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.

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.

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.

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.

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.

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.