Pressure Combined with Ischemia/Reperfusion Injury Induces Deep Tissue Injury via Endoplasmic Reticulum Stress in a Rat Pressure Ulcer Model

A Comparative Study on Platelet-Rich Plasma From Elderly Individuals and Young Adults to Treat Pressure Ulcers in Mice

OBJECTIVE

The aim of the present study was to compare the therapeutic effects of activated platelet-rich plasma (PRP) prepared from elderly individuals and young adults to treat pressure ulcers (PUs), and to accumulate a theoretical basis for allogeneic PRP treatment of PUs in elderly patients.

MATERIALS AND METHODS

Whole blood was extracted from elderly individuals aged >65 y and young adult volunteers for PRP preparation, and platelet concentrations in whole blood and PRP were compared. Growth factors released from activated PRP were assayed using the enzyme-linked immunosorbent assay. C57BL/6 mice were divided into three groups: the control saline, elderly-PRP (Group A), and young adult-PRP (Group B). Ischemia-reperfusion injury-induced PUs were established on the backs of mice. PUs were photographed on days 0, 5, and 10 to assess their sizes. Specimens were collected on day 10 and subjected to hematoxylin and eosin and Masson's staining. Immunohistochemical staining for CD31 was conducted to evaluate vascular formation, and cell invasion was assessed using a Transwell assay. The action of PRP on transforming growth factor-beta (TGF-β)-dependent fibroblast activity and epithelial-mesenchymal transition was analyzed using immunofluorescence and Western blotting in vitro.

RESULTS

The platelet concentrations in whole blood and PRP of young adults were significantly higher than that in elderly individuals. The two PRP treatment groups had similar platelet enrichment coefficients of PRP. After activation, PRP from young adults produced significantly higher levels of platelet-derived growth factor, TGF-β, and vascular endothelial growth factor than PRP from elderly individuals (P < 0.05). The concentrations of platelet-derived growth factor, TGF-β, and vascular endothelial growth factor were positively correlated with the platelet concentrations in whole blood and PRP. The effects of PRP in regulating the expressions of TGF-β, α-smooth muscle actin, vimentin, and E-cadherin were observed in vivo and in vitro. The two PRP treatment groups exhibited better wound healing than the control group, as evidenced by more re-epithelialization, higher collagen content, skin fibrosis, and more blood vessel formation over time. Group B exhibited better wound healing than Group A (P < 0.05).

CONCLUSION

PRP exhibits potent wound healing ability in PU therapy, and PRP from young adults is seemingly superior to that from elderly individuals because of a higher concentration of platelets and increased production of growth factors.

A Guide to Perforator Flap Selection for Buttock Pressure Sore Reconstruction

ABSTRACT

Perforator flaps have been increasingly used to repair stage IV buttock pressure ulcers. However, no one has proposed an approach for stage IV buttock pressure ulcers repairing based on the subregion of buttock pressure ulcers. This study aims to evaluate the effect of perforator flaps in the repair of stage IV buttock pressure ulcers, and flap selection was based on the location of the pressure ulcers. Over the past 5 years, we evaluated 65 cases of stage IV buttock pressure ulcers repaired using perforator flaps. Flap selection was based on the subregion of each buttock pressure ulcer, following our approach. A total of 87 perforator flaps were used for 65 cases, including 42 superior gluteal artery perforator flaps, 19 fourth lumbar artery perforator flaps, and 26 descending inferior gluteal artery perforator flaps. All patients showed satisfactory reconstruction. The authors' approach can support surgeons in selecting the appropriate flaps to repair stage IV buttock pressure ulcers and achieve excellent reconstructive outcomes. This method makes the selection of flaps for pressure ulcer repair systematic, simple, and highly feasible and thus is worthy of promotion.

Multivariate analysis and nursing intervention strategies for intraoperative pressure ulcers in patients undergoing craniocerebral microsurgery

OBJECTIVE

This study aimed to investigate the various influencing factors for intraoperative pressure sores in patients with craniocerebral microsurgery and provide nursing intervention strategies for surgical pressure sores in a clinical operating room.

METHODS

This was a case-control study on 2157 patients who underwent craniocerebral microsurgery in the craniocerebral department of the hospital between November 2021 and November 2022. Of these, 62 patients with intraoperative pressure sores were compared with 248 patients without pressure sores during the same period using a 1:4 case-control method. A logistic regression model was used to analyze the effect of possible factors on pressure sores in an operating room.

RESULTS

The incidence of pressure sores in craniocerebral microsurgery was 2.87%. The logistic regression analysis showed that skin at the pressure site [odds ratio (OR) = 1.759, 95% confidence interval (CI): 1.137-2.721], surgical position (OR = 1.727, 95% CI: 1.338-2.228), intraoperative body temperature (OR = 2.229, 95% CI: 1.229-4.042), and surgical time (OR = 2.009, 95% CI: 1.221-3.303) were independent factors for the occurrence of intraoperative pressure sores.

CONCLUSIONS

The high-risk factors for pressure sores in craniocerebral microsurgery included fasting time, surgical position, intraoperative temperature, and skin at the pressure site. Targeted attention and protection had a positive effect in preventing intraoperative pressure sores in patients who underwent craniocerebral microsurgery.

