Oral health care among patients with diabetes in Australia: A snapshot

Background

Diabetes increases the risk of periodontal disease, which in turn negatively impact on diabetes control and complications. Therefore, awareness about the diabetes-oral health link and dental problems is important for people with diabetes. This study aimed to assess self-reported oral health status and knowledge of people living with diabetes.

Methods

A survey was conducted among patients who attended four public diabetes clinics in Sydney, Australia. The questionnaire included 10 knowledge items and a validated Oral Health Impact Profile (OHIP-14) scale. A convenience sample of 200 patients were recruited. The data were analysed using SPSS software with descriptive and Pearson's Chi-Squared tests reported.

Results

The mean age of participants was 62.4(±13.5) years. More than half were males (54.5%), born overseas (64%), not working (73%) and had type 2 diabetes (88%). More than half (55.1%) of the patients reported having one or more dental problems and this was negatively associated with their oral health-related quality of life (p < 0.001). The most common dental problems were: gaps between teeth, pain in teeth and dry mouth. Only 46.2% of the participants had adequate oral health knowledge (> the mean correct score 5.2 (±2.6). The main areas with poor knowledge were around the impact of gum disease on blood glucose levels (29.6%), effects of dry mouth on tooth decay (33.8%) and the link between diabetes and teeth and gums (44.5%). Only 13% of the patients reported receiving oral health information from diabetes care providers (diabetes educator, general practitioner/diabetes specialist and dietitian/nutritionist). Receiving oral health information was found to be significantly associated with higher oral health knowledge scores (p < 0.05).

Conclusions

Considering that a majority of patients with diabetes have dental problems and inadequate oral health knowledge, diabetes care providers should take the opportunity to educate patients about oral health risks.

Key messages

People living with diabetes found to have dental problems and inadequate oral health knowledge. Considering that diabetes and dental problems adversely affect each other, it is crucial to educate patients about good oral hygiene and regular dental visit.

Reconstruction of digit planer injuries using component transfer of double second toes: A case report

The purpose of this report is to show that customized component second-toe transfers may improve functional and aesthetic outcomes following bone, soft tissue, and joint destruction of traumatically injured digits. A 22-year-old male sustained a planer injury resulting in loss of the distal volar soft tissues of the middle, ring, and small fingers, along with variable destruction of middle phalanges and distal interphalangeal joints. Simultaneous vascularized second-toe transfers were performed with customized joint and pulp reconstruction of middle and small fingers. The ring finger was salvaged using non-vascularized autologous bone graft and acellular dermal matrix. The patient had an uncomplicated postoperative course. Five-year strength, sensory and patient reported outcomes represent overall satisfactory results. Strength testing revealed the injured hand to perform within 90% strength of the uninjured side. Sensory outcomes showed present but diminished sensory perception in each of the injured digits. The patient's upper extremity function, physical health, quality of life, and foot health were overall acceptable, and he returned to using his hand for typing, writing, weight-lifting, and woodworking.

PHD-2 Suppression in Mesenchymal Stromal Cells Enhances Wound Healing

BACKGROUND

Cell therapy with mesenchymal stromal cells is a promising strategy for tissue repair. Restoration of blood flow to ischemic tissues is a key step in wound repair, and mesenchymal stromal cells have been shown to be proangiogenic. Angiogenesis is critically regulated by the hypoxia-inducible factor (HIF) superfamily, consisting of transcription factors targeted for degradation by prolyl hydroxylase domain (PHD)-2. The aim of this study was to enhance the proangiogenic capability of mesenchymal stromal cells and to use these modified cells to promote wound healing.

METHODS

Mesenchymal stromal cells harvested from mouse bone marrow were transduced with short hairpin RNA (shRNA) against PHD-2; control cells were transduced with scrambled shRNA (shScramble) construct. Gene expression quantification, human umbilical vein endothelial cell tube formation assays, and wound healing assays were used to assess the effect of PHD knockdown mesenchymal stromal cells on wound healing dynamics.

RESULTS

PHD-2 knockdown mesenchymal stromal cells overexpressed HIF-1α and multiple angiogenic factors compared to control (p < 0.05). Human umbilical vein endothelial cells treated with conditioned medium from PHD-2 knockdown mesenchymal stromal cells exhibited increased formation of capillary-like structures and enhanced migration compared with human umbilical vein endothelial cells treated with conditioned medium from shScramble-transduced mesenchymal stromal cells (p < 0.05). Wounds treated with PHD-2 knockdown mesenchymal stromal cells healed at a significantly accelerated rate compared with wounds treated with shScramble mesenchymal stromal cells (p < 0.05). Histologic studies revealed increased blood vessel density and increased cellularity in the wounds treated with PHD-2 knockdown mesenchymal stromal cells (p < 0.05).

CONCLUSIONS

Silencing PHD-2 in mesenchymal stromal cells augments their proangiogenic potential in wound healing therapy. This effect appears to be mediated by overexpression of HIF family transcription factors and up-regulation of multiple downstream angiogenic factors.

Proximalization of the Vascularized Toe Joint in Finger Proximal Interphalangeal Joint Reconstruction: A Technique to Derive Optimal Flexion From a Joint With Expected Limited Motion

When used to reconstruct a finger proximal interphalangeal joint, a free toe interphalangeal joint, without modification, cannot meet the motion demands of the finger to allow palm touchdown. This limitation is the direct result of the toe interphalangeal joint having an intrinsic arc of motion that delivers less flexion than that of a normal functioning finger proximal interphalangeal joint. By modifying the inset of the transferred joint to an extra-anatomical more proximal position, this limitation can be overcome. With a mathematical justification highlighted by a clinical illustration, we demonstrate the feasibility and utility of this "proximalization" technique.

