Tissue scaffolds play a vital role in tissue engineering by providing a native tissue-mimicking environment for cell proliferation and differentiation as well as tissue regeneration. Fabrication of tissue scaffolds has been drawing increasing research attention and a number of fabrication techniques have been developed. To better mimic the microenvironment of native tissues, novel techniques have emerged in recent years to encapsulate cells into the engineered scaffolds during the scaffold fabrication process. Among them, bio-Rapid-Prototyping (bioRP) techniques, by which scaffolds with encapsulated cells can be fabricated with controlled internal microstructure and external shape, shows significant promise. It is noted in the bioRP processes, cells may be continuously subjected to environmental stresses such as mechanical, electrical forces and laser exposure. If the stress is greater than a certain level, the cell membrane may be ruptured, leading to the so-called process-induced cell damage. This paper reviews various cell encapsulation techniques for tissue scaffold fabrication, with emphasis on the bioRP technologies and their technical features. To understand the process-induced cell damage in the bioRP processes, this paper also surveys the cell damage mechanisms under different stresses. The process-induced cell damage models are also examined to provide a cue to the cell viability preservation in the fabrication process. Discussions on further improvements of bioRP technologies are given and ongoing research into mechanical cell damage mechanism are also suggested in this review.
Economical rapid-prototyping of aspherical lenses
