The Wound Healing Process

Transvaginal evisceration after hysterectomy: Is vaginal cuff closure associated with a reduced risk?

OBJECTIVE

To evaluate the overall incidence of transvaginal evisceration following hysterectomy and to assess the risk associated with indication, route of surgery, age and vaginal cuff closure technique.

MATERIALS AND METHODS

A database was used to identify all patients undergoing hysterectomy from 1995 to 2001 at our institution and all the patients admitted for vaginal evisceration during the same period. Each vaginal evisceration was analyzed for time of onset, trigger event, presenting symptoms, details of prolapsed organs and type of repair surgery.

RESULTS

Of the 3593 patients enrolled in the study, 63.5% underwent abdominal hysterectomy, 33.0% vaginal hysterectomy, and 3.5% laparoscopic hysterectomy. Ten patients (0.28%) presented to the emergency room with vaginal evisceration. No statistical differences in evisceration rates were seen according to the route of surgery. No differences were found between the 1440 patients who had closure of the vaginal cuff and the 2153 who had an unclosed cuff closure technique.

CONCLUSIONS

Our data suggest that, in young patients, sexual intercourse is to be considered the main trigger event before the complete healing of the vaginal cuff while, in elderly patients, the evisceration is a spontaneous event. Uterine prolapse was not associated with a higher rate and the route of surgery or vaginal cuff closure technique did not influence the dehiscence rate.

Bradykinin B2receptor antagonism attenuates inflammation, mast cell infiltration and fibrosis in remote myocardium after infarction in rats

Bradykinin may interfere with myocardial remodelling by promoting inflammation and mast cell activation or, alternatively, by counteracting angiotensin II-dependent collagen accumulation. The aim of the present study was to investigate the role of bradykinin B2 receptor antagonism in inflammatory and mast cell infiltration, fibroplasia and fibrosis accumulation following myocardial infarction (MI). Myocardial infarction was produced by the ligature of the left coronary artery in male Wistar rats that were 10 weeks of age. Immediately after MI, rats received the B2 receptor antagonist Hoe140 (0.5 microg/kg per min, s.c.) or saline over a period of 3 days, 1 week or 4 weeks, constituting three separate groups and their respective controls. Coronal myocardial tissue sections underwent haematoxylin and eosin, Giemsa and picrosirius red staining, as well as immunohistochemistry for alpha-smooth muscle actin (SMA). Morphometric studies were undertaken in three different myocardial regions: MI, remote non-infarcted subendocardium (non-MI SE) and remote non-infarcted interventricular septum (non-MI IVS). The MI size was comparable between Hoe140-treated groups and their respective controls (day 3: 42 +/- 4%, n = 8, vs 43 +/- 3%, n = 6; week 1: 37 +/- 5%, n = 5, vs 39 +/- 2%, n = 5; week 4: 35 +/- 3%, n = 9, vs 36 +/- 3%, n = 7). At day 3, Hoe140 treatment reduced inflammatory cell reaction within the MI (585 +/- 59 vs 995 +/- 170 cells/mm2; P = 0.02), non-MI SE (77 +/- 12 vs 214 +/- 57 cells/mm2; P = 0.02) and non-MI IVS (93 +/- 16 vs 135 +/- 14 cells/mm2; P = 0.03) regions. Mast cells were reduced within the non-MI IVS region (0.8 +/- 0.1 vs 2.5 +/- 0.4 cells/mm2; P = 0.006), but not within the MI region. In non-MI SE, mast cells were rarely found. At week 1, Hoe140 treatment reduced alpha-SMA-positive myofibroblast infiltration within the MI (2535 +/- 383 vs 5636 +/- 968 cells/mm2; P = 0.01) and non-MI SE (222 +/- 33 vs 597 +/- 162 cells/mm2; P = 0.03) regions. In the non-MI IVS region, alpha-SMA-positive myofibroblasts were rarely found. At week 4, Hoe140 treatment reduced collagen volume fraction within the MI (37 +/- 4 vs 53 +/- 4%; P = 0.03), non-MI SE (1.3 +/- 0.2 vs 2.6 +/- 0.3%; P = 0.001) and non-MI IVS (1.1 +/- 0.2 vs 1.8 +/- 0.2%; P = 0.01) regions. Bradykinin promotes inflammation, fibroplasia and fibrosis after MI. Mast cells may have a role in fibrosis deposition through a bradykinin-related mechanism.

Interleukin-1alpha-induced proteolytic activation of metalloproteinase-9 by human skin

BACKGROUND

Increased activity of matrix metalloproteinase-9 (MMP-9) has been well documented in many diseases associated with inflammation, such as chronic wounds, bullous pemphigoid, liver failure, and tumor metastases. The mechanism for the proteolytic activation of pro-MMP-9 in human tissue still remains unknown.

METHODS

We investigated this mechanism through reconstitution of an inflammatory condition in normal human skin, and epidermal and dermal cells derived from skin. Normal human skin was cultured with exogenous cytokines associated with inflammation and tissue repair. MMP-9 induction and activation were measured, and potential mechanisms were probed by inhibitors.

