Curated Optogenetic Publication Database

Abstract: Bioelectronic medicine is emerging as a powerful approach for restoring lost endogenous functions and addressing life-altering maladies such as cardiac disorders. Systems that incorporate both modulation of cellular function and recording capabilities can enhance the utility of these approaches and their customization to the needs of each patient. Here is report an integrated optogenetic and bioelectronic platform for stable and long-term stimulation and monitoring of cardiomyocyte function in vitro. Optical inputs are achieved through the expression of a photoactivatable adenylyl cyclase, that when irradiated with blue light causes a dose-dependent and time-limited increase in the secondary messenger cyclic adenosine monophosphate with subsequent rise in autonomous cardiomyocyte beating rate. Bioelectronic readouts are obtained through a multi-electrode array that measures real-time electrophysiological responses at 32 spatially-distinct locations. Irradiation at 27 µW mm-2 results in a 14% elevation of the beating rate within 20-25 min, which remains stable for at least 2 h. The beating rate can be cycled through "on" and "off" light states, and its magnitude is a monotonic function of irradiation intensity. The integrated platform can be extended to stretchable and flexible substrates, and can open new avenues in bioelectronic medicine, including closed-loop systems for cardiac regulation and intervention, for example, in the context of arrythmias.

Abstract: Enhancement of glucose-stimulated insulin secretion (GSIS) in exogenously delivered pancreatic β-cells is desirable, for example, to overcome the insulin resistance manifested in type 2 diabetes or to reduce the number of β-cells for supporting homeostasis of blood sugar in type 1 diabetes. Optogenetically engineered cells can potentiate their function with exposure to light. Given that cyclic adenosine monophosphate (cAMP) mediates GSIS, we surmised that optoamplification of GSIS is feasible in human β-cells carrying a photoactivatable adenylyl cyclase (PAC). To this end, human EndoC-βH3 cells were engineered to express a blue-light-activated PAC, and a workflow was established combining the scalable manufacturing of pseudoislets (PIs) with efficient adenoviral transduction, resulting in over 80% of cells carrying PAC. Changes in intracellular cAMP and GSIS were determined with the photoactivation of PAC in vitro as well as after encapsulation and implantation in mice with streptozotocin-induced diabetes. cAMP rapidly rose in β-cells expressing PAC with illumination and quickly declined upon its termination. Light-induced amplification in cAMP was concomitant with a greater than 2-fold GSIS vs β-cells without PAC in elevated glucose. The enhanced GSIS retained its biphasic pattern, and the rate of oxygen consumption remained unchanged. Diabetic mice receiving the engineered β-cell PIs exhibited improved glucose tolerance upon illumination compared to those kept in the dark or not receiving cells. The findings support the use of optogenetics for molecular customization of the β-cells toward better treatments for diabetes without the adverse effects of pharmacological approaches.

Abstract: Optogenetic modalities as well as optochemical and photopharmacological strategies, collectively termed optical methods, have revolutionized the control of cellular functions via light with great spatiotemporal precision. In comparison to the major advances in the photomodulation of signaling activities noted in neuroscience, similar applications to endocrine cells of the pancreas, particularly insulin-producing β-cells, have been limited. The availability of tools allowing light-mediated changes in the trafficking of ions such as K+ and Ca2+ and signaling intermediates such as cyclic adenosine monophosphate (cAMP), renders β-cells and their glucose-stimulated insulin secretion (GSIS) amenable to optoengineering for drug-free control of blood sugar.

Abstract: Pharmacological augmentation of glucose-stimulated insulin secretion (GSIS), for example, to overcome insulin resistance in type 2 diabetes is linked to suboptimal regulation of blood sugar. Cultured β-cells and islets expressing a photoactivatable adenylyl cyclase (PAC) are amenable to GSIS potentiation with light. However, whether PAC-mediated enhancement of GSIS can improve the diabetic state remains unknown. To this end, β-cells were engineered with stable PAC expression that led to over 2-fold greater GSIS upon exposure to blue light while there were no changes in the absence of glucose. Moreover, the rate of oxygen consumption was unaltered despite the photoinduced elevation of GSIS. Transplantation of these cells into streptozotocin-treated mice resulted in improved glucose tolerance, lower hyperglycemia, and higher plasma insulin when subjected to illumination. Embedding optogenetic networks in β-cells for physiologically relevant control of GSIS will enable novel solutions potentially overcoming the shortcomings of current treatments for diabetes.

Abstract: Pancreatic β-cell insulin production is orchestrated by a complex circuitry involving intracellular elements including cyclic AMP (cAMP). Tackling aberrations in glucose-stimulated insulin release such as in diabetes with pharmacological agents, which boost the secretory capacity of β-cells, is linked to adverse side effects. We hypothesized that a photoactivatable adenylyl cyclase (PAC) can be employed to modulate cAMP in β-cells with light thereby enhancing insulin secretion. To that end, the PAC gene from Beggiatoa (bPAC) was delivered to β-cells. A cAMP increase was noted within 5 minutes of photostimulation and a significant drop at 12 minutes post-illumination. The concomitant augmented insulin secretion was comparable to that from β-cells treated with secretagogues. Greater insulin release was also observed over repeated cycles of photoinduction without adverse effects on viability and proliferation. Furthermore, the expression and activation of bPAC increased cAMP and insulin secretion in murine islets and in β-cell pseudoislets, which displayed a more pronounced light-triggered hormone secretion compared to that of β-cell monolayers. Calcium channel blocking curtailed the enhanced insulin response due to bPAC activity. This optogenetic system with modulation of cAMP and insulin release can be employed for the study of β-cell function and for enabling new therapeutic modalities for diabetes.