Th17 immune response to adipose tissue-derived mesenchymal stromal cells

Adipose tissue-derived mesenchymal stromal cells (ASCs) hold the promise of achieving successful immunotherapeutic results due to their ability to regulate different T-cell fate. ASCs also show significant adaptability to environmental stresses by modulating their immunologic profile. Cell-based therapy for inflammatory diseases requires a detailed understanding of the molecular relation between ASCs and Th17 lymphocytes taking into account the influence of inflammation and cell ratio on such interaction. Accordingly, a dose-dependent increase in Th17 generation was only observed in high MSC:T-cell ratio with no significant impact of inflammatory priming. IL-23 receptor (IL-23R) expression by T cells was not modulated by ASCs when compared to levels in activated T cells, while ROR-γt expression was significantly increased reaching a maximum in high (1:5) unprimed ASC:T-cell ratio. Finally, multiplex immunoassay showed substantial changes in the secretory profile of 15 cytokines involved in the Th17 immune response (IL-1β, IL-4, IL-6, IL-10, IL-17A, IL-17F, IL-22, IL-21, IL-23, IL-25, IL-31, IL-33, IFN-γ, sCD40, and TNF-α), which was modulated by both cell ratio and inflammatory priming. These findings suggest that Th17 lymphocyte pathway is significantly modulated by ASCs that may lead to immunological changes. Therefore, future ASC-based immunotherapy should take into account the complex and detailed molecular interactions that depend on several factors including inflammatory priming and cell ratio.     

Culture expansion induces non-tumorigenic aneuploidy in adipose tissue-derived mesenchymal stromal cells

Background aimsAdipose tissue-derived mesenchymal stromal cells (ASCs) are of interest as a cell therapeutic agent for immunologic and degenerative diseases. During in vitro expansion, ASCs may be at risk for genetic alterations, and genetic screening is a prerequisite. We examined the presence of aneuploidy in ASCs and its origin and development during culture and evaluated the implications of aneuploidy for therapeutic use of ASCs.MethodsAdipose tissue of healthy individuals was used for isolation and expansion of ASCs. Chromosome copy numbers were studied using fluorescence in situ hybridization analysis. Aneuploidy was studied in freshly isolated ASCs, in ASCs cultured for 0–16 passages and in senescent cultures. To evaluate the plasticity of ploidy, ASCs were cloned, and the variation of ploidy in the clones was examined. Tumorigenicity was studied by subcutaneous injection of aneuploid ASCs in immunodeficient NOD/SCID mice.ResultsNo aneuploidy was detected in freshly isolated ASCs. In low passages (passages 0–4), aneuploidy was detected in 3.4% of ASCs. Prolonged culture expansion of ASCs (passages 5–16) resulted in a significant increase of aneuploidy to 7.1%. With senescence, aneuploidy increased further to 19.8%. Aneuploidy was observed in clones of diploid ASCs, demonstrating the de novo development of aneuploidy. No transformation of ASCs was observed, and in contrast to cancer cell lines, aneuploid ASCs were incapable of tumor formation in immunodeficient mice.ConclusionsASC cultures contain a stable percentage of aneuploid cells. Aneuploidy was not a predecessor of transformation or tumor formation. This finding indicates that aneuploidy is culture-induced but unlikely to compromise clinical application of ASCs.     

A non-enzymatic method for isolating human adipose tissue-derived stromal stem cells

Background aimsThe isolation of human adipose stromal/stem cells (ASCs) currently relies on the use of the enzyme collagenase, which digests the triple helix region of peptide bonds in the collagen of adipose tissue. Collagenase is an expensive reagent derived from a bacterial source, and its use in isolating ASCs is a time-consuming procedure. This experiment evaluated the extraction of ASCs without an enzymatic digest.MethodsWe used a simple method of washing adipose tissue to isolate and characterize the cells and compared this method with the enzymatic procedure in terms of processing time, stem cell yield, differentiation potential and immunophenotype.ResultsBased on fluorescence activated cell sorting analysis, the stromal vascular fractions isolated with the washing method displayed a distinct and potentially favorable immunophenotype relative to the collagenase digestion. This difference may reflect the absence of chemical alteration of the cells by collagenase digestion. Independent of the isolation procedure, the resulting passaged ASCs were comparable based on immunophenotype and adipogenic and osteogenic differentiation potential.ConclusionsAlthough using collagenase substantially increases cell yield, the two methods yield a similar cell product.     

