Protection of stromal cell-derived factor-1 SDF-1/CXCL12 against proteases yields improved skin wound healing.

SDF-1/CXCL12 is a unique chemotactic factor with multiple functions on various types of precursor cells, all carrying the cognate receptor CXCR4. Whereas individual biological functions of SDF-1/CXCL12 have been well documented, practical applications in medicine are insufficiently studied. This is explained by the complex multifunctional biology of SDF-1 with systemic and local effects, critical dependence of SDF-1 activity on aminoterminal proteolytic processing and limited knowledge of applicable modulators of its activity. We here present new insights into modulation of SDF-1 activity in vitro and in vivo by a macromolecular compound, chlorite-oxidized oxyamylose (COAM). COAM prevented the proteolytic inactivation of SDF-1 by two inflammation-associated proteases: matrix metalloproteinase-9/MMP-9 and dipeptidylpeptidase IV/DPPIV/CD26. The inhibition of proteolytic inactivation was functionally measured by receptor-mediated effects, including intracellular calcium mobilization, ERK1/2 phosphorylation, receptor internalization and chemotaxis of CXCR4-positive cells. Protection of SDF-1/CXCL12 against proteolysis was dependent on electrostatic COAM-SDF-1 interactions. By in vivo experiments in mice, we showed that the combination of COAM with SDF-1 delivered through physiological fibrin hydrogel had beneficial effect for the healing of skin wounds. Collectively, we show that COAM protects SDF-1 from proteolytic inactivation, maintaining SDF-1 biological activities. Thus, protection from proteolysis by COAM represents a therapeutic strategy to prolong SDF-1 bioavailability for wound healing applications.

Physiological fibrin hydrogel modulates immune cells and molecules and accelerates mouse skin wound healing.

Introduction: Wound healing is a complex process to restore homeostasis after injury and insufficient skin wound healing is a considerable problem in medicine. Whereas many attempts of regenerative medicine have been made for wound healing with growth factors and cell therapies, simple pharmacological and immunological studies are lagging behind. We investigated how fibrin hydrogels modulate immune cells and molecules in skin wound healing in mice. Methods: Physiological fibrin hydrogels (3.5 mg/mL fibrinogen) were generated, biophysically analyzed for stiffness and protein contents and were structurally studied by scanning electron microscopy. Physiological fibrin hydrogels were applied to full thickness skin wounds and, after 3 days, cells and molecules in wound tissues were analyzed. Leukocytes, endothelial cells, fibroblasts and keratinocytes were explored with the use of Flow Cytometry, whereas cytokines and matrix metalloproteinases were analyzed with the use of qPCR, ELISAs and zymography. Skin wound healing was analyzed microscopically at day 3, macroscopically followed daily during repair in mice and compared with commercially available fibrin sealant Tisseel. Results: Exogenous fibrin at physiological concentrations decreased neutrophil and increased non-classical Ly6Clow monocyte and resolutive macrophage (CD206+ and CX3CR1+) populations, at day 3 after injury. Fibrin hydrogel reduced the expression of pro-inflammatory cytokines and increased IL-10 levels. In line with these findings, gelatinase B/MMP-9 was decreased, whereas gelatinase A/MMP-2 levels remained unaltered. Frequencies of dermal endothelial cells, fibroblasts and keratinocytes were increased and keratinocyte migration was enhanced by fibrin hydrogel. Importantly, physiological fibrin accelerated the healing of skin wounds in contrast to the highly concentrated fibrin sealant Tisseel, which delayed wound repair and possessed a higher fiber density. Conclusion: Collectively, we show that adding a tailored fibrin hydrogel scaffold to a wound bed positively influences the healing process, modulating leukocyte populations and inflammatory responses towards a faster wound repair.

Maxillomandibular Reconstruction Using Insourced Virtual Surgical Planning and Homemade CAD/CAM: A Single-Center Evolution in 75 Patients.

