Liposomal SDF-1 Alpha Delivery in Nanocomposite Hydrogels Promotes Macrophage Phenotype Changes and Skin Tissue Regeneration

Modulating the immune system towards a functional chronic wound healing: A biomaterials and Nanomedicine perspective

Chronic non-healing wounds persist as a substantial burden for healthcare systems, influenced by factors such as aging, diabetes, and obesity. In contrast to the traditionally pro-regenerative emphasis of therapies, the recognition of the immune system integral role in wound healing has significantly grown, instigating an approach shift towards immunological processes. Thus, this review explores the wound healing process, highlighting the engagement of the immune system, and delving into the behaviors of innate and adaptive immune cells in chronic wound scenarios. Moreover, the article investigates biomaterial-based strategies for the modulation of the immune system, elucidating how the adjustment of their physicochemical properties or their synergistic combination with other agents such as drugs, proteins or mesenchymal stromal cells can effectively modulate the behaviors of different immune cells. Finally this review explores various strategies based on synthetic and biological nanostructures, including extracellular vesicles, to finely tune the immune system as natural immunomodulators or therapeutic nanocarriers with promising biophysical properties.

Multifunctional Drug- and AuNRs-Loaded ROS-Responsive Selenium-Containing Polyurethane Nanofibers for Smart Wound Healing

Elevated levels of ROS, bacterial infection, inflammation, and improper regeneration are the factors that need to be addressed simultaneously for achieving effective wound healing without scar formation. This study focuses on the fabrication of electrospun ROS-responsive selenium-containing polyurethane nanofibers incorporating deferoxamine mesylate (Def), indomethacin (Indo), and gold nanorods (AuNRs) as proangiogenesis, anti-inflammatory, and antibacterial agents for synchronized delivery to a full-thickness wound in vivo. The structure of the fabricated nanofibers was analyzed by various techniques. Toxicity was checked by CCK-8 and hemolytic assays. The efficiency of wound healing in vitro was verified by a transwell assay and cell scratch assay. The wound healing efficiency of the nanofibers was assayed in full-thickness wounds in a rat model. The multifunctional nanofibers had a porous structure, enhanced antioxidation, antibacterial activity, and promoted wound healing. They eradicated TNF-α and IL-6, increased IL-10 expression, and revealed the angiogenic potential by increased expression of HIF-1α, VEGF, and CD31.

Liposome-integrated hydrogel hybrids: Promising platforms for cancer therapy and tissue regeneration

Drug delivery platforms have gracefully emerged as an indispensable component of novel cancer chemotherapy, bestowing targeted drug distribution, elevating therapeutic effects, and reducing the burden of unwanted side effects. In this context, hybrid delivery systems artfully harnessing the virtues of liposomes and hydrogels bring remarkable benefits, especially for localized cancer therapy, including intensified stability, excellent amenability to hydrophobic and hydrophilic medications, controlled liberation behavior, and appropriate mucoadhesion to mucopenetration shift. Moreover, three-dimensional biocompatible liposome-integrated hydrogel networks have attracted unprecedented interest in tissue regeneration, given their tunable architecture and physicochemical properties, as well as enhanced mechanical support. This review elucidates and presents cutting-edge developments in recruiting liposome-integrated hydrogel systems for cancer treatment and tissue regeneration.

Nanocomposite Hydrogels-A Promising Approach towards Enhanced Bioavailability and Controlled Drug Delivery

Nanotechnology has emerged as the eminent focus of today's research to overcome challenges related to conventional drug delivery systems. A wide spectrum of novel delivery systems has been investigated to improve the therapeutic outcomes of drugs. The polymer-based nanocomposite hydrogels (NCHs) that have evolved as efficient carriers for controlled drug delivery are of particular interest in this regard. Nanocomposites amalgamate the properties of both nanoparticles (NPs) as well as hydrogels, exhibiting superior functionalities over conventional hydrogels. This multiple functionality is based upon advanced mechanical, electrical, optical as well as magnetic properties. Here is a brief overview of the various types of nanocomposites, such as NCHs based on Carbon-bearing nanomaterials, polymeric nanoparticles, inorganic nanoparticles, and metal and metal-oxide NPs. Accordingly, this article will review numerous ways of preparing these NCHs with particular emphasis on the vast biomedical applications displayed by them in numerous fields such as tissue engineering, drug delivery, wound healing, bioprinting, biosensing, imaging and gene silencing, cancer therapy, antibacterial therapy, etc. Moreover, various features can be tuned, based on the final application, by controlling the chemical composition of hydrogel network, which may also influence the released conduct. Subsequently, the recent work and future prospects of this newly emerging class of drug delivery system have been enlisted.

