Substrates, for cell attachment

Several cell culture studies demonstrated that scaffolds made via self-assembling peptides provide permissive substrates for cell attachment and growth as well as support for extensive neurite outgrowth and synapse formation [104-106],... 

A variety of substrate- and cell-attached factors influence neural development by regulating adhesion properties of cells (see Ch. 7). Interactions occur directly between cells or between a cell and the extracellular matrix (see Ch. 2). The molecules mediating these interactions have been implicated in regulating the specificity and timing of cell-cell adhesion and the consequences on cell morphology and physiology. Hence, they influence the ability of cells not only to migrate but to sort themselves out and to stabilize spatial relationships considered important for the process of differentiation. 

In tissue engineering these stmctures are called scaffolds and serve a number of functions induding (1) maintaining the shape of the new tissue to be formed ( an ear should be shaped like an ear ), (2) matching the mechanical properties of the tissue, (3) providing an adhesive substrate for cells to attach and proliferate, and (4) delivering signals and molecules for... 

FIGURE 12.12 Schematic of mouse embryonic stem cells (mESC) attachment (above LCST) and detachment (below LCST) to/from thermo-responsive polymer substrates. Poly(ME02MA-co-OEGMA) polymer brushes are shown as chain extended at temperatures below the LCST forming a cell-resistant surface, whereas collapse of the bmshes above the LCST results in a more favorable surface for cell attachment [192]. 

PHA solutions of various densities were used to prepare transparent flexible films. The surface properties of PHB and P(HB-co-HV) fllm scaffolds were similar to each other and to those of synthetic polyesters (polyethylene terephthalate, poly (methyl methacrylate), polyvinyl chloride, and polyethylene) (Shishatskaya 2(X)7X The scaffold s surface properties are important for cell attachment and proliferation. To enhance cell adhesion to the surface, improve the gas-dynamic properties of scaffolds, and increase their permeability for substrates and cell metabolites, the scaffolds can be treated by physical factors or by chemical reagents. Biocompatibility of PHA scaffolds has been enhanced by immobilizing collagen fllm matrices on the scaffold surface and coating with chitosan and chitosan/polysaccharides (Hu et al. 2003). 

The ability of the films to support cell adhesion was evaluated by using the film as a substrate for cell growth. Films were placed into wells and coated with a cell rich solution. After seven days, all films were microscopically and histopathologically examined. Some of the results obtained are shown in Figures 4 a-d. Both the PLA and PCL films had complete monolayers on their surfaces comparable to the control. The CH film had either sparse, rounded cells or no cells present. The work by Albanese had determined that cells could not attach themselves to substrates such as EO-sterilized CH. This substrate changed the shape of the cells from the usual elongated cylindrical fibroblast form, to a rounded form and the cells then remained in suspension (34). The y-irradiated chitosan film also showed the same behavior. 

Previous sections have dealt with the production of supported bioassemblies by transfer of precast constructs to solid supports, by structured assembly on functionalized surfaces, or by nonstructured incorporation into polymeric films. An intriguing avenue to the realization of structured nanoscale biocatalytic films is the utilization of crystalline bacterial cell surface layers (S layers or crystallines) as preorganized and functionalized substrates for biomolecule attachment [147-151]. 

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