(188dd) Development of 3D Culture Systems Requiring No Extrinsic Gas Exchange

Development
of 3D culture systems requiring no extrinsic gas exchange

Julia
Lin¹, Clayton Jeffryes^1,*

¹Nanobiomaterials
and Bioprocessing Laboratory (NABLAB), Dan F. Smith Department of Chemical
Engineering, Lamar University, Beaumont, TX 77710

*Corresponding
Author: cjeffryes@lamar.edu

An emerging topic in tissue engineering is the use of
mixed trophic or “chimeric” culture systems to create living, 3-dimensional
tissue cultures that more adequately represent the metabolic rate and cell-cell
interactions of tissues inside the body when compared to conventional artificial
2-dimensional tissue systems. In the
absence of a vascular system, 3-dimensional tissues rely on gas diffusion to
supply oxygen and remove carbon dioxide from within the matrix. This leads to
hypoxic conditions and a loss of cell viability in artificial tissue constructs
at length scales above 120 microns. To overcome this diffusion limitation,
phototrophic organisms, such as algae, are being co-cultured within these
tissues to produce oxygen for the heterotrophic culture while simultaneously
consuming the carbon dioxide byproduct. This symbiotic exchange takes place at
the microscale, thus overcoming any diffusion limitation effects. 
In this study, a mathematical model was developed to describe the oxygen
exchange in chimeric cultures by characterizing the metabolic rates of two
algae species, Synechoccus elongatus and
Spirulina platensis. The viability
and net oxygen production rates of the phototroph-heterotroph cell consortia in
solution and within an encapsulation matrix was measured. The cell cultures
were analyzed using UV-visible spectroscopy and metabolic rates were determined
using a dissolved oxygen electrode. Through studying the physiological
characterization of the cell cultures and determining a method for the
co-encapsulation of the phototroph and heterotroph within an organic matrix,
the health and metabolic activity of the total consortia was optimized, thus
better replicating a real, living tissue and providing the proof of concept for
creating 3D tissue constructs in the presence of zero external gas exchange.