Multifarious Fabrication Approaches of Producing Aligned Collagen Scaffolds for Tissue Engineering Applications

Aligned tissue architecture is a basic proviso for several organs and tissues like intervertebral discs, tendons, ligaments, muscles, and neurons, which comprises type-I collagen as an eminent extracellular matrix (ECM) protein. Exploiting type-I collagen for the biofabrication of aligned constructs via different approaches is becoming apparent, as it comprises a major fraction of connective tissue, exhibits abundance in ECM, and displays poor antigenicity and immunogenicity, along-with the ease of remodelling adaptability. Collagen hydrogels or composite scaffolds with uniaxial fibril alignment or unidirectional pore architecture having different sizes and densities are being fabricated using electrical, mechanical, and freeze-drying processes which are applicable for tissue engineering and regenerative purposes. This review focuses on several multifarious approaches employed to fabricate anisotropic structures of type-I collagen which influences fibril alignment, pore architecture, stiffness anisotropy, and enhanced mechanical strength and mimics the tissue native microenvironment ushering cell niches to proliferate and differentiate into tissue specific lineages.