Effects of a topical enamel matrix derivative on skin wound healing

Histological Evaluation of Pulpal Response and Dentin Bridge Formation After Direct Pulp Capping Using Recombinant Amelogenin and Mineral Trioxide Aggregate (MTA)

The purpose of the study was to compare and histologically investigate pulpal response and dentin bridge formation after direct pulp capping using recombinant amelogenin and mineral trioxide aggregate (MTA). Recombinant amelogenin protein and MTA were used as pulp capping materials in 120 teeth from eight mongrel dogs. Dogs were sacrificed at two different evaluation times. Regenerative changes were evaluated histologically. At two weeks, in contrast to the MTA group, most of the amelogenin group showed moderately formed hard tissue formation and the pulp tissue was completely filling the entire pulp chamber. These results were statistically significant. At two months, all the samples of the amelogenin group showed complete dentin bridge formation and the pulp chamber was filled entirely with tissue-mimicking the authentic pulp in all the specimens of the amelogenin group. These results were statistically significant. In conclusion, direct pulp capping by recombinant amelogenin protein resulted in significantly better regeneration of the dentin-pulp complex than MTA.

Low-vacuum negative pressure wound therapy protocol for complex wounds with exposed vessels

OBJECTIVE

Treating high-risk surgical patients with complex wounds over exposed blood vessels is a challenge. Guided wound healing may be the only treatment possible. Negative pressure wound therapy (NPWT) is not recommended in these cases. The authors challenged these current recommendations and share their preliminary experience.

METHOD

The authors adapted a NPWT protocol that uses low-vacuum continuous pressure (-80mmHg) with a silicone sheath and gauze/foam dressing between the wound bed and the device. They monitored the clinical features of patients' wounds to detect bleeding/ischaemia early on. Dressings were changed every 72-96 hours.

RESULTS

This protocol was followed in five male patients (aged 23-68 years) with complex wounds over exposed vessels. Two cases were foot crush injuries, one midfoot amputation, one hand self-subamputation and one vascular bypass infection. Comorbidities included monoarterial limbs/stump, severe arteriopathy and psychiatric disorder. The exposed vessels were femoral, radial and ulnar, anterior and posterior tibial arteries and veins. Mean treatment lasted 37 days (range 20-61 days). No episodes of severe bleeding/ischaemia of the extremities were observed. Treatment was discontinued once debridement was complete and granulation tissue allowed spontaneous closure/grafting. All wounds appeared stable at 1-year follow-up.

CONCLUSION

The low-vacuum NPWT protocol was successful in solving five difficult cases. This regimen reduces risks associated with NPWT use on wounds with exposed vessels. The authors believe further validation is required to strengthen the evidence. However, preliminary data are encouraging and might help to change future NPWT recommendations by extending the indications for its use to exposed vessels.

Practical Things You Should Know about Wound Healing and Vacuum-Assisted Closure Management

LEARNING OBJECTIVES

After reading this article, the participant should be able to: 1. Understand the basics of negative-pressure wound therapy and practical uses of various vacuum-assisted closure dressings. 2. Understand the mechanisms of action of negative-pressure therapies and other important adjuncts, such as perfusion imaging. 3. Discuss the evidence for hyperbaric oxygen therapy in wound care.

SUMMARY

Wound healing requires creating an environment that supports the healing process while decreasing inflammation and infection. Negative-pressure wound therapy has changed the way physicians manage acute and chronic wounds for more than 20 years. It contracts wound edges, removes exudate, including inflammatory and infectious material, and promotes angiogenesis and granulation tissue formation. These effects have been consistently demonstrated in multiple animal and human randomized controlled trials. Recent innovations that include instillation therapy and closed incision have further increased our arsenal against difficult-to-treat wounds and incisions at high risk of complications. Instillation of topical wound solutions allows physicians to cleanse the wound without return to the operating room, resulting in fewer debridements, shorter hospital stays, and faster time to wound closure. Other concepts have yielded negative-pressure therapy on top of closed surgical incisions, which holds incision edges together, reduces edema, promotes angiogenesis, and creates a barrier to protect incisions during the critical healing period, thereby reducing surgical-site complications, especially infection. Other practical adjuncts to the modern-day treatment of acute and chronic wounds include indocyanine green angiography, which allows real-time assessment of perfusion, and hyperbaric oxygen treatment, which has been suggested to augment healing in acute, chronic, specifically diabetic foot ulcers and radiation-related wounds.

Potential usefulness of enamel matrix derivative in skin and mucosal injury treatment

Enamel matrix proteins (EMP) are secreted by ameloblasts during odontogenesis. The main component of enamel protein extract is amelogenin. The extracts also contain proteins with bioactive properties similar to bone morphogenic proteins and transforming growth factor β1. Research on animal models indicates that EMP improve healing of oral mucosa wounds by stimulating the production of collagen fibers and blood vessels in the connective tissue. Success in the treatment of oral wounds prompted interest in possible applications of amelogenins in the repair of damaged skin due to similarities in histological structure between skin and mucosa.

Biomimetic Biomolecules in Next Generation Xeno-Hybrid Bone Graft Material Show Enhanced In Vitro Bone Cells Response

Bone defects resulting from trauma, disease, surgery or congenital malformations are a significant health problem worldwide. Consequently, bone is the second most transplanted tissue just after blood. Although bone grafts (BGs) have been used for decades to improve bone repairs, none of the currently available BGs possesses all the desirable characteristics. One way to overcome such limitations is to introduce the feature of controlled release of active bone-promoting biomolecules: however, the administration of, e.g., recombinant Bone morphogenetic proteins (BMPs) have been used in concentrations overshooting physiologically occurring concentrations and has thus raised concerns as documented side effects were recorded. Secondly, most such biomolecules are very sensitive to organic solvents and this hinders their use. Here, we present a novel xeno-hybrid bone graft, SmartBonePep^®, with a new type of biomolecule (i.e., intrinsically disordered proteins, IDPs) that is both resistant to processing with organic solvent and both triggers bone cells proliferation and differentiation. SmartBonePep^® is an advanced and improved modification of SmartBone^®, which is a bone substitute produced by combining naturally-derived mineral bone structures with resorbable polymers and collagen fragments. Not only have we demonstrated that Intrinsically Disordered Proteins (IDPs) can be successfully and safely loaded onto a SmartBonePep^®, withstanding the hefty manufacturing processes, but also made them bioavailable in a tuneable manner and proved that these biomolecules are a robust and resilient biomolecule family, being a better candidate with respect to other biomolecules for effectively producing the next generation bone grafts. Most other biomolecules which enhances bone formation, e.g., BMP, would not have tolerated the organic solvent used to produce SmartBonePep^®.

