Introduction


Tissueengineering is an interdisciplinary field that applies the principles ofengineering and the life sciences towards the development of biologicalsubstitutes that restore, maintain, or improve tissue function. A surveystates that there were around 98,074 people waiting for transplants in the year2007. It was also found that about 17 people waiting for transplants die everyday. Textiles play a vital role in the field of tissue engineering which havebeen discussed as follows.


Typesof Cells

  • Autologous
  • Allogenic
  • Xenogenic
  • Isogenic
  • Primary
  • Secondary
  • Stem cells


Typesof Tissue

  • Connective
  • Muscle
  • Nervous
  • Epithelial


Stepsinvolved in tissue Engineering


Asa basic fact,


  • Agroup of cells form a tissue
  • Agroup of tissues form an organ
  • Agroup of organs form an organism


Thebasic steps that are essential for tissue engineering are as follows,

       

  • Isolating cells from the Patient
  • ExpansionInvitro,
  • Seeding theexpanded cells on the scaffolds

IsolatingCells from the Patient:


Forreproduction of the cells this part of tissue engineering is very important.The cell is separated out from the organ and it is made sure that the cellwhich is separated out is not infected


ExpansionInvitro:


Invitro (Latin: within glass) refers to studies in experimental biology that areconducted using components of an organism that have been isolated from theirusual biological context in order to permit a more detailed or more convenientanalysis than can be done with whole organisms. These experiments are commonlyreferred to as "test tube experiments".


 

Seeding the Expanded Cells on the Scaffolds:


The cells that have been grown or nurtured using the techniques of tissue engineering are to be fitted into the infected organ by the process of replacing the infected portion.

Cells are often implanted or 'seeded' into an artificial structure capable of supporting three-dimensional tissue formation. These structures are typically called scaffolds.


Scaffolds usually serve at least one of the following purposes:

  • Allow cell attachment and migration
  • Deliver and retain cells and biochemical factors
  • Enable diffusion of vital cell nutrients and expressed products
  • Exert certain mechanical and biological influences to modify the behaviour of the cell phase.



Requirements of Tissues Engineering Scaffold

  • Interconnecting pores
  • Biodegradability
  • Good surface Chemistry- proliferation, migration, differentiation
  • Adequate Mechanical properties
  • Easier fabrication into varies shapes and sizes.

Materials used as Scaffolds


Synthetic Polymers


v     Polylacticacid(PLA),

v     PolyUrethane(PU),

v     Polycaprolactum(PCL),

v     Polylactic Glycolic acid(PLGA),

v     Hydrogels etc., 

 

Natural Polymers

v     Collagen,

v     Alginate,

v     Chitosan etc.,


Benefits of Using Nano Fibrous Scaffolds:


Extracellular matrix (ECM) is the extracellular part of animal tissue which provides structural support to the animal cells in addition to performing various other important functions such as providing support, segregating tissues from one another, and regulating intercellular communication. The ECM regulates a cell's dynamic behavior. ECM is composed of an interlocking mesh of fibrous proteins and glycosaminoglycans (GAGs).Extracellular matrix includes the interstitial matrix and the basement membrane.[1] Interstitial matrix is present between various animal cells (i.e., in the intercellular spaces). Gels of polysaccharides and fibrous proteins fill the interstitial space and act as a compression buffer against the stress placed on the ECM.[2] Basement membranes are sheet-like depositions of ECM on which various epithelial cells rest.



Formation of the extracellular matrix is essential for processes like growth, wound healing and fibrosis. Natural ECM (Extra cellular Matrices) Consists of nanoscale components such as collagen. Cells in the body are present in n unique environment which is regulated by cell-cell, cell-ECM and cell-soluble factors. In order to provide proper function and organization of native tissues in tissue engineering it is important in mimic tissue properties at nanoscale.


The scaffolds made up of nanofibrous materials resemble and functions as same as the natural ECM .It provides greater surface to volume ratio. The absorption is 2.6-3.9 times more than the solid walled and micro fibrous scaffolds

Manufacture of Scaffolds

  • Electro spinning
  • Self assembly
  • Phase separation


Out of these the electro spinning process is one of the mostly used because of the following advantages,

  • High surface area and porosity
  • Controls the thickness and composition along porosity
  • 50mm to 500mm can be produced by applying electric potential
  •  Mimic the native ECM with nanoscale properties
  •  Supports wide variety of Human cells.
  • Cells attached to nanofibrous scaffolds spread and attach on Multiple Fibre but in case of micro fibrous scaffolds cells were rounded in shape and non proliferative.


References:

  • www.wikipedia.org
  • Ref: Langer and J. Vacanti Tissue Engineering. Science 260: 9
  • Tissue Engineering Wikipedia, Nanofibres and their application in tissue engineering
  • Replicating natures design principles-Twig Mowatt
  • Nanofibres and their applications in Tissue engineering
  • Nanoparticles and their uses in Textiles
  • Nano structure Polymer scaffolds for Tissue Engineering and Regenerative Medicine
  • NanoBiotechnology in Drug delivery and Tissue Engineering