[Individual Needs of the Patient in Breast Reconstruction - Are There Limits to Plastic Surgery?]

INTRODUCTION: The breast is essential to a woman's physical integrity. There are numerous techniques for breast reconstruction, so that the needs and limitations of each patient can be respected. The individual preferences of the patient play an important role in the decision of silicone implants vs. autologous tissue, size, and shape of the breast as well as the timing of the surgery. The only reasons not to perform a reconstruction are a locally incompletely removed tumor or the explicit wish of the patient against reconstruction. The costs for reconstruction are covered by the health insurance for all procedures, including symmetrizing the opposite breast, nipple reconstruction and autologous fat grafting.

The burn comb model revisited.

INTRODUCTION: The burn comb model is a well-established model for studying secondary burn progression. It creates four rectangular burn surfaces intercalated by three unburned zones prone to secondary burn progression. While burn progression is a tri-dimensional phenomenon, of which the vertical extension from the superficial to deeper tissue layer is clinically most relevant, the models initial focus was mainly on the horizontal surface extension within interspaces. The aim of this study is to evaluate the correlation between horizontal surface and vertical depth burn progression. METHODS: 24 large (400-450 g) Wistar male rats underwent standardized burn injuries using a burn comb. Laser Doppler flowmetry to assess perfusion, planimetric evaluation of burn progression within interspaces and histological analyses assessing burn depth were performed before burn induction (baseline; BL) and after 1 h, as well as after 1, 4, and 7 days. Histological burn depth was graded from superficial (1) to the subcutaneous layer (5). Furthermore, final scarring time and contracture rate were also assessed. RESULTS: The burn comb resulted in consistent and uniform superficial burns (mean ± SEM burn depth score: 2 ± 0; hour 1) separated by intact but critically perfused interspaces (63 ± 1% of BL; p < 0.05 vs. BL). Tissue damage significantly progressed to the deep dermis within the first day (burn depth score 4.3 ± 0.2; p < 0.05 vs. hour 1), while significant interspace necrosis at the surface did not develop within this time period (4 ± 3% of interspace necrosis; p n.s vs. hour 1). However, interspace necrosis was observed at day 4 (83 ± 3%; p < 0.05 vs. hour 1) and further progressed until day 7 (94 ± 2%; p < 0.05 vs. hour 1). CONCLUSION: This study shows the limits of the burn comb model originally described with a discrepancy between horizontal surface and vertical depth progression of the burn injury. We herein propose a necessary refinement of this model to adequately evaluate vertical depth progression using a histological score. This revisited approach focusing on assessment of depth progression of the burn will allow a better evaluation of experimental burn treatments in future.

Long-term pre- and postconditioning with low doses of erythropoietin protects critically perfused musculocutaneous tissue from necrosis.

It has been shown that pre- and postconditioning of ischemically challenged tissue with erythropoietin (EPO) is able to reduce necrosis in a dose-dependent manner. The aim of this study was to determine the tissue-protective effects of different EPO dosages and administration regimes. Three groups of six C57Bl/6-mice each were analyzed: (1) pre- and postconditioning with initial high doses of EPO (starting at 2500 I.U./kg bw i.p.) followed by low doses of EPO (125 I.U./kg bw i.p.) (EPO-high-dose); (2) pre- and postconditioning with low doses of EPO (125 I.U./kg bw i.p.) (EPO-low-dose); and (3) untreated control group. Randomly perfused musculocutaneous flaps were mounted on dorsal skinfold chambers undergoing acute persistent ischemia and developing ∼50% necrosis without treatment. Intravital epifluorescence microscopy was performed at days 1, 3, 5, 7, and 10 after surgery, assessing flap necrosis, microcirculation, and angiogenesis. The hematocrit was measured at days 0, 3, 7, and 10. Only the EPO-low-dose regimen was associated with a significant reduction of necrosis when compared to untreated controls. EPO-low-dose showed a higher increase in both arteriolar diameter and velocity, thereby resulting in a significantly increased arteriolar blood flow and a hence higher functional capillary density (FCD) of the critically perfused zone. EPO-induced angiogenesis was significantly increased in EPO-low-dose at days 7 and 10. Only EPO-high-dose reached a significant hematocrit increase by day 10. Tissue pre- and postconditioning with low doses of EPO protects the critically perfused musculocutaneous tissue by maintaining capillary perfusion because of increased arteriolar blood flow mediated by nitric oxide (NO) expression.

