Expression constructs encoding a full-length cDNA encoding the human epidermal growth factor receptor, or reporter gene for green fluorescent protein or luciferase were coated onto gold particles and driven into porcine skin using a gene gun delivery system. Strategies for epidermal growth factor receptor boosting were tested in two types of wounds. For grafted wounds, intact porcine skin was pretreated by the introduction of the epidermal growth factor receptor expression construct 24 hours before its harvesting as a split-thickness skin graft. Partial-thickness excisional wound beds (donor sites) were transfected at the time of their creation. Wound healing parameters were subsequently tested in the presence or absence of excess epidermal growth factor ligand. Initial distributions of gene gun delivered gold particles as well as luciferase expression levels suggested that optimal skin penetrations and expression levels were achieved at 500 psi for intact epidermis and 300 psi for exposed wound beds. At 2 days after gene delivery, visualization of green fluorescent protein by fluorescence microscopy showed focal expression of green fluorescent protein at the advancing epithelial outgrowths found at wound edges or surviving epithelial remnants. Green fluorescent protein expression appeared transient since no green fluorescent protein was noted in specimens removed at 4 days after injury. Northern blot analysis on mRNA isolated from wounds 2 days after introduction of epidermal growth factor receptor coated gold particles by gene gun confirmed the expression of the human epidermal growth factor receptor transgene in both skin grafts and excisional wounds. Skin grafts showed subsequent biological responses to the introduction of excessive epidermal growth factor receptor as well as expression of the human epidermal growth factor receptor construct within healing epidermis. While control autografts (reporter gene treated, epidermal growth factor alone, placebo formula, no treatment) showed few 5'-bromodeoxyuridine-labeled cells, epidermal growth factor receptor autografts showed 5'-bromodeoxyuridine labeling of nearly every basal cell. Favorable wound healing outcomes were also shown within excisional wounds following in vivo boosting of epidermal growth factor receptor. Four days after receiving epidermal growth factor receptor particle growth factor receptor transgene. Application of topical epidermal growth factor ligand resulted in the highest percentage of resurfacing. Maximal re-epithelialization was noted in wound beds receiving both receptor boosting and excessive daily epidermal growth factor ligand. A modest increase in the thickness of the granulation tissue followed gene therapy with epidermal growth factor receptor. In summary these in vivo data suggest that it is possible to boost in vivo expression of a tyrosine kinase receptor during wound repair. Increased epidermal growth factor receptor expression has an integral impact on cell proliferation, rates of resurfacing and dermal components and merits consideration as a possible therapeutic agent.

Animals↗

PubMedDate not supplied

Floral-color polymorphism in Ipomoea purpurea: biased inheritance of the dark allele is not a general explanation for its maintenance.

A previous investigation reported the existence in a single population of the morning glory (Ipomoea purpurea) of non-Mendelian inheritance at the W locus influencing flower color. In addition, it was shown that the magnitude of biased inheritance in that population was sufficient to maintain a floral-color polymorphism at that locus at frequencies approximating those observed in natural populations. The current investigation was undertaken to determine whether this biased inheritance was characteristic of other I. purpurea populations, and thus whether it provides a general explanation for maintenance of the polymorphism. The current study found no evidence for biased inheritance in two additional polymorphic populations examined. Non-Mendelian inheritance thus seems unlikely to constitute a general explanation for the maintenance of this floral-color polymorphism in l. purpurea.

Alleles↗