Increased susceptibility to ischemia causes exacerbated response to microinjuries in the cirrhotic liver

Fractional laser ablation is a technique developed in dermatology to induce remodeling of skin scars by creating a dense pattern of microinjuries. Despite remarkable clinical results, this technique has yet to be tested for scars in other tissues. As a first step toward determining the suitability of this technique, we aimed to (1) characterize the response to microinjuries in the healthy and cirrhotic liver, and (2) determine the underlying cause for any differences in response. Healthy and cirrhotic rats were treated with a fractional laser then euthanized from 0 h up to 14 days after treatment. Differential expression was assessed using RNAseq with a difference-in-differences model. Spatial maps of tissue oxygenation were acquired with hyperspectral imaging and disruptions in blood supply were assessed with tomato lectin perfusion. Healthy rats showed little damage beyond the initial microinjury and healed completely by 7 days without scarring. In cirrhotic rats, hepatocytes surrounding microinjury sites died 4-6 h after ablation, resulting in enlarged and heterogeneous zones of cell death. Hepatocytes near blood vessels were spared, particularly near the highly vascularized septa. Gene sets related to ischemia and angiogenesis were enriched at 4 h. Laser-treated regions had reduced oxygen saturation and broadly disrupted perfusion of nodule microvasculature, which matched the zones of cell death. Our results demonstrate that the cirrhotic liver has an exacerbated response to microinjuries and increased susceptibility to ischemia from microvascular damage, likely related to the vascular derangements that occur during cirrhosis development. Modifications to the fractional laser tool, such as using a femtosecond laser or reducing the spot size, may be able to prevent large disruptions of perfusion and enable further development of a laser-induced microinjury treatment for cirrhosis.

The Yucatan miniature swine as a model for post-inflammatory hyperpigmentation

Post-inflammatory hyperpigmentation (PIH) is a hypermelanosis that often occurs secondary to skin irritation or injury, especially in darker skin tones, for which there is currently a lack of effective treatment options. Few preclinical models are available to study PIH. Here, we show that the Yucatan miniature pig consistently develops PIH after skin injuries. Skin wounds were produced on Yucatan pigs by needle punches, full-thickness excisions, or burns. Wound sites were monitored and photographed regularly. Tissue samples were collected after 24 weeks and processed for histology/immunohistochemistry. Skin pigmentation and histologic changes were quantified by computer-assisted image analyses. All injury methods resulted in hyperpigmentation. Melanin content at the histologic level was quantified in the larger (burn and excision) wounds, showing a significant increase compared to uninjured skin. Increased melanin was found for both epidermal and dermal regions. Dermal melanin deposits were primarily clustered around the papillary vasculature, and were associated not with melanocytes but with leukocytes. The Yucatan miniature pig model recapitulates key clinical and histologic features of PIH in humans, including skin hyperpigmentation at both gross and histologic levels, and persistence of dermal melanin subsequent to injury. This model could be used to further our understanding of the etiology of PIH, and for new therapy development.

Creation and Implementation of an Interdisciplinary Workflow for CBCT-Based Online Adaptive Radiotherapy

PURPOSE/OBJECTIVE(S)

CBCT-based online adaptive radiotherapy (OART) is an emerging treatment strategy to replan based on the anatomy of the day while the patient remains on the couch. OART is not just an add-on to the current workflow; it necessitates a new approach across the patient's path of care, from CT simulation to treatment delivery. OART requires the addition of duties to clinical personnel, strategies to create auto-plan templates, and monitoring the "black box" adaptation process. Studies have shown that OART implementation is limited by its resource-intensive nature and the risks associated with the treatment approach. We hypothesized that the implementation of an interdisciplinary, streamlined workflow and checklists would enhance the OART treatment efficiency, prevent medical errors from the adaptation, and minimize the burden on clinicians.

MATERIALS/METHODS

An interdisciplinary OART working group comprising radiation oncologists, medical physicists, dosimetrists, and therapists was created to enable weekly knowledge sharing, workflow design, implementation, and continuous process improvement. 213 adaptive sessions from 5 treatment sites (pancreas, bladder, prostate, rectum, anus) were treated on a CBCT-based OART platform in a single institutional study. An evaluation of the treatment safety and workflow time was performed for each adaptive session.

