TR&D-3: Bio-instructive Bioreactors

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Project Summary/Abstract: Bioreactor systems are critical for cohesive engineered tissues to mature from cells and scaffolds. Many bioreactors are compatible with the periodic, non-invasive measurement of basic environmental parameters, like dissolved O2, pH and temperature and other, tissue-specific in-process and final product quality attributes. However, the ability to (1) non-invasively measure cell and tissue maturation against a series of redetermined, tissue-specific biological and mechanical quality attributes and (2) to provide biological and mechanical stimulation to structural tissues, does not exist. Furthermore, closed/sealed systems to mitigate contamination require non-invasive measurement technologies, especially for measuring quality attributes of autologous/personalized tissues of which only a single unit may exist. We will develop a closed, bio-instructive bioreactor platform, amenable to the culture of various structural tissues, and incorporating sensing and actuation for feedback control of process parameters using the following specific aims. Aim 1: Development and integration of sensors to monitor physio-chemical cell status/maturity, and tissue mechanical properties. We will first investigate integration of optical sensors into bioreactor vessels with a focus on optimized signal acquisition and analysis. We will develop (and then also integrate) ultrasonic assessment of tissue construct mechanical properties such as one-dimensional modulus, and tissue inhomogeneity and surface defects. Together with the off-line analysis of key metabolites and nutrients (e.g., amino acids, growth factors), these inputs will provide detailed information on the phenotype and health of the engineered tissue. Aim 2: Modular bioreactor development, including actuators for mechanical stimulation, sequential growth factor regulation, and injection systems. Inputs from embedded, in-line, and off-line sensors will be processed and exported to two types of programmable actuators:1) fluid dispensers for chemical stimuli, and 2) mechanical stimuli delivered via flexion, sheer, and/or compression. The bioreactor platforms will be developed with emphasis on integration with Tissue Foundry modules, and on downstream compatibility with its automation and data management backbone. The internal configuration of the bioreactor will be specific to the tissues in development by our CPs and will be designed for optimal fluid flow paths for cell seeding, media exchanges and nutrient addition via PLC-controlled actuators and valves. For tissues requiring mechanical stimulation, the modular reactor will have integrated deformable polymeric walls, through which the tissue can be mechanically manipulated in a sterile manner. Sterile ports and fiberoptic ports will be embedded into the bioreactor walls for the delivery of biological effectors and to enable O2 uptake or other analyte measurements. Feedback control algorithms will be developed for sensing and actuation for mechanical quality control of a single tissue type.