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  • 1.
    Brohlin, Maria
    et al.
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Biomedical Laboratory Science.
    Kelk, Peyman
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Wiberg, Mikael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Kingham, Paul J.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Effects of a defined xeno-free medium on the growth and neurotrophic and angiogenic properties of human adult stem cells2017In: Cytotherapy, ISSN 1465-3249, E-ISSN 1477-2566, Vol. 19, no 5, p. 629-639Article in journal (Refereed)
    Abstract [en]

    Background. The growth properties and neurotrophic and angiogenic effects of human mesenchymal stromal cells (MSCs) cultured in a defined xeno-free, serum-free medium (MesenCult-XF) were investigated. Methods. Human MSCs from adipose tissue (ASCs) and bone marrow (BMSCs) were cultured in Minimum Essential Medium-alpha (alpha-MEM) containing fetal calf serum or in MesenCult-XF. Proliferation was measured over 10 passages and the colony-forming unit (CFU) assay and expression of cluster of differentiation (CD) surface markers were determined. Neurite outgrowth and angiogenic activity of the MSCs were determined. Results. At early passage, both ASCs and BMSCs showed better proliferation in MesenCult-XF compared with standard a-MEM containing serum. However, CFUs were significantly lower in MesenCult-XF. ASCs cultured in MesenCult-XF continued to expand at faster rates than cells grown in serum. BMSCs showed morphological changes at late passage in MesenCult-XF and stained positive for senescence beta-galactosidase activity. Expression levels of CD73 and CD90 were similar in both cell types under the various culture conditions but CD105 was significantly reduced at passage 10 in MesenCult-XF. In vitro stimulation of the cells enhanced the expression of brain derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF-A) and angiopoietin-1. Stimulated ASCs grown in MesenCult-XF evoked the longest neurite outgrowth in a neuron co-culture model. Stimulated BMSCs grown in MesenCult-XF produced the most extensive network of capillary-like tube structures in an in vitro angiogenesis assay. Conclusions. ASCs and BMSCs exhibit high levels of neurotrophic and angiogenic activity when grown in the defined serum free medium indicating their suitability for treatment of various neurological conditions. However, long-term expansion in MesenCult-XF might be restricted to ASCs.

  • 2.
    Chen, Jialin
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Zhang, Wei
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Backman, Ludvig J.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Kelk, Peyman
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Danielson, Patrik
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Mechanical stress potentiates the differentiation of periodontal ligament stem cells into keratocytes2018In: British Journal of Ophthalmology, ISSN 0007-1161, E-ISSN 1468-2079, Vol. 102, no 4, p. 562-569Article in journal (Refereed)
    Abstract [en]

    Aims To explore the role of corneal-shaped static mechanical strain on the differentiation of human periodontal ligament stem cells (PDLSCs) into keratocytes and the possible synergistic effects of mechanics and inducing medium. Methods PDLSCs were exposed to 3% static dome-shaped mechanical strain in a Flexcell Tension System for 3 days and 7 days. Keratocyte phenotype was determined by gene expression of keratocyte markers. Keratocyte differentiation (inducing) medium was introduced in the Flexcell system, either continuously or intermittently combined with mechanical stimulation. The synergistic effects of mechanics and inducing medium on keratocyte differentiation was evaluated by gene and protein expression of keratocyte markers. Finally, a multilamellar cell sheet was assembled by seeding PDLSCs on a collagen membrane and inducing keratocyte differentiation. The transparency of the cell sheet was assessed, and typical markers of native human corneal stroma were evaluated by immunofluorescence staining. Results Dome-shaped mechanical stimulation promoted PDLSCs to differentiate into keratocytes, as shown by the upregulation of ALDH3A1, CD34, LUM, COL I and COL V. The expression of integrins were also upregulated after mechanical stimulation, including integrin alpha 1, alpha 2, beta 1 and non-muscle myosin II B. A synergistic effect of mechanics and inducing medium was found on keratocyte differentiation. The cell sheets were assembled under the treatment of mechanics and inducing medium simultaneously. The cell sheets were transparent, multilamellar and expressed typical markers of corneal stroma. Conclusion Dome-shaped mechanical stimulation promotes differentiation of PDLSCs into keratocytes and has synergistic effects with inducing medium. Multilamellar cell sheets that resemble native human corneal stroma show potential for future clinical applications.