RESULTS

The OART workflow was divided into four sub-workflows: 1) pre-treatment site-specific template preparation, 2) pre-treatment initial planning and verification, 3) on-treatment procedure, and 4) post-treatment evaluation. The sub-processes involved 4, 8, 13, and 4 separate, sequentially tasks, respectively, and a total of 11 task checklists. The template preparation is a new process developed for site-specific, standardized physician template directives, automated planning template development, and testing for its accuracy and robustness. The planning templates generated high-quality initial plans automatically within minutes once structures were segmented on the planning CT. This process was replicated during treatment using the CBCT. The median (interquartile range) online procedure time, defined as the time from initial CBCT to plan approval, of the five treatment sites (pancreas, bladder, prostate, rectum, anus) was 22.1 (19.2-24.8) min, 16.5 (15.3-17.5) min, 14.7 (13.9-17.4) min, 17 (15.3-19.7) min, and 24 (21.4-25.8) min, respectively. Safety assessment determined that no treatment deviations were observed.

CONCLUSION

Creating an interdisciplinary, standardized workflow and checklists allowed the safe delivery of OART with clinically feasible online procedure time and significantly reduced initial planning time compared with traditional EBRT. The unique workflow is essential to minimize the burden on the care team, increase patient safety, and access to OART.

An antimicrobial blue light device to manage infection at the skin-implant interface of percutaneous osseointegrated implants

Antimicrobial blue light (aBL) is an attractive option for managing biofilm burden at the skin-implant interface of percutaneous osseointegrated (OI) implants. However, marketed aBL devices have both structural and optical limitations that prevent them from being used in an OI implant environment. They must be handheld, preventing even irradiation of the entire skin-implant interface, and the devices do not offer sufficient optical power outputs required to kill biofilms. We present the developmental process of a unique aBL device that overcomes these limitations. Four prototypes are detailed, each being a progressive improvement from the previous iteration as we move from proof-of-concept to in vivo application. Design features focused on a cooling system, LED orientation, modularity, and "sheep-proofing". The final prototype was tested in an in vivo OI implant sheep model, demonstrating that it was structurally and optically adequate to address biofilm burdens at the skin-implant of percutaneous OI implants. The device made it possible to test aBL in the unique OI implant environment and compare its efficacy to clinical antibiotics-data which had not before been achievable. It has provided insight into whether or not continued pursual of light therapy research for OI implants, and other percutaneous devices, is worthwhile. However, the device has drawbacks concerning the cooling system, complexity, and size if it is to be translated to human clinical trials. Overall, we successfully developed a device to test aBL therapy for patients with OI implants and helped progress understanding in the field of infection management strategies.

Energetic Electron Precipitation Driven by Electromagnetic Ion Cyclotron Waves from ELFIN's Low Altitude Perspective

We review comprehensive observations of electromagnetic ion cyclotron (EMIC) wave-driven energetic electron precipitation using data collected by the energetic electron detector on the Electron Losses and Fields InvestigatioN (ELFIN) mission, two polar-orbiting low-altitude spinning CubeSats, measuring 50-5000 keV electrons with good pitch-angle and energy resolution. EMIC wave-driven precipitation exhibits a distinct signature in energy-spectrograms of the precipitating-to-trapped flux ratio: peaks at >0.5 MeV which are abrupt (bursty) (lasting ∼17 s, or Δ L ∼ 0.56 ) with significant substructure (occasionally down to sub-second timescale). We attribute the bursty nature of the precipitation to the spatial extent and structuredness of the wave field at the equator. Multiple ELFIN passes over the same MLT sector allow us to study the spatial and temporal evolution of the EMIC wave - electron interaction region. Case studies employing conjugate ground-based or equatorial observations of the EMIC waves reveal that the energy of moderate and strong precipitation at ELFIN approximately agrees with theoretical expectations for cyclotron resonant interactions in a cold plasma. Using multiple years of ELFIN data uniformly distributed in local time, we assemble a statistical database of ∼50 events of strong EMIC wave-driven precipitation. Most reside at L ∼ 5 - 7 at dusk, while a smaller subset exists at L ∼ 8 - 12 at post-midnight. The energies of the peak-precipitation ratio and of the half-peak precipitation ratio (our proxy for the minimum resonance energy) exhibit an L -shell dependence in good agreement with theoretical estimates based on prior statistical observations of EMIC wave power spectra. The precipitation ratio's spectral shape for the most intense events has an exponential falloff away from the peak (i.e., on either side of ∼ 1.45 MeV). It too agrees well with quasi-linear diffusion theory based on prior statistics of wave spectra. It should be noted though that this diffusive treatment likely includes effects from nonlinear resonant interactions (especially at high energies) and nonresonant effects from sharp wave packet edges (at low energies). Sub-MeV electron precipitation observed concurrently with strong EMIC wave-driven >1 MeV precipitation has a spectral shape that is consistent with efficient pitch-angle scattering down to ∼ 200-300 keV by much less intense higher frequency EMIC waves at dusk (where such waves are most frequent). At ∼100 keV, whistler-mode chorus may be implicated in concurrent precipitation. These results confirm the critical role of EMIC waves in driving relativistic electron losses. Nonlinear effects may abound and require further investigation.