Hydrolyzed fish collagen induced chondrogenic differentiation of equine adipose tissue-derived stromal cells

Adipose-derived stromal cells (ADSCs) are multipotent cells which, in the presence of appropriate stimuli, can differentiate into various lineages such as the osteogenic, adipogenic and chondrogenic. In this study, we investigated the effect of transforming growth factor beta 1 (TGF-β1) in comparison to hydrolyzed fish collagen in terms of the chondrogenic differentiation potential of ADSCs. ADSCs were isolated from subcutaneous fat of horses by liposuction. Chondrogenesis was investigated using a pellet culture system. The differentiation medium was either supplemented with TGF-β1 (5 ng/ml) or fish collagen (0.5 mg/ml) for a 3 week period. After the 3 weeks in vitro differentiation, RT-PCR and histological staining for proteoglycan synthesis and type II collagen were performed to evaluate the degree of chondrogenic differentiation and the formation of cartilaginous extracellular matrix (ECM). The differentiation of ADSCs induced by TGF-β1 showed a high expression of glycosaminoglycan (GAG). Histological analysis of cultures stimulated by hydrolyzed fish collagen demonstrated an even higher GAG expression than cultures stimulated under standard conditions by TGF-β1. The expression of cartilage-specific type II collagen and Sox9 was about the same in both stimulated cultures. In this study, chondrogenesis was as effectively induced by hydrolyzed fish collagen as it was successfully induced by TGF-β1. These findings demonstrated that hydrolyzed fish collagen alone has the potential to induce and maintain ADSCs-derived chondrogenesis. These results support the application of ADSCs in equine veterinary tissue engineering, especially for cartilage repair.     

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.     

Impaired immunomodulatory capacity in adipose tissue-derived mesenchymal stem/stromal cells isolated from obese patients

Immune-modulatory properties of adipose tissue-derived mesenchymal stem/stromal cells (MSCs) might be susceptible to metabolic disturbances. We hypothesized that the immune-modulatory function of MSCs might be blunted in obese human subjects. MSCs were collected from abdominal subcutaneous fat of obese and lean subjects during bariatric or kidney donation surgeries, respectively. MSCs were co-cultured in vitro for 24 h with M1 macrophages, which were determined as M1or M2 phenotypes by flow cytometry, and cytokines measured in conditioned media. In vivo, lean or obese MSCs (5 × 10⁵), or PBS, were injected into mice two weeks after unilateral renal artery stenosis (RAS) or sham surgeries (n = 6 each). Fourteen days later, kidneys were harvested and stained with M1 or M2 markers. Lean MSCs decreased macrophages M1 marker intensity, which remained elevated in macrophages co-cultured with obese MSCs. TNF-α levels were four-fold higher in conditioned media collected from obese than from lean MSCs. RAS mouse kidneys were shrunk and showed increased M1 macrophage numbers and inflammatory cytokine expression compared with normal kidneys. Lean MSCs decreased M1 macrophages, M1/M2 ratio and inflammation in RAS kidneys, whereas obese MSCs did not. MSCs isolated from lean human subjects decrease inflammatory M1 macrophages both in vivo and in vitro, an immune-modulatory function which is blunted in MSCs isolated from obese subjects.     

Pleiotropic effects on proliferation and mineralization of primary human adipose tissue-derived stromal cells induced by simvastatin

The circulating low-density lipoprotein concentration in blood can be reduced by the administration of statins. Frequently simvastatin (SV) is prescribed. Due to the reported pleiotropic effects of SV the aim of this study was to evaluate mineralization effects on human adipose tissue-derived stromal cells upon administration of SV. After informed consent human adipose tissue-derived stromal cells were obtained from tissue surplus of regular treatments of 14 individuals. According to established protocols after adding various SV concentrations (0.01 µM, 0.1 µM, 1.0 µM, 2.0 µM), alkaline phosphate (osteoblastic marker), mineralization capability and viability were determined at day 18, 21 and 28. The Kruskal–Wallis test was performed for statistical analysis. After adding SV a dose-dependent significant decreased viability and levels of alkaline phosphatase (p < 0.01) and a significantly increased mineralization (p < 0.01) of the primary cultures was recognized during the late mineralization stage. Mineralization of the human adipose tissue-derived stromal cells was induced by SV, possibly originated from alternative pathways than the alkaline phosphatase pathway. Further investigations should be performed regarding switching into the osteoblastic differentiation and as a possible source of cells that can be used as the basis for a potential bone graft substitute, which may allow an extension of the field of application.     