Effects of enamel matrix proteins on adherence, proliferation and migration of epithelial cells: A real-time in vitro study

Enamel matrix derivative (EMD) can mimic odontogenic effects by inducing the proliferation and differentiation of connective tissue progenitor cells, stimulating bone growth and arresting epithelial cells migration. To the best of our knowledge, there is no data indicating that any active component of EMD reduces epithelial cell viability. The present study examines the impact of commercial lyophilized EMD, porcine recombinant amelogenin (prAMEL; 21.3 kDa) and tyrosine-rich amelogenin peptide (TRAP) on the adherence, proliferation and migration of human epithelial cells in real-time. The tongue carcinoma cell line SCC-25 was stimulated with EMD, porcine recombinant AMEL and TRAP, at concentrations of 12.5, 25 and 50 µg/ml. Cell adherence, migration and proliferation were monitored in real-time using the xCELLigence system. No significant effects of EMD on the morphology, adhesion, proliferation and migration of SCC-25 cells were observed. However, porcine recombinant AMEL had a dose-dependent inhibitory effect on SCC-25 cell proliferation and migration. Predominantly, no notable differences were found between control and TRAP-treated cells in terms of cell adhesion and migration, a decrease in proliferation was observed, but this was not statistically significant. EMD and its active components do not increase the tongue cancer cell viability.

Influence of Enamel Matrix Derivative on Human Epithelial Cells In Vitro

BACKGROUND

In periodontal therapy enamel matrix derivative (EMD) has been successfully used for tissue regeneration by altering activity of various cells involved in periodontal regeneration. Studies have focused primarily on clinical parameters and outcome. Effects of EMD on oral epithelial cells are of crucial importance in order to understand the biology of regeneration. Aims of this study are to investigate proliferative and cytotoxic effects of EMD on oral epithelial cells and their possible influences on epithelial barrier function.

METHODS

SCC-25 cells, a human squamous cell carcinoma cell line, and primary keratinocytes were either treated with EMD dissolved in culture medium or added to wells/inserts precoated with EMD. Cells were incubated for 24, 48, and 72 hours. Proliferation rate was analyzed measuring the 5-bromo-2'-deoxyuridine nucleotide uptake. Cytotoxic effects of EMD treatment were sampled by lactate dehydrogenase release. Alterations of the epithelial barrier function induced by EMD were investigated by analysis of transepithelial electrical resistance (TER).

RESULTS

Statistically significant inhibitory effects of both malignant and primary cell proliferation could be demonstrated by precoating culture plate wells with EMD. No cytotoxic effects caused by EMD were detected. Precoating of inserts with EMD induced a significant increase of TER and barrier function.

CONCLUSIONS

This investigation compares applying EMD in solution to cells with precoating of wells with EMD. When precoating of wells was used solely, inhibition of cell proliferation was evident. Precoating may represent more suitable clinical usage. Furthermore, prelayering EMD induced an increase of TER of primary cells. These results suggest EMD may enhance barrier function.

Enamel Matrix Derivative Promotes Healing of a Surgical Wound in the Rat Oral Mucosa

BACKGROUND

Enamel matrix proteins (EMPs) play a role in enamel formation and the development of the periodontium. Sporadic clinical observations of periodontal regeneration treatments with enamel matrix derivative (EMD), a commercial formulation of EMPs, suggest that it also promotes post-surgical healing of soft tissues. In vitro studies showed that EMD stimulates various cellular effects, which could potentially enhance wound healing. This study examines the in vivo effects of EMD on healing of an oral mucosa surgical wound in rats.

METHODS

A bilateral oral mucosa wound was created via a crestal incision in the anterior edentulous maxilla of Sprague-Dawley rats. Full-thickness flaps were raised, and, after suturing, EMD was injected underneath the soft tissues on one side, whereas the EMD vehicle was injected in the contralateral side. Animals were sacrificed after 5 or 9 days, and the wound area was subjected to histologic and immunohistochemical analysis of the epithelial gap, number of macrophages, blood vessels, proliferating cells, and collagen content in the connective tissue (CT). Gene expression analysis was also conducted 2 days post-surgery.

RESULTS

EMD had no effect on the epithelial gap of the wound. On both days 5 and 9, EMD treatment increased significantly the number of blood vessels and the collagen content. EMD also enhanced (by 20% to 40%) the expression of transforming growth factors β1 and β2, vascular endothelial growth factor, interleukin-1β, matrix metalloproteinase-1, versican, and fibronectin.

CONCLUSION

EMD improves oral mucosa incisional wound healing by promoting formation of blood vessels and collagen fibers in CT.

Proline-Rich Peptide Mimics Effects of Enamel Matrix Derivative on Rat Oral Mucosa Incisional Wound Healing

BACKGROUND

Proline-rich peptides have been shown to promote periodontal regeneration. However, their effect on soft tissue wound healing has not yet been investigated. The aim of this study is to evaluate the effect of enamel matrix derivative (EMD), tyrosine-rich amelogenin peptide (TRAP), and a synthetic proline-rich peptide (P2) on acute wound healing after a full-thickness flap procedure in an incisional rat model.

METHODS

This experimental study has a split-mouth, randomized, placebo-controlled design. Test and control wounds were created on the palatal mucosa of 54 Sprague-Dawley rats. Wounds were histologically processed, and reepithelialization, leukocyte infiltration, and angiogenesis were assessed at days 1, 3, and 7 post-surgery.

RESULTS

EMD and P2 significantly promoted early wound closure at day 1 (P <0.001 and P = 0.004, respectively). EMD maintained a significant acceleration of reepithelialization at day 3 (P = 0.004). Wounds treated by EMD and P2 showed increased angiogenesis during the first 3 days of healing (P = 0.03 and 0.001, respectively). Leukocyte infiltration was decreased in EMD-treated wounds at day 1 (P = 0.03), and P2 and TRAP induced a similar effect at days 3 (P = 0.002 and P <0.0001, respectively) and 7 (P = 0.005 and P <0.001).

CONCLUSION

EMD and P2 promoted reepithelialization and neovascularization in full-thickness surgical wounds on rat oral mucosa.

The Use of Biologic Scaffolds in the Treatment of Chronic Nonhealing Wounds

Significance: Injuries to the skin as a result of illness or injury, particularly chronic nonhealing wounds, present a major healthcare problem. Traditional wound care approaches attempt to control the underlying causes, such as infection and ischemia, while the application of wound dressings aims to modify a poorly healing wound environment into a microenvironment more closely resembling an acute wound allowing the body to heal the wound naturally. Recent Advances: Regenerative medicine approaches, such as the use of biologic scaffold materials comprising an intact extracellular matrix (ECM) or individual components of the ECM, are providing new therapeutic options that focus upon the provision of biochemical cues that alter the wound microenvironment to facilitate rapid restoration of normal skin architecture. Critical Issues: The incidence of chronic nonhealing wounds continues to increase. For example, between 15% and 20% of diabetics are likely to develop chronic, nonhealing foot wounds creating an increasing burden on healthcare systems worldwide. Future Directions: Developing a thorough understanding of wound microenvironment and the mechanisms by which biologic scaffolds work in vivo has the potential to markedly improve outcomes in the clinical translation for the treatment of chronic wounds.