Targeting Cx43 to Reduce the Severity of Pressure Ulcer Progression

In the skin, repeated incidents of ischemia followed by reperfusion can result in the breakdown of the skin and the formation of a pressure ulcer. Here we gently applied paired magnets to the backs of mice to cause ischemia for 1.5 h and then removed them to allow reperfusion. The sterile inflammatory response generated within 4 h causes a stage 1 pressure ulcer with an elevation of the gap junction protein Cx43 in the epidermis. If this process is repeated the insult will result in a more severe stage 2 pressure ulcer with a breakdown of the epidermis 2-3 days later. After a single pinch, the elevation of Cx43 in the epidermis is associated with the inflammatory response with an increased number of neutrophils, HMGB1 (marker of necrosis) and RIP3 (responsible for necroptosis). Delivering Cx43 specific antisense oligonucleotides sub-dermally after a single insult, was able to significantly reduce the elevation of epidermal Cx43 protein expression and reduce the number of neutrophils and prevent the elevation of HMGB1 and RIP3. In a double pinch model, the Cx43 antisense treatment was able to reduce the level of inflammation, necroptosis, and the extent of tissue damage and progression to an open wound. This approach may be useful in reducing the progression of stage 1 pressure ulcers to stage 2.

Calreticulin: a multifunctional protein with potential therapeutic applications for chronic wounds

Calreticulin is recognized as a multifunctional protein that serves an essential role in diverse biological processes that include wound healing, modification and folding of proteins, regulation of the secretory pathway, cell motility, cellular metabolism, protein synthesis, regulation of gene expression, cell cycle regulation and apoptosis. Although the role of calreticulin as an endoplasmic reticulum-chaperone protein has been well described, several studies have demonstrated calreticulin to be a highly versatile protein with an essential role during wound healing. These features make it an ideal molecule for treating a complex, multifactorial diseases that require fine tuning, such as chronic wounds. Indeed, topical application of recombinant calreticulin to wounds in multiple models of wound healing has demonstrated remarkable pro-healing effects. Among them include enhanced keratinocyte and fibroblast migration and proliferation, induction of extracellular matrix proteins, recruitment of macrophages along with increased granulation tissue formation, all of which are important functions in promoting wound healing that are deregulated in chronic wounds. Given the high degree of diverse functions and pro-healing effects, application of exogenous calreticulin warrants further investigation as a potential novel therapeutic option for chronic wound patients. Here, we review and highlight the significant effects of topical application of calreticulin on enhancing wound healing and its potential as a novel therapeutic option to shift chronic wounds into healing, acute-like wounds.

Advance in topical biomaterials and mechanisms for the intervention of pressure injury

Pressure injuries (PIs) are localized tissue damage resulting from prolonged compression or shear forces on the skin or underlying tissue, or both. Different stages of PIs share common features include intense oxidative stress, abnormal inflammatory response, cell death, and subdued tissue remodeling. Despite various clinical interventions, stage 1 or stage 2 PIs are hard to monitor for the changes of skin or identify from other disease, whereas stage 3 or stage 4 PIs are challenging to heal, painful, expensive to manage, and have a negative impact on quality of life. Here, we review the underlying pathogenesis and the current advances of biochemicals in PIs. We first discuss the crucial events involved in the pathogenesis of PIs and key biochemical pathways lead to wound delay. Then, we examine the recent progress of biomaterials-assisted wound prevention and healing and their prospects.

Adipose Tissue in Peripheral Obesity as an Assessment Factor for Pressure Ulcers

Scope and Significance: Pressure ulcers are very difficult to treat and pose an economic burden, just below cancer and cardiovascular illness, at 4.82 billion U.S. dollars. It is important to understand the pathophysiology of the condition, risk stratification, and ways of preventing it. Prevention forms the most important aspect of their management. The authors systematically evaluated the existing risk prediction scales and explored the evidence from literature regarding the role of additional factors including body mass index, obesity, subcutaneous tissue thickness, and skin integrity in pressure ulcers. With this review it is hoped that the future management of pressure ulcers will concentrate on the preventable and alterable factors in its pathophysiology. Translational Relevance: The review focuses on how adipose tissue thickness can predict the occurrence of pressure ulcer. If adequately proved that a definite thickness of peripheral adipose tissue is efficient in prevention of pressure ulcers, then methods of maintaining the thickness of this tissue will be the next effective strategy in the management of this chronic issue. Clinical Relevance: The review addresses the management of pressure ulcers to wound care providers and emphasize on confounding parameters of obesity, subcutaneous tissue thickness, and skin integrity during the treatment regimen of pressure ulcers. Objectives: The main objective of this review is to draw a consensus concerning the role of adipose tissue in pressure ulcers, based on the published research. A review of the various preexisting predictive scales for pressure ulcers is a secondary objective to highlight the shortcomings in ulcer management. This review finally aims in the future at paving a way to refine our prognosticating scales for pressure sores based on these results. Accurate preventative injury risk scales are needed so that preventative resources can be directed to the patients for whom they are the most appropriate.

