A major challenge in chronic wound treatment is maintaining an appropriate wound moisture balance throughout the healing process. Wound dehydration hinders wound healing due to impeded molecule ...transport and cell migration with associated tissue necrosis. In contrast, wounds that produce excess fluid contain high levels of reactive oxygen species and matrix metalloproteases that impede cell recruitment, extracellular matrix reconstruction, and angiogenesis. Dressings are currently selected based on the relative amount of wound exudate with no universal dressing available that can maintain appropriate wound moisture balance to enhance healing. This work aimed to develop a high porosity poly(ethylene glycol) diacrylate hydrogel foam that can both rapidly remove exudate and provide self‐tuning moisture control to prevent wound dehydration. A custom foaming device was used to vary hydrogel foam porosity from 25% to 75% by adjusting the initial air‐to‐solution volume ratio. Hydrogel foams demonstrated substantial improvements in water uptake volume and rate as compared to bulk hydrogels while maintaining similar hydration benefits with slow dehydration rates. The hydrogel foam with the highest porosity (~75%) demonstrated the greatest water uptake and rate, which outperformed commercial dressing products, Curafoam® and Silvercel®, in water absorption, moisture retention, and exudate management. Investigation of the water vapor transmission rates of each dressing at varied hydration levels was characterized and demonstrated the dynamic moisture‐controlling capability of the hydrogel foam dressing. Overall, the self‐tuning moisture control of this hydrogel foam dressing holds great promise to improve healing outcomes for both dry and exudative chronic wounds.
Emulsion Inks for 3D Printing of High Porosity Materials Sears, Nicholas A.; Dhavalikar, Prachi S.; Cosgriff-Hernandez, Elizabeth M.
Macromolecular rapid communications.,
August 2016, Letnik:
37, Številka:
16
Journal Article
Recenzirano
Photocurable emulsion inks for use with solid freeform fabrication (SFF) to generate constructs with hierarchical porosity are presented. A high internal phase emulsion (HIPE) templating technique ...was utilized to prepare water‐in‐oil emulsions from a hydrophobic photopolymer, surfactant, and water. These HIPEs displayed strong shear thinning behavior that permitted layer‐by‐layer deposition into complex shapes and adequately high viscosity at low shear for shape retention after extrusion. Each layer was actively polymerized with an ultraviolet cure‐on‐dispense (CoD) technique and compositions with sufficient viscosity were able to produce tall, complex scaffolds with an internal lattice structure and microscale porosity. Evaluation of the rheological and cure properties indicated that the viscosity and cure rate both played an important role in print fidelity. These 3D printed polyHIPE constructs benefit from the tunable pore structure of emulsion templated material and the designed architecture of 3D printing. As such, these emulsion inks can be used to create ultra high porosity constructs with complex geometries and internal lattice structures not possible with traditional manufacturing techniques.
Emulsion inks for 3D printing high porosity foams using cure‐on‐dispense technology have been developed. Complex, self‐supporting shapes were fabricated using photocurable emulsion inks based on high internal phase emulsions with solid freeform fabrication. Successful inks possessed high viscosity, strong shear thinning behavior, and rapid cure. High fidelity prints displayed tunable microscale porosity, internal lattice structures, and complex geometries.
Stem cell therapy and skin substitutes address the stalled healing of chronic wounds in order to promote wound closure; however, the high cost and regulatory hurdles of these treatments limit patient ...access. A low‐cost method to induce bioactive healing has the potential to substantially improve patient care and prevent wound‐induced limb loss. A previous study reported that bioactive factors derived from apoptotic‐like mesenchymal stem cells (MSCs) demonstrated anti‐inflammatory and proangiogenic effects and improved ischemic muscle regeneration. In this work, these MSC‐derived bioactive factors were loaded into a hydrogel foam to harness immunomodulatory and angiogenic properties from MSC components to facilitate chronic wound healing without the high cost and translational challenges of cell therapies. After incorporation of bioactive factors, the hydrogel foam retained high absorbency, moisture retention, and target water vapor transmission rate. High loading efficiency was confirmed and release studies indicated that over 90% of loaded factors were released within 24 h. Ethylene oxide sterilization and 4‐week storage did not affect the bioactive factor release profile or physical properties of the hydrogel foam dressing. Bioactivity retention of the released factors was also confirmed for as‐sterilized, 4°C‐stored, and −20°C‐stored bioactive hydrogel foams as determined by relevant gene expression levels in treated pro‐inflammatory (M1) macrophages. These results support the use of the bioactive dressings as an off‐the‐shelf product. Overall, this work reports a new method to achieve a first‐line wound dressing with the potential to reduce persistent inflammation and promote angiogenesis in chronic wounds.