Enamel matrix proteins exhibit growth factor activity: A review of evidence at the cellular and molecular levels

Enamel matrix derivative (EMD) is a commercially available protein extract, mainly comprising amelogenins. A number of other polypeptides have been identified in EMD, mostly growth factors, which promote cementogenesis and osteogenesis during the regeneration processes through the regulation of cell proliferation, differentiation and activity; however, not all of their functions are clear. Enamel extracts have been proposed to have numerous activities such as bone morphogenetic protein- and transforming growth factor β (TGF-β)-like activity, and activities similar to those of insulin-like growth factor, fibroblast growth factor, platelet-derived growth factor, vascular endothelial growth factor and epidermal growth factor. These activities have been observed at the molecular and cellular levels and in numerous animal models. Furthermore, it has been suggested that EMD contains an unidentified biologically active factor that acts in combination with TGF-β1, and several studies have reported functional similarities between growth factors and TGF-β in cellular processes. The effects of enamel extracts on the cell cycle and biology are summarized and discussed in this review.

Emdogain-regulated gene expression in palatal fibroblasts requires TGF-βRI kinase signaling

Genome-wide microarrays have suggested that Emdogain regulates TGF-β target genes in gingival and palatal fibroblasts. However, definitive support for this contention and the extent to which TGF-β signaling contributes to the effects of Emdogain has remained elusive. We therefore studied the role of the TGF-β receptor I (TGF-βRI) kinase to mediate the effect of Emdogain on palatal fibroblasts. Palatal fibroblasts were exposed to Emdogain with and without the inhibitor for TGF-βRI kinase, SB431542. Emdogain caused 39 coding genes to be differentially expressed in palatal fibroblasts by microarray analysis (p<0.05; >10-fold). Importantly, in the presence of the TGF-βRI kinase inhibitor SB431542, Emdogain failed to cause any significant changes in gene expression. Consistent with this mechanism, three independent TGF-βRI kinase inhibitors and a TGF-β neutralizing antibody abrogated the increased expression of IL-11, a selected Emdogain target gene. The MAPK inhibitors SB203580 and U0126 lowered the impact of Emdogain on IL-11 expression. The data support that TGF-βRI kinase activity is necessary to mediate the effects of Emdogain on gene expression in vitro.

Negative Pressure Wound Therapy With Instillation (NPWTi) Better Reduces Post-debridement Bioburden in Chronically Infected Lower Extremity Wounds Than NPWT Alone

OBJECTIVE

An overabundance of bacteria in the chronic wound plays a significant role in the decreased ability for primary closure. One means of decreasing the bioburden in a wound is to operatively debride the wound for wound bed optimization prior to application of other therapy, such as Negative Pressure Wound Therapy (NPWT). We undertook a prospective pilot study to assess the efficacy of wound bed preparation for a standard algorithm (sharp surgical debridement followed by NPWT) versus one employing sharp surgical debridement followed by Negative Pressure Wound Therapy with Instillation (NPWTi).

METHODS

Thirteen patients, corresponding to 16 chronic lower leg and foot wounds were taken to the operating room for debridement. The patients were sequentially enrolled in 2 treatment groups: the first receiving treatment with operative debridement followed by 1 week of NPWT with the instillation of quarter strength bleach solution; the other receiving a standard algorithm consisting of operative debridement and 1 week of NPWT. Quantitative cultures were taken pre-operatively after sterile preparation and draping of the wound site (POD # 0, pre-op), post-operatively once debridement was completed (POD # 0, post-op), and on post-operative day 7 after operative debridement (POD # 7, post-op).

RESULTS

After operative debridement (post-operative day 0) there was a mean of 3 (±1) types of bacteria per wound. The mean CFU/gram tissue culture was statistically greater - 3.7 × 10(6) (±4 × 10(6)) in the NPWTi group, while in the standard group (NPWT) the mean was 1.8 × 10(6) (±2.36 × 10(6)) CFU/gram tissue culture (p = 0.016); at the end of therapy there was no statistical difference between the two groups (p = 0.44). Wounds treated with NPWTi had a mean of 2.6 × 10(5) (±3 × 10(5)) CFU/gram of tissue culture while wounds treated with NPWT had a mean of 2.79 × 10(6) (±3.18 × 10(6)) CFU/gram of tissue culture (p = 0.43). The mean absolute reduction in bacteria for the NPWTi group was 10.6 × 10(6) bacteria per gram of tissue while there was a mean absolute increase in bacteria for the NPWT group of 28.7 × 10(6) bacteria per gram of tissue, therefore there was a statistically significant reduction in the absolute bioburden in those wounds treated with NPWTi (p = 0.016).

CONCLUSION

It has long been realized that NPWT does not make its greatest impact by bioburden reduction. Other work has demonstrated that debridement alone does not reduce wound bioburden by more than 1 Log. Wounds treated with NPWTi (in this case with quarter strength bleach instillation solution) had a statistically significant reduction in bioburden, while wounds treated with NPWT had an increase in bioburden over the 7 days.

Chronic wounds - is cellular 'reception' at fault? Examining integrins and intracellular signalling

As with all physiologic processes, chronic wounds are associated with unique intracellular and cellular/extracellular matrix (ECM) receptor types and signalling messages. These cellular receptors mediate responses of the epidermis to provisional wound matrix and change in form and number in cases of impaired wound healing. Integrins are the major cell-surface receptors for cell adhesion and migration and epidermal keratinocytes express several integrins that bind ECM ligands in provisional wound ECM. Integrin receptors and more particularly integrin clusters and focal adhesion points appear to influence epidermal and dermal cell matrix interactions, cell motility, cell phenotype and ultimate healing trajectory. In chronic wounds, a variety of changes in receptors have been identified: decreased integrin α5β1 receptors affect the integration of fibronectin and subsequent keratinocyte migration; integrin αvβ6 stimulate transforming growth factor (TGF)-β and may increase the susceptibility to ulceration and fibrosis; however, TGF-β signal receptors have been found to be dysfunctional in many chronic wounds; additionally receptor interactions result in increased senescent cells including fibroblasts, myofibroblasts and even keratinocytes - this produces a degradative ECM and wound bed and corrosive chronic wound fluid. The activation or inhibition of integrin receptors by various agents may provide an excellent means of influencing wound healing. This process offers an earlier intervention into the wound healing cascade promoting intrinsic healing and elaboration of growth factors and ECM proteins, which may be more cost effective than the traditional attempts at extrinsic addition of these agents.

One-step purification of recombinant human amelogenin and use of amelogenin as a fusion partner

Amelogenin is an extracellular protein first identified as a matrix component important for formation of dental enamel during tooth development. Lately, amelogenin has also been found to have positive effects on clinical important areas, such as treatment of periodontal defects, wound healing, and bone regeneration. Here we present a simple method for purification of recombinant human amelogenin expressed in Escherichia coli, based on the solubility properties of amelogenin. The method combines cell lysis with recovery/purification of the protein and generates a >95% pure amelogenin in one step using intact harvested cells as starting material. By using amelogenin as a fusion partner we could further demonstrate that the same method also be can explored to purify other target proteins/peptides in an effective manner. For instance, a fusion between the clinically used protein PTH (parathyroid hormone) and amelogenin was successfully expressed and purified, and the amelogenin part could be removed from PTH by using a site-specific protease.