BACKGROUND: Virtual surgical planning (VSP) and computer-aided design and manufacturing (CAD/CAM) of surgical guides and jigs have dramatically changed the predictability of bony reconstruction of the jaw. VSP craftsmanship can lead to precision and enables the surgeon to complement the donor bone osteotomies with bony resection of the jaw. In recent years, immediate dental rehabilitation has become an integral part of VSP. However, outsourced CAD/CAM technology is expensive and may not be an option for many institutions worldwide. METHODS: The authors present here a consecutive series of 75 maxillofacial reconstructions from 2015 to 2020. We established an insourced "in-house" protocol for VSP and "home-made" CAD/CAM for the reconstruction of maxilla-mandibular defects with fibula, iliac crest, and scapular angle flaps. All patient files were analyzed retrospectively, and relevant parameters influencing the reconstructive outcome were determined. RESULTS: The authors went from a fibula-based protocol toward the selection of optimal vascularized bone for immediate placement of osteointegrated implants. Bone flap survival was 94.7% after 4 months. The 3-year patient survival is 77.6%. The authors show the multiple steps required for the routine use of in-house CAD/CAM and report the related financial balance. CONCLUSIONS: Insourced VSP and CAD/CAM has evolved into a valuable strategy in maxillomandibular reconstruction that promotes accuracy and precision and allows for occlusion-based planning with quality-of-life and aesthetic outcomes as essential parts of the reconstruction even in high-level oral cancers. Further reductions in the hardware and software acquisition costs may lead to widespread implementation of this innovative technology. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Chlorite-Oxidized Oxyamylose (COAM) Has Antibacterial Activity and Positively Affects Skin Wound Healing.

Purpose: To verify the antibacterial and immunomodulatory effects of the amylose derivative - chlorite-oxidized oxyamylose (COAM) - in a skin wound setting. Methods: In vitro antibacterial effects of COAM against opportunistic bacterial pathogens common to skin wounds, including Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA), were determined by cultivation methods. The effects of COAM on myeloid cell infiltration into full thickness skin wounds were investigated in wild-type and in transgenic CX3CR1-GFP mice. Results: On the basis of in vitro experiments, an antibacterial effect of COAM against Staphylococcus species including MRSA was confirmed. The minimum inhibitory concentration of COAM was determined as 2000 µg/mL against these bacterial strains. Control full thickness skin wounds yielded maximal neutrophil influxes and no additive effect on neutrophil influx was observed following topical COAM-treatment. However, COAM administration increased local CX3CR1 macrophage counts at days 3 and 4 and induced a trend towards better wound healing. Conclusion: Aside from its known broad antiviral impact, COAM possesses in vitro antibacterial effects specifically against Gram-positive opportunistic pathogens of the skin and modulates in vivo macrophage contents in mouse skin wounds.

Anti-fibrotic effect of adipose-derived stem cells on fibrotic scars.

BACKGROUND: Sustained injury, through radiotherapy, burns or surgical trauma, can result in fibrosis, displaying an excessive deposition of extracellular matrix (ECM), persisting inflammatory reaction, and reduced vascularization. The increasing recognition of fibrosis as a cause for disease and mortality, and increasing use of radiotherapy causing fibrosis, stresses the importance of a decent anti-fibrotic treatment. AIM: To obtain an in-depth understanding of the complex mechanisms underlying fibrosis, and more specifically, the potential mechanisms-of-action of adipose-derived stomal cells (ADSCs) in realizing their anti-fibrotic effect. METHODS: A systematic review of the literature using PubMed, Embase and Web of Science was performed by two independent reviewers. RESULTS: The injection of fat grafts into fibrotic tissue, releases ADSC into the environment. ADSCs' capacity to directly differentiate into key cell types (e.g., ECs, fibroblasts), as well as to secrete multiple paracrine factors (e.g., hepatocyte growth factor, basis fibroblast growth factor, IL-10), allows them to alter different mechanisms underlying fibrosis in a combined approach. ADSCs favor ECM degradation by impacting the fibroblast-to-myofibroblast differentiation, favoring matrix metalloproteinases over tissue inhibitors of metalloproteinases, positively influencing collagen organization, and inhibiting the pro-fibrotic effects of transforming growth factor-ß1. Furthermore, they impact elements of both the innate and adaptive immune response system, and stimulate angiogenesis on the site of injury (through secretion of pro-angiogenic cytokines like stromal cell-derived factor-1 and vascular endothelial growth factor). CONCLUSION: This review shows that understanding the complex interactions of ECM accumulation, immune response and vascularization, is vital to fibrosis treatments' effectiveness like fat grafting. It details how ADSCs intelligently steer this complex system in an anti-fibrotic or pro-angiogenic direction, without falling into extreme dilation or stimulation of a single aspect. Detailing this combined approach, has brought fat grafting one step closer to unlocking its full potential as a non-anecdotal treatment for fibrosis.