Purpose
Integrating mHealth into the cancer care continuum may be an effective strategy to improve cancer survivorship care by supporting self-management. We aim to assess the effectiveness of ...mHealth applications (apps) for self-management in improving pain, psychological distress, fatigue, or sleep outcomes in adult cancer survivors.
Methods
Experimental quantitative studies evaluating apps aiming to support self-management for adult cancer survivors and reporting pain, psychological distress, fatigue, or sleep outcomes were included. PubMed, Web of Science, Embase, CINAHL, PsycINFO, Scopus, and CENTRAL databases were searched from inception through December 2017. Risk of bias was assessed using the Cochrane risk of bias tool (PROSPERO registration number CRD42017081182).
Results
Seven studies of six mHealth interventions (
n
= 949 participants) were included. Two randomized controlled trials (RCTs), one quasi-RCT, one non-RCT, and three single-arm studies involved survivors with a mix of cancer types. The most common app features were symptom questionnaires (
n
= 5) and progress tracking (
n
= 5). Four studies reported outcomes for pain, with three showing improvements. Two studies reported psychological distress outcomes, showing mixed results. Four studies reported improvements in fatigue post-intervention or in the intervention compared with control group, but the changes were not all statistically significant. Two studies reported improvements in sleep outcomes.
Conclusions
There is emerging evidence that mHealth interventions that support self-management can improve pain and fatigue outcomes in cancer survivors, and some promise for psychological distress and sleep outcomes. Further development and investigation of mHealth is needed, incorporating targeted, evidence-based models of care into app design.
Implications for Cancer Survivors
mHealth interventions can improve outcomes for cancer survivors and have significant potential to benefit this growing population due to their reach.
Poly(ethylene glycol) (PEG)‐based hydrogels have gained significant attention in the field of biomedical applications due to their versatility and antifouling properties. Acrylate‐derivatized PEG ...hydrogels (PEGDA) are some of the most widely studied hydrogels; however, there has been debate around the degradation mechanism and predicting resorption rates. Several factors influence the degradation rate of PEG hydrogels, including backbone and endgroup chemistry, macromer molecular weight, and polymer concentration. In addition to hydrogel parameters, it is necessary to understand the influence of biological and environmental conditions (e.g., pH and temperature) on hydrogel degradation. Rigorous methods for monitoring degradation in both in vitro and in vivo settings are also critical to hydrogel design and development. Herein, we provide guidance on tailoring PEG hydrogel chemistry to achieve target hydrolytic degradation kinetics for both resorbable and biostable applications. A detailed overview of accelerated testing methods and hydrogel degradation characterization is provided to aid researchers in experimental design and interpreting in vitro–in vivo correlations necessary for predicting hydrogel device performance.
PolyHIPEs, highly porous polymers synthesized within high internal phase emulsions (HIPEs), emulsions with over 74% internal phase, are of interest for applications such as absorbents, reaction ...supports, and tissue engineering scaffolds. Typically, the surfactant contents for HIPE stabilization are relatively high, ranging from 20 to 30 wt% of the external phase, with the monomers usually being the remainder. One drawback of using surfactants for these applications is the potential for leachables, necessitating intensive purification processes for their removal. Pickering HIPEs, HIPEs stabilized using amphiphilic solid nanoparticles that spontaneously migrate to the oil–water interface, can be used as an alternative HIPE stabilization strategy. Although nanoparticles can add surface functionality advantageous for the application, polyHIPEs from Pickering HIPEs often lack the interconnecting holes needed for the high permeability required for such applications. This work describes a successful approach for designing an HIPE stabilization system that is based on a combination of nanoparticles and reactive surfactants and that generates the desired surface functionality, an interconnected porous structure, and a low leachable content. Such an approach can extend the applicative utility of such polyHIPEs by circumventing the need for extensive purification.