Effect of enamel matrix derivative protein on the healing of standardized epithelial wounds: a histomorphometric analysis in vivo

The enamel matrix derivative (EMD) is a preparation of the enamel matrix proteins secreted by the Hertwig's epithelial root sheath. It has been shown that EMD promotes periodontal wound healing; however, the significance of the protein in repairing skin wounds is insufficiently addressed. The aim of this in vivo histomorphometric investigation was to analyse the effect of EMD protein on the healing of standardised epithelial wounds. Dorsal skin of 22-week-old female guinea pigs (n = 33) was scarified and divided into test- (topical application of EMD) and control-sites (sutured and allowed to heal). Animals were euthanised at specific time intervals and the specimens were then evaluated histomorphometrically. The mean widths of the external wound gaps (WGs) in the test- and control-sites at the 5th, 20th and 35th day of healing were 5·89, 3·6 and 1·01 mm and 6·41, 5·02 and 3·43 mm, respectively. Histomorphometric analysis showed a statistically significant difference in the WGs between the test- and control-sites. A significant increase in the formation of organised connective tissue matrix, collagen fibres and early muscle formation was observed in the test-sites as compared with the control-sites. Within the limits of this study, it is concluded that topical application of the EMD on standardised epithelial allows early wound closure and promotes healing as compared to when the defects are merely sutured.

Enamel matrix protein derivatives: role in periodontal regeneration

The role of regenerative periodontal therapy is the reconstitution of lost periodontal structures, ie, new formation of root cementum, periodontal ligament, and alveolar bone. The outcome of basic research has pointed to the important role of enamel matrix protein derivative (EMD) in periodontal wound healing. Histologic results from animal and human studies have shown that treatment with EMD promotes periodontal regeneration. Moreover, clinical studies have indicated that treatment with EMD positively influences periodontal wound healing in humans. The goal of this paper is to review the existing literature on EMD.

A clinical review of infected wound treatment with Vacuum Assisted Closure (V.A.C.) therapy: experience and case series

Over the last decade Vacuum Assisted Closure((R)) (KCI Licensing, Inc., San Antonio, TX) has been established as an effective wound care modality for managing complex acute and chronic wounds. The therapy has been widely adopted by many institutions to treat a variety of wound types. Increasingly, the therapy is being used to manage infected and critically colonized, difficult-to-treat wounds. This growing interest coupled with practitioner uncertainty in using the therapy in the presence of infection prompted the convening of an interprofessional expert advisory panel to determine appropriate use of the different modalities of negative pressure wound therapy (NPWT) as delivered by V.A.C.((R)) Therapy and V.A.C. Instill((R)) with either GranuFoam() or GranuFoam Silver() Dressings. The panel reviewed infected wound treatment methods within the context of evidence-based medicine coupled with experiential insight using V.A.C.((R)) Therapy Systems to manage a variety of infected wounds. The primary objectives of the panel were 1) to exchange state-of-practice evidence, 2) to review and evaluate the strength of existing data, and 3) to develop practice recommendations based on published evidence and clinical experience regarding use of the V.A.C.((R)) Therapy Systems in infected wounds. These recommendations are meant to identify which infected wounds will benefit from the most appropriate V.A.C.((R)) Therapy System modality and provide an infected wound treatment algorithm that may lead to a better understanding of optimal treatment strategies.

Anti-inflammatory effects of EMD in the presence of biomechanical loading and interleukin-1β in vitro

Enamel matrix derivative (EMD) used to promote periodontal regeneration has been shown to exert anti-inflammatory effects. This in vitro study was performed to investigate if the anti-inflammatory actions of EMD are modulated by the local cellular environment, such as inflammation or occlusal, i.e., biomechanical, loading. Human periodontal ligament cells were seeded on BioFlex plates and incubated with EMD under normal, inflammatory, and biomechanical loading conditions for 1 and 6 days. In order to mimic inflammatory and biomechanical loading conditions in vitro, cells were stimulated with interleukin (IL)-1β and exposed to dynamic tensile strain, respectively. The gene expression of IL-1β, IL-1 receptor antagonist (IL-1RN), IL-6, IL-8, IL-10, and cyclooxygenase (COX)-2 was analyzed by real-time RT-PCR and the IL-6 protein synthesis by enzyme-linked immunoassay. For statistical analysis, Student's t test, ANOVA, and post-hoc comparison tests were applied (p < 0.05). EMD downregulated significantly the expression of IL-1β and COX-2 at 1 day and of IL-6, IL-8, and COX-2 at 6 days in normal condition. In an inflammatory environment, the anti-inflammatory actions of EMD were significantly enhanced at 6 days. In the presence of low biomechanical loading, EMD caused a downregulation of IL-1β and IL-8, whereas high biomechanical loading significantly abrogated the anti-inflammatory effects of EMD at both days. Neither IL-1RN nor IL-10 was upregulated by EMD. These data suggest that high occlusal forces may abrogate anti-inflammatory effects of EMD and should, therefore, be avoided immediately after the application of EMD to achieve best healing results.

Anastomotic leakage after esophageal resection: new treatment options by endoluminal vacuum therapy

BACKGROUND

Anastomotic leakage after esophagectomy is an important determinant of early and late morbidity and mortality. Control of the septic focus is essential when treating patients with anastomotic leakages. Surgical and endoscopic treatment options are limited.

METHODS

Between 2005 and 2009, we treated 6 patients who experienced an intrathoracic anastomotic leakage after esophageal resection. After all established therapeutic measures had failed, we explored the feasibility of an endoscopically assisted mediastinal vacuum therapy.

RESULTS

We were able to heal intrathoracic esophageal leakages in all 6 patients without any local complications and without the need for reoperation. One patient died because of a progressive pneumonia.

CONCLUSIONS

Endoscopic vacuum-assisted closure of anastomotic leakages may help to overcome the limitations that are associated with intermittent endoscopic treatment and conventional drainage therapy. Our preliminary results suggest that this new concept may be suitable for those patients.

Effects of enamel matrix derivative on vascular endothelial growth factor expression and microvessel density in gingival tissues of periodontal pocket: a comparative study

BACKGROUND

Vascular endothelial growth factor (VEGF) stimulates proliferation and migration of endothelial cells, and correlates with inflammatory resolution and periodontal tissue healing. Enamel matrix derivative (EMD) seems to stimulate soft tissue healing. Our aim was to assess if topical EMD application in an instrumented periodontal pocket could affect angiogenesis at the gingival level.

METHODS

A total of 56 periodontal sites in 28 patients were treated with a single session of comprehensive scaling and root planing under local anesthesia after recording the clinical attachment level (CAL). EMD gel in the test site or only the vehicle propylene glycol alginate in aqueous solution in the control site of the same mouth was applied onto the root surfaces and into the pocket and left in place for 3 minutes. After 48 hours, gingival biopsies were collected for histologic and immunohistochemical analysis for VEGF and CD34 (for microvessel density [MVD] count) antibodies. Statistical comparisons were performed by analysis of variance test.

