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We report three millimeter line observations of young stellar object (YSO) cluster IRAS 08563−4225 in the Vela C molecular cloud, detecting outflow aligned with an unidentified 2MASS infrared emission maximum. Emission features such as velocity dispersion ridges converging on intermediate mass Class I protostar IRS 31 14 indicate cluster wind driven turbulence, a scenario supported within an evolutionary framework derived from a range of star-forming regions. Prestellar–pre-main-sequence evolution is regulated by internal core turbulence and tracked on a Δ(σ2)–log ma diagram in four stages: disc formation, wind generation, outflow collimation, and birthline emergence, where ma = $\dot{M}_{\text{acc}}\, t_{\mathrm{out}}$ is a mass parameter given by $\dot{M}_{\text{acc}}$, the accretion rate and tout, the outflow dynamical time, and Δ(σ2) = log ($\frac{\sigma ^2_{\mathrm{outer}}}{\sigma ^2_{\mathrm{inner}}}$) with σinner, the inner and σouter, the outer core velocity dispersion. A turnover in Δ(σ2) indicates the generation of supersonic turbulence in star-forming regions with inner core collapse; in sets of low, intermediate, and high mass protostellar regions, a negative turbulent index at = $\frac{\text{d}{\Delta }\sigma ^2}{\text{dlog}m_a}$ corresponds to increasing age. Inner core collapse driven turbulence may apply at kiloparsec scales with turbulence amplification in a series of interacting YSO cluster cores in different evolutionary stages.

The entire Earth was bombarded c.4100-3800 Ma, establishing initial conditions for all later regional geology. Deep impact-fractures have been regenerated upward from the brittle-ductile boundary by the action of convection, outgassing, circulating fluids, the twice-daily earth-tide, and earthquakes throughout all subsequent time. In consequence, many such fractures have never entirely healed or been eliminated. The two-dimensional map-outlines and circular curvature of numerous three-dimensional “craterform” scars can be readily seen, once the observer has been alerted to the possibility of their existence. Many other Hadean/EoArchean impact-scars are covered over, as is the case at present, at any given time. These impact features have been regenerated “cold” from below and are fundamentally different from astroblemes, as presently defined, whose rocks were directly subjected to the high temperatures and pressures that accompany hypervelocity extra-terrestrial impacts. Melt rock filled the largest impact sites and produced cratons, with overflow producing platforms. In later times, craton rims buckled during collisions, producing orogens. Crater rims originally entered the Earth at near-vertical angles but after sufficient net erosion following Snowball Earth episodes, deeply exposed rim-zones entered the Earth at lower angles, thereby facilitating deep subduction. Renewed activation of earliest Precambrian fractures from below is a recurrent geological phenomenon. The largest scar, approximately 5350 kilometers in diameter, encompasses Asia and has Novaya Zemlya as part of an outer rim. Our vision has greatly improved since 1788 when James Hutton could find “no vestige of a beginning”.

Age-related macular degeneration (AMD) is a retinal disease that affects 196 million people and causes nearly 9% of blindness worldwide. While several pharmacological approaches slow the effects of AMD, in our opinion, cell-based strategies offer the most likely path to a cure. We describe the design and initial characterization of a kerateine (obtained by reductive extraction from keratin proteins) aerogel-electrospun polycaprolactone fiber scaffold system. The scaffolds mimic key features of the choroid and the Bruch’s membrane, which is the basement membrane to which the cells of the retinal pigment epithelium (RPE) attach. The scaffolds had elastic moduli of 2–7.2 MPa, a similar range as native choroid and Bruch’s membrane. ARPE-19 cells attached to the polycaprolactone fibers, remained viable for one week, and proliferated to form a monolayer reminiscent of that needed for retinal repair. These constructs could serve as a model system for testing cell and/or drug treatment strategies or directing ex vivo retinal tissue formation in the treatment of AMD.