Diabetic foot ulcers: Classification, risk factors and management

Diabetic foot ulceration is a devastating complication of diabetes that is associated with infection, amputation, and death, and is affecting increasing numbers of patients with diabetes mellitus. The pathogenesis of foot ulcers is complex, and different factors play major roles in different stages. The refractory nature of foot ulcer is reflected in that even after healing there is still a high recurrence rate and amputation rate, which means that management and nursing plans need to be considered carefully. The importance of establishment of measures for prevention and management of DFU has been emphasized. Therefore, a validated and appropriate DFU classification matching the progression is necessary for clinical diagnosis and management. In the first part of this review, we list several commonly used classification systems and describe their application conditions, scope, strengths, and limitations; in the second part, we briefly introduce the common risk factors for DFU, such as neuropathy, peripheral artery disease, foot deformities, diabetes complications, and obesity. Focusing on the relationship between the risk factors and DFU progression may facilitate prevention and timely management; in the last part, we emphasize the importance of preventive education, characterize several of the most frequently used management approaches, including glycemic control, exercise, offloading, and infection control, and call for taking into account and weighing the quality of life during the formulation of treatment plans. Multidisciplinary intervention and management of diabetic foot ulcers (DFUs) based on the effective and systematic combination of these three components will contribute to the prevention and treatment of DFUs, and improve their prognosis.

Sodium Danshensu Cream Promotes the Healing of Pressure Ulcers in Mice through the Nrf2/HO-1 and NF-κB Pathways

On the basis of the mice pressure ulcers (PU) model, the protective effect and potential mechanism of sodium Danshensu (SDSS) cream against PU were investigated. The mice were randomly divided into three groups: the negative control group (cream without 0.5 g SDSS), the SDSS group (cream containing 0.5 g SDSS), and the positive group (0.5 g Hirudoid®). After 7 and 14 days of ointment application, the wound-healing rate of the SDSS and positive groups was significantly higher than that of the control group (p < 0.05). The results of hematoxylin−eosin staining also indicated that SDSS has the potential to promote the healing of PU. In addition, the serum IL-6, IL-1β, TNF-α, and MDA levels decreased significantly (p < 0.01) after 14 days of SDSS treatment, while the SOD, CAT, and GSH-Px activities increased significantly (p < 0.01). In addition, SDSS cream was able to significantly increase the expression of Nrf2, HO-1, GCLM, NQO1, NF-κB p65, NF-κB p50, IKKα, and IKKβ while decreasing the expression of Keap1 and IκBαin the Nrf2/HO-1 and NF-κB pathways. Our research will provide a foundation for the future clinical prevention and treatment of PU with SDSS cream.

APACHE scoring system and pressure injury risk for intensive care patients: A systematic review and meta-analysis

The present study was designed to determine the association between Acute Physiology and Chronic Health Evaluation (APACHE) scale and elevated pressure injure (PI) risk in intensive care units (ICU) and also evaluate the predictive value of APACHE score in PI patients. Comprehensive strategies were used to search studies from PubMed, Web of Science, and Ovid Embase electronic databases for observational studies that provided data about APACHE scores related to PI in ICU. Eligible studies were selected based on inclusion and exclusion criteria. The pooled SMD with 95% confidence intervals were calculated. A summary ROC curve was plotted to calculate area under curve (AUC) for APACHE-II (15-20). Twenty-one studies involving 11,102 patients who met selection criteria were included. The 11.0% of patients (1229/11102) in ICU developed PIs. Overall, the PI group had a higher score compared with the non-PI group in the APACHE II (22.1 ± 8.0 vs. 14.5 ± 7.4, mean ± SD). The APACHE-III of PI patients was significantly more than that in the non-PI group (79.9 ± 25.6 vs. 59.9 ± 30.4, mean ± SD). The pooled SMD was 0.82 (95% CI: 0.58-1.06, I²  = 91.7%, p-value < 0.001). The subgroup analysis revealed that the risk of PIs did not vary with the type of APACHE score (II, III, IV) and the type of study design (case-control, cross-sectional, cohort, longitudinal study). Proportion of males (I²  = 91.68%, p value = 0.090), publish year (I²  = 91.96%, p value = 0.187) and mean age of patients (I²  = 91.96%, p value = 0.937) were not the sources of heterogeneity. APACHE-II (15-20) achieves the best predictive performance in PI, and the prediction accuracy was balanced with equal sensitivity and specificity (Sen: 0.72, 0.62-0.80; Spec: 1.72, 1.25-2.38). In conclusion, higher APACHE scores are frequently accompanied by a higher incidence of PI among critical-care patients. APACHE-II scores (15-20) satisfactorily predicted PI, and strategies to prevent PI should be aggressively implemented.

Effect of Vibration on Alleviating Foot Pressure-Induced Ischemia under Occlusive Compression

Objectives

Foot ulcers often occur in people with diabetes because of pressure-induced tissue ischemia. Vibration has been reported to be helpful in alleviating mechanical damage and promoting wound healing. The objective of this study is to explore whether vibration can relieve reactive hyperemia in foot tissue under occlusive compression.

Methods

Thirteen healthy adults participated in the study. Each foot was placed under occlusive compression without or with vibration intervention, which was randomly assigned every other day. The dorsal foot skin blood flow (SBF) was measured pre- and postintervention for each subject in each test. Temporal variations and spectral features of SBF were recorded for comparison.

Results

The results showed that subjects displayed an obvious reactive hyperemia in the foot tissue after pressure occlusion, whereas they displayed a more regular SBF when vibration was applied along with occlusive compression. Moreover, the amplitude of metabolic, neurogenic, and myogenic pathways for SBF was significantly reduced during the hyperemia process when vibration was applied.

Conclusions

This study demonstrated that vibration can effectively reduce the level of hyperemia in foot tissue under occlusive compression and also induce less protective physiological regulatory activities. This is helpful for protecting foot tissue from pressure-induced ischemic injury and foot ulcers.

