Combining Allograft Adipose and Fascia Matrix as an Off-the-Shelf Scaffold for Adipose Tissue Engineering Stimulates Angiogenic Responses and Activates a Proregenerative Macrophage Profile in a Rodent Model.

OBJECTIVE: Bioscaffolds for treating soft tissue defects have limitations. As a bioscaffold, allograft adipose matrix (AAM) is a promising approach to treat soft tissue defects. Previously, we revealed that combining superficial adipose fascia matrix with AAM, components of the hypodermis layer of adipose tissue, improved volume retention, adipogenesis, and angiogenesis in rats 8 weeks after it was implanted compared with AAM alone. Here, we modified the fascia matrix and AAM preparation, examined the tissue over 18 weeks, and conducted a deeper molecular investigation. We hypothesized that the combined matrices created a better scaffold by triggering angiogenesis and proregenerative signals. METHODS: Human AAM and fascia matrix were implanted (4 [1 mL] implants/animal) into the dorsum of male Fischer rats (6-8 weeks old; ~140 g) randomly as follows: AAM, fascia, 75/25 (AAM/fascia), 50/50, and 50/50 + hyaluronic acid (HA; to improve extrudability) (n = 4/group/time point). After 72 hours, as well as 1, 3, 6, 9, 12, and 18 weeks, graft retention was assessed by a gas pycnometer. Adipogenesis (HE), angiogenesis (CD31), and macrophage infiltration (CD80 and CD163) were evaluated histologically at all time points. The adipose area and M1/M2 macrophage ratio were determined using ImageJ. RNA sequencing (RNA-seq) and bioinformatics were conducted to evaluate pathway enrichments. RESULTS: By 18 weeks, the adipose area was 2365% greater for 50/50 HA (281.6 ± 21.6) than AAM (11.4 ± 0.9) (P < 0.001). The M1/M2 macrophage ratio was significantly lower for 50/50 HA (0.8 ± 0.1) than AAM (0.9 ± 0.1) at 6 weeks (16%; P < 0.05). This inversely correlated with adipose area (r = -0.6; P > 0.05). The RNA-seq data revealed that upregulated adipogenesis, angiogenesis, and macrophage-induced tissue regeneration genes were temporally different between the groups. CONCLUSIONS: Combining the fascia matrix with AAM creates a bioscaffold with an improved retention volume that supports M2 macrophage-mediated angiogenesis and adipogenesis. This bioscaffold is worthy of further investigation.

Asymptomatic Stroke After Hyaluronic Acid Filler Injection: Case Report and Literature Review.

Vascular compromise and blindness are reported but rare complications of facial soft tissue filler injections. Stroke is an even rarer complication resulting from intraarterial injection of fillers. We present a case of a patient suffering all 3 complications following hyaluronic acid filler injection: forehead skin vascular compromise, unilateral blindness, and ipsilateral subclinical strokes. Were it not for a stroke workup protocol, the incidental strokes may have otherwise gone undetected, suggesting the incidence of stroke from intraarterial injection may be higher than reported. Further, we review the literature and recommendations for prevention and management of threatened tissue ischemia and vision loss from facial filler injection.

Mesenchymal stem cell dysfunction in diabetes.

Diabetes mellitus (DM) is a chronic disease that results in a variety of systemic complications. Recently, stem cell-based therapies have been proposed as potential modalities to manage DM related complications. Mesenchymal stem cell (MSC) based therapies are often considered as an ideal stem cell-based treatment for DM management due to their immunosuppressive characteristics, anti-inflammatory properties and differentiation potential. While MSCs show tremendous promise, the underlying functional deficits of MSCs in DM patients is not well understood. Using the MEDLINE database to define these functional deficits, our search yielded 1826 articles of which 33 met our inclusion criteria. This allowed us to review the topic and illuminate four major molecular categories by which MSCs are compromised in both Type 1 DM and Type II DM models which include: (1) changes in angiogenesis/vasculogenesis, (2) altered pro-inflammatory cytokine secretion, (3) increased oxidative stress markers and (4) impaired cellular differentiation and decreased proliferation. Knowledge of the deficits in MSC function will allow us to more clearly assess the efficacy of potential biologic therapies for reversing these dysfunctions when treating the complications of diabetic disease.