Bombardment of the Earth at an early date established initial conditions that have affected all later regional geology. No part of the Earth's crust escaped. Activity at the brittle-ductile boundary has caused large-diameter scars to be sporadically regenerated upward throughout the four-billion years of our planet's history. Although these three-dimensional 'craterform' scars have evolved in many different manners, and many are covered over at any given time, many retain observable two-dimensional map-outlines with circular curvature. These inherited scar-features have been regenerated 'cold' from below and are fundamentally different from 'astroblemes', as presently defined, whose constituent rocks had been directly subjected to the high temperatures and pressures that accompany extra-terrestrial impacts. The varied present-day manifestations of these scars need to be described and categorized as has been done for faults, folds, rocks, and minerals by earlier workers in the earth sciences.

Background: A pro-inflammatory diet has been posited to induce chronic inflammation within the central nervous system (CNS), and multiple sclerosis (MS) is an inflammatory disease of the CNS. Objective: We examined whether Dietary Inflammatory Index (DII®)) scores are associated with measures of MS progression and inflammatory activity. Methods: A cohort with a first clinical diagnosis of CNS demyelination was followed annually (10 years, n = 223). At baseline, 5- and 10-year reviews, DII and energy-adjusted DII (E-DIITM) scores were calculated (food frequency questionnaire) and assessed as predictors of relapses, annualised change in disability (Expanded Disability Status Scale) and two magnetic resonance imaging measures; fluid-attenuated inversion recovery (FLAIR) lesion volume and black hole lesion volume. Results: A more pro-inflammatory diet was associated with a higher relapse risk (highest vs. lowest E-DII quartile: hazard ratio = 2.24, 95% confidence interval (CI) = −1.16, 4.33, p = 0.02). When we limited analyses to those assessed on the same manufacturer of scanner and those with a first demyelinating event at study entry (to reduce error and disease heterogeneity), an association between E-DII score and FLAIR lesion volume was evident (β = 0.38, 95% CI = 0.04, 0.72, p = 0.03). Conclusion: There is a longitudinal association between a higher DII and a worsening in relapse rate and periventricular FLAIR lesion volume in people with MS.

Energy poses challenges to environmental studies because of climate change and other effects, and field trips are indispensable aids to learning. They enable students to see situations first-hand, and many are joyous and fun, such as field trips to forests, wetlands, wildlife reserves, or communities exhibiting positive contributions to safeguarding the natural world. Field trips to the built environment, especially those illustrating sites with raging controversies or past catastrophes are equally important in helping students turn theory into understanding of real situations. Chernobyl, one of the two worst nuclear power plant disasters, provided the venue for a field trip examining the strengths and weaknesses of nuclear power. Students had 3 weeks of preparatory classwork before departing for Kyiv, Ukraine. They spent 2 weeks there, with 1 day touring the Exclusion Zone surrounding the Chernobyl plant. Background work included basic concepts and units for measuring radiation and their biological and medical effects, types of nuclear power plants, disaster planning and response, Ukrainian history, and details of the Chernobyl accident and its effects. Participants heard from a wide variety of speakers, who presented details of the accident, its lingering consequences, efforts of the Ukrainian government and various NGOs to deal with the consequences, and Ukrainian plans for new nuclear power plants. Participants also heard both strong pro-nuclear and anti-nuclear proponents. At the end, students prepared a paper on the lessons about nuclear power from Chernobyl. Evaluations of the experience indicated the trip’s objectives were achieved. For some, the expedition proved life-altering.

