Scaffoldings, temporary functional

In such temporary functional scaffoldings, natural cells can be induced into the scaffold, attached, and stretched due to the pulsing blood as a consequence, cells remodel the synthetic scaffold into a natural tissue sufficient to sustain essential mechanical function. 

Thus, the potential exists for preparing bioelastic matrices that match the deformable properties of the tissue to be reconstructed, and the potential exists for the matrix to be a temporary functional scaffolding into which the natural cells migrate and attach. There the cells sense the forces that the tissue must sustain and begin reconstructing the appropriate natural tissue. 

A few examples are discussed in Chapter 9 wherein the future will see the biosynthesis of biodegradable protein-based thermoplastics, materials to prevent postsurgical adhesions, temporary functional scaffoldings to direct tissue reconstruction, and drug delivery devices for new drug release regimens. 

In the words of E.O. Wilson in 1998, To the extent that we depend on prosthetic devices to keep ourselves and the biosphere alive, we will render everything fragile. The consilient approach to tissue engineering utilizes biology s own materials and mechanisms, concerned with tissue structure and function, to achieve tissue restoration. It is made possible by temporary functional scaffoldings composed of biodegradable and biocompatible elastic model proteins that are responsive to tissue variables in the same manner as natural proteins. 

Tlie materials are fashioned into temporary functional scaffoldings into which the natural cells can migrate, attach, spread, and sense the forces to which the temporary functional scaffolding is subjected, andl the cells in response turn on the genes to produce an extracellular matrix sufficient to sustain those forces. Thereby the natural cells remodel the temporary functional scaffolding into a natural tissue. 

Elastic protein-based polymers have been designed both to provide cell attachment sites and to exhibit the required elastic modulus of the tissue to be replaced. Thus, this introduces the potential to design temporary functional scaffoldings with the capacity to be remodeled, while functioning, into a natural tissue by the natural cells of the tissue. 

Figure 9.21 exemplifies the nexus between cellular mechano-chemical transduction and elastic protein-based polymers containing cell attachment sequences that enables these temporary functional scaffoldings to result in restoration of natural tissue. Figure 9.21 A shows in the absence of cell attachment sequences that the elastic matrix X -poly(GVGVP) does not support attachment of cells. On inclusion of cell...

Figure 9.21. Cellular mechanochemical transduction makes possible tissue restoration by elastic protein materials containing cell attachment sequences that function as temporary functional scaffoldings. The attached cells become stretched as the matrix is stretched. The forces and frequencies of the stretch/relaxation cycles provide the chemical signal to the nucleus to turn on the genes for production of an extracellular matrix sufficient to...

Temporary Functional Scaffoldings for Soft Tissue Restoration... 

Whenever a dynamic structure fails or is so diseased that it needs to be replaced, the concept of temporary functional scaffoldings comes into play. Examples are synthetic arteries, urinary bladder, intervertebral discs, and even a temporary functional scaffolding for skin replacement, for example, after burns. 

Each of these structures begins with a structural integrity and a dynamic functional range that becomes lost through any number of disease processes. In each of these cases and many others, the concept of a temporary functional scaffolding couples with the remodeling capacity of natural cells sensing the demands of a normal tissue environment to result in tissue... 

Polymer hydrogels consist of a cross-finked network of hydrophilic polymers with a very large water content (up to 99%) (Wichterle and Lim, 1960).They are structurally similar to the ECM and have therefore frequently been used as ECM mimics (Fedorovich et al., 2007 Shoichet, 2010). Other biological applications include the use as injectable scaffolds, (temporary) cell culture supports and drug delivery matrices (Mano, 2008). For all these applications, the introduction of enzyme-responsive functionalities into the polymer hydrogel is attractive because it would either more closely mimic the ECM (which is itself enzyme responsive) or allow drug delivery in response to the presence of a specific enzyme. 

This chapter will review current activities and proposed research related to the development of artificial organs and organ-assist devices. While we will focus on the human liver, the discussion is applicable to other organs. The pancreas and the endocrine functions of the kidney follow the same basic path — the culturing of cells on a scaffold. The cells, of course, must function as they do in a natural uncompromised slate while the scaffold provides a permanent or temporary template on which the cells attach and proliferate. 

Nanofibrous structures have been extensively smdied as the two- or three-dimensional scaffolds that mimic the cell living environment for tissue regeneration. Nanofibrous structures provide temporary spaces with a mnable porosity in which cells can exchange metabolites and nutrients with their environment so that cellular functionality can be maintained, the reconstruction of tissues can be aided, and the tailored mechanical properties will function as desired, and the wound bed can be protected from collapsing, and mechanical mismatch between scaffolds and host tissues can... 

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