The Molecular Pathogenesis of Dupuytren Disease: Review of the Literature and Suggested New Approaches to Treatment.

BACKGROUND: Ever since the classification of Dupuytren disease into the proliferative, involutional, and residual stages, extensive research has been performed to uncover the molecular underpinnings of the disease and develop better treatment modalities for patients. The aim of this article is to systematically review the basic science literature pertaining to Dupuytren disease and suggest a new approach to treatment. METHODS: Following Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, a systematic review was conducted using the MEDLINE database to identify basic science literature on Dupuytren pathophysiology falling under 1 or more of the following categories: (1) Molecular alterations, (2) Structural alterations, and (3) Genetic predisposition. RESULTS: A total of 177 articles were reviewed of which 77 studies met inclusion criteria. Articles were categorized into respective sections outlined in the study methods. CONCLUSION: The pathophysiological changes involved in Dupuytren's disease can be divided into a number of molecular and structural alterations with genetic predisposition playing a contributory role. Understanding these changes can allow for the development of biologics which may disrupt and halt the disease process.

Micro/nanobubbles: Improving Pancreatic Islet Cell Survival for Transplantation.

PURPOSE: The preservation of transplantable tissue is directly tied to and limited by the ischemia time. Micro/nanobubbles (MNBs) are miniature gaseous voids that allow for the oxygenation of tissue given their high oxygen-carrying capacity. One of the current limitations of islet cell transplantation for type 1 diabetes is poor islet survival, caused by hypoxia, after harvesting the cells from pancreata. As such, the purpose of this study was to elucidate whether MNBs, when added to standard culture medium, improve islet cell survival postharvest. MATERIALS AND METHODS: Islet cells were harvested from Sprague-Dawley rat pancreas tissue via a standard collagenase digestion and gradient purification. To create the MNB solution, a shear-based generation system was used to produce both air- and oxygen-filled MNBs in standard Connaught Medical Research Laboratories (CMRL) medium. Four groups, consisting of 500 islet equivalents, were cultured with either the standard CMRL medium, macrobubble-CMRL, MNB (air)-CMRL, or MNB (O2)-CMRL, and they were incubated at 37°C. Each treatment solution was replenished 24 hours postincubation, and after 48 hours of culture, dithizone staining was used to determine the islet cell counts, and the viability was assessed using Calcein AM/propidium iodide staining. RESULTS: Islet cells that were preserved in macrobubble-CMRL, MNB (air)-CMRL, and MNB (O2)-CMRL conditions showed an increased survival compared with those cultured with standard CMRL. The islet cells cultured in the MNB (air)-CMRL condition demonstrated the greatest cell survival compared with all other groups, including the pure oxygen-carrying MNBs. None of the MNB treatments significantly altered the viability of the islet cells compared to the control condition. CONCLUSIONS: The addition of MNBs to culture medium offers an innovative approach for the oxygenation of transplantable tissue, such as islet cells. This study demonstrated that MNBs filled with air provided the most optimal addition to the islet cell culture medium for improving islet cell survival amongst the treatment groups we tested. Given these findings, we hypothesize that MNBs may also improve the oxygenation and survival of a variety of other tissues, including fat grafts from lipoaspirate, chronic wounds, and solid organs.

Microsurgery Training Resource Variation among US Integrated Plastic Surgery Residency Programs.

BACKGROUND: Given emerging focus on competency-based surgical training and work-hour limitations, surgical skills laboratories play an increasingly important role in resident education. This study was designed to investigate educational opportunities in microsurgery across integrated residency programs. METHODS: Senior residents (PGY 4-6) at integrated plastic surgery programs were surveyed during the 2016 to 2017 academic year to determine each program's access to: training microscopes and anastomosis models, video-based skills assessment, pre-requisite skills exams, flap courses, or a formal microsurgical training curriculum. Programs were stratified based on large size (>18 residents) and presence of microsurgery fellows. Chi-squared analysis was performed with p < 0.05 to assess statistical significance. RESULTS: Survey responses were collected from 32 of 60 eligible programs (53% response rate). Sixty-nine percent provide access to one to two training microscopes, 25% provide three or more, and 6% provide none. Sixty-nine percent of programs train anastomosis with nonliving prosthetics, 66% with living biologics, and 50% with nonliving biologics. Large program size or having microsurgical fellows was not associated with increased access to training microscopes or specific anastomosis models. Programs without microsurgery fellows reported more often that a formal microsurgery curriculum would be helpful (90 vs. 58% of programs with fellows, p = 0.0003). Respondents who indicated that creating a formal curriculum would not be helpful elaborated that their program already has a formal curriculum or a high volume of microsurgery cases. CONCLUSION: This study demonstrates the current variation in microsurgery training at integrated plastic surgery residency programs. A formal microsurgical training curriculum is commonly viewed as being helpful, particularly at programs without microsurgery fellows.