Alien species are a major cause of species extinctions globally and the effects of introductions can become substantial, especially once aliens become entrenched and impossible to eradicate. Some entrenched aliens may assume niches of extinct native species that are functionally similar, but the capacity of an alien to perform specialised ecological processes is unknown. Here we examine the potential for the alien black rat (Rattus rattus) to effectively pollinate native Banksia ericifolia in heath at North Head, Sydney where endemic mammalian pollinators such as brown antechinus (Antechinus stuartii) and eastern pygmy-possums (Cercartetus nanus) had been locally extinct prior to recent reintroductions. Using artificial inflorescences, we compared the use of inflorescences, visit frequency and duration of alien black rats to reintroduced natives according to the stem diameter of the inflorescence. Black rats were the most frequent visitor and they spent similar or more time at artificial inflorescences as natives, but they also spent more time visiting inflorescences with thicker stem diameters. In contrast, the native mammals visited artificial inflorescences regardless of the stem thickness. We suggest that, as black rats are heavier than the native mammals, this could limit their capacity as substitute pollinators of B. ericifolia. This finding shows the importance of understanding the extent of the benefits of aliens before relying on them as functional replacements for extinct natives.

Providing suitable 24-hour patient care is a difficult topic for many veterinary practices (VP) and involves many ethical dilemmas to ensure that the patient's, staff's and clients' needs are met. Following rules and regulations to prevent litigation, providing care for good patient outcomes and upholding client expectations at an affordable price, alongside the provision for staff wellbeing makes this a difficult task. Evidence-based research, technology and effective communication skills may help to solve these dilemmas.

Age-related macular degeneration (AMD) is a retinal disease that affects 196 million people and causes nearly 9% of blindness worldwide. While several pharmacological approaches slow the effects of AMD, in our opinion, cell-based strategies offer the most likely path to a cure. We describe the design and initial characterization of a kerateine (obtained by reductive extraction from keratin proteins) aerogel-electrospun polycaprolactone fiber scaffold system. The scaffolds mimic key features of the choroid and the Bruch's membrane, which is the basement membrane to which the cells of the retinal pigment epithelium (RPE) attach. The scaffolds had elastic moduli of 2-7.2 MPa, a similar range as native choroid and Bruch's membrane. ARPE-19 cells attached to the polycaprolactone fibers, remained viable for one week, and proliferated to form a monolayer reminiscent of that needed for retinal repair. These constructs could serve as a model system for testing cell and/or drug treatment strategies or directing ex vivo retinal tissue formation in the treatment of AMD.

Libyan Desert Glass (LDG), rediscovered in modern times in 1932, is an ultrahigh-temperature glass composed of nearly pure SiO2. LDG is found as surface float in Egypt’s Libyan (Western) Desert, it...

Large impact craters that pierced the early Earth’s thin hot crust formed scars that never fully healed. These scars provided initial geological conditions for our planet and its deep plumbing system. On oceanic crust they provide arcuate downdipping sites, which, eroded, eventually allowed subduction to occur. On continental crust, they determine many geological features, which are generally difficult to see because they are covered by later formations through which repropagated fractures have not attained the surface. Shock criteria for the identification of astroblemes are absent because they were immediately swamped by the disproportionate amount of melt produced by very large impacts.

Many graduate programs in environmental studies attempt to foster specialized knowledge and technical skills alongside interdisciplinary collaboration and integration. We discuss strategies for addressing these distinct—sometimes competing—goals in Evergreen State College’s Graduate Program on the Environment. Key strategies include (1) designing an academic program that balances specialization and integration; (2) approaching course planning with a “backward design model” that focuses on teaching outcomes rather than “covering” disciplinary content; (3) designing group assignments that require collaborative and multidisciplinary research and networking among students; (4) approaching thesis projects using place-based issues or research problems/questions developed in conjunction with local or regional organizations and a clear identification of relevant communities of practice to inform the scholarly work and analysis. Finally, we address the challenge of creating equitable social dynamics in teaching teams and offer reflections based on our 30-year tradition of collaborative team-teaching at the graduate level.

