New perspectives for articular cartilage repair treatment through tissue engineering: A contemporary review

Table 2 Overview of advantages and disadvantages of various scaffolds

Scaffold	Advantages	Disadvantages
Porous scaffolds	High porosity	Use of highly toxic solvent
	Interconnected structure	Low pore interconnectivity
	Simple and easy to manufacture	Difficulty in homogenous cell seeding post scaffold fabrication
		Highly porous scaffolds can have weak mechanical properties
		Lack of control over scaffold thickness
Fibrous scaffolds	Fiber meshes and fiber bonding are simple techniques	Fiber meshes lack mechanical integrity
	Large surface area-volume ratio	Fiber bonding lacks control over porosity and pore size
	High inter-fiber distances for nutrition and gas exchange	Small pore sizes produced during fabrication processes such as electrospinning limit cell infiltration and 3-D cellular integration with host tissue after implantation
Hydrogels	Can form stable and highly ordered scaffolds using self assembly
	Tissue like flexibility	Higher cost
	Viscoelasticity	Non-adherent and usually need to be secured by a secondary dressing, for in-vivo testing
Custom scaffolds (Computer-aided design technique)	Intestinal flow and diffusive transport	Natural polymer hydrogels like collagen gelatin, alginate and agarose may evoke inflammatory responses
	Controlled matrix architecture: size, shape, interconnectivity, branching, geometry and orientation	Low resolution of current systems
	Can control pore and pore size	Selective polymeric materials can only be used
	Controlled mechanical properties and degradation kinetics
Microspheres	Reproducible architecture and compositional variations
	Used as cell carriers, when fabricated using biodegradable and non-toxic materials	Difficult to remove once injected or implanted
	Large surface area for cell attachment and growth	Unknown toxicity associated with microsphere/beads
Native/Extracellular matrix scaffolds	Applicable for 3-D cell culture in a stirred suspension bioreactor Simulates the cell's natural microenvironment in terms of composition, bioactive signal and mechanical properties	Difficult to control degree of decellularization and retain all ECM
		Non-uniform distribution of cells
		Immunogenicity upon incomplete decellularization