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Myocardial infarction is underoxygenation-driven limited necrosis of heart tissues which results in elimination of ca. 0.5 to 1 billion spontaneously contracting cardiomyocytes (CM). Since the ability of human heart to regenerate is limited, efforts have been undertaken to increase the number of cardiomyocytes in post-infarction myocardium. Theoretically, such proposals might involve transplantation of 1) skeletal myoblasts and cardiomyocytes, or 2) progenitor/stem cells, theoretically capable of differentiating into cardiomyocytes, or 3) pluripotent cells such as embryonal stem cells (ESC) and induced pluripotent stem cells (iPSC) differentiating into cardiomyocytes. The efforts to increase CM could also involve 4) in situ reprogramming of fibroblasts into active cardiomyocyte-like cells, or 5) stimulating in situ proliferation of cardiomyocytes using pharmacological agents. Only three proposals merit closer scrutiny (2, 4 and 5). However, preclinical and clinical data have demonstrated weak ability of progenitor cells to differentiate (proposal 2). Nevertheless, transplanted cell-induced paracrine effects accompanying such therapy do improve functioning of the damaged heart muscle. The proposals that would permit the number of CM to be increased include in situ reprogramming of fibroblasts into active cardiomyocytes (proposal 4), as well as in situ stimulation of quiescent cardiomyocytes' proliferation (proposal 5). It appears that an optimized therapeutic solution (increasing left ventricular ejection fraction and decreasing the post-infarct scar) might combine agents stimulating paracrine effects and reprogramming of fibroblasts.

Wound healing is an important biological process of crucial value for organisms survival and retention of its proper functions. The recognition of molecular mechanisms of these phenomenon is still under investigation. The transition of mesenchymal fibroblasts to myofibroblasts is a key point in wound healing. The contraction ability of myofibroblast enables the shrinkage of a wound and closes its edges. Alpha smooth muscle actin (alpha-SMA), one of six actin isoforms, is a marker of compeletely differentiated myofibroblast. The regulation of differentiation process depends on many growth factors (especially TGF beta 1), the level of active thymosin beta 4, extracellular matrix proteins--including fibronectin, and also on specificity of microenvironment. Thymosin beta 4 is responsible for maintenance of pool of monomeric actin and actin filaments depolymerization. It can also act as a transcription factor, migration stimulator and immunomodulator, so this protein deserves for more attention in wound healing research field.

The lens epithelial cells of A and E type are involved in pathogenesis of posterior capsule opacification (PCO). They undergo metaplasia into microfibroblasts, then migrate towards posterior capsule where they proliferate and form opacification. These processes are stimulated by cytokines and interleukines. The extracellular matrix which constitutes a scaffold for migration and attachment of epithelial cells plays an important role in PCO formation. Integrines intercede in this process.

Unlabelled: To develop a tissue-engineered bladder wall replacement with elements obtained from non-urinary tract components is an atractive idea. The aim of this study was to compare growth of hair follicles epithelial stem cells and mesenchymal stem cells to urothelial cells and fibroblasts cells on scaffold prepared from rat collagen type I., Materials and Methods: Wistar rats were used in experiment. Rat urothelial cells, hair follicles epithelial stem cells, mesenchymal stem cells and 3T3 cells were cultivated in DMEM (Sigma) supplemented with 10% (or 20% for hair follicles cells) of Fetal Bovine Serum (FBS). Epithelial cell cultures were suplemented with EGF (10 ng/ml; Sigma). Cells were stained using anti-cytokeratine (Clone MMF) and anti-cytokeratine 7. Anti-CD34 and anti-p63 staining were done. Collagen scaffold was prepared from tendoms of Wistar rat's tails. 6-well plates were covered with collagen scaffold. 25 x 10(3) of cells were seeded on each well and cultured for a week. Cells in the controls were seeded on polystyrene surface. After a week cell viability was assessed using MTT test (Sigma). Each experiment was triplicated. Photo documentation was prepared. The differences between means were compared using t-Student test., Results: There were 106.5 +/- 23.4 x 10(3) and 310.7 +/- 60.7 x 10(3) of 3T3 fibroblasts growing on polystyrene and collagen, respectively (p < 0.05). The initial cell number was 25.0 x 10(3). Urothelial cells expressed epithelial markers. There were 40.0 +/- 4.2 x 10(3) and 4.5 +/- 1.8 x 10(3) urothelial cells growing on polystyrene and collagen, respectively after 7 days of culture (p < 0.01). There were 118.5 +/- 19.7 x 10(3) and 114.1 +/- 33.2 x 0(3) of mesenchymal stem cells growing on polystyrene and collagen, respectively (NS). Hair follicles epithelial cells expressed epithelial markers and were slightly positive for CD34 and p63. There were 292.5 +/- 33.3 x 10(3) and 167.4 +/- 24.9 x 10(3) of hair follicles epithelial cells growing on polystyrene and collagen, respectively (p < 0.05). Collagen scaffold decreased proliferation of follicle epithelial and urothelial cells., Conclusions: Hair follicles epithelial stem cells and mesenchymal stem cells can be potentially used in tissue-engineering, with the guarantee of the sufficient cell number for transplantation. It seems that construction in vitro of urinary bladder walls from elements obtained from non-urinary tract tissues is feasible.

The performed evaluation covers the elastic fibre elements in the dermis of rabbits after the preparation of 30% elastin in propylene glycol was rubber in. Moreover, the effect of elastin on the degree of proliferation of fibroblasts, isolated from the rabbit's skin, was determined in vitro. It has been found out that the used preparation exerts a stimulating effect on elastogenesis, but no differences in the degree of proliferation of the fibroblasts under in vitro condition were observed.

The paper presents recent data concerning the effect of growth factors on the metabolism of collagen, collagenases and glycosaminoglycans in vitro. The hypotheses of the mitogenic action of peptide factors and their role in the control of synthesis and breakdown of polyphosphoinositides are also reviewed.