Introduction. In chronic wounds (diabetic foot, bedsores), hypoxia hampers efficient healing by altering the balances between matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) secreted by surrounding tissues, including endothelium. Impaired chronic wounds could be targeted by new effective oxygenating drugs, such as O2-Loaded Nanobubbles (OLNs). Here, hypoxia effects on MMP/TIMP secretion from human microvascular dermal endothelium, along with possible therapeutic role of dextran-shelled decafluoropentane-containing OLNs, were investigated. Methods. HMEC-1 cells were incubated in serum-free medium for 24 h in normoxia and hypoxia, in the absence/presence of OLNs, O2-free nanobubbles (OFNs) or O2-saturated solution (OSS). Thereafter, citotoxicity was evaluated by measuring lactate dehydrogenase activity; cell supernatant MMP-2, MMP-9, TIMP-1, and TIMP-2 protein levels were measured by enzyme-linked immunosorbent assay and gelatin zimography; cell invasion abilities were evaluated through Matrigel assay. Results. OLNs, OFNs, and OSS did not display significant cytotoxicity on HMEC-1, and did not affect cell viability. In normoxia, cells released MMP-2, TIMP-1 and TIMP-2, but not MMP-9. Hypoxia strongly impaired MMP/TIMP balances by increasing MMP-2, reducing TIMP-1, and not affecting TIMP-2 release; consequently, cell invasion abilities resulted compromised. OLNs abrogated all hypoxia effects, restoring normoxic phenotype. Neither OSS nor OFNs did mimic OLN effects, specifically dependent on time-sustained O2 diffusion from OLN core. Conclusion. Collectively, these data show that dextran-shelled/decafluoropentane-containing OLNs counteract hypoxia-dependent dysregulation of endothelial MMP/TIMP balances, supporting that topical administration of exogenous O2, properly encapsulated in nanobubble formulations, might promote healing of chronic wounds. Acknowledgements. Work supported by funding from Ateneo-Compagnia di San Paolo (ORTO11CE8R 2011).
Nanotechnology and wound healing: dextran-shelled/decafluoropentane-containing oxygen-loaded nanobubbles counteract hypoxia-dysregulated MMP/TIMP balances in human microvascular dermal endothelium.
KHADJAVI, AMINA;GIRIBALDI, Giuliana;GUIOT, Caterina;PRATO, Mauro
2013-01-01
Abstract
Introduction. In chronic wounds (diabetic foot, bedsores), hypoxia hampers efficient healing by altering the balances between matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) secreted by surrounding tissues, including endothelium. Impaired chronic wounds could be targeted by new effective oxygenating drugs, such as O2-Loaded Nanobubbles (OLNs). Here, hypoxia effects on MMP/TIMP secretion from human microvascular dermal endothelium, along with possible therapeutic role of dextran-shelled decafluoropentane-containing OLNs, were investigated. Methods. HMEC-1 cells were incubated in serum-free medium for 24 h in normoxia and hypoxia, in the absence/presence of OLNs, O2-free nanobubbles (OFNs) or O2-saturated solution (OSS). Thereafter, citotoxicity was evaluated by measuring lactate dehydrogenase activity; cell supernatant MMP-2, MMP-9, TIMP-1, and TIMP-2 protein levels were measured by enzyme-linked immunosorbent assay and gelatin zimography; cell invasion abilities were evaluated through Matrigel assay. Results. OLNs, OFNs, and OSS did not display significant cytotoxicity on HMEC-1, and did not affect cell viability. In normoxia, cells released MMP-2, TIMP-1 and TIMP-2, but not MMP-9. Hypoxia strongly impaired MMP/TIMP balances by increasing MMP-2, reducing TIMP-1, and not affecting TIMP-2 release; consequently, cell invasion abilities resulted compromised. OLNs abrogated all hypoxia effects, restoring normoxic phenotype. Neither OSS nor OFNs did mimic OLN effects, specifically dependent on time-sustained O2 diffusion from OLN core. Conclusion. Collectively, these data show that dextran-shelled/decafluoropentane-containing OLNs counteract hypoxia-dependent dysregulation of endothelial MMP/TIMP balances, supporting that topical administration of exogenous O2, properly encapsulated in nanobubble formulations, might promote healing of chronic wounds. Acknowledgements. Work supported by funding from Ateneo-Compagnia di San Paolo (ORTO11CE8R 2011).
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