State of the Art of Clinical Applications of Tissue Engineering in 2021.

Tissue engineering (TE) was introduced almost 30 years ago as a potential technique for regenerating human tissues. However, despite promising laboratory findings, the complexity of the human body, scientific hurdles, and lack of persistent long-term funding still hamper its translation toward clinical applications. In this report, we compile an inventory of clinically applied TE medical products relevant to surgery. A review of the literature, including articles published within the period from 1991 to 2020, was performed according to the PRISMA protocol, using databanks PubMed, Cochrane Library, Web of Science, and Clinicaltrials.gov. We identified 1039 full-length articles as eligible; owing to the scarcity of clinical, randomized, controlled trials and case studies, we extended our search toward a broad surgical spectrum. Forty articles involved clinical TE studies. Among these, seven were related to TE protocols for cartilage applied in the reconstruction of nose, ear, and trachea. Nine articles reported TE protocols for articular cartilage, nine for urological purposes, seven described TE strategies for cardiovascular aims, and eight for dermal applications. However, only two clinical studies reported on three-dimensional (3D) and functional long-lasting TE constructs. The concept of generating 3D TE constructs and organs based on autologous molecules and cells is intriguing and promising. The first translational tissue-engineered products and techniques have been clinically implemented. However, despite the 30 years of research and development in this field, TE is still in its clinical infancy. Multiple experimental, ethical, budgetary, and regulatory difficulties hinder its rapid translation. Nevertheless, the first clinical applications show great promise and indicate that the translation toward clinical medical implementation has finally started. Impact statement The clinical use of a tissue-engineered windpipe in compassionate patients elicited euphoria in the media between 2010 and 2016: tissue engineering (TE) had proven to be no longer a fictional concept but a life-saving reality. However, most of the treated patients died, and the surgeon was convicted for scientific misconduct and aggravated assault. As of 2020, the authors had eight of their articles retracted and two received an expression of concern.1 These events have fueled skepticism among clinicians about TE: science or fiction? Although TE is full of promises, it is not realistic yet to engineer a (vascularized) construct that thrives in a "hostile" clinical environment. Therefore, a realistic update of the current clinical outcomes and the promises of TE in human trials are essential.

The Effect of Smoking on the Postoperative Course After Head and Neck Reconstruction With a Vascularized Free Flap: A Retrospective Study.

OBJECTIVES: The objective of the present study is to determine the impact of smoking on hospital and intensive care unit stay, need for surgical reintervention, Portsmouth Physiological and Operative Severity Score for the enumeration of Mortality and morbidity, and surgical complications after head and neck reconstructions. METHODS: All 153 patients who underwent head and neck reconstructions with free tissue transfer at the department of oral and maxillofacial surgery at the University Hospitals of Leuven between January 1, 2015 and December 31, 2018 were enrolled in this retrospective cohort study. Data from medical charts were extracted. Univariate and multiple regression analyses were performed. A level of significance of P < 0.05 (α = 0.05) was used. RESULTS: Smoking was not associated with Portsmouth Physiological and Operative Severity Score for the enumeration of Mortality and morbidity, hospital or ICU stay, the incidence of postoperative complications in both flap and donor site, or surgical reintervention. CONCLUSIONS: Regarding the outcomes included in this study, smoking status should not be considered as a critical factor in patient selection for head and neck reconstructions with a vascularized free flap.