Nanofat Grafting for Scar Treatment and Skin Quality Improvement.

BACKGROUND: Fat grafting has been gaining attention in tissue augmentation over the past decade, not only for lipofilling, but also for its observed regenerative properties and overall skin texture improvement. OBJECTIVES: The aim of this study was to analyze the effect of nanofat grafting on scars, wrinkles, and skin discolorations in our clinic. METHODS: Nanofat was prepared by a standard emulsification and filtration protocol. The resulting liquid was injected intradermally or directly into the scar tissue. Skin quality was evaluated based on a scoring system, and patient satisfaction was documented. Three physicians compared and analyzed standardized pre- and posttreatment photographs in respect to general improvement of skin aesthetics. RESULTS: Fifty-two patients were treated with nanofat from November 2013 to April 2016. The mean (± standard deviation) posttreatment follow up was 155 ± 49 days and average volume of harvested fat amounted to 165 cc. The primary harvesting areas were the abdomen and flanks, and the injected volume of nanofat ranged from 1 to 25 mL (mean, 4.6 mL). A total of 40 scars (76% of all patient defects) were effectively treated as well as 6 patients with wrinkles, and 6 patients with discoloration. Posttreatment clinical evaluations showed a marked improvement of scar quality and a high patient satisfaction. The results in our clinic showed that nanofat grafting softened the scars, made discolorations less pronounced, and wrinkles appeared less prominent. CONCLUSIONS: Nanofat grafting has been shown to have beneficial effects in the treatment of scars, wrinkles, and skin discolorations.

Free Diced Cartilage: A New Application of Diced Cartilage Grafts in Primary and Secondary Rhinoplasty.

BACKGROUND: Irregularities or deformities of the nasal dorsum after hump reduction account for a significant number of revision rhinoplasties. The authors therefore developed a technique of meticulously dicing and exactly placing free diced cartilage grafts, harvested from septum, rib, or ear cartilage. The cartilage paste is used for smoothening, augmentation, or camouflaging of the nasal dorsum in primary or revision rhinoplasties. METHODS: A retrospective analysis of multisurgeon consecutive open approach rhinoplasties from January to December of 2014 was conducted at a single center. The authors compared the outcome of three different techniques to augment or cover the nasal dorsum after an observation period of 7 months. In group I, 325 patients with free diced cartilage grafts as the only onlay were included. In group II, consisting of 73 patients, the dorsal onlay was either fascia alone or in combination with free diced cartilage grafts. Forty-eight patients in group III received a dorsal augmentation with the classic diced cartilage in fascia technique. RESULTS: Four hundred forty-six patients undergoing primary and secondary rhinoplasties in which one of the above-mentioned diced cartilage techniques was used were included in the study. The authors found revision rates for dorsal irregularities within the 7-month postoperative observation period of 5.2, 8.2, and 25 percent for groups I, II, and III, respectively. CONCLUSION: The authors' findings strongly support their clinical experience that the free diced cartilage graft technique presents an effective and easily reproducible method for camouflage and augmentation in aesthetic and reconstructive rhinoplasty.

Sensory reanimation of the hand by transfer of the superficial branch of the radial nerve to the median and ulnar nerve.

BACKGROUND: It remains a surgical challenge to treat high-grade nerve injuries of the upper extremity. Extra-anatomic reconstructions through the transfer of peripheral nerves have gained clinical importance over the past decades. This contribution outlines the anatomic and histomorphometric basis for the transfer of the superficial branch of the radial nerve (SBRN) to the median nerve (MN) and the superficial branch of the ulnar nerve (SBUN). METHODS: The SBRN, MN, and SBUN were identified in 15 specimens and the nerve transfer performed. A favorable site for coaptation was chosen and its location described using relevant anatomical landmarks. Histomorphometric characteristics of donor and target were compared to evaluate the chances of a clinical success. RESULTS: A suitable location for dissecting the SBRN was identified prior to its first bifurcation. Coaptations were possible near the pronator quadratus muscle, approximately 22 cm distal to the lateral epicondyle of the humerus. The MN and SBUN had to be dissected interfasciculary over 82 ± 5.7 mm and 49 ± 5.5 mm, respectively. Histomorphometric analysis revealed sufficient donor-to-recipient axon ratios for both transfers and identified the SBRN as a suitable donor with high axon density. CONCLUSION: Our anatomic and histomorphometric results indicate that the SBRN is a suitable donor for the MN and SBUN at wrist level. The measurements show feasibility of this procedure and shall help in planning this sensory nerve transfer. High axon density in the SBRN identifies it or its branches an ideal candidate for sensory reanimation of fingers and thumbs.