Comparison of Staphylococcus aureus tolerance between antimicrobial blue light, levofloxacin, and rifampin

Background

Bacterial biofilms readily develop on all medical implants, including percutaneous osseointegrated (OI) implants. With the growing rate of antibiotic resistance, exploring alternative options for managing biofilm-related infections is necessary. Antimicrobial blue light (aBL) is a unique therapy that can potentially manage biofilm-related infections at the skin-implant interface of OI implants. Antibiotics are known to have antimicrobial efficacy disparities between the planktonic and biofilm bacterial phenotypes, but it is unknown if this characteristic also pertains to aBL. In response, we developed experiments to explore this aspect of aBL therapy.

Methods

We determined minimum bactericidal concentrations (MBCs) and antibiofilm efficacies for aBL, levofloxacin, and rifampin against Staphylococcus aureus ATCC 6538 planktonic and biofilm bacteria. Using student t-tests (p < 0.05), we compared the efficacy profiles between the planktonic and biofilm states for the three independent treatments and a levofloxacin + rifampin combination. Additionally, we compared antimicrobial efficacy patterns for levofloxacin and aBL against biofilms as dosages increased.

Results

aBL had the most significant efficacy disparity between the planktonic and biofilm phenotypes (a 2.5 log₁₀ unit difference). However, further testing against biofilms revealed that aBL had a positive correlation between increasing efficacy and exposure time, while levofloxacin encountered a plateau. While aBL efficacy was affected the most by the biofilm phenotype, its antimicrobial efficacy did not reach a maximum.

Discussion/conclusion

We determined that phenotype is an important characteristic to consider when determining aBL parameters for treating OI implant infections. Future research would benefit from expanding these findings against clinical S. aureus isolates and other bacterial strains, as well as the safety of long aBL exposures on human cells.

Antimicrobial blue light as a biofilm management therapy at the skin-implant interface in an ex vivo percutaneous osseointegrated implant model

Biofilm contamination is often present at the skin-implant interface of transfemoral osseointegrated implants leading to frequent infection, irritation, and discomfort. New biofilm management regimens are needed as the current standard of washing the site with soap and water is inadequate to manage infection rates. We investigated the potential of antimicrobial blue light, which has reduced risk of resistance development and broad antimicrobial mechanisms. Our lab developed an antimicrobial blue light (aBL) device uniquely designed for an ex vivo system based on an established ovine osseointegrated (OI) implant model with Staphylococcus aureus ATCC 6538 biofilms as initial inocula. Samples were irradiated with aBL or washed for three consecutive days after which they were quantified. Colony-forming unit (CFU) counts were compared with a control group (bacterial inocula without treatment). After 1 day, aBL administered as a single 6 h dose or two 1 h doses spaced 6 h apart both reduced the CFU count by 1.63 log₁₀  ± 0.02 CFU. Over 3 days of treatment, a positive aBL trend was observed with a maximum reduction of ~2.7 log₁₀ CFU following 6 h of treatment, indicating a relation between multiple days of irradiation and greater CFU reductions. aBL was more effective at reducing the biofilm burden at the skin-implant interface compared with the wash group, demonstrating the potential of aBL as a biofilm management option.

Boot camp: Training and dressing regimens for modeling plantar wounds in the swine

Foot ulceration annually affects millions of patients and accounts for billions of dollars in medical expenses in the US alone. Many previous studies have investigated co-morbidities associated with impaired healing, such as microbial infection, compromised circulation, and diabetes. By comparison, little is known about how wound healing proceeds in plantar skin, despite its many unique specializations related to its load-bearing function. One of the main challenges in modeling plantar wounds is the difficulty in maintaining wound dressings, as animals generally have a low tolerance to wearing bandages on their feet. With assistance from the MGH Center for Comparative Medicine, we developed a positive reinforcement-based behavioral training regimen that successfully induced tolerance for plantar dressings in swine, which is a critical first step towards enabling in vivo study of the wound healing process in this highly specialized skin area. This training program will be described in detail in this manuscript.