Objectifying growth of vascularized bone transfers after mandibular reconstruction in the pediatric population.

BACKGROUND: Autologous vascularized bone transfer is the preferred strategy for the reconstruction of mandibular defects in a pediatric population. The principal argument is the theoretical postoperative growth potential of the neomandible, which uses vascularized donor tissues. OBJECTIVES: The purpose of this study was to objectify the veritable growth potential of vascularized bone transfers in children. METHODS: A literature search was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, revealing 57 patients younger than or equal to 18 years who had undergone a mandibular reconstruction with a vascularized free flap. Only studies using postoperative imaging were included. Outcomes regarding growth and postoperative corrections and complications were analyzed. RESULTS: Neomandibular growth was observed in 63.2% of all included patients. The proportion of growth was higher in patients with condylar preservation (95.7%) than that of patients with condylar involvement (41.2%). Reconstruction of the condyle by a free flap, which includes an epiphyseal growth plate or cartilage increased postoperative growth potential (77.8%) but did not reduce the need for later orthognathic surgery. CONCLUSION: After mandibular reconstruction with a vascularized bone transfer, the majority of pediatric patients shows neomandibular growth. Condylar preservation, the inclusion of epiphyseal growth plates or cartilage, and the patients age at the time of reconstruction are essential defining parameters.

Treatment of rectus diastasis: should the midline always be reinforced with mesh? A systematic review.

BACKGROUND: Two main trends are described for the treatment of diastasis recti: plication versus midline mesh reinforcement. Indications for these procedures have not been clearly described. This study reviewed the outcomes in the treatment of rectus diastasis with plication versus mesh by the assessment of durability, complications, and patient-reported outcomes. MATERIALS AND METHODS: A systematic review of literature on the treatment of diastasis recti was performed searching through PubMed, Embase, Web of Science, and Cochrane databases. This resulted in 53 eligible articles and predefined inclusion criteria led to the selection of 24 articles. Primary outcomes included recurrence and perioperative complications and secondary outcomes were defined as patient satisfaction, chronic pain, and quality of life. RESULTS: A total of 931 patients were surgically treated for rectus divarication (age range: 18 - 70 years). The most frequently noted comorbidity was obesity and 10.6 percent were smokers. Recurrence was reported in 5 percent of the patients. The most frequent complication was seroma (7 percent), followed by abdominal hypoesthesia (6 percent), and surgical site infection (2 percent). Chronic pain was reported in 4 percent of the patients. Satisfaction was assessed subjectively in the majority of patients and was generally rated as high. Follow-up period ranged from 3 weeks to 20 years. CONCLUSIONS: Durability, safety, and high patient satisfaction support surgical correction of rectus diastasis and could not favor a treatment method. Inter-rectus distance could not be identified as the indicator for technique, which emphasizes that other factors might add to the entity of abdominal wall protrusion more than previously thought.

The current status and outlook of trachea transplantation.

PURPOSE OF REVIEW: The trachea is an enigmatic organ due to its complex morphology. Although circumferential tracheal defects are extremely difficult to repair with autologous tissue or with an allotransplant, the trachea has been touted as the first organ that could be regenerated. This review provides a comprehensive evaluation of the published evidence in tracheal tissue replacement surgery. RECENT FINDINGS: In recent years, reports of successful tracheal regeneration have attracted great interest. Despite descriptions of the trachea as a perhaps uniquely regeneratable tissue since 2008, critical reporting provided insights into the more complex realities of tracheal regeneration attempts and led to the retraction of some articles making tracheal regeneration claims. Allotransplantation of the trachea is hindered by numerous difficult obstacles. The most promising approach developed thus far for difficult-to-repair patch airway defects is tracheal allotransplantation, which allows for tapering and withdrawal of immunosuppressive therapy. SUMMARY: Restoration of a long-segment circumferential tracheal defect remains an unmet challenge. Future clinical studies require thoroughly documented visual evidence of outcomes to reduce confusion surrounding tracheal replacement and to prevent future scandals like those seen previously in the tracheal regeneration story. VIDEO ABSTRACT: http://links.lww.com/COOT/A6.

