Question

1. To regenerate the following tissues/organs, propose a material that can be used for the scaffold and the fabrication method. Briefly justify your selection. (1) Skin Geefor Pahicatnay Sold reekn Cony les 30 stuctre maternal (2) Blood vessel PLA d PLGA moan 4uperstautine nga (3) Kidney phae saation- pLAd PLGA oans why ? (4) Bone PGA PLGA Fiber bordng (5) Tendon comprenpon maldiay-PLA &PLGA ooms hy

Answer 1

1.. There are several scaffold types, such as porous, fibrous, microsphere, hydrogel, composite and acellular, etc., with discrete advantages and disadvantages. These scaffolds are either made up of highly biocompatible natural biomaterials, such as collagen, chitosan, etc., or synthetic materials, such as polycaprolactone (PCL), and poly-ethylene-glycol (PEG), etc. Composite scaffolds, which are a combination of natural or synthetic biomaterials, are highly biocompatible with improved tensile strength for effective skin tissue regeneration. scaffolds will accelerate the production of suitable scaffolds for skin tissue regeneration applications. At the same time, emphasis on some of the leading challenges in the field of skin tissue engineering, such as cell interaction with scaffolds, faster cellular proliferation/differentiation, and vascularization of engineered tissues, is inevitable. In this review, we discuss various types of scaffolding approaches and biomaterials used in the field of skin tissue engineering and more importantly their future prospects in skin tissue regeneration efforts.

2.The ring open polymerisation of lactide results in polylactide which is a chiral molecule that exist in two forms D-PLA and L-PLA. It is a biodegradable thermoplastic polyester. Poly(L-lactide) (PLLA) is a semicrystalline polymer (∼37%) and Poly(DL-lactide) is an amorphous polymer, due to the random distribution of L- and D-lactide units.The hydrolytic product of PLLA is lactic acid which is further catabolized in the lactic acid cycle into water and carbon dioxide.ompared to PGA, the methylated PLA is more hydrophobic and thus degrades slowly.7The copolymer poly(lactic-co-[glycolic acid]) (PLGA) made tubular construct showed appreciable SMC adherence and confluent EC luminal layer formation. The good tensile strength and limited deformation are highly attractive features of PLLA. But the modulus value of 5 GPa is higher when compared to a native vessel. Surface modified PLLA with grafted fibronectin showed improved EC growth but lacked confluence. A 6 month evaluation of a PLGA-collagen scaffold seeded with SMCs and ECs implanted in canine pulmonary trunk showed no thrombus formation for 2 days. The histological analysis revealed an EC monolayer and parallel arrangement of SMCs after 2 months and finally adequate collagen and elastin matrix formation., Electrospun PLA showed less fibrotic reaction and less cellular infiltration but included the presence of giant cells. Dual layered electrospun PLGA seeded with vascular cells differentiated from dog bone marrow with internal diameter of 5 mm, when implanted as an artery substitute for 3 weeks in an adult dog model, showed appreciable patency. In vivo implantation of porous film of PLGA showed cellular organization similar to a native vessel.

3 .artificial scaffolds of porous materials have been widely studied for their ability to enhance tissue regeneration, but commonly used polyester scaffolds such as poly(lactic-co-glycolic acid) (PLGA) release acidic byproducts as they degrade, which can have the opposite effect. The authors therefore seek to optimize these scaffolds, drawing inspiration from two examples of well-studied biology: the ability of magnesium hydroxide to moderate stomach acidity in antacid formulations, and the ability of extracellular matrix preparations to suppress immune responses and promote healing. Note that magnesium hydroxide has already been used in tissue engineering scaffolds, for example.Following these examples, modified scaffolds containing particles of magnesium hydroxide, porcine extracellular matrix (ECM), or a mixture of the two are combined with PLGA.

4.PGA and PLGA by fibre bonding

5.novel tendon scaffold, which reconciled the need for a high-strength, highly manipulatable material, while retaining microtopographical features and microarchitectural structures that were appropriate for tendon regeneration. The scaffold comprised two distinct portions: the core and the shell. The core portion consisted of a series of longitudinally aligned electrospun nanofibers, arranged concentrically in a multilayered core. The core was wrapped by a single-layer shell, consisting of a hollow, perforated tube. The perforations were elliptical in shape, elongated longitudinally. By using axial drawing, the scaffold could be fabricated in a simple and scalable manner while having topological (surface ridges and grooves) and microarchitectural (elongated pores and aligned fibers) features appropriate for tendon tissue regeneration. Simultaneously, the polymeric material underwent strain-strengthening, producing a structure with high tensile stiffness.