Quantitative analysis of inflammatory cell influx, procollagen type I synthesis, and collagen cross-linking in incisional wounds: influence of PDGF-BB and TGF-beta 1 therapy.
Platelet-derived growth factor (PDGF-BB homodimer) and transforming growth factor-beta 1 (TGF-beta 1) are potent wound-healing hormones that accelerate incisional repair. To identify more precisely and quantitatively the stage(s) of wound healing influenced by growth-factor therapy, we investigated the three sequential tissue repair processes--inflammatory cell influx, intracellular procollagen type I (PC-I) synthesis, and collagen cross-linking--in recombinant growth factor--treated wounds. Using newly developed automated, quantitative image-analysis techniques, we observed that PDGF-BB markedly augmented the directed migration of macrophages into wounds during the first week after wounding and triggered and earlier and more sustained influx of PC-I--containing fibroblasts into the wound when compared with results in TGF-beta 1-treated or control wounds (p = 0.015 at day 2; p = 0.007 at day 21). In contrast, automated image analysis revealed TGF-beta 1-treated wound fibroblasts had a nearly twofold increase in intracellular levels of PC-I protein when compared with PDGF-BB-treated or control wound fibroblasts (p = 0.004 at day 4). However, the influence of TGF-beta 1 was transient, and the longer duration of PDGF-BB activity suggested a later influence, perhaps on the collagen remodeling phase, which is ultimately required for increased wound strength. To address this possibility, collagen cross-linking in growth factor-treated wounds was inhibited by beta-aminoproprionitrile (BAPN) treatment, and wound breaking strength was analyzed. Both PDGF-BB and TGF-beta 1 continued to enhance repair in BAPN-treated rats, indicating that they do not function primarily at the level of collagen cross-linking. Thus, PDGF-BB appears to enhance the inflammatory phase of wound healing to indirectly trigger PC-I synthesis, whereas TGF-beta 1 quantitatively enhances PC-I synthesis directly, accounting for their differing duration of activities within healing wounds.
Pierce
G F
GF
Department of Experimental Pathology, Amgen Inc., Thousand Oaks, CA 91320.
Brown
D
D
Mustoe
T A
TA
D000629:Aminopropionitrile / Q000494:pharmacology; D000818:Animals; D003094:Collagen / Q000096:biosynthesis*; D005347:Fibroblasts / Q000378:metabolism; D007249:Inflammation / Q000473:pathology; D008264:Macrophages / Q000502:physiology; D009000:Monocytes / Q000502:physiology; D009504:Neutrophils / Q000502:physiology; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D011347:Procollagen / Q000096:biosynthesis*; D051381:Rats; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D014945:Wound Healing
D010982:Platelet-Derived Growth Factor; D011347:Procollagen; D016212:Transforming Growth Factor beta; D000629:Aminopropionitrile; D003094:Collagen