Challenges in tissue engineering

Abstract

Almost 30 years have passed since a term 'tissue engineering' was created to represent a new concept that focuses on regeneration of neotissues from cells with the support of biomaterials and growth factors. This interdisciplinary engineering has attracted much attention as a new therapeutic means that may overcome the drawbacks involved in the current artificial organs and organ transplantation that have been also aiming at replacing lost or severely damaged tissues or organs. However, the tissues regenerated by this tissue engineering and widely applied to patients are still very limited, including skin, bone, cartilage, capillary and periodontal tissues. What are the reasons for such slow advances in clinical applications of tissue engineering? This article gives the brief overview on the current tissue engineering, covering the fundamentals and applications. The fundamentals of tissue engineering involve the cell sources, scaffolds for cell expansion and differentiation and carriers for growth factors. Animal and human trials are the major part of the applications. Based on these results, some critical problems to be resolved for the advances of tissue engineering are addressed from the engineering point of view, emphasizing the close collaboration between medical doctors and biomaterials scientists.

Tissue engineering and the intervertebral disc: the challenges

“…The scaffold can have a variety of roles such as to help retain the cells in the desired location, to provide mechanical properties (sufficient for weight bearing as the disc is always loaded) and/or biochemical cues to the tissue as it is developing or to facilitate and guide tissue ingrowth [45].…”

Stromal-Cell-Derived Extracellular Matrix Promotes the Proliferation and Retains the Osteogenic Differentiation Capacity of Mesenchymal Stem Cells on Three-Dimensional Scaffolds

“…The scaffold functions as the in vivo ECM by providing structural and functional microenvironment (i.e., ''niche'') for cell growth, migration, and differentiation. [9][10][11][12] Although the composition of ECM environment is unique to each tissue, the major components of ECMs are collagens, fibronectin, laminin, and various types of glycoaminoglycans and proteoglycans. 13 ECM, together with growth factors, cytokines, and interactions with other cell types, renders the biological and physical cues that dictate MSC function and overall fate.…”

Binding and Release Characteristics of Insulin-Like Growth Factor-1 from a Collagen–Glycosaminoglycan Scaffold

“…10 Growth factors are soluble proteins that stimulate cell proliferation and differentiation and can be used to aid cell migration, increase cell numbers, and increase matrix production. 2,8,11 Injected growth factors have very short halflives in vivo as they are rapidly dispersed by diffusion or digested by enzymes; hence, they require a delivery device to protect the growth factor from proteolysis until it is released. 1,8,12 To this end, the scaffold could be used to reversibly bind growth factors, confine their release to the defect location to limit any possible side effects, and ensure that their bioactivity is maintained when released.…”

“…1,7,8 Scaffold microstructure, which can be characterized by porosity, mean pore size, interconnectivity, and specific surface area, significantly affects cell adhesion and proliferation. 9 Ideally, the scaffold should also mimic cell-ECM interactions and provide adequate signals to cells via the ECM and growth factors to induce or maintain a desired state of cell differentiation to aid tissue regeneration.…”