The enormous need for 'spare parts' for the human body is the driving force for research in a new scientific field - tissue engineering. Tissue engineering combines living cells with a wide range of biomaterials, mostly as a substitute for the extracellular matrix or the stroma. As experiments in conventional culture dishes continued to fail, new cell and tissue culture methods had to be developed. Tissues are cultured under conditions as close as possible to their natural environment. Cells are grown on novel tissue carriers, on selected biomaterials and scaffolds. The tissues are subsequently transferred into different types of containers for perfusion with fresh culture medium. The development of artificial skin for severely burned patients is among the most advanced tissue-engineering attempts. Intensive research is being focused on the generation of artificial cartilage and bones to treat articular joint diseases or injuries or augment defects in plastic surgery. Future challenges are the construction of liver organoids for bridging comas or bioartificial pancreas for the treatment of type I diabetes mellitus. In this paper we show strategies, needs, tools for the development of some artificial tissues and bioartificial organs.
Pollen proteases were discovered over 100 years ago, whereas the enzymes from female tissues have been used since the Roman era in simple biotechnological processes. In the last decade a great progress has been made in studies on plant proteases, including those from the generative organs. This paper reviews reports published in the last decade, concerning purification, properties and localization of proteases from generative parts of flowering plants against the background of the general proteolytic machinery of the plant. Special attention is paid to differences in protease structure and properties in comparison to other enzymes from the same catalytic classes. Participation of the proteases in all steps of pollen-pistil interaction as well as in pollen tube growth is discussed. Further intensive studies with use of native substrates are necessary to understand the role of proteases in pollination.
2 The human fibrinolytic system comprises an inactive proenzyme ? plasminogen which can be converted to the active form ? plasmin which, in turn, degrades fibrin clots into soluble fibrin degradation products. Tissue plasminogen activator (t-PA) has been identified as a main physiological factor responsible for plasminogen - plasmin conversion. The high fibrin specificity of t-PA, which allows efficient activation on the surface of fibrin clots, has stimulated great interest in its preparation to be used for thrombolytic therapy. Several approaches have been followed to further improve the thrombolytic properties of recombinant t-PA by protein engineering to enhance its plasminogen - activating potency as well as fibrin specificity, and to reduce its plasma clearance. One of the approaches involves the conjugation of its deletion variant, so called K2L-tPA, to various biomolecules. K2L-tPA is a 351-aminoacid C-terminal fragment of human t-PA. The protein is composed of two major domains: Kringle-2 (K2), responsible for fibrin binding, and so-called Light Chain domain (L), containing active centre of the enzyme. In this paper, we describe our efforts on expression of synthetic gene coding for K2L-tPA, and on renaturation and purification of recombinant protein
The complete coding sequences of porcine genes NCF2, BCKDHB and BCKDHA were amplified by using reverse transcriptase polymerase chain reaction (RT-PCR), basing on the conserved coding sequence information of humans or other mammals. These 3 novel porcine genes were then assigned GeneIDs: 100142665, 100142669 and 100142666. The phylogenetic tree analysis revealed that the porcine NCF2, BCKDHB and BCKDHA all are most closely related to the bovine NCF2, BCKDHB and BCKDHA. Tissue expression profile analysis revealed that porcine NCF2, BCKDHB and BCKDHA genes were differentially expressed in tissues, including skeletal muscle, the heart, liver, fat, kidney, lung, small and large intestine.
It is well documented that most if not all aspects of mast cell development, including growth, proliferation, and the differentiation/maturation are regulated by cytokines. Nowadays there is growing evidence that cytokines also influence the biology and function of mature tissue mast cells. Some cytokines activate mast cells directly to mediator release or modulate their reactivity to other stimulating agents. Various cytokines affect mast cells migration and expression of cell receptors, at the same time regulating the survival of tissue mast cells. Taking into account that mast cells themselves are the source of many cytokines (both preformed and newly generated) it can be assumed that these cytokines regulate the function of mast cells in tissues in autocrine manner
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