Safe clinical hormone replacement (HR) will likely become increasingly important in the growing populations of aged women and cancer patients undergoing treatments that ablate the ovaries. Cell-based HRT (cHRT) is an alternative approach that may allow certain physiological outcomes to be achieved with lower circulating hormone levels than pharmacological means due to participation of cells in the hypothalamus-pituitary-ovary feedback control loop. Here we describe the in vivo performance of 3D bioengineered ovarian constructs that recapitulate native cell–cell interactions between ovarian granulosa and theca cells as an approach to cHRT. The constructs are fabricated using either Ca++ or Sr++ to crosslink alginate. Following implantation in ovariectomized (ovx) rats, the Sr++-cross-linked constructs achieve stable secretion of hormones during 90 days of study. Further, we show these constructs with isogeneic cells to be effective in ameliorating adverse effects of hormone deficiency, including bone health, uterine health, and body composition in this rat model., Cell-based hormone replacement therapy (cHRT) may be an alternative therapy to pharmacological (p)HRT. Here, the authors show that implanted 3D bioengineered ovarian constructs of granulosa and theca cells in ovariectomized rats recapitulate native cell interactions and improve efficacy compared to similar doses of pHRT.

An incomplete nuclear reactor project shut down after more than nine years of work and nine billion dollars invested. A war of words between Korean President Kim Jong Un and U.S. President Donald Trump and the threat of nuclear war. These two seemingly disconnected events are linked by a common denominator—the ongoing fascination with the power of the atom. Two recently published books can help those not familiar with the history of commercial or military nuclear power in the USA make better sense of these current events as they explore the highs and lows of the nuclear industry. Atomic Geography: A Personal History of the Hanford Nuclear Reservation by Melvin R. Adams captures personal insights into the waning years at Hanford, when plutonium production for the US weapons stockpile was giving way to environmental clean-up. James W. Feldman’s Nuclear Reactions: Documenting American Encounters with Nuclear Energy provides excerpts of 70 years of published documents to describe the ongoing hope in what nuclear energy might provide for society and intense fear of a nuclear melt down or all-out nuclear war. Together, the two books provide an interesting picture of nuclear industry in the USA.

Certain hard and normally opaque minerals, both rare and common, occasionally crystallize as transparent or partly transparent ‘gem’ crystals. Such stones, designated ‘crystalline coloured ...

Direct dating of corundum and the establishment of age constraints for corundum crystal growth are restricted due to the absence of a geochronometer. Syngenetic mineral inclusions may help define minimum ages for corundum growth. Here, we present results of in situ LA-ICP-MS U–Pb dating applied to rutile inclusions in corundum from localities along the Mozambique belt. U–Pb dating of rutile inclusions gave ages of 533 ± 11 Ma (2 σ) for the Gitonga pit (John Saul ruby mine) and 526 ± 13 Ma for the Aqua Ruby mine, both in the Mangari area of Kenya, and an age of 499 ± 12 Ma for ruby from the Morogoro area, Tanzania. These ages are interpreted as cooling ages that set a minimum age for corundum growth following metamorphism along the East-African Antarctic Orogen, and might be used for petrogenetic tracing of corundum in placer deposits.

Background: Drug-coated balloons (DCBs), which deliver anti-proliferative drugs with the aid of excipients, have emerged as a new endovascular therapy for the treatment of peripheral arterial disease. In this study, we evaluated the use of keratose (KOS) as a novel DCB-coating excipient to deliver and retain paclitaxel. Methods: A custom coating method was developed to deposit KOS and paclitaxel on uncoated angioplasty balloons. The retention of the KOS-paclitaxel coating, in comparison to a commercially available DCB, was evaluated using a novel vascular-motion simulating ex vivo flow model at 1 h and 3 days. Additionally, the locoregional biological response of the KOS-paclitaxel coating was evaluated in a rabbit ilio-femoral injury model at 14 days. Results: The KOS coating exhibited greater retention of the paclitaxel at 3 days under pulsatile conditions with vascular motion as compared to the commercially available DCB (14.89 &plusmn, 4.12 ng/mg vs. 0.60 &plusmn, 0.26 ng/mg, p = 0.018). Histological analysis of the KOS&ndash, paclitaxel-treated arteries demonstrated a significant reduction in neointimal thickness as compared to the uncoated balloons, KOS-only balloon and paclitaxel-only balloon. Conclusions: The ability to enhance drug delivery and retention in targeted arterial segments can ultimately improve clinical peripheral endovascular outcomes.