Low temperature exerts protective effects by inhibiting mitochondria-mediated apoptosis pathway following pressure injury to rat muscle

OBJECTIVE

We aimed to determine the effect of different low-temperature range interventions at different time-points in a rat model of pressure injury (PI) produced by Ischemia/Reperfusion (I/R) injury.

METHODS

Sprague-Dawley rats were randomly assigned to blank control, injury control, and temperature intervention groups. Rats in the injury control and temperature intervention groups (involving exposure to different temperature range at different time-points) were subjected to three cycles of I/R injury with 2-h ischemia and 0.5-h reperfusion to induce PI.

RESULTS

The muscle tissues exhibited degenerative changes after compression. Low temperature intervention of 16-18°C in the ischemia period resulted in the lowest degree of tissue damage and significantly decreased levels of Bcl-2-associated X protein (Bax), caspase-9, and caspase-3. Moreover, it resulted in the highest expression level of B-cell lymphoma 2 (Bcl-2) and lowest expression levels of Bax, caspase-9, and caspase-3 in muscle tissues among all intervention groups.

CONCLUSION

Low-temperature intervention at 16-18°C during the ischemia period showed optimal effects on the expressions of apoptotic factors during the development of PI with I/R-induced tissue damage.

Risk Factors for Pressure Injury Development Among Critical Care Patients

Identification of the appropriate pressure injury (PI) risk factors is the first step in successful PI prevention. Measuring PI risk through formalized PI risk assessment is an essential component of any PI prevention program. Major PI risk factors identified in the empirical literature in the critical care population include age, diabetes, hypotension, mobility, prolonged intensive care unit admission, mechanical ventilation and vasopressor administration. Future risk assessment using sophisticated data analytics available in the electronic medical record may result in earlier, targeted PI prevention and will improve our understanding of risk factors that may contribute to unavoidable PIs.

Determination of three Unsaturated Fatty Acids in Pressure Ulcer Rats Using A UPLC-MS/MS Method

Background:

The serum levels of Docosahexaenoic Acid (DHA), Eicosapentaenoic Acid (EPA) and Arachidonic Acid (AA) under the state of Pressure Ulcers (PUs) are still unclear.

Introduction:

In order to investigate serum levels of DHA, EPA, and AA in PUs rats, an ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/ MS) method was developed and validated.

Methods:

Chromatographic separation of DHA, EPA, AA was carried out on a BEH C18 column and gradient elute consisted of 5 mM ammonium acetate-0.1% formic acid and acetonitrile. Subsequently, fifty rats were divided into five groups (n=10), four PU groups (A-D) underwent various pressure and release time protocols, with group E as the control. The concentrations of DHA, EPA, AA from five groups were determined by using a validated method.

Results:

The results showed there was good linearity for DHA (327.3/283.4), EPA (301.2/257.0), and AA (303.1/258.9) within 0.05-6.4 μg/mL. In control group, the levels of DHA, AA and EPA were 1.16±0.68, 0.59±0.19 and 0.78±0.21 μg/mL. At the end of modeling, concentrations of DHA, EPA and AA were increased after long and persistent pressure (>8 h). Especially, the level of DHA was significantly higher (P<0.01) than that of control group.

Conclusion:

A stable, rA stable, reliable and accurate UPLC-MS/MS for determination of DHA, EPA, AA in blood was developed. Serum concentrations of DHA, EPA and AA were altered differently after long and persistent pressure (>8 h), and DHA is a remarkable one.eliable and accurate UPLC-MS/MS for determination of DHA, EPA, AA in blood was developed. Serum concentrations of DHA, EPA and AA were altered differently after long and persistent pressure (>8 h), and DHA is a remarkable one.

Quantitative iTRAQ LC-MS/MS reveals muscular proteome profiles of deep pressure ulcers

Pressure ulcers (PUs) are a common clinical issue lacking effective treatment and validated pharmacological therapy in hospital settings. Ischemia-reperfusion injury of deep tissue, especially muscle, plays a vital role in the formation and development of the overwhelming majority of PUs. However, muscular protein expression study in PUs has not been reported. Herein, we aimed to investigate the muscular proteins profiles in PUs and to explore the pathological mechanism of PUs. The iTRAQ LC-MS/MS was conducted to detect the protein profiles in clinical muscle samples of PUs. The GO and KEGG pathways analyses were performed for annotation of differentially expressed proteins. Protein-protein interaction (PPI) network was constructed by STRING online database, and hub proteins were validated by the immunoblotting. Based on proteomics results, we found a number of proteins that were differentially expressed in PU muscle samples compared with the normal and identified unique proteins expression patterns between these two groups, suggesting that they might involve in pathological process of the disease. Importantly, cathepsin B and D, as well as other autophagy-lysosome and apoptosis associated proteins were identified. Further experiments characterize the expression of these proteins and their regulation in the process of apoptosis and autophagy. These findings may provide novel insights into the mechanisms of lysosome-associated pathways involved in the initiation of PUs. This is the first study linking proteomics to PUs muscle tissues, which indicated cathepsin B and D might be key drug target for PUs.

