Thoracoscopic surgery for pulmonary nodules in patients with previous malignant tumor

We evaluated the clinico-pathological characteristics of thirty-four cases with previous malignant tumor who was operated under thoracoscopy for pulmonary nodules. In twenty-three cases (67.6%), including 20 cases suspected metastatic pulmonary tumor before operation, thoracoscopic surgery was performed without doing the preoperative examinations for the definite diagnosis. The mean diameter of resected tumors was 13.5 mm and the definite diagnosis was determined in all cases by the intraoperative pathological diagnosis. There were 26(76.5%) cases of malignancy, including 20 cases(58.8%) of metastatic pulmonary tumor and 6 cases (17.7%) of primary lung cancer. Accuracy rate of predictive diagnosis before operation was 67.6%. From the analysis of difference between pre- and post-operative diagnoses, inflammatory nodules or tuberculoma in the solitary nodule and intrapulmonary lymph nodes or silicotic nodules in the multiple nodules should have been considered with more carefully attention. Univariate and multivariate analysis showed that patients with metastatic tumor previously was only a predictive factor for metastatic tumor. Age, gender, CT findings, the number of nodules, disease free interval and tumor markers were unreliable factors in this study. In conclusion, there were a lot of cases with previous malignant tumor in which thoracoscopic surgery could become a first choice of modalities for the diagnosis of pulmonary nodules. Early thoracoscopic procedure will be recommended for such patients to perform the immediate treatment.     

A new method of reconstruction for chest wall resection

Sixteen patients who involved in chest wall disease underwent major chest wall resection between April 1995 and January 1999. The underlying diseases were 6 recurrence of breast cancers, 4 direct invasion by primary lung cancer, 2 metastatic chest wall tumor, one direct invasion by metastatic lung tumor, one direct invasion by metastatic mediastinal tumor, one radio-induced-necrosis of the chest wall, and one chest wall infection. In 9 patients, the thoracic cage reconstruction was performed using double sheets of absorbable mesh (Dexon mesh), cross string sutures and autologous ribs grafts. None of the patients had major respiratory failure and chest wall unstability. No late complications including infections, pains, recurrence and others related to reconstruction materials have been observed.     