Work-Related Musculoskeletal Discomfort and Injury in Microsurgeons.

BACKGROUND: Long surgical procedures with loupe magnification and microscopes may put microsurgeons at an increased risk of musculoskeletal discomfort. Identifying the prevalence and impact of work-related musculoskeletal discomfort may guide preventive strategies to prolong well-being, job satisfaction, and career duration. METHODS: An online 29-question survey was designed to evaluate work-related musculoskeletal discomfort. The survey was created and distributed electronically through a private survey research center and was sent to the members of the American Society for Reconstructive Microsurgery. RESULTS: There were 117 respondents (16.7% response rate): 80% were men; 69% were aged 31 to 50 years; and 68% were in academic practice. On a scale of 0 to 10 (0, no pain and 10, worst pain), the median for work-related musculoskeletal discomfort for surgery without loupes or microscope was 2; with loupes, 4; and with a microscope, 5. Pain was most common in the neck. Half of the surgeons reported pain within 4 hours of surgery, and 57% feared that pain would influence future surgical performance. Surgeon discomfort affected posture (72%), stamina (36%), sleep (29%), relationships (25%), concentration (22%), and surgical speed (19%). Tremor caused by the discomfort occurred in 8%. Medical treatment for discomfort was sought by 29%. Time off work for treatment occurred for 8%. CONCLUSION: Work-related musculoskeletal discomfort can affect many aspects of a microsurgeon's life and has the potential to limit a surgeon's ability to operate. Therefore, more emphasis is needed in the surgical community on the important issues of occupational health and surgical ergonomics for microsurgeons.

The New Frontier: A Review of Augmented Reality and Virtual Reality in Plastic Surgery.

Mixed reality, a blending of the physical and digital worlds, can enhance the surgical experience, leading to greater precision, efficiency, and improved outcomes. Various studies across different disciplines have reported encouraging results using mixed reality technologies, such as augmented and virtual reality. To provide a better understanding of the applications and limitations of this technology in plastic surgery, we performed a systematic review of the literature in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The initial query of the National Center for Biotechnology Information database yielded 2544 results, and only 46 articles met our inclusion criteria. The majority of studies were in the field of craniofacial surgery, and uses of mixed reality included preoperative planning, intraoperative guides, and education of surgical trainees. A deeper understanding of mixed reality technologies may promote its integration and also help inspire new and creative applications in healthcare.

Adipose-Derived Tissue in the Treatment of Dermal Fibrosis: Antifibrotic Effects of Adipose-Derived Stem Cells.

Treatment of hypertrophic scars and other fibrotic skin conditions with autologous fat injections shows promising clinical results; however, the underlying mechanisms of its antifibrotic action have not been comprehensively studied. Adipose-derived stem cells, or stromal cell-derived factors, inherent components of the transplanted fat tissue, seem to be responsible for its therapeutic effects on difficult scars. The mechanisms by which this therapeutic effect takes place are diverse and are mostly mediated by paracrine signaling, which switches on various antifibrotic molecular pathways, modulates the activity of the central profibrotic transforming growth factor ß/Smad pathway, and normalizes functioning of fibroblasts and keratinocytes in the recipient site. Direct cell-to-cell communications and differentiation of cell types may also play a positive role in scar treatment, even though they have not been extensively studied in this context. A more thorough understanding of the fat tissue antifibrotic mechanisms of action will turn this treatment from an anecdotal remedy to a more controlled, timely administered technology.