Nonoperative Management of Acute Upper Limb Ischemia

BACKGROUND

Acute upper limb ischemia (AULI) is an uncommon emergency warranting immediate evaluation and treatment. The role of nonsurgical therapies including endovascular techniques, thrombolytics, and anticoagulation remains undefined. The authors systematically reviewed the current literature on the nonsurgical treatment of acute ischemia of the upper extremity.

METHODS

A PubMed and Embase search was conducted, and articles were screened using predetermined criteria. Data collected included patient demographics, cause of upper limb ischemia, type of nonsurgical treatment used, treatment outcomes, and complications. Patients were divided into 4 treatment groups: catheter embolectomy, catheter-directed thrombolysis, endovascular stenting, and anticoagulation/medical therapy alone.

RESULTS

Twenty-three retrospective studies met the search criteria. Of 1326 reported occlusions, 92% (1221) were attributed to thromboembolic disease. The second most common cause was iatrogenic (1.5%). Overall limb salvage rates were excellent with catheter embolectomy (862 of 882 cases, 97.7%) and catheter-directed thrombolysis (110 of 114 cases, 96.5%). Limb salvage rates were also high with anticoagulation/medical therapy (158 of 165 cases, 95.8%), but poor functional outcomes were more often reported.

CONCLUSIONS

High-quality evidence to guide the nonsurgical treatment of AULI is lacking. Retrospective studies support the utility of catheter-based embolectomy and thrombolysis for distal ischemia. Whether a surgical or nonsurgical approach is taken, anticoagulation therapy remains a mainstay of both treatment and prevention of AULI. Because AULI patients often have underlying cardiac and/or systemic disease, a multidisciplinary approach is essential to minimize complications and prevent future occurrences.

Knee Donor Site Morbidity Following Harvest of Medial Femoral Trochlea Osteochondral Flaps for Carpal Reconstruction

PURPOSE

This study examines donor site morbidity associated with the medial femoral trochlea (MFT) when used as a donor site for vascularized osteochondral flaps for reconstruction of challenging carpal defects such as proximal pole scaphoid nonunion and advanced Kienböck disease.

METHODS

The retrospective study population included all patients who had undergone MFT flap harvest for scaphoid or lunate reconstruction. Chart review, patient questionnaires, and validated knee function assessment tools were used: International Knee Documentation Committee Subjective Knee Form scores ranged from 0 (maximal disability) to 100 (no disability). Western Ontario and McMaster Universities osteoarthritis index scores ranged from 0% (no disability) to 100% (maximal disability). Magnetic resonance imaging and radiographs were obtained on the donor knee on the majority of patients.

RESULTS

Questionnaire response rate was 79% (45 of 57 patients). Average patient age was 35 ± 11 years (range, 19-70 years). Average postoperative follow-up was 27 ± 17 months (range, 9-108 months). The indication for MFT flap reconstruction was scaphoid nonunion in 30 patients and Kienböck disease in 15 patients. All 45 patients had a stable knee on examination. Magnetic resonance and radiographic imaging obtained on 35 patients exhibited no pathological changes. Average duration of postoperative pain was 56 ± 59 days (range, 0-360 days); average duration until patients reported the knee returning to normal was 90 ± 60 days (range, 14-360 days). Forty-three of 44 patients would have the same surgery again if needed; overall satisfaction with the surgery was rated as 5 ± 1 (range, 2-5) on a scale from 0 (no satisfaction) to 5 (maximal satisfaction). Average International Knee Documentation Committee score was 96 ± 9 (range, 56.3-100) and the average Western Ontario and McMaster Universities score was 6% ± 16% (range, 0%-68%).

CONCLUSIONS

Medial femoral trochlea osteochondral flap harvest results in minimal donor site morbidity in the majority of patients. Symptoms are time limited. Intermediate-term follow-up demonstrates excellent results in subjective outcome measures.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Multiple Subsets of Brain Tumor Initiating Cells Coexist in Glioblastoma

Brain tumor-initiating cells (BTICs) are self-renewing multipotent cells critical for tumor maintenance and growth. Using single-cell microfluidic profiling, we identified multiple subpopulations of BTICs coexisting in human glioblastoma, characterized by distinct surface marker expression and single-cell molecular profiles relating to divergent bulk tissue molecular subtypes. These data suggest BTIC subpopulation heterogeneity as an underlying source of intra-tumoral bulk tissue molecular heterogeneity, and will support future studies into BTIC subpopulation-specific therapies. Stem Cells 2016;34:1702-1707.

Challenges and Opportunities in Drug Delivery for Wound Healing

Significance: Chronic wounds remain a significant public health problem. Alterations in normal physiological processes caused by aging or diabetes lead to impaired tissue repair and the development of chronic and nonhealing wounds. Understanding the unique features of the wound environment will be required to develop new therapeutics that impact these disabling conditions. New drug-delivery systems (DDSs) may enhance current and future therapies for this challenging clinical problem. Recent Advances: Historically, physical barriers and biological degradation limited the efficacy of DDSs in wound healing. In aiming at improving and optimizing drug delivery, recent data suggest that combinations of delivery mechanisms, such as hydrogels, small molecules, RNA interference (RNAi), as well as growth factor and stem cell-based therapies (biologics), could offer exciting new opportunities for improving tissue repair. Critical Issues: The lack of effective therapeutic approaches to combat the significant disability associated with chronic wounds has become an area of increasing clinical concern. However, the unique challenges of the wound environment have limited the development of effective therapeutic options for clinical use. Future Directions: New platforms presented in this review may provide clinicians and scientists with an improved understanding of the alternatives for drug delivery in wound care, which may facilitate the development of new therapeutic approaches for patients.