Nasal Reconstruction: Extending the Limits.

Reconstructing the 3-dimensional structure of the nose requires the maintenance of its aesthetic form and function. Restoration of the correct dimension, projection, skin quality, symmetrical contour, and function remains problematic. Consequently, modern approaches of nasal reconstruction aim at rebuilding the units rather than just covering the defect. However, revising or redoing a failed or insufficient reconstruction remains very challenging and requires experience and creativity. Here, we present a very particular case with a male patient, who underwent 37 operations elsewhere and presented with a failed nasal reconstruction. We describe and illustrate the complex steps of the nasal rereconstruction, including the reconstruction of the forehead donor site, surgical delay procedures for lining, and the coverage with a third paramedian forehead flap.

New Suturing Techniques to Reconstruct the Keystone Area in Extracorporeal Septoplasty.

BACKGROUND: Severe septal deformations require adequate treatment to restore shape and function using extracorporeal septoplasty. Because it has been criticized for being technically demanding to execute and has increased risk for aesthetic complications, the authors have developed two new suture techniques for refixation of the neoseptum. METHODS: A retrospective analysis of multisurgeon consecutive extracorporeal septoplasties performed from January of 2014 to December of 2014 was conducted at a single institution using the criss-cross or transcutaneous transosseous cerclage suture (group 1) compared with fixation at the upper lateral cartilages only (group 2). RESULTS: One hundred ten extracorporeal septoplasties were performed in 110 patients over 12 months. Group 1 consisted of 58 patients (53 percent), whether receiving the criss-cross [12 patients (21 percent)] or the transcutaneous transosseous cerclage suture [46 patients (79 percent)], and group 2 consisted of 52 patients (47 percent). The median follow-up was 11 months (range, 6 to 16 months). Operative revision because of complications at the dorsum or the keystone area had to be performed in no case in group 1 and in five cases (9.6 percent) in group 2, resulting in a statistically significant difference between the two groups (p = 0.0212). There were no complications such as bleeding or infection observed in any of the 110 cases. CONCLUSIONS: To facilitate and to reduce the complication rate after extracorporeal septoplasty, the authors have developed the criss-cross and transcutaneous transosseous cerclage suture to overcome the important and technically demanding reimplantation of the neoseptum. Thus, the authors believe that these new operative techniques are safe and reproducible procedures that may take a permanent place among extracorporeal septoplasty procedures. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Animal models in surgical lymphedema research--a systematic review.

BACKGROUND: Chronic secondary lymphedema is a well-known complication in oncologic surgery. Autologous lymph node transplantation, lymphovenous anastomosis, and other lymphatic surgeries have been developed in the last decades with rising clinical application. Animal models to explore the pathophysiology of lymphedema and microsurgical interventions have reached great popularity, although the induction of stable lymphedema in animals is still challenging. The aim of this review was to systematically assess lymphedema animal models and their potential use to study surgical interventions. MATERIALS AND METHODS: A systematic review according to the PRISMA guidelines was performed without time or language restriction. Studies describing new or partially new models were included in chronological order. Models for primary and secondary lymphedema were assessed, and their potential for surgical procedures was evaluated. RESULTS: The systematic search yielded 8590 discrete articles. Of 180 articles included on basis of title, 84 were excluded after abstract review. Ninety-six were included in the final analysis with 24 key articles. CONCLUSIONS: No animal model is perfect, and many models show spontaneous lymphedema resolution. The rodent limb appears to be the most eligible animal model for experimental reconstruction of the lymphatic function as it is well accessible for vascularized tissue transfer. There is a need for standardized parameters in experimental lymphedema quantification. Also, more permanent models to study the effect of free vascularized lymph node transfer are needed.

Treatment of secondary burn wound progression in contact burns-a systematic review of experimental approaches.