Additional file 1: Figure S1. ZO-1 immunofluorescence was performed on control (n = 4) and ALS CP (n = 5) and staining was imaged under 20x using confocal microscopy. DAPI denotes nuclei and DIC (differential interference contrast) images were taken to show tissue morphology. Scale bar: 50um. Red arrowheads point to areas of loss of ZO-1 staining in between CP epithelial cells. Figure S2. A) Immunohistochemistry for Claudin 5 was performed on control (n = 3) and ALS CP (n = 5). Pictures were taken at 40X magnification. Scale bar: 20 μm. Black Arrows point to staining in endothelial cells and red arrowheads point to staining within the lumen of blood vessels. B) Western blot analysis was performed on 9 controls and 18 SALS CP lysates and membranes were probed for Claudin 3 and 5, as well as Occludin. GAPDH was used as a loading control. Figure S3. A) Quantification of immunofluorescence signal intensity for CD13 and PDGFRbeta on n = 3 control and n = 5 ALS CP samples was performed using Imaris. Image stacks were taken at 63x magnification and ten different Z-stack fields per sample were captured and quantified. Tissues boundaries were delineated and signal intensity was normalized to section volume. The asterisk denotes significance with a p-value of 0.0095. Values for PDGFRbeta were not found to be significant. B) CD13/ANPEP immunohistochemistry in ALS (n = 5) and control (n = 4) CP. Black arrows point to CD13 stain around blood vessels on controls and red arrowheads denote vascular areas of CD13 loss in ALS. Figure S4 A) CD3 staining in ALS-CP tissues. Scale bar: 20 μm. B) MERTK immunohistochemistry in ALS and Control CP. Pictures were taken at low magnification to show extent of MERTK expression. Scale bar 100 μm C) p-TDP43 (S409/410) staining in CP from ALS and Control postmortem tissues. Only two ALS cases showed any inclusions, and these were located in the choroid stroma. Scale bar: 20 μm. Figure S5 Heatmap showing Z-scores across all samples for all gene targets that had reliable MSD signal. Samples are presented in their respective groups (control vs ALS), ranked by cumulative sum of all analytes measured. Figure S6 All cytokines and chemokines analyzed by MSD immunoassays in n = 22 controls and n = 44 ALS-CP lysates. None of the shown analytes showed significant differences between the two groups through a logistic regression analysis that accounts for patient age (under 65 vs above 65), as well as the plate on which the sample was run to avoid batch effect bias. Both IFN-γ and TNF-α had low signal to background ratio. Supplemental Table 1. ToppGene Analysis showing the top 30 enriched Biological Processes. Supplemental Table 2. MSD immunoassay analysis of CP lysates from ALS and non-neurological disease controls. Supplemental Table 3. Demographics for post-mortem tissue samples. Supplemental Table 4. CP samples used for RNA-seq. Supplemental Table 5. List of antibodies used in analysis of CP samples.

To evaluate the biological, immunological, and biomechanical properties of a scaffold derived by architectural modification of a fresh-frozen porcine patella tendon using a decellularization protocol that combines physical, chemical, and enzymatic modalities.Porcine patellar tendons were processed using a decellularization and oxidation protocol that combines physical, chemical, and enzymatic modalities. Scaffolds (n = 88) were compared with native tendons (n = 70) using histologic, structural (scanning electron microscopy, porosimetry, and tensile testing), biochemical (mass spectrometry, peracetic acid reduction, DNA quantification, alpha-galactosidase [α-gal] content), as well as in vitro immunologic (cytocompatibility, cytokine induction) and in vivo immunologic nonhuman primate analyses.A decrease in cellularity based on histology and a significant decrease in DNA content were observed in the scaffolds compared with the native tendon (P.001). Porosity and pore size were increased significantly (P.001). Scaffolds were cytocompatible in vitro. There was no difference between native tendons and scaffolds when comparing ultimate tensile load, stiffness, and elastic modulus. The α-gal xenoantigen level was significantly lower in the decellularized scaffold group compared with fresh-frozen, nondecellularized tissue (P.001). The in vivo immunological response to implanted scaffolds measured by tumor necrosis factor-α and interleukin-6 levels was significantly (P.001) reduced compared with untreated controls in vitro. These results were confirmed by an attenuated response to scaffolds in vivo after implantation in a nonhuman primate model.Porcine tendon was processed via a method of decellularization and oxidation to produce a scaffold that possessed significantly less inflammatory potential than a native tendon, was biocompatible in vitro, of increased porosity, and with significantly reduced amounts of α-gal epitope while retaining tensile properties.Porcine-derived scaffolds may provide a readily available source of material for musculoskeletal reconstruction and repair while eliminating concerns regarding disease transmission and the morbidity of autologous harvest.

