Directed self-assembly of large scaffold-free multi-cellular honeycomb structures

Abstract

A significant challenge to the field of biofabrication is the rapid construction of large three dimensional (3D) living tissues and organs. Multi-cellular spheroids have been used as building blocks. In this paper, we create large multi-cellular honeycomb building blocks using directed self-assembly, whereby cell-to-cell adhesion, in the context of the shape and obstacles of a micromold, drives the formation of a 3D structure. Computer aided design, rapid prototyping and replica molding were used to fabricate honeycomb-shaped micro-molds. Nonadhesive hydrogels cast from these micro-molds were equilibrated in cell culture medium and seeded with two types of mammalian cells. The cells settled into the honeycomb recess, were unable to attach to the nonadhesive hydrogel and so cell-to-cell adhesion drove the self-assembly of a large multicellular honeycomb within 24 hours. Distinct morphological changes occurred to the honeycomb and its cells indicating the presence of significant cell-mediated tension. Unlike the spheroid, whose size is constrained by a critical diffusion distance needed to maintain cell viability, the overall size of the honeycomb is not limited. The rapid production of the honeycomb building unit, with its multiple rings of high density cells and open lumen spaces, offers interesting new possibilities for biofabrication strategies.

Bioinspired engineering of honeycomb structure – Using nature to inspire human innovation

“…For instance, numerous examples of hexagonal or similar patterns have been found in living tissue [14,33,34], cell aggregates [35] and molecules [36]. In the past several decades, with advances in manufacture technologies, honeycomb structures have been adapted into different applications, ranging from engineering [37][38][39][40][41][42] to more recently biomedicine [43][44][45], accumulating a rich store of artificial honeycomb structures at scales varying from macrometer to nanometer. In Fig.…”

Dissecting the stem cell niche with organoid models: an engineering-based approach

“…and stage. Theoretically, small organoids themselves can also be used as a printable ink, allowing higher-order structures to be printed (Livoti and Morgan, 2010;Rago et al, 2009;Tejavibulya et al, 2011). These and related 3D printing platforms, although still limited in their number of applications in the study of the stem cell niche, will ultimately provide increased control over tissue architecture spanning multiple length scales -a major challenge for directing the growth of tissues and organoids.…”

Three-Dimensional Cell Culture Models for Biomarker Discoveries and Cancer Research

“…Thus, it is sometimes appropriate to consider spheroids as 3D culture models for cancer biomarker projects. As a 3D model, spheroids have become a useful tool for recreating the 3D tumor microenvironment in the absence of external scaffolding [30].…”

“…Thus, it is sometimes appropriate to consider spheroids as 3D culture models for cancer biomarker projects. As a 3D model, spheroids have become a useful tool for recreating the 3D tumor microenvironment in the absence of external scaffolding [30].Cell spheroids are usually generated using the hanging drop method [31], by shaking cell suspensions with continuous motion [32], or by the traditional soft-agar method [33]. All of these methods partly represent 3D conditions in vivo because they allow anchorageindependent cellular aggregation.…”