Characterizing Sex Ratios of American Eels ( Anguilla rostrata ) in Louisiana.

The American eel ( Anguilla rostrata) inhabits Louisiana waterways; however, little is known about their life history, population abundance, or behavior. Eels under 400 mm require histologic evaluation to determine sex. We have processed eel gonad samples from 40 sampling locations across Louisiana, as well as across size categories to aid in establishing a sex determination protocol. One hundred and eighteen (118) eel samples have been histologically analyzed to date. The histologic data compliments morphometric, location, and ageing data collected by the Louisiana Department of Wildlife and Fisheries to build an initial understanding of the biological characteristics of American eels in Louisiana.

Aspects of the alternative host response to methacrylic acid containing biomaterials.

Methacrylic acid (MAA)-based biomaterials promote a vascularized host response without the addition of exogenous factors such as cells or growth factors. We presume that materials containing MAA favor an alternative foreign body response, rather than the conventional fibrotic response. Here, we characterize selected aspects of the response to two different forms of MAA-a coating, which can be used to prevascularize the subcutaneous tissue for subsequent therapeutic cell delivery or an injectable hydrogel, which can be used to vascularize and deliver cells simultaneously. We show that the MAA-coating quickly vascularized the subcutaneous space compared to an uncoated silicone tube, and after 14 days of prevascularization, the tissue surrounding the MAA-coated tube presented fewer immune cells than the uncoated control. We also compared the host response to a MAA-PEG (polyethylene glycol) hydrogel at day 1, with pancreatic islets in immune-compromised SCID/bg mice and immune-competent Balb/c mice. The Balb/c mouse presented a more inflammatory response with increased IFN-γ production as compared to the SCID/bg. Together with previously published data, this work contributes to a further understanding of tissue responses to a biomaterial in different forms as used for cell delivery.

Immunomodulation by subcutaneously injected methacrylic acid-based hydrogels and tolerogenic dendritic cells in a mouse model of autoimmune diabetes.

Type 1 diabetes is an autoimmune disease associated with the destruction of insulin-producing ß cells. Immunotherapies are being developed to mitigate autoimmune diabetes. One promising option is the delivery of tolerogenic dendritic cells (DCs) primed with specific ß-cell-associated autoantigens. These DCs can combat autoreactive cells and promote expansion of ß-cell-specific regulatory immune cells, including Tregs. Tolerogenic DCs are typically injected systemically (or near target lymph nodes) in suspension, precluding control over the microenvironment surrounding tolerogenic DC interactions with the host. In this study we show that degradable, synthetic methacrylic acid (MAA)-based hydrogels are an inherently immunomodulating delivery vehicle that enhances tolerogenic DC therapy in the context of autoimmune diabetes. MAA hydrogels were found to affect the local recruitment and activation state of macrophages, DCs, T cells and other cells. Delivering tolerogenic DCs in the MAA hydrogel improved the local host response (e.g., fewer cytotoxic T cells) and enhanced peripheral Treg expansion. Non obese diabetic (NOD) mice treated with tolerogenic DCs subcutaneously injected in MAA hydrogels showed a delay in onset of autoimmune diabetes compared to control vehicles. Our findings further demonstrate the usefulness of MAA-based hydrogels as platforms for regenerative medicine in the context of type 1 diabetes.

Neutrophil depletion for early allogeneic islet survival in a methacrylic acid (MAA) copolymer-induced, vascularized subcutaneous space.

