F. Frank Isik

Wnt signaling induces epithelial differentiation during cutaneous wound healing

BackgroundCutaneous wound repair in adult mammals does not regenerate the original epithelial architecture and results in altered skin function. We propose that lack of regeneration may be due to the absence of appropriate molecular signals to promote regeneration. In this study, we investigated the regulation of Wnt signaling during cutaneous wound healing and the consequence of activating either the beta-catenin-dependent or beta-catenin-independent Wnt signaling on epidermal architecture during wound repair.ResultsWe determined that the expression of Wnt ligands that typically signal via the beta-catenin-independent pathway is up-regulated in the wound while the beta-catenin-dependent Wnt signaling is activated in the hair follicles adjacent to the wound edge. Ectopic activation of beta-catenin-dependent Wnt signaling with lithium chloride in the wound resulted in epithelial cysts and occasional rudimentary hair follicle structures within the epidermis. In contrast, forced expression of Wnt-5a in the deeper wound induced changes in the interfollicular epithelium mimicking regeneration, including formation of epithelia-lined cysts in the wound dermis, rudimentary hair follicles and sebaceous glands, without formation of tumors.ConclusionThese findings suggest that adult interfollicular epithelium is capable of responding to Wnt morphogenic signals necessary for restoring epithelial tissue patterning in the skin during wound repair.

True incidence of all complications following immediate and delayed breast reconstruction.

Background: Improved self-image and psychological well-being after breast reconstruction are well documented. To determine methods that optimized results with minimal morbidity, the authors examined their results and complications based on reconstruction method and timing. Methods: The authors reviewed all breast reconstructions after mastectomy for breast cancer performed under the supervision of a single surgeon over a 6-year period at a tertiary referral center. Reconstruction method and timing, patient characteristics, and complication rates were reviewed. Results: Reconstruction was performed on 240 consecutive women (94 bilateral and 146 unilateral; 334 total reconstructions). Reconstruction timing was evenly split between immediate (n = 167) and delayed (n = 167). Autologous tissue (n = 192) was more common than tissue expander/implant reconstruction (n = 142), and the free deep inferior epigastric perforator was the most common free flap (n = 124). The authors found no difference in the complication incidence with autologous reconstruction, whether performed immediately or delayed. However, there was a significantly higher complication rate following immediate placement of a tissue expander when compared with delayed reconstruction (p = 0.008). Capsular contracture was a significantly more common late complication following immediate (40.4 percent) versus delayed (17.0 percent) reconstruction (p < 0.001; odds ratio, 5.2; 95 percent confidence interval, 2.3 to 11.6). Conclusions: Autologous reconstruction can be performed immediately or delayed, with optimal aesthetic outcome and low flap loss risk. However, the overall complication and capsular contracture incidence following immediate tissue expander/implant reconstruction was much higher than when performed delayed. Thus, tissue expander placement at the time of mastectomy may not necessarily save the patient an extra operation and may compromise the final aesthetic outcome.

Mesenchymal stem cells induce dermal fibroblast responses to injury.

Although bone marrow-derived mesenchymal stem cells have been shown to promote repair when applied to cutaneous wounds, the mechanism for this response remains to be determined. The aim of this study was to determine the effects of paracrine signaling from mesenchymal stem cells on dermal fibroblast responses to injury including proliferation, migration and expression of genes important in wound repair. Dermal fibroblasts were co-cultured with bone marrow-derived mesenchymal stem cells grown in inserts, which allowed for paracrine interactions without direct cell contact. In this co-culture model, bone marrow-derived mesenchymal stem cells regulate dermal fibroblast proliferation, migration and gene expression. When co-cultured with mesenchymal stem cells, dermal fibroblasts show increased proliferation and accelerated migration in a scratch assay. A chemotaxis assay also demonstrated that dermal fibroblasts migrate towards bone marrow-derived mesenchymal stem cells. A PCR array was used to analyze the effect of mesenchymal stem cells on dermal fibroblast gene expression. In response to mesenchymal stem cells, dermal fibroblasts up-regulate integrin alpha 7 expression and down-regulate expression of ICAM1, VCAM1 and MMP11. These observations suggest that mesenchymal stem cells may provide an important early signal for dermal fibroblast responses to cutaneous injury.

Results of 268 pressure sores in 158 patients managed jointly by plastic surgery and rehabilitation medicine.

