Acellular dermal matrix has enhanced implant-based reconstruction and remains useful in immediate prosthetic breast reconstruction. It is associated, however, with higher rates of postoperative seroma and infection. Careful patient selection, choice of tissue expander/implant volume, and postoperative management are warranted to optimize overall reconstructive outcome.

Cell surface heparan sulfate proteoglycans, such as the syndecans, are required for cellular responses to heparin-binding growth factors and extraceflular matrix components. Expression of syndecan-1 and -4 is induced in mesenchymal cells during wound repair in the mouse, consistent with a role for syndecans in regulating cell proliferation and migration in response to these effectors. Here we show that wound fluid contains inductive activity that mimics the in vivo induction in time of appearance, specifcity for mesenchymal cells, and selectivity for syndecan-1 and -4. We have purified and synthesized a 4.8-kDa proline-rich protein from wound fluid that reproduces this induction of syndecan-1 and -4 in cultured cells. This peptide, identicai to the antibacterial peptide PR-39, is released into the wound by the cellular infirate and induces syndecan expression at the same peptide concentrations that lyse bacteria. These results indicate that wounds contain a multifunctional protein that induces mammalian cells to express cell surface heparan sulfate proteoglycans as part of the wound repair process and that kills bacteria as part of a nonimmune defense mechanism.

Appearance of heparin-binding EGF-like growth factor in wound fluid as a response to injury (epidermal growth Communicated by Judah Folkman, January 4, 1993 (received for review January 3, 1992) ABSTRACTWound fluid was obtained from porcine partial-thickness excisional wounds and analyzed for heparinbinding growth factors. Two heparin-binding growth factor activities were detected, a relatively minor one that was eluted from a heparin affinity column with 0.65 M NaCi and a major one that was eluted with 1.1 M NaCI. These activities were not present in wound fluid 1 hr after injury but appeared 1 day after injury, were maximal 2-3 days after injury, and were not detectable by 8 days after injury. The heparin-binding growth factor eluted with 0.65 M NaCl was identified as a plateletderived growth factor (PDGF)-like activity by the use ofspecific anti-PDGF neutralizing antibodies. The heparin-binding growth factor eluted with 1.1 M NaCl was shown to be structurally related to heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF) by several criteria, including binding to heparin affinity columns and elution with 1.1 M NaCl, competition with the binding of 125I-EGF to the EGF receptor, triggering phosphorylation of the EGF receptor, immunodetection on a Western blot, and stimulation of fibroblast and keratinocyte growth. It was concluded that HB-EGF is a major growth factor component of wound fluid and, since it is mitogenic for fibroblasts and keratinocytes, that it might play an important role in wound healing.

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The strong evidence pointing to the favorable healing of wounds in a wet or moist environment compared to dry treatment will extend the clinical indications for this treatment. Further advances are required to elucidate by which means this microenvironment can be optimized to improve the healing outcome.

This article describes the first (to our knowledge) tetracycline-inducible regulatory system that demonstrates that the tetracycline repressor (tetR) alone, rather than tetR-mammalian cell transcription factor fusion derivatives, can function as a potent trans-modulator to regulate gene expression in mammalian cells. With proper positioning of tetracycline operators downstream of the TATA element and of human epidermal growth factor (hEGF) as a reporter, we show that gene expression from the tetracycline operator-bearing hCMV major immediate-early enhancer-promoter (pcmvtetO) can be regulated by tetR over three orders of magnitude in response to tetracycline when (1) the reporter was cotransfected with tetR-expressing plasmid in transient expression assays, and (2) the reporter unit was stably integrated into the chromosome of a tetR-expressing cell line. This level of tetR-mediated inducible gene regulation is significantly higher than that of other repression-based mammalian cell transcription switch systems. In an in vivo porcine wound model, close to 60-fold tetR-mediated regulatory effects were detected and it was reversed when tetracycline was administered. Collectively, this study provides a direct implementation of this tetracycline-inducible regulatory switch for controlling gene expression in vitro, in vivo, and in gene therapy.

Proteoglycans have been shown in vitro to bind multiple components of the cellular microenvironment that function during wound healing. To study the composition and function of these molecules when derived from an in vivo source, soluble proteoglycans released into human wound fluid were characterized and evaluated for influence on fibroblast growth factor-2 activity. Immunoblot analysis of wound fluid revealed the presence of syndecan-1, syndecan-4, glypican, decorin, perlecan, and versican. Sulfated glycosaminoglycan concentrations ranged from 15 to 65 g/ml, and treatment with chondroitinase B showed that a large proportion of the glycosaminoglycan was dermatan sulfate. The total glycosaminoglycan mixture present in wound fluid supported the ability of fibroblast growth factor-2 to signal cell proliferation. Dermatan sulfate, and not heparan sulfate, was the major contributor to this activity, and dermatan sulfate bound FGF-2 with K d ‫؍‬ 2.48 M. These data demonstrate that proteoglycans released during wound repair are functionally active and provide the first evidence that dermatan sulfate is a potent mediator of fibroblast growth factor-2 responsiveness.

This report details the transfer of a human epidermal growth factor (hEGF) expression plasmid to porcine partial-thickness wound keratinocytes by particle-mediated DNA transfer (Accell). After gene transfer an external sealed fluid-filled wound chamber was used to protect the wound, provide containment of the exogenous DNA and expres peptide, and permit saing of the wound fluid. Analysis of wound fluid for hEGF and total protein, an indicator of reformation of the epithelal barrier, showed that wounds bombarded with the hEGF plasmid exhibited a 190-fold increase in EGF concentration and healed 20% (2.1 days) earier than the controls. EGF concentrations in wound fluid persisted over the entire 10-day monitored period, decreasing from 200 pg/ml to 25 pg/ml over the first 5 days. Polymerase chain reaction results showed that plasmid DNA was present in the wound for at least 30 days. These findings demonstrate the possible utility of in vivo gene transfer to enhance epidermal repair.