The term “ ontogeny ,” which is commonly used in biology, was introduced into the Earth sciences in 1961 to include the genesis and evolution of single crystals and crystal aggregates. The term encompasses nucleation , growth , alteration , and destruction . We present results of studies concerning the ontogeny of natural corundum (rubies and sapphires), and the chemical and morphological evolution of corundum crystals from deposits in Africa (Kenya, Tanzania, Madagascar) and Southeast Asia (Vietnam). Trace-element compositions indicative for different corundum habits were determined by rim-to-rim LA-ICP-MS and electron microprobe analyses. Raman spectroscopy was applied for Cr 3+ photoluminescence mapping. Results traced the development of corundum crystals and the evolution of their chemistry and morphology, and helped to clarify the geological processes within particular deposits. These variations of corundum morphology are directly correlated with Cr and Fe contents and varying P-T conditions that prevailed during crystal growth. Dipyramidal habits combined with white color in corundum from two deposits in the Mangari area in Kenya have Cr concentrations of ~200–700 μg/g in crystals that grew under high P-T conditions. Prismatic habit of bright red ruby crystals was linked to Cr concentrations of ≥1500 μg/g in samples from Luc Yen (Vietnam) and Mangari (Kenya), formed under lower P-T . Concentrations of Cr between 700–1500 μg/g are associated with pink color and combinations of different habits (dipyramidal, prismatic, or dipyramidal-prismatic) in these samples. Contents of Fe ~700 μg/g and Cr ~1200 μg/g in sapphire crystals from the Morogoro area of Tanzania caused pink color that correlated with dipyramidal habit and elongation along the c axis. Rhombohedral habit and blue-violet color were observed at Cr ~600 μg/g and Fe ≥2000 μg/g in sapphires from Andranondambo in Madagascar, formed during the final stage of contact metamorphism.

The thiol–Michael adduct is used as a thermoresponsive dynamic cross-linker in polymeric materials. Recently, the thiol–Michael reaction between thiols and conjugated alkenes has been used as a ligation reaction for polymer synthesis and functionalization. Here, the thiol–Michael reaction is demonstrated to be thermally responsive and dynamic. Small molecule model experiments demonstrate the potential for the thiol–Michael adducts to be used in dynamic covalent chemistry. Thiol–acrylate adducts are incorporated into a cross-linker to form a soft polymeric material. These thiol–Michael cross-linked materials display healing after being cut and malleability characteristics at 90 °C. Additionally, the data suggest that there is limited creep and stress relaxation at room temperature with complete recovery of creep once the strain is removed. These thiol–Michael cross-linked polymers show dynamic properties upon thermal stimulus, with long-term stability against mechanical deformation in the absence of this s...