  • 3.
    Chen, Jialin
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Zhang, Wei
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Kelk, Peyman
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Backman, Ludvig J.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Community Medicine and Rehabilitation, Physiotherapy.
    Danielson, Patrik
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Clinical Sciences, Ophthalmology.
    Substance P and patterned silk biomaterial stimulate periodontal ligament stem cells to form corneal stroma in a bioengineered three-dimensional model2017In: Stem Cell Research & Therapy, E-ISSN 1757-6512, Vol. 8, article id 260Article in journal (Refereed)
    Abstract [en]

    Background: We aimed to generate a bioengineered multi-lamellar human corneal stroma tissue in vitro by differentiating periodontal ligament stem cells (PDLSCs) towards keratocytes on an aligned silk membrane.

    Methods: Human PDLSCs were isolated and identified. The neuropeptide substance P (SP) was added in keratocyte differentiation medium (KDM) to evaluate its effect on keratocyte differentiation of PDLSCs. PDLSCs were then seeded on patterned silk membrane and cultured with KDM and SP. Cell alignment was evaluated and the expression of extracellular matrix (ECM) components of corneal stroma was detected. Finally, multi-lamellar tissue was constructed in vitro by PDLSCs seeded on patterned silk membranes, which were stacked orthogonally and stimulated by KDM supplemented with SP for 18 days. Sections were prepared and subsequently stained with hematoxylin and eosin or antibodies for immunofluorescence observation of human corneal stroma-related proteins.

    Results: SP promoted the expression of corneal stroma-related collagens (collagen types I, III, V, and VI) during the differentiation induced by KDM. Patterned silk membrane guided cell alignment of PDLSCs, and important ECM components of the corneal stroma were shown to be deposited by the cells. The constructed multi-lamellar tissue was found to support cells growing between every two layers and expressing the main type of collagens (collagen types I and V) and proteoglycans (lumican and keratocan) of normal human corneal stroma.

    Conclusions: Multi-lamellar human corneal stroma-like tissue can be constructed successfully in vitro by PDLSCs seeded on orthogonally aligned, multi-layered silk membranes with SP supplementation, which shows potential for future corneal tissue engineering.

  • 4. Dinarello, Charles
    et al.
    Arend, William
    Sims, John
    Smith, Dirk
    Blumberg, Hal
    O'Neill, Luke
    Goldbach-Mansky, Raphaela
    Pizarro, Theresa
    Hoffman, H.
    Bufler, Philip
    Nold, Marcel
    Ghezzi, Pietro
    Mantovani, Alberto
    Garlanda, Cecilia
    Boraschi, Diana
    Rubartelli, Anna
    Netea, Mihai
    van der Meer, Jos
    Joosten, Leo
    Mandrup-Poulsen, Tom
    Donath, Marc
    Lewis, Eli
    Pfeilschifter, Josef
    Martin, Michael
    Kracht, Michael
    Muehl, H
    Novick, Daniela
    Lukic, Miodrag
    Conti, Bruno
    Solinger, Alan
    Kelk, Peyman
    Umeå University, Faculty of Medicine, Department of Odontology. Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    van de Veerdonk, Frank
    Gabel, Chiristopher
    IL-1 family nomenclature2010In: Nature Immunology, ISSN 1529-2908, E-ISSN 1529-2916, Vol. 11, no 11, p. 973-973Article in journal (Refereed)
  • 5.
    Höglund Åberg, Carola
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Kelk, Peyman
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology.
    Aggregatibacter actinomycetemcomitans: virulence of its leukotoxin and association with aggressive periodontitis2015In: Virulence, ISSN 2150-5608, Vol. 6, no 3, p. 188-195Article, review/survey (Refereed)
    Abstract [en]

    Periodontitis is an infection-induced inflammatory disease that causes loss of the tooth supporting tissues. Much focus has been put on comparison of the microbial biofilm in the healthy periodontium with the diseased one. The information arising from such studies is limited due to difficulties to compare the microbial composition in these two completely different ecological niches. A few longitudinal studies have contributed with information that makes it possible to predict which individuals who might have an increased risk of developing aggressive forms of periodontitis, and the predictors are either microbial or/and host-derived factors. The most conspicuous condition that is associated with disease risk is the presence of Aggregatibacter actinomycetemcomitans at the individual level. This Gram-negative bacterium has a great genetic variation with a number of virulence factors. In this review we focus in particular on the leukotoxin that, based on resent knowledge, might be one of the most important virulence factors of A. actinomycetemcomitans.