MFG-E8 Regulates Angiogenesis in Cutaneous Wound Healing

Our research group recently demonstrated that pericytes are major sources of the secreted glycoprotein and integrin ligand lactadherin (MFG-E8) in B16 melanoma tumors, and that MFG-E8 promotes angiogenesis via enhanced PDGF–PDGFRβ signaling mediated by integrin–growth factor receptor crosstalk. However, sources of MFG-E8 and its possible roles in skin physiology are not well characterized. The objective of this study was to characterize the involvement of MFG-E8 in skin wound healing. In the dermis of normal murine and human skin, accumulations of MFG-E8 were found around CD31⁺ blood vessels, and MFG-E8 colocalized with PDGFRβ⁺, αSMA⁺, and NG2⁺ pericytes. MFG-E8 protein and mRNA levels were elevated in the dermis during full-thickness wound healing in mice. MFG-E8 was diffusely present in granulation tissue and was localized around blood vessels. Wound healing was delayed in MFG-E8 knockout mice, compared with the wild type, and myofibroblast and vessel numbers in wound areas were significantly reduced in knockout mice. Inhibition of MFG-E8 production with siRNA attenuated the formation of capillary-like structures in vitro. Expression of MFG-E8 in fibrous human granulation tissue with scant blood vessels was less than that in granulation tissue with many blood vessels. These findings suggest that MFG-E8 promotes cutaneous wound healing by enhancing angiogenesis.Wound healing is a dynamic process involving angiogenesis, production of soluble mediators and extracellular matrix, and migration of various types of cells, including keratinocytes, fibroblasts, macrophages, and leukocytes. Dysregulation of this interactive process may result in delayed wound healing, as is seen in chronic skin ulcers or scarring. Wound healing has three temporally overlapping phases: inflammation, tissue formation, and remodeling.^1,2 The inflammation phase occurs immediately after wounding. It is characterized by hypoxia with fibrin clot formation, as well as recruitment of neutrophils and platelets. Tissue formation occurs 2 to 10 days later and is characterized by epithelialization, formation of granulation tissue and new blood vessels, and accumulation of macrophages and fibroblasts. Activated macrophages release growth factors, such as vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF), and initiate angiogenesis. PDGF receptor β (PDGFRβ) signaling is essential for angiogenesis and for recruitment, proliferation, and normal function of fibroblasts and pericytes during the tissue-formation phase.³ Blockade of VEGF receptor signaling and PDGFRβ signaling inhibits angiogenesis and results in delayed wound healing,^3,4 indicating that angiogenesis is critical for normal wound healing.The secreted glycoprotein lactadherin was initially identified as a component of milk fat globules and is here referred to as milk fat globule-EGF factor 8 (MFG-E8); other names in the literature include secreted protein containing epidermal growth factor (EGF) repeats and discoidin/F5/8 domains 1, or SED1. MFG-E8 comprises two N-terminal EGF-like domains, and two C-terminal discoidin-like domains (C1 and C2) share homology with blood coagulation factors V and VIII.^5–9 One EGF-like domain (E2) contains an RGD consensus integrin-binding motif, and MFG-E8 binds to integrin αvβ3/5.^7–11 The C-terminal domains of MFG-E8 can bind to negatively charged and oxidized phospholipids,^12,13 facilitating opsonization of apoptotic cells for uptake by phagocytes.^10,14 This process has been reported to contribute to autoimmunity, mastitis, sepsis, atherosclerosis, and Alzheimer disease.^15–19 Interactions of MFG-E8 with CD51 (integrin αv) have also been implicated in regulation of angiogenesis and mammary gland branching,^11,20 and interactions mediated via the C1 domain are thought to be important for sperm–egg binding and collagen turnover.^21,22Our research group has previously demonstrated that MFG-E8 enhances angiogenesis in tumors and in oxygen-induced retinopathy in mice.²³ We determined that pericytes and/or pericyte precursors are important sources of MFG-E8 in vivo, that MFG-E8 enhances angiogenesis via actions on pericytes as well as endothelial cells (ECs), and that MFG-E8 can be effectively targeted with therapeutic benefit.²³ In murine melanomas and in retinas of mice with oxygen-induced retinopathy, MFG-E8 colocalized with pericytes rather than with ECs, and pericytes purified from tumors contained large amounts of MFG-E8 mRNA. Tumor- and retinopathy-associated angiogenesis was diminished in MFG-E8 knockout (KO) mice, and pericyte coverage of neovessels was also reduced. Inhibition of MFG-E8 production by pericyte/pericyte precursor-like 10T1/2 cells using siRNAs, or inhibition of MFG-E8 action with some anti–MFG-E8 antibodies, attenuated PDGF-BB–induced 10T1/2 cell migration, but did not affect proliferation or differentiation.²³ We have also determined that MFG-E8 produced by 10T1/2 cells associated with integrin αv and PDGFRβ on cell surfaces after PDGF-BB treatment, altered the distribution of PDGFRβ within cells and delayed PDGF-BB–stimulated degradation of PDGFRβ, thereby enhancing PDGFRβ signaling mediated by integrin–growth factor receptor crosstalk.²⁴In a study of MFG-E8, epithelial tissues, and wound healing, Bu et al²⁵ found that MFG-E8 promotes the migration of intestinal epithelial cells via a PKCε-dependent mechanism engaged by binding of MFG-E8 to phosphatidylserine. Their findings indicate that MFG-E8 is involved in the maintenance of intestinal epithelial homeostasis and the promotion of mucosal healing. The possible role of MFG-E8 in cutaneous wound healing has not been studied previously. In the present study, we analyzed skin wound healing using MFG-E8 wild-type (WT) and KO mice. We demonstrate that MFG-E8 production was increased and that MFG-E8 accumulated in granulation tissue during wound healing, and that wound healing in MFG-E8 KO mice was delayed. We relate delayed wound healing to diminished angiogenesis and myofibroblast infiltration in wounds in MFG-E8 KO mice.     

Neurotrophin production in brain pericytes during hypoxia: a role of pericytes for neuroprotection

Neurotrophins are crucial regulators of neuronal survival and death. Evidence suggests that cells comprising the neurovascular unit (NVU) cooperatively mediate neuronal development, survival and regeneration. The aim of this study was to test whether cerebrovascular cells, endothelial cells and pericytes, produce neurotrophins and play neuroprotective roles during hypoxic insults. We examined the expression of neurotrophins and their receptors in cultured human cerebral microvascular endothelial cells and pericytes, astrocytes and the rat neuronal cell line PC12. Differentiated PC12 cells expressed TrkA, the NGF receptor, which was significantly upregulated by hypoxia at 1% O(2) and regulated neuronal survival. Both pericytes and astrocytes expressed three neurotrophins, i.e. NGF, BDNF and NT-3, while TrkB and TrkC, specific receptors for BDNF and NT-3, were expressed in astrocytes, but not pericytes. In response to hypoxia, among the neurotrophins expressed in pericytes and astrocytes only NT-3 expression was significantly upregulated in pericytes. Treatment of astrocytes with NT-3 significantly activated Erk1/2 and increased the expression of NGF both at mRNA and protein levels. The MEK1 inhibitor U0126 or siRNA-mediated knockdown of TrkC abolished the NT-3-induced upregulation of NGF in astrocytes. Taken together, cerebral microvascular pericytes and astrocytes are potent producers of neurotrophins in the NVU. In response to hypoxia, pericytes increase NT-3 production, which induces astrocytes to increase NGF production through the TrkC-Erk1/2 pathway. The interplay between pericytes and astrocytes through neurotrophins in the NVU may play an important role in neuronal survival under hypoxic conditions.