After a burn injury, superficial partial-thickness burn wounds may progress to deep partial-thickness or full-thickness burn wounds, if kept untreated. This phenomenon is called secondary burn wound progression or conversion. Burn wound depth is an important determinant of patient morbidity and mortality. Therefore, reduction or even the prevention of secondary burn wound progression is one goal of the acute care of burned patients. The objective of this study was to review preclinical approaches evaluating therapies to reduce burn wound progression. A systematic review of experimental approaches in animals that aim at reducing or preventing secondary burn wound progression was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta Analysis (PRISMA) guidelines. The selected references consist of all the peer-reviewed studies performed in vivo in animals and review articles published in English, German, Italian, Spanish, or French language relevant to the topic of secondary burn wound progression. We searched MEDLINE, Cochrane Library, and Google Scholar including all the articles published from the beginning of notations to the present. The search was conducted between May 3, 2012 and December 26, 2013. We included 29 experimental studies in this review, investigating agents that maintain or increase local perfusion conditions, as well as agents that exhibit an anti-coagulatory, an anti-inflammatory, or an anti-apoptotic property. Warm water, simvastatin, EPO, or cerium nitrate may represent particularly promising approaches for the translation into clinical use in the near future. This review demonstrates promising experimental approaches that might reduce secondary burn wound progression. Nevertheless, a translation into clinical application needs to confirm the results compiled in experimental animal studies.

Ischemic tissue injury in the dorsal skinfold chamber of the mouse: a skin flap model to investigate acute persistent ischemia.

Despite profound expertise and advanced surgical techniques, ischemia-induced complications ranging from wound breakdown to extensive tissue necrosis are still occurring, particularly in reconstructive flap surgery. Multiple experimental flap models have been developed to analyze underlying causes and mechanisms and to investigate treatment strategies to prevent ischemic complications. The limiting factor of most models is the lacking possibility to directly and repetitively visualize microvascular architecture and hemodynamics. The goal of the protocol was to present a well-established mouse model affiliating these before mentioned lacking elements. Harder et al. have developed a model of a musculocutaneous flap with a random perfusion pattern that undergoes acute persistent ischemia and results in ~50% necrosis after 10 days if kept untreated. With the aid of intravital epi-fluorescence microscopy, this chamber model allows repetitive visualization of morphology and hemodynamics in different regions of interest over time. Associated processes such as apoptosis, inflammation, microvascular leakage and angiogenesis can be investigated and correlated to immunohistochemical and molecular protein assays. To date, the model has proven feasibility and reproducibility in several published experimental studies investigating the effect of pre-, peri- and postconditioning of ischemically challenged tissue.

A full skin defect model to evaluate vascularization of biomaterials in vivo.

Insufficient vascularization is considered to be one of the main factors limiting the clinical success of tissue-engineered constructs. In order to evaluate new strategies that aim at improving vascularization, reliable methods are required to make the in-growth of new blood vessels into bio-artificial scaffolds visible and quantify the results. Over the past couple of years, our group has introduced a full skin defect model that enables the direct visualization of blood vessels by transillumination and provides the possibility of quantification through digital segmentation. In this model, one surgically creates full skin defects in the back of mice and replaces them with the material tested. Molecules or cells of interest can also be incorporated in such materials to study their potential effect. After an observation time of one's own choice, materials are explanted for evaluation. Bilateral wounds provide the possibility of making internal comparisons that minimize artifacts among individuals as well as of decreasing the number of animals needed for the study. In comparison to other approaches, our method offers a simple, reliable and cost effective analysis. We have implemented this model as a routine tool to perform high-resolution screening when testing vascularization of different biomaterials and bio-activation approaches.

Blue dye injection does not induce dissemination of epithelial cells during SLN procedure in colon cancer patients.

INTRODUCTION: The sentinel lymph node (SLN) procedure for colon cancer patients has been increasingly performed over the past decade and has shown advantages regarding lymph node staging. However, there are concerns that the manipulation of the colon, particularly the blue dye injection, results in isolated tumor cell dissemination to lymph nodes. Therefore, the objective of the present study was to evaluate whether the blue dye injection during the SLN procedure for colon cancer induces epithelial cell dissemination to the regional lymph nodes using a fake SLN procedure as a model. METHODS: One hundred seventy-four colon cancer patients underwent open oncologic colon resection and SLN procedure according to a standardized protocol. For the fake SLN procedure, blue dye was injected ex vivo, into the subserosa of a nontumor-bearing segment of the resected colon in 37 unselected patients. Three levels of each SLN were stained with H&E and with the pancytokeratin marker AE1/AE3 and were analyzed for the presence of cytokeratin positive cells. RESULTS: Identification of fake SLN was successful in 32 of the 37 patients (86 %). Seventy fake SLN were histologically confirmed. The median number of fake SLN was 2 per patient (range 1-8). None of the fake SLN showed any disseminated epithelial cells. CONCLUSIONS: The present prospective study provides compelling evidence that blue dye injection during sentinel lymph node procedure for colon cancer does not induce epithelial cell dissemination to the sentinel lymph nodes. Therefore, isolated tumor cells in sentinel lymph nodes result from a true metastatic process.