RESULTS

Pathophysiologic concentrations of interleukin (IL)-1alpha rapidly induced pro-MMP-9 synthesis by human skin. In contrast, IL-1-induced activation of pro-MMP-9 was a slow process, which required 3 days. Tumor growth factor-beta induced pro-MMP-9 but failed to promote activation of the precursor. When the skin was stimulated with the combination of tumor growth factor-beta and IL-1alpha, substantial induction and activation of pro-MMP-9 occurred. This IL-1 induced activation of pro-MMP-9 was observed in intact skin but not in isolated dermal fibroblasts or keratinocytes. IL-1-induced activation of pro-MMP-9 was inhibited by chymostatin, a chymotrypsinlike proteinase inhibitor. Furthermore, IL-1alpha decreased tissue inhibitor of metalloproteinase 1 without changing MMP-9 activator activity.

CONCLUSIONS

The proteolytic activation of pro-MMP-9 in skin inflammatory diseases likely occurs via a pathway including IL-1alpha. The activation is mediated by downregulation of tissue inhibitor of MMP-1 and involves an as yet unidentified chymotrypsinlike proteinase.

Applications of Doppler Imaging in the Musculoskeletal System

Pathological conditions affecting the musculoskeletal system often result in alterations of regional blood flow. The assessment of a Doppler signal in inflammatory or infective processes complements the grayscale findings, helping to evaluate the severity of disease. Doppler imaging can also be used to determine therapeutic response or help guide injections. In addition, Doppler interrogation enables vascular characterization of solid masses. The presence of a Doppler signal can also help differentiate solid from cystic lesions. This article reviews the wide range of applications for Doppler imaging of the musculoskeletal system.

The Effect of AgK114 on Wound Healing

AgK114 is a newly isolated membrane-associated protein which is expressed on keratinocytes. Its expression is restricted to dermal sheath cells near sebaceous glands in normal skin. However, it is transiently induced by UV exposure or injury stimulation (Tatefuji T. et al., Biol. Pharm. Bull., 27, 1742-1749, 2004). Thus, the expression pattern of AgK114 suggested its potential role in wound healing response. We report here that expression of AgK114 is induced in the initial 24 h at the edge keratinocytes during keratinocyte migration, followed by disappearance once epithelialization is completed in the murine excisional wound model. We also demonstrate that exogenous recombinant mouse AgK114FL promoted wound healing process. Mouse AgK114FL up-regulated pro-matrix-metalloproteinase-9, vascular endothelial growth factor, transforming growth factor-beta, IL-6, and IL-1beta production in the early stage of wound tissue. Moreover, mouse AgK114FL induced the matrix-metalloproteinase-9 activity of wound fibroblasts prepared from impaired skin in the presence of proinflammatory cytokines. These results suggest that the AgK114 participates in the wound response during the healing process, and promotes wound repair.

The pathophysiology of wound repair

The equine practitioner who is presented with a wounded horse should fully understand the physiologic mechanisms involved in repair so as to design an appropriate treatment plan. In the following articles of this issue,experienced authors share their thoughts on the management of specific injuries, and the reader should benefit from acquisition of knowledge about the different phases of healing as well as the cytokines that regulate them,because these data dictate the approach to follow, particularly in com-plicated wounds, such as those afflicted by chronic inflammation and/or an excessive proliferative response.

Factors that affect equine wound repair

The rate and outcome of wound healing are determined by many factors,some of which are already in effect when the horse is first presented to the veterinarian. A thorough understanding of wound healing principles,coupled with clear client communication, should enable the practitioner to minimize the number of additional factors that may exacerbate the initial situation.

Second-intention repair in the horse and pony and management of exuberant granulation tissue

Second-intention repair is faster in ponies than in horses and faster in body wounds than in limb wounds. To a large extent, the differences between horses and ponies can be explained by differences in the local inflammatory response, which are a result of the functional capacity of leukocytes. In ponies, leukocytes produce more inflammatory mediators,resulting in better local defense, faster cellular debridement, and a faster transition to the repair phases, with more wound contraction. In horses,leukocytes produce fewer mediators, initiating a weak inflammatory response, which becomes chronic. This inhibits wound contraction and gives rise to the formation of exuberant granulation tissue. The anatomic environment that influences the inflammatory response and wound contraction most probably determines the differences between body and limb wounds. In body wounds, better perfusion results in faster initiation of the inflammatory phase. The weaker local resistance results in a greater degree of contraction. In limb wounds, particularly of horses, the initial inflammatory response is weak and wound contraction is restricted. Both factors give rise to chronic inflammation, which further inhibits wound contraction and promotes exuberant granulation tissue. The high incidence of exuberant granulation tissue in limb wounds of horses can thus be explained by the chronicity of the inflammatory response as well as by the common use of bandages during treatment. Chronic inflammation is often not recognized as a cause of exuberant granulation tissue. It must be prevented and treated to promote the healing process. Bandages and casts stimulate the formation of exuberant granulation tissue; however, they are advantageous in many respects and play an important role in support of the overall healing process.

Acute vocal fold wound healing in a rabbit model

Several authors have eloquently described the characteristics of vocal fold scar, a long-term consequence of vocal fold injury. However, events in the acute stage of mucosal injury, which lead up to fibrosis, have been largely overlooked. The current study describes acute events with regard to mucosal re-formation in a rabbit model. Vocal fold injury was induced surgically. A fibrinous clot was present 1 day after injury. Massive cellular infiltration was noted on day 3, and complete epithelial coverage was achieved by day 5. Also, neo-matrix deposition was noted as early as 5 days after injury, and more mature collagen was seen by day 7. The general timetable described in the current study can contribute to the experimental foundation for the development of regenerative models of healing in the vocal folds. Most notably, the proliferation phase of wound healing appears to occur approximately 3 days after injury, indicating a critical time for intervention. Manipulation and/or alteration of naturally occurring neo-matrix deposition and organization may yield improved biophysical function of the injured vocal fold.

