Biomedical subjects

Kendrick C Boardman

Publications and source records attributed to Kendrick C Boardman.

6 recordsLinked to original sources

PubMed2006

Characterization of lymphangiogenesis in a model of adult skin regeneration.

To date, adult lymphangiogenesis is not well understood. In this study we describe the evolution of lymphatic capillaries in regenerating skin and correlate lymphatic migration and organization with the expression of matrix metalloproteinases (MMPs), immune cells, the growth factors VEGF-A and VEGF-C, and the heparan sulfate proteogylcan perlecan, a key component of basement membrane. We show that while lymphatic endothelial cells (LECs) migrate and organize unidirectionally, in the direction of interstitial fluid flow, they do not sprout into the region but rather migrate as single cells that later join together into vessels. Furthermore, in a modified "shunted flow" version of the model, infiltrated LECs fail to organize into functional vessels, indicating that interstitial fluid flow is necessary for lymphatic organization. Perlecan expression on new lymphatic vessels was only observed after vessel organization was complete and also appeared first in the distal region, consistent with the directionality of lymphatic migration and organization. VEGF-C expression peaked at the initiation of lymphangiogenesis but was reduced to lower levels throughout organization and maturation. In mice lacking MMP-9, lymphatics regenerated normally, suggesting that MMP-9 is not required for lymphangiogenesis, at least in mouse skin. This study thus characterizes the process of adult lymphangiogenesis and differentiates it from sprouting blood angiogenesis, verifies its dependence on interstitial fluid flow for vessel organization, and correlates its temporal evolution with those of relevant environmental factors.

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PubMed2006

Autologous morphogen gradients by subtle interstitial flow and matrix interactions.

Cell response to extracellular cues is often driven by gradients of morphogenetic and chemotactic proteins, and therefore descriptions of how such gradients arise are critical to understanding and manipulating these processes. Many of these proteins are secreted in matrix-binding form to be subsequently released proteolytically, and here we explore how this feature, along with small dynamic forces that are present in all tissues, can affect pericellular protein gradients. We demonstrate that 1), pericellular gradients of cell-secreted proteins can be greatly amplified when secreted by the cell in matrix-binding form as compared to a nonmatrix-interacting form; and 2), subtle flows can drive significant asymmetry in pericellular protein concentrations and create transcellular gradients that increase in the direction of flow. This study thus demonstrates how convection and matrix-binding, both physiological characteristics, combine to allow cells to create their own autologous chemotactic gradients that may drive, for example, tumor cells and immune cells into draining lymphatic capillaries.

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PubMed2005

Complete and specific inhibition of adult lymphatic regeneration by a novel VEGFR-3 neutralizing antibody.

BACKGROUND: New lymphatic growth may contribute to tumor metastasis. Activation of vascular endothelial growth factor receptor 3 (VEGFR-3) by its ligands VEGF-C and -D is necessary for embryonic and tumor lymphangiogenesis. However, the exact role of VEGFR-3 signaling in adult lymphangiogenesis and in lymphatic vessel survival and regeneration is unclear. METHODS: A novel rat monoclonal antibody to murine VEGFR-3, mF4-31C1, which potently antagonizes the binding of VEGF-C to VEGFR-3, was developed. We tested the effects of systemic mF4-31C1 administration in a mouse tail skin model of lymphatic regeneration, either with or without local overexpression of VEGF-C, and we observed lymphatic and blood vessel regeneration over time using microlymphangiography and immunostaining. RESULTS: Normal mice regenerated complete and functional lymphatic vessels within 60 days of surgery. In athymic mice implanted with VEGF-C-overexpressing human breast carcinoma cells, lymphatic regeneration took place over 25 days and resulted in hyperplastic vessels. Under either condition, no lymphatic regeneration occurred in mice receiving mF4-31C1 during the regeneration period. Blood angiogenesis and preexisting lymphatic vessels were unaffected, both in morphology and in function. CONCLUSIONS: Blocking VEGFR-3 completely and specifically prevented both physiologically normal and tumor VEGF-C-enhanced lymphangiogenesis in the adult mouse but had no effect on either blood angiogenesis or the survival or function of existing lymphatic vessels. Thus, targeting VEGFR-3 with specific inhibitors may block new lymphatic growth exclusively.