Endoplasmic reticulum stress in human chronic wound healing: Rescue by 4-phenylbutyrate

During wound healing, cells have a high rate of protein synthesis and many proteins need to be folded post‐translationally to function, which occurs in the endoplasmic reticulum (ER). In addition to proliferation, several cellular stress conditions, such as hypoxia, in the wound micro‐environment lead to the accumulation of unfolded or misfolded proteins in the ER, causing ER stress. Eukaryotic cells have a signalling system to manage ER stress called the unfolded protein response (UPR). Mild UPR activation has a beneficial homeostatic effect; however, excessive UPR induces cell death. Herein, we examined venous leg ulcer biopsies versus normal acute incisional wounds in age‐matched elderly subjects and found a large increase in ER stress markers. To study the underlying mechanism, we established several cell cultures from amputated legs from the elderly that showed inherent ER stress. While both keratinocytes and fibroblasts migration was impaired by ER stress, migration of elderly leg skin keratinocytes was markedly improved after treatment with the chemical chaperone and clinically established drug 4‐phenylbutyrate (4‐PBA) and demonstrated a reduction in ER stress markers. In a full‐thickness human skin wound healing model, 4‐PBA improved the reepithelialisation rate, which suggests it as a promising drug repurposing candidate for wound healing.

Skin and Mucosal Damage in Patients Diagnosed With COVID-19: A Case Report

Patients admitted to the intensive care unit (ICU) are at a high risk for developing pressure injuries. A patient requiring multiorgan support is at a higher risk for pressure injuries related to immobility, sedation, vasopressors, and hypoxia. To mitigate pressure injuries, our hospital utilizes a bundle approach to prevent skin injury. However, despite efforts to prevent pressure injuries, we found our patients in the ICU with the diagnosis of COVID-19 went on to develop significant pressure and mucosal injuries. This is a case report of 4 patients diagnosed with COVID-19 who developed significant skin and mucosal injuries during their ICU admissions in the month of March 2020. We found that patients developed skin conditions that were initially thought to be deep-tissue injuries (DTIs) early in the admission. The DTIs progressed over the course of the admission in the ICU and evolved to thick adherent eschar that appeared to be unstageable pressure injuries, which extended beyond the soft tissue directly over the bony prominence. We also found that skin damage to the mucosa of the nares, tongue, lips, and urethra presented first as inflammation and then progressed to thick eschar. Despite maximum pressure relief with the use of a pressure-relieving turn and position system, bordered foam dressings, fluidized positioners, specialty beds, and leadership support for twice-a-week skin checks, our patients diagnosed with COVID-19 developed extensive skin damage across the fleshy portion of the buttocks and on the mucosa of the nares, tongue, lips, and urethra during minimal exposure to pressure. Although the initial presentation of the skin damage appeared to be related to pressure, the extent of the skin damage suggests a vascular inflammatory process beyond skin damage related to pressure.

Tazarotene-loaded PLGA nanoparticles potentiate deep tissue pressure injury healing via VEGF-Notch signaling

BACKGROUND AND PURPOSE

New capillaries are essential for deep tissue pressure injury wound healing. Tazarotene is a recently discovered small molecule drug and functions to promote neovascularization and tissue repair. At present, the application of tazarotene in the repair of pressure injuries has not previously been investigated. This study used poly (lactic-co-glycolic acid) (PLGA) as nanoparticle carriers loaded with tazarotene (Ta/PLGA NPs) for drug delivery and to overcome shortcomings associated with the low water solubility, short half-life, easy photolysis and low bioavailability of tazarotene itself.

METHODS

The physicochemical properties, drug release and bioactivity of Ta/PLGA NPs were examined in vitro by transmission electron microscope, spectrophotometry and cell assays. Mouse models of deep tissue pressure injuries (DTPI) were established and the therapeutic effects and mechanisms of Ta/PLGA NPs in local wound repair were studied.

RESULTS

The results showed that Ta/PLGA NPs were of uniform size and distribution and were non-toxic both in vitro and in vivo. In vivo experiments suggested that Ta/PLGA NPs significantly promoted DTPI wound repair through activation of the VEGF/VEGFR-Notch1/DLL4 signaling pathway.

CONCLUSION

This study highlights the potential clinical significance of implementation of tazarotene small molecule drugs in combination with effective biomaterial carriers for the treatment of chronic refractory wounds, such as DTPI.

Identifying Risk Factors for Pressure Injury in Adult Critical Care Patients

BACKGROUND

Critically ill patients have a variety of unique risk factors for pressure injury. Identification of these risk factors is essential to prevent pressure injury in this population.

OBJECTIVE

To identify factors predicting the development of pressure injury in critical care patients using a large data set from the PhysioNet MIMIC-III (Medical Information Mart for Intensive Care) clinical database.

METHODS

Data for 1460 patients were extracted from the database. Variables that were significant in bivariate analyses were used in a final logistic regression model. A final set of significant variables from the logistic regression was used to develop a decision tree model.

RESULTS

In regression analysis, cardiovascular disease, peripheral vascular disease, pneumonia or influenza, cardiovascular surgery, hemodialysis, norepinephrine administration, hypotension, septic shock, moderate to severe malnutrition, sex, age, and Braden Scale score on admission to the intensive care unit were all predictive of pressure injury. Decision tree analysis revealed that patients who received norepinephrine, were older than 65 years, had a length of stay of 10 days or less, and had a Braden Scale score of 15 or less had a 63.6% risk of pressure injury.

CONCLUSION

Determining pressure injury risk in critically ill patients is complex and challenging. One common pathophysiological factor is impaired tissue oxygenation and perfusion, which may be nonmodifiable. Improved risk quantification is needed and may be realized in the near future by leveraging the clinical information available in the electronic medical record through the power of predictive analytics.