Enhancing angiogenesis: Innovative drug delivery systems to facilitate diabetic wound healing

Diabetic wounds (DW) constitute a substantial burden on global healthcare owing to their widespread occurrence as a complication of diabetes. Angiogenesis, a crucial process, plays a pivotal role in tissue recovery by supplying essential oxygen and nutrients to the injury site. Unfortunately, in diabetes mellitus, various factors disrupt angiogenesis, hindering wound healing. While biomaterials designed to enhance angiogenesis hold promise for the treatment of DWs, there is an urgent need for more in-depth investigations to fully unlock their potential in clinical management. In this review, we explore the intricate mechanisms of angiogenesis that are crucial for DW recovery. We introduce a rational design for angiogenesis-enhancing drug delivery systems (DDS) and provide a comprehensive summary and discussion of diverse biomaterials that enhance angiogenesis for facilitating DW healing. Lastly, we address emerging challenges and prospects in angiogenesis-enhancing DDS for facilitating DW healing, aiming to offer a comprehensive understanding of this critical healthcare issue and potential solutions.

Harnessing strategies for enhancing diabetic wound healing from the perspective of spatial inflammation patterns

Diabetic wound is a great threat to patient's health and lives. The refractory diabetic wound shows spatial inflammation patterns, in which the early-wound pattern depicts a deprived acute inflammatory response, and the long-term non-healing wound pattern delineates an excessive and persistent inflammation due to the delayed immune cell infiltration in a positive feedback loop. In this work, we give points to some strategies to normalize the dysregulated immune process based on the spatial inflammation pattern differences in diabetic wound healing. First of all, inhibiting inflammatory response to avoid subsequent persistent and excessive immune infiltration for the early diabetic wound is proposed. However, diabetic wounds are unperceptive trauma that makes patients miss the best treatment time. Therefore, we also introduce two strategies for the long-term non-healing diabetic wound. One strategy is about changing chronic wounds to acute ones, which aims to rejuvenate M1 macrophages in diabetic wounds and make spontaneous M2 polarization possible. To activate the controllable proinflammatory response, western medicine delivers proinflammatory molecules while traditional Chinese medicine develops "wound-pus promoting granulation tissue growth theory". Another strategy to solve long-term non-healing wounds is seeking switches that target M1/M2 transition directly. These investigations draw a map that delineates strategies for enhancing diabetic wound healing from the perspective of spatial inflammation patterns systematically.

Modulation of Macrophage Function by Bioactive Wound Dressings with an Emphasis on Extracellular Matrix-Based Scaffolds and Nanofibrous Composites

Bioactive wound dressings that are capable of regulating the local wound microenvironment have attracted a very large interest in the field of regenerative medicine. Macrophages have many critical roles in normal wound healing, and the dysfunction of macrophages significantly contributes to impaired or non-healing skin wounds. Regulation of macrophage polarization towards an M2 phenotype provides a feasible strategy to enhance chronic wound healing, mainly by promoting the transition of chronic inflammation to the proliferation phase of wound healing, upregulating the level of anti-inflammatory cytokines around the wound area, and stimulating wound angiogenesis and re-epithelialization. Based on this, modulation of macrophage functions by the rational design of bioactive scaffolds has emerged as a promising way to accelerate delayed wound healing. This review outlines current strategies to regulate the response of macrophages using bioactive materials, with an emphasis on extracellular matrix-based scaffolds and nanofibrous composites.

The Effect of Dosing of Stromal Cell-Derived Factor 1 on Anal Sphincter Regeneration

Aim: The aim of this study is to investigate if a high dose of the stromal cell-derived factor-1 (SDF-1) plasmid improves outcome in a minipig model of chronic anal sphincter injury. Methods: Twenty-two female minipigs underwent excision of the posterior hemicircumference of the anal sphincter complex and were allowed to recover for 6 weeks. They were randomly allocated (n = 6) to receive either 5% dextrose (sham) or 2, 4, or 8 mg of SDF-1 plasmid at the defect site. Two control pigs received no surgery/treatment. Outcome measures included anal manometry at preinjury/pretreatment and 2, 4, and 8 weeks after treatment, recording the mean of eight pressure channels and the posterior channel alone, histopathology using Masson's trichrome, and immunohistochemistry using PGP9.5 for staining of neural structures, and CY3 staining for blood vessels. Data are expressed as mean ± standard error. Manometry analysis used two-way analysis of variance (ANOVA) followed by the Holm-Sidak test. Quantification of muscle/fibrosis was analyzed with a Kruskal-Wallis one-way ANOVA on ranks. Results: Posterior anal pressures were significantly decreased in sham treated animals compared with controls (p = 0.04). In contrast, mean anal pressures at the four time points were not significantly different between groups (p > 0.05). The defect area of the sham treated group showed irregular muscle bundles, while all three SDF-1 treatment groups show organized muscle bundles, with the most organization in the higher dose groups. Quantification of Masson-stained slides showed no statistically significant differences between groups, but did show increased muscle volume in the area of defect in the treatment groups compared with sham. PGP9.5 and CY3 staining showed increased fluorescence in the higher dose groups compared with sham treatment. Conclusion: A single higher dose of the plasmid encoding SDF-1 may increase muscle volume in the area of a chronic defect. Impact statement Fecal or bowel incontinence as a result of a torn anal sphincter complex remains undetected for many years. The resulting defect does not respond well to surgical repair. Regenerating the anal sphincter complex with functional muscle has been a long-term goal. Stem cells home to a site of a chronic injury and cause regeneration when a cell signaling mechanism is available. Stromal cell-derived factor-1 is one such cytokine that has been well researched by us and others to have this effect. It is easy to use clinically and has been used in other applications in humans and considered safe.

