Hierarchical engineering of modular tissues

Tissue engineering, aimed at engineering organs, is a compelling and growing field of science with yearly improvements and progress. New technological advancements in material science, stem cell engineering, and fabrication techniques push the field forward with a shared determination to improve human health and well-being. However, the real challenge is the complex architecture of native tissues and its reciprocation in engineered tissues, which hinders the engineering of fully functional tissues. Despite conventional tissue engineering approaches utilizing the combination of modern biomaterials and advanced properties of stem cells, they are still less successful in reciprocating the full functionality of engineered tissues. Hence, this thesis aims to engineer tissues with near-architectural resemblance to native tissues, with hierarchical emergent properties from the single-cell to tissue level. A single-cell pericellular environment is developed using droplet microfluidics, and the mechanics from the matrix are transmitted to the cell by anchoring the matrix directly onto the cell membrane. The established mechanotransduction route determines stem cell fate via intracellular biophysical programming of the cytoplasm and nucleus. The pericellular environment matches the native tissue’s pericellular matrix properties, enabling a functional, living micro building block. These micro building blocks are then used to create an engineered modular tissue by embedding them in a strong and tough interterritorial matrix, compensating for the tissue-level mechanical properties. The interterritorial matrix, is achieved using the properties of immiscible biomaterials in aqueous states (phase separation), forms various architectures that dictate the overall mechanics of the interterritorial matrix. The engineered modular tissue matches native tissue architecture by being soft at the cellular level and strong and tough at the tissue level. This emergent property, achieved via modular design, includes selective diffusion properties between the pericellular and interterritorial matrices. Thus, this modular design favors the concentration of cell-produced factors in the pericellular environment that the cells can use for cellular function. Moreover, it also inhibits the entry of catabolic paracrine factors from the external environment that could induce inflammatory stimulation in the cells. Collectively, this thesis engineered a modular tissue with emergent properties that compensate for the presence of cell- and tissue-level hierarchy present in native tissues.