RESULTS

Endothelial VEGF expression and MVD were statistically different in the test site compared to the control site. VEGF expression and MVD of the control site were not correlated with CAL, whereas the test site showed high correlations among CAL and endothelial VEGF or MVD.

CONCLUSIONS

EMD induces proliferation and viability and angiogenesis of human microvascular cells. Recent clinical and histologic studies found EMD to be useful as an adjunct to scaling and root planing in single-rooted teeth. Our findings may help to understand the mechanisms involved in soft tissue healing, through the ability of EMD to increase angiogenesis at periodontal pockets.

Osteogenesis in an in vitro coculture of human periodontal ligament fibroblasts and human microvascular endothelial cells

BACKGROUND

Periodontal bone healing is a complex process involving many cells and processes that must function flawlessly for proper healing to occur. The exact progenitor cells that contribute to this process are not fully characterized. Periodontal fibroblasts and pericytes were postulated to be potential osteoprogenitor cells. This study describes a viable coculture model for the in vitro study of osteogenesis.

METHODS

Human microvascular endothelial cells (HMVEC) and human periodontal ligament (HPDL) fibroblasts were cocultured in a layered model and monitored for the development of runt-related transcription factor 2 (runx2) and desmin expression by real-time polymerase chain reaction. Conditions shown to be osteogenic (bone morphogenetic protein [BMP]-2 and enamel matrix derivative [EMD]) were compared to a control coculture that was unstimulated.

RESULTS

The HMVEC migrated into a layer of collagen containing only HPDL cells as monitored by fluorescent labeling. runx2 and desmin expressions were increased in stimulated cocultures in week 2 compared to controls. At week 3, the unstimulated control cocultures developed the expression of runx2 and desmin, and the cocultures that were stimulated with EMD and BMP-2 achieved significantly higher levels of these factors than any of the other conditions.

CONCLUSIONS

Signs of osteogenesis were present in the cocultures in unstimulated and stimulated conditions. However, in the stimulated condition, osteogenic markers were increased at earlier time points. As such, this model may provide a good method for the study of specific cellular processes that may lead to osteogenesis and eventually for understanding the regeneration of periodontal bone in vivo.

Versatile use of vacuum-assisted healing in fifty patients

Context:

Wound management can often be a challenging experience, especially in the presence of diabetes mellitus, vascular or immunological compromise. While no single technique can be considered by itself to be ideal, vacuum-assisted healing, which is a recent innovation, is fast becoming a necessary addition as adjuvant therapy to hasten wound healing.

Aims:

To determine the efficacy of vacuum-assisted healing.

Settings and Design:

Plastic surgery centre. Ministry of Health Hospital, Kuwait.

Materials and Methods:

Patients from Kuwait in a wide variety of clinical situations were chosen for study: Patients (n=50) were classified by diagnosis: Group 1: pressure sore- sacral (n= 3), trochanteric (n=6), ischial (n= 2); Group 2: ulcers (n= 11); Group 3: traumatic soft tissue wounds (n =15); Group 4: extensive tissue loss from the abdominal wall perineum, thigh and axilla (n =5); Group 5: sternal dehiscence wounds (n =4) and Group 6: wounds from flap necrosis (n =4). All wounds were subjected to vacuum by wall unit or portable unit, using pressure of 100-125 mm - continuous or intermittent. Closure of wounds, significant reduction in size and refusal by patient for continuation of vacuum-assisted closure therapy were end points of vacuum application.

Results:

Sixteen per cent of patients showed complete healing of the wound. Seventy per cent of patients showed 20-78% reduction in wound size. In 14% of patients treatment had to be discontinued. All patients showed improvement in granulation tissue and reduction in bacterial isolates and tissue oedema.

Conclusions:

The application of subatmospheric pressure or negative pressure promotes healing in a wide range of clinical settings and is an advanced wound healing therapy that can optimize patient care, promote rapid wound healing and help manage costs. It may be used in most instances in both hospital and community settings.

Effects of enamel matrix derivative on proliferation/viability, migration, and expression of angiogenic factor and adhesion molecules in endothelial cells in vitro

BACKGROUND

The aim of this study was to test in vitro the effect of enamel matrix derivative (EMD) on the proliferation/viability, migration, and expression of angiogenic factor and adhesion molecules in human umbilical vein endothelial cells (HUVECs). To date, discussions on angiogenic effects of EMD are rather controversial.

METHODS

The effect of EMD on the proliferation/viability of HUVECs after 24 hours was measured using 3,4,5-dimethylthiazol-2-yl-2,5-diphenyl tetrazolium bromide (MTT) assay and direct cell counting. Cell migration was observed in an especially adapted in vitro monolayer wound-healing model. The expression of angiogenic factor angiopoietin-2 (ang-2) and adhesion molecules intercellular adhesion molecule (ICAM)-1 and vascular endothelium-selectin (E-selectin) was quantified with real-time polymerase chain reaction (PCR).

RESULTS

The proliferation/viability of HUVECs measured in MTT assay was stimulated by 0.1 microg/ml EMD and inhibited by higher doses (50 to 100 microg/ml), but the total number of cells was not affected. Cell migration in the wound-healing assay was promoted by EMD at doses of 0.1 to 50 microg/ml and inhibited at 100 microg/ml. The highest expression level of all three tested genes (ICAM-1, E-selectin, and ang-2) was observed at 50 microg/ml EMD.

CONCLUSION

The results of the present in vitro study show the potential influence of EMD on the angiogenic activity of HUVECs, which may play an important role in periodontal tissue regeneration and wound healing.

Enamel matrix proteins; old molecules for new applications

Emdogain (enamel matrix derivative, EMD) is well recognized in periodontology, where it is used as a local adjunct to periodontal surgery to stimulate regeneration of periodontal tissues lost to periodontal disease. The biological effect of EMD is through stimulation of local growth factor secretion and cytokine expression in the treated tissues, inducing a regenerative process that mimics odontogenesis. The major (>95%) component of EMD is Amelogenins (Amel). No other active components have so far been isolated from EMD, and several studies have shown that purified amelogenins can induce the same effect as the complete EMD. Amelogenins comprise a family of highly conserved extracellular matrix proteins derived from one gene. Amelogenin structure and function is evolutionary well conserved, suggesting a profound role in biomineralization and hard tissue formation. A special feature of amelogenins is that under physiological conditions the proteins self-assembles into nanospheres that constitute an extracellular matrix. In the body, this matrix is slowly digested by specific extracellular proteolytic enzymes (matrix metalloproteinase) in a controlled process, releasing bioactive peptides to the surrounding tissues for weeks after application. Based on clinical and experimental observations in periodontology indicating that amelogenins can have a significant positive influence on wound healing, bone formation and root resorption, several new applications for amelogenins have been suggested. New experiments now confirm that amelogenins have potential for being used also in the fields of endodontics, bone regeneration, implantology, traumatology, and wound care.