Platelet-Rich Plasma, Adipose Tissue, and Scar Modulation.

Level of Evidence: 4.

Current concepts related to hypertrophic scarring in burn injuries.

Scarring following burn injury and its accompanying aesthetic and functional sequelae still pose major challenges. Hypertrophic scarring (HTS) can greatly impact patients' quality of life related to appearance, pain, pruritus and even loss of function of the injured body region. The identification of molecular events occurring in the evolution of the burn scar has increased our knowledge; however, this information has not yet translated into effective treatment modalities. Although many of the pathophysiologic pathways that bring about exaggerated scarring have been identified, certain nuances in burn scar formation are starting to be recognized. These include the effects of neurogenic inflammation, mechanotransduction, and the unique interactions of burn wound fluid with fat tissue in the deeper dermal layers, all of which may influence scarring outcome. Tension on the healing scar, pruritus, and pain all induce signaling pathways that ultimately result in increased collagen formation and myofibroblast phenotypic changes. Exposure of the fat domes in the deep dermis is associated with increased HTS, possibly on the basis of altered interaction of adipose-derived stem cells and the deep burn exudate. These pathophysiologic patterns related to stem cell-cytokine interactions, mechanotransduction, and neurogenic inflammation can provide new avenues of exploration for possible therapeutic interventions.

The Effects of Perioperative Tamoxifen Therapy on Microvascular Flap Complications in Transverse Rectus Abdominis Myocutaneous/Deep Inferior Epigastric Perforator Flap Breast Reconstruction.

BACKGROUND: Tamoxifen is an important adjunct therapy in breast cancer treatment; however, it has been implicated in increasing microvascular flap complications. Current recommendations on stopping tamoxifen are conflicting and do not address tamoxifen therapy that is continued perioperatively. The purpose of this study is to determine whether tamoxifen taken at the time of free transverse rectus abdominis myocutaneous (TRAM) and deep inferior epigastric perforator (DIEP) flap breast reconstruction affects thrombotic complication rates. METHODS: A retrospective review of microvascular breast reconstruction with TRAM/DIEP flaps over the last 20 years was carried out at a single institution. Patients were divided into 2 cohorts: those receiving tamoxifen at the time of reconstruction (tamoxifen cohort) and those not taking tamoxifen (control). Demographic information, procedural characteristics, and rates of microvascular flap complications were compared. RESULTS: Forty-three patients (56 flaps) received tamoxifen at the time of microvascular breast reconstruction, and 185 patients (267 flaps) did not. Patients in the tamoxifen cohort had a lower mean age of 48.9 years (P = 0.013). A greater percentage of patients in the tamoxifen cohort had preoperative radiation (P < 0.0001) and chemotherapy (P = 0.018) and underwent delayed reconstruction (P < 0.0001). There were no significant differences between the 2 cohorts with regard to flap complications including both arterial and venous thrombosis, flap failure, and other local flap complications. CONCLUSIONS: Patients receiving tamoxifen during TRAM/DIEP flap breast reconstruction did not have increased rates of flap thrombosis or failure; therefore, stopping tamoxifen prior to these procedures may not be necessary.

Preparation, Characterization, and Clinical Implications of Human Decellularized Adipose Tissue Extracellular Matrix (hDAM): A Comprehensive Review.

Fat grafting is commonly employed by plastic and reconstructive surgeons to address contour abnormalities and soft-tissue defects; however, because retention rates and thus volume filling effects are unpredictable, there is a search for new and innovative approaches. Initial studies on the use of human decellularized adipose tissue extracellular matrix (hDAM) show promise for its use not only in tissue engineering, but also in fat grafting. In this review, we examine and analyze the literature for the preparation, characterization, and use of hDAM and its derivatives in tissue engineering and plastic surgery applications. All studies reviewed involve physical, chemical, and/or biological treatment stages for the preparation of hDAM; however a distinction should be made between detergent and nondetergent-based processing, the latter of which appears to preserve the native integrity of the hDAM while most-efficiently achieving complete decellularization. Methods of hDAM characterization vary among groups and included simple and immunohistochemical staining, biochemical assays, 3-dimensional (3D) imaging, and mechano-stress testing, all of which are necessary to achieve a comprehensive description of this novel tissue. Finally, we examine the various preclinical models utilized to optimize hDAM performance, which primarily include the addition of adipose-derived stem cells or cross-linking agents. Overall, hDAM appears to be a promising adjunct in fat-grafting applications or even possibly as a stand-alone soft-tissue filler with off-the-shelf potential for commercial applications.