Purpose: Drug coated balloons (DCB) are continually improving due to advances in coating techniques and more effective excipients. Paclitaxel, the current drug choice of DCB, is a microtubule-stabilizing chemotherapeutic agent that inhibits smooth muscle cell proliferation. Excipients work to promote coating stability and facilitate paclitaxel transfer and retention at the target lesion, although current excipients lack sustained, long-term paclitaxel retention. Keratose, a naturally derived protein, has exhibited unique properties allowing for tuned release of various therapeutic agents. However, little is known regarding its ability to support delivery of anti-proliferative agents such as paclitaxel. The goal of this project was to thus demonstrate the feasibility of keratose as a DCB-coating excipient to promote the release and delivery of paclitaxel. Methods: Keratose was combined with paclitaxel in vitro and the release kinetics of paclitaxel and keratose were evaluated through high performance liquid chromatograph-mass spectroscopy (HPLC-MS) and spectrophotometry, respectively. A custom coating method was developed to deposit keratose and paclitaxel on commercially available angioplasty balloons via an air spraying method. Coatings were then visualized under scanning electron microscopy and drug load quantified by HPLC-MS. Acute arterial transfer of paclitaxel at 1 h was assessed using a novel ex vivo model and further evaluated in vivo in a porcine ilio-femoral injury model. Results: Keratose demonstrated tunable release of paclitaxel as a function of keratose concentration in vitro. DCB coated via air spraying yielded consistent drug loading of 4.0 ± 0.70 μg/mm2. Under scanning electron microscopy, the keratose-paclitaxel DCB showed uniform coverage with a consistent, textured appearance. The acute drug transfer of the keratose-paclitaxel DCB was 43.60 ± 14.8 ng/mg at 1 h ex vivo. These measurements were further confirmed in vivo as the acute 1 h arterial paclitaxel levels were 56.60 ± 66.4 ng/mg. Conclusion: The keratose-paclitaxel coated DCB exhibited paclitaxel uptake and achieved acute therapeutic arterial tissue levels, confirming the feasibility of keratose as a novel excipient for DCB.

Bone fracture followed by delayed or non-union typically requires bone graft intervention. Autologous bone grafts remain the clinical "gold standard". Recently, synthetic bone grafts such as Medtronic's Infuse Bone Graft have opened the possibility to pharmacological and tissue engineering strategies to bone repair following fracture. This clinically-available strategy uses an absorbable collagen sponge as a carrier material for recombinant human bone morphogenetic protein 2 (rhBMP-2) and a similar strategy has been employed by Stryker with BMP-7, also known as osteogenic protein-1 (OP-1). A key advantage to this approach is its "off-the-shelf" nature, but there are clear drawbacks to these products such as edema, inflammation, and ectopic bone growth. While there are clinical challenges associated with a lack of controlled release of rhBMP-2 and OP-1, these are among the first clinical examples to wed understanding of biological principles with biochemical production of proteins and pharmacological principles to promote tissue regeneration (known as regenerative pharmacology). After considering the clinical challenges with such synthetic bone grafts, this review considers the various biomaterial carriers under investigation to promote bone regeneration. This is followed by a survey of the literature where various pharmacological approaches and molecular targets are considered as future strategies to promote more rapid and mature bone regeneration. From the review, it should be clear that pharmacological understanding is a key aspect to developing these strategies.