Immunomodulation as Rescue for Chronic Atonic Skin Wounds.

Chronic skin wounds, caused by arterial or venous insufficiency or by physical pressure, constitute an increasing medical problem as populations age. Whereas typical wounds are characterized by local inflammation that participates in the healing process, atonic wounds lack inflammatory markers, such as neutrophil infiltration, and generally do not heal. Recently, prominent roles in the immunopathology of chronic wounds were attributed to dysregulations in specific cytokines, chemokines, matrix metalloproteinases (MMPs), and their substrates. Together with the complement system, these molecular players provide necessary defense against infections, initiate angiogenesis, and prepare tissue reconstitution. Here, we review the current state of the field and include the concept that, aside from surgery and stem cell therapy, healing may be enhanced by immunomodulating agents.

Reconstruction of defects of the trachea.

The trachea has a complex anatomy to fulfill its tasks. Its unique fibro-cartilaginous structure maintains an open conduit during respiration, and provides vertical elasticity for deglutition, mobility of the neck and speech. Blood vessels pierce the intercartilaginous ligaments to perfuse the ciliated epithelium, which ensures effective mucociliary clearance. Removal of a tracheal segment affected by benign or malignant disease requires airtight restoration of the continuity of the tube. When direct approximation of both tracheal ends is no longer feasible, a reconstruction is needed. This may occur in recurrent short-segment defects in a scarred environment, or in defects comprising more than half the length of the trachea. The resulting gap must be filled with vascularized tissue that restores the mucosal lining and supports the semi-rigid, semi-flexible framework of the trachea. For long-segment or circular defects, restoration of this unique biomechanical profile becomes even more important. Due to the inherent difficulty of creating such a tube, a tracheostomy or palliative stenting are often preferred over permanent reconstruction. To significantly improve and sustain quality of life of these patients, surgeons proposed innovative strategies for complex tracheal repair. In this review, we provide an overview of current clinical applications of tracheal repair using autologous and allogenic tissues. We look at recent advances in the field of tissue engineering, and the areas for improvement of these first human applications. Lastly, we highlight the focus of our research, in an effort to contribute to the development of optimized tracheal reconstructive techniques.

Tissue engineering and surgery: from translational studies to human trials.

Tissue engineering was introduced as an innovative and promising field in the mid-1980s. The capacity of cells to migrate and proliferate in growth-inducing medium induced great expectancies on generating custom-shaped bioconstructs for tissue regeneration. Tissue engineering represents a unique multidisciplinary translational forum where the principles of biomaterial engineering, the molecular biology of cells and genes, and the clinical sciences of reconstruction would interact intensively through the combined efforts of scientists, engineers, and clinicians. The anticipated possibilities of cell engineering, matrix development, and growth factor therapies are extensive and would largely expand our clinical reconstructive armamentarium. Application of proangiogenic proteins may stimulate wound repair, restore avascular wound beds, or reverse hypoxia in flaps. Autologous cells procured from biopsies may generate an 'autologous' dermal and epidermal laminated cover on extensive burn wounds. Three-dimensional printing may generate 'custom-made' preshaped scaffolds - shaped as a nose, an ear, or a mandible - in which these cells can be seeded. The paucity of optimal donor tissues may be solved with off-the-shelf tissues using tissue engineering strategies. However, despite the expectations, the speed of translation of in vitro tissue engineering sciences into clinical reality is very slow due to the intrinsic complexity of human tissues. This review focuses on the transition from translational protocols towards current clinical applications of tissue engineering strategies in surgery.