Implications for human adipose-derived stem cells in plastic surgery.

Adipose-derived stem cells (ADSCs) are a subset of mesenchymal stem cells (MSCs) that possess many of the same regenerative properties as other MSCs. However, the ubiquitous presence of ADSCs and their ease of access in human tissue have led to a burgeoning field of research. The plastic surgeon is uniquely positioned to harness this technology because of the relative frequency in which they perform procedures such as liposuction and autologous fat grafting. This review examines the current landscape of ADSC isolation and identification, summarizes the current applications of ADSCs in the field of plastic surgery, discusses the risks associated with their use, current barriers to universal clinical translatability, and surveys the latest research which may help to overcome these obstacles.

Evaluating visual perception for assessing reconstructed flap health.

BACKGROUND: Detecting failing tissue flaps before they are clinically apparent has the potential to improve postoperative flap management and salvage rates. This study demonstrates a model to quantitatively compare clinical appearance, as recorded via digital camera, with spatial frequency domain imaging (SFDI), a noninvasive imaging technique using patterned illumination to generate images of total hemoglobin and tissue oxygen saturation (stO2). METHODS: Using a swine pedicle model in which blood flow was carefully controlled with occlusion cuffs and monitored with ultrasound probes, throughput was reduced by 25%, 50%, 75%, and 100% of baseline values in either the artery or the vein of each of the flaps. The color changes recorded by a digital camera were quantified to predict which occlusion levels were visible to the human eye. SFDI was also used to quantify the changes in physiological parameters including total hemoglobin and oxygen saturation associated with each occlusion. RESULTS: There were no statistically significant changes in color above the noticeable perception levels associated with human vision during any of the occlusion levels. However, there were statistically significant changes in total hemoglobin and stO2 levels detected at the 50%, 75%, and 100% occlusion levels for arterial and venous occlusions. CONCLUSIONS: As demonstrated by the color imaging data, visual flap changes are difficult to detect until significant occlusion has occurred. SFDI is capable of detecting changes in total hemoglobin and stO2 as a result of partial occlusions before they are perceivable, thereby potentially improving response times and salvage rates.

Strategic sequences in fat graft survival.

Although lipotransfer, or fat grafting, is a commonly used procedure in aesthetic and reconstructive surgery, there is still variability in graft survival and neoadipogenesis from one procedure to the next. A better understanding of the sequential molecular events occurring with grafting would allow us to strategize methods to improve the regenerative potency of the grafted tissue. These steps begin with an autophagic process, followed by the inclusion of stromal vascular fraction and matrix components. By tailoring and modifying each of these steps for a particular type of aesthetic or reconstructive procedure, strategic sequencing represents a dynamic approach to lipotransfer with the aim of maximizing adipocyte viability and growth. In the implementation of the strategic sequence, it remains important to consider the clinical viability of each step and its compliance with the US Food and Drug Administration regulations. This review highlights the basic science behind clinically translatable approaches to supplementing various fat grafting procedures.

Single-lumen and multi-lumen poly(ethylene glycol) nerve conduits fabricated by stereolithography for peripheral nerve regeneration in vivo.

