Characterization of the real-time mechanobiology of engineered tissue equivalents

Abstract

Engineering functional blood vessels play an important role in both tissue regeneration and wound healing. However, engineered blood vessel equivalent remains to be far from clinical realization due to the difficulty in reconstituting the complex three-layer capillary histology. Among all major challenges, the elucidation on the intricate mechanisms involved in tissue morphogenesis of functional blood vessels engineering in vivo significantly hinders the development of engineered blood vessel equivalent in vitro. Thus the search for a highly biocompatible material for vascular tissue culture is inevitable in the design of artificial blood vessel. During the past several decades, novel biomaterial scaffold for cell attachment and culture have been developed for applications in tissue engineering, biosensing and regeneration medicine. In order to engineer functional blood vessels, it is essential to recapitulate the characteristics of the tunica media consisted of vascular smooth muscle cells (SMCs) which is known to be critical for triggering vasoconstriction and vasodilatation in circulatory system. To simulate the physiological functions of blood vessel, the establishment of hyperplasticity of SMCs in vitro has been focused in several previous studies to produce viable synthetic SMCs in the initial stage and develop into quiescent contractile SMCs with highly aligned orientation by the use of microchannel arrays. However, the mechanism of such hyperplastic transformation occurring inside a microchannel to produce highly regulated orientation and phenotype of SMCs sheet remained to be elucidated. Complex mechanotransduction between cells and the surrounding microenvironment such as the neighboring cells, the extracellular matrix (ECM) and biomaterial scaffold, plays an important role in the regulation of various physiological processes. Among these interactions, cell traction force (CTF) is a crucial representative parameter in cellular functions. The conventional traction force assay for single cell measurement was extended herein for applications in three dimensional cell aggregates. Generally, the cooperative multiple cell-cell and cell-microwall interactions were accessed quantitatively by the newly developed assay with the aid of finite element modeling. Therefore, the main objective of my thesis is to develop different types of micropatterned cell culture platforms for carrying new cell-microenvironment mechanotransduction study in-vitro. At the same time, conventional cell traction force microscopy (CTFM) has been further developed for executing biophysical study of collective SMCs grown in the micropatterned scaffolds as mentioned above. In tissue regeneration, the geometrical and mechanical properties of the microenvironment surrounding cells play an important role in cell physiology including migration, proliferation, differentiation and apoptosis. To mimic physiological conditions in-vivo, micropatterning of cells by applying soft lithography provides new possibilities for conducting experimental…