| 1. |
- Heiskanen, Annamari, et al.
(författare)
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N-glycolylneuraminic acid xenoantigen contamination of human embryonic and mesenchymal stem cells is substantially reversible.
- 2007
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Ingår i: Stem cells (Dayton, Ohio). - : Oxford University Press (OUP). - 1066-5099 .- 1549-4918. ; 25:1, s. 197-202
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Tidskriftsartikel (refereegranskat)abstract
- Human embryonic and mesenchymal stem cell therapies may offer significant benefit to a large number of patients. Recently, however, human embryonic stem cell lines cultured on mouse feeder cells were reported to be contaminated by the xeno-carbohydrate N-glycolylneuraminic acid (Neu5Gc) and considered potentially unfit for human therapy. To determine the extent of the problem of Neu5Gc contamination for the development of stem cell therapies, we investigated whether it also occurs in cells cultured on human feeder cells and in mesenchymal stem cells, what are the sources of contamination, and whether the contamination is reversible. We found that N-glycolylneuraminic acid was present in embryonic stem cells cultured on human feeder cells, correlating with the presence of Neu5Gc in components of the commercial serum replacement culture medium. Similar contamination occurred in mesenchymal stem cells cultured in the presence of fetal bovine serum. The results suggest that the Neu5Gc is present in both glycoprotein and lipid-linked glycans, as detected by mass spectrometric analysis and monoclonal antibody staining, respectively. Significantly, the contamination was largely reversible in the progeny of both cell types, suggesting that decontaminated cells may be derived from existing stem cell lines. Although major complications have not been reported in the clinical trials with mesenchymal stem cells exposed to fetal bovine serum, the immunogenic contamination may potentially be reflected in the viability and efficacy of the transplanted cells and thus bias the published results. Definition of safe culture conditions for stem cells is essential for future development of cellular therapies.
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| 2. |
- Kauppila, Joonas H, et al.
(författare)
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Intratumoral lactate metabolism in Barrett’s esophagus and adenocarcinoma
- 2017
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Ingår i: Oncotarget. - Stockholm : Karolinska Institutet, Dept of Molecular Medicine and Surgery. - 1949-2553.
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Tidskriftsartikel (refereegranskat)abstract
- Background: Monocarboxylate transporters (MCTs) are cell membrane proteins which transport pyruvate, lactate and ketone bodies across the plasma membrane. MCTs are activated in various cancers, but their expression in esophageal adenocarcinoma is not known. The present study was conducted to elucidate the expression of MCTs in esophageal adenocarcinoma and its precursor lesions. Results: Cytoplasmic MCT1, MCT4 and MTCO1 expression linearly increased from normal epithelium to Barrett's mucosa to dysplasia and cancer. Low cytoplasmic MCT1 expression associated with high T-class (P < 0.01), positive lymph node metastases (P < 0.05), positive distant metastases (P < 0.01) and high tumor stage (P < 0.01). High cytoplasmic MCT4 expression correlated significantly with positive distant metastases (P < 0.05). Both low MCT1 and high MCT4 histoscore predicted survival in univariate analysis (P < 0.01). MCT4 histoscore predicted survival in multivariate analysis (P = 0.043; HR 1.8 95%CI 1.0–3.1). MTCO1 expression was not correlated to clinicopathological variables or survival. Materials and Methods: MCT1, MCT4 and mitochondrial cytochrome c oxidase (MTCO1) expression were determined with immunohistochemistry in esophageal specimens from 129 patients with columnar dysplasia or adenocarcinoma. Specimens including normal esophagus (n = 88), gastric (n = 67) or intestinal metaplasia (n = 51), low-grade (n = 42), high-grade dysplasia (n = 37) and esophageal adenocarcinoma (n = 99) were evaluated. Conclusions: Major increase in markers of tumor metabolism occurs during carcinogenesis and progression of esophageal adenocarcinoma. MCT1 and MCT4 are prognostic factors in esophageal adenocarcinoma.
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| 3. |
- Kauppila, Joonas H, et al.
(författare)
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Tenascin-C and fibronectin in normal esophageal mucosa, Barrett's esophagus, dysplasia and adenocarcinoma
- 2017
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Ingår i: Oncotarget. - Stockholm : Karolinska Institutet, Dept of Molecular Medicine and Surgery. - 1949-2553.