The case for considering volar skin in a "separate status" for wound healing

Foot ulcers, particularly in the diabetic setting, are a major medical and socioeconomic challenge. While the effects of diabetes and its various sequelae have been extensively studied, in the wound field it is commonly assumed that the wound healing process is essentially identical between different skin types, despite the many well-known specializations in palmoplantar skin, most of which are presumed to be evolutionary adaptations for weightbearing. This article will examine how these specializations could alter the wound healing trajectory and contribute to the pathology of foot ulcers.

Local vasoregulative interventions impact drug concentrations in the skin after topical laser-assisted delivery

INTRODUCTION

The ability of ablative fractional lasers (AFL) to enhance topical drug uptake is well established. After AFL delivery, however, drug clearance by local vasculature is poorly understood. Modifications in vascular clearance may enhance AFL-assisted drug concentrations and prolong drug dwell time in the skin. Aiming to assess the role and modifiability of vascular clearance after AFL-assisted delivery, this study examined the impact of vasoregulative interventions on AFL-assisted 5-fluorouracil (5-FU) concentrations in in vivo skin.

METHODS

5-FU uptake was assessed in intact and AFL-exposed skin in a live pig model. After fractional CO₂ laser exposure (15 mJ/microbeam, 5% density), vasoregulative intervention using topical brimonidine cream, epinephrine solution, or pulsed dye laser (PDL) was performed in designated treatment areas, followed by a single 5% 5-FU cream application. At 0, 1, 4, 48, and 72 h, 5-FU concentrations were measured in 500 and 1500 μm skin layers by mass spectrometry (n = 6). A supplemental assessment of blood flow following AFL ± vasoregulation was performed using optical coherence tomography (OCT) in a human volunteer.

RESULTS

Compared to intact skin, AFL facilitated a prompt peak in 5-FU delivery that remained elevated up to 4 hours (1500 μm: 1.5 vs. 31.8 ng/ml [1 hour, p = 0.002]; 5.3 vs. 14.5 ng/ml [4 hours, p = 0.039]). However, AFL's impact was transient, with 5-FU concentrations comparable to intact skin at later time points. Overall, vasoregulative intervention with brimonidine or PDL led to significantly higher peak 5-FU concentrations, prolonging the drug's dwell time in the skin versus AFL delivery alone. As such, brimonidine and PDL led to twofold higher 5-FU concentrations than AFL alone in both skin layers by 1 hour (e.g., 500 μm: 107 ng/ml [brimonidine]; 96.9 ng/ml [PDL], 46.6 ng/ml [AFL alone], p ≤ 0.024), and remained significantly elevated at 4 hours (p ≤ 0.024). A similar pattern was observed for epinephrine, although trends remained nonsignificant (p ≥ 0.09). Prolonged 5-FU delivery was provided by PDL, resulting in sustained drug deposition compared to AFL alone at both 48 and 72 hours in the superficial skin layer (p ≤ 0.024). Supporting drug delivery findings, OCT revealed that increases in local blood flow after AFL were mitigated in test areas also exposed to PDL, brimonidine, or epinephrine, with PDL providing the greatest, sustained reduction in flow over 48 hours.

CONCLUSION

Vasoregulative intervention in conjunction with AFL-assisted delivery enhances and prolongs 5-FU deposition in in vivo skin.

Research protocol to evaluate the effectiveness of shockwave therapy, photobiomodulation and physical therapy in the management of non-insertional Achilles tendinopathy in runners: a randomised control trial with elective cross-over design

Background

Achilles tendinopathy (AT) is a common overuse injury in runners. While the mainstay of treatment for AT is tendon loading exercises (physical therapy and exercise programme (EXER)), some patients have refractory symptoms. Extracorporeal shockwave therapy (ESWT) and photobiomodulation therapy (PBMT) have each been evaluated to facilitate tendon healing; the influence of combining treatments is unknown and limited studies have been completed in runners. This randomised control study, with an elective cross-over at 3 months, will evaluate the efficacy of three forms of treatment of non-insertional AT: (1) EXER (loading programme specific to Achilles tendon combined with physical therapy); (2) EXER and ESWT; (3) EXER, ESWT and PBMT. Sixty runners will be assigned using block randomisation into one of three treatment groups (n=20). After 3 months, each participant may elect a different treatment than previously assigned and will be followed for an additional 3 months. The EXER Achilles loading programme will be standardised using the Silbernagel at-home programme. The primary outcome of interest is treatment group responses using the Victorian Institute of Sports Assessment—Achilles (VISA-A) Score. Secondary outcomes include the Patient-Reported Outcomes Measurement Information System—29 questions, the University of Wisconsin Running Injury and Recovery Index, heel raise to fatigue test, hopping test and ultrasound measurements. We will also capture patient preference and satisfaction with treatment. We hypothesise that the cohorts assigned EXER+ESWT+PBMT and EXER+ESWT will see greater improvements in VISA-A than the EXER cohort, and the largest gains are anticipated in combining ESWT+PBMT. The elective cross-over phase will be an exploratory study and will inform us whether patient preference for treatment will impact the treatment response.