A new method for inducing bone tissue regeneration: negative pressure membrane technology

With the advances of medical molecular biology in recent years, our understanding of the process of fracture healing has deepened and the development of new technologies for guided bone regeneration has emerged. Here, with the recent discoveries of membrane-based as well as negative pressure-induced tissue regeneration, we suggest an innovative method of bone regeneration using negative pressure membrane technology. Polymeric membrane materials are implanted around the fracture site using in vitro devices. The container of the membrane between the fracture ends can induce effective negative pressure in order to attain both membrane and negative pressure-induced bone regeneration. The key to this technology is the use of semi-permeable membranes, which prevent the collapse of membranous structures and the loss of a variety of bone marrow cells and larger proteins during the induction of negative pressure.

Cellular effects of enamel matrix derivative are associated with different molecular weight fractions following separation by size-exclusion chromatography

BACKGROUND

Enamel matrix derivative (EMD) was shown to enhance soft tissue healing and regeneration of the periodontium; however, the mechanisms of this action are unknown. It is assumed that amelogenin, the most abundant protein in EMD, is the protein primarily responsible for the effects of EMD. The purpose of this study was to fractionate EMD and associate its specific cellular effects with different molecular weight fractions following size-exclusion chromatography.

METHODS

Freshly dissolved EMD was fractionated by gel filtration, and forty-five 7-ml fractions were collected, desalted, lyophilized, and resuspended. These fractions were analyzed for their effects on the differentiation of osteoprogenitor cells (C2C12) and the proliferation and differentiation of human microvascular endothelial cells (HMVECs). Alkaline phosphatase activity (C2C12) was measured as a marker for osteogenic differentiation before and after preincubation of the fractions with the bone morphogenetic protein (BMP) decoy receptor, noggin. Angiogenesis (HMVEC) was evaluated as a marker for endothelial cell differentiation. Enzymographic assays used polyacrylamide gels copolymerized with denatured type I collagen to determine gelatinolytic activities in each fraction.

RESULTS

EMD fractionated into three major protein peaks following size exclusion chromatography with cross-linked dextran particle matrix. Peak I was associated with the column void volume, whereas peak III eluted near the salt volume. Peak II eluted between these two peaks. Proliferation and angiogenic activities were associated with peaks II and III for the microvascular cells. The differentiation of osteoprogenitor cells, indicated by alkaline phosphatase activity, was induced by EMD components present in peak I and the leading edge of peak II. The additional observation that this differentiation was inhibited by prior treatment of the fractions with noggin suggested the activity was induced by BMP rather than amelogenin or other unknown proteins. Gelatinolytic activities were detected in the early fractions of peaks I and II of gel-fractionated EMD.

CONCLUSIONS

The cellular activities stimulated by EMD are not associated with a single molecular weight species. The fact that noggin abolishes C2C12 alkaline phosphatase activity suggests that effects on osteoprogenitor cell differentiation are the result of a BMP-like protein(s), whereas effects on proliferation and angiogenesis are associated with lower molecular weight species present in peaks II and III. Finally, unheated EMD displays gelatinolytic activities that are also detectable following size-exclusion separation of its constituents. The masses of these activities were consistent with those reported for latent and active matrix metalloproteinase-20.

Topical negative pressure effects on coronary blood flow in a sternal wound model

Several studies have suggested that mediastinitis is a strong predictor for poor long-term survival after coronary artery bypass surgery (CABG). In those studies, several conventional wound-healing techniques were used. Previously, we have shown no difference in long-term survival between CABG patients with topical negative pressure (TNP)-treated mediastinitis and CABG patients without mediastinitis. The present study was designed to elucidate if TNP, applied over the myocardium, resulted in an increase of the total amount of coronary blood flow. Six pigs underwent median sternotomy. The coronary blood flow was measured, before and after the application of TNP (-50 mmHg), using coronary electromagnetic flow meter probes. Analyses were performed before left anterior descending artery (LAD) occlusion (normal myocardium) and after 20 minutes of LAD occlusion (ischaemic myocardium). Normal myocardium: 171.3 +/- 14.5 ml/minute before to 206.3 +/- 17.6 ml/minute after TNP application, P < 0.05. Ischaemic myocardium: 133.7 +/- 18.4 ml/minute before to 183.2 +/- 18.9 ml/minute after TNP application, P < 0.05. TNP of -50 mmHg applied over the LAD region induced a significant increase in the total coronary blood flow in both normal and ischaemic myocardium.

Amelogenin, an extracellular matrix protein, in the treatment of venous leg ulcers and other hard-to-heal wounds: experimental and clinical evidence

Amelogenins are extracellular matrix proteins that, under physiological conditions, self-assemble into globular aggregates up to micron-sizes. Studies with periodontal fibroblasts indicate that attachment to these structures increases the endogenous secretion of multiple growth factors and cell proliferation. Pre-clinical and clinical studies indicate that cutaneous wounds benefit from treatment with amelogenins. A randomized controlled trial (RCT) involving patients with hard-to-heal venous leg ulcers (VLUs) (ie, ulcers with a surface area ≥10 cm² and duration of ≥6 months) showed that the application of amelogenin (Xelma^®, Molnlycke Health Care, Gothenburg, Sweden) as an adjunct treatment to compression results in significant reduction in ulcer size, improvement in the state of ulcers, reduced pain, and a larger proportion of ulcers with low levels of exudate, compared with treatment with compression alone. Amelogenin therapy was also shown to be safe to use in that there were no significant differences in adverse events noted between patients treated with amelogenin plus compression and those treated with compression alone. Case study evaluations indicate that the benefits of amelogenin therapy demonstrated in the RCT are being repeated in “real life” situations and that amelogenin therapy may also have a role to play in the treatment of other wound types such as diabetic foot ulcers.

Negative pressure wound therapy with instillation: a pilot study describing a new method for treating infected wounds

This data review reports the results of 15 patients who were treated with Vacuum-Assisted Closure (VAC) negative pressure therapy system in addition to the timed, intermittent delivery of an instilled topical solution for management of their complex, infected wounds. Prospective data for 15 patients treated with negative pressure wound therapy (NPWT)-instillation was recorded and analysed. Primary endpoints were compared to a retrospective control group of 15 patients treated with our institution's standard moist wound-care therapy. Culture-specific systemic antibiotics were prescribed as per specific patient need in both groups. All data were checked for normality of distribution and equality of variance and appropriate parametric and non parametric analyses were conducted. Compared with the standard moist wound-care therapy control group, patients in the NPWT-instillation group required fewer days of treatment (36.5 +/- 13.1 versus 9.9 +/- 4.3 days, P < 0.001), cleared of clinical infection earlier (25.9 +/- 6.6 versus 6.0 +/- 1.5 days, P < 0.001), had wounds close earlier (29.6 +/- 6.5 versus 13.2 +/- 6.8 days, P < 0.001) and had fewer in-hospital stay days (39.2 +/- 12.1 versus 14.7 +/- 9.2 days, P < 0.001). In this pilot study, NPWT instillation showed a significant decrease in the mean time to bioburden reduction, wound closure and hospital discharge compared with traditional wet-to-moist wound care. Outcomes from this study analysis suggest that the use of NPWT instillation may reduce cost and decrease inpatient care requirements for these complex, infected wounds.

