Fabrication Of Channeled Tissues By Assembling Microtissues Through Perfusion Culture

To build a prevascularized tissue-engineered construct, which is supposed to address the issue of mass transport limit encountered in tissue engineering, we have proposed a microfabrication reassembly strategy based on the pre-feasibility study of fabricating multichannel construct in vitro. In this study, we assembled microtissues to form the single-channeled construct through perfusion culture using the microfabrication reassembly strategy, and further realized the operating parameters’ effects on the process of the fabrication and the channeled constructs themselves, which offering the essential data on endothelialization of the channels and construction of the prevascularized engineered tissue.We used microtissue as building block to build the single-channeled construct, namely tubular tissue through perfusion culture. The initial stacking density of microtissues and culture time were examined to better understand their effects on cellular metabolism during the culture time or the properties of the constructing tubular tissue after the perfusion culture such as morphology, distribution of cells and ECM. The results showed that tubular tissues fabricated by random-packing microtissues possessed an integrate structure with good mechanical properties. However, some microtissues were leaked from random-packing construct and the structure of the construct would be destroyed. Different initial stacking density of microtissues affected the void ratio of the construct. Compared to the constructing tubular tissues with an initial stacking density of22mg/cm3or44mg/cm3, the tubular tissue with an initial stacking density of30mg/cm3had an integrated structure with superior cell viability and uniform cell distribution, and a certain amount of ECM. Compared to the building tubular tissues cultured for10days or23days, the tubular tissue cultured for14days had higher cell viability and ECM content with two thick strata in the inner and outer regions of the construct. However, the tubular tissue with10days perfusion culture showed a loose structure, and cell viability and ECM distribution were much more heterogeneous when the culture time was extended to23days.Collectively, by using the microfabrication reassembly technology, we were able to fabricate a tubular tissue with integrated structure, good mechanical and compressive properties, and uniform distribution of cells and ECM by optimizing the microtissues’ packing pattern and culture time.