Surface protein expression between human adipose tissue-derived stromal cells and mature adipocytes

Adipose tissue contains a stroma that can be easily isolated. Thus, human adipose tissue presents an source of multipotent stromal cells. In order to determine the implication of hematopoietic markers in adipocyte biology, we have defined part of the phenotype of the human adipose tissue-derived stromal cells, and compared this to fully differentiated adipocytes. Flow cytometry demonstrates that the protein expression phenotype of both cell types are similar and includes the expression of CD10, CD13, CD34, CD36, CD55, CD59 and CD65. No significant difference between subcutaneous and omental adipose tissue could be demonstrated concerning the expression of these markers. However, the expression of CD34, CD36 and CD65 is cell-dependent. While the expression of CD36 and CD65 doubled between stromal cells and mature adipocytes, the expression of CD34 decreased, despite this protein being present on the mature adipocyte. As CD34 is described as a stem cell marker and it being unlikely to be expressed on differentiated cells, this result was confirmed by immunostaining and western blot. The clear function of this protein on the adipocyte membrane remains to be determined. The characterization of new proteins on mature adipocytes could have broad implications for the comprehension of the biology of this tissue.     

Insulin-producing cells from human adipose tissue-derived mesenchymal stem cells detected by atomic force microscope

We successfully differentiated human adipose tissue-derived mesenchymal stem cells (haMSCs) into insulin-producing cells (IPCs) in vitro and did not use any insulin which might be absorbed by cells during in vitro culture. Expression of insulin gene was massively increased by 28,000-fold at day 12 compared with haMSCs (P < 0.05). IPCs could secrete insulin after glucose was stimulated. The higher the concentration of glucose, the more production of insulin was noted. We reported AFM images of IPCs for the first time. AFM images showed that the sizes of cells were similar to each other, and all IPC surface had a porous structure in the cytoplasm area. In sugar-free group, the size of holes was similar (diameter, 1,086.98 ± 156.70 nm; depth, 185.22 ± 52.14 nm). In higher sugar-stimulated group, there were more holes with bigger diameter and smaller depth. (diameter, 3,183.65 ± 2,229.18 nm; depth 109.42 ± 56.26 nm, P < 0.05). We found that the hole diameter and depth could change with the concentration of glucose in media. Concurrently, laser scanning confocal microscopy images indicated that cortical actin network beneath plasma membrane in IPCs was dense and continuous. After glucose stimulation, we found the actin web depolymerized and became discontinuous in IPCs. We speculated that diameter augmentation of holes located in the cytoplasm area in IPCs was one manifestation of excytosis increase.     

Autologous rabbit adipose tissue-derived mesenchymal stromal cells for the treatment of bone injuries with distraction osteogenesis

Background aimsAdipose tissue-derived mesenchymal stromal cells (MSCs) have a higher capacity for proliferation and differentiation compared with other cell lineages. Although distraction osteogenesis is the most important therapy for treating bone defects, this treatment is restricted in many situations. The aim of this study was to examine the therapeutic potential of adipose tissue-derived MSCs and osteoblasts differentiated from adipose tissue-derived MSCs in the treatment of bone defects.MethodsBone defects were produced in the tibias of New Zealand rabbits that had previously undergone adipose tissue extraction. Tibial osteotomy was performed, and a distractor was placed on the right leg of the rabbits. The rabbits were placed in control (group I), stem cell (group II) and osteoblast-differentiated stem cell (group III) treatment groups. The rabbits were sacrificed, and the defect area was evaluated by radiologic, biomechanical and histopathologic tests to examine the therapeutic effects of adipose tissue-derived MSCs.ResultsRadiologic analyses revealed that callus density and the ossification rate increased in group III compared with group I and group II. In biomechanical tests, the highest ossification rate was observed in group III. Histopathologic studies showed that the quality of newly formed bone and the number of cells active in bone formation were significantly higher in group III rabbits compared with group I and group II rabbits.ConclusionsThese data reveal that osteoblasts differentiated from adipose tissue-derived MSCs shorten the consolidation period of distraction osteogenesis. Stem cells could be used as an effective treatment for bone defects.     

