Desktop Robot Based Rapid Prototyping System: An Advanced Extrusion Based Processing of Biopolymers into 3D Tissue Engineering Scaffolds

Abstract

The loss or failure of an organ or tissue is one of the most frequent, devastating and costly problems in healthcare services. Current treatment modalities for diseased or damaged organs include transplantation, surgical reconstruction, use of mechanical devices, or supplementation of metabolic products However, these therapies remain insufficient due to lack of donors and regaining functionality of the reconstructed organs. Tissue engineering is an interdisciplinary field that brings together the principles of life sciences, medicine and engineering to develop functional artificial tissues to maintain, improve or replace lost or damaged tissue/organ This technology produces physiologic 'replacement parts' for impaired tissues or organs which restore, maintain or improve the function of patient's tissues The implantation of engineered biological substitute will be functional either at the time of implantation, or integrate and form the expected functional tissue at a later stage Tissue engineering requires a mechanically stable, biocompatible, and biodegradable scaffold that allows cell adhesion and proliferation, permits preservation of cell specific properties, and suitable for surgical implantations Therefore, fabricated scaffold should mimic the biomechanical properties of the organ or tissue to be replaced as closely as possible. To meet such requirements, development of appropriate 3D scaffold for tissue construction remains a great challenge in various tissue engineering areas. There are specific shortcomings on developing different types of tissue engineering scaffolds. For example, current scaffolds for skin tissue engineering are not ideal because they are unable to provide optimal environment for cell adherence, proliferation, and multiplication Bone tissue has the capacity of self reconstruction upon injury. However, when the defect is remarkably large it usually remains unrepaired and requires an ideal filler, such as cadaver bone, coral, hydroxyapatite or similar mineral compounds Nevertheless, cartilage always has poor cell density and lack of vascularisations that make the cartilage difficult to be repaired, and leads to the use of an appropriate scaffold Three general strategies have been recommended for developing new tissue They are as follows: 1. Isolated cells or cell substitutes: This approach avoids the complications of surgery, allows replacement of only those cells that supply the needed function, and permits manipulation of cells before infusion. However, its potential limitations include the failure of infused cells to maintain their functionality in the recipient, and immunological rejection. 2. Tissue-inducing substances: The success of this approach depends on the purification and large-scale production of appropriate signal molecules, such as growth factors, and in many cases, the development of methods to deliver these molecules to their targets. 3. Cells placed on or within matrices: In closed systems, the cells are isolated from the body by a membrane that allows permeation of nutrients and wastes but prevents large entities such as antibodies or immune cells from destroying the transplant. These systems can be implanted or used as extracorporeal devices. In open systems, cells attached to matrices are implanted and incorporated into the body. The matrices are fashioned from natural or synthetic polymers.