Tissue engineering: the biophysical background

Abstract

Tissue engineering is the construction, repair or replacement of damaged or missing tissue in humans and other animals. This engineering may take place within the animal body or as tissue constructs to be made in a bioreactor for later grafting into the animal. The minimal set of materials for this are the appropriate types of cell. Usually, however, non-living substrata are used as well. These substrata may be nothing more than materials that bulk up any voids in the damaged tissue and provide the mechanical strength that has been lost when the tissue is damaged or removed. They may serve a similar pair of functions in the bioreactor. They can do much more in terms of pattern formation. The orientations and morphology of the cells, the arrangement of intercellular material as it is laid down and the relationships between different cell types in the repairing or construct tissue are all of importance, for these should resemble the correct normal tissue as closely as possible. Most of these requirements are ones involving pattern formation. This review discusses the various ways in which tissue pattern can be engineered chiefly from a biophysical standpoint. Unpatterned cells are effectively not tissue. This engineering includes the use of topography on the substrata, chemical patterning of adhesive and other cues for the cells, mechanical force application to cause cell orientation and appropriate synthetic responses and electrical fields. The review also discusses the methods used to impart the appropriate cues to and through the materials which are often biodegradable polymers. The article gives particular attention to regions of research and practice where the involvement of the physicist or biophysicist is of importance.

The interplay between the proteolytic, invasive, and adhesive domains of invadopodia and their roles in cancer invasion

“…120,121 In addition to their mechanical role, integrin adhesions to the ECM act as "multi-sensory" sites, enabling cells to "scan" the ECM, and respond to its chemical-molecular properties, as well its physical characteristics, including rigidity, stretching, [122][123][124][125] and topography of the ECM. [126][127][128][129][130] It is commonly accepted that the spatiotemporally regulated coupling between protrusive processes and the establishment of nearby adhesions is essential for cell locomotion and invasion. 63,131,132 During the migration process, for example, the forward extension of lamellipodia or filopodia, driven by local actin polymerization, is guaranteed by the presence of focal adhesions or focal complexes at the posterior aspects of these protrusions.…”

Cell Growth in Response to Mechanical Stiffness is Affected by Neuron- Astroglia Interactions

“…Among critical extracellular cues, the effects of physical stimuli, including traction force, mechanical strain, surface topography, and in particular, substrate stiffness, have been identified and found to affect cellular behavior in a cell-type specific manner [4][5][6][7]. Wang and co-workers popularized bis-acrylamide crosslinked hydrogels ('bis-gels', hereafter) as substrates to study cell-substrate interaction [8].…”

Tailoring Cell Behavior on Polymers by the Incorporation of Titanium Doped Phosphate Glass Filler

“…Actin, which is a major structural protein, gives information on the general condition of the cells-ability to adhere and spread. [42] Tubulin is another structural protein and is important in cell metabolism as vesicles are moved in and out of the cell (endocytosis and exocytosis) along the tubulin microtubules. [42,43] While vinculin, is a protein involved in cell adhesion and shows contacts of the cells with materials.…”

“…[42] Tubulin is another structural protein and is important in cell metabolism as vesicles are moved in and out of the cell (endocytosis and exocytosis) along the tubulin microtubules. [42,43] While vinculin, is a protein involved in cell adhesion and shows contacts of the cells with materials. [44] These adhesion points are important in cell signaling, proliferation, and differentiation.…”