Serum-free non-toxic freezing solution for cryopreservation of human adipose tissue-derived mesenchymal stem cells

Objective

To develop a cost-effective, non-toxic and xeno-free freezing solution for the preservation of adipose tissue-derived stem cells (hADSC) with a long shelf-life.

Results

The potential of various hydrocolloids and organic osmolytes as cryoprotectants and individual components of phosphate buffered saline (PBS) as carrier media were evaluated to formulate a freezing solution for the cryopreservation of hADSCs. Among the hydrocolloids, the highest viability, 55 %, was achieved with post-thawed (after 48 h storage at ?80 °C) hADSCs cryopreserved in 10 % (v/v) polyvinylpyrrolidone (PVP) using PBS as carrier media. 0.9 % NaCl was a superior carrier medium resulting an enhanced cell viability (70 %) when used in 10 % PVP than other components of PBS. A higher cell viability (81 %) was achieved when 10 % PVP/0.9 % NaCl was supplemented with 60 mM ectoin. The cryopreserved cells retained normal cytoskeletal distribution pattern and adipogenic and osteogenic differentiation ability during 14 and 21 days of incubation.

Conclusion

A serum-free and non-toxic 10 % PVP/0.9 % NaCl/60 mM ectoin freezing solution was developed for cryopreservation of hADSC for application in tissue engineering and regenerative medicine.

     

Wedelolactone inhibits adipogenesis through the ERK pathway in human adipose tissue-derived mesenchymal stem cells

Wedelolactone is an herbal medicine that is used to treat septic shock, hepatitis and venom poisoning. Although in differentiated and cancer cells, wedelolactone has been identified as anti‐inflammatory, growth inhibitory, and pro‐apoptotic, the effects of wedelolactone on stem cell differentiation remain largely unknown. Here, we report that wedelolactone inhibits the adipogenic differentiation of human adipose tissue‐derived mesenchymal stem cells (hAMSCs). Wedelolactone reduced the formation of lipid droplets and the expression of adipogenesis‐related proteins, such as CCAAT enhancer‐binding protein‐α (C/EBP‐α), peroxisome proliferator‐activated receptor‐γ (PPAR‐γ), lipoprotein lipase (LPL), and adipocyte fatty acid‐binding protein aP2 (aP2). Wedelolactone mediated this process by sustaining ERK activity. In addition, inhibition of ERK activity with PD98059 resulted in reversion of the wedelolactone‐mediated inhibition of adipogenic differentiation. Taken together, these results indicate that wedelolactone inhibits adipogenic differentiation through ERK pathway and suggest a novel inhibitory effect of wedelolactone on adipogenic differentiation in hAMSCs. J. Cell. Biochem. 113: 3436–3445, 2012. © 2012 Wiley Periodicals, Inc.     

Hypoxia enhances chondrogenic differentiation of human adipose tissue-derived stromal cells in scaffold-free and scaffold systems