Epidermis promotes dermal fibrosis: role in the pathogenesis of hypertrophic scars

Hypertrophic scarring is a pathological process characterized by fibroblastic hyperproliferation and by excessive deposition of extracellular matrix components. It has been hypothesized that abnormalities in epidermal-dermal crosstalk explain this pathology. To test this hypothesis, a tissue-engineered model of self-assembled reconstructed skin was used in this study to mimic interactions between dermal and epidermal cells in normal or pathological skin. These skin equivalents were constructed using three dermal cell types: normal wound (Wmyo) or hypertrophic wound (Hmyo) myofibroblasts and normal skin fibroblasts (Fb). Epidermis was reconstructed with normal skin keratinocytes (NK) or hypertrophic scar keratinocytes (HK). In the absence of keratinocytes, Hmyo formed a thicker dermis than Wmyo. When seeded with NK, the dermal thickness of Hmyo (121.2 +/- 31.4 microm vs 196.2 +/- 27.8 microm) and Fb (43.7 +/- 7.1 microm vs 83.6 +/- 16.3 microm) dermis was significantly (p < 0.05) reduced, while that of Wmyo (201.5 +/- 15.7 microm vs 160.7 +/- 21.1 microm) was increased. However, the presence of HK always induced significantly thicker dermis formation than observed with NK (Wmyo: 238.8 +/- 25.9 microm; Hmyo: 145.5 +/- 22.4 microm; Fb: 74.2 +/- 11.2 microm). These results correlated with collagen and MMP-1 secretion and with cell proliferation, which were increased when keratinocytes were added, except for the collagen secretion of Hmyo and Fb in the presence of NK. The level of dermal apoptosis was not different when epidermis was added to the dermis (<1% in each category). These observations strongly suggest that hypertrophic scar keratinocytes play a role in the development of pathological fibrosis by influencing the behaviour of dermal cells.

Effects of acute diabetes on rat cutaneous wound healing

INTRODUCTION:: Diabetes mellitus is a chronic hyperglycaemic disorder. Complicated metabolic mechanisms and increased incidence of infections are clinical hallmarks, mostly associated with its chronicity. There is little information about the early pathological processes in diabetes. The objective of our study was to evaluate the healing process during early phases of experimental diabetes on rat skin. METHODS:: Alloxan induced diabetic rats were used. Non-injected animals were used as control. Punch byopsies on dorsal skin had histopathological evaluation of the healing areas made on days 1, 3 and 7 post-surgery. RESULTS:: The results showed that: (1) in diabetics, the inflammation, the initial healing phase, has a slow beginning and tends to last longer; and (2) diabetic animals showed lower density of neutrophils in healing areas up to 3 days after surgery, and in addition, after day 3, when the neutrophils should leave the healing area, and be replaced by macrophages, compared to controls, diabetic animals showed higher numbers of neutrophils. PRINCIPAL CONCLUSION:: Although diabetes is a chronic progressive disease, acute diabetes can be associated to subclinical alterations, and responsible for deficiencies in defense cells and in repair tissue failures.

The role of angiopoietins in the development of endothelial cells from cord blood CD34+ progenitors

Circulating endothelial progenitors contribute to neovascularization at sites of injury and tumorigenesis in postnatal life. Yet, the molecular mechanisms initiating the endothelial developmental program of these precursors remain elusive. Here we provide evidence that endothelial development from progenitors circulating in human cord blood requires angiopoietins, a set of growth factors also involved in vascular branching during embryogenesis. We show that cord blood cells with the potential for endothelial development reside in a CD34(+)CD11b+ subset capable of autonomously producing and binding angiopoietins. Functionally, endogenous angiopoietin-1 regulates initial endothelial cell commitment, whereas angiopoietin-2 enhances expansion of the endothelial cell progeny. These findings suggest a role for angiopoietins as regulators of endothelial development from circulating progenitors and imply a function of angiopoietins at distinct developmental steps in postnatal angiogenesis.

Markers of wound healing in vocal fold secretions from patients with laryngeal pathology

This study seeks to determine the ability of enzyme-linked immunosorbent assays of vocal fold secretions to detect and describe the inflammatory response in the vocal folds. Vocal fold and palatal secretions were collected during operation from patients with a range of vocal fold disorders and from control patients. The secretions were subjected to assays for interleukin-1beta, prostaglandin E2, and transforming growth factor beta. The results indicate a differential expression of mediators associated with the wound healing cascade in the vocal folds. The prostaglandin E2 levels clearly differentiated vocal fold secretions associated with laryngeal disease versus control sites. Furthermore, the interleukin-1beta concentrations were significantly elevated in subjects with epithelial lesions of the vocal folds as opposed to lesions of the lamina propria. Although still in its infancy, such analysis may ultimately hold scientific and clinical utility in the study and management of patients with vocal fold disease.