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Tenascin-C and fibronectin are adhesive glycoproteins modulating the structure of the extracellular matrix and cellular functions. Their expression and function in esophageal adenocarcinoma is poorly known. The aim of this study was to evaluate the expression of tenascin-C and fibronectin in esophageal adenocarcinoma and its precursor stages. RESULTS: Stromal tenascin-C and fibronectin expression were found in all evaluated lesion types. Expression of both molecules increased from gastric metaplasia towards adenocarcinoma (p<0.05). In carcinomas, tenascin-C expression in the bulk was associated with T-stage (p=0.006), presence of lymph node (p=0.004) and distant organ metastases (p=0.007). Abundant tenascin-C expression associated with poor survival (p=0.034) in univariate analysis. Fibronectin expression associated to T-stage (p=0.030). Expression of tenascin-C or fibronectin in the tumor invasive front was not associated to clinicopathological variables or survival. No significant correlation with tumor/stroma percentage, cancer-associated fibroblasts or mean vascular density was observed with either tenascin-C or fibronectin. METHODS: Tenascin-C and fibronectin were stained immunohistochemically and assessed in esophageal specimens from patients with esophageal adenocarcinoma (n=90) or dysplasia (n=30). Structures and lesion were evaluated including normal esophagus (n=77), gastric (n=61) or intestinal (n=51) metaplasia without dysplasia, and low-grade (n=42) or high-grade (n=34) dysplasia, and esophageal adenocarcinoma (n=90). In carcinomas, both bulk and invasive front were separately evaluated. In addition, tumor/stroma percentage, cancer-associated fibroblasts and mean vascular density were evaluated. CONCLUSIONS: Tenascin-C and fibronectin are upregulated in esophageal adenocarcinoma when compared to Barrett's esophagus and dysplasia. Increased tenascin-C expression is associated with metastasis and poor prognosis in esophageal adenocarcinoma.
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| 4. |
- Lehenkari, Petri, et al.
(författare)
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The effects of tamoxifen and toremifene on bone cells involve changes in plasma membrane ion conductance
- 2003
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Ingår i: Journal of Bone and Mineral Research. - : Wiley. - 1523-4681 .- 0884-0431. ; 18:3, s. 473-481
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Tidskriftsartikel (refereegranskat)abstract
- Selective estrogen receptor modulators (SERMs), tamoxifen (Tam) and toremifene (Tor), are widely used in the treatment of breast cancer. In addition, they have been demonstrated to prevent estrogen deficiency-induced bone loss in postmenopausal women. These effects are thought to be caused by the interaction of the SERMs with the estrogen receptor, although SERMs have also been shown to conduct non-receptor-mediated effects such as rapid changes in membrane functions. We compared the effects of Tam, Tor, and 17β-estradiol (E2) on the viability of rat osteoclasts and osteoblasts. Both Tam and Tor were found to cause osteoclast apoptosis in in vitro cultures, which was reversed by E2. In addition, at higher concentration (10 μM), both SERMs had an estrogen receptor-independent effect, which involved interaction with the plasma membrane as demonstrated with UMR-108 osteosarcoma cells by Tam and Tor, but not E2. A leak of protons leading to changes in intracellular pH was shown both in medullary bone derived membrane vesicles and in intact cells. These effects were followed by a rapid loss of cell viability and subsequent cell lysis. Our results show that both Tam and Tor have an ionophoric effect on the plasma membranes of bone cells and that these SERMs differed in this ability: Tor induced rapid membrane depolarization only in the presence of high concentration of potassium. These non-receptor-mediated effects may be involved in therapeutic responses and explain some clinical side effects associated with the treatment of patients with these SERMs
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| 5. |
- Leskela, Hannu-Ville, et al.