Chitosan hydrogel encapsulated with LL-37 peptide promotes deep tissue injury healing in a mouse model

BACKGROUND

LL-37 peptide is a member of the human cathelicidin family, and has been shown to promote the healing of pressure ulcers. However, the low stability of this peptide within the wound environment limits its clinical use. Chitosan (CS) hydrogel is commonly used as a base material for wound dressing material.

METHODS

CS hydrogel (2.5% w/v) was encapsulated with LL-37. Cytotoxicity of the product was examined in cultured NIH3T3 fibroblasts. Effects on immune response was examined by measuring tumor necrosis factor-α (TNF-α) release from RAW 264.7 macrophages upon exposure to lipopolysaccharides. Antibacterial activity was assessed using Staphylococcus aureus. Potential effect on pressure ulcers was examined using a mouse model. Briefly, adult male C57BL/6 mice were subjected to skin pressure using magnets under a 12/12 h schedule for 21 days. Mice were randomized to receive naked LL-37 (20 μg), chitosan gel containing 20-μg LL-37 (LL-37/CS hydrogel) or hydrogel alone under the ulcer bed (n = 6). A group of mice receiving no intervention was also included as a control.

RESULTS

LL-37/CS hydrogel did not affect NIH3T3 cell viability. At a concentration of 1-5 μg/ml, LL-37/CS inhibited TNF-α release from macrophage. At 5 μg/ml, LL-37/CS inhibited the growth of Staphylococcus aureus. The area of the pressure ulcers was significantly lower in mice receiving LL-37/CS hydrogel in comparison to all other 3 groups on days 11 (84.24% ± 0.25%), 13 (56.22% ± 3.91%) and 15 (48.12% ± 0.28%). Histological examination on days 15 and 21 showed increased epithelial thickness and density of newly-formed capillary with naked LL-37 and more so with LL-37/CS. The expression of key macromolecules in the process of angiogenesis (i.e., hypoxia inducible factor-1α (HIF-1α) and vascular endothelial growth factor-A (VEGF-A)) in wound tissue was increased at both the mRNA and protein levels.

CONCLUSION

Chitosan hydrogel encapsulated with LL-37 is biocompatible and could promote the healing of pressure ulcers.

The comparison of the effects of local cooling and heating on apoptosis and pyroptosis of early-stage pressure ulcers in rats

The exploration of an effective method for preventing and treating pressure ulcers (PUs) is a hot topic in medical research. Recently, disputes about the choice of heat and cold therapies have emerged for the prevention and treatment of clinical PUs. The present study was designed to compare the effect of cool and heat therapies on pyroptosis and apoptosis of early-stage PUs in rats. Sixty SD rats of SPF grade were randomly divided into the sham group, model group, heating group, and cooling group. We established a rat model of early-stage PUs by using an ischemia-reperfusion method. At the end of the experiment, the tissue underneath the compressed region was collected for hematoxylin and eosin staining, transmission electron microscopy, immunohistochemistry, immunofluorescence staining, a TdT-mediated dUTP nick-end labeling assay, a Western blot analysis, and a mitochondrial swelling experiment. Our results suggested that the mitochondrial apoptotic pathway and pyroptosis were involved in the formation of early-stage PUs, and local heating increased the PU injury in rats, while local cooling reduced the PU injury in rats. This study showed that heat therapy might not be suitable for the clinical treatment and care of early-stage PUs, while cold therapy may be more appropriate.

Suppression of microRNA‑27a protects against liver ischemia/reperfusion injury by targeting PPARγ and inhibiting endoplasmic reticulum stress

Liver ischemia‑reperfusion (I/R) injury is an important clinical issue related to liver transplantation. Recent studies suggest that microRNAs are implicated in various biological and pathological processes, including liver I/R injury. This study aimed to investigate the role and potential mechanism of miR‑27a during liver I/R injury. A liver I/R model was induced via 60 min of ischemia and reperfusion for 6 h in rats. Cells were transfected with miR‑27a mimics or the miR‑27a inhibitor to examine the effect of miR‑27a on liver I/R. Apoptotic cells were detected by flow cytometry and TUNEL staining. The expression of miR‑27a was measured by real‑time PCR. The expression of peroxisome proliferator‑activated receptor γ (PPARγ); gastrin‑releasing peptide 78 (GRP78) and C/EBP homologous protein (CHOP) were detected by western blot analysis. The results showed that miR‑27a was significantly upregulated during I/R injury in vivo and in vitro. In addition, miR‑27a inhibitors attenuated hypoxia/reoxygenation (H/R)‑induced oxidative stress, endoplasmic reticulum stress (ERS) and apoptosis in AML12 cells. By contrast, miR‑27a mimics promoted hypoxia/reoxygenation‑induced ERS, and apoptosis. Furthermore, PPARγ was identified as a target gene of miR‑27a using bioinformatic analysis and a dual‑luciferase reporter assay. Knockdown of PPARγ significantly abrogated the inhibitory effect of miR‑27a inhibitors on the ERS pathway. Moreover, the miR‑27a antagomir attenuated liver I/R injury in rats, a finding manifested by reduced ALT/AST, hepatocyte apoptosis, oxidative stress and inhibition of the ERS pathway. Taken together, these findings demonstrate that suppression of miR‑27a protects against liver I/R injury by targeting PPARγ and by inhibiting the ERS pathway.

