Research

Our group engages in areas of bioengineering related to cell engineering and bioprocessing for improving human health. Toward this goal, experimental approaches in tandem with computational methods are employed.

Stem cell engineering

Stem cells can serve as inexhaustible source of functional cells for addressing life-altering pathologies including diabetes and cardiac diseases. Realization of this potential depends on the production of therapeutically useful stem cell derivatives in clinically relevant quantities. Our work in this area focuses on addressing facets of stem cell bioprocessing including the effects of the bioreactor environment and metabolism on the physiology of stem cells during propagation or directed specification to cells such as pancreatic endocrine cells. 

(A) Stirred suspension culture of human pluripotent stem cells in an automated bioreactor. (B) Directed differentiation of MEL1 INSGFP/w human stem cells to insulin-producing (GFP+) cells. Bars: 200 µm.

This work is coupled with multiscale modeling and digital twins capturing the heterogeneous nature of stem cell ensembles. Elucidation of the role of the exhibited heterogeneity on cell and tissue fate determination and function is key to developing efficient strategies for engineering stem cell products.


Optogenetic control of cellular function

We employ optogenetics relying on the use of light-activated proteins to control specific cell functions such as the contractility of cardiomyocytes and the secretion of hormones by pancreatic endocrine cells. This requires the careful design and embedding of synthetic circuits in the cellular machinery for precise control of the desired function without detrimental side effects.

To enhance the amount of insulin secreted by pancreatic β-cells in a drug-free manner, our group has engineered rodent and human β-cells expressing a bacterial photoactivatable adenylyl cyclase (PAC). Activation of PAC with light augments the glucose-stimulated release of insulin compared to cells without PAC. These findings open prospects of engineering systems which allow drug-free control of blood glucose, for example, in diabetic patients. Pancreatic β-cells expressing PACs can be integrated in a bioartificial pancreas device along with an appropriate light source for stimulation and a glucose sensor, enabling future diabetes therapies.

(A) Schematic of blue-light PAC embedded in the molecular circuit of β-cells for glucose-stimulated secretion of insulin. (B) Insulin release by pancreatic islet cells expressing PAC under different glucose concentrations. #,*p<0.05. (C) Glucose tolerance test results for diabetic mice receiving PAC-engineered β-cells with and without stimulation with light. ***p<0.05.

Reg protein biology

Regenerating islet-derived (Reg) proteins were discovered in the pancreatic secretions of patients with chronic calcifying pancreatitis. However, the presence of Reg proteins has been confirmed both in pancreatic and extra-pancreatic tissues particularly under diverse pathological conditions such as diabetes and cancer. Reg proteins have been postulated to promote proliferation and differentiation while preventing apoptosis, but there is very little known about their exact role(s) almost 50 years after their discovery. Our research focuses on gaining a deeper understanding of the physiological functions of Reg proteins and underlying mechanisms in normal tissue homeostasis and disease.

(A) Mouse pancreatic tissue showing the expression of Reg1 protein. Insulin expression demarcates islets. Bars: 50 µm. (B) The production of Reg1 protein is curtailed in pancreatic acinar cells with over expression of microRNA-7 (miR7 OE). *p<0.05.

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