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ABSTRACT: The majority of the population experience successful wound-healing outcomes; however, 1-3% of those aged over 65 years experience delayed wound healing and wound perpetuation. These hard-to-heal wounds contain degraded and dysfunctional extracellular matrix (ECM); yet, the integrity of this structure is critical in the processes of normal wound healing. Here, we evaluated a novel synthetic matrix protein for its ability to act as an acellular scaffold that could replace dysfunctional ECM. In this regard, the synthetic protein was subjected to adsorption and diffusion assays using collagen and human dermal tissues; evaluated for its ability to influence keratinocyte and fibroblast attachment, migration and proliferation and assessed for its ability to influence in vivo wound healing in a porcine model. Critically, these experiments demonstrate that the matrix protein adsorbed to collagen and human dermal tissue but did not diffuse through human dermal tissue within a 24-hour observation period, and facilitated cell attachment, migration and proliferation. In a porcine wound-healing model, significantly smaller wound areas were observed in the test group compared with the control group following the third treatment. These data provide evidence that the synthetic matrix protein has the ability to function as an acellular scaffold for wound-healing purposes.
International Wound Journal 04/2013; · 1.46 Impact Factor
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ABSTRACT: Presently, global rates of skin cancers induced by ultraviolet radiation (UVR) exposure are on the rise. In view of this, current knowledge gaps in the biology of photocarcinogenesis and skin cancer progression urgently need to be addressed. One factor that has limited skin cancer research has been the need for a reproducible and physiologically-relevant model able to represent the complexity of human skin. This review outlines the main currently-used in vitro models of UVR-induced skin damage. This includes the use of conventional two-dimensional cell culture techniques and the major animal models that have been employed in photobiology and photocarcinogenesis research. Additionally, the progression towards the use of cultured skin explants and tissue-engineered skin constructs, and their utility as models of native skin's responses to UVR are described. The inherent advantages and disadvantages of these in vitro systems are also discussed.
Experimental Dermatology 03/2012; 21(6):404-10. · 3.54 Impact Factor
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Zee Upton,
Hilary J Wallace,
Gary K Shooter, Derek R van Lonkhuyzen,
Sim Yeoh-Ellerton,
Erin A Rayment,
Jacqui M Fleming,
Daniel Broszczak,
Douglas Queen,
R Gary Sibbald,
David I Leavesley,
Michael C Stacey
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ABSTRACT: Several different advanced treatments have been used to improve healing in chronic wounds, but none have shown sustained success. The application of topical growth factors (GFs) has displayed some potential, but the varying results, high doses and high costs have limited their widespread adoption. Many treatments have ignored the evidence that wound healing is driven by interactions between extracellular matrix proteins and GFs, not just GFs alone. We report herein that a clinical Good Manufacturing Practice-grade vitronectin:growth factor (cVN:GF) complex is able to stimulate functions relevant to wound repair in vitro, such as enhanced cellular proliferation and migration. Furthermore, we assessed this complex as a topical wound healing agent in a single-arm pilot study using venous leg ulcers, as well as several 'difficult to heal' case studies. The cVN:GF complex was safe and re-epithelialisation was observed in all but 1 of the 30 patients in the pilot study. In addition, the case studies show that this complex may be applied to several ulcer aetiologies, such as venous leg ulcers, diabetic foot ulcers and pressure ulcers. These findings suggest that further evaluation is warranted to determine whether the cVN:GF complex may be an effective topical treatment for chronic wounds.
International Wound Journal 10/2011; 8(5):522-32. · 1.46 Impact Factor
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ABSTRACT: Numerous studies have reported links between insulin-like growth factors (IGFs) and the extra-cellular matrix protein vitronectin (VN). We ourselves have reported that IGF-I binds to VN via IGF-binding proteins (IGFBPs) to stimulate HaCaT and MCF-7 cell migration. Here, we detail the functional evaluation of IGFBP-1, -2, -3, -4 and -6 in the presence and absence of IGF-I and VN. The data presented here, combined with our prior data on IGFBP-5, suggest that IGFBP-3, -4 and -5 are the most effective at stimulating cell migration in combination with IGF-I and VN. In addition, we demonstrate that different regions within IGFBP-3 and -4 are critical for complex formation. Furthermore, we examine whether multi-protein complexes of IGF-I and IGFBPs associated with fibronectin and collagen IV are also able to enhance functional biological responses.
