Cell adhesion and migration are essential for embryonic development, tissue regeneration, but also for tumor development. The physical link between the extracellular matrix (ECM) and the actin cytoskeleton is mainly mediated by receptors of the integrin family. Through signals transduced upon integrin ligation to ECM proteins, this family of proteins plays key roles in regulating tumor growth and metastasis as well as tumor angiogenesis. During melanoma development, changes in integrin expression, intracellular control of integrin functions and signals perceived from integrin ligand binding impact upon the ability of tumor cells to interact with their environment and enable melanoma cells to convert from a sessile, stationary to a migratory and invasive phenotype. Antagonists of several integrins are now under evaluation in clinical trials to determine their potential as therapeutics for malignant melanoma and other kinds of cancer.

A key central stage of wound healing requires neovascularization of the wound base granulation tissue. In the adult, neovascularization is now known to occur by both angiogenesis and vasculogenesis. Understanding the biology of these 2 processes offers promising new therapeutic options for patients who suffer from chronic, nonhealing ischemic wounds. The authors review the current literature on the processes of angiogenesis and vasculogenesis and how it relates to wound healing.

In this article, we describe an image analysis strategy with improved power for tracking longitudinal amyloid-β (Aβ) PET changes and evaluating Aβ-modifying treatments. Methods: Our aims were to compare the power of template-based cerebellar, pontine, and cerebral white matter reference regions to track 24-mo florbetapir standardized uptake value (SUV) ratio (SUVR) changes; to relate those changes to 24-mo clinical declines; and to evaluate Aβ-modifying treatments in Aβ-positive (Aβ1) and Aβ-negative (Aβ−) patients with probable Alzheimer dementia (pAD), in patients with mild cognitive impairment (MCI), in cognitively normal controls (NCs), and in cognitively normal apolipoprotein E4 (APOE4) carriers and noncarriers. We used baseline and follow-up (∼24 mo) florbetapir PET scans from 332 Aβ1 and Aβ− subjects participating in the multicenter Alzheimer's Disease Neuroimaging Initiative. Each of the proposed analyses included 31 pAD patients, 187 MCI patients, and 114 NCs. Cerebral-to-white matter, cerebellar, and pontine SUVRs were characterized in terms of their longitudinal variability; their power to track longitudinal fibrillar Aβ increases in Aβ1 and Aβ− subgroups and cognitively normal APOE4 carriers and noncarriers; the sample sizes needed to detect attenuated accumulation of or clearance of fibrillar Aβ accumulation in randomized clinical trials; and their ability to relate 24-mo fibrillar Aβ increases to clinical declines. Results: As predicted, cerebral-to-white matter SUVR changes were significantly less variable and had significantly greater power to detect 24-mo fibrillar Aβ increases and evaluate Aβ-modifying treatment effects in Aβ1 pAD, MCI, and NC subjects and cognitively normal APOE4 carriers. They were also distinguished by the ability to detect significant associations between 24-mo Aβ increases and clinical declines. Conclusion: A cerebral white matter reference region may improve the power to track longitudinal fibrillar Aβ increases, to characterize their relationship to longitudinal clinical declines, and to evaluate Aβ-modifying treatments in randomized clinical trials. PET ligands (1-15) have made it possible to investigate the fibrillar amyloid-b (Ab) burden in living people; to clarify its relationship to the dementia, mild cognitive impairment (MCI), and preclinical stages of Alzheimer disease (AD); to characterize the extent to which cross-sectional measurements predict subsequent clinical declines; to track longitudinal changes; and to help evaluate Ab-modifying treatments.Researchers commonly compute a semiquantitative cerebral-toreference region standardized uptake value ratio (SUVR) using PET counts from a cerebral region of interest (ROI) and from a whole cerebellar (2,3), cerebellar gray matter (10), or pontine (8) reference ROI that is thought to be relatively devoid of fibrillar Ab. Less commonly, researchers compute a cerebral-to-reference region distribution volume ratio or other quantitative measures using longer, dynamically acquired PET scans and the same cerebral and refe...

