A Glycosaminoglycan Based, Modular Tissue Scaffold System for Rapid Assembly of Perfusable, High Cell Density, Engineered Tissues

Abstract

The limited ability to vascularize and perfuse thick, cell-laden tissue constructs has hindered efforts to engineer complex tissues and organs, including liver, heart and kidney. The emerging field of modular tissue engineering aims to address this limitation by fabricating constructs from the bottom up, with the objective of recreating native tissue architecture and promoting extensive vascularization. In this paper, we report the elements of a simple yet efficient method for fabricating vascularized tissue constructs by fusing biodegradable microcapsules with tunable interior environments. Parenchymal cells of various types, (i.e. trophoblasts, vascular smooth muscle cells, hepatocytes) were suspended in glycosaminoglycan (GAG) solutions (4%/1.5% chondroitin sulfate/carboxymethyl cellulose, or 1.5 wt% hyaluronan) and encapsulated by forming chitosan-GAG polyelectrolyte complex membranes around droplets of the cell suspension. The interior capsule environment could be further tuned by blending collagen with or suspending microcarriers in the GAG solution These capsule modules were seeded externally with vascular endothelial cells (VEC), and subsequently fused into tissue constructs possessing VEC-lined, inter-capsule channels. The microcapsules supported high density growth achieving clinically significant cell densities. Fusion of the endothelialized, capsules generated three dimensional constructs with an embedded network of interconnected channels that enabled long-term perfusion culture of the construct. A prototype, engineered liver tissue, formed by fusion of hepatocyte-containing capsules exhibited urea synthesis rates and albumin synthesis rates comparable to standard collagen sandwich hepatocyte cultures. The capsule based, modular approach described here has the potential to allow rapid assembly of tissue constructs with clinically significant cell densities, uniform cell distribution, and endothelialized, perfusable channels.

Collagen Type II enhances chondrogenic differentiation in agarose-based modular microtissues

“…More broadly, modular approaches to creating engineered tissue are emerging as a promising approach to creating complex structures [71–76]. Such methods have advantages over conventional scaffold-based techniques [64, 72], and new methods are being developed at a rapid rate.…”

Strategies for improving the physiological relevance of human engineered tissues

“…Vasculature can be achieved by creating interconnected, endothelial lined, channels [55–58] or by allowing cells to re-create their own microvasculature [17, 18, 22, 59]. The crosstalk between endothelial cells and perivascular/stromal cells [22] and bulk organ cells such as osteoblasts [17] or hepatocytes [18], can be used to control the formation and function of blood vessels with intact barrier functions and 3D architectures and biochemical markers similar to in vivo vasculature.…”

Characterization of printed PLA scaffolds for bone tissue engineering

“…Another advantage of FDM technology is the ease to associate cells with these thin polymeric scaffolds resulting in a better cell colonization, proliferation and differentiation compared with a larger 3D structure which often includes an inner hypoxic central area, which prevents deep cell colonization. Moreover, stacked together, these populated scaffolds can form a large 3D structure within an internal organization improving both cell communication and cell–material interactions in vitro and in vivo …”