The Effect of Negative Pressure Therapy on the Femoral Vein Blood Flow and Wall Structure

Negative pressure therapy has been recently used for managing lymphatic or infective groin complications. The aim of this study was to investigate any possible association between application of negative pressure therapy in the groin area and deep-vein thrombosis. Acute surgical wounds were created at the inguinal areas in 7 pigs. Different negative pressures ranging from −50 to −200 mmHg were applied directly over the femoral vessels, and blood flow alterations were studied using a Doppler ultrasound. Femoral vein specimens were also removed for histological examination after 12 hours of therapy. It has been demonstrated that negative pressure therapy does not significantly alter the baseline lower limb venous return. Histology demonstrated several changes, which are associated with vein thrombogenesis. The hemodynamic and pathological findings still leave a potential for thrombogenic effects of negative pressure therapy and warrant care to protect the femoral veins, with the use of thrombosis prophylaxis measures.

Mechanisms governing the effects of vacuum-assisted closure in cardiac surgery

SUMMARY

: Vacuum-assisted closure has been adopted as the first-line treatment for poststernotomy mediastinitis as a result of the excellent clinical outcome achieved with its use. Scientific evidence regarding the mechanisms by which vacuum-assisted closure promotes wound healing has started to emerge, although knowledge regarding the effects on heart and lung function is still limited. The organs in the mediastinum are hemodynamically crucial, and in patients with poststernotomy mediastinitis, vulnerable bypass grafts and reduced cardiac function must be taken into consideration during vacuum-assisted closure therapy. This article provides an overview of the effects of vacuum-assisted closure on heart and lung function and summarizes the current knowledge on the mechanisms by which vacuum-assisted closure therapy promotes wound healing.

Enamel matrix proteins bind to wound matrix proteins and regulate their cell-adhesive properties

Enamel matrix proteins (EMP) induce periodontal regeneration and accelerate dermal wound healing, but the cellular mechanisms of these processes are unclear. We investigated the binding of EMP to the wound matrix proteins fibronectin, laminin-1, collagen type I, and collagen type IV and analyzed the interaction of epithelial cells and periodontal ligament fibroblasts (PDLF) with EMP and composite matrices of EMP + fibronectin or EMP + collagen. The adhesion of PDLF to EMP was concentration- and integrin-dependent and did not require de novo protein synthesis. EMP supported PDLF migration. In contrast, keratinocytes did not adhere to EMP if their protein synthesis was blocked. EMP showed concentration-dependent binding of fibronectin, peaking at 100 microg ml(-1) (before the precipitation point) of EMP. Type I collagen binding to EMP peaked at a low (1 microg ml(-1)) and narrow concentration range. Neither laminin-1 nor type IV collagen bound to EMP. Collagen and fibronectin, bound to EMP, showed significantly reduced (> 50%) binding of both epithelial cells and PDLF compared with the equivalent concentration of these proteins alone. PDLF, but not epithelial cell, adhesion was rescued by increasing the EMP concentration. These findings show that EMP binds to wound extracellular matrix proteins and regulates their adhesive properties. Such interactions may favor fibroblast adhesion over epithelial cells, potentially promoting connective tissue regeneration.

Blood Flow Changes in Normal and Ischemic Myocardium During Topically Applied Negative Pressure

BACKGROUND

Topical negative pressure (TNP) therapy has been adopted as a first-line treatment for wound healing. One of the mechanisms by which TNP improves healing is by stimulating blood flow to the wound edge. Among patients with ischemic heart disease, it is of great importance to improve the microvascular blood flow in the myocardium during episodes of ischemia to protect the myocardium from infarction. The present study was designed to elucidate the effect of TNP on microvascular blood flow in the myocardium.

METHODS

Six pigs underwent median sternotomy. The microvascular blood flow in the myocardium was recorded, before and after the application of TNP, by using laser Doppler velocimetry. Analyses were performed before left anterior descending artery (LAD) occlusion (normal myocardium), after 20 minutes of LAD occlusion (ischemic myocardium), and after 20 minutes of reperfusion (reperfused myocardium).

RESULTS

TNP at -0 mm Hg increased microvascular blood flow in the normal myocardium from 14.7 +/- 3.9 perfusion units (PU) before to 25.8 +/- 6.1 PU after TNP application (p < 0.05), in the ischemic myocardium from 7.2 +/- 1.5 PU before to 13.8 +/- 2.6 PU after TNP application (p < 0.05), and in the reperfused myocardium from 10.8 +/- 2.0 PU before to 19.3 +/- 5.6 PU after TNP application (p < 0.05).

CONCLUSIONS

TNP increases the microvascular blood flow significantly in normal, ischemic, and reperfused myocardium and may provide a novel therapeutic tool in the treatment of ischemic myocardium.

V.A.C. Therapy Normalizes Vascular Response of Injured Tissue in Full-Thickness Wounds in Rabbits

V.A.C. Therapy applied to a cutaneous wound was hypothesized to alter vascular regulation in underlying tissue. Two full-thickness wounds were created on the dorsum of 7 New Zealand albino rabbits. One site was treated with V.A.C. Therapy; the other, with saline-moistened gauze. Local perfusion levels in the muscle were measured using laser Doppler flowmetry. Using vena caval occlusion, blood pressure was decreased progressively from baseline under vasonormal conditions and during systemic infusion of a vasodilator and a vasoconstrictor. The pressure-flow relationships for the carotid and V.A.C. Therapy-treated wound sites showed 3 distinct curves, with vasodilator curves shifted upwards and vasoconstrictor curves downwards relative to vasonormal curves (P < 0.05). By contrast, vasodilator curves in the saline-gauze treated sites were indistinguishable from vasonormal curves. Thus, in a rabbit model, application of V.A.C. Therapy to cutaneous wounds normalized the vascular response to vasoactive drugs in a manner similar to undisturbed carotid circulation.

In vitro effects of enamel matrix derivative on microvascular cells

BACKGROUND

Periodontal regeneration requires a coordinated series of events that includes not only the recruitment of periodontal ligament (PDL)-specific cells, but vascular cells as well. The mechanisms of action of enamel matrix derivative (EMD) are poorly understood, and its effects on vascular cells are unknown. The objective of this study was to examine the extent to which EMD affects angiogenesis and PDL cell recruitment.

