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The main goal of this study was a comparison of biological properties of mesenchymal stromal cells (MSCs) obtained from bone marrow, adipose tissue and umbilical cord with respect to articular cartilage regeneration. MSCs were isolated and expanded in vitro up to the third passage. The kinetics of proliferation was analyzed by cell analyzer CEDEX XS and expression of selected markers was assessed by flow cytometry. The morphology was analyzed by inverted microscope and TEM. Pellet culture system and chondrogenic medium containing TGF-β1 was used to induce chondrogenic differentiation. Chondrogenesis was analyzed by real-time PCR; the expression of collagen type I and type II was compared. MSCs from all sources showed similar kinetics of proliferation and shared expression of CD73, CD90 and CD105; and were negative for CD14, CD20, CD34 and CD45. Observation under inverted microscope and TEM showed similar morphology of all analyzed MSCs. Cells from all sources underwent chondrogenic differentiation - they expressed collagen type II and acid mucopolysaccharides typical for hyaline cartilage. On the basis of obtained results it should be emphasized that MSCs from bone marrow, adipose tissue and umbilical cord share biological properties. They possess the chondrogenic potential and may be utilized in cartilage tissue engineering.

White adipose tissue was long perceived as a passive lipid storage depot but it is now considered as an active and important endocrine organ. It also harbours not only adipocytes and vascular cells but also a wide array of immunologically active cells, including macrophages and lymphocytes, which may induce obesity-related inflammation. Recently, adipose tissue has been reported as a source of adult mesenchymal stem cells with wide use in regenerative medicine and tissue engineering. Their relatively non-complicated procurement and collection (often performed as liposuction during aesthetic surgery) and grand plasticity support this idea even more. We focused our research on exploring the issues of isolation and long-term cultivation of mesenchymal stem cells obtained from adipose tissue. Ultra-structural morphology of the cells cultivated in vitro has been studied and analysed in several cultivation time periods and following serial passages--up to 30 passages. In the first passages they had ultra-structural characteristics of cells with high proteosynthetic activity. Within the cytoplasm, big number of small lipid droplets and between them, sparsely placed, small and inconspicuous, electron-dense, lamellar bodies, which resembled myelin figures were observed. The cells from the later passages contained high number of lamellar electron-dense structures, which filled out almost the entire cytoplasm. In between, mitochondria were often found. These bodies were sometimes small and resembled myelin figures, but several of them reached huge dimensions (more than 1 µm) and their lamellar structure was not distinguishable. We did not have an answer to the question about their function, but they probably represented the evidence of active metabolism of lipids present in the cytoplasm of these cells or represented residual bodies, which arise after the breakdown of cellular organelles, notably mitochondria during long-term cultivation.

Somatic stem cells possess unique properties of self-renewal and plasticity which make them promising candidates for use in tissue engineering and regenerative medicine, in addition to serving as efficient delivery vehicles in site-specific therapy. In the case of therapeutic application, it is essential to isolate and culture stem cells in vitro, to obtain them in sufficient quantities. Although long-term cultivation provides an adequate number of cells, it has been shown that this approach is associated with increased risk of transformation of cultured cells, which presents a significant biological hazard. This article reviews information about biological features and cellular events which occur during long-term cultivation of somatic stem cells, with respect to their safe utilization in potential clinical practice.

Somatic stem cells posses an exclusive property of self regeneration and plasticity which makes them promising candidates for use in tissue engineering and regenerative medicine. In the case of stem cell therapy it is crucial to obtain them in sufficient amount. That's why they have to be cultured under in vitro conditions. Long term culture provides adequate number of cells, but on the other hand it is associated with increased risk of spontaneous cell transformation. In this study we analyzed the effect of serial passaging (up to 10th passage) on the morphological and selected biological characteristics of human stem cells isolated from adipose tissue in respect to potential malignant transformation. Obtained results showed that human adipose tissue-derived stem cells maintained their morphological and biological properties during 10 passages and after performing further tests mainly addressed the cytogenetic stability and expression of regulators of cell cycle, senescence and apoptosis, they should be safely used in clinical practice.