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Trehalose is a nontoxic disaccharide and a promising cryoprotection agent for medically applicable cells. In this study, the efficiency of combining trehalose with reversible electroporation for cryopreservation of two types of human mesenchymal stromal cells was investigated: adipose-derived stromal cells, and umbilical-cord-derived stromal cells. Comparable results to standard dimethyl sulfoxide cryopreservation protocols were achieved, even without extensive electroporation parameters and protocol optimization. The presence of high extracellular trehalose resulted in comparable cell viabilities without and with electroporation. According to the determination of trehalose concentrations, 250 mM extracellular trehalose resulting in, 20 mM to 50 mM intracellular trehalose were sufficient for successful cryopreservation of cells. With electroporation, higher (i.e. 50 mM to 90 mM) intracellular trehalose was achieved after cryopreservation, although cell survival was not improved significantly. To evaluate the impact of electroporation and cryopreservation on cells, stress and immune-activation-related gene expression were analyzed. Electroporation and/or cryopreservation resulted in increased SOD2 and HSPA1A expression. Despite the increased stress response, the high up-regulation by mesenchymal stromal cells of immunomodulatory genes in the inflammatory environment was not affected. Highest expression was seen for the IDO1 and TSG6 genes. In conclusion, cryopreservation of mesenchymal stromal cells in trehalose results in comparable characteristics to their cryopreservation using dimethyl sulfoxide. [ABSTRACT FROM AUTHOR]

New cryopreservation approaches for medically applicable cells are of great importance in clinical medicine. Current protocols employ the use of dimethyl sulfoxide (DMSO), which is toxic to cells and causes undesirable side effects in patients, such as cardiac arrhythmias, neurological events, and others. Trehalose, a nontoxic disaccharide, has been already studied as a cryoprotectant. However, an efficient approach for loading this impermeable sugar into mammalian cells is missing. In our study, we assessed the efficiency of combining reversible electroporation and trehalose for cryopreservation of human adipose-derived stem cells. First, we determined reversible electroporation threshold by loading of propidium iodide into cells. The highest permeabilization while maintaining high cell viability was reached at 1.5 kV/cm, at 8 pulses, 100 µs, and 1 Hz. Second, cells were incubated in 250 or 400 mM trehalose and electroporated before cryopreservation. After thawing, 83.8 ± 1.8 % (mean ± SE) cell recovery was obtained at 250 mM trehalose. By using a standard freezing protocol (10 % DMSO in 90 % fetal bovine serum), cell survival after thawing was about 91.5 ± 1.6 %. We also evaluated possible effects of electroporation on cells' functionality before and after thawing. Successful cell growth and efficient adipogenic and osteogenic differentiation were achieved. In conclusion, electroporation seems to be an efficient method for loading nonpermeable trehalose into human adipose-derived stem cells, allowing long-term cryopreservation in DMSO-free and xeno-free conditions. [ABSTRACT FROM AUTHOR]

Autologous transplantation of chondrocytes is currently being promoted as a novel approach for the treatment of deep cartilage lesions. Briefly, the method involves enzyme-mediated release of chondrocytes from cartilage biopsies, the expansion of cells by in vitro cultivation and their re-implantation into the defect. The success of this technique depends on many factors including transport conditions for both, cartilage biopsies from the operating hall to the laboratory and the return transport of final suspension of cultured chondrocytes. To determine the extent of cellular damage in biopsies, chondrocytes were enzymatically isolated following a few days of tissue preservation in different tissue culture media. The proportion of dead cells was assessed by Trypan blue staining and counting. The viability was not dependant of the type of the medium used and remained approximately 50% in all samples, even after 72 h. To develop optimal conditions for transport of final chondrocyte suspension, isolated cells were firstly grown in monolayer cultures. Cell suspensions in media with different additives were injected into special glass containers used for the transport and left at 4°C or 25°C for up to 3 days. During this period every 24 h the samples were taken and viability as well as apoptosis levels were assessed. Viability of cells in suspensions at 25°C decreased significantly and became inadequate already after 48 h. In contrast to that, the proportion of viable cells at 4°C remained above 80% even after 48 h. In the majority of the samples, culture medium containing serum and vitamin C provided the best conditions for long-term preservation of chondrocytes. [ABSTRACT FROM AUTHOR]

