Disrupting the vicious cycle created by NOX activation in sickle erythrocytes exposed to hypoxia/reoxygenation prevents adhesion and vasoocclusion.

In sickle cell disease (SCD), recurrent painful vasoocclusive crisis are likely caused by repeated episodes of hypoxia and reoxygenation. The sickle erythrocyte (SSRBC) adhesion plays an active role in vasoocclusion. However, the effect of prolonged reoxygenation after hypoxic stress on the molecular mechanisms in SSRBCs involved in onset of episodic vasoocclusion remain unclear. Exposure of human SSRBCs to hypoxia followed by 2 h reoxygenation, increased reactive oxygen species (ROS) production. Using specific pharmacological inhibitors, we show that excess ROS production in both reticulocytes and mature SSRBCs is regulated by NADPH oxidases (NOXs), the mitogen-activated protein kinase (ERK1/2), and G-protein coupled-receptor kinase 2 (GRK2). Consequently, SSRBC ROS create an intracellular positive feedback loop with ERK1/2 and GRK2 to mediate SSRBC adhesion to endothelium in vitro, and vasoocclusion in a mouse model of vasoocclusion in vivo. Importantly, reducing ROS levels in SSRBCs with redox-active manganese (Mn) porphyrins, commonly known as mimics of superoxide dismutase (SOD), disrupted the cycle created by ROS by affecting NOX and GRK2 activities and ERK1/2 phosphorylation, thus abrogating RBC-endothelial interactions. Inhibition adhesion assays show that LW (ICAM-4, CD242) blood group glycoprotein and CD44 are the RBC adhesion molecules mediating endothelial binding. Conversely, hypoxia/reoxygenation of normal RBCs failed to activate this feedback loop, and adhesion. These findings provide novel insights into the pathophysiological significance of the deleterious cycle created by NOX-dependent ROS, GRK2 and ERK1/2 within SSRBCs activated by hypoxia/reoxygenation, and involved in SSRBC adhesion and vasoocclusion. Thus, this loop in SSRBCs, which can be disrupted by Mn porphyrins, likely drives the profound SCD vasculopathy, and may point to new therapeutic targets to prevent chronic vasoocclusive events.

Molecular Additives Significantly Enhance Glycopolymer-Mediated Transfection of Large Plasmids and Functional CRISPR-Cas9 Transcription Activation Ex Vivo in Primary Human Fibroblasts and Induced Pluripotent Stem Cells.

Fast, efficient, and inexpensive methods for delivering functional nucleic acids to primary human cell types are needed to advance regenerative medicine and cell therapies. Plasmid-based gene editing (such as with CRISPR-Cas9) can require the delivery of plasmids that are large (∼9.5-13 kbp) in comparison to common reporter plasmids (∼5-8 kbp). To develop more efficient plasmid delivery vehicles, we investigated the effect of plasmid size on the transfection of primary human dermal fibroblasts (HDFs) and induced pluripotent stem cells (iPSCs) using a heparin-treated trehalose-containing polycation (Tr4-heparin). Transfections with 4.7 kbp to 10 kbp plasmids exhibited high rates of polyplex internalization with both plasmid sizes. However, transfection with the large plasmid was nearly eliminated in HDFs and significantly reduced in iPSCs. Molecular additives were used to probe intracellular barriers to transfection. Chloroquine treatments were used to destabilize endosomes, and dexamethasone and thymidine were used to destabilize the nuclear envelope. Destabilizing the nuclear envelope resulted in significantly increased large-plasmid-transfection, indicating that nuclear localization may be more difficult for large plasmids. To demonstrate the potential clinical utility of this formulation, HDFs and iPSCs were treated with to dexamethasone-Tr4-heparin polyplexes encoding dCas9-VP64, synthetic transcription activator, targeted to collagen type VII. These transfections enhanced collagen expression in HDFs and iPSCs by 5- and 20-fold, respectively, compared to an untransfected control and were the more effective than the Lipofectamine 2000 control. Functional plasmid transfection efficiency can be significantly improved by nuclear destabilization, which could lead to improved development of nonviral vehicles for ex vivo CRISPR-Cas9 gene editing.

Development and Preliminary Evaluation of a Murine Model of Chronic Radiation-Induced Proctitis.

PURPOSE: Radiotherapy (RT) is commonly used to treat most pelvic malignancies. While treatment is often effective, curative radiation doses to the rectum can result in chronic radiation-induced proctitis, which is characterized by diarrhea, tenesmus, and/or rectal bleeding, recently termed pelvic radiation disease. An animal model of chronic radiation-induced proctitis would be useful to test both preventative and therapeutic strategies to limit this morbidity but has been elusive because of the high rodent mortality associated with acute bowel RT injury. The objective of this research was to develop a novel mouse model of chronic radiation-induced proctitis using advanced technology. METHODS AND MATERIALS: Using an X-RAD 225-Cx (Precision X-Ray) small animal irradiator, multiple plan configurations were evaluated for planning treatment volume and organ-at-risk avoidance to deliver a 15 Gy 3D conformal treatment plan. The final plan was verified by high resolution 3D dosimetry (PRESAGE/optical-CT), and delivered using a single arc. Mice were monitored for mortality for 250 days, followed by histopathological correlates including mucicarmine, Masson's trichrome, and fecal pellet length. RESULTS: Six beam arrangements were considered: single and parallel-opposed fields with whole-pelvis coverage, and collimated fields in parallel-opposed, 3-field, 4-field, and arc geometries. A collimated arc plan offered superior planning treatment volume coverage and organ-at-risk avoidance compared to whole-pelvis irradiation. Treatment verification with PRESAGE 3D dosimetry (Heuris Inc) showed >99% of voxels passing gamma analysis with 2%/2 mm criteria. Our treatment resulted in no acute mortality and 40% mortality at 250 days. Histopathological analysis showed increased mucous production and fibrosis of the irradiated colon, but no change in fecal pellet length. CONCLUSIONS: Our model was able to target successfully lower colon and rectum with lower mortality than other published models. This permitted measurement of late effects that recapitulate some features of rectal damage in humans.