Oxygenation state of the wound tissue is known to influence wound outcomes by a number of mechanisms ranging from enabling oxidative metabolism, fighting infection, hydroxylating collagen, generating nitric oxide, and generating reactive oxygen species which may support redox signaling. The etiology of chronic ischemic wounds is generally multi-factorial of which hypoxia caused by underlying peripheral vasculopathy is a common factor. Hypoxia is generally viewed as being angiogenic. So why does the ischemic wound not close even faster? Although hypoxia may have favorable effects on endothelial cells, the hypoxia-inducible transcription factor HIF specifically induces growth arrest of keratinocytes compromising wound closure. HIF1? is abundant in basal keratinocytes at the wound edge and causes growth arrest. Our observation directly implicates hypoxia-inducible microRNA (miRNA) or hypoxamir in arresting keratinocyte function. Specifically, we noted that the hypoxamir miR-210 silences target genes which would arrest growth/migration as well as repress mitochondrial metabolism in keratinocytes. In both mice and chronic wound patients, ischemic wounds showed elevated miR-210 levels. Next, we screened for miR-210 dependent pathways that would impair wound re-epithelialization. We studied the candidate pathways that emerged from murine studies for their relevance to human chronic wounds. Those specific pathways that emerged from murine studies and were successfully validated using human chronic wound-edge tissue were selected for study in this proposal. microRNA (miR or miRNA) represents a class of recently discovered non-coding (nc) genes that are of such extraordinary significance in human health and disease. Whether a set of coding gene would be functional or silenced is decided by specific miRs targeting that set of genes. As we seek to take the study of tissue oxygenation and wound healing to the future, we have chosen to focus on unveiling the significance of hypoxamir miR-210 in regulating wound closure.
Three aims are proposed:
Aim 1 : Characterize mechanisms underlying miR-210 dependent compromised wound re-epithelialization of ischemic wounds. ?1.1 Ischemic wound-associated elevation of miR-210 silences ISCU1/2 inhibiting mitochondrial metabolism;?1.2 Elevated miR-210 silences E2F3 causing p53 activation and inhibition of keratinocyte proliferation;?1.3 miR-210 up-regulation silences ACVR1B impeding keratinocyte migration.
Aim 2 : Determine molecular mechanisms underlying induction of miR-210 by ischemia;Central hypothesis: Wound ischemia induces keratinocyte miR-210 via HIF1? and lactate. ?2.1 HIF-1?/ARNT and novel co- activators drive hypoxia-induced miR-210 expression;?2.2 Lactate drives miR-210 expression.
Aim 3 : Elevated miR-210 in the epidermis of ischemic human wound edge tissue is associated with poor healing outcome in a setting of standard clinical care. We propose a prospective longitudinal study where adult non-diabetic patients with chronic leg ulcers visiting the OSU Comprehensive Wound Center will be enrolled.

Public Health Relevance

In the United States, skin wounds affect 6.5 million patients placing a major burden, estimated at US$25 billion annually, on society. Ischemia or limited blood supply to the wound tissue is a major complicating factor. The proposed project aims at understanding of why the ischemic wound does not close with special emphasis on specific novel genes called hypoxamirs which are elevated in wound tissue suffering from poor oxygen supply.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
2R01GM077185-05A1
Application #
8514903
Study Section
Special Emphasis Panel (ZRG1-SBIB-X (02))
Program Officer
Somers, Scott D
Project Start
2007-08-01
Project End
2017-04-30
Budget Start
2013-05-01
Budget End
2014-04-30
Support Year
5
Fiscal Year
2013
Total Cost
$299,001
Indirect Cost
$104,001
Name
Ohio State University
Department
Surgery
Type
Schools of Medicine
DUNS #
832127323
City
Columbus
State
OH
Country
United States
Zip Code
43210
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Das, Amitava; Ghatak, Subhadip; Sinha, Mithun et al. (2016) Correction of MFG-E8 Resolves Inflammation and Promotes Cutaneous Wound Healing in Diabetes. J Immunol 196:5089-100
Ghatak, Subhadip; Li, Jilong; Chan, Yuk C et al. (2016) AntihypoxamiR functionalized gramicidin lipid nanoparticles rescue against ischemic memory improving cutaneous wound healing. Nanomedicine 12:1827-1831
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Ghatak, Subhadip; Chan, Yuk Cheung; Khanna, Savita et al. (2015) Barrier Function of the Repaired Skin Is Disrupted Following Arrest of Dicer in Keratinocytes. Mol Ther 23:1201-10
Sen, Chandan K (2015) Expanding horizons of cellular plasticity in regenerative medicine. Am J Pathol 185:2592-5
Sen, Chandan K; Ghatak, Subhadip (2015) miRNA control of tissue repair and regeneration. Am J Pathol 185:2629-40
Gnyawali, Surya C; Barki, Kasturi G; Mathew-Steiner, Shomita S et al. (2015) High-resolution harmonics ultrasound imaging for non-invasive characterization of wound healing in a pre-clinical swine model. PLoS One 10:e0122327
Banerjee, Jaideep; Das Ghatak, Piya; Roy, Sashwati et al. (2015) Silver-zinc redox-coupled electroceutical wound dressing disrupts bacterial biofilm. PLoS One 10:e0119531

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