&NA; Despite improvements in surgical repair of pressure sores, recurrence rates greater than 80 percent are reported, thus indicating that this difficult problem is not yet solved. Recurrence results in additional hospitalizations and increased medical expenses. Because associated general clinical and social issues are numerous for these patients, our physical medicine and rehabilitation colleagues are active participants in their perioperative medical care. In addition, the Department of Physical Medicine and Rehabilitation also directs a complete postreconstruction rehabilitation and education program for them. The results of surgically repaired pressure sores for patients managed in this collaborative fashion have not been previously reported. Pressure sore patients at the Harborview and University of Washington Medical Centers are evaluated by plastic surgery colleagues together with the Department of Physical Medicine and Rehabilitation. Patients believed to be candidates for complete postoperative rehabilitation are offered surgical repair and constitute this study cohort. Individuals who cannot cooperate with our protocol are treated nonoperatively and are not included in this study. A retrospective analysis of all 158 patients (mean age 34.5 years) operated on for 268 grade III and IV pressure sores between October of 1977 and December of 1989 was performed. Following surgical debridement and reconstruction, patients receive their principal medical care from the Department of Physical Medicine and Rehabilitation service while the Plastic Surgery Department manages the surgical wounds. Graduated patient mobilization is initiated in accord with a mutually agreed upon standardized protocol. New or primary sores numbered 174 (65 percent), and recurrent or secondary sores numbered 94 (35 percent). Mean patient follow‐up was 3.7 years. The overall pressure sore recurrence rate (recurrence at the same site) was 19 percent, and the overall patient recurrence rate (previous patient developing a new sore) was 25 percent. Recurrence rates of 22 and 15 percent were noted for primary and secondary pressure sores, respectively. On most recent examination, 131 patients (83 percent) had intact pelvic and perineal skin. These results support a collaborative approach to the management of high‐grade pressure sore patients. Our protocol of mutual patient evaluation followed by surgical reconstruction and postoperative rehabilitation yields notably low recurrence rates of both primary and secondary sores. In addition, the high percentage of patients who manifest long‐term maintenance of skin integrity demonstrates the excellent education in personal skin and selfcare that this approach provides. Not only do patients enjoy successful and durable reconstructive results, but additional hospitalizations and health care expenses implicit to pressure sore recurrence are consequently diminished. This collaborative clinical effort remains our standard of care. (Plast. Reconstr. Surg. 102: 765, 1998.)

Review of the female Duroc/Yorkshire pig model of human fibroproliferative scarring

Hypertrophic scarring after burns is an unsolved problem and remains as devastating today as it was in the 40s and it may be that the main reason for this is the lack of an accepted, useful animal model. The female, red Duroc pig was described as a model of hypertrophic scarring nearly 30 years ago but then vanished from the literature. This seemed strange since the authors reported that 12 of 12 pigs developed thick scar. In the mid 90s we explored the model and found that, indeed, the red Duroc pig does make thick scar. Other authors have established that the Yorkshire pig does not heal in this fashion so there is the possibility of a same species control. We have continued to explore the Duroc/Yorkshire model and herein describe our experiences. Is it a perfect model of hypertrophic scarring? No. Is it a useful model of hypertrophic scarring? Time will tell. We have now obtained gene expression data from the Duroc/Yorkshire model and analysis is underway.

Analysis of hypertrophic and normal scar gene expression with cDNA microarrays.

Hypertrophic scar is one form of abnormal wound healing. Previous studies have suggested that hypertrophic scar formation results from altered gene expression of extracellular matrix molecules. A broadscale evaluation of gene expression in hypertrophic scars has not been reported. To better understand abnormalities in hypertrophic scar gene expression, we compared messenger RNA expression in hypertrophic scars, normal scars, and uninjured skin with the use of complementary (c)DNA microarrays. Total RNA was extracted from freshly excised human hypertrophic scars, normal scars, or uninjured skin and reverse transcribed into cDNA with the incorporation of [33P] deoxycytidine triphosphate. The resulting radioactive cDNA probes were hybridized onto cDNA microarrays of 4000 genes. Hybridization signals were normalized and analyzed. In the comparison of tissue samples, mean intensities were calculated for each gene within each group (hypertrophic scars, normal scars, and uninjured skin). Ratios of the mean intensities of hypertrophic scars to normal scars, hypertrophic scars to uninjured skin, and normal scars to uninjured skin were generated. A ratio that was greater than 1 indicated upregulation of any particular gene and a ratio that was less than 1 indicated downregulation of any particular gene. Our data indicated that 142 genes were overexpressed and 50 genes were underexpressed in normal scars compared with uninjured skin, 107 genes were overexpressed and 71 were underexpressed in hypertrophic scars compared with uninjured skin, and 44 genes were overexpressed and 124 were underexpressed in hypertrophic scars compared with normal scars. Our analysis of collagen, growth factor, and metalloproteinase gene expression confirmed that our molecular data were consistent with published biochemical and clinical observations of normal scars and hypertrophic scars. cDNA microarray analysis provides a powerful tool for the investigation of differential gene expression in hypertrophic scar samples and either uninjured skin or normal scars. Our data validate the use of this technology for future studies on gene expression during repair processes of normal and abnormal wounds.