BackgroundAutopsy series commonly report a high percentage of coincident pathologies in demented patients, including patients with a clinical diagnosis of dementia of the Alzheimer type (DAT). However many clinical and biomarker studies report cases with a single neurodegenerative disease. We examined multimodal biomarker correlates of the consecutive series of the first 22 Alzheimer’s Disease Neuroimaging Initiative autopsies. Clinical data, neuropsychological measures, cerebrospinal fluid Aβ, total and phosphorylated tau and α-synuclein and MRI and FDG-PET scans.ResultsClinical diagnosis was either probable DAT or Alzheimer’s disease (AD)-type mild cognitive impairment (MCI) at last evaluation prior to death. All patients had a pathological diagnosis of AD, but only four had pure AD. A coincident pathological diagnosis of dementia with Lewy bodies (DLB), medial temporal lobe pathology (TDP-43 proteinopathy, argyrophilic grain disease and hippocampal sclerosis), referred to collectively here as MTL, and vascular pathology were present in 45.5%, 40.0% and 22.7% of these patients, respectively. Hallucinations were a strong predictor of coincident DLB (100% specificity) and a more severe dysexecutive profile was also a useful predictor of coincident DLB (80.0% sensitivity and 83.3% specificity). Occipital FDG-PET hypometabolism accurately classified coincident DLB (80% sensitivity and 100% specificity). Subjects with coincident MTL showed lower hippocampal volume.ConclusionsBiomarkers can be used to independently predict coincident AD and DLB pathology, a common finding in amnestic MCI and DAT patients. Cohorts with comprehensive neuropathological assessments and multimodal biomarkers are needed to characterize independent predictors for the different neuropathological substrates of cognitive impairment.

Endothelial progenitor cells (EPC) are known to contribute to wound healing, but the physiologic triggers for their mobilization are often insufficient to induce complete wound healing in the presence of severe ischemia. EPC trafficking is known to be regulated by hypoxic gradients and induced by vascular endothelial growth factor-mediated increases in bone marrow nitric oxide (NO). Hyperbaric oxygen (HBO) enhances wound healing, although the mechanisms for its therapeutic effects are incompletely understood. It is known that HBO increases nitric oxide levels in perivascular tissues via stimulation of nitric oxide synthase (NOS). Here we show that HBO increases bone marrow NO in vivo thereby increasing release of EPC into circulation. These effects are inhibited by pretreatment with the NOS inhibitor L-nitroarginine methyl ester (L-NAME). HBO-mediated mobilization of EPC is associated with increased lower limb spontaneous circulatory recovery after femoral ligation and enhanced closure of ischemic wounds, and these effects on limb perfusion and wound healing are also inhibited by L-NAME pretreatment. These data show that EPC mobilization into circulation is triggered by hyperoxia through induction of bone marrow NO with resulting enhancement in ischemic limb perfusion and wound healing. STEM CELLS 2006;24:2309 -2318

Ischemic wound healing remains an unsolved problem with no previously identified molecular target for therapeutic intervention. This study demonstrates that VEGF-C overexpression by fibroblasts stimulates multiple biologic processes known to impact wound healing, such as collagen constriction, capillary sprouting, and EPC invasion and migration through extracellular matrix. Most ischemic wounds fail to heal and frequently lead to major limb amputation. Available cytokine ointments are ineffective, and revascularization is often not technically feasible. Even when these procedures are accomplished, many ischemic wounds frequently still do not heal because of multifactorial tissue level impairments in the fibroblastic and neovascularization responses at the wound base. Our findings identify an important role for two novel tissue level targets, dermis-derived fibroblasts and VEGF-C, in collagen constriction, angiogenesis, and postnatal vasculogenesis from BMD EPCs. Thus the findings are particularly relevant to the unsolved clinical problem of ischemic wound healing.