BACKGROUND: The use of nerve conduits to facilitate nerve regrowth after peripheral nerve injury is limited to defects less than 3 cm. The purpose of this study is to determine the capability of novel single and multi-lumen poly(ethylene glycol) (PEG) conduits manufactured by stereolithography to promote peripheral nerve regeneration. MATERIALS AND METHODS: Eight Sprague Dawley rats with sharp transection injuries of the sciatic nerve were randomly assigned to receive single-lumen or multi-lumen PEG conduits to bridge a 10-mm gap. Sciatic nerve and conduit samples were harvested after 5 weeks, and axon number, myelin thickness, fiber diameter, and g-ratio were analyzed. The contralateral intact nerve was also harvested for comparison. RESULTS: Partial nerve regeneration was observed in three out of four single-lumen conduits and one out of four multi-lumen conduits. Axon number in the single-lumen regenerated nerve approached that of the contralateral intact nerve at 4,492 ± 2,810.0 and 6,080 ± 627.9 fibers/mm(2), respectively. The percentage of small fibers was greater in the single-lumen conduit compared with the intact nerve, whereas myelin thickness and g-ratio were consistently greater in the autologous nerve. Axon regrowth through the multi-lumen conduits was severely limited. CONCLUSION: Single-lumen stereolithography-manufactured PEG nerve conduits promote nerve regeneration, with regenerating axon numbers approaching that of normal nerve. Multi-lumen conduits demonstrated significantly less nerve regeneration, possibly due to physical properties of the conduit inhibiting growth. Further studies are necessary to compare the efficacy of the two conduits for functional recovery and to elucidate the reasons underlying their differences in nerve regeneration potential.

The plantar fat pad and the diabetic foot--a review.

There has been much debate concerning the pathologic consequences of diabetes on the plantar fat pad and its subsequent association with the development of a foot ulcer. This review article documents two theories regarding pathophysiology in diabetic foot ulcer formation as they are related to the plantar fat pad and discusses current treatment options for this pathophysiological phenomenon. Traditionally, fat pad atrophy in diabetic patients was thought to result as an irregular arrangement of collagen fibrils within the septal walls as a result of glycation as well as diminishing adipocyte size due to thickened septal walls. Contrary to this traditional theory, a model depicting distal fat pad migration from under the metatarsal heads has been described in the diabetic patient. Such pad migration renders the metatarsal heads vulnerable to increased pressure, which, in turn, predisposes to foot ulceration. This migratory fat pad theory plays a significant role in approaches to the prevention of diabetic foot ulceration and subsequent amputation. Various methods of fat pad supplementation and claw toe management are impacted by the pathophysiological changes described and new avenues of therapy may be based on these changes.

Predictive risk factors of venous thromboembolism in autologous breast reconstruction surgery.

BACKGROUND: Venous thromboembolism (VTE) can be a significant cause of morbidity and mortality in autologous breast reconstruction surgery. The aim of this study was to evaluate the effect of patient characteristics, comorbidities, payer type, reconstruction type, reconstruction timing, radiation, chemotherapy, and teaching status of hospital on VTE (deep venous thrombosis and/or pulmonary embolism) in autologous breast reconstructive surgery. METHODS: Using the Nationwide Inpatient Sample (NIS) database, we examined the clinical data of patients who underwent autologous breast reconstructive surgery in 2009 to 2010 in the United States. Univariate and multivariate regression analyses were performed to identify factors predictive of in-hospital VTE. RESULTS: A total of 35,883 patients underwent autologous breast reconstructive surgery during this period. Overall rate of VTE was 0.13%. The highest rate of VTE (0.26%) was observed in pedicled transverse rectus abdominis myocutaneous flap. Patients who experienced VTE had significantly longer mean hospital stay (11.6 vs 3.9 days; P < 0.001) and higher mean total hospital charges ($146,432 vs $61,794; P < 0.001) compared with non-VTE patients; however, there was no significant difference observed in mortality rate (VTE, 0.0% vs non-VTE, 0.04%; P = 0.886). Using multivariate regression analysis, immediate reconstruction after mastectomy (adjusted odds ratio [AOR], 5.4), older than 65 years (AOR, 4.2), obesity (AOR, 3.7), history of chemotherapy (AOR, 3.5), and chronic lung disease (AOR, 2.5) were associated with higher risk of VTE. There was no association between race, payer type, diabetes, hypertension, liver disease, congestive heart failure, peripheral vascular disease, chronic kidney disease, smoking, reconstruction type, radiation, or teaching status of hospital on VTE. CONCLUSIONS: In patients undergoing autologous breast reconstruction surgery, immediate reconstruction, older than 65 years, obesity, history of chemotherapy, and chronic lung disease are all independent predictors of higher VTE. Surgeons should consider these factors and use appropriate prophylaxis to minimize the risk of VTE development.