Surgical sutures filled with adipose-derived stem cells promote wound healing.

Delayed wound healing and scar formation are among the most frequent complications after surgical interventions. Although biodegradable surgical sutures present an excellent drug delivery opportunity, their primary function is tissue fixation. Mesenchymal stem cells (MSC) act as trophic mediators and are successful in activating biomaterials. Here biodegradable sutures were filled with adipose-derived mesenchymal stem cells (ASC) to provide a pro-regenerative environment at the injured site. Results showed that after filling, ASCs attach to the suture material, distribute equally throughout the filaments, and remain viable in the suture. Among a broad panel of cytokines, cell-filled sutures constantly release vascular endothelial growth factor to supernatants. Such conditioned media was evaluated in an in vitro wound healing assay and showed a significant decrease in the open wound area compared to controls. After suturing in an ex vivo wound model, cells remained in the suture and maintained their metabolic activity. Furthermore, cell-filled sutures can be cryopreserved without losing their viability. This study presents an innovative approach to equip surgical sutures with pro-regenerative features and allows the treatment and fixation of wounds in one step, therefore representing a promising tool to promote wound healing after injury.

Local shockwave-induced capillary recruitment improves survival of musculocutaneous flaps.

BACKGROUND: Shockwave (SW) application has been shown to limit flap necrosis. However, the underlying microhemodynamic mechanisms remain unclear. Therefore, the objective of this study was to analyze the effect of SW application on a microcirculatory level. METHODS: We treated 12 C57BL/6 mice with local SW application (500 shockwave impulses at 0.15 mJ/mm(2)) either 24 h before (preconditioning [PRE]) or 30 min after (postconditioning [POST]) flap elevation. Animals with an untreated flap (CON) or without a flap served as controls. We applied dorsal skinfold chambers to the animals and performed epifluorescence microscopy over a 10-d period to assess microcirculatory parameters (arteriolar diameter, red blood cell velocity, blood flow, functional capillary density, and intercapillary distance) as well as inflammation, apoptotic cell death, and necrosis. RESULTS: SW application significantly decreased tissue necrosis independently of the application time point (PRE: 29% ± 7%; POST: 25% ± 7% versus CON: 47% ± 2%; day 10, P < 0.05). Arteriolar diameter, red blood cell velocity, and blood flow were not statistically significantly different among the 3 flap groups. However, SW (PRE and POST) resulted in an early and persistent increase in functional capillary density and consequently decreased intercapillary distance compared with CON and the group without a flap (P < 0.05). Also, SW resulted in a significantly decreased inflammatory response (P < 0.05) and induced an angiogenic response, as indicated by new functional microvessel formation observed 5 d after therapy. CONCLUSIONS: Local SW application improved tissue survival by recruitment of sleeping capillaries within the non ischemic tissue and maintenance of capillary perfusion within the critically perfused tissue after induction of ischemia, which was independent of the application time point. Neoangiogenesis occurred beyond the ischemic tolerance of the tissue, and therefore does not seem to contribute to improved tissue survival.

Long-term preconditioning with erythropoietin reduces ischemia-induced skin necrosis.