Load-Dependent Emission Factors and Chemical Characteristics of IVOCs from a Medium-Duty Diesel Engine

A detailed understanding of the climate and air quality impacts of mobile-source emissions requires the characterization of intermediate-volatility organic compounds (IVOCs), relatively-low-vapor-pressure gas-phase species that may generate secondary organic aerosol with high yields. Due to challenges associated with IVOC detection and quantification, IVOC emissions remain poorly understood at present. Here, we describe measurements of the magnitude and composition of IVOC emissions from a medium-duty diesel engine. Measurements are made on an engine dynamometer and utilize a new mass-spectrometric instrument to characterize the load dependence of the emissions in near-real-time. Results from steady-state engine operation indicate that IVOC emissions are highly dependent on engine power, with highest emissions at engine idle and low-load operation (≤25% maximum rated power) with a chemical composition dominated by saturated hydrocarbon species. Results suggest that unburned fuel components are the dominant IVOCs emitted at low loads. As engine load increases, IVOC emissions decline rapidly and become increasingly characterized by unsaturated hydrocarbons and oxygenated organics, newly formed from incomplete combustion processes at elevated engine temperatures and pressures. Engine transients, including a cold-start ignition and engine acceleration, show IVOC emission profiles that are different in amount or composition compared to steady-state combustion, underscoring the utility of characterizing IVOC emissions with high time resolution across realistic engine operating conditions. We find possible evidence for IVOC losses on unheated dilution and sampling surfaces, which need to be carefully accounted for in IVOC emission studies.

Lateral Femoral Condyle Flap: An Alternative Source of Vascularized Bone From the Distal Femur

PURPOSE

To elucidate the vascular anatomy of the superolateral geniculate artery (SLGA) and its supply to the periosteum of the lateral femoral condyle (LFC) and to provide guidelines for flap design and describe an illustrative case.

METHODS

Thirty-one fresh cadaveric limbs were dissected. The vascular anatomy of the SLGA and its distal branches to skin, muscle, and periosteum were identified. Fluoroscopic images were taken during continuous perfusion of a radiopaque contrast dye into the SLGA. Intra-arterial injections of latex rubber were performed in 12 cadaver limbs. The vascular territory was traced from the SLGA to its distal branches, and surrounding soft tissues were dissected.

RESULTS

The SLGA originated from the popliteal artery 4.9 ± 1.2 cm (range, 2.8-7 cm) from the knee joint and its pedicle diameter was 1.8 ± 0.5 mm (range, 1-3 mm). SGLA pedicle-specific fluoroscopic angiography demonstrated a dense filigree of vessels over the lateral distal femur. Arterial latex injections confirmed that the SLGA supplied the periosteum of the LFC and distal femur shaft. The proximal-most extent of periosteal perfusion was 11.7 ± 2.1 cm (range, 9.3-14.1 cm) from the knee joint. The average pedicle length of LFC osteoperiosteal flaps was 4.8 ± 0.9 cm (range, 3.5-6.3 cm).

CONCLUSIONS

The LFC flap consistently demonstrated almost 12 cm of femur length perfusion based on the SLGA pedicle. The anatomy of this flap enables chimeric designs combining soft tissue, bone, and cartilage.

CLINICAL RELEVANCE

The vascularized LFC flap is an option for reconstruction of osseous defects of the upper extremity.

Common radiographic imaging modalities fail to accurately predict capitate morphology

BACKGROUND

There are three morphologies of the capitate based on its lunate and scaphoid articulations: flat, spherical, and V-shaped. Following a proximal row carpectomy (PRC), the capitate articulates with the lunate facet of the radius, altering contact biomechanics at the radiocarpal joint. Therefore, capitate morphology may influence contact pressures at the capitolunate articulation and influence clinical outcomes after PRC. However, it remains unclear which diagnostic imaging technique most reliably distinguishes between capitate morphologies.

METHODS

We evaluated the ability of plain radiographs, two-dimensional computed tomography (2D-CT), three-dimensional (3D)-CT reconstruction, and magnetic resonance imaging (MRI) to predict capitate type in 47 fresh frozen cadaver wrists. Two attending hand surgeons and one hand surgery fellow characterized capitate type based on each imaging modality. True capitate type was determined after gross dissection. We determined the reliability of each modality to predict capitate morphology.

RESULTS

We found all four imaging modalities to have a low sensitivity and specificity for predicting capitate morphology. Plain radiographs, 2D-CT, 3D-CT, and MRI had sensitivities/specificities of 0.46/0.57, 0.54/0.72, 0.54/0.52, and 0.56/0.65, respectively. All modalities had high negative predictive values for detecting the more rare V-shaped capitate subtype (range 91-94 %). Inter-rater reliability was poor for all modalities.

CONCLUSION

These data suggest that plain radiographs, CT, 3D-CT, and MRI are not helpful in preoperative determination of true capitate morphology. Plain radiographs are as effective as more cost-intensive modalities in ruling out V-shaped capitates.

Nanotechnology in bone tissue engineering

Nanotechnology represents a major frontier with potential to significantly advance the field of bone tissue engineering. Current limitations in regenerative strategies include impaired cellular proliferation and differentiation, insufficient mechanical strength of scaffolds, and inadequate production of extrinsic factors necessary for efficient osteogenesis. Here we review several major areas of research in nanotechnology with potential implications in bone regeneration: 1) nanoparticle-based methods for delivery of bioactive molecules, growth factors, and genetic material, 2) nanoparticle-mediated cell labeling and targeting, and 3) nano-based scaffold construction and modification to enhance physicochemical interactions, biocompatibility, mechanical stability, and cellular attachment/survival. As these technologies continue to evolve, ultimate translation to the clinical environment may allow for improved therapeutic outcomes in patients with large bone deficits and osteodegenerative diseases.