Updated scar management practical guidelines: non-invasive and invasive measures.

Hypertrophic scars and keloids can be aesthetically displeasing and lead to severe psychosocial impairment. Many invasive and non-invasive options are available for the plastic (and any other) surgeon both to prevent and to treat abnormal scar formation. Recently, an updated set of practical evidence-based guidelines for the management of hypertrophic scars and keloids was developed by an international group of 24 experts from a wide range of specialities. An initial set of strategies to minimize the risk of scar formation is applicable to all types of scars and is indicated before, during and immediately after surgery. In addition to optimal surgical management, this includes measures to reduce skin tension, and to provide taping, hydration and ultraviolet (UV) protection of the early scar tissue. Silicone sheeting or gel is universally considered as the first-line prophylactic and treatment option for hypertrophic scars and keloids. The efficacy and safety of this gold-standard, non-invasive therapy has been demonstrated in many clinical studies. Other (more specialized) scar treatment options are available for high-risk patients and/or scars. Pressure garments may be indicated for more widespread scarring, especially after burns. At a later stage, more invasive or surgical procedures may be necessary for the correction of permanent unaesthetic scars and can be combined with adjuvant measures to achieve optimal outcomes. The choice of scar management measures for a particular patient should be based on the newly updated evidence-based recommendations taking individual patient and wound characteristics into consideration.

Integration of blood outgrowth endothelial cells in dermal fibroblast sheets promotes full thickness wound healing.

Vascularization is the cornerstone of wound healing. We introduced human blood outgrowth endothelial cells (hBOEC) in a self-assembled human dermal fibroblast sheet (hDFS), intended as a tissue-engineered dermal substitute with inherent vascular potential. hBOEC were functionally and molecularly different from early endothelial progenitor cells and human umbilical vein endothelial cells (HUVEC). hBOEC alone, unlike HUVEC, efficiently revascularized and re-oxygenated the wound bed, both by active incorporation into new vessels and by trophic stimulation of host angiogenesis in a dose-dependent manner. Furthermore, hBOEC alone, but not HUVEC, accelerated epithelial coverage and matrix organization of the wound bed. In addition, integration of hBOEC in hDFS not only further improved vascularization, epithelial coverage and matrix organization but also prevented excessive wound contraction. In vitro analyses with hBOEC, fibroblasts and keratinocytes revealed that these effects were both due to growth factor crosstalk and to short cutting hypoxia. Among multiple growth factors secreted by hBOEC, placental growth factor mediated at least in part the beneficial effects on keratinocyte migration and proliferation. Overall, this combined tissue engineering approach paves the way for clinical development of a fully autologous vascularized dermal substitute for patients with large skin defects that do not heal properly.

A plasma-based biomatrix mixed with endothelial progenitor cells and keratinocytes promotes matrix formation, angiogenesis, and reepithelialization in full-thickness wounds.

In search of an autologous vascularized skin substitute, we treated full-thickness wounds (FTWs) with autologous platelet-rich plasma gel (APG) in which we embedded endothelial progenitor cells (EPCs) and basal cell keratinocytes (KCs). We cultivated autologous KCs in low-serum conditions and expanded autologous EPCs from venous blood. FTWs (n = 55) were created on the backs of four pigs, covered with wound chambers, and randomly assigned to the following treatments: (1) APG, (2) APG + KCs, (3) APG + EPCs, (4) APG + KCs + EPCs, and (5) saline. All wounds were biopsied to measure neovascularization (lectin Bandeiraea Simplicifolia-1 (BS-1), alpha smooth muscle actin [alphaSMA], and membrane type 1 matrix metalloproteinase (MT1-MMP)), matrix deposition (fibronectin, collagen type I/III, and alphavbeta3), and reepithelialization. Wound fluids were analyzed for protein expression. All APG-treated wounds showed more vascular structures (p < 0.001), and the addition of EPCs further improved neovascularization, as confirmed by higher lectin, alphaSMA, and MT1-MMP. APG groups had higher collagen I/III (p < 0.05), alphavbeta3, and fibronectin content (p < 0.001), and they exhibited higher concentrations of platelet-derived growth factor subunit bb, basic fibroblast growth factor, hepatocyte growth factor, insulin growth factor-1, transforming growth factor-beta1 and -beta3, matrix metalloproteinase-1 and -z9, and tissue-inhibiting matrix metalloproteinase-1 and -2. Applying APG + KCs resulted in the highest reepithelialization rates (p < 0.001). No differences were found for wound contraction by planimetry. In this porcine FTW model, APG acts as a supportive biomatrix that, along with the embedded cells, improves extracellular matrix organization, promotes angiogenesis, and accelerates reepithelialization.

