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Int J Clin Exp Pathol 2012;5(1):1-11

Original Article
Transgenic overexpression of keratinocyte-specific VEGF and Ang1 in combination
promotes wound healing under nondiabetic but not diabetic conditions

Candace M Loyd, Doina Diaconu, Wen Fu, Gregory N Adams, Dorothy A Knutsen, Julie A Wolfram, Thomas S McCormick, Nicole L Ward

Department of Dermatology, Case Western Reserve University, Cleveland, OH 44106, USA; University Hospitals, Case Medical Center,
Cleveland, OH  44106, USA.

Received November 29, 2011; accepted December 14, 2011; Epub January 1, 2012; published January 15, 2012

Abstract: VEGF and Angiopoietin (Ang)1 are growth factors that independently improve wound healing outcomes. Using a tet-repressible
mouse model coupled with streptozotocin-induced diabetes, we examined wound healing in diabetic and nondiabetic mice engineered to
overexpress keratinocyte-specific(K5) VEGF, Ang1 or Ang1-VEGF combined. All nondiabetic mice healed more rapidly than their diabetic
counterparts; however overexpression of VEGF, Ang1 or the combination failed to improve wound closure under diabetic conditions.
Conversely, under nondiabetic conditions, combining Ang1 and VEGF resulted in rapid wound closure. Molecular analyses of diabetic and
nondiabetic K5-Ang1-VEGF skin revealed no differences in VEGF expression but an 80% decrease in Ang1 under diabetic conditions,
suggesting an integral role for Ang1.  Nondiabetic K5-Ang1 mice healed more quickly and had significant increases in granulation tissue and a
60% decrease in re-epithelialization 7 days after wounding. Furthermore, Ang1 stimulated primary mouse keratinocytes showed significantly
less migration into a wound bed in an in vitro wound healing bioassay and had decreased pMAPK, pNFκB, pAkt, and pStat3 signaling. These
data suggest that combined Ang1-VEGF overexpression cannot overcome diabetes-induced delays in wound healing but is efficacious under
nondiabetic conditions possibly via Ang1-mediated delays in re-epithelialization and enhancement of granulation tissue formation, thereby
allowing more rapid secondary intention healing.

Keywords: streptozotocin, angiogenesis, re-epithelialization, wound healing, transgenic mouse, keratinocyte, skin

Address all correspondence to:
Dr. Nicole L. Ward, PhD
Case Western Reserve University
Departments of Dermatology and Neuroscience
BRB519, 10900 Euclid Ave
Cleveland, OH  44106
Phone: 216-368-1111
Fax: 216-368-0212
E-mail: nicole.ward@case.edu