FROM THE CLINICAL EDITOR

Traditionally, the reconstruction of bony defects has relied on the use of bone grafts. With advances in nanotechnology, there has been significant development of synthetic biomaterials. In this article, the authors provided a comprehensive review on current research in nanoparticle-based therapies for bone tissue engineering, which should be useful reading for clinicians as well as researchers in this field.

Heterotopic Ossification: Basic-Science Principles and Clinical Correlates

➤ Heterotopic ossification occurs most commonly after joint arthroplasty, spinal cord injury, traumatic brain injury, blast trauma, elbow and acetabular fractures, and thermal injury.➤ The conversion of progenitor cells to osteogenic precursor cells as a result of cell-mediated interactions with the local tissue environment is affected by oxygen tension, pH, availability of micronutrients, and mechanical stimuli, and leads to heterotopic ossification.➤ Radiation and certain nonsteroidal anti-inflammatory medications are important methods of prophylaxis against heterotopic ossification.➤ Well-planned surgical excision can improve patient outcomes regardless of the joint involved or the initial cause of injury.➤ Future therapeutic strategies are focused on targeted inhibition of local factors and signaling pathways that catalyze ectopic bone formation.

Progenitor cell dysfunctions underlie some diabetic complications

Stem cells and progenitor cells are integral to tissue homeostasis and repair. They contribute to health through their ability to self-renew and commit to specialized effector cells. Recently, defects in a variety of progenitor cell populations have been described in both preclinical and human diabetes. These deficits affect multiple aspects of stem cell biology, including quiescence, renewal, and differentiation, as well as homing, cytokine production, and neovascularization, through mechanisms that are still unclear. More important, stem cell aberrations resulting from diabetes have direct implications on tissue function and seem to persist even after return to normoglycemia. Understanding how diabetes alters stem cell signaling and homeostasis is critical for understanding the complex pathophysiology of many diabetic complications. Moreover, the success of cell-based therapies will depend on a more comprehensive understanding of these deficiencies. This review has three goals: to analyze stem cell pathways dysregulated during diabetes, to highlight the effects of hyperglycemic memory on stem cells, and to define ways of using stem cell therapy to overcome diabetic complications.

Stem Cells in Wound Healing: The Future of Regenerative Medicine? A Mini-Review

The increased risk of disease and decreased capacity to respond to tissue insult in the setting of aging results from complex changes in homeostatic mechanisms, including the regulation of oxidative stress and cellular heterogeneity. In aged skin, the healing capacity is markedly diminished resulting in a high risk for chronic wounds. Stem cell-based therapies have the potential to enhance cutaneous regeneration, largely through trophic and paracrine activity. Candidate cell populations for therapeutic application include adult mesenchymal stem cells, embryonic stem cells and induced pluripotent stem cells. Autologous cell-based approaches are ideal to minimize immune rejection but may be limited by the declining cellular function associated with aging. One strategy to overcome age-related impairments in various stem cell populations is to identify and enrich with functionally superior stem cell subsets via single cell transcriptomics. Another approach is to optimize cell delivery to the harsh environment of aged wounds via scaffold-based cell applications to enhance engraftment and paracrine activity of therapeutic stem cells. In this review, we shed light on challenges and recent advances surrounding stem cell therapies for wound healing and discuss limitations for their clinical adoption.

Interpretation of upper extremity arteriography: vascular anatomy and pathology [corrected]

Understanding the utility and interpretation of upper extremity angiography is critical for the hand surgeon treating vaso-occlusive diseases of the hand. Although invasive and requiring the use of contrast dye, it remains the gold standard for imaging of the vascular system of the upper extremity. Angiography may detect numerous variants of the upper limb arterial system which may contribute to surgical pathology. Extensive vascular collateralization helps to maintain perfusion to the hand and facilitates reconstruction of the upper extremity. It is paramount to remember that angiography is a dynamic study and should represent a "flexible roadmap" for surgical reconstruction.

Transdermal deferoxamine prevents pressure-induced diabetic ulcers

There is a high mortality in patients with diabetes and severe pressure ulcers. For example, chronic pressure sores of the heels often lead to limb loss in diabetic patients. A major factor underlying this is reduced neovascularization caused by impaired activity of the transcription factor hypoxia inducible factor-1 alpha (HIF-1α). In diabetes, HIF-1α function is compromised by a high glucose-induced and reactive oxygen species-mediated modification of its coactivator p300, leading to impaired HIF-1α transactivation. We examined whether local enhancement of HIF-1α activity would improve diabetic wound healing and minimize the severity of diabetic ulcers. To improve HIF-1α activity we designed a transdermal drug delivery system (TDDS) containing the FDA-approved small molecule deferoxamine (DFO), an iron chelator that increases HIF-1α transactivation in diabetes by preventing iron-catalyzed reactive oxygen stress. Applying this TDDS to a pressure-induced ulcer model in diabetic mice, we found that transdermal delivery of DFO significantly improved wound healing. Unexpectedly, prophylactic application of this transdermal delivery system also prevented diabetic ulcer formation. DFO-treated wounds demonstrated increased collagen density, improved neovascularization, and reduction of free radical formation, leading to decreased cell death. These findings suggest that transdermal delivery of DFO provides a targeted means to both prevent ulcer formation and accelerate diabetic wound healing with the potential for rapid clinical translation.