  • 6.
    Karalija, Amar
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Kelk, Peyman
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Wiberg, Mikael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Kingham, Paul J.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    The effects of acetyl-­L-­carnitine treatment on neuroinflammation: An in vitro studyManuscript (preprint) (Other academic)
  • 7.
    Kelk, Peyman
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Abd, H
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology.
    Sandström, G
    Sjöstedt, Anders
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology.
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology.
    Cellular and molecular response of human macrophages exposed to Aggregatibacter actinomycetemcomitans leukotoxin.2011In: Cell death & disease, ISSN 2041-4889, Vol. 2, p. e126-Article in journal (Refereed)
    Abstract [en]

    Aggregatibacter (Actinobacillus) actinomycetemcomitans is a facultative anaerobic gram-negative bacterium associated with severe forms of periodontitis. A leukotoxin, which belongs to the repeats-in-toxin family, is believed to be one of its virulence factors and to have an important role in the bacterium's pathogenicity. This toxin selectively kills human leukocytes by inducing apoptosis and lysis. Here, we report that leukotoxin-induced cell death of macrophages proceeded through a process that differs from the classical characteristics of apoptosis and necrosis. A. actinomycetemcomitans leukotoxin-induced several cellular and molecular mechanisms in human macrophages that led to a specific and excessive pro-inflammatory response with particular secretion of both interleukin (IL)-1β and IL-18. In addition, this pro-inflammatory cell death was inhibited by oxidized ATP, which indicates involvement of the purinergic receptor P2X(7) in this process. This novel virulence mechanism of the leukotoxin may have an important role in the pathogenic potential of this bacterium and can be a target for future therapeutic agents.

  • 8.
    Kelk, Peyman
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology, Periodontology. Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology.
    Abd, Hadi
    Centre for Microbiological Preparedness, Swedish Institute for Infectious Disease Control, Solna, Sweden.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology, Oral Microbiology.
    Sandström, Gunnar
    Centre for Microbiological Preparedness, Swedish Institute for Infectious Disease Control, Solna, Sweden ; Department of Laboratory Medicine, Division of Clinical Microbiology, Karolinska Institute, Stockholm, Sweden.
    Sjöstedt, Anders
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology.
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology, Periodontology.
    Inflammatory cell death of human macrophages in response to Aggregatibacter actinomycetemcomitans leukotoxinManuscript (Other academic)
    Abstract [en]

    Aggregatibacter (Actinobacillus) actinomycetemcomitans is a facultative anaerobic gram-negative bacterium associated with severe forms of periodontitis. A leukotoxin, which belongs to the Repeats in Toxin (RTX) family, is believed to be one of its virulence factors and to play an important role in the bacterium's pathogenicity. This toxin selectively kills human leukocytes by inducing apoptosis and lysis. Here we report that leukotoxin-induced cell death of macrophages proceeded through a process that differs from the classical characteristics of apoptosis and necrosis. Interestingly, this process resembled pyroptosis, and resulted in an extensive leukotoxin-induced interleukin-1β (IL-1β) secretion. This activation was mainly mediated by caspase-1 activation, while the levels of mRNA for IL-1β were not affected by the leukotoxin. A similar pattern was seen for IL-18, but the level of that cytokine was about 30 times lower. Both of these cytokines are synthesized as biologically inactive precursors and need active caspase-1 for their activation and secretion. In conclusion, A. actinomycetemcomitans leukotoxin induces a pyroptosis-like cell death in human macrophages and that leads to a specific and excessive pro-inflammatory response. This novel virulence mechanism of the leukotoxin may play an important role in the pathogenic potential of this bacterium.

  • 9.
    Kelk, Peyman
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology, Periodontology. Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology.
    Chen, Casey
    Sjöstedt, Anders
    Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Clinical Bacteriology.
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology. Parod.
    IL-1beta secretion induced by Aggregatibacter (Actinobacillus) actinomycetemcomitans is mainly caused by the leukotoxin2008In: International Journal of Medical Microbiology, ISSN 1438-4221, E-ISSN 1618-0607, Vol. 298, no 5/6, p. 529-541Article in journal (Refereed)
    Abstract [en]

    Aggregatibacter (Actinobacillus) actinomycetemcomitans forms a leukotoxin that selectively lyses primate neutrophils, monocytes and triggers apoptosis in promyeloic cells and degranulation of human neutrophils. Recently, we showed that the leukotoxin causes activation of caspase-1 and abundant secretion of bio-active IL-1beta from human macrophages. In this study, we show that high levels of IL-beta correlated with a high proportion of A. actinomycetemcomitans in clinical samples from a patient with aggressive periodontitis. To determine the relative contribution of leukotoxin to the overall bacteria-induced IL-1beta secretion, macrophages were isolated from peripheral blood and exposed to different concentrations of live A. actinomycetemcomitans strains with either no, low or high production of leukotoxin. Cell lysis and levels of IL-1beta, IL-6, TNF-alpha and caspase-1 were measured by ELISA and flow cytometry. Leukotoxin was the predominant cause of IL-1beta secretion from macrophages, even in the A. actinomycetemcomitans strain with low leukotoxin production. Macrophages exposed to non-leukotoxic bacteria accumulated cytosolic pro-IL-1beta, which was secreted by a secondary exposure to leukotoxic bacteria. In conclusion, the present study shows for the first time that A. actinomycetemcomitans-induced IL-1beta secretion from human macrophages in vitro is mainly caused by leukotoxin.

  • 10.
    Kelk, Peyman
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology, Periodontology.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology, Oral Microbiology.
    Hänström, L
    Umeå University, Faculty of Medicine, Department of Odontology, Periodontology.
    Lerner, Ulf
    Umeå University, Faculty of Medicine, Department of Odontology, Oral Cell Biology.
    Kalfas, S
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology, Periodontology.
    Abundant secretion of bioactive interleukin-1beta by human macrophages induced by Actinobacillus actinomycetemcomitans leukotoxin2005In: Infection and Immunity, ISSN 0019-9567, E-ISSN 1098-5522, Vol. 73, no 1, p. 453-458Article in journal (Refereed)
    Abstract [en]

    Actinobacillus actinomycetemcomitans produces a leukotoxin that selectively kills human leukocytes. Recently, we reported that macrophages are highly sensitive to leukotoxin and that their lysis involves activation of caspase 1. In this study, we show that leukotoxin also induces the production and release of proinflammatory cytokines from human macrophages. The macrophages were challenged with leukotoxin or lipopolysaccharide (LPS) from A. actinomycetemcomitans or LPS from Escherichia coli, and the production and secretion of interleukin-1beta (IL-1beta), IL-6, and tumor necrosis factor alpha (TNF-alpha) were determined at the mRNA and protein levels by reverse transcription-PCR and enzyme-linked immunosorbent assay, respectively. Leukotoxin (1 to 30 ng/ml) induced abundant production and secretion of IL-1beta, while the effects on IL-6 and TNF-alpha production were limited. Leukotoxin (1 ng/ml) caused a 10-times-higher release of IL-1beta than did LPS (100 ng/ml). The secreted IL-1beta was mainly the bioactive 17-kDa protein. At higher concentrations (>30 ng/ml), leukotoxin caused secretion of mainly inactive cytokine, the 31-kDa pro-IL-1beta. The presence of specific antibodies to IL-1beta or of a caspase 1 inhibitor blocked the secretion and production of the cytokine. Supernatants of leukotoxin-challenged macrophages stimulated bone resorption when tested in a mouse calvarial model. The activity could be blocked by an IL-1 receptor antagonist or specific antibodies to IL-1beta. We concluded that A. actinomycetemcomitans leukotoxin can trigger abundant production and secretion of bioactive IL-1beta by human macrophages, which is mediated by activation of caspase 1.

  • 11.
    Kelk, Peyman
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology, Periodontology.
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology, Periodontology.
    Claesson, Rolf
    Umeå University, Faculty of Medicine, Department of Odontology, Oral Microbiology.
    Hänström, L
    Kalfas, S
    Umeå University, Faculty of Medicine, Department of Odontology, Oral Microbiology.
    Caspase 1 involvement in human monocyte lysis induced by Actinobacillus actinomycetemcomitans leukotoxin2003In: Infection and Immunity, ISSN 0019-9567, E-ISSN 1098-5522, Vol. 71, no 8, p. 4448-4455Article in journal (Refereed)
    Abstract [en]

    Actinobacillus actinomycetemcomitans, an oral bacterium implicated in the etiology of periodontal diseases, produces a leukotoxin that selectively lyses primate neutrophils and monocytes, the major populations of defense cells in the periodontium. Though lysis requires expression of the receptor lymphocyte function-associated molecule 1 (LFA-1) on the cell surface, not all LFA-1-expressing leukocyte populations are equally susceptible to the toxin. In this study, the susceptibility of human leukocytes to leukotoxin-induced lysis is compared to their expression of LFA-1 and the activity of caspase 1. Cytolysis was determined by the activity of lactate dehydrogenase released from peripheral human leukocytes after 1-h exposure to leukotoxin. Monocytes were lysed at leukotoxin concentrations of > or = 5 ng/ml, while the corresponding values for neutrophils and lymphocytes were approximately 10 times greater. Similar LFA-1 expression was found in all susceptible cell populations irrespective of their degree of sensitivity to the toxin. Exposure of monocytes to leukotoxin increased their caspase 1 activity about fivefold within 10 to 20 min. Presence of the caspase 1 inhibitor Ac-YVAD-CMK significantly blocked the leukotoxin-induced lysis of monocytes only. At sublytic concentrations, leukotoxin induced no apoptotic activity in monocytes, as revealed by the lack of caspase 3 activation and DNA fragmentation. Monocytes are the most lysis-sensitive leukocytes for A. actinomycetemcomitans leukotoxin. Their lysis by this toxin depends on caspase 1 activation and proceeds through a process that differs from classical apoptosis.

  • 12.
    Kolar, Mallappa Kadappa
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Itte, Vinay N.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Kingham, Paul J.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Novikov, Lev N.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Wiberg, Mikael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Kelk, Peyman
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    The neurotrophic effects of different human dental mesenchymal stem cells2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 12605Article in journal (Refereed)
  • 13.
    Lauvrud, Anne Therese
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Kelk, Peyman
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Wiberg, Mikael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB). Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Hand Surgery.
    Kingham, Paul J.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB).
    Characterization of human adipose tissue-derived stem cells with enhanced angiogenic and adipogenic properties2017In: Journal of Tissue Engineering and Regenerative Medicine, ISSN 1932-6254, E-ISSN 1932-7005, Vol. 11, no 9, p. 2490-2502Article in journal (Refereed)
    Abstract [en]

    Autologous fat grafting is a popular method for soft tissue reconstructions but graft survival remains highly unpredictable. Supplementation of the graft with the stromal vascular fraction (SVF) or cultured adipose tissue-derived stem cells (ASCs) can enhance graft viability. In this study we have examined the phenotypic properties of a selected population of cells isolated from ASCs, with a view to determining their suitability for transplantation into grafts. ASCs were isolated from the SVF of human abdominal fat (n = 8 female patients) and CD146(+) cells were selected using immunomagnetic beads. The angiogenic and adipogenic properties of the positively selected cells were compared with the negative fraction. CD146(+) cells expressed the immunophenotypic characteristics of pericytes. With prolonged in vitro expansion, CD146(-) cells exhibited increased population doubling times and morphological signs of senescence, whereas CD146(+) cells did not. CD146(+) cells expressed higher levels of the angiogenic molecules VEGF-A, angiopoietin-1 and FGF-1. Conditioned medium taken from CD146(+) cells significantly increased formation of in vitro endothelial cell tube networks, whereas CD146(-) cells did not. CD146(+) cells could be differentiated into adipocytes in greater numbers than CD146(-) cells. Consistent with this, differentiated CD146(+) cells expressed higher levels of the adipocyte markers adiponectin and leptin. These results suggest that CD146(+) cells selected from a heterogeneous mix of ASCs have more favourable angiogenic and adipogenic properties, which might provide significant benefits for reconstructive and tissue-engineering applications. Copyright © 2016 John Wiley & Sons, Ltd.

  • 14.
    Pettersson, Linda F.
    et al.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Odontology.
    Kingham, Paul J.
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    Wiberg, Mikael
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy. Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences.
    Kelk, Peyman
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Anatomy.
    In Vitro Osteogenic Differentiation of Human Mesenchymal Stem Cells from Jawbone Compared with Dental Tissue2017In: Tissue Engineering and Regenerative Medicine, ISSN 1738-2696, Vol. 14, no 6, p. 763-774Article in journal (Refereed)
    Abstract [en]

    Autologous bone transplantation is the current gold standard for reconstruction of jawbone defects. Bone regeneration using mesenchymal stem cells (MSC) is an interesting alternative to improve the current techniques, which necessitate a second site of surgery resulting in donor site morbidity. In this study, we compared the osteogenic ability of jawbone MSC (JB-MSC) with MSC from tissues with neural crest origin, namely, the dental pulp, apical papilla and periodontal ligament. All four types of MSC were isolated from the same patient (n = 3 donors) to exclude inter-individual variations. The MSC growth and differentiation properties were characterized. The osteogenic differentiation potential in each group of cells was assessed quantitatively to determine if there were any differences between the cell types. All cells expressed the MSC-associated surface markers CD73, CD90, CD105, and CD146 and were negative for CD11b, CD19, CD34, CD45 and HLA-DR. All cell types proliferated at similar rates, exhibited similar clonogenic activity and could differentiate into adipocytes and osteoblasts. An alkaline phosphatase assay, OsteoImageTM assay for mineralization and qRT-PCR measuring the genes runx2, ALP and OCN, indicated that there were no significant differences in the osteogenic differentiation ability between the various MSCs. In conclusion, we show that from a small segment of jawbone it is possible to isolate sufficient quantities of MSC and that these cells can easily be expanded and differentiated into osteoblasts. JB-MSC appear to be good candidates for future bone regeneration applications in the craniofacial region.

  • 15.
    Pettersson, Mattias
    et al.
    Umeå University, Faculty of Medicine, Department of Odontology.
    Kelk, Peyman
    Umeå University, Faculty of Medicine, Department of Integrative Medical Biology (IMB), Histology and Cell Biology.
    Belibasakis, G. N.
    University of Zurich.
    Bylund, D.
    Mittuniversitetet Sundsvall.
    Molin Thorén, Margareta
    Umeå University, Faculty of Medicine, Department of Odontology.
    Johansson, Anders
    Umeå University, Faculty of Medicine, Department of Odontology.
    Titanium ions form particles that activate and execute interleukin-1β release from lipopolysaccharide-primed macrophages2017In: Journal of Periodontal Research, ISSN 0022-3484, E-ISSN 1600-0765, Vol. 52, no 1, p. 21-32Article in journal (Refereed)
    Abstract [en]

    BACKGROUND AND OBJECTIVE: Peri-implantitis is a destructive inflammatory process characterized by destruction of the implant-supporting bone. Inflammasomes are large intracellular multiprotein complexes that play a central role in innate immunity by activating the release of proinflammatory cytokines. Although inflammasome activation has previously been linked to periodontal inflammation, there is still no information on a potential association with peri-implantitis. The aim of this study was to examine cytotoxic and proinflammatory effects, including inflammasome activation, of metals used in dental implants, in an in vitro model, as well as from clinical tissue samples.

    MATERIAL AND METHODS: Human macrophages were exposed to different metals [titanium (Ti), cobalt, chromium and molybdenum] in a cell-culture assay. Cytotoxicity was determined using the neutral red uptake assay. Cytokine secretion was quantified using an ELISA, and the expression of genes of various inflammasome components was analysed using quantitative PCR. In addition, the concentrations of interleukin-1β (IL-1β) and Ti in mucosal tissue samples taken in the vicinity of dental implants were determined using ELISA and inductively coupled plasma mass spectrometry, respectively.

    RESULTS: Ti ions in physiological solutions stimulated inflammasome activation in human macrophages and consequently IL-1β release. This effect was further enhanced by macrophages that have been exposed to lipopolysaccharides. The proinflammatory activation caused by Ti ions disappeared after filtration (0.22 μm), which indicates an effect of particles. Ti ions alone did not stimulate transcription of the inflammasome components. The Ti levels of tissue samples obtained in the vicinity of Ti implants were sufficiently high (≥ 40 μm) to stimulate secretion of IL-1β from human macrophages in vitro.

    CONCLUSION: Ti ions form particles that act as secondary stimuli for a proinflammatory reaction.

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