Human dermal microvascular endothelial cells produce nerve growth factor : implications for wound repair

Following cutaneous injury, sensory nerves regenerate into the dermis and epidermis. Tissues that are innervated by sensory nerves synthesize neurotrophins such as nerve growth factor (NGF). The close anatomic proximity of nerves and capillaries throughout the skin suggests that mutual regulation may exist between nerve fibers and microvascular endothelial cells (MECs) during wound repair. Release of the neuropeptide substance P by sensory nerves induces endothelial cell rounding, capillary leak, and cytokine upregulation. We propose that dermal endothelial cells produce neurotrophins required for nerve fiber maintenance and regeneration. In this study, we demonstrate that substance P stimulates NGF messenger RNA expression by cultured human dermal MECs. Likewise, enzyme-linked immunosorbant assay demonstrated that conditioned medium from cultured dermal MECs contains NGF. NGF bioactivity in the supernates was verified by conditioned medium-induced clonal rat pheochromocytoma (PC-12) cell differentiation. This activity was inhibited by anti-NGF antibodies. Therefore, we have demonstrated that substance P, an inflammatory neuropeptide released by sensory nerve fibers, induces endothelial cells to produce NGF. Our data suggest that MECs may be unrecognized contributors to nerve regeneration after cutaneous injury.

Simplifying the vertical reduction mammaplasty.

The vertical reduction mammaplasty is an evolving technique. Its proponents report significantly decreased scarring, better breast shape, and more stable results compared with the standard inverted-T method, but the learning curve is long and cosmetic outcomes can be inconsistent. Many surgeons have experimented with the vertical closure before returning to methods more familiar to them. The authors present their modifications to the vertical reduction mammaplasty. Their changes simplify the preoperative markings and the intraoperative technique to shorten the learning curve while maintaining reliable aesthetic results. With the patient standing, only four preoperative marks are made: (1) the inframammary fold; (2) the breast axis; (3) the apex of the new nipple-areola complex; and (4) the medial and lateral limbs of the vertical incision. In the operating room, a medial or a superomedial pedicle is developed. Excess breast skin is resected with the inferior and lateral parenchyma as a C-shaped wedge. The lateral skin-adipose flap is redraped inferomedially and sutured to the chest wall. The inferior aspect of the breast is aggressively debulked and a gathering subcuticular stitch is started 2 cm below the nadir of the nipple-areola complex. Finally, a 38-mm to 42-mm nipple-areola complex marker is used to create a circular defect that is offset 0.5 cm medial to the vertical axis of the breast. In their series, 56 patients were treated and no major complications were noted. The median follow-up period was 17 months. The average reduction was 554.5 g per breast; however, the reduction was greater than 1000 g per breast in eight patients. The authors found that (1) chest wall anchoring improves lateral contour and minimizes axillary fullness; (2) aggressive debulking inferiorly avoids the persistent inferior bulge; and (3) starting the subcuticular gathering suture 2 cm below the nipple-areola complex followed by placement of a nipple-areola complex marker at the conclusion of the case prevents lateral deviation and corrects the nipple-areola complex teardrop deformity. These innovations accelerate the learning curve by simplifying the preoperative markings and lead to more consistent postoperative results and an improved cosmetic outcome. In conclusion, these modifications yield a simple, easily learned vertical reduction mammaplasty with aesthetically reliable results.

Pressure sores in the acute trauma patient : Incidence and causes

OBJECTIVES The purpose of this review was to determine the incidence of pressure sores in acute trauma patients and to identify the causes. DESIGN AND MATERIALS AND METHODS: This study is a retrospective chart review of all acute trauma patients admitted to Harborview Medical Center between January of 1991 and December of 1993 who were discharged with an ICD-9 diagnosis of acute pressure sore. RESULTS A total of 7,492 trauma patients were admitted. Thirty-two patients developed 44 pressure sores for an incidence of 0.4%. All of the patients were severely injured (mean Injury Severity Score, 21). Eighteen (41%) of the pressure sores developed as a result of unrelieved positional pressure. Thirteen (30%) of the pressure sores were equipment induced. CONCLUSION Our incidence of pressure sores in acute trauma victims is very low and occurs in those most seriously injured. The majority of the wounds are due to unrelieved pressure from body positioning or equipment failure.

SUBSTANCE P ENHANCES WOUND CLOSURE IN NITRIC OXIDE SYNTHASE KNOCKOUT MICE

INTRODUCTION The neuropeptide, substance P (SP), up-regulates nitric oxide production (NO). The purpose of this study was to determine whether SP enhances response to cutaneous injury in nitric oxide synthase knockout (NOS null) mice. METHODS We studied mice with targeted deletions of the 3 NOS genes, neuronal NOS, inducible NOS, or endothelial NOS. Full thickness dorsal wounds were treated daily (d 0-6) with topical SP or normal saline (NaCl). Wounds were analyzed by flow cytometry for macrophage, leukocyte, endothelial, and dendritic cells. Healing time and wound epithelialization were compared using analysis of variance. RESULTS Wound closure in the 3 NOS null mice was slower than the control mice (P < 0.05). SP treatment enhanced wound closure in NOS null mice (P < 0.02). NOS null wounds exhibited reduced inflammation. SP increased macrophage, leukocyte, and dendritic cell densities at d 3 and d 7 (P < 0.05) in all NOS null mice. SP increased endothelial cell number in neuronal NOS and inducible NOS null mice, but not in endothelial NOS null mice (P > 0.05). CONCLUSIONS SP ameliorated the impaired wound healing response observed in NOS null mice by enhancing wound closure kinetics and epithelialization. SP increased inflammatory cell density in the wounds supporting the essential role of inflammatory cells, especially macrophages, in wound repair.