Antagonists and inhibitory molecules responsible for maintaining tissue homeostasis can present a significant barrier to healing when tissue engineering/regenerative medicine strategies are employed. One example of this situation is the up-regulation of antagonists such as noggin in response to increasing concentrations of bone morphogenetic protein-2 (BMP-2) present from endogenous bone repair processes or delivered exogenously from biomaterials (synthetic bone grafts). While recombinant human (rh)BMP-2 delivered from synthetic bone grafts has been shown to be an effective alternative to autografts and allografts, the supraphysiological doses of rhBMP-2 have led to clinically-adverse side effects. The high rhBMP-2 dosage may be required, in part, to overcome the presence of antagonists such as noggin. Small interfering RNA (siRNA) is an appealing approach to overcome this problem because it can knock-down antagonists or inhibitory molecules in a temporary manner. Here, we conducted fundamental studies on the delivery of siRNA from material surfaces as a means to knock-down antagonists like noggin. Non-viral cationic lipid (Lipofectamine)–siRNA complexes were delivered from a fibrin hydrogel surface to MC3T3-E1 preosteoblasts that were treated with a supraphysiological dose of rhBMP-2 to achieve noggin mRNA expression levels higher than cells naive to rhBMP-2. Confocal microscopy and flow cytometry showed intracellular uptake of siRNA in over 98% of MC3T3-E1 cells after 48 h. Doses of 0.5 and 1 μg noggin siRNA were able to significantly reduce noggin mRNA to levels equivalent to those in MC3T3-E1 cells not exposed to rhBMP-2 with no effects on cell viability. Statement of significance Small interfering RNA (siRNA) has been considered for treatment of diseases ranging from Alzheimer’s to cancer. However, the ability to use siRNA in conjunction with biomaterials to direct tissue regeneration processes has received relatively little attention. Using the bone morphogenetic protein 2 antagonist, noggin, as a model, this research describes an approach to knock-down molecules that are inhibitory to desired regenerative pathways at the mRNA level via siRNA delivery from a hydrogel surface. Interactions between the material (fibrin) surface and polycation–siRNA complexes, release of the siRNA from the material surface, high levels of cellular uptake/internalization of siRNA, and significant knockdown of the targeting (noggin) mRNA are demonstrated. Broader future applications include those to nerve regeneration, cardiovascular tissue engineering, directing (stem) cell behavior, and mitigating inflammatory responses to materials.

Polymeric biomaterials that provide a matrix for cell attachment and proliferation while achieving delivery of therapeutic agents are an important component of tissue engineering and regenerative medicine strategies. Keratins are a class of proteins that have received attention for numerous tissue engineering applications because, like other natural polymers, they promote favorable cell interactions and have non-toxic degradation products. Keratins can be extracted from various sources including human hair, and they are characterized by a high percentage of cysteine residues. Thiol groups on reductively extracted keratin (kerateine) form disulfide bonds, providing a more stable cross-linked hydrogel network than oxidatively extracted keratin (keratose) that cannot form disulfide crosslinks. We hypothesized that an iodoacetamide alkylation (or "capping") of cysteine thiol groups on the kerateine form of keratin could be used as a simple method to modulate the levels of disulfide crosslinking in keratin hydrogels, providing tunable rates of gel erosion and therapeutic agent release. After alkylation, the alkylated kerateines still formed hydrogels and the alkylation led to changes in the mechanical and visco-elastic properties of the materials consistent with loss of disulfide crosslinking. The alkylated kerateines did not lead to toxicity in MC3T3-E1 pre-osteoblasts. These cells adhered to keratin at levels comparable to fibronectin and greater than collagen. Alkylated kerateine gels eroded more rapidly than non-alkylated kerateine and this control over erosion led to tunable rates of delivery of rhBMP-2, rhIGF-1, and ciprofloxacin. These results demonstrate that alkylation of kerateine cysteine residues provides a cell-compatible approach to tune rates of hydrogel erosion and therapeutic agent release within the context of a naturally-derived polymeric system.

Objective: Cutaneous wound infection can lead to impaired healing, multiple surgical procedures, and increased hospitalization time. We tested the effectiveness of keratin-based hydrogels (termed “keratose”) loaded with ciprofloxacin to inhibit infection and support healing when topically administered to porcine excision wounds infected with Pseudomonas aeruginosa. Approach: Using a porcine excisional wound model, 10 mm full-thickness wounds were inoculated with 106 colony-forming units of P. aeruginosa and treated on days 1 and 3 postinoculation with ciprofloxacin-loaded keratose hydrogels. Bacteria enumeration and wound healing were assessed on days 3, 7, and 11 postinjury. Results: Ciprofloxacin-loaded keratose hydrogels reduced the amount of P. aeruginosa in the wound bed by 99.9% compared with untreated wounds on days 3, 7, and 11 postinjury. Ciprofloxacin-loaded keratose hydrogels displayed decreased wound contraction and reepithelialization at day 7 postinjury. By day 11, wounds treated with ciprof...