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PubMed2004

Actin re-distribution in response to hydrogen peroxide in airway epithelial cells.

Reactive oxygen species (ROS) disrupt the barrier function of airway epithelial cells through a mechanism that appears to involve remodeling of the actin cytoskeleton. Similarly, keratinocyte growth factor (KGF) has been shown to protect against ROS-induced loss of barrier function through a mechanism that may also involve the actin cytoskeleton. To further determine the role of the actin cytoskeleton in ROS-induced barrier injury, we quantified the relative amount of total actin associated with the cytoskeleton following exposure to hydrogen peroxide (H(2)O(2)) and pretreatment with KGF. We also determined the role of the actin-myosin contractile mechanism in the process by quantifying the relative amount of myosin heavy chain (MHC) associated with the cytoskeleton. While the transepithelial resistance (TER) of a monolayer of airway epithelial cells (Calu-3) decreased after 2 h of continuous exposure to 0.5 mM H(2)O(2), actin and MHC, both dissociated from the cytoskeleton within 15 min of H(2)O(2) exposure. The TER of the monolayers remained depressed although both actin and myosin returned to the cytoskeleton by 4 h after the initiation of H(2)O(2) exposure. Filamentous actin (f-actin) staining suggested that the re-associating actin took the form of short fibers associated with cortical actin rather than long stress fibers. Furthermore, pretreatment with KGF prevented the loss of actin and MHC from the actin cytoskeleton but did not prevent the decrease in TER. These studies suggest that actin disassembly from the cytoskeleton is important in the loss of barrier function, but that it is not the overall amount of actin that is associated with the cytoskeleton that is important, rather it is the contribution this actin makes to the architectural cohesiveness of the cell that contributes to the barrier function.

Actins↗

PubMed2003

Interstitial flow as a guide for lymphangiogenesis.

The lymphatic system is important in tissue fluid balance regulation, immune cell trafficking, edema, and cancer metastasis, yet very little is known about the sequence of events that initiate and coordinate lymphangiogenesis. Here, we characterize the process of lymphatic regeneration by uniquely correlating interstitial fluid flow and lymphatic endothelial cell migration with lymphatic function. A new model of skin regeneration using a collagen implant in a mouse tail has been developed, and it shows that (1) interstitial fluid channels form before lymphatic endothelial cell organization and (2) lymphatic cell migration, vascular endothelial growth factor-C expression, and lymphatic capillary network organization are initiated primarily in the direction of lymph flow. These data suggest that interstitial fluid channeling precedes and may even direct lymphangiogenesis (in contrast to blood angiogenesis, in which fluid flow proceeds only after the vessel develops); thus, a novel and robust model is introduced for correlating molecular events with functionality in lymphangiogenesis.

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PubMed2002

The role of interstitial stress in lymphatic function and lymphangiogenesis.

The management and control of tissue fluid balance depends on the highly regulated orchestration of various interstitial factors. In particular, lymphatic function, lymphatic biology, and development (lymphangiogenesis), and the extracellular matrix all contribute to interstitial fluid balance. In light of the dynamic interdependence of these factors, our lab has been working towards establishing a mechanical-molecular picture of the process of lymphangiogenesis-that is, bridging the physiological context of lymphangiogenesis with its molecular regulation by studying the coordination of mechanical forces, ECM development, lymphatic biology, and lymphatic capillary organization and development. Our working hypothesis is that the physiological driving force for lymphangiogenesis is the need for organized interstitial fluid flow. This paper will outline the rationale and background for such an approach and highlight some of the recently published findings of our lab and others that support this concept.

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