Trial registration number

NCT04725513.

Laser Immunotherapy: A Potential Treatment Modality for Keratinocyte Carcinoma

Simple Summary

In light of expanding incidences of keratinocyte carcinoma (KC) with many patients developing multiple tumors, the demand for new treatment modalities is high. With the approval of cemplimab for locally advanced and metastasizing basal cell carcinoma and squamous cell carcinoma, KC is now included as an indication for systemic immunotherapy. At present, however, systemic KC therapy remains limited by the severe side effects associated with treatment. Immunotherapy might be more broadly applied if locally administered. Localized to the skin, KCs are easily accessible to topical drugs and physical interventions such as laser. There is an increasing appreciation of lasers’ potential to activate an immune response. Further enhancement of the laser-based immune activation might be obtained by combining laser and immunotherapeutic agents, known as laser immunotherapy. In search of new treatment modalities for KC and aiming to broaden the field of KC immunotherapy, this review discusses the current literature on immune activation following both laser monotherapy and laser immunotherapy.

Abstract

The role of the immune system in cancer growth is well recognized and the development of immunotherapy represents a breakthrough in cancer treatment. Recently, the use of systemic immunotherapy was extended to keratinocyte carcinoma (KC), specifically locally advanced and metastasizing basal and squamous cell carcinoma. However, since most KC lesions are non-aggressive, systemic treatment with associated side effects is rarely justified. Conversely, topical immunotherapy with imiquimod remains restricted to premalignant and superficial lesions. Use of laser in the treatment of KC has evolved from physical tumor destruction and laser-assisted drug delivery to laser-mediated immune modulation. Evidence indicates that laser monotherapy can lead to immune cell infiltration, tumor reduction and resistance to tumor re-inoculation. Combining laser with immunotherapeutic agents, termed laser immunotherapy (LIT), may further potentiate immune activation and tumor response. Studies on LIT show not only direct anti-tumor effects but systemic adaptive immunity, illustrated by the prevention of tumor recurrence and regression in distant untreated tumors. These findings imply a therapeutic potential for both local and metastatic disease. This work provides rationales for immune-based treatment of KC and presents the current status of KC immunotherapy. Aiming to expand the field of KC immunotherapy, the review discusses the literature on immune activation following laser monotherapy and LIT.

MagneTEskin-Reconstructing skin by magnetically induced assembly of autologous microtissue cores

Skin wounds are immense medical and socioeconomic burdens, and autologous skin grafting remains the gold standard for wound repair. We recently found that full-thickness micro skin tissue columns (MSTCs) can be harvested with minimal donor site morbidity, and that MSTCs applied to wounds “randomly” (without maintaining their natural epidermal-dermal orientation) can accelerate re-epithelialization. However, despite MSTCs containing all the cellular and extracellular contents of full-thickness skin, normal dermal architecture was not restored by random MSTCs. In this study, we developed a magnetically induced assembly method to produce constructs of densely packed, oriented MSTCs that closely resemble the overall architecture of full-thickness skin to test the hypothesis that maintaining MSTCs’ orientation could further hasten healing and restore a normal dermis. Our method led to faster and more orderly re-epithelialization but unexpectedly did not improve the retention of dermal architecture, which reveals a hitherto unappreciated role for tissue morphology in determining dermal remodeling outcomes.

Counteracting age-related VEGF signaling insufficiency promotes healthy aging and extends life span

Aging is an established risk factor for vascular diseases, but vascular aging itself may contribute to the progressive deterioration of organ function. Here, we show in aged mice that vascular endothelial growth factor (VEGF) signaling insufficiency, which is caused by increased production of decoy receptors, may drive physiological aging across multiple organ systems. Increasing VEGF signaling prevented age-associated capillary loss, improved organ perfusion and function, and extended life span. Healthier aging was evidenced by favorable metabolism and body composition and amelioration of aging-associated pathologies including hepatic steatosis, sarcopenia, osteoporosis, "inflammaging" (age-related multiorgan chronic inflammation), and increased tumor burden. These results indicate that VEGF signaling insufficiency affects organ aging in mice and suggest that modulating this pathway may result in increased mammalian life span and improved overall health.

