Interferon-gamma/Hypoxia Primed Mesenchymal Stem Cells for an Improved Immunosuppressive Cell Therapy

Mesenchymal stem cells (MSCs) are promising candidates for treating diverse inflammatory disorders due to their capacity to be immunosuppressive. This phenotype is not present at baseline but develops in response to instructive cues. To date, clinical trials use cells grown in basic culture conditions, anticipating the cells will acquire a useful phenotype in response to in vivo cues. This strategy has failed to produce any FDA approved therapies, based on inconsistent efficacy. This thesis explores whether priming MSCs prior to administration can lead to a more uniformly therapeutic phenotype, and it details the design of an optimal in vitro priming regimen. Because interferon gamma (IFN-γ) is known to induce an anti-inflammatory state in MSCs, hypoxia can confer survival benefits, and both cues coexist in known situations of immune tolerance, we hypothesized dual IFN-γ/hypoxia priming would yield a superior immunosuppressive MSC therapy. We show that priming MSCs with hypoxia or IFN-γ alone improves their ability to inhibit T-cells in vitro, but combining these cues results in additive improvements. We next characterize the proteomic and metabolomic changes MSCs undergo when exposed to single or dual IFN-γ/hypoxia priming. While IFN-γ induces MSCs to suppress inflammation and fibrosis, hypoxia leads to cell adaptations to low oxygen, including upregulation of proteins involved in anaerobic metabolism, autophagy, angiogenesis, and cell migration. Dual priming results in additive effects, with many instances of synergy. Finally, we show initial evidence that dual primed MSCs are better able to inhibit disease progression in a mouse model of acute graft-vs-host disease (GvHD)

Functional vascularized lung grafts for lung bioengineering

End-stage lung disease is the third leading cause of death worldwide, accounting for 400,000 deaths per year in the United States alone. To reduce the morbidity and mortality associated with lung disease, new therapeutic strategies aimed at promoting lung repair and increasing the number of donor lungs available for transplantation are being explored. Because of the extreme complexity of this organ, previous attempts at bioengineering functional lungs from fully decellularized or synthetic scaffolds lacking functional vasculature have been largely unsuccessful. An intact vascular network is critical not only for maintaining the blood-gas barrier and allowing for proper graft function but also for supporting the regenerative cells. We therefore developed an airway-specific approach to removing the pulmonary epithelium, while maintaining the viability and function of the vascular endothelium, using a rat model. The resulting vascularized lung grafts supported the attachment and growth of human adult pulmonary cells and stem cell–derived lung-specified epithelial cells. We propose that de-epithelialization of the lung with preservation of intact vasculature could facilitate cell therapy of pulmonary epithelium and enable bioengineering of functional lungs for transplantation