PolyHIPEs, porous polymers synthesized within high internal phase emulsions (HIPEs), are of interest for absorbent, reaction support, and tissue engineering applications. Unfortunately, nanoparticle stabilization produces closed‐cell structures, while surfactant stabilization produces a high leachable content. This successful approach for HIPE stabilization combines functionalized nanoparticles and reactive surfactants to generate an open‐cell structure with nanoparticle‐covered surfaces and a low leachable content.
Polymeric heart valves offer the potential to overcome the limited durability of tissue based bioprosthetic valves and the need for anticoagulant therapy of mechanical valve replacement options. ...However, developing a single‐phase material with requisite biological properties and target mechanical properties remains a challenge. In this study, a composite heart valve material was developed where an electrospun mesh provides tunable mechanical properties and a hydrogel coating confers an antifouling surface for thromboresistance. Key biological responses were evaluated in comparison to glutaraldehyde‐fixed pericardium. Platelet and bacterial attachment were reduced by 38% and 98%, respectively, as compared to pericardium that demonstrated the antifouling nature of the hydrogel coating. There was also a notable reduction (59%) in the calcification of the composite material as compared to pericardium. A custom 3D‐printed hydrogel coating setup was developed to make valve composites for device‐level hemodynamic testing. Regurgitation fraction (9.6 ± 1.8%) and effective orifice area (1.52 ± 0.34 cm2) met ISO 5840‐2:2021 requirements. Additionally, the mean pressure gradient was comparable to current clinical bioprosthetic heart valves demonstrating preliminary efficacy. Although the hemodynamic properties are promising, it is anticipated that the random microarchitecture will result in suboptimal strain fields and peak stresses that may accelerate leaflet fatigue and degeneration. Previous computational work has demonstrated that bioinspired fiber microarchitectures can improve strain homogeneity of valve materials toward improving durability. To this end, we developed advanced electrospinning methodologies to achieve polyurethane fiber microarchitectures that mimic or exceed the physiological ranges of alignment, tortuosity, and curvilinearity present in the native valve. Control of fiber alignment from a random fiber orientation at a normalized orientation index (NOI) 14.2 ± 6.9% to highly aligned fibers at a NOI of 85.1 ± 1.4%. was achieved through increasing mandrel rotational velocity. Fiber tortuosity and curvilinearity in the range of native valve features were introduced through a post‐spinning annealing process and fiber collection on a conical mandrel geometry, respectively. Overall, these studies demonstrate the potential of hydrogel‐polyurethane fiber composite as a heart valve material. Future studies will utilize the developed advanced electrospinning methodologies in combination with model‐directed fabrication toward optimizing durability as a function of fiber microarchitecture.
Gelatin Matrices for Growth Factor Sequestration Buie, Taneidra; McCune, Joshua; Cosgriff-Hernandez, Elizabeth
Trends in biotechnology (Regular ed.),
20/May , Letnik:
38, Številka:
5
Journal Article
Recenzirano
Gelatin is used in a broad range of tissue engineering applications because of its bioactivity, mild processing conditions, and ease of modification, which have increased interest in its use as a ...growth factor delivery vehicle. Traditional methods to control growth factor sequestration and delivery have relied on controlling hydrogel mesh size via chemical crosslinking with corollary changes to the physical properties of the hydrogel. To decouple growth factor release from scaffold properties, affinity sequestration modalities have been developed to preserve the bioactivity of the growth factor through interactions with the modified gelatin. This review provides a summary of these mechanisms, highlights current gelatin growth factor delivery systems, and addresses the future perspective of gelatin matrices for growth factor delivery in tissue engineering.
Traditional methods of growth factor sequestration and delivery by gelatin matrices have relied on controlling hydrogel mesh size via chemical crosslinking with corollary changes to the physical properties of the hydrogel.Growth factors are generally not directly conjugated to gelatin matrices because of potential loss of bioactivity owing to non-specific reactions with amino groups.Elucidating non-covalent growth factor interactions has led to the development of affinity-based methods to increase sequestration in gelatin matrices.Modifying gelatin matrices to confer targeted growth factor affinity has potential to improve tissue regeneration over traditional crosslinking methods.