Photobiomodulation Response From 660 nm is Different and More Durable Than That From 980 nm

BACKGROUND AND OBJECTIVES

Photobiomodulation (PBM) therapy uses light at various wavelengths to stimulate wound healing, grow hair, relieve pain, and more-but there is no consensus about optimal wavelengths or dosimetry. PBM therapy works through putative, wavelength-dependent mechanisms including direct stimulation of mitochondrial respiration, and/or activation of transmembrane signaling channels by changes in water activity. A common wavelength used in the visible red spectrum is ~660 nm, whereas recently ~980 nm is being explored and both have been proposed to work via different mechanisms. We aimed to gain more insight into identifying treatment parameters and the putative mechanisms involved.

STUDY DESIGN/MATERIALS AND METHODS

Fluence-response curves were measured in cultured keratinocytes and fibroblasts exposed to 660 or 980 nm from LED sources. Metabolic activity was assessed using the MTT assay for reductases. ATP production, a major event triggered by PBM therapy, was assessed using a luminescence assay. To measure the role of mitochondria, we used an ELISA to measure COX-1 and SDH-A protein levels. The respective contributions of cytochrome c oxidase and ATP synthase to the PBM effects were gauged using specific inhibitors.

RESULTS

Keratinocytes and fibroblasts responded differently to exposures at 660 nm (red) and 980 nm (NIR). Although 980 nm required much lower fluence for cell stimulation, the resulting increase in ATP levels was short-term, whereas 660 nm stimulation elevated ATP levels for at least 24 hours. COX-1 protein levels were increased following 660 nm treatment but were unaffected by 980 nm. In fibroblasts, SDH-A levels were affected by both wavelengths, whereas in keratinocytes only 660 nm light impacted SDH-A levels. Inhibition of ATP synthase nearly completely abolished the effects of both wavelengths on ATP synthesis. Interestingly, inhibiting cytochrome c oxidase did not prevent the rise in ATP levels in response to PBM treatment.

CONCLUSION

To the best of our knowledge, this is the first demonstration of differing kinetics in response to PBM therapy at red versus NIR wavelength. We also found cell-type-specific differences in PBM therapy response to the two wavelengths studied. These findings confirm that different response pathways are involved after 660 and 980 nm exposures and suggest that 660 nm causes a more durable response. © 2021 Wiley Periodicals LLC.

Construction and validation of UV-C decontamination cabinets for filtering facepiece respirators

We present evidence-based design principles for three different UV-C based decontamination systems for N95 filtering facepiece respirators (FFRs) within the context of the SARS-CoV-2 outbreak of 2019-2020. The approaches used here were created with consideration for the needs of low- and middle-income countries (LMICs) and other under-resourced facilities. As such, a particular emphasis is placed on providing cost-effective solutions that can be implemented in short order using generally available components and subsystems. We discuss three optical designs for decontamination chambers, describe experiments verifying design parameters, validate the efficacy of the decontamination for two commonly used N95 FFRs (3M, #1860 and Gerson #1730), and run mechanical and filtration tests that support FFR reuse for at least five decontamination cycles.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

Skin Microcolumns as a Source of Paracrine Signaling Factors

Objective: We recently developed the approach of using “microcolumns” of autologous full-thickness skin tissue for wound repair. The small size of these micro skin tissue columns (MSTCs, ∼0.5 mm in diameter) allows donor sites to heal quickly without scarring. Treatment with MSTCs significantly accelerate wound healing, and suppled various skin cell types and skin structures to replenish the wound volume. This technology is now starting clinical use. In this study, we investigate whether MSTCs may also influence wound healing by releasing soluble signaling factors.

Approach: Freshly harvested MSTCs were incubated in culture medium for 24 h. The conditioned medium was collected and tested for its effects on migration and proliferation of human dermal fibroblasts, and its ability to induce tube formation by human umbilical vein endothelial cells (HUVECs). Proteins released into the conditioned medium were characterized by multiplex enzyme-linked immunosorbent assay (ELISA), and compared with medium conditioned by an equivalent mass of intact full-thickness skin.

Results: MSTC-conditioned medium increased fibroblast migration and proliferation, as well as HUVEC tube formation. MSTCs released many soluble factors known to play prominent roles in wound healing. A subset of proteins showed significantly different release profiles compared with intact full-thickness skin.

Innovation: The technology for harvesting and using MSTCs to augment wound healing was recently developed as an alternative to conventional autologous skin grafting. This study shows that MSTCs could also function as “cytokine factories.”

Conclusion: In addition to supplying autologous cells to repopulate the wound volume, MSTCs can also function as a source of growth factors and cytokines to further enhance wound healing.

