Nerve growth factor promotes reparative angiogenesis and inhibits endothelial apoptosis in cutaneous wounds of Type 1 diabetic mice.
OBJECTIVE
The neurotrophin nerve growth factor (NGF) is pro-angiogenic and facilitates wound repair. The present study was conducted to (i) assess the statement of NGF system components in diabetic wounds and (ii) evaluate whether NGF supplementation could prevent impairment of wound neoangiogenesis by diabetes.


METHODS
Skin wounds were produced in the interscapular region of streptozotocin-induced diabetic mice. NGF (1 microg per day in PBS) or vehicle was applied onto the ulcers for 3 days after punching. Non-diabetic mice were used as controls.


RESULTS
In wounds of untreated diabetic mice, endogenous levels of immunoreactive NGF were lower than those in wounds of non-diabetic mice ( p<0.01). Immunohistochemical analysis showed down-regulation of tyrosine kinase receptor-A (TrkA) and up-regulation of p75 receptor in granulation tissue microvasculature. Local NFG administration prevented diabetes-induced expressional alterations, enhanced reparative capillarisation ( p<0.01), and accelerated wound closure ( p<0.01). This was associated with a three-fold increase in endothelial cell proliferation ( p<0.01), while apoptosis was reduced by 50% ( p<0.05). Quantitative RT-PCR documented a 5.5-fold increase in the expression of vascular endothelial growth factor-A (VEGF-A) by exogenous NGF in diabetic tissues ( p<0.01). In in vitro preparations of human endothelial cells from derma, NGF increased the release of immunoreactive VEGF-A, and reduced high-glucose-induced apoptosis ( p<0.05), the latter effect being inhibited by a VEGF-A receptor-2 antagonist.


CONCLUSIONS
Diabetic ulcers display distinct alterations in reparative angiogenesis and in the expression of NGF and its receptors. NGF supplementation corrects endogenous liabilities, facilitates vascular regeneration, and suppresses endothelial apoptosis seemingly via VEGF-A. Our findings unravel new mechanisms responsible for NGF reparative action.
Graiani
G
G
Department of Pathology, University of Parma, Italy.
Emanueli
C
C
Desortes
E
E
Van Linthout
S
S
Pinna
A
A
Figueroa
C D
CD
Manni
L
L
Madeddu
P
P
D000279:Administration, Cutaneous; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D003921:Diabetes Mellitus, Experimental / Q000150:complications; D003922:Diabetes Mellitus, Type 1 / Q000150:complications*; D004195:Disease Models, Animal; D004353:Drug Evaluation, Preclinical / Q000379:methods; D042783:Endothelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D015870:Gene Expression / Q000187:drug effects; D005947:Glucose / Q000009:adverse effects / Q000037:antagonists & inhibitors / Q000378:metabolism; D006801:Humans; D007558:Italy; D008297:Male; D051379:Mice; D018919:Neovascularization, Physiologic / Q000187:drug effects* / Q000502:physiology; D020932:Nerve Growth Factor / Q000235:genetics / Q000378:metabolism / Q000627:therapeutic use*; D017475:Receptors, Nerve Growth Factor / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D012883:Skin Ulcer / Q000150:complications* / Q000188:drug therapy* / Q000473:pathology; D042461:Vascular Endothelial Growth Factor A / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D014945:Wound Healing / Q000187:drug effects / Q000502:physiology
D017475:Receptors, Nerve Growth Factor; D042461:Vascular Endothelial Growth Factor A; C467480:vascular endothelial growth factor A, mouse; D020932:Nerve Growth Factor; D005947:Glucose