Human adipose-derived stromal cells (hASCs) possess the potential for chondrogenic differentiation. Recent studies imply that this differentiation process may be enhanced by culturing the cells in low oxygen tension in combination with three-dimensional (3D) scaffolds. We report the evaluation of the chondrogenic potential of hASC pellets in 5 and 21 % O₂ and as cell-scaffold constructs using a collagen I/III scaffold with chemical induction using TGF-β3. hASCs from four human donors were cultured both in a micromass pellet system and in 3D collagen I/III scaffolds in either 5 or 21 % O₂. Chondrogenesis was evaluated by quantitative gene expression analysis of aggrecan, SOX9, collagen I, II and X and histological evaluation with H&E and toluidine blue staining. Induced pellets cultured in 5 % O₂ showed increased peripheral cellularity and matrix deposition compared with 21 % O₂. Induced pellets cultured in 5 % O₂ had increased control-adjusted gene expression of aggrecan, SOX9 and collagen I and decreased collagen X compared with 21 % O₂ cultures. Induced pellets had higher gene expression of aggrecan, SOX9, collagen I, II and X and increased ratios of collagen II/I and collagen II/X compared with controls. As for pellets, scaffold cultures showed cellularity and matrix deposition organized in a zonal manner as a function of the oxygen tension, with a cartilage-like morphology and matrix deposition peripherally in the 5 % O₂ group and a more centrally located matrix in the 21 % O₂ group. There were no differences in histology and gene expressions between pellet and scaffold cultures. Five percent O₂ in combination with chondrogenic culture medium stimulated chondrogenic differentiation of hASCs in vitro. We observed similar patterns of differentiation and matrix disposition in pellet and scaffold cultures.     

Expression of telomerase extends longevity and enhances differentiation in human adipose tissue-derived stromal cells.

Human bone marrow stromal cells (hBMSCs) are defined as pluripotent progenitor cells with the ability to differentiate into osteoblasts, chondrochytes, adipocytes, muscle cells, and neural cells. Recently, it has been shown that telomerase expression not only extends the replicative life-span and maintains their bone-forming capability of hBMSCs. We previously reported that human adipose tissue stromal cells (hATSCs) have similar characteristics with hBMSCs. In this study, hATSCs were stably tranduced by a retrovirus containing the gene for the catalytic subunit of human telomerase (hTERT) and MSCV-neo retrovirus, and 12 clones for hTERT-hATSCs and 6 clones for MSCV-hATSCs were isolated. The tranduced clones (hATSC-TERTs) had high telomerase activity, which was maintained during subsequent subcultivation. The transduced cells of two representative clones have undergone more than 100 population doublings (PD) and continue to proliferate, whereas control cells underwent senescence-associated proliferation arrest after 36-40 PD. The cells had a normal karyotype, and increased differentiation potential, especially osteogenic lineage. Intraventricular injection of hATSC-TERTs in ischemic rat brain showed enhancement of functional recovery as like hATSC-MSCVs. The tissue engraftment of hATSCs and hTERT-hATSCs in NOD/SCID mice after intravenous administration was identical. These results further support a similarity between hBMSCs and hATSCs. hATSCs can be used as an alternative of pluripotent stromal cells for cell replacement therapy as like hBMSCs.     

Role of MEK-ERK pathway in sphingosylphosphorylcholine-induced cell death in human adipose tissue-derived mesenchymal stem cells

Sphingosylphosphorylcholine (SPC) is a bioactive lipid molecule involved in a variety of cellular responses. In the present study, we demonstrated that treatment of human adipose tissue-derived mesenchymal stem cells (hATSCs) with D-erythro-SPC resulted in apoptosis-like cell death, as demonstrated by decreased cell viability, DNA strand breaks, the increase of sub-G1 fraction, cytochrome c release into cytosol, and activation of caspase-3. In contrast, the exposure of hATSCs to L-threo-SPC did not induce the cell death, suggesting that the SPC-induced cell death was selective for the D-erythro-stereoisomer of SPC. The D-erythro-SPC-induced cell death was prevented by DEVD-CHO, a caspase-3 specific inhibitor, and Z-VAD-FMK, a general caspase inhibitor, suggesting that the SPC-induced cell death of hATSCs occurs through the cytochrome c- and caspase-3-dependent pathways. In addition, D-erythro-SPC treatment stimulated the activation of mitogen-activated protein kinases, such as ERK and c-Jun NH2-terminal protein kinase (JNK), and the D-erythro-SPC-induced cell death was completely prevented by pretreatment with the MEK inhibitor, U0126, but not by pretreatment with the JNK inhibitor, SP600125, and the p38 MAPK inhibitor, SB202190, suggesting a specific involvement of ERK in the D-erythro-SPC-induced cell death. Pretreatment with U0126 attenuated the D-erythro-SPC-induced release of cytochrome c. From these results, we suggest that ERK is involved in the SPC-induced cell death of hATSC through stimulation of the cytochrome c/caspase-3-dependent pathway.