Live fibroblast harvest reveals surface marker shift in vitro

Current methods for the isolation of fibroblasts require extended ex vivo manipulation in cell culture. As a consequence, prior studies investigating fibroblast biology may fail to adequately represent cellular phenotypes in vivo. To overcome this problem, we describe a detailed protocol for the isolation of fibroblasts from the dorsal dermis of adult mice that bypasses the need for cell culture, thereby preserving the physiological, transcriptional, and proteomic profiles of each cell. Using the described protocol we characterized the transcriptional programs and the surface expression of 176 CD markers in cultured versus uncultured fibroblasts. The differential expression patterns we observed highlight the importance of a live harvest for investigations of fibroblast biology.

Functional reconstruction of subtotal thumb metacarpal defect with a vascularized medial femoral condyle flap: case report

Devastating hand injuries require customized reconstructive strategies to maximize functional outcomes. We report a case of thumb metacarpal reconstruction using a vascularized medial femoral condyle osteocutaneous flap in the setting of nearly complete metacarpal loss. In addition to achieving the traditional goals of reconstructing thumb length and providing stability, the medial femoral condyle flap allowed motion at the carpometacarpal joint. The patient's hand function was further optimized by a component transfer of a proximally injured but distally preserved index finger to the amputated middle finger position. The patient regained satisfactory grip and thumb function with minimal donor site morbidity. This case highlights the role of both creative and established approaches to reconstruct composite tissues following devastating hand injury.

Organ-level tissue engineering using bioreactor systems and stem cells: implications for transplant surgery

Vascularized composite allotransplantation (VCA) enables surgeons to address complex problems that exceed the possibilities of traditional autologous reconstruction. However, logistical and immunologic challenges currently limit the widespread application of VCA. Recent breakthroughs in the field of stem cells and tissue engineering have direct implications for the advancement of VCA. Specifically, the use of bioreactors may prolong ex vivo allograft survival and enable allograft modulations that mitigate immunogenicity and enhance graft function. Additionally, novel approaches utilizing bioreactor systems for stem cell seeding of vascularized bioscaffolds provide a blueprint for the de novo generation of complex tissues. These promising bioreactor-based strategies have the potential to expand the reconstructive applications of VCA, and could one day allow the fabrication of customized complex tissue grafts.

Moisturizing different racial skin types

The skin is a complex organ involved in thermoregulation, gas exchange, protection against pathogens, and barrier function to maintain proper hydration. When dry, the ability for skin to execute these tasks becomes impaired. Dry skin affects almost everyone as we age, but it is also dependent on external factors, such as dry climate, colder temperatures, and repeated washing. In addition, increasing evidence has shown racial variability in the physiological properties of skin, which directly impacts water content of the stratum corneum and sensitivity to exogenously applied agents. A multitude of products have been developed to treat dry skin, and as a group, moisturizers have been designed to either impart or restore hydration in the stratum corneum. Given the large number of moisturizers presently available, depending on individual components, several different mechanisms may be employed to promote skin hydration. As there exists dramatic racial variability in skin properties, certain moisturizers may thus be more effective in some and less effective in others to treat the common condition of dry skin.

Mechanical offloading of incisional wounds is associated with transcriptional downregulation of inflammatory pathways in a large animal model

Cutaneous scarring is a major source of morbidity and current therapies to mitigate scar formation remain ineffective. Although wound fibrosis and inflammation are highly linked, only recently have mechanical forces been implicated in these pathways. Our group has developed a topical polymer device that significantly reduces post-injury scar formation via the manipulation of mechanical forces. Here we extend these studies to examine the genomewide transcriptional effects of mechanomodulation during scar formation using a validated large animal model, the red Duroc pig. We demonstrate that mechanical loading of incisional wounds upregulates expression of genes associated with inflammatory and fibrotic pathways, and that device-mediated offloading of these wounds reverses these effects. Validation studies are needed to clarify the clinical significance of these findings.

Mechanotransduction and fibrosis

Scarring and tissue fibrosis represent a significant source of morbidity in the United States. Despite considerable research focused on elucidating the mechanisms underlying cutaneous scar formation, effective clinical therapies are still in the early stages of development. A thorough understanding of the various signaling pathways involved is essential to formulate strategies to combat fibrosis and scarring. While initial efforts focused primarily on the biochemical mechanisms involved in scar formation, more recent research has revealed a central role for mechanical forces in modulating these pathways. Mechanotransduction, which refers to the mechanisms by which mechanical forces are converted to biochemical stimuli, has been closely linked to inflammation and fibrosis and is believed to play a critical role in scarring. This review provides an overview of our current understanding of the mechanisms underlying scar formation, with an emphasis on the relationship between mechanotransduction pathways and their therapeutic implications.

Paroxysmal nocturnal hemoglobinuria: a red clot syndrome

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired, nonmalignant disorder of hematopoietic stem cells characterized by hemolysis, diminished hematopoiesis, and thrombophilia. We describe a 65-year-old woman with known PNH and peripheral arterial disease who presented with critical limb ischemia and a nonhealing left foot ulcer. She underwent surgical bypass of a diffusely diseased left superficial femoral artery with autologous reversed saphenous vein graft. Her postoperative course was complicated by wound sepsis and PNH exacerbation with resultant graft thrombosis requiring an above-knee amputation. This case highlights several key concepts relevant to the management of vascular surgery patients with PNH: (1) their predisposition for arterial and venous thrombosis; (2) hypercoagulability despite standard anticoagulation regimens; (3) the role of eculizumab (a monoclonal antibody that inhibits complement activation used to treat PNH) in reducing thrombotic complications and hemolysis; and (4) complications associated with the immunosuppressive effects of eculizumab. We recommend careful monitoring of hemolysis and immunosuppression, aggressive anticoagulation, frequent graft surveillance, and early consultation with hematology.

