Scaffolds for Tissue Engineering | Characteristics and Basic Functions of Scaffolds | Applications of Scaffolds

Scaffolds for Tissue Engineering

Mashood Ahmed
Department of TE
University of Management and Technology (UMT)
Lahore, Pakistan

Use of textile structures in a medical field is not recent because sutures, which for centuries have been used for closure of wound or incision, or fundamentally textile structures. Due to recent advancements in textile engineering and bio-medical research the use of textiles in surgery is growing. They are routinely used to supplement or replace the functions of living tissues of the human body. Soft tissue replacement or implants such as vascular graft, skin grafts, hernia patches and artificial ligaments are made of textile filaments. Moreover polymers reinforced with textiles, called polymer composite materials, are also considered in hard tissue replacements, spine rods, intervertebral disks and spin cages.

The scaffolds are three dimensional, porous structures encourage cell attachment, proliferation and migration through an interconnected network of pores. Scaffolds are artificial devices, designed to act as templates for attached cells and newly formed tissues.

What are scaffolds made of?
  • The scaffolds are made up of fibers which are synthetic and natural.
  • Synthetic fibers can be Bio-Degradable and Non-Biodegradable and Natural fibers are Human, Plant, or Plant Tissue.
Fibers Used:
Natural materials: Such as Collagen, Keratin, Silk, Chitin ,Fibroin, Chitosan and Mussel Proteins.

Synthetic materials: The non degradable materials such as Polyethylene, PTFE etc.

Synthetic bio degradable polymer: Such as Polyester, Poly anhydride, Poly Orthoesters, Polyphosphazenes, etc.

Scaffolds for Tissue Engineering:
Cells are isolated from the patient’s 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 patient’s body.

Synthesis of Scaffolds:
A number of different methods have been described for preparing porous structure to be employed as tissue engineering scaffolds.
  • Nanofiber Self-Assembly
  • Solvent Casting & Particulate Leaching (SCPL)
  • Gas Foaming
  • Emulsification/Freeze-drying
  • Thermally Induced Phase Separation (TIPS)
  • Electro spinning
Currently, two methods, phase separation and electro spinning have been used to prepare the nanofiber with diameters ranging from 100 to 900 nm.

Scaffolds Structural Design Parameters:
For a scaffold to function effectively
  • It must possess the optimum structural parameters, conducive to the cellular activities leading to new-tissue formation
  • These include cell penetration and migration into the scaffold, cell attachment onto the scaffold substrate, cell spreading and proliferation and cell orientation. 

Scaffolds Characteristics:
  • Porosity for cell migration
  • Balance between surface hydrophilicity and hydrophobicity for cell attachment
  • Mechanical properties comparable to natural tissue to withstand natural loading conditions
  • Degradation capability so that it gets completely reabsorbed after implantation
  • Nontoxic by products
  • 3D matrix.

Basic Functions of Scaffolds:
Scaffolds Functions
Scaffold Design Parameter
Non inflammatory or non toxicity.

Biocompatible, non-Toxic and non-carcinogenic.
To assist in the growth of 3-d tissue & organs.
3-d scaffold of specific shape.
To promote cell proliferation and migration leading to tissue growth throughout the scaffold.
Optimum pore size to allow for cell penetration, with high porosity & interconnectivity between pores.
To allow for the movement of nutrients and waste in & out of the scaffold.
High porosity and interconnectivity between pores.
The scaffold may degrade to leave only natural tissue.
Rate of degradation to match the rate of tissue formation.
Support for developing tissue.
Scaffold should have mechanical properties of developing tissue.
Applications of Scaffolds:
  1. A knitted Poly(lactic-glycolic acid) scaffold seeded with bone marrow stem cells.
  2. A micro braided tube was successfully used as a nerve guide growth conduit in regenerating a 10mm nerve gap with a 90% success rate.
  3. A multi layer-knitted PGLA and Polycaprolactone co-fiber as also been used for skin tissue generation, Heart valve, Tendons and Ligaments.
  4. A woven polyethyleneterephthalate textile rolled into a cylinder was successfully used for dynamic hepatocyte cell culture.
  5. A composite tube made of braided PGLA coated with a porous PLA-PCL copolymer has been used for blood vessel regeneration, with its elasticity adjusted to mimic the native blood vessel.
  6. Application of electro spun poly(l-lactic) acid nanofibrous scaffold seeded with chondrocytes for cartilage tissue engineering.
  • Scaffolds are a boon to Mankind
  • Textile structure are particularly attractive to tissue engineering because of their ability to tailor a broad spectrum of scaffolds with a wide range of properties.
  • Further systematic study is necessary to design a optimal scaffold for each tissue applications. Textile scaffolds are extreamly versatile and therefore ideal for encouraging cells to recreate tissue geometry.
  • They are easily adapted to meet different cell requirements which will be an emerging trend in Medical Textiles. 


Anonymous said...

Where did you get the image for the scaffold characteristics? and do you have any references, as I am interested in finding out more.

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