When Wounds Are Good for You: The Regenerative Capacity of Fractional Resurfacing and Potential Utility in Chronic Wound Prevention

Significance: Fractional resurfacing involves producing arrays of microinjuries on the skin, by thermal or mechanical means, to trigger tissue regeneration. Originally developed for cosmetic enhancement, fractional resurfacing induces a broad array of improvements in the structural and functional qualities of the treated skin and is especially effective at returning defective skin to a more normal state. In addition to fascinating questions about the nature of this remarkable regenerative capacity, there may be potential utility in ulcer prevention by halting or even reversing the progressive decline in overall skin quality that usually precedes chronic wound development. Recent Advances: Photoaging and scarring are the two skin defects most commonly treated by fractional resurfacing, and the treatment produces profound and long-lasting improvements in skin quality, both clinically and at the cellular/histologic level. Chronic wounds usually occur in skin that is compromised by various pathologic factors, and many of the defects found in this ulcer-prone skin are similar to those that have seen improvements after fractional resurfacing. Critical Issues: The mechanisms responsible for the regenerative capacity of fractional resurfacing are mostly unknown, as is how ulcer-prone skin, which is usually afflicted by stressors external to the skin tissue itself, would respond to fractional resurfacing. Future Directions: Better understanding of the cellular and molecular mechanisms underlying the unique healing response to fractional resurfacing could reveal fundamental information about adult tissue regeneration, lead to improvements in current applications, as well as new therapies in other pathologic conditions.

Apparatus for Harvesting Tissue Microcolumns

This manuscript describes the production process for a laboratory apparatus, made from off-the-shelf components, that can be used to collect microcolumns of full-thickness skin tissue. The small size of the microcolumns allows donor sites to heal quickly without causing donor site scarring, while harvesting full-thickness tissue enables the incorporation of all cellular and extracellular components of skin tissue, including those associated with deeper dermal regions and the adnexal skin structures, which have yet to be successfully reproduced using conventional tissue engineering techniques. The microcolumns can be applied directly into skin wounds to augment healing, or they can be used as the autologous cell/tissue source for other tissue engineering approaches. The harvesting needles are made by modifying standard hypodermic needles, and they can be used alone for harvesting small amounts of tissue or coupled with a simple suction-based collection system (also made from commonly available laboratory supplies) for high-volume harvesting to facilitate studies in large animal models.

Laser-assisted delivery of synergistic combination chemotherapy in in vivo skin

The effectiveness of topical drugs for treatment of non-melanoma skin cancer is greatly reduced by insufficient penetration to deep skin layers. Ablative fractional lasers (AFLs) are known to enhance topical drug uptake by generating narrow microchannels through the skin, but information on AFL-drug delivery in in vivo conditions is limited. In this study, we examined pharmacokinetics, biodistribution and toxicity of two synergistic chemotherapy agents, cisplatin and 5-fluorouracil (5-FU), following AFL-assisted delivery alone or in combination in in vivo porcine skin. Detected at 0-120 h using mass spectrometry techniques, we demonstrated that fractional CO₂ laser pretreatment (196 microchannels/cm², 852 μm ablation depth) leads to rapid drug uptake in 1500 μm deep skin layers, with a sixfold enhancement in peak cisplatin concentrations versus non-laser-treated controls (5 h, P = 0.005). Similarly, maximum 5-FU deposition was measured within an hour of AFL-delivery, and exceeded peak deposition in non-laser-exposed skin that had undergone topical drug exposure for 5 days. Overall, this accelerated and deeper cutaneous drug uptake resulted in significantly increased inflammatory and histopathological effects. Based on clinical scores and transepidermal water loss measurement, AFL intensified local toxic responses to drugs delivered alone and in combination, while systemic drug exposure remained undetectable. Quantitative histopathologic analyses correspondingly revealed significantly reduced epidermal proliferation and greater cellular apoptosis after AFL-drug delivery; particularly after combined cisplatin + 5-FU exposure. In sum, by overcoming the primary limitation of topical drug penetration and providing accelerated, enhanced and deeper delivery, AFL-assisted combination chemotherapy may represent a promising treatment strategy for non-melanoma skin cancer.

Attenuating the rate of total body fat accumulation and alleviating liver damage by oral administration of vitamin D-enriched edible mushrooms in a diet-induced obesity murine model is mediated by an anti-inflammatory paradigm shift

Background

Hypovitaminosis D is associated with many features of the metabolic syndrome, including non-alcoholic fatty liver disease. Vitamin D-enriched mushrooms extracts exert a synergistic anti-inflammatory effect. The aim of the present study is to determine the immunomodulatory effect of oral administration of vitamin D-enriched mushrooms extracts on high-fat diet (HFD) animal model of non-alcoholic steatohepatitis (NASH).