Islet transplantation is a promising treatment for type I diabetes (T1D). Despite the high loss of islets during transplantation, current islet transplant protocols continue to rely on portal vein infusion and intrahepatic engraftment. Because of the risk of portal vein thrombosis and the loss of islets to instant blood mediated inflammatory reaction (IBMIR), other transplantation sites like the subcutaneous space have been pursued for its large transplant volume, accessibility, and amenability for retrieval. To overcome the minimal vasculature of the subcutaneous space, prevascularization approaches or vascularizing biomaterials have been used to subcutaneously deliver islets into diabetic mice to return them to normoglycemia. Previous vascularization methods have relied on a 4 to 6 week prevascularization timeframe. Here we show that a vascularizing MAA-coated silicone tube can generate sufficient vasculature in 2 to 3 weeks to support a therapeutic dose of islets in mice. In order to fully harness the potential of this prevascularized site, we characterize the unique, subcutaneous immune response to allogeneic islets in the first 7 days following transplantation, a critical stage in successful engraftment. We identify neutrophils as a specific cellular target, a previously overlooked cell in the context of subcutaneous allogeneic islet transplantation. By perioperatively depleting neutrophils, we show that neutrophils are a key, innate immune cell target for successful early engraftment of allogeneic islets in a prevascularized subcutaneous site.

Arctic ice and the ecological rise of the dinosaurs.

Abundant lake ice-rafted debris in Late Triassic and earliest Jurassic strata of the Junggar Basin of northwestern China (paleolatitude ~71°N) indicates that freezing winter temperatures typified the forested Arctic, despite a persistence of extremely high levels of atmospheric Pco2 (partial pressure of CO2). Phylogenetic bracket analysis shows that non-avian dinosaurs were primitively insulated, enabling them to access rich deciduous and evergreen Arctic vegetation, even under freezing winter conditions. Transient but intense volcanic winters associated with massive eruptions and lowered light levels led to the end-Triassic mass extinction (201.6 Ma) on land, decimating all medium- to large-sized nondinosaurian, noninsulated continental reptiles. In contrast, insulated dinosaurs were already well adapted to cold temperatures, and not only survived but also underwent a rapid adaptive radiation and ecological expansion in the Jurassic, taking over regions formerly dominated by large noninsulated reptiles.

Degradable methacrylic acid-based synthetic hydrogel for subcutaneous islet transplantation.

Islet transplantation is a promising regenerative therapy that would reduce the dependence of type 1 diabetic patients on insulin injections. However, islet transplantation is not yet widely available, in part because there is no ideal transplant site. The subcutaneous space has been highlighted as a promising transplant site, but it does not have the vasculature required to support an islet graft. In this study we demonstrate that islets engraft in the subcutaneous space when injected in an inherently vascularizing, degradable methacrylic acid-polyethylene glycol (MAA-PEG) hydrogel; no vascularizing cells or growth factors were required. In streptozotocin-induced diabetic mice, injection of 600 rodent islet equivalents in MAA-PEG hydrogels was sufficient to reverse diabetes for 70 days; a PEG gel without MAA had no benefit. MAA-PEG hydrogel scaffolds degraded over the course of a week and were replaced by a host-derived, vascularized, innervated matrix that supported subcutaneous islets. The survival of islet grafts through the inflammatory events of subcutaneous transplantation, hydrogel degradation, and islet revascularization underscore the benefits of the MAA biomaterial. Our findings establish the MAA-PEG hydrogel as a platform for subcutaneous islet transplantation.

A scalable device-less biomaterial approach for subcutaneous islet transplantation.

The subcutaneous space has been shown to be a suitable site for islet transplantation, however an abundance of islets is required to achieve normoglycemia, often requiring multiple donors. The loss of islets is due to the hypoxic conditions islets experience during revascularization, resulting in apoptosis. Therefore, to reduce the therapeutic dosage required to achieve normoglycemia, pre-vascularization of the subcutaneous space has been pursued. In this study, we highlight a biomaterial-based approach using a methacrylic acid copolymer coating to generate a robust pre-vascularized subcutaneous cavity for islet transplantation. We also devised a simple, but not-trivial, procedure for filling the cavity with an islet suspension in collagen. We show that the pre-vascularized site can support a marginal mass of islets to rapidly return streptozotocin-induced diabetic SCID/bg mice to normoglycemia. Furthermore, immunocompetent Sprague Daley rats remained normoglycemia for up to 70 days until they experienced graft destabilization as they outgrew their implants. This work highlights methacrylic acid-based biomaterials as a suitable pre-vascularization strategy for the subcutaneous space that is scalable and doesn't require exogenous cells or growth factors.

