• Stem cell engineering
  • Optogenetic control of cellular function
  • Regenerating (Reg) protein biology

Stem cell engineering

Stem cells can be differentiated to therapeutically valuable cell types including heart muscle cells and pancreatic insulin-producing cells. Realization of this potential of stem cells in regenerative medicine hinges on their robust cultivation in clinically relevant quantities beyond typical dish cultures in the laboratory. Our work is geared toward the development of bioprocesses for the advanced manufacturing of stem cell-based products. Central to our efforts is the utilization of stirred-suspension bioreactors, suitable materials and media for the expansion of self-renewing stem cells and their directed specification to relevant cell fates. Stirred-suspension bioreactor modalities include the expansion and specification of stem cells as aggregates, on microcarriers and after encapsulation.

Such systems allow to explore the effects of the bioreactor environment on the physiology of stem cells and their differentiated progeny. Emphasis has been placed on the culture environment and cause-effect relationships of metabolites such as lactate impacting stem cell physiology, phenotype, and differentiation propensity. This work is coupled with multiscale modeling capturing the heterogeneous nature of stem cell ensembles. Elucidating the role of the exhibited heterogeneity on cell and tissue fate determination and function will be key to the development of strategies for the efficient engineering of stem cell products.

Optogenetic control of cellular function

Optogenetics rely on the use of specialized molecules which are de/activated by light. These light-driven changes influence particular cellular functions such as the contractility of cardiomyocytes and the depolarization of retinal gangliocytes. Despite their advantages over drug-based approaches, optogenetic approaches require the intelligent design of synthetic circuits to be embedded in the cellular machinery for precise control of the desired function.

In an effort to control the amount of insulin secreted by pancreatic β-cells, our group recently engineered β-cells expressing a bacterial photoactivatable adenylyl cyclase (PAC). Activation with light of PAC augmented the release of insulin compared to cells not expressing PAC (control) in the presence of various concentrations of glucose. 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.

Reg protein biology

Regenerating islet-derived (Reg) proteins were discovered in the pancreatic juice of patients suffering from chronic calcifying pancreatitis but their presence 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 cellular proliferation and differentiation, and prevent apoptosis, but there is very little known about their exact function(s) almost 40 years after their identification. Our laboratory is interested in establishing the physiological functions of these proteins and gaining a deeper understanding of the underlying mechanisms utilized by Reg proteins in normal tissue homeostasis and disease.