Background: Despite refinements in radiotherapy, radiation-impaired wound healing continues to be a major source of postoperative morbidity with few treatment options. The application of polypeptide growth factors has been investigated in both the clinical and laboratory settings. The authors used a novel sustained-release delivery system to examine the effect of transforming growth factor (TGF)-beta and fibroblast growth factor (FGF) on radiation-impaired wound healing in a rodent model.
Methods: Eighty Sprague-Dawley rats underwent dorsal skin surface irradiation of 2500 cGy using a medical linear accelerator producing energy of 6 MeV followed by creation of a full-thickness skin incision. Six groups of 16 animals underwent either sham irradiation (irradiation control); irradiation only; irradiation and unimpregnated delivery system only; or irradiation and either TGF-beta, FGF, or TGF-beta plus FGF combined. Four animals from each group were euthanized at 4, 7, 14, and 28 days, and the harvested specimens underwent ultimate tensile strength testing and histologic evaluation.
Results: All five irradiated groups had significantly lower ultimate tensile strength than the sham-irradiated control group at all time points (p < 0.05), thus validating the authors' model of radiation-impaired wound healing. Functional analysis demonstrated that all three growth factor-treated groups had significantly higher tensile strengths than either of the untreated irradiated groups at 14 days after wounding (p < 0.05). Histologic evaluation of the irradiated groups revealed increased cellularity and more organized collagen architecture of all treated groups when compared with the untreated groups, with the most pronounced differences seen at 7 days and 14 days after wounding.
Conclusions: This study effectively demonstrates that TGF-beta and FGF act individually and synergistically when delivered locally by means of a sustained release system to improve ultimate tensile strength in an acute postirradiation impaired wound-healing model.