OBJECTIVE: Recent findings have attested to EPO tissue-protective effects in ischemically challenged tissues. Therefore, the study aimed at elaborating the effect of systemic pre- and postconditioning using EPO in a mouse model of persistent ischemia of the skin. METHODS: Three groups of nine C57Bl/6-mice each were analyzed. The experimental groups consisted of untreated controls, EPO preconditioning, and EPO postconditioning (500 IU EPO/kg bw/day for 10 days). Critically perfused skin flaps undergoing necrosis, if kept untreated, were mounted into dorsal skinfold chambers. Intravital epi-fluorescence microscopy was performed for 10 days to assess tissue necrosis, microcirculation, inflammation, and angiogenesis. Protein expression analysis of eNOS was performed. Hematocrit analyses were carried out separately in eight animals. RESULTS: Only EPO preconditioning was able to significantly reduce necrosis, when compared with controls. This correlated with a significantly increased CD in the critically perfused tissue. Administration of EPO only slightly increased eNOS expression at day 10, when compared with controls. EPO induced angiogenesis and increased hematocrit. Finally, EPO significantly reduced leukocytic inflammation in arterioles in all EPO receiving mice. CONCLUSIONS: EPO preconditioning effectively reduces skin necrosis predominantly by capillary maintenance and reperfusion, as well as improved tissue regeneration. Thus, EPO preconditioning might represent a promising, non-invasive approach to reduce complications in ischemically challenged skin.

Secondary burn progression decreased by erythropoietin.

OBJECTIVE: To investigate whether systemic erythropoietin administration can prevent secondary burn progression in an experimental model and to elucidate the underlying mechanisms. DESIGN: Prospective study. SETTING: University-based laboratory research. SUBJECTS: Twenty-one male Wistar rats. INTERVENTIONS: The burn comb model creates four rectangular burned surfaces that are intercalated by three unburned zones (interspaces) prone to secondary necrosis. Twenty-one animals were randomized to three experimental groups: 1) Local cooling with water for 20 minutes (control, 17°C); 2) and 3) local cooling with water and intraperitoneal erythropoietin once a day for five days starting 45 minutes after burn injury (500 IU/kg body weight: EPO 500 or 2500 IU/kg body weight: EPO 2500). MEASUREMENTS AND MAIN RESULTS: Secondary burn progression-both in depth (histology) and in surface (planimetry)-as well as interspace perfusion (laser Doppler flowmetry) and hematocrit were analyzed. Further, dilatory response (inducible nitric oxide synthase expression), inflammation (leukocyte count), and angiogenesis (CD31 expression) were assessed. Finally, wound healing time and contracture rate were reported. Burn progression resulted in complete dermal destruction as well as in important interspace necrosis in control animals, whereas burn progression was significantly reduced in a dose-dependent manner in animals treated with erythropoietin. Tissue protection was associated with an increased interspace perfusion with EPO 500, but not with EPO 2500, and was paralleled by a significant increase in inducible nitric oxide synthase expression and decreased inflammation, independent of the erythropoietin dosage. EPO 2500 led to a significant increase of hematocrit at day 4. Finally, faster wound healing and less contracture were observed in animals treated with EPO 500 only. CONCLUSIONS: Erythropoietin represents an easy-to-use therapeutic approach to prevent secondary burn progression, i.e., to control damage after burn injury. It preserves microcirculatory perfusion within the endangered areas in a dose-dependent manner.

Tissue banking in a regional hospital: a promising future concept? First report on fresh frozen tissue banking in a hospital without an integrated institute of pathology.

BACKGROUND: Vital tissue provided by fresh frozen tissue banking is often required for genetic tumor profiling and tailored therapies. However, the potential patient benefits of fresh frozen tissue banking are currently limited to university hospitals. The objective of the present pilot study--the first one in the literature--was to evaluate whether fresh frozen tissue banking is feasible in a regional hospital without an integrated institute of pathology. METHODS: Patients with resectable breast and colon cancer were included in this prospective study. Both malignant and healthy tissue were sampled using isopentan-based snap-freezing 1 h after tumor resection and stored at -80 °C before transfer to the main tissue bank of a University institute of pathology. RESULTS: The initial costs to set up tissue banking were 35,662 US$. Furthermore, the running costs are 1,250 US$ yearly. During the first 13 months, 43 samples (nine samples of breast cancer and 34 samples of colon cancer) were collected from 41 patients. Based on the pathology reports, there was no interference with standard histopathologic analyses due to the sample collection. CONCLUSIONS: This is the first report in the literature providing evidence that tissue banking in a regional hospital without an integrated institute of pathology is feasible. The interesting findings of the present pilot study must be confirmed by larger investigations.

Erythropoietin-induced upregulation of endothelial nitric oxide synthase but not vascular endothelial growth factor prevents musculocutaneous tissue from ischemic damage.