ET-1 inhibits B-16 murine melanoma cell migration by decreasing K+ currents

Cell migration is mediated by ion channels and transporters, and plays crucial roles in a variety of physiological and pathological processes. Previously, our studies have shown that a Ca(2+)-regulated K(+) current exists in B-16 murine melanoma cells, and that endothelin-1 (ET-1) inhibits the K(+) current via a PKC-dependent pathway. In the present study, patch-clamp whole-cell recording and transwell migration assays were used to examine the effects of ET-1 on B-16 murine melanoma cell migration. ET-1 (100 nM in the injection pipette and 10 nM in the incubation medium) decreased the K(+) current amplitude by 33.0 +/- 2.5% and inhibited migration of B-16 cells by 57.4 +/- 9.4%. Similarly, the Ca(2+)-regulated K(+) channel blockers, BaCl(2) and quinidine, decreased the K(+) current by 20.5 +/- 1.0% and 36.6 +/- 1.2%, respectively, and slowed migration of B-16 melanoma cells by 37.1 +/- 8.6% and 42.7 +/- 8.8%, respectively. The effect of ET-1 on the K(+) current and cell migration was simulated by ET-3. In contrast, the K(+) channel opener, diclofenac, increased the K(+) current by 128.8 +/- 11.7%, 257.4 +/- 35.8% at concentrations of 1 and 5 mM, respectively. Likewise, the migration of B-16 murine melanoma cells dramatically increased by 75.6 +/- 12.7% in the presence of 100 microM diclofenac in incubation medium. Furthermore, the ET-1- and ET-3-induced inhibition of K(+) current and migration was abrogated by diclofenac. In the presence of diclofenac, ET-1 only reduced the K(+) current amplitude by 10.6 +/- 1.1%, and slowed B-16 cell migration by only 10.8 +/- 8.9%. The results suggest that the K(+) channel-dependent migration of B-16 melanoma cells is modulated by ET-1. Cell Motil.

Orchestrating wound healing: assessing and preparing the wound bed

PURPOSE

To provide an overview of the steps needed to prepare the wound bed for healing.

TARGET AUDIENCE

This continuing-education activity is intended for physicians and nurses with an interest in learning about the process for preparing the wound bed for healing.

LEARNING OBJECTIVES

After reading the article and taking the test, the participant will be able to: 1. Describe the anatomy and physiology of the skin. 2. Describe the wound healing process, the local and systemic factors that may impair healing, and the parameters that assess the wound status. 3. Describe the steps in the process to prepare the wound bed for healing.

Can medical hypnosis accelerate post-surgical wound healing? Results of a clinical trial

Although medical hypnosis has a long history of myriad functional applications (pain reduction, procedural preparation etc.), it has been little tested for site-specific effects on physical healing per se. In this randomized controlled trial, we compared the relative efficacy of an adjunctive hypnotic intervention, supportive attention, and usual care only on early post-surgical wound healing. Eighteen healthy women presenting consecutively for medically recommended reduction mammaplasty at an ambulatory surgery practice underwent the same surgical protocol and postoperative care following preoperative randomization (n = 6 each) to one of the three treatment conditions: usual care, 8 adjunctive supportive attention sessions, or 8 adjunctive hypnosis sessions targeting accelerated wound healing. The primary outcome data of interest were objective, observational measures of incision healing made at 1,7 weeks postoperatively by medical staff blind to the participants' group assignments. Data included clinical exams and digitized photographs that were scored using a wound assessment inventory (WAI). Secondary outcome measures included the participants' subjectively rated pain, perceived incision healing (VAS Scales), and baseline and post-surgical functional health status (SF-36). Analysis of variance showed the hypnosis group's objectively observed wound healing to be significantly greater than the other two groups', p < .001, through 7 postoperative weeks; standard care controls showed the smallest degree of healing. In addition, at both the 1 and 7 week post-surgical observation intervals, one-way analyses showed the hypnosis group to be significantly more healed than the usual care controls, p < 0.02. The mean scores of the subjective assessments of postoperative pain, incision healing and functional recovery trended similarly. Results of this preliminary trial indicate that use of a targeted hypnotic intervention can accelerate postoperative wound healing and suggest that further tests of using hypnosis to augment physical healing are warranted.

Laser scar revision: comparison study of 585-nm pulsed dye laser with and without intralesional corticosteroids

BACKGROUND

Hypertrophic scars affect 1.5% to 4.5% of the general population and remain notoriously difficult to eradicate because of the high recurrence rates and the incidence of side effects associated with treatment. Pulsed dye laser (PDL) treatment and intralesional corticosteroids have individually been reported to be effective in reducing hypertrophic scar bulk and symptoms.

OBJECTIVE

To determine whether combination PDL and intralesional corticosteroid treatment produces better hypertrophic scar improvement than PDL treatment alone.

METHODS

Bilateral hypertrophic inframammary scars in 22 females were randomly assigned to receive treatment with 585-nm PDL alone or in combination with intralesional corticosteroid. Clinical evaluations and scar pliability scores were determined before each of the two treatment sessions and 6 weeks after the final treatment. Histologic evaluation of skin biopsies obtained before and after treatment was performed in four patients.

RESULTS

All scars showed clinical improvement with increased pliability and decreased symptoms (pruritus) after each of the two treatments. Clinical improvement scores were not significantly better with the concomitant use of corticosteroids. Side effects were limited to mild purpura and transient hyperpigmentation. Decreased sclerosis was seen in scars after PDL treatment (with or without concomitant corticosteroids).