Cell suspension cultures of allogenic keratinocytes are efficient carriers for ex vivo gene transfer and accelerate the healing of full-thickness skin wounds by overexpression of human epidermal growth factor.

The concept of using growth factor therapy to induce wound repair has been endorsed in studies that show reduced growth factors in wound fluid from chronic and aged wounds. In this study, we used cell suspensions of allogenic keratinocytes as gene-delivery vehicles for human epidermal growth factor (hEGF) and analyzed their impact on wound repair in a porcine wound-healing model. Full-thickness wounds were created on the backs of six Yorkshire pigs and covered with a wound chamber to create a wet wound-healing environment. First, 5 x 10(5) allogenic, autogenic, or mixed keratinocytes were transplanted into wounds and healing parameters were analyzed. Second, we measured long-term reepithelialization and contraction rates from day 8 until day 35. In the third experiment, allogenic keratinocytes were transfected with an hEGF-expressing plasmid pCEP-hEGF and transplanted in full-thickness wounds to improve repair. Wounds treated with autogenic, allogenic, or mixed keratinocytes showed a significantly higher rate of reepithelialization relative to saline-treated control wounds. Repetitive biopsies indicated that the use of allogenic keratinocytes did not lead to long-term wound breakdown. Wounds treated with hEGF-expressing allogenic keratinocytes reepithelialized faster than wounds treated with allogenic keratinocytes or control wounds. With a peak hEGF expression of 920.8 pg/mL, hEGF was detectable until day 5 after transplantation compared with minimal hEGF expression in control wounds. This study shows that allogenic keratinocytes can serve as efficient gene transfer vehicles for ex vivo growth factor delivery to full-thickness wounds and overexpression of hEGF further improves reepithelialization rates.

The gracilis free muscle flap is more than just a "graceful" flap for lower-leg reconstruction.

In 60 consecutive cases, a gracilis free muscle flap was used to reconstruct defects in the lower extremity. Although the harvest of the gracilis free flap is straightforward, the flap is not frequently considered as a valid option for reconstruction because of its "gracile" shape. Hence, it is not considered voluminous enough to cover defects of significant size in the lower leg. However, once the epimysium is separated, the muscle flap spreads out and covers a large surface area, large enough to reconstruct wide rectangular wounds or extended spindleshaped defects. Especially in young patients, the volume of the gracilis muscle is much larger than expected from its descriptive but misleading name. Often it is precisely this patient population that gets involved in motorcycle accidents or traumas caused by contact sports. For the treatment of Gustilo type III open tibia fractures with moderately large-sized soft-tissue defects and for chronic lower leg defects with osteomyelitis, the gracilis muscle flap is an excellent choice. Fifty-nine out of the 60 flaps in long-term follow-up (minimally 3 years) fully healed. The pedicle can be more than 7 cm in length when the final dissection under the long adductor muscle is carried up to the origin at the deep femoral vessels. The functional and aesthetic outcomes at the donor site at the inner thigh are minimal, compared to alternative transfers for such defects, while the reconstructive features of the gracilis muscle flap are excellent.