RESUMO
We compared the structure and mechanical properties of scaffolds based on pure collagen, pure chitosan, and a mixture of these polymers. The role of the composition and structure of scaffolds in the maintenance of cell functions (proliferation, differentiation, and migration) was demonstrated in two experimental models: homogeneous tissue analogues (scaffold populated by fibroblasts) and complex skin equivalents (fibroblasts and keratinocytes). In contrast to collagen scaffolds, pure chitosan inhibited the growth of fibroblasts that did not form contacts with chitosan fibers, but formed specific cellular conglomerates, spheroids, and lose their ability to synthesize natural extracellular matrix. However, the use of chitosan as an additive stimulated proliferative activity of fibroblasts on collagen, which can be associated with improvement of mechanical properties of the collagen scaffolds. The effectiveness of chitosan as an additional cross-linking agent also manifested in its ability to improve significantly the resistance of collagen scaffolds to fibroblast contraction in comparison with glutaraldehyde treatment. Polymer scaffolds (without cells) accelerated complete healing of skin wounds in vivo irrespective of their composition healing, pure chitosan sponge being most effective. We concluded that the use of chitosan as the scaffold for skin equivalents populated with skin cells is impractical, whereas it can be an effective modifier of polymer scaffolds.
Assuntos
Quitosana/química , Alicerces Teciduais/química , Animais , Proliferação de Células , Forma Celular , Células Cultivadas , Meios de Cultura/química , Módulo de Elasticidade , Fibroblastos/fisiologia , Humanos , Queratinócitos/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Engenharia Tecidual , CicatrizaçãoRESUMO
The problem considered is how one transcription factor controls numerous processes in the organism. The mechanisms determining the multiplicity of Oct-1 functions are described.
Assuntos
Proteínas de Ligação a DNA/fisiologia , Fatores de Transcrição/fisiologia , Processamento Alternativo , Sequência de Aminoácidos , Animais , Sequência de Bases , Diferenciação Celular , Proteínas de Ligação a DNA/química , Expressão Gênica , Fator C1 de Célula Hospedeira , Humanos , Dados de Sequência Molecular , Morfogênese , Fator 1 de Transcrição de Octâmero , Homologia de Sequência de Aminoácidos , Fatores de Transcrição/químicaRESUMO
Expression of the oct-2 gene was studied in mouse tissues and during in vitro differentiation of embryocarcinoma PCC4, mouse neuroblastoma Neuro2A and NB41A3 cells in the presence of retinoic acid (RA) or 1% DMSO. oct-2 mRNA is characterized by a complex pattern and exists in both poly(A)+ and poly(A)- forms. oct-2 mRNA was found in many cell lines, whereas Oct-2 protein was detected only in some of these cells. oct-2 expression also changed during cell differentiation. The cell differentiation is likely to be controlled not only at the gene transcription level, but also at the level of regulation of nuclear transcription factor activity. Such a regulatory mechanism would provide for a finer regulation of cell differentiation.
Assuntos
Proteínas de Ligação a DNA/biossíntese , RNA/biossíntese , Fatores de Transcrição/biossíntese , Animais , Sequência de Bases , Diferenciação Celular/genética , Sondas de DNA , Proteínas de Ligação a DNA/genética , Camundongos , Dados de Sequência Molecular , Fator 2 de Transcrição de Octâmero , Fatores de Transcrição/genética , Células Tumorais CultivadasRESUMO
The expression of an Oct-binding protein Oct-2 was studied during differentiation of three cell lines. Two inductors were used in our experiments: retinoic acid and DMSO. It was shown that all these cells have heterogeneous population of Oct-2 mRNA. Under differentiation the pattern of Oct-2 RNA and expression of active Oct-2 proteins was changed.
