Indiana University-Purdue University Indianapolis (IUPUI) / The young field of gene therapy offers the promises of significant progress towards the treatment of many different types of human diseases. Gene therapy has been proposed as an innovative way to treat Acute Kidney Injury (AKI). Through proteomic analysis, the upregulation of two enzymes, IDH2 and SULT1C2, within the mitochondrial fraction has been identified following ischemic preconditioning, a treatment by which rat kidneys are protected from ischemia. Using the hydrodynamic fluid gene delivery technique, we were able to upregulate the expression of IDH2 and SULT1C2 in the kidney. We found that the delivery of IDH2 plasmid through hydrodynamic fluid delivery to the kidney resulted in increased mitochondrial oxygen respiration compared with injured kidneys without gene delivery. We also found that renal ischemic preconditioning altered the membrane fluidity of mitochondria. In conclusion, our study supports the idea that upregulated expression of IDH2 in mitochondria can protect the kidney against AKI, while the protective function of upregulated SULT1C2 needs to be further studied.

Indiana University-Purdue University Indianapolis (IUPUI) / Acute Kidney Injury (AKI) is a prevalent and significant problem whose primary treatment is supportive care. Ischemic preconditioning is a strategy used to protect organs from ischemic injury via a prior injury. Ischemic preconditioning in the kidneys has been shown to confer protection onto kidneys from subsequent ischemic insults with attenuated serum creatinine values in treated rats. In the preconditioned kidneys, the enzyme IDH2 was discovered to be upregulated in the mitochondria. Hydrodynamic fluid delivery to the kidney was found to be a viable technique for delivering this gene to the kidney, resulting in artificially upregulated expression of IDH2. Via a two-pronged effort to discern the functional significance of ischemic preconditioning and hydrodynamic IDH2 fluid injections, we performed mitochondrial oxygen respiration assays on both preconditioned and injected kidneys. We found that renal ischemic preconditioning resulted in no significant difference between sham and preconditioned, subsequently injured kidneys, which is similar to the results from the serum creatinine studies. Hydrodynamically IDH2-injected, and subsequently injured kidneys respire significantly better than vehicle injected, and subsequently injured kidneys, which shows that hydrodynamic injections of IDH2 protects kidneys against injury, and partially mimics the effects of preconditioning.

Indiana University-Purdue University Indianapolis (IUPUI) / Advancements in human genomics have simultaneously enhanced our basic understanding of the human body and ability to combat debilitating diseases. Historically, research has shown that there have been many hindrances to realizing this medicinal revolution. One hindrance, with particular regard to the kidney, has been our inability to effectively and routinely delivery genes to various loci, without inducing significant injury. However, we have recently developed a method using hydrodynamic fluid delivery that has shown substantial promise in addressing aforesaid issues. We optimized our approach and designed a method that utilizes retrograde renal vein injections to facilitate widespread and persistent plasmid and adenoviral based transgene expression in rat kidneys. Exogenous gene expression extended throughout the cortex and medulla, lasting over 1 month within comparable expression profiles, in various renal cell types without considerably impacting normal organ function. As a proof of its utility we by attempted to prevent ischemic acute kidney injury (AKI), which is a leading cause of morbidity and mortality across among global populations, by altering the mitochondrial proteome. Specifically, our hydrodynamic delivery process facilitated an upregulated expression of mitochondrial enzymes that have been suggested to provide mediation from renal ischemic injury. Remarkably, this protein upregulation significantly enhanced mitochondrial membrane potential activity, comparable to that observed from ischemic preconditioning, and provided protection against moderate ischemia-reperfusion injury, based on serum creatinine and histology analyses. Strikingly, we also determined that hydrodynamic delivery of isotonic fluid alone, given as long as 24 hours after AKI is induced, is similarly capable of blunting the extent of injury. Altogether, these results indicate the development of novel and exciting platform for the future study and management of renal injury.

Indiana University-Purdue University Indianapolis (IUPUI) / The sympathetic nervous system strongly modulates the contractile and electrical function of the heart. The anatomical underpinnings that enable a spatially and temporally coordinated dissemination of sympathetic signals within the cardiac tissue are only incompletely characterized. In this work we took the first step of unraveling the in situ 3D microarchitecture of the cardiac sympathetic nervous system. Using a combination of two-photon excitation fluorescence microscopy and computer-assisted image analyses, we reconstructed the sympathetic network in a portion of the left ventricular epicardium from adult transgenic mice expressing a fluorescent reporter protein in all peripheral sympathetic neurons. The reconstruction revealed several organizational principles of the local sympathetic tree that synergize to enable a coordinated and efficient signal transfer to the target tissue. First, synaptic boutons are aligned with high density along much of axon-cell contacts. Second, axon segments are oriented parallel to the main, i.e., longitudinal, axes of their apposed cardiomyocytes, optimizing the frequency of transmitter release sites per axon/per cardiomyocyte. Third, the local network was partitioned into branched and/or looped sub-trees which extended both radially and tangentially through the image volume. Fourth, sub-trees arrange to not much overlap, giving rise to multiple annexed innervation domains of variable complexity and configuration. The sympathetic network in the epicardial border zone of a chronic myocardial infarction was observed to undergo substantive remodeling, which included almost complete loss of fibers at depths >10 µm from the surface, spatially heterogeneous gain of axons, irregularly shaped synaptic boutons, and formation of axonal plexuses composed of nested loops of variable length. In conclusion, we provide, to the best of our knowledge, the first in situ 3D reconstruction of the local cardiac sympathetic network in normal and injured mammalian myocardium. Mapping the sympathetic network connectivity will aid in elucidating its role in sympathetic signal transmisson and processing.