Biological therapies for the treatment of cutaneous wounds: phase III and launched therapies

INTRODUCTION

Normal wound healing mechanisms can be overwhelmed in the setting of complex acute and chronic tissue injury. Biological therapies are designed to augment and/or restore the body's natural wound healing abilities. There are a variety of available and emerging technologies utilizing this approach that have demonstrated the ability to augment wound healing.

AREAS COVERED

In this review, the clinical data on launched and emerging biological therapies for wound healing applications are summarized. The methodologies discussed include biological skin equivalents, growth factors/small molecules and stem cell-based therapies.

EXPERT OPINION

While many products possess convincing clinical data demonstrating their efficacy in comparison to standard treatment options, more robust, controlled studies are needed to determine the relative value among established and emerging biological therapies. Future bioengineering and stem cell-based approaches are of particular interest due to the simultaneous correction of multiple deficiencies present in the nonhealing wound.

Wound healing: a paradigm for regeneration

Human skin is a remarkably plastic organ that sustains insult and injury throughout life. Its ability to expeditiously repair wounds is paramount to survival and is thought to be regulated by wound components such as differentiated cells, stem cells, cytokine networks, extracellular matrix, and mechanical forces. These intrinsic regenerative pathways are integrated across different skin compartments and are being elucidated on the cellular and molecular levels. Recent advances in bioengineering and nanotechnology have allowed researchers to manipulate these microenvironments in increasingly precise spatial and temporal scales, recapitulating key homeostatic cues that may drive regeneration. The ultimate goal is to translate these bench achievements into viable bedside therapies that address the growing global burden of acute and chronic wounds. In this review, we highlight current concepts in cutaneous wound repair and propose that many of these evolving paradigms may underlie regenerative processes across diverse organ systems.

A Mechanomodulatory Device to Minimize Incisional Scar Formation

OBJECTIVE

To mechanically control the wound environment and prevent cutaneous scar formation.

APPROACH

We subjected various material substrates to biomechanical testing to investigate their ability to modulate skin behavior. Combinations of elastomeric materials, adhesives, and strain applicators were evaluated to develop topical stress-shielding devices. Noninvasive imaging modalities were utilized to characterize anatomic site-specific differences in skin biomechanical properties in humans. The devices were tested in a validated large animal model of hypertrophic scarring. Phase I within-patient controlled clinical trials were conducted to confirm their safety and efficacy in scar reduction in patients undergoing abdominoplasty surgery.

RESULTS

Among the tested materials and device applicators, a polymer device was developed that effectively off-loaded high tension wounds and blocked pro-fibrotic pathways and excess scar formation in red Duroc swine. In humans, different anatomic sites exhibit unique biomechanical properties that may correlate with the propensity to form scars. In the clinical trial, utilization of this device significantly reduced incisional scar formation and improved scar appearance for up to 12 months compared with control incisions that underwent routine postoperative care.

INNOVATION

This is the first device that is able to precisely control the mechanical environment of incisional wounds and has been demonstrated in multiple clinical trials to significantly reduce scar formation after surgery.

CONCLUSION

Mechanomodulatory strategies to control the incisional wound environment can significantly reduce pathologic scarring and fibrosis after surgery.

The role of focal adhesion complexes in fibroblast mechanotransduction during scar formation

Historically, great efforts have been made to elucidate the biochemical pathways that direct the complex process of wound healing; however only recently has there been recognition of the importance that mechanical signals play in the process of tissue repair and scar formation. The body's physiologic response to injury involves a dynamic interplay between mechanical forces and biochemical cues which directs a cascade of signals leading ultimately to the formation of fibrotic scar. Fibroblasts are a highly mechanosensitive cell type and are also largely responsible for the generation of the fibrotic matrix during scar formation and are thus a critical player in the process of mechanotransduction during tissue repair. Mechanotransduction is initiated at the interface between the cell membrane and the extracellular matrix where mechanical signals are first translated into a biochemical response. Focal adhesions are dynamic multi-protein complexes through which the extracellular matrix links to the intracellular cytoskeleton. These focal adhesion complexes play an integral role in the propagation of this initial mechanical cue into an extensive network of biochemical signals leading to widespread downstream effects including the influx of inflammatory cells, stimulation of angiogenesis, keratinocyte migration, fibroblast proliferation and collagen synthesis. Increasing evidence has demonstrated the importance of the biomechanical milieu in healing wounds and suggests that an integrated approach to the discovery of targets to decrease scar formation may prove more clinically efficacious than previous purely biochemical strategies.

Enabling stem cell therapies for tissue repair: current and future challenges

Stem cells embody the tremendous potential of the human body to develop, grow, and repair throughout life. Understanding the biologic mechanisms that underlie stem cell-mediated tissue regeneration is key to harnessing this potential. Recent advances in molecular biology, genetic engineering, and material science have broadened our understanding of stem cells and helped bring them closer to widespread clinical application. Specifically, innovative approaches to optimize how stem cells are identified, isolated, grown, and utilized will help translate these advances into effective clinical therapies. Although there is growing interest in stem cells worldwide, this enthusiasm must be tempered by the fact that these treatments remain for the most part clinically unproven. Future challenges include refining the therapeutic manipulation of stem cells, validating these technologies in randomized clinical trials, and regulating the global expansion of regenerative stem cell therapies.