A Critical Review and Perspective of Honey in Tissue Engineering and Clinical Wound Healing

Significance: Historically, honey has been regarded as a potent agent in bacterial inhibition and wound healing. An increased prevalence of antibiotic resistant pathogens spurred an initial resurgence in honey's clinical popularity, with it quickly finding a place in wound care and regenerative medicine. However, this renewed usage demanded a need for improved delivery and overall research of its bioactive properties. This review provides an overview of the antibacterial properties and clinical use of honey. Recent Advances: The past and present clinical use of honey is noted, focusing specifically on burns and ulcers, as these are the most common applications of the natural agent. While honey is often used without modification clinically, there are also commercially available products ranging from dressings to gels, which are discussed. Critical Issues: Despite these products growing in popularity, the need for improved delivery and a structure to support wound healing could improve the treatment method. Future Directions: Tissue engineering scaffolds can provide an alternative method of honey delivery with research focusing primarily on electrospun scaffolds, hydrogels, and cryogels. Current studies on these scaffolds are discussed with respect to their advantages and potential for future clinical work. Overall, this review provides a comprehensive overview of the properties of honey, its current use in wound healing, and the potential for future incorporation into tissue-engineered scaffolds to provide an innovative wound healing agent.

In vivo label-free functional photoacoustic monitoring of ischemic reperfusion

Pressure ulcer formation is a common problem among patients confined to bed or restricted to wheelchairs. The ulcer forms when the affected skin and underlying tissues go through repeated cycles of ischemia and reperfusion, leading to inflammation. This theory is evident by intravital imaging studies performed in immune cell-specific, fluorescent reporter mouse skin with induced ischemia-reperfusion (I-R) injuries. However, traditional confocal or multiphoton microscopy cannot accurately monitor the progression of vascular reperfusion by contrast agents, which leaks into the interstitium under inflammatory conditions. Here, we develop a dual-wavelength micro electro mechanical system (MEMS) scanning-based optical resolution photoacoustic microscopy (OR-PAM) system for continuous label-free functional imaging of vascular reperfusion in an IR mouse model. This MEMS-OR-PAM system provides fast scanning speed for concurrent dual-wavelength imaging, which enables continuous monitoring of the reperfusion process. During reperfusion, the revascularization of blood vessels and the oxygen saturation (sO₂ ) changes in both arteries and veins are recorded, from which the local oxygen extraction ratios of the ischemic tissue and the unaffected tissue can be quantified. Our MEMS-OR-PAM system provides novel perspectives to understand the I-R injuries. It solves the problem of dynamic label-free functional monitoring of the vascular reperfusion at high spatial resolution.

Prosurvival roles mediated by the PERK signaling pathway effectively prevent excessive endoplasmic reticulum stress-induced skeletal muscle loss during high-stress conditions of hibernation

Stress conditions like hypoxia, ischemia, and ischemia/reperfusion can trigger excessive endoplasmic reticulum stress (ERS), which can lead to cell apoptosis-induced skeletal muscle atrophy in non-hibernators. However, although hibernators experience multiple stress conditions during hibernation, their skeletal muscles appear to be well protected. We hypothesize that hibernators effectively avoid cell apoptosis, at least partially, by controlling ERS level. Here, we focused on the potential occurrence of ERS and how hibernators cope with it during different hibernation states. Results indicated that the protein expression levels of glucose-regulated protein 78 (GRP78), phosphorylated PKR-like ER protein kinase, phosphorylated eukaryotic translation initiation factor 2α (p-eIF2α), and activating transcription factor 4 were significantly increased during hibernation, but primarily recovered in posthibernation. In the torpor-arousal cycle, the expression levels of the above indicators were lower during inter-bout arousal (IBA) than that during late torpor (LT). However, there was no change in C/EBP homologous protein expression and no apoptosis in skeletal muscles during the different hibernation states. In conclusion, the upregulation of p-eIF2α and GRP78 were identified as two crucial mechanisms mediated by the PERK signaling pathway to alleviate elevated ERS. The downregulation of ERS during IBA may be a unique countermeasure for hibernating squirrels to prevent excessive ERS. Thus, these special anti-excessive ERS abilities of ground squirrels contribute to the prevention of skeletal muscle cell apoptosis during hibernation.

Muscular proteomic profiling of deep pressure ulcers reveals myoprotective role of JAK2 in ischemia and reperfusion injury

Pressure ulcers (PUs) are a complex and serious clinical problem. Deep tissue injury (DTI) is either the outcome or the trigger of deep PUs. However, the cellular and molecular mechanisms that contribute to the pathogenesis of deep PUs remain unclear. In this study, the degeneration characteristics and increased autophagy and apoptosis were observed in deep PU muscle tissues. Muscular proteome of deep PU revealed that a total of 520 proteins were differentially expressed, particularly, JAK2 was down-regulated. Intriguingly, expression of JAK2 in C2C12 myoblasts exposed to oxygen-glucose deprivation and reoxygenation (OGD/R) insult was also distinctly reduced. Ex vivo, we transfected C2C12 myoblasts with lentivirus carrying the JAK2 plasmid and found that JAK2-overexpressed myoblasts exhibited a decrease in autophagy and apoptosis after OGD/R treatment, as well as less cell death. Finally, Western blot analysis determined that p-JAK2, p-AKT, p-mTOR and p-ERK1/2 levels were significantly elevated, accompanied by JAK2 overexpression but without p-STAT3, and inhibition of the AKT and ERK1/2 pathway resulted in elevated apoptosis and/or autophagy. These results demonstrated that JAK2 may play an important protective role in muscular ischemia and reperfusion injury during DTI development by inhibition of autophagy and apoptosis through the AKT and ERK1/2 pathways.