Methods

C57BL/6 mice on HFD were orally administered with vitamin D supplement, Lentinula edodes (LE) mushrooms extract, or vitamin D-enriched mushrooms extract for 25 weeks. Mice were studied for the effect of the treatment on the immune system, liver functions and histology, insulin resistance and lipid profile.

Results

Treatment with vitamin D-enriched LE extracts was associated with significant attenuation of the rate of total body fat accumulation, along with a decrease in hepatic fat content as measured by an EchoMRI. Significant alleviation of liver damage manifested by a marked decrease in ALT, and AST serum levels (from 900 and 1021 U/L in the control group to 313 and 340; 294 and 292; and 366 and 321 U/L for ALT and AST, in Vit D, LE and LE + Vit D treated groups, respectively). A corresponding effect on hepatocyte ballooning were also noted. A significant decrease in serum triglycerides (from 103 to 75, 69 and 72 mg/dL), total cholesterol (from 267 to 160, 157 and 184 mg/dL), and LDL cholesterol (from 193 mg/dL to 133, 115 and 124 mg/dL) along with an increase in the HDL/LDL ratio, and improved glucose levels were documented. These beneficial effects were associated with a systemic immunomodulatory effect associated with an increased CD4/CD8 lymphocyte ratio (from 1.38 in the control group to 1.69, 1.71 and 1.63), and a pro- to an anti-inflammatory cytokine shift.

Conclusions

Oral administration of vitamin-D enriched mushrooms extracts exerts an immune modulatory hepato-protective effect in NASH model.

Reconstitution of full-thickness skin by microcolumn grafting

In addition to providing a physical barrier, skin also serves a diverse range of physiological functions through different specialized resident cell types/structures, including melanocytes (pigmentation and protection against ultraviolet radiation), Langerhans cells (adaptive immunity), fibroblasts (maintaining extracellular matrix, paracrine regulation of keratinocytes), sweat glands (thermoregulation) and hair follicles (hair growth, sensation and a stem cell reservoir). Restoration of these functional elements has been a long-standing challenge in efforts to engineer skin tissue, while autologous skin grafting is limited by the scarcity of donor site skin and morbidity caused by skin harvesting. We demonstrate an alternative approach of harvesting and then implanting μm-scale, full-thickness columns of human skin tissue, which can be removed from a donor site with minimal morbidity and no scarring. Fresh human skin microcolumns were used to reconstitute skin in wounds on immunodeficient mice. The restored skin recapitulated many key features of normal human skin tissue, including epidermal architecture, diverse skin cell populations, adnexal structures and sweat production in response to cholinergic stimulation. These promising preclinical results suggest that harvesting and grafting of microcolumns may be useful for reconstituting fully functional skin in human wounds, without donor site morbidity. © 2016 The Authors Journal of Tissue Engineering and Regenerative Medicine Published by John Wiley & Sons Ltd.

Micro-fractional, directional skin tightening: A porcine model

BACKGROUND AND OBJECTIVE

Skin changes are among the most visible signs of aging. Fractional ablative lasers improve skin quality by making small skin wounds that heal rapidly without scarring. While they improve skin texture and discoloration, there is minimal effect on skin laxity. This study was performed to assess skin shrinkage performed by removing multiple small full-thickness skin columns with coring needles combined with wound closure.

MATERIALS AND METHODS

In 5 swine 116 squares (3 cm(2) ) were demarcated for treatment and control sites. In treatment sites 10% of the skin was removed by full-thickness skin coring needles (19 gauge) and afterwards closed and compressed with an elastic adhesive dressing. This procedure was compared to puncturing the skin with standard hypodermic needles (without tissue removal) and subsequent closure with compressive dressing. Area and shape of sites were measured before and 28 days after treatment.

RESULTS

Test and control sites healed within a week without scarring. Coring with wound closure caused significant shrinkage after 28 days. The treated skin area was reduced by 9% (P < 0.0001) and the direction of shrinkage was influenced by the direction of wound closure. Coring without wound closure and puncturing the skin without tissue removal produced an insignificant 3% decrease in area.

CONCLUSION

Significant minimally invasive skin tightening in a preferred direction can be achieved by removing skin with coring needles followed by wound closure. The direction of shrinkage is influenced by the direction of micro-hole closure, irrespective of the skin tension lines. This approach may allow reshaping the skin in a desired direction without scarring.