The development, use, and challenges of electromechanical tissue stimulation systems

Abstract

Tissues including lung, heart, and bone in the body are subjected to biological, electrical, and mechanical stimulations. These stimulations greatly affect their growth, phenotype, and function, and play an important role in modeling tissue physiology. With the goal of understanding the molecular mechanisms underlying the response of tissues to external stimulations, in vitro models of tissue stimulation have been developed with the hopes of recapitulating in vivo tissue function. Herein we review the efforts to create and validate tissue stimulators responsive to electrical or mechanical stimulation including tensile, compression, torsion, and shear. These bioengineered platforms have designed such that tissues can be subjected to select types of mechanical stimulation from simple uniaxial to humanoid robotic stain through complex equal-biaxial strain. Electrical stimulators have been developed to subject tissues to select electrical signal shapes, amplitudes, and loading cycles were used in tissue development derived from stem cell, maturation of tissue, and regeneration of tissue function. Some stimulators allow for the observation of tissue morphology in real-time while cells undergo stimulation. We also discuss the limitations and challenges in the development of tissue simulators. Despite advances in creating useful tissue stimulators, there remain opportunities for improvements to recreate physiological functions including: replicating complex loading cycles, electrical and mechanical induction combined with biological stimulation, and taking into account the change of strain affected by the applied inputs. We expect that the use of tissue simulator platforms will play an increasingly vital role in tissue modeling, stem cell development, and drug development.