiated stem cell-surface markers. Cell viability, enzymatic activity, mineral deposition, collagen structure and production and gene analyzes were evaluated for each condition.ResultsPhenotypic modifications were observed during the in vitro osteogenic differentiation process by two-dimensional (2-D) differential image gel electrophoresis (DIGE). The proteins were identified by mass espectrometry in tandem (MS/MS) analyzes using Matrix-assisted laser desorption/ionization with TOF/TOF is a tandem mass spectrometry method where two time-of-flight mass spectrometers are used consecutively (MALDI-TOF/TOF). A total of 51 differentially expressed proteins was identified when comparing the three observed conditions. Sixteen different spots were identified in the S0 stage compared with S2, while 28 different spots were found in S2 compared with S0. S1 expressed seven different spots compared with S0 and S2.ConclusionsThese findings suggest the involvement of several proteins directly related to the osteogenic pathway, which can be used to improve understanding of the osteogenic process.     

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.     

Sphingosylphosphorylcholine induces proliferation of human adipose tissue-derived mesenchymal stem cells via activation of JNK

Sphingosylphosphorylcholine (SPC) has been implicated in a variety of cellular responses, including proliferation and differentiation. In this study, we demonstrate that d-erythro-SPC, but not l-threo-SPC, stereoselectively stimulated the proliferation of human adipose tissue-derived mesenchymal stem cells (hADSCs), with a maximal increase at 5 microM, and increased the intracellular concentration of Ca(2+) ([Ca(2+)](i)) in hADSCs, which do not express known SPC receptors (i.e., OGR1, GPR4, G2A, and GPR12). The SPC-induced proliferation and increase in [Ca(2+)](i) were sensitive to pertussis toxin (PTX) and the phospholipase C (PLC) inhibitor U73122, suggesting that PTX-sensitive G proteins, Gi or Go, and PLC are involved in SPC-induced proliferation. In addition, SPC treatment induced the phosphorylation of c-Jun and extracellular signal-regulated kinase, and SPC-induced proliferation was completely prevented by pretreatment with the c-Jun N-terminal kinase (JNK)-specific inhibitor SP600125 but not with the MEK-specific inhibitor U0126. Furthermore, the SPC-induced proliferation and JNK activation were completely attenuated by overexpression of a dominant negative mutant of JNK2, and the SPC-induced activation of JNK was inhibited by pretreatment with PTX or U73122. Treatment of hADSCs with lysophosphatidic acid (LPA) receptor antagonist, Ki16425, had no impact on the SPC-induced increase in [Ca(2+)](i). However, SPC-induced proliferation was partially, but significantly, attenuated by pretreatment of the cells with Ki16425.These results indicate that SPC stimulates the proliferation of hADSCs through the Gi/Go-PLC-JNK pathway and that LPA receptors may be responsible in part for the SPC-induced proliferation.     

Observatons on the growth and metabolic functions of cultured cells derived from human adipose tissue.

The growth and metabolic activity of cultured cells derived from human adipose tissue (CAT cells) were studied and compared to cultured skin fibroblasts. The morphological appearance of the CAT cells was distinctly different from that of fibroblasts. The growth rate of CAT cells as measured by 3H-thymidine incorporation was much slower than the fibroblast growth rate. Cultured CAT cells synthesized significantly 14C-glucose, while fibroblast cultures had a higher metabolic rate as measured by CO2 production. Insulin stimulated 3H-thymidine incorporation in both CAT and fibroblast cultures. The CAT cells did not show a consistent insulin response of lipid or CO2 production, but this may be a reflection of donor age or nutritional status. Even though the CAT cell may be a type of stromal cell peculiar to adipose tissue rather than a preadipocyte or adipocyte, it may prove useful in studies of human obesity.