Biomembrane-Based Nanostructure- and Microstructure-Loaded Hydrogels for Promoting Chronic Wound Healing

Wound healing is a complex and dynamic process, and metabolic disturbances in the microenvironment of chronic wounds and the severe symptoms they cause remain major challenges to be addressed. The inherent properties of hydrogels make them promising wound dressings. In addition, biomembrane-based nanostructures and microstructures (such as liposomes, exosomes, membrane-coated nanostructures, bacteria and algae) have significant advantages in the promotion of wound healing, including special biological activities, flexible drug loading and targeting. Therefore, biomembrane-based nanostructure- and microstructure-loaded hydrogels can compensate for their respective disadvantages and combine the advantages of both to significantly promote chronic wound healing. In this review, we outline the loading strategies, mechanisms of action and applications of different types of biomembrane-based nanostructure- and microstructure-loaded hydrogels in chronic wound healing.

Localized Delivery of Bioactives using Structured Liposomal Gels

Liposomes have gained a lot of interest for drug delivery applications, and some of these preparations have been commercialized. These are formulated with biocompatible components and can be used for delivering a wide range of payloads differing in aqueous solubility and molecular weight. Liposome-based delivery approaches are limited mainly by two factors: (a) poor dispersion stability, and (b) pre-mature leakage of payloads. In this review, we have discussed the stabilization of liposomal vesicles by their entrapment in hydrogels. Studies reveal that such hydrogels can maintain the structural integrity of liposomes. Release of liposomes from the hydrogel network can be modulated through careful screening of matrix former and degree of its cross-linking. Accordingly, we have reviewed the approaches of stabilizing liposomal vesicles through entrapment in hydrogels. Application of liposome-embedded hydrogels has been reviewed in context of localized drug delivery. Our discussion is focussed on the delivery of bioactives to the skin. Such an approach appears alluring from the standpoint of minimizing the undesirable distribution of payload(s) the systemic circulation and off-target sites.

Recent advances of the nanocomposite hydrogel as a local drug delivery for diabetic ulcers

Diabetic ulcer is a serious complication of diabetes. Compared with that of healthy people, the skin of patients with a diabetic ulcer is more easily damaged and difficult to heal. Without early intervention, the disease will become increasingly serious, often leading to amputation or even death. Most current treatment methods cannot achieve a good wound healing effect. Numerous studies have shown that a nanocomposite hydrogel serves as an ideal drug delivery method to promote the healing of a diabetic ulcer because of its better drug loading capacity and stability. Nanocomposite hydrogels can be loaded with one or more drugs for application to chronic ulcer wounds to promote rapid wound healing. Therefore, this paper reviews the latest progress of delivery systems based on nanocomposite hydrogels in promoting diabetic ulcer healing. Through a review of the recent literature, we put forward the shortcomings and improvement strategies of nanocomposite hydrogels in the treatment of diabetic ulcers.

FTY720 administration results in a M2 associated immunoregulatory effect that positively influences the outcome of alveolar bone repair outcome in mice

The alveolar bone repair process may be influenced by multiple local and systemic factors, which include immune system cells and mediators. Macrophages allegedly play important roles in the repair process, and the transition of an initial inflammatory M1 profile into a pro-reparative M2 profile theoretically contributes to a favorable repair outcome. In this context, considering immunoregulatory molecules as potential targets for improving bone repair, this study evaluated the role of the immunoregulatory molecule FTY720, previously described to favor the development of the M2 phenotype, in the process of alveolar bone healing in C57Bl/6 (WT) mice. Experimental groups submitted to tooth extraction and maintained under control conditions or treated with FTY720 were evaluated by microtomographic (μCT), histomorphometric, immunohistochemical and molecular analysis to characterize healing and host response features at 0, 1, 3, 7 and 14 days. Our results demonstrated that the FTY720 group presented higher bone tissue density, higher bone tissue volume, greater tissue volume fraction, greater number and thickness of trabeculae and a higher number of osteoblasts and osteoclasts than the control group. Accordingly, the bone markers BMP2, BMP7, ALPL, SOST and RANK mRNA expressions increased in the FTY720 treated group. Furthermore, the levels of FIZZ, ARG2 and IL-10 mRNA increased in the FTY720 group together with the presence of CD206⁺ cells, suggesting that the boost of bone formation mediated by FTY720 involves an increased polarization and activity of M2 macrophages in healing sites. Thus, our results demonstrate that FTY720 favored the process of alveolar bone repair, probably trough a strengthened M2 response, associated with an increased expression of markers osteogenic differentiation and activity markers. Immunoregulatory strategies based in the modulation of macrophage polarization profile can comprise effective tools to improve the bone repair process.

SDF-1 Functionalized Hydrogel Microcarriers for Skin Flap Repair

Critically sized skin flaps used to treat skin defects often suffer from necrosis due to insufficient blood supply. Hence there is an urgent need to improve the survival rate of skin flaps by promoting local angiogenesis. The delivery of growth factor loaded microcarriers have shown promise in enhancing defect repair, however, their rapