Keratinocyte growth factor induces granulation tissue in ischemic dermal wounds. Importance of epithelial-mesenchymal cell interactions.
BACKGROUND
Keratinocyte growth factor acts specifically on epithelial cells and is presumed to play an important role in tissue repair.


OBJECTIVE
To examine the wound-healing effects of keratinocyte growth factor under hypoxic conditions in vivo and in vitro.


METHODS
Dermal ulcers were created in the ischemic ears of 40 anesthetized young female rabbits. Either recombinant keratinocyte growth factor (rKGF) or buffer was applied to each wound. Wounds were bisected and analyzed histologically at days 7 and 10 after wounds were created. For the in vitro study, normal keratinocytes were treated with rKGF (20 ng/mL) and cultured under hypoxic (3.5% oxygen) conditions. The conditioned media were collected at 48 and 72 hours.


METHODS
The amount of epithelial growth and deposition of granulation tissue were measured in all wounds. The amount of transforming growth factor alpha in keratinocyte-conditioned media was measured by using a sensitive radioimmunoassay. A proliferation assay of dermal fibroblasts, treated with conditioned media, was also performed under 3.5% oxygen culture conditions.


RESULTS
The rKGF (range, 5-40 micrograms per wound) that was applied significantly increased new epithelium by greater than 70% (P = .03) at days 7 and 10 after wounds were created. A significant increase in new granulation tissue formation (170%) was also observed in rKGF-treated wounds at day 10, at a dose of 40 micrograms per wound (P < .002). The amount of transforming growth factor alpha protein in the conditioned media that were treated with rKGF (20 ng/mL) increased by 26.8% and 171% at 48 and 72 hours, respectively, over that of controls. The conditioned media from rKGF-treated keratinocytes, grown for 72 hours, resulted in a 51% increase in the proliferation of primary rabbit dermal fibroblasts.


CONCLUSIONS
Keratinocyte growth factor enhances the wound-healing process of ischemic ulcers, indicating that epithelial-mesenchymal cell interactions are critical for the healing of wounds under ischemic conditions and possibly under normal conditions as well.
Wu
L
L
Department of Surgery, Northwestern University Medical School, Chicago, Ill, USA.
Pierce
G F
GF
Galiano
R D
RD
Mustoe
T A
TA
D000818:Animals; D002455:Cell Division; D002478:Cells, Cultured; D003470:Culture Media; D004847:Epithelial Cells; D005260:Female; D051526:Fibroblast Growth Factor 10; D051523:Fibroblast Growth Factor 7; D005346:Fibroblast Growth Factors; D005347:Fibroblasts / Q000166:cytology; D006097:Granulation Tissue; D006133:Growth Substances / Q000494:pharmacology* / Q000627:therapeutic use; D007511:Ischemia; D015603:Keratinocytes / Q000187:drug effects*; D008648:Mesoderm / Q000166:cytology; D011817:Rabbits; D011863:Radioimmunoassay; D012883:Skin Ulcer / Q000188:drug therapy*; D016211:Transforming Growth Factor alpha / Q000032:analysis; D014945:Wound Healing / Q000187:drug effects*
D003470:Culture Media; D051526:Fibroblast Growth Factor 10; D006133:Growth Substances; D016211:Transforming Growth Factor alpha; D051523:Fibroblast Growth Factor 7; D005346:Fibroblast Growth Factors