CONCLUSIONS

Treatment of hypertrophic inframammary scars with 585-nm PDL irradiation alone effected substantial clinical and histologic improvement. The adjunctive use of intralesional corticosteroids did not significantly enhance clinical outcome except in those scars that were most symptomatic.

The identification of novel wound-healing genes through differential display

Effective methods to identify novel genes in complicated dynamic tissue processes are needed in molecular biology research. Traditional techniques primarily target known genes and are inefficient in the pursuit of unknown genes. Here we describe the use of a modified differential display polymerase chain reaction (DD-PCR) protocol for the identification of genes differentially expressed in wound healing. Full-thickness dorsal wounds were made on 35 adult rats, followed by wound harvest at 12 hours, 24 hours, 3 days, 5 days, 7 days, 10 days, and 14 days after injury. Modified DD-PCR was performed and gene fragments displaying definite changes during wound healing were cloned and sequenced. Gene fragments from DD-PCR were compared with available gene bank database sequences. Specific primer PCR was used to confirm DD-PCR expression patterns. As a result, over 1000 gene fragments were amplified by DD-PCR, 35 of which demonstrated distinct differences during repair. Cloning and sequencing of 13 of these gene fragments revealed that some were homologous to several characterized genes with previously unsuspected roles in repair, whereas others were completely novel genes with no known function. Specific primer PCR further confirmed expression of six of these 13 gene fragments. Only one of the 13 cloned fragments, later identified as interleukin-1beta, had well-recognized associations with tissue injury. Other fragments corresponded to various genes involved in cellular processes such as differentiation, proliferation, exocytosis, and myofibril assembly. No prior studies have linked them to wound healing. We have demonstrated that modified DD-PCR can be used to effectively identify novel genes differentially expressed during repair. Because DD-PCR allows for the simultaneous amplification of multiple arbitrary transcripts, it is a powerful genetic screening tool for complicated dynamic tissue processes, particularly when multiple, limited-sized samples are involved.

Early healing events in a porcine model of contaminated wounds: effects of nanocrystalline silver on matrix metalloproteinases, cell apoptosis, and healing

A porcine model of wound healing was employed to examine the impact of nanocrystalline silver-coated dressings on specific wound healing events. Full-thickness wounds were created on the backs of pigs, contaminated with an experimental inoculum containing Pseudomonas aeruginosa, Fusobacterium sp., and coagulase-negative staphylococci, and covered with dressing products either containing silver or not. Nanocrystalline silver-coated dressings promoted rapid wound healing, particularly during the first several days post-injury. Healing was characterized by rapid development of well vascularized granulation tissue that supported tissue grafting 4 days post-injury, unlike control dressed wounds. The proteolytic environment of wounds treated with nanocrystalline silver was characterized by reduced levels of matrix metalloproteinases. Matrix metalloproteinases have been shown to be present in chronic ulcers at abnormally high levels, as compared with acute wounds, and may contribute to the nonhealing nature of these wounds. Cellular apoptosis occurred at a higher frequency in the nanocrystalline silver-treated wounds than in wounds dressed with other products. The results suggest that nanocrystalline silver may play a role in altering or compressing the inflammatory events in wounds and facilitating the early phases of wound healing. These benefits are associated with reduced local matrix metalloproteinase levels and enhanced cellular apoptosis.

Age-related changes in wound healing

Evidence for age-related effects on wound healing have been derived for the most part from empirical observations without adjustment for confounders other than age. Age-related changes in the structure and function of the skin do occur. Some of these changes result from chronic solar radiation exposure rather than chronological age per se. The tensile strength of wounds, accumulation of wound healing factors and rate of wound closure have all been examined in relation to chronological aging. However, the clinical impact of these changes in acute wound healing appears to be small. Poor healing in chronic wounds is more often related to comorbid conditions rather than age alone. Since the majority of these chronic wounds occur in elderly populations, this has contributed to the conclusion that aging itself may influence healing. Progress in understanding the role that growth factors play in wound healing and the ability to synthesise adequate quantities of these factors for clinical use has led to clinical trials evaluating their use in wound healing. The results of these studies, with the possible exception of those in diabetic wounds, have been disappointing. Insight into the wound healing process indicates that growth factors interact during wound healing in a sequential and orderly process. Improved wound healing may require different clinical designs or the use of these factors in a precisely timed sequential administration.

Adenovirus vector-mediated transfer of the vascular endothelial growth factor cDNA to healing abdominal fascia enhances vascularity and bursting strength in mice with normal and impaired wound healing

BACKGROUND

We hypothesized that adenovirus-mediated transfer of the vascular endothelial growth factor (VEGF121) complementary DNA (cDNA) to murine laparotomy fascial wounds would enhance vascularity and bursting strength.

METHODS

Microfibrillar collagen sponges saturated with adenovirus (Ad) vectors encoding for the human VEGF121 cDNA (Ad(CU)VEGF121.1), a control marker gene (Ad beta gal, AdLuc) or no transgene (AdNull) were sutured to fascial edges during laparotomy closure in normal mice and mice treated with dexamethasone. Endpoints addressed included transgene expression in the fascia and surrounding tissue, the number of blood vessels in the healing wound determined using immunostaining, and wound bursting strength using a calibrated tensinometer.