Recent findings have attested the protective effects of erythropoietin (EPO) in ischemically challenged organs. We therefore aimed at elaborating the underlying mechanism of EPO-mediated protection in musculocutaneous tissue undergoing persistent ischemia after acute injury. Mice were assigned to five experimental groups equipped with a randomly perfused flap fixed in a dorsal skinfold chamber, whereas the sixth group did not undergo flap preparation: EPO, L-Name, EPO and L-Name, EPO and bevacizumab, untreated flap, and nonischemic chamber (control). Intravital fluorescence microscopic analysis of microhemodynamics, apoptotic cell death, macromolecular leakage and angiogenesis was carried out over a 10-day period. Further, immunohistochemical analysis was used to study the protein expression of endothelial nitric oxide synthase (eNOS) and vascular endothelial growth factor (VEGF). Increased expression of eNOS in EPO-administered mice correlated with significant arteriolar dilation and thus increased blood flow resulting in a maintained functional capillary density (FCD) at day 10. In addition, EPO induced a VEGF upregulation, which was associated with newly formed capillaries. In addition, EPO was able to reduce ischemia-induced apoptotic cell death and finally to significantly reduce flap necrosis. In contrast, coadministration of L-Name abolished EPO-mediated tissue protection by abrogating the dilatory effect resulting in reduced FCD and tissue survival, without counteracting angiogenesis and apoptotic cell death, whereas additional administration of bevacizumab did not influence the beneficial effect of EPO on flap survival despite abrogating angiogenesis. Macromolecular leakage was found to be increased in all treatment groups. This study shows that EPO administration prevents musculocutaneous tissue from ischemic necrosis as a consequence of an eNOS-dependent arteriolar hyperperfusion maintaining capillary perfusion, thus representing a promising approach to pharmacologically protect ischemically challenged tissue.

Erythropoietin protects critically perfused flap tissue.

OBJECTIVE: The objective of this study was to analyze whether erythropoietin (EPO) protects from necrosis of critically perfused musculocutaneous tissue and the mechanisms by which this protection is achieved. BACKGROUND: EPO is the regulator of erythropoiesis and is used to treat patients with anemia of different causes. Recent studies suggest that EPO has also other tissue-protective effects, irrespective of its erythropoietic properties. MATERIAL AND METHODS: C57BL/6-mice were treated with 3 doses of EPO at 500 IU/kg intraperitoneally. EPO was given either before (preconditioning, n = 7), before and after (overlapping treatment, n = 7), or after (treatment, n = 7) surgery. Animals receiving only saline served as controls (CON). Acute persistent ischemia was induced by elevating a randomly perfused flap in the back of the animals. This critically perfused tissue demonstrates an initial microvascular failure of approximately 40%, resulting in approximately 50% tissue necrosis if kept untreated. Repetitive fluorescence microscopy was performed over 10 days, assessing angiogenesis, functional capillary density, inflammatory leukocyte-endothelial cell interaction, apoptotic cell death, and tissue necrosis. Additional molecular tissue analyses included the determination of inducible nitric oxide synthase, erythropoietin receptor (EPO-R), and vascular endothelial growth factor (VEGF). RESULTS: EPO preconditioning did not affect hematocrit and EPO-R expression, but increased inducible nitric oxide synthase in the critically perfused tissue. This correlated with a significant arteriolar dilation, which resulted in a maintained functional capillary density (CON: 0 +/- 0 cm/cm(2); preconditioning: 37 +/- 21 cm/cm(2); overlapping treatment: 72 +/- 26 cm/cm(2); P < 0.05). EPO pretreatment further significantly reduced microvascular leukocyte adhesion and apoptotic cell death. Moreover, EPO pretreatment induced an early VEGF upregulation, which resulted in new capillary network formation (CON: 0 +/- 0 cm/cm(2); preconditioning: 40 +/- 3 cm/cm(2); overlapping treatment: 33 +/- 3 cm/cm(2); P < 0.05). Accordingly, EPO pretreatment significantly reduced tissue necrosis (CON: 48% +/- 2%; preconditioning: 26% +/- 3%; overlapping treatment: 20% +/- 3%; P < 0.05). Of interest, EPO treatment was only able to alleviate ischemia-induced inflammation but could not improve microvascular perfusion and tissue survival. CONCLUSIONS: EPO pretreatment improves survival of critically perfused tissue by nitric oxide -mediated arteriolar dilation, protection of capillary perfusion, and VEGF-initiated new blood vessel formation.