The development of stem cell biomanufacturing is essential for realizing the potential of stem and progenitor cells for therapies in regenerative medicine. A quantitative framework is proposed for the rational design and optimization of the cultivation of stem cells and their conversion to pancreatic islet cells in bioreactors, which are utilized in the commercial production of biopharmaceuticals. The proposed approach takes into account the inherent heterogeneity of stem cell populations and can be universally applied to progenitor cell differentiation into any clinically relevant phenotype. The theoretical framework is combined with the derivation of functional islet cells as an experimental model system. The expected outcomes will address the unmet need for cellular material for islet replacement therapies with potential benefits to the quality of life of diabetes patients and associated economic burden.
Quantitative models are indispensable for the rational design and prediction of stem cell differentiation processes and their translation to biomanufacturing practices. The inherent heterogeneity of isogenic stem cell ensembles invalidates the averaged population behavior assumed in current models. This application centers on the hypothesis that differentiation can be modeled by population balance equations (PBEs), which are multiscale and take into account temporally distinct intra- and intercellular processes, including stochastic events influencing stem cell physiology. More importantly, stem cell specification along a particular lineage can be described by a distribution (differentiation) function without many of the restrictive assumptions of existing differentiation models. Starting with measurable distributions of cellular traits, the investigators propose to extract differentiation functions via inverse solution of the PBE framework. For this purpose, in the first aim of the proposed studies, human pluripotent stem cell lines will be generated by clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 genome editing. Reporter genes will be inserted downstream of promoters of pluripotency or pancreatic endoderm fate adoption markers. These cell lines will facilitate the identification of subpopulations and the measurement of relevant distributions for the solution of the inverse PBE problem leading to the extraction of differentiation functions. In the second aim, functional expressions describing the state of self-renewing stem cells will be determined from bioreactor cultures. The expansion and directed specification of stem cells will be carried out in a fully automated stirred-suspension bioreactor, permitting both the proper control of operational variables and the investigation of their role on the maintenance of stem cell pluripotency and on specification. Human stem cells will be directed along the pancreatic endoderm lineage in stirred suspension cultures under conditions of varying combinations and concentrations of differentiation stimuli. The planned research activities will provide excellent opportunities for undergraduate and graduate student training. The expected quantitative landscape of pancreatic cell commitment will expedite the development of efficient strategies for the scalable production of islet cells. The universal applicability of the proposed approach will spur similar efforts in the manufacturing of other therapeutically significant cell types such as cardiomyocytes, neurons, hepatocytes, and endothelial cells, with direct impact on the lives of patients afflicted by presently incurable diseases.