RESULTS

Transgene expression was detected readily in the fascial edges, but only marginally detectable in neighboring tissues. In normal mice and mice treated with dexamethasone, no differences were observed at 7 days. Strikingly, however, 21 days after wound closure/therapy, significantly more blood vessels were present in the wounds that received the VEGF121 vector compared with controls (normal: AdNull: 4.2 +/- 1.8; Ad(CU)VEGF121.1: 11.2 +/- 1.2; P <.05; dexamethasone: AdNull: 1.4 +/- 0.8; Ad(CU)VEGF121.1: 5.4 +/- 1.2; P <.05), and bursting strength was significantly higher in VEGF121-treated wounds (normal: AdNull: 665 +/- 68 mN/mm; Ad(CU)VEGF121.1: 956 +/- 82 mN/mm; P <.0005; dexamethasone: AdNull: 234 +/- 111 mN/mm; Ad(CU)VEGF121.1: 592 +/- 121 mN/mm; P <.03).

CONCLUSIONS

Adenovirus-mediated gene transfer to healing fascial wounds is achieved readily using a microfibrillar collagen sponge, with transfer of the human VEGF121 cDNA significantly enhancing wound vascularity and bursting strength in normal mice, as well as in mice treated with dexamethasone.

In vitro effect of transforming growth factor-beta on adhesion molecule expression by human gingival fibroblasts cultured in the presence of a titanium abutment

BACKGROUND

There is little information in the literature on the structural basis mediating gingival cell adhesion to the surface of titanium abutments. We cultured gingival fibroblasts on a titanium abutment creating as closely as possible the in vivo state. We analyzed the constitutive and transforming growth factor (TGF) beta-induced expression of the adhesion molecules CD44, CD49b, CD49c, CD51, CD54, and CD61 and extracellular matrix (ECM) components fibronectin, laminin and collagen IV.

METHODS

Three totally edentulous patients underwent implant treatment to anchor the mandibular denture on 2 implants. Gingival mucosa cell specimens were collected from the mandible during the first surgical stage and the gingival fibroblast cultures were prepared. Cells were cultured for 48 hours with or without isoforms TGF-beta1, TGF-beta2, and TGF-beta3. The expression of adhesion molecules and ECM components was analyzed by immunofluorescence staining and flow cytometry.

RESULTS

The addition of TGF-beta isoforms to the cell culture over the incubation period had little effect on cell growth rate, but significantly influenced cell orientation, which changed from a sun-burst pattern in control conditions to a more elongated organization and perpendicular to abutment surface. In all fibroblast preparations, a marked expression of CD44 and a moderate positivity for anti-CD49b and CD49c were found. By contrast, CD51, CD54, and CD61 expressions were negligible. When fibroblasts were cultured for 48 hours in the presence of TGF-beta, the expression of most of the receptor molecules increased. The cells expressed constitutively moderate levels of laminin and fibronectin and low amounts of collagen IV. By contrast, treatment with any one of the 3 TGF-beta isoforms greatly enhanced the expression levels of fibronectin, laminin, and, especially, collagen IV.

CONCLUSIONS

TGF-beta not only seems to affect the orientation of the cultured gingival fibroblasts, but also to induce a clear-cut modification of their adhesion molecule expression.

The mast cell in wound healing

This review describes the role of the mast cell in the pathobiology of skin healing. After illustrating its main morphofunctional characteristics, with special reference to the dog and cat, we consider the involvement of the mast cell in the various phases of skin repair. With the aid of a wide array of newly formed or preformed mediators released by degranulation, the activated mast cell controls the key events of the healing phases: triggering and modulation of the inflammatory stage, proliferation of connective cellular elements and final remodelling of the newly formed connective tissue matrix. The importance of the mast cell in regulating healing processes is also demonstrated by the fact that a surplus or deficit of degranulated biological mediators causes impaired repair, with the formation of exuberant granulation tissue (e.g. keloids and hypertrophic scars), delayed closure (dehiscence) and chronicity of the inflammatory stage.

Postsurgical wound management

Successful outcomes in cutaneous surgery depend on a variety of factors, including preoperative assessment of the patient's health and expectations, intraoperative skill and attention to detail, and managing the postoperative period. Once the procedure is complete, careful selection of dressings, provision of adequate analgesia, judicious management of complications and monitoring the phases of early maturation while providing patient education improve the likelihood of long-term patient and physician satisfaction.

Cutaneous wound healing: an update

Our understanding of wound-healing mechanisms has progressed over the past decade. Wound healing is traditionally divided into three phases--the inflammatory phase, the proliferation phase, and the remodeling phase--and involves a well-orchestrated interaction among blood vessels (platelets, macrophages, neutrophils, endothelial cells, and smooth muscle cells), epidermis (keratinocytes, melanocytes, and Langerhans cells), adnexal structures (outer root sheath cells and hair dermal papilla cells), dermis (fibroblasts and myofibroblasts), nervous system (neurons), and subcutaneous fatty layers (adipocytes). We review recent discoveries of basic and clinical aspects of wound healing including several revolutions that occurred in wound management: occlusive dressing therapy, use of living skin equivalents, and topical administration of growth factors. As we previously proposed, the use of tissue substitutes and autologous epidermal sheets led to a new concept of skin grafting through the keratinocyte activation phase in the graft healing mechanism. In this review, we also discuss a representative patient who presented with plantar wounds caused by calcaneal osteomyelitis and healed by the coverage of epidermal grafting.