Methacrylic acid copolymer coating of polypropylene mesh chamber improves subcutaneous islet engraftment.

Subcutaneous devices can be used to house therapeutic cells such as pancreatic islets so that the cells can be retrieved. However, a high number of cells may be required to reverse diabetes, since a portion of the graft can be lost after transplantation due to ischemia and therefore the right device design is important. Increasing the vascularity of the subcutaneous space prior to cell transplantation is a strategic goal for cell transplantation, as it promotes islet survival, glucose-sensing and insulin secretion. In this study, a porous cell transplantation device was coated with 40% methacrylic acid-co-isodecyl acrylate (MAA-co-IDA), a biomaterial which promotes a vascular response without additional biologics. Three weeks after device implantation, the vessel density surrounding the device was double that of an uncoated device. The vasculature was mature and connected to the host bloodstream, as demonstrated by perfusion studies and histology. The tissue response to coated devices demonstrated lower levels of inflammation, measured by reduced gene expression of i-NOS and IL1ß, and increased expression of IL4. Syngeneic islets (300 islet equivalents) transplanted into the prevascularized coated device were able to return diabetic animals to normoglycemia for up to 11 weeks and resolve a glucose bolus similarly to non-diabetic mice by 3 weeks post-transplantation. We expect that the vessels and microenvironment resulting from the device coating are permissive to islet survival and thus enabled islets to reverse diabetes.

Endothelialized collagen based pseudo-islets enables tuneable subcutaneous diabetes therapy.

Pancreatic islets are fragile cell clusters and many isolated islets are not suitable for transplantation. Furthermore, following transplantation, islets will experience a state of hypoxia and poor nutrient diffusion before revascularization, which is detrimental to islet survival; this is affected by islet size and health. Here we engineered tuneable size-controlled pseudo-islets created by dispersing de-aggregated islets in an endothelialized collagen scaffold. This supported subcutaneous engraftment, which returned streptozotocin-induced diabetic mice to normoglycemia. Whole-implant imaging after tissue clearing demonstrated pseudo-islets regenerated their vascular architecture and insulin-secreting ß-cells were within 5 µm of a perfusable vessel - a feature unique to this approach. By using an endothelialized collagen scaffold, this work highlights a novel "bottom-up" approach to islet engineering that provides control over the size and composition of the constructs, while enabling the critical ability to revascularize and engraft when transplanted into the clinically useful subcutaneous space.

Mapping Solar System chaos with the Geological Orrery.

The Geological Orrery is a network of geological records of orbitally paced climate designed to address the inherent limitations of solutions for planetary orbits beyond 60 million years ago due to the chaotic nature of Solar System motion. We use results from two scientific coring experiments in Early Mesozoic continental strata: the Newark Basin Coring Project and the Colorado Plateau Coring Project. We precisely and accurately resolve the secular fundamental frequencies of precession of perihelion of the inner planets and Jupiter for the Late Triassic and Early Jurassic epochs (223-199 million years ago) using the lacustrine record of orbital pacing tuned only to one frequency (1/405,000 years) as a geological interferometer. Excepting Jupiter's, these frequencies differ significantly from present values as determined using three independent techniques yielding practically the same results. Estimates for the precession of perihelion of the inner planets are robust, reflecting a zircon U-Pb-based age model and internal checks based on the overdetermined origins of the geologically measured frequencies. Furthermore, although not indicative of a correct solution, one numerical solution closely matches the Geological Orrery, with a very low probability of being due to chance. To determine the secular fundamental frequencies of the precession of the nodes of the planets and the important secular resonances with the precession of perihelion, a contemporaneous high-latitude geological archive recording obliquity pacing of climate is needed. These results form a proof of concept of the Geological Orrery and lay out an empirical framework to map the chaotic evolution of the Solar System.