Effects of Derinat on ischemia-reperfusion-induced pressure ulcer mouse model

Sodium salt of deoxyribonucleic acid (DNA), Derinat, isolated from the soft roes of Russian sturgeon, has been utilized as an immunomodulator for the treatment of reactive oxygen species (ROS)-associated diseases in clinics. Here we show that treatment with Derinat has an anti-inflammatory and anti-oxidative effects on cutaneous ischemia-reperfusion (IR) injury in pressure ulcer (PU) model mice. Dorsal skin damage and dermal edema in mild PU model mice were attenuated by treatment with Derinat. Immunohistochemical and biochemical analyses showed that Derinat suppressed IR-induced oxidative damage, i.e. accumulation of 8-hydroxy-2'-deoxyguanosine (8-OHdG), and related inflammatory factors such as cyclooxygenase 2 (COX-2) and IL-6 receptor (IL-6R) in dorsal skin from PU model mice. We also verified that phospholyated/non-phosphorylated ratio of extracellular signal-regulated kinase (Erk) and p38 mitogen-activated protein kinase (MAPK) increased after IR, which were attenuated by Derinat. We then compared the effect of Derinat with that of salmon DNA and other PU therapeutic agents, prostaglandin E1 (PGE1) and basic fibroblast growth factor (bFGF), by using severe PU model mice. The effects of Derinat and salmon-DNA were compatible with those of PGE1 and bFGF. These results suggest that Derinat other fish-derived DNA formulation could be effective enough and become intriguing new therapeutic options.

[Effect of different time windows and interventions on skin pressure ulcers and ischemia-reperfusion injury in rats]

OBJECTIVE

To observe the effect of different time windows and interventions on skin pressure ulcers and ischemia-reperfusion (I/R) injury in rats.

METHODS

Sixty?eight SD rats were randomly divided into blank control group (n=4) and model group (n=64). The rats in the model group were randomly divided into group A (n=32) without intervention and group B (n=32) with post?conditioning. The degree of skin compression, neutrophil infiltration and serum levels of free radicals were observed in the rats after compression for 2, 4, 6, and 8 h (8 rats at each time point).

RESULTS

A significant difference was found in the severity of skin damage among the control group, group A, and group B (P=0.001), and the injury was milder in group B than in group A. Severe skin lesions occurred in 2 rats after skin compression for 6 h, as compared with 6 after compression for 8 h (P=0.043), but in none of the rats after compression for 2 or 4. Seventeen rats in group B and 15 in group A showed grade 1 neutrophil infiltration in the skin lesions, and 8 rats in group B and 10 in group A showed grade II neutrophil infiltration (P=0.002). Neutrophil infiltration was the mildest in rats with a 2?h compression, and exacerbated progressively and significantly as the compression time extended (P=0.027). With the prolongation of the intervention time, the rats in both groups A and B showed decreased SOD and increased MDA and NO levels, and overall the I/R injury was milder in 2? and 4?h compression groups than in 6? and 8?h compression groups. The level of serum SOD was significantly higher and MDA and NO levels were significantly higher in group B than in group A (P<0.05).

CONCLUSION

Ischemic post?conditioning can relieve I/R injury in acute pressure ulcer in rats. The effective time window for intervention is within 6 h of ischemia, and the effect of ischemic post-conditioning is optimal within 2 h. Ischemic post?conditioning can alleviate free radical injury and inflammation caused by I/R injury.

[Effect of different time windows and interventions on skin pressure ulcers and ischemia-reperfusion injury in rats]

OBJECTIVE

To observe the effect of different time windows and interventions on skin pressure ulcers and ischemia-reperfusion (I/R) injury in rats.

METHODS

Sixty?eight SD rats were randomly divided into blank control group (n=4) and model group (n=64). The rats in the model group were randomly divided into group A (n=32) without intervention and group B (n=32) with post?conditioning. The degree of skin compression, neutrophil infiltration and serum levels of free radicals were observed in the rats after compression for 2, 4, 6, and 8 h (8 rats at each time point).

RESULTS

A significant difference was found in the severity of skin damage among the control group, group A, and group B (P=0.001), and the injury was milder in group B than in group A. Severe skin lesions occurred in 2 rats after skin compression for 6 h, as compared with 6 after compression for 8 h (P=0.043), but in none of the rats after compression for 2 or 4. Seventeen rats in group B and 15 in group A showed grade 1 neutrophil infiltration in the skin lesions, and 8 rats in group B and 10 in group A showed grade II neutrophil infiltration (P=0.002). Neutrophil infiltration was the mildest in rats with a 2?h compression, and exacerbated progressively and significantly as the compression time extended (P=0.027). With the prolongation of the intervention time, the rats in both groups A and B showed decreased SOD and increased MDA and NO levels, and overall the I/R injury was milder in 2? and 4?h compression groups than in 6? and 8?h compression groups. The level of serum SOD was significantly higher and MDA and NO levels were significantly higher in group B than in group A (P<0.05).

CONCLUSION

Ischemic post?conditioning can relieve I/R injury in acute pressure ulcer in rats. The effective time window for intervention is within 6 h of ischemia, and the effect of ischemic post-conditioning is optimal within 2 h. Ischemic post?conditioning can alleviate free radical injury and inflammation caused by I/R injury.