MIA (melanoma inhibitory activity) has been identified as a small protein secreted from malignant melanoma cells, which interacts with extracellular matrix proteins including fibronectin. Here, we show that MIA negatively regulates the activity of the mitogen-activated protein kinase pathway in malignant melanoma. Using far Western blotting and co-immunoprecipitation we searched for MIA-binding cell surface proteins. We found that MIA interacts with integrin ␣4␤1 and ␣5␤1, leading to down-regulation of integrin activity and reduction of mitogen-activated protein kinase signaling. These findings also suggest that MIA may play a role in tumor progression and the spread of malignant melanomas via mediating detachment of cells from extracellular matrix molecules by modulating integrin activity. Inhibiting MIA functions in vivo may therefore provide a novel therapeutic strategy for metastatic melanoma disease.We have previously identified MIA (melanoma inhibitory activity), an 11-kDa protein secreted into the tissue culture supernatant from malignant melanoma cells (1). MIA expression in vivo correlates with progressive malignancy of melanocytic tumors (2). Additionally, in recent studies we detected enhanced MIA protein levels specifically in the serum of patients with metastatic melanomas (3). In vitro studies revealed a role for MIA in supporting the invasive and migratory potential of melanoma cells. In vivo studies in two animal model systems confirmed the importance of MIA in melanoma metastasis. MIA expression levels parallel closely the capability of melanoma cells to form metastases in syngeneic animals (4, 5).Three-dimensional analyses of MIA by multidimensional NMR (6 -8) or x-ray crystallography (9) indicate that MIA defines a novel family of secreted proteins that adopt an SH3 domain-like fold in solution. Furthermore, NMR spectra revealed that MIA interacts with peptides matching to type III human fibronectin repeats that are closely related to ␣4␤1 integrin-binding sites (6). These data support a model in which MIA regulates attachment to specific components of the extracellular matrix. Based on these results and on the observation that MIA alters melanoma cell morphology, we determined that MIA treatment results in cell detachment by decreasing interactions between melanoma cells and extracellular matrix molecules (10). The study presented here was performed to find additional MIA-interacting proteins and to identify signaling pathways regulated by MIA. EXPERIMENTAL PROCEDURESCell Lines and Culture Conditions-The melanoma cell lines Mel Im and Mel Ei, have been described in detail previously (11). The cell line Mel Ei was derived from a primary cutaneous melanoma, and the cell line Mel Im was derived from a metastasis of malignant melanoma. To establish fibronectin-deficient fibroblast-like cells, primary embryonic fibroblasts were isolated from E13.5 fibronectin (flox/flox) embryos and immortalized by retroviral transduction of the SV-40 large T antigen and cloned (12). Subsequently, two clonal lines...

Adult bone marrow-derived mesenchymal stem cells (MSCs) are able to differentiate into myofibroblasts and be recruited into wound lesions and contribute to wound healing. The cellular and molecular mechanism responsible for MSC trafficking and differentiation, however, are poorly understood. Local resting resident fibroblasts are activated after injury and play a critical role in recruiting MSCs. We investigated the role of platelet derived growth factor-B-activated fibroblasts (PDGF-B-aFBs) in regulating recruitment, migration and differentiation of MSCs from GFP transgenic mice in an in vitro wound healing assay and a novel three-dimensional (3D) model. PDGF-B-aFBs caused significant increases in MSCs migration velocity compared to control as demonstrated by time-lapse photography in an in vitro wound healing assay. Consistently, invasion/ migration of MSCs into 3D collagen gels was enhanced in the presence of PDGF-B-aFbs. In addition, PDGF-B-aFBs induced differentiation of MSCs into myofibroblast. The regulatory effects of PDGF-B-aFBs are likely to be mediated by basic fibroblast growth factor (bFGF) and epithelial neutrophil activating peptide-78 (ENA-78 or CXCL5) as protein array analysis indicated an elevated levels of these two soluble factors in culture supernatant of PDGF-B-aFBs. Blocking antibodies against bFGF and CXCL5 were able to inhibit both trafficking and differentiation of MSCs into 3D collagen gels while supplement of exogenous bFGF and/or CXCL5 promoted invasion/migration of MSCs into 3D collagen gels. Our results reveal that PDGF-B-aFBs play a key role in recruitment/migration and differentiation of MSCs and implicate a bFGF-and CXCL5-dependent mechanism in mediating these effects. KeywordsFibroblasts; Platelet derived growth factor-B (PDGF-B); basic fibroblast growth factor (bFGF); endothelial neutrophil activating peptide-78 (ENA-78) or CXCL5; bone marrow-derived mesenchymal stem cells; wound healing Correspondence to: Omaida C. Velazquez.