Chondrocytes present in articular cartilage survive as a resident cell population throughout the lifespan of the individual organism. However, articular chondrocytes as other cells also undergo apoptosis and there is an ever increasing list of diverse stimuli that can induce this phenomenon in vitro. Our main interest was to investigate potential cytotoxic effects of vitamin C (L-ascorbic acid) on human articular chondrocytes. The present study suggests that vitamin C can induce apoptosis in a cell culture of chondrocytes after 18 h of cultivation. Apoptosis-inducing activity of L-ascorbic acid is dose dependent and significantly affected by the presence of serum. The increased number of vitamin C induced apoptotic cells was associated with DNA fragmentation and morphological changes of the cells. [ABSTRACT FROM AUTHOR]

Chondrocytes in hyaline cartilage produce typical matrix proteins, the most abundant of them being collagen type II and aggrecan. Chondrocytes in monolayer cell culture dedifferentiate and gain fibroblastic phenotype. The cells gradually start to produce collagen type I while the production of collagen type II and aggrecan decreases. Transplantation of autologous chondrocytes cultured in vitro is used for treatment of aseptic articular cartilage lesions. For this purpose, cartilage biopsy is taken and isolated cells are subsequently proliferated in a monolayer cell culture. When implanted, the cells start to produce specific cartilaginous matrix that fills the defect. Prior to surgical procedure the cells can also be cryopreserved for longer periods of time after reaching appropriate numbers. We tested the influence of cultivation time and number of continuous culture passages as well as the influence of cryopreservation on the matrix protein synthesis of human articular chondrocytes. The ability of dedifferentiated chondrocytes to redifferentiate has been monitored by measuring matrix protein synthesis of the cells, re-seeded in agarose suspension culture. The results obtained show progressive dedifferentiation during monolayer cell culture procedures, facilitated by cryopreservation. Successful redifferentiation of cells re-seeded in suspension cultures was observed regardless of the previous level of chondrocyte dediferentiation. [ABSTRACT FROM AUTHOR]

Investigation of allo- and autoreactivity of cartilage components is useful not only for the potential allogeneneic transplantation but also for the treatment of tissue specific degenerative autoimmune diseases. We generated dendritic cells (DCs) to study articular cartilage immunogenicity, by using human peripheral blood mononuclear cells. Dendritic cells are extremely efficient antigen-presenting cells that initiate and modulate T-cell dependant immune responses. After isolation by density centrifugation, GM-CSF and IL-4 were added to adherent mononuclear cells. After 7 days of cultivation the cells in cell culture were: HLA-DR++, CD86+, CD14-, CD80-, CD83, CD19-, CD56-, CD3-. Dendritic cells were then pulsed with a supernatant taken from primary monolayer cell cultures of human allogeneic chondrocytes. The stimulating capacity of antigen-pulsed DCs was measured in a classical proliferation assay using tritium labelled thymidine as a marker of mitosis. Proliferative responses were significantly strong but became much stronger when DCs were concomitantly incubated with soluble antigens and human recombinant TNF-α and used subsequently as stimulators. Although TNF-α positively influenced the stimulating capacity of pulsed DCs, we were unable to detect major differences in expression of specific DCs’ phenotype markers assessed by flow cytometry in the absence or presence of this cytokine. [ABSTRACT FROM AUTHOR]

Basic functional test for evaluation of in vitro cultured human dendritic cells (DC) is primary allogeneic one-way mixed lymphocyte reaction (MLR). In this way, one can evaluate stimulating capacity, which is a basic characteristic of DC. The proliferation of cells is measured through incorporation of 3H-thymidine. Normally proliferation is measured at days 5-7. We studied kinetics of proliferative responses initiated with different stimulating cell suspensions to evaluate differences and possibly reduce time needed to perform this test. Gradual increase in response from days 1 to 7 and a significant difference from controls (peripheral blood mononuclear cells) seen from day 4 was noted if macrophages were used as stimulators. A consistently higher proliferation, compared to controls, was always found already on day 2 when mature DC were used as stimulators. The reaction peaked 2 to 3 days earlier and was also more than two times more intense. This maximal and significantly higher response, consistently seen already after 48 hours, allows us to confirm the presence of mature DC in stimulating suspensions much earlier than previously. [ABSTRACT FROM AUTHOR]