Soft tissue mechanotransduction in wound healing and fibrosis

Recent evidence suggests that mechanical forces can significantly impact the biologic response to injury. Integrated mechanical and chemical signaling networks have been discovered that enable physical cues to regulate disease processes such as pathologic scar formation. Distinct molecular mechanisms control how tensional forces influence wound healing and fibrosis. Conceptual frameworks to understand cutaneous repair have expanded beyond traditional cell-cytokine models to include dynamic interactions driven by mechanical force and the extracellular matrix. Strategies to manipulate these biomechanical signaling networks have tremendous therapeutic potential to reduce scar formation and promote skin regeneration.

Craniosynostosis: molecular pathways and future pharmacologic therapy

Craniosynostosis describes the premature fusion of one or more cranial sutures and can lead to dramatic manifestations in terms of appearance and functional impairment. Contemporary approaches for this condition are primarily surgical and are associated with considerable morbidity and mortality. The additional post-operative problems of suture refusion and bony relapse may also necessitate repeated surgeries with their own attendant risks. Therefore, a need exists to not only optimize current strategies but also to develop novel biological therapies which could obviate the need for surgery and potentially treat or even prevent premature suture fusion. Clinical studies of patients with syndromic craniosynostosis have provided some useful insights into the important signaling pathways and molecular events guiding suture fate. Furthermore, the highly conserved nature of craniofacial development between humans and other species have permitted more focused and step-wise elucidation of the molecular underpinnings of craniosynostosis. This review will describe the clinical manifestations of craniosynostosis, reflect on our understanding of syndromic and non-syndromic craniosynostoses and outline the different approaches that have been adopted in our laboratory and elsewhere to better understand the pathogenesis of premature suture fusion. Finally, we will assess to what extent our improved understanding of the pathogenesis of craniosynostosis, achieved through laboratory-based and clinical studies, have made the possibility of a non-surgical pharmacological approach both realistic and tangible.

Therapeutic potential of bone marrow-derived mesenchymal stem cells for cutaneous wound healing

Despite advances in wound care, many wounds never heal and become chronic problems that result in significant morbidity and mortality to the patient. Cellular therapy for cutaneous wounds has recently come under investigation as a potential treatment modality for impaired wound healing. Bone marrow-derived mesenchymal stem cells (MSCs) are a promising source of adult progenitor cells for cytotherapy as they are easy to isolate and expand and have been shown to differentiate into various cell lineages. Early studies have demonstrated that MSCs may enhance epithelialization, granulation tissue formation, and neovascularization resulting in accelerated wound closure. It is currently unclear if these effects are mediated through cellular differentiation or by secretion of cytokines and growth factors. This review discusses the proposed biological contributions of MSCs to cutaneous repair and their clinical potential in cell-based therapies.

Tissue engineering for the management of chronic wounds: current concepts and future perspectives

Chronic wounds constitute a significant and growing biomedical burden. With the increasing growth of populations prone to dysfunctional wound healing, there is an urgent and unmet need for novel strategies to both prevent and treat these complications. Tissue engineering offers the potential to create functional skin, and the synergistic efforts of biomedical engineers, material scientists, and molecular and cell biologists have yielded promising therapies for non-healing wounds. However, traditional paradigms for wound healing focus largely on the role of inflammatory cells and fail to incorporate more recent research highlighting the importance of stem cells and matrix dynamics in skin repair. Approaches to chronic wound healing centred on inflammation alone are inadequate to guide the development of regenerative medicine-based technologies. As the molecular pathways and biologic defects underlying non-healing wounds are further elucidated, multifaceted bioengineering systems must advance in parallel to exploit this knowledge. In this viewpoint essay, we highlight the current concepts in tissue engineering for chronic wounds and speculate on areas for future research in this increasingly interdisciplinary field.

Gestational diabetes mellitus in five ethnic groups: a comparison of their clinical characteristics

AIMS

The prevalence of gestational diabetes mellitus has been shown to vary between ethnic groups. The differences in the clinical characteristics and outcomes of women with gestational diabetes mellitus from various ethnic groups have not been clearly defined.

METHODS

A retrospective review of women with gestational diabetes mellitus from a single institution between 2007 and 2010 was conducted. The clinical profiles of women from five ethnic groups (South-East Asian, South Asian, Middle Eastern, Anglo-European and Pacific Islander) were documented, including the outcomes of their pregnancy.

RESULTS

In this cohort of 827 women from these five ethnic groups, South-East Asians had the lowest BMI, lowest fasting (yet highest 2-h) glucose level on 75-g glucose tolerance test, lowest need for insulin therapy and lowest rate of macrosomia. South Asians had the lowest parity but strongest family history of diabetes. Their offspring also had the lowest birthweight. Women from Pacific Islands had the highest parity, BMI, fasting glucose levels on 75-g glucose tolerance test, HbA(1c) (at diagnosis of gestational diabetes mellitus as well as at 36 weeks' gestation) and greatest need for insulin therapy. Their offspring also had the highest birthweights.

CONCLUSION

This study highlighted the significant differences in clinical characteristics of women with gestational diabetes mellitus among five ethnic groups. These differences may need to be considered in the management of gestational diabetes mellitus, especially in the interpretation of normality for pregnancy.