METHODS

The effects of EMD on human microvascular endothelial cells (HMVECs) were determined by examining proliferation, chemotaxis, angiogenesis, and migration. Proliferation was determined using water-soluble tetrazolium salt (WST)-1 reagent. Chemotaxis was determined using microporous-culture well inserts. Angiogenesis was assessed on plates containing matrigel. The effects of HMVECs on the migration of PDL cells were assessed by evaluating PDL cell outgrowth from collagen gels cultured in the presence of HMVECs on fibrin matrix and surrounded by fibronectin-containing fibrin clots at 24 hours. Effects of EMD on PDL expression of vascular endothelial cell (VEGF) types (A, B, C, and D) and isoforms were determined using reverse transcription-polymerase chain reaction (RT-PCR). Production of VEGF, platelet-derived growth factor (PDGF)-AA, PDGF-BB, PDGF-AB, and transforming growth factor (TGF)-beta1 by EMD-stimulated PDL cells was assessed quantitatively in conditioned media using specific enzyme-linked immunosorbent assays (ELISAs).

RESULTS

EMD at concentrations <50 microg/ml resulted in significant (P <0.05) stimulation of HMVEC proliferation. Compared to baseline, EMD also stimulated a 100% increase in HMVEC chemotaxis when PDL cells were present (P <0.05). All doses of EMD tested (25, 50, and 100 microg/ml) increased angiogenesis in vitro. HMVECs, in combination with EMD at a concentration of 100 microg/ml, stimulated a 750% increase in migration of PDL cells from collagen gels into fibrin clots compared to controls when neither was present. RT-PCR results indicated that PDL cells expressed VEGF-A, -B, and -C and multiple isoforms of VEGF-A, including VEGF(121), VEGF(165), and VEGF(189), whether or not EMD was present in the culture media. ELISAs determined a 400% increase in VEGF concentration by PDL C cells in EMD-stimulated conditioned media and a similar increase in TGF-beta(1)-stimulated media.

CONCLUSIONS

It is likely that EMD stimulates angiogenesis directly by stimulating endothelial cells and indirectly by stimulating the production of angiogenic factors (VEGF) by PDL cells. Importantly, the data are consistent with the concept that EMD enhances bidirectional communication between HMVEC and PDL cells during angiogenesis associated with healing.

A randomized, double-blind, placebo-controlled multicenter trial evaluating topical zinc oxide for acute open wounds following pilonidal disease excision

The purpose of this randomized, double-blind, placebo-controlled multicenter trial was to compare topical zinc oxide with placebo mesh on secondary healing pilonidal wounds. Sixty-four (53 men) consecutive patients, aged 17-60 years, were centrally randomized to either treatment with 3% zinc oxide (n = 33) or placebo (n = 31) by concealed allocation. Patients were followed with strict recording of beneficial and harmful effects including masked assessment of time to complete wound closure. Analysis was carried out on an intention-to-treat basis. Median healing times were 54 days (interquartile range 42-71 days) for the zinc and 62 days (55-82 days) for the placebo group (p = 0.32). Topical zinc oxide increased (p < 0.001) wound fluid zinc levels to 1,540 (1,035-2,265) microM and decreased (p < 0.05) the occurrence of Staphylococcus aureus in wounds. Fewer zinc oxide (n = 3) than placebo-treated patients (n = 12) were prescribed postoperative antibiotics (p = 0.005). Serum-zinc levels increased (p < 0.001) postoperatively in both groups but did not differ significantly between the two groups on day 7. Zinc oxide was not associated with increased pain by the visual analog scale, cellular abnormalities by histopathological examination of wound biopsies, or other harmful effects. Larger clinical trials will be required to show definitive effects of topical zinc oxide on wound healing and infection.

Osteoprotegerin and Receptor Activator of Nuclear Factor-Kappa B Ligand Modulation by Enamel Matrix Derivative in Human Alveolar Osteoblasts

BACKGROUND

Bone regeneration techniques increasingly rely on the use of exogenous molecules able to enhance tissue formation in pathologic and traumatic defects. An enamel matrix derivative (EMD) has been largely used to promote tooth ligament regeneration within periodontal pockets. Recent evidence suggests that EMD may contribute to inducing osteoblast growth and differentiation. We investigated the effects of EMD on growth and osteogenic marker modulation in human mandibular osteoblasts.

METHODS

We focused our attention on cell growth by 3-(4,5-dimethyl[thiazol-2-yl]-3,5-diphery)tetradium bromide (MTT) assay, cell differentiation, mineralized nodule formation, and, in particular, the expression of receptor activator of nuclear factor-kappa B ligand (RANKL), the main osteoclast differentiation factor, and its decoy receptor, osteoprotegerin (OPG), by enzyme-linked immunosorbent assay.

RESULTS

Cell growth was significantly increased by EMD. Similarly, a significantly higher quantity of OPG and a lower amount of RANKL were detectable in groups treated with 50 and 100 microg/ml at weeks 1, 2, and 3, and alkaline phosphatase activity and osteocalcin production were enhanced in cultures treated with 50 and 100 microg/ml at weeks 2 and 3. Mineralized nodules appeared bigger and more numerous in cultures treated with 50 and 100 microg/ml EMD.

CONCLUSIONS

EMD was able to enhance osteoblast cell growth and the expression of markers of osteoblastic phenotype and differentiation. EMD also seemed able to create a favorable osteogenic microenvironment by reducing RANKL release and enhancing osteoblastic OPG production.

Vacuum-Assisted Closure of the Sternotomy Wound: Respiratory Mechanics and Ventilation

BACKGROUND

Numerous authors have reported promising results with the use of vacuum-assisted closure therapy in poststernotomy mediastinitis. The negative pressure applied to the anterior mediastinum substantially exceeds the normal negative pressure in the pleural cavities, and interaction with respiratory physiology cannot be excluded. The aim of the present study was to evaluate whether the application of six clinically relevant negative pressures between -50 mmHg and -175 mmHg to the sternotomy wound affects respiratory parameters in a porcine model.

METHODS

A midline sternotomy was performed in six mechanically ventilated pigs weighing 70 +/- 3 kg. Vacuum-assisted closure therapy was applied with continuous negative pressure in a randomized order to the sternotomy wound. The following respiratory parameters were monitored by a carbon dioxide-based noninvasive monitoring system connected to the ventilator: carbon dioxide elimination, peak inspiratory pressure, peak expiratory flow, alveolar minute volume, alveolar tidal volume, expired tidal volume, static compliance, and airway resistance.

RESULTS

All pigs survived the treatment, and there was no significant change in the respiratory parameters investigated at any of the six negative pressures applied. A tendency toward increased airway resistance was noted when -175 mmHg was applied, although this change was not significant.

CONCLUSIONS

The application of negative pressure therapy in the treatment of deep poststernotomy infections is a novel modality gaining increased attention. In this study, no impairment in respiratory mechanics, ventilation, or oxygenation was detected when comparing applied pressures ranging from -50 mmHg to -175 mmHg in the sternotomy wound.

Topical negative pressure in the treatment of infected wounds with exposed orthopaedic implants

The use of TNP on infected open wounds with exposed orthopaedic implants has not yet been described in the literature. Here, its application on these wounds accelerated healing and enabled definitive wound closure to be undertaken.

Extraperitoneal bladder leakage after provision of topical negative therapy: a case report

Following surgical excision of a prevesical haematoma, topical negative pressure was used to promote wound closure. The development of a vesicocutaneous fistula at the incision site may have been an indirect complication of the therapy.