In vitro expansion of autonomously contracting, cardiomyogenic structures from rainbow trout Oncorhynchus mykiss.

In primary cell preparations from larvae of rainbow trout Oncorhynchus mykiss, the formation of autonomously contracting cell aggregates was observed after 7 days. These contracting elements could be propagated and some aggregates were maintained over a period of 35 days. Electron microscopical and immunocytochemical examination revealed the presence of cardiomyocytes.

The influence of pancreas-derived stem cells on scaffold based skin regeneration.

It has been shown that Pancreatic Stem Cells (PSCs) share many features with skin stem cells. Yet, their potential role in skin regeneration remains to be elucidated. 5x10(5) PSCs from male Rattus norwegicus were seeded on Matriderm scaffold overnight. Cells survival and proliferation were then tested in vitro showing the survival of the cells and their homogenous distribution in the scaffolds. Afterwards, scaffolds were used to replace bilateral full-thickness skin wounds made on the dorsum of Nu/Nu mice. A control group of nude mice received the Matriderm scaffolds without cells. Two weeks after transplantation, wound areas were harvested and analyzed with respect to epithelialization, vascularization and wound closure. The healing area and regeneration rate were significantly increased in the group used the PSCs-seeded scaffolds (factor of 2.1). Vascularization rate showed a significant increase in the PSCs-seeded scaffolds(factor of 1.5). Morphology and immunohistochemistry showed new skin-like structures positive to epidermal markers in the healing wound bed. PSCs were detected in the regenerated tissues. This study showed that the combined use of PSCs with the Matriderm as a scaffold for dermal regeneration significantly increased the epidermalization, vascularization and healing in full-thickness wounds.

In vitro cultures of human pancreatic stem cells: gene and protein expression of designated markers varies with passage.

Adult stem cells may possess great plasticity, but the cellular mechanisms regulating their fate are not fully understood. Prior to application of stem cell populations in regenerative medicine, major challenges remain to be overcome. Fundamental questions about in vitro growth and spontaneous differentiation of adult stem cell populations must be resolved. In this study, we comprehensively characterized a stem cell population derived from human pancreatic tissue by analyzing mRNA and protein expression in consecutive passages. We examined transcription and protein expression levels of markers related to stem cells or differentiated cells, respectively, as well as the growth rate of a primary human pancreatic stem cell population. In particular, the course of spontaneous mRNA and protein expression of the genes for alpha-smooth muscle actin (alpha-SMA), neurofilaments (NF), cytokeratin 18 (CK18) and nestin was examined during 11 passages by means of RT-PCR and immunocytochemistry. The cell population showed exponential growth over 10 of the 11 examined passages. Both the spontaneous expression of stem cell-related mRNA and protein as well as the characteristics of spontaneous differentiation were variable. Changes in mRNA and protein expression showed no direct correlation. These results demonstrate the unpredictable behaviour of spontaneously differentiating stem cells, being influenced by numerous, barely traceable extrinsic factors. Characterization studies of stem cell populations therefore require improved analysis techniques together with strictly controlled cell cultivation conditions to improve global gene and protein expression analyses.

Long-term culture of a cell population from Siberian sturgeon (Acipenser baerii) head kidney.

In vitro cultures of native fish cell lines are of great importance, both for basic research and applied science. In particular, there is strong demand for long-term growable cell lines from breeding fish, like sturgeon. Here, we describe the culture of cells from Siberian sturgeon (Acipenser baerii) head kidney. The cells have so far been cultured over a period of 12 months (24 passages). Cytochemical and immunocytochemical examination suggests that, in vitro, the cells exhibit markers that are indicative for different cell types. In particular, fat storing cells (adipocytes) were observed, and the expression of cytokeratins and glial fibrilar acidic protein (GFAP) can be concluded on the basis of immuncytochemical analysis. The observation of different morphologies additionally underlines the heterogeneity of the cell population and matches the typical behaviour of in vitro cultures of stem/progenitor cells. Different applications can be imagined.