(författare)
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Calcification and cellularity in human aortic heart valve tissue determine the differentiation of bone-marrow-derived cells
- 2006
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Ingår i: Journal of Molecular and Cellular Cardiology. - : Elsevier BV. - 1095-8584 .- 0022-2828. ; 41:4, s. 642-649
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Tidskriftsartikel (refereegranskat)abstract
- Human bone-marrow-derived mesenchymal stem cells (MSC) are responsible the remodeling of human tissue. However, damaged aortic valves are lack the ability to regenerate which is an active cell-mediated process. Diseased aortic valve remodeling has similarities even to bone formation. In this study, the prerequisites for cultured MSCs to undergo osteoblastic differentiation on aortic valves were explored. An ex vivo model using a human aortic valve microenvironment was developed. The expression of type I procollagen, alkaline phosphatase activity, osteocalcin secretion and osteocalcin immunostaining were studied to evaluate the induction of osteogenesis of the MSCs on noncalcified and calcified human aortic valves. Aortic valves were exposed to freeze-thaw injury to devitalize valves in order to separately study the role of valve matrix vs. endothelial cells in the explants. Thus, valves were assigned to 1 of 4 treatment groups: noncalcified uninjured valves, calcified uninjured valves, noncalcified injured and calcified injured. Finally, valves were decalcified to separately explore the effect of a calcified matrix on the osteogenesis. In this co-culture system, the noncalcified uninjured valves inhibited osteogenesis of MSCs, whereas the calcified valves promoted differentiation towards osteoblastic lineage. Devitalization of the valve matrix inflicted a significant increase in the osteogenesis of co-cultured MSCs. Calcified matrix in the valves seemed to have a role in the spontaneous osteogenesis of the MSCs. This spontaneous matrix induced differentiation of MSCs into osteoblast lineage could not be inhibited by pravastatin, indomethacin or tetracycline. In conclusion, these results suggest that interactions between MSCs and aortic valve matrix components and cells modulate MSC phenotype in this environment. Further studies are required to characterize this interesting phenomenon in greater detail.
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| 6. |
- Leskela, Hannu-Ville, et al.
(författare)
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Osteoblast recruitment from stem cells does not decrease by age at late adulthood
- 2003
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Ingår i: Biochemical and Biophysical Research Communications. - : Elsevier BV. - 1090-2104 .- 0006-291X. ; 311:4, s. 1008-1013
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Tidskriftsartikel (refereegranskat)abstract
- This study was aimed to characterize the ability of human bone marrow mesenchymal stem cells (MSC) to differentiate into osteoblasts in vitro. Twenty-three women and 20 men at late adulthood (52-92 years of age) were selected for the study. MSCs were isolated and cultured in vitro and alkaline phosphatase (ALP) activity, secretion of amino-terminal propeptide of type I procollagen (PINP), type III procollagen (PIIINP) and osteocalcin were analyzed. Matrix mineralization was analyzed by the von Kossa staining and by calcium quantification. We found that the ALP and PINP levels compared with control increased to 2.8- and 2.9-fold, respectively, when cells were cultured for three weeks. ALP activity, PINP and calcium deposition in response to dexamethasone treatment increased by age in women and was unchanged in men. Overall our data suggests that the osteogenic potential of MSCs does not decrease by age in either women or men at late adulthood.
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| 7. |
- Persson, Maria, et al.
(författare)
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Effect of bioactive extruded PLA/HA composite films on focal adhesion formation of preosteoblastic cells
- 2014
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Ingår i: Colloids and Surfaces B. - : Elsevier BV. - 0927-7765 .- 1873-4367. ; 121, s. 409-416
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Tidskriftsartikel (refereegranskat)abstract
- The quality of the initial cell attachment to a biomaterial will influence any further cell function, including spreading, proliferation, differentiation and viability. Cell attachment is influenced by the material's ability to adsorb proteins, which is related to the surface chemistry and topography of the material. In this study, we incorporated hydroxyapatite (HA) particles into a poly(lactic acid) (PLA) composite and evaluated the surface structure and the effects of HA density on the initial cell attachment in vitro of murine calvarial preosteoblasts (MC3T3-EI). Scanning electron microscopy (SEM), atomic force microscopy (AFM) and infrared spectroscopy (FTIR) showed that the HA particles were successfully incorporated into the PLA matrix and located at the surface which is of importance in order to maintain the bioactive effect of the HA particles. SEM and AFM investigation revealed that the HA density (particles/area) as well as surface roughness increased with HA loading concentration (i.e. 5, 10, 15 and 20wt%), which promoted protein adsorption. Furthermore, the presence of HA on the surface enhanced cell spreading, increased the formation of actin stress fibers and significantly improved the expression of vinculin in MC3T3-E1 cells which is a key player in the regulation of cell adhesion. These results suggest the potential utility of PLA/HA composites as biomaterials for use as a bone substitute material and in tissue engineering applications.
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| 8. |
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