Growth factors (Chur, Switzerland) 10/2010; 28(5):359-69. · 2.47 Impact Factor
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ABSTRACT: IGF-I can bind to the extracellular matrix protein vitronectin (VN) through the involvement of IGF-binding proteins-2, -3, -4, and -5. Because IGF-I and VN have established roles in tumor cell dissemination, we were keen to investigate the functional consequences of the interaction of IGF-I, IGF binding proteins (IGFBPs), and VN in tumor cell biology. Hence, functional responses of MCF-7 breast carcinoma cells and normal nontumorgenic MCF-10A mammary epithelial cells were investigated to allow side-by-side comparisons of these complexes in both cancerous and normal breast cells. We demonstrate that substrate-bound IGF-I-IGFBP-VN complexes stimulate synergistic increases in cellular migration in both cell types. Studies using IGF-I analogs determined this stimulation to be dependent on both heterotrimeric IGF-I-IGFBP-VN complex formation and the involvement of the IGF-I receptor (IGF-IR). Furthermore, the enhanced cellular migration was abolished on incubation of MCF-7 and MCF-10A cells with function blocking antibodies directed at VN-binding integrins and the IGF-IR. Analysis of the signal transduction pathways underlying the enhanced cell migration revealed that the complexes stimulate a transient activation of the ERK/MAPK signaling pathway while simultaneously producing a sustained activation of the phosphatidylinositide 3-kinase/AKT pathway. Experiments using pharmacological inhibitors of these pathways determined a requirement for phosphatidylinositide 3-kinase/AKT activation in the observed response. Overexpression of wild type and activated AKT further increases substrate-bound IGF-I-IGFBP-VN-stimulated migration. This study provides the first mechanistic insights into the action of IGF-I-IGFBP-VN complexes and adds further evidence to support the involvement of VN-binding integrins and their cooperativity with the IGF-IR in the promotion of tumor cell migration.
Endocrinology 04/2008; 149(3):1075-90. · 4.46 Impact Factor
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ABSTRACT: Complexes comprised of IGF-I, IGF-binding proteins and the ECM protein vitronectin (VN) stimulate cell migration and growth and can replace the requirement for serum for the ex vivo expansion of cells, as well as promote wound healing in vivo. Moreover, the activity of the complexes is dependent on co-activation of the IGF-I receptor and VN-binding integrins. In view of this we sought to develop chimeric proteins able to recapitulate the action of the multiprotein complex within a single molecular species. We report here the production of two recombinant chimeric proteins, incorporating domains of VN linked to IGF-I, which mimic the functions of the complex. Further, the activity of the chimeric proteins is dependent on co-activation of the IGF-I- and VN-binding cell surface receptors. Clearly the use of chimeras that mimic the activity of growth factor:ECM complexes, such as these, offer manufacturing advantages that ultimately will facilitate translation to cost-effective therapies.
Growth Factors 11/2007; 25(5):295-308. · 1.65 Impact Factor
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ABSTRACT: Insulin-like growth factor-1 (IGF-I) can bind to the extracellular matrix protein vitronectin (VN) through the involvement of IGF-binding proteins-2, -3, -4 and -5. Since IGF-I and VN have established roles in tumour cell dissemination, we were keen to investigate the functional consequences of the interaction of IGF-I, IGFBPs and VN in tumour cell biology. Hence, functional responses of MCF-7 breast carcinoma cells and "normal" non-tumourgenic MCF-10A mammary epithelial cells were investigated to allow side-by-side comparisons of these complexes in both cancerous and normal breast cells. We demonstrate that substrate-bound IGF-I:IGFBP:VN complexes stimulate synergistic increases in cellular migration in both cell types. Studies using IGF-I analogues determined this stimulation to be dependent upon both heterotrimeric IGF-I:IGFBP:VN complex formation and the involvement of the IGF-1R. Furthermore, the enhanced cellular migration was abolished upon incubation of MCF-7 and MCF-10A cells with function blocking antibodies directed at VN-binding integrins and the IGF-IR. Analysis of the signal transduction pathways underlying the enhanced cell migration revealed that the complexes stimulate a transient activation of the ERK/MAPK signalling pathway, while simultaneously producing a sustained activation of the PI3-K/AKT pathway. Experiments using pharmacological inhibitors of these pathways determined a requirement for PI3-K/AKT activation in the observed response. Overexpression of wild type and activated AKT further increases substrate-bound IGF-I:IGFBP:VN-stimulated migration. This study provides the first mechanistic insights into the action of IGF-I:IGFBP:VN complexes and adds further evidence to support the involvement of VN-binding integrins and their co-operativity with the IGF-IR in the promotion of tumour cell migration.
