With gradually increasingly human life expectancy, there is an increasing demand for replacement material to repair defective tissues or diseased organs. Some small animals, like salamanders, lizards and some frogs, could regenerate lost limb or tail, but higher animals like humans can not do this. It is amazing how these animalsí body know which part to regrow, in exactly same shape. In human, cells lack the ability to regrow in previous anatomical shape of the tissue. Instead, they randomly migrate to form a two-dimensional monolayer of cells. They need some cues to reorganize into tissues.
Tissue Engineering is a multidisciplinary field that applies the principles of Biology, Chemistry, Physics and Engineering for the development of substitutes that replace, repair or enhance biological function of diseased and damaged human body parts, by manipulating cells via their extracellular microenvironment. This three dimensional extracellular architecture ("scaffold") can be fabricated in the shape of the tissue we want to restore, with the help of either polymer hydrogel, self-assembly, nonwoven matrix, nano-fibrous electrospun matrices, 3D weaving, or any other textile technology-based techniques, depending upon their structural and functional requirements.
Ideally the scaffolds should regulate cell adhesion, proliferation, expression of a specific phenotype and extracellular matrix deposition in predictable and controlled fashion. Physical structure of scaffold may control cell function by regulating the diffusion of nutrients, waste products and cell-cell interactions by providing spatial and temporal control of biochemical cues, whereas scaffold surface chemistry indirectly affects cell adhesion, morphology and subsequent cellular activity by controlling adsorption of ions, proteins and other molecules from the culture medium.
Basic principle of Tissue engineering is illustrated in the following figure. Cells can be isolated from the patientís body, and expanded in a petridish in laboratory. Once we have enough number of cells, they can be seeded on a polymeric scaffold material, and cultured in vitro in a bioreactor or incubator. When the construct is matured enough, then it can be implanted in the area of defect in patientís body.
During the last decade, Tissue Engineering research has made significant progress towards fabricating human tissue constructs in laboratory. One active area of current research is the combination of tissue engineering principles and knowledge from developmental biology to establish relatively simple in vitro disease model system, to gain insight into mechanisms of disease origins, pathological conditions and to screen novel treatment modalities. The establishment of human cell-based in vitro engineered disease model system could represent a paradigm shift from inadequate conventional monolayer cell cultures, or moderately successful animal models, towards more physiologically tissue-relevant, patient-specific approaches. While these are early days of such inquiry, the potential for impact using this approach is immense.†