Design, evaluation and biofabrication of scaffolds in PLA

• Grant number: 14/17081-6
• Support Opportunities: Scholarships abroad - Research
• Start date: November 15, 2014
• End date: December 04, 2014
• Field of knowledge: Engineering - Chemical Engineering - Chemical Process Industries
• Principal Investigator: André Luiz Jardini Munhoz
• Grantee: André Luiz Jardini Munhoz
• Host Investigator: Paulo Jorge da Silva Bartolo
• Host Institution: Faculdade de Engenharia Química (FEQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Institution abroad: University of Manchester, England

Abstract

Tissue engineering is a multidisciplinary field that requires the combined effort of cell biologists, engineers, material scientists, mathematicians, geneticists, and clinicians towards the development of biological substitutes that restore, maintain, or improve tissue function. Two fundamental strategies can be considered: bottom-up approaches and top-down approaches. The bottom-up approach employs different techniques for creating modular tissues, which are then assembled into engineered tissues with specific micro-architectural features. Tissue modules can be created through self-assembled aggregation, microfabrication of cell-laden hydrogels, fabrication of cell sheets or direct printing. The major drawback of this approach is that some cell types are unable to produce sufficient extracellular matrix (ECM), migrate or form cell-cell junctions. The top-down or scaffold-based approach is based on the use of a temporary scaffold that provides a substrate for implanted cells and a physical support to organize the formation of the new tissue. In this approach, transplanted cells adhere to the scaffold, proliferate, secrete their own ECM and stimulate new tissue formation. This is the most commonly used strategy for tissue engineering and strongly depends on both materials and manufacturing processes. Scaffold-based strategies strongly depend on both materials and manufacturing processes. From a material point of view, four classes of biomaterials have been used for engineering tissues: naturally derived polymeric materials, acellular tissue matrices, synthetic petrochemical-derived polymers and ceramic materials. However, it is quite often impossible to find a single material, which meets all the demands such as biocompatibility, mechanical strength, biodegradability, and promotion of cell-adhesion, proliferation and differentiation. From a fabrication point of view, scaffolds can be produced through a wide range of simple techniques such as solvent casting, phase separation, foaming and electrospinning. However, each of these techniques presents several limitations which usually centre on the lack of effective control of the pore size, pore geometry and spatial distribution of pores, besides being almost unable to construct internal channels within the scaffold. Although the shape and the size of the pores can be varied by changing the parameters of these techniques, the resulting scaffold pore organisation is random. Thus, additive manufacturing (AM) processes, in which physical objects are created from computer-aided generated models, are considered viable alternatives to fabricate scaffolds for tissue engineering as they offer a better control and the ability to actively design the porosity and interconnectivity of scaffolds. When combined with clinical imaging data, these fabrication techniques can be used to produce constructs that are customised to the shape of the defect or injury. However, available AM processes do not provide a perfectly affinitive environment for cells due to the incapacity of providing adequate chemical, physical and biological cues in a tunable and effective way. This project aims to solve some of the abovementioned limitations by exploring a new route to produce and to exploit a novel hybrid biomanufacturing system which allows the scaffold fabrication layer by layer by polymer extrusion. (AU)