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Budapest, Hungary

Szepesi A.,Hungarian Academy of Sciences | Szepesi A.,Creative Cell Ltd | Matula Z.,Hungarian Academy of Sciences | Szigeti A.,Hungarian Academy of Sciences | And 5 more authors.
Stem Cells and Development

Periodontal ligament stem cells (PDLSCs) provide an important source for tissue regeneration and may become especially useful in the formation of osteogenic seeds. PDLSCs can be cultured, expanded, and differentiated in vitro; thus, they may be applied in the long-term treatment of the defects in the dental regions. Here we studied numerous potential markers allowing the selection of human PDLSCs with a maximum differentiation potential. We followed the expression of the ATP-binding cassette subfamily G member 2 (ABCG2) membrane transporter protein and isolated ABCG2-expressing cells by using a monoclonal antibody, recognizing the transporter at the cell surface in intact cells. The expression of the ABCG2 protein, corresponding to the so-called side-population phenotype in various tissue-derived stem cells, was found to be a useful marker for the selection of PDLSCs with enhanced osteogenic, chondrogenic, and adipogenic differentiation. These findings may have important applications in achieving efficient dental tissue regeneration by using stem cells from extracted teeth. © 2015 Mary Ann Liebert, Inc. Source

Tatrai P.,Hungarian Academy of Sciences | Tatrai P.,Debrecen University | Szepesi A.,Creative Cell Ltd | Matula Z.,Creative Cell Ltd | And 7 more authors.
Biochemical and Biophysical Research Communications

Adipose tissue-derived stromal cells (ASCs) are increasingly being studied for their usefulness in regenerative medicine. However, limited life span and donor-dependent variation of primary cells such as ASCs present major hurdles to controlled and reproducible experiments. We therefore aimed to establish immortalized ASC cell lines that provide steady supply of homogeneous cells for in vitro work while retain essential features of primary cells. To this end, combinations of human telomerase reverse transcriptase (hTERT), murine Bmi-1, and SV40 large T antigen (SV40T) were introduced by lentiviral transduction into ASCs. The resulting cell lines ASC hTERT, ASC Bmi-1, ASC Bmi-1+hTERT and ASC SV40T+hTERT were tested for transgene expression, telomerase activity, surface immunomarkers, proliferation, osteogenic and adipogenic differentiation, karyotype, tumorigenicity, and cellular senescence. All cell lines have maintained expression of characteristic surface immunomarkers, and none was tumorigenic. However, ASC Bmi-1 had limited replicative potential, while the rapidly proliferating ASC SV40T+hTERT acquired chromosomal aberrations, departed from MSC phenotype, and lost differentiation capacity. ASC hTERT and ASC hTERT+Bmi-1, on the other hand, preserved all essential MSC features and did not senesce after 100 population doublings. Notably, a subpopulation of ASC hTERT also acquired aberrant karyotype and showed signs of transformation after long-term culture. In conclusion, hTERT alone was sufficient to extend the life span of human ASC, but ASC hTERT are prone to transformation during extensive subculturing. The combination of Bmi-1 and hTERT successfully immortalized human ASCs without significantly perturbing their phenotype or biological behavior. © 2012 Elsevier Inc. Source

Tatrai P.,Hungarian Academy of Sciences | Sagi B.,Stem Cell Laboratory | Szigeti A.,Creative Cell Ltd | Szepesi A.,Creative Cell Ltd | And 10 more authors.
Journal of Materials Science: Materials in Medicine

Seeding of bone implants with mesenchymal stem cells (MSCs) may promote osseointegration and bone regeneration. However, implant material surfaces, such as titanium or bovine bone mineral, fail to support rapid and efficient attachment of MSCs, especially under serum-free conditions that may be desirable when human applications or tightly controlled experiments are envisioned. Here we demonstrate that a branched poly[Lys(Seri-DL-Alam)] polymer functionalized with cyclic arginyl-glycyl-aspartate, when immobilized by simple adsorption to tissue culture plastic, surgical titanium alloy (Ti6Al4V), or Bio-Oss® bovine bone substitute, significantly accelerates serum-free adhesion and enhances seeding efficiency of human adipose tissue-derived MSCs. Moreover, when exposed to serum-containing osteogenic medium, MSCs survived and differentiated on the peptide-coated scaffolds. In summary, the presented novel polypeptide conjugate can be conveniently used for coating various surfaces, and may find applications whenever quick and efficient seeding of MSCs is required to various scaffolds in the absence of serum. © 2012 Springer Science+Business Media New York. Source

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