p63 expression during normal cutaneous wound healing in humans

p63, a recently identified member of the p53 family, was shown to play a role in morphogenesis and, probably, in tumors of keratinocyte origin. Because p63 seems to be a marker of keratinocytes with a high proliferative potential, the expression of this protein was studied along with another marker of cell proliferation, Ki67, during normal epidermal regeneration in humans. Serial biopsies of human skin healing by a secondary intention were taken at various time intervals (between days 2 and 21 after the injury) and were studied immunohistochemically with the use of a 4A4 monoclonal antibody against the DeltaNp63 variant and MM1 monoclonal antibody against the Ki67 antigen. In the normal and injured skin, the expression of the DeltaNp63 protein was restricted to the epidermal keratinocytes and hair follicle keratinocytes. In the first days of the healing process, there was a dramatic down-regulation of both DeltaNp63 and Ki67 expression in the area of the epidermal tongue invading under the crust. Five days after the injury, induction of DeltaNp63 in the basal keratinocytes could be detected, followed by a gradual increase of its expression in subsequent days. Several days after complete wound closure, DeltaNp63 was still strongly expressed not only in the basal keratinocytes but also in the entire spinous layer, whereas the Ki67 expression was restricted to single cells in the basal layer. The results indicate that DeltaNp63 could be involved in the control of physiologic processes, such as cell proliferation and migration, related to epidermal repair during healing of normal skin in humans.

Function and spatial distribution of ion channels and transporters in cell migration

Cell migration plays a central role in many physiological and pathophysiological processes, such as embryogenesis, immune defense, wound healing, or the formation of tumor metastases. Detailed models have been developed that describe cytoskeletal mechanisms of cell migration. However, evidence is emerging that ion channels and transporters also play an important role in cell migration. The purpose of this review is to examine the function and subcellular distribution of ion channels and transporters in cell migration. Topics covered will be a brief overview of cytoskeletal mechanisms of migration, the role of ion channels and transporters involved in cell migration, and ways by which a polarized distribution of ion channels and transporters can be achieved in migrating cells. Moreover, a model is proposed that combines ion transport with cytoskeletal mechanisms of migration.

Haemophilus ducreyi associates with phagocytes, collagen, and fibrin and remains extracellular throughout infection of human volunteers

In a previous study, Haemophilus ducreyi was found in the pustule and dermis of samples obtained at the clinical end point in the human model of infection. To understand the kinetics of localization, we examined infected sites at 0, 24, and 48 h after inoculation and at the clinical end point. Immediately after inoculation, bacteria were found predominantly in the dermis but also in the epidermis. Few bacteria were detectable at 24 h; however, by 48 h, bacteria were readily seen in the pustule and dermis. H. ducreyi was associated with polymorphonuclear leukocytes and macrophages in the pustule and at its base, but was not associated with T cells, Langerhans' cells, or fibroblasts. H. ducreyi colocalized with collagen and fibrin but not laminin or fibronectin. Association with phagocytes, collagen, and fibrin was seen as early as 48 h and persisted at the pustular stage of disease. Optical sectioning by confocal microscopy and transmission electron microscopy both failed to demonstrate intracellular H. ducreyi. These data identify collagen and fibrin as potentially important targets of adherence in vivo and strongly suggest that H. ducreyi remains extracellular throughout infection and survives by resisting phagocytic killing in vivo.

DsrA-deficient mutant of Haemophilus ducreyi is impaired in its ability to infect human volunteers

Haemophilus ducreyi produces an outer membrane protein called DsrA, which is required for serum resistance. An isogenic dsrA mutant, FX517, was constructed previously in H. ducreyi 35000. Compared to its parent, FX517 cannot survive in normal human serum. When complemented in trans with a plasmid containing dsrA, FX517 is converted to a serum-resistant phenotype (C. Elkins, K. J. Morrow, Jr., and B. Olsen, Infect. Immun. 68:1608-1619, 2000). To test whether dsrA was transcribed in vivo, we successfully amplified transcripts in five biopsies obtained from four experimentally infected human subjects. To test whether DsrA was required for virulence, six volunteers were experimentally infected with 35000 and FX517 and observed for papule and pustule formation. Each subject was inoculated with two doses (70 to 80 CFU) of live 35000 and 1 dose of heat-killed bacteria on one arm and with three doses (ranging from 35 to 800 CFU) of live FX517 on the other arm. Papules developed at similar rates at sites inoculated with the mutant or parent. However, mutant papule surface areas were significantly smaller than parent papules. The pustule formation rate was 58% (95% confidence interval [CI] of 28 to 85%) at 12 parent sites, and 0% (95% CI of 0 to 15%) at 18 mutant sites (P = 0.0004). Although biosafety regulations precluded our testing the complemented mutant in humans, these results suggest that expression of DsrA facilitates the ability of H. ducreyi to progress to the pustular stage of disease.

Laser treatment of hypertrophic scars, keloids, and striae

The successful use of the 585-nm pulsed dye laser for the treatment of hypertrophic scars has been well established over the past decade. Although 5 years ago this treatment option might have been considered as a viable choice only after all other methods failed, it is now generally recognized as an excellent first-line treatment option. Early scar treatment with pulsed dye laser irradiation effectively prevents scar formation or worsening and yields a better and more prolonged clinical improvement. The concomitant use of corticosteroids, 5-fluorouracil, or other treatments is proving to be of particular importance in reducing scar bulk and symptoms of more proliferative scars. Although optimal management for keloids and striae has yet to be determined, pulsed dye laser irradiation will no doubt continue to play a role in their treatment.