Focal adhesion kinase links mechanical force to skin fibrosis via inflammatory signaling

Exuberant fibroproliferation is a common complication after injury for reasons that are not well understood. One key component of wound repair that is often overlooked is mechanical force, which regulates cell-matrix interactions through intracellular focal adhesion components, including focal adhesion kinase (FAK). Here we report that FAK is activated after cutaneous injury and that this process is potentiated by mechanical loading. Fibroblast-specific FAK knockout mice have substantially less inflammation and fibrosis than control mice in a model of hypertrophic scar formation. We show that FAK acts through extracellular-related kinase (ERK) to mechanically trigger the secretion of monocyte chemoattractant protein-1 (MCP-1, also known as CCL2), a potent chemokine that is linked to human fibrotic disorders. Similarly, MCP-1 knockout mice form minimal scars, indicating that inflammatory chemokine pathways are a major mechanism by which FAK mechanotransduction induces fibrosis. Small-molecule inhibition of FAK blocks these effects in human cells and reduces scar formation in vivo through attenuated MCP-1 signaling and inflammatory cell recruitment. These findings collectively indicate that physical force regulates fibrosis through inflammatory FAK-ERK-MCP-1 pathways and that molecular strategies targeting FAK can effectively uncouple mechanical force from pathologic scar formation.

Pullulan hydrogels improve mesenchymal stem cell delivery into high-oxidative-stress wounds

Cell-based therapies for wound repair are limited by inefficient delivery systems that fail to protect cells from the acute inflammatory environment. Here, a biomimetic hydrogel system is described that is based on the polymer pullulan, a carbohydrate glucan known to exhibit potent antioxidant capabilities. It is shown that pullulan hydrogels are an effective cell delivery system and improve mesenchymal stem cell survival and engraftment in high-oxidative-stress environments. The results suggest that glucan hydrogel systems may prove beneficial for progenitor-cell-based approaches to skin regeneration.

Enhancement of mesenchymal stem cell angiogenic capacity and stemness by a biomimetic hydrogel scaffold

In this study, we examined the capacity of a biomimetic pullulan-collagen hydrogel to create a functional biomaterial-based stem cell niche for the delivery of mesenchymal stem cells (MSCs) into wounds. Murine bone marrow-derived MSCs were seeded into hydrogels and compared to MSCs grown in standard culture conditions. Hydrogels induced MSC secretion of angiogenic cytokines and expression of transcription factors associated with maintenance of pluripotency and self-renewal (Oct4, Sox2, Klf4) when compared to MSCs grown in standard conditions. An excisonal wound healing model was used to compare the ability of MSC-hydrogel constructs versus MSC injection alone to accelerate wound healing. Injection of MSCs did not significantly improve time to wound closure. In contrast, wounds treated with MSC-seeded hydrogels showed significantly accelerated healing and a return of skin appendages. Bioluminescence imaging and FACS analysis of luciferase+/GFP+ MSCs indicated that stem cells delivered within the hydrogel remained viable longer and demonstrated enhanced engraftment efficiency than those delivered via injection. Engrafted MSCs were found to differentiate into fibroblasts, pericytes and endothelial cells but did not contribute to the epidermis. Wounds treated with MSC-seeded hydrogels demonstrated significantly enhanced angiogenesis, which was associated with increased levels of VEGF and other angiogenic cytokines within the wounds. Our data suggest that biomimetic hydrogels provide a functional niche capable of augmenting MSC regenerative potential and enhancing wound healing.

Palatogenesis: engineering, pathways and pathologies

Cleft palate represents the second most common birth defect and carries substantial physiologic and social challenges for affected patients, as they often require multiple surgical interventions during their lifetime. A number of genes have been identified to be associated with the cleft palate phenotype, but etiology in the majority of cases remains elusive. In order to better understand cleft palate and both surgical and potential tissue engineering approaches for repair, we have performed an in-depth literature review into cleft palate development in humans and mice, as well as into molecular pathways underlying these pathologic developments. We summarize the multitude of pathways underlying cleft palate development, with the transforming growth factor beta superfamily being the most commonly studied. Furthermore, while the majority of cleft palate studies are performed using a mouse model, studies focusing on tissue engineering have also focused heavily on mouse models. A paucity of human randomized controlled studies exists for cleft palate repair, and so far, tissue engineering approaches are limited. In this review, we discuss the development of the palate, explain the basic science behind normal and pathologic palate development in humans as well as mouse models and elaborate on how these studies may lead to future advances in palatal tissue engineering and cleft palate treatments.

Mechanical force prolongs acute inflammation via T-cell-dependent pathways during scar formation

Mechanical force significantly modulates both inflammation and fibrosis, yet the fundamental mechanisms that regulate these interactions remain poorly understood. Here we performed microarray analysis to compare gene expression in mechanically loaded wounds vs. unloaded control wounds in an established murine hypertrophic scar (HTS) model. We identified 853 mechanically regulated genes (false discovery rate <2) at d 14 postinjury, a subset of which were enriched for T-cell-regulated pathways. To substantiate the role of T cells in scar mechanotransduction, we applied the HTS model to T-cell-deficient mice and wild-type mice. We found that scar formation in T-cell-deficient mice was reduced by almost 9-fold (P < 0.001) with attenuated epidermal (by 2.6-fold, P < 0.01) and dermal (3.9-fold, P < 0.05) proliferation. Mechanical stimulation was highly associated with sustained T-cell-dependent Th2 cytokine (IL-4 and IL-13) and chemokine (MCP-1) signaling. Further, T-cell-deficient mice failed to recruit systemic inflammatory cells such as macrophages or monocytic fibroblast precursors in response to mechanical loading. These findings indicate that T-cell-regulated fibrogenic pathways are highly mechanoresponsive and suggest that mechanical forces induce a chronic-like inflammatory state through immune-dependent activation of both local and systemic cell populations.