I’d like to share the review about principles of cellular self-assembly and bioprinting in scaffoldless tissue engineering. This is the best review that I know on the topic.
Self-assembly is the autonomous organization of components, from an initial state into a final pattern or structure without external intervention.
Ultimately, the success of engineering and fabricating functional living structures will depend on understanding the principles of cellular self-assembly and our ability to employ them.
Cellular self-assembly approaches represent an alternative and offer a complement to scaffold-based tissue engineering. They allow establishing high cell density, controlled deposition of extracellular matrix and positional specificity of cell patterning. Translation of cell and tissue self-assembly approaches into the clinical field will necessarily depend on our ability to understand the principles underlying such approaches.
Advantages of bioprinting:
…the novel print-based tissue-engineering technology has several distinct features with great potential for the generation of tissue and organ structures: (i) it represents an approach for producing fully biological (scaffold-free) small diameter vessels; (ii) it utilizes natural shape-forming (i.e. morphogenetic) processes, that are present during normal development; (iii) it can provide organoids of complex topology (i.e. branching tubes) and (iv) it is scalable and compatible with methods of rapid prototyping.
Overall, a largely empirical approach to tissue engineering (â€˜tissue try thisâ€™, as cleverly described by Shannon Dahl) is being replaced by the development of developmentally inspired technologies (approaches based on bioprinting and self-assembly being remarkable examples). Consequently, one major focus is on the cells. With the living cell being the ultimate â€˜tissue engineerâ€™, our effort is being directed to providing the conditions, so that the cells do the engineering. Another focus is on technology. After major breakthroughs in stem cell biology, we are now developing technologies for â€˜instructingâ€™ the cells to regenerate defective tissues by providing a highly engineered environment.
These focus points are illustrations of the paradigm shift in the field toward the establishment of a â€˜biomimeticâ€™ approach, that is based on the premise that unlocking the full biological potential of stem cells (in vitro or in vivo) necessitates an environment similar to that present during native development. This paradigm is guiding many current tissue-engineering approaches, including those based on cell self-assembly that holds promise of building fully biological tissues with structural and functional specification.