Inhibition of Vascular Endothelial Growth Factor Receptor Decreases Regenerative Angiogenesis in Axolotls.

Angiogenesis is crucial for tissue growth and repair in mammals, and is chiefly regulated by vascular endothelial growth factor (VEGF) signaling. We evaluated the effect of chemical inhibition of VEGF receptor signaling in animals with superior regenerative ability, axolotl salamanders, to determine the impact on vascularization and regenerative outgrowth. Following tail amputation, treated animals (100 nM PTK787) and controls were examined microscopically and measured over the month-long period of regeneration.

Comparison of tissue processing methods for microvascular visualization in axolotls.

The vascular system, the pipeline for oxygen and nutrient delivery to tissues, is essential for vertebrate development, growth, injury repair, and regeneration. With their capacity to regenerate entire appendages throughout their lifespan, axolotls are an unparalleled model for vertebrate regeneration, but they lack many of the molecular tools that facilitate vascular imaging in other animal models. The determination of vascular metrics requires high quality image data for the discrimination of vessels from background tissue.

Methylene Blue Assay for Estimation of Regenerative Re-Epithelialization In Vivo.

The rapidity with which epithelial cells cover a wound surface helps determine whether scarring or scar-less healing results. As methylene blue is a vital dye that is absorbed by damaged tissue but not undamaged epidermis, it can be used to assess wound closure. We sought to develop a quantitative methylene blue exclusion assay to estimate the timeframe for re-epithelialization in regenerating appendages in zebrafish and axolotls, two classic model systems of regeneration.

Deep pulmonary lymphatics in immature lungs.

Recently, we found that the translocation of inhaled nanoparticles from the air space to secondary organs is age dependent and substantially greater in neonates than in adults (J Respir Crit Care Med 177: A48, 2008). One reason for this difference might be age-dependent differences in alveolar barrier integrity. Because the neonate lung is undergoing morphogenetic and fluid balance changes, we hypothesize that the alveolar barrier of developing lungs is more easily compromised and susceptible to foreign material influx than that of adult lungs.

Integrin binding angiopoietin-1 monomers reduce cardiac hypertrophy.

Angiopoietins were thought to be endothelial cell-specific via the tie2 receptor. We showed that angiopoietin-1 (ang1) also interacts with integrins on cardiac myocytes (CMs) to increase survival. Because ang1 monomers bind and activate integrins (not tie2), we determined their function in vivo.

Distribution and quantity of contractile tissue in postnatal development of rat alveolar interstitium.

Alpha-smooth muscle actin (alpha-SMA) -expressing cells are important participants in lung remodeling, during both normal postnatal ontogeny and after injury. Developmental dysregulation of these contractile cells contributes to bronchopulmonary dysplasia in newborns, and aberrant recapitulation in adults of the normal ontogeny of these cells has been speculated to underlie disease and repair in mature lungs. The significance of airway smooth muscle has been widely investigated, but contractile elements within the pulmonary parenchyma, although also of structural and functional consequence in developing and mature lungs, are relatively unstudied and little quantitative information exists.

Pericyte coverage of abnormal blood vessels in myelofibrotic bone marrows.

Background And Objectives: Myelofibrotic bone marrow displays abnormal angiogenesis but the pathogenic mechanisms of this are poorly understood. Since pericyte abnormalities are described on solid tumor vessels we studied whether vessel morphology and pericyte coverage in bone marrow samples from patients with myelofibrosis differed from that in samples from controls.

Design And Methods: We assessed the microvascular density (MVD), vessel morphology and pericyte coverage in bone marrows from 19 myelofibrosis patients and nine controls.

Extraction and reconstitution of calponin and consequent contractile ability in permeabilized smooth muscle fibers.

We demonstrate reduction and restoration of contractile ability in response to protein extraction and reconstitution in Triton X-100/glycerol-permeabilized smooth muscle fibers. Through significant reduction in the content of caldesmon (CaD), calponin (CaP), and the 20-kDa regulatory light chain (RLC) of myosin, but not other contractile proteins in "chemically skinned" fibers, we substantially reduced the contractile ability of these fibers, as measured by their ability to generate isometric force and to hydrolyze ATP by actomyosin Mg2+ ATPase. When the protein-depleted fibers were then reconstituted (either with a mixture of purified protein standards of CaD, CaP, and myosin RLC or with a protein extract from the demembranized muscle fibers containing CaD, CaP, and myosin RLC plus several low-molecular-mass proteins), all proteins used for reincorporation returned nearly to control levels, as did isometric force generation and rate of ATP hydrolysis.