Transplantation of virally transduced cells into the dermis of immunocompetent and immunodeficient (SCID) mice to determine gene expression profile and differential donor cell survival

Cell therapy and bioengineering hold great promise as therapeutic approaches using cells and cell-derived factors to treat various pathologic or trauma-induced states. One possible application is the transplantation of cells into wounded tissue to help regulate tissue repair. Cells engineered for optimal wound healing may help to minimize scarring following surgery or to enhance the rate of healing of chronic wounds. The purpose of the current study was to determine the effect of a viral insert, the LacZ-bearing, first generation adenovirus AdRGD, on the survival of dermally transplanted murine skin allogenic fibroblasts. The LacZ insert facilitated quantitation of both cell survival and gene expression and was used here to measure viable cell number. In addition to bearing the LacZ marker, the AdRGD vector is capable of carrying therapeutic gene inserts, so this study tested the feasibility of gene therapy for wound healing. Murine skeletal muscle PP6 (i.e., Pre-Plate 6) myogenic stem cells served as an alternate donor cell type. Cells were labeled with the LacZ-bearing AdRGD adenovirus vector and injected (50,000 cells/site) into the dorsal skin of adult normal, immunocompetent mice as well as in immunodeficient SCID mice. Skin biopsies were taken on days 0, 1, 2, 3, and 7 post-transplant, and assayed for LacZ expression. Soon after transplant (day 1), cell numbers underwent a transient decrease, but by day 2 post-transplant they were present in appreciable numbers. Between days 2-7 post-transplant, both allogenic fibroblasts and PP6 myogenic stem cells maintained survivability in similar numbers. Further, survival of transplanted cell types was similar in both normal, immunocompetent as well as SCID mice during this time period. There were no signs of acute inflammation or rejection in any of the samples. This study shows that AdRGD-transduced cells are not immunogenic in the mouse skin model and the cells show similar survival for the first 7 days post-transplantation independent of the cell type or immunocompetence of the host.

The macrophage in acute neural injury: changes in cell numbers over time and levels of cytokine production in mammalian central and peripheral nervous systems

We evaluated the timing and density of ED-1-positive macrophage accumulation (ED 1 is the primary antibody for the macrophage) and measured cytokine production by macrophages in standardized compression injuries to the spinal cord and sciatic nerves of individual rats 3, 5, 10 and 21 days post-injury. The actual site of mechanical damage to the nervous tissue, and a more distant site where Wallerian degeneration had occurred, were evaluated in both the peripheral nervous system (PNS) and the central nervous system (CNS) at these time points. The initial accumulation of activated macrophages was similar at both the central and peripheral sites of damage. Subsequently, macrophage densities at all locations studied were statistically significantly higher in the spinal cord than in the sciatic nerve at every time point but one. The peak concentrations of three cytokines, tumor necrosis factor α (TNF α), interleukin-1 (IL-1) and interleukin-6 (IL-6), appeared earlier and were statistically significantly higher in injured spinal cord than in injured sciatic nerve. We discuss the meaning of these data relative to the known differences in the reparative responses of the PNS and CNS to injury.

Second intention healing after Mohs micrographic surgery

BACKGROUND

Although second intention healing has been used for many years in Mohs micrographic surgery, it has lost popularity. This is due to the long process and functional alteration of important anatomical units if certain wound healing factors are not carefully taken into consideration.

OBJECTIVE

To review indications, contraindications, complications, advantages, disadvantages, as well as basic concepts of the wound healing process, wound care and antibiotic prophylaxis in the management of open wounds after Mohs surgery.

METHODS

A short but comprehensive review of studies published in the literature dealing with second intention healing as a reconstruction alternative option in certain situations.

CONCLUSIONS

Second intention healing is a simple and cost-effective method for reconstruction after Mohs micrographic surgery in well-defined cases. It allows adequate tumoral control with good to excellent functional and cosmetic results.

Involvement of keratinocyte activation phase in cutaneous graft healing: comparison of full-thickness and split-thickness skin grafts

BACKGROUND

Little is known about keratinocytic activation in the graft take and healing process.

OBJECTIVE

To investigate the clinical and molecular differences between pure epidermal sheet graft (PESG), split-thickness skin graft (STSG), and full-thickness skin graft (FTSG).

METHODS

Three different thickness skin grafts (PESG, STSG, and FTSG) were performed onto three kinds of porcine wounds: shallow, deep, and full. Graft take, contraction, and Ki-67 and beta1 integrin expression in epidermis were studied.

RESULTS

All grafts took well. As expected, full wounds covered by PESG and STSG contracted more than those covered by FTSG, whereas shallow wounds covered by FTSG contracted more than those covered by STSG. No difference in contracture was observed among deep wounds covered by PESG, STSG, and FTSG. Up-regulation of Ki-67 and beta1 integrin expression was greater in PESG and STSG, compared with little expression in FTSG.

CONCLUSION

The keratinocytic activation phase may occur both in the STSG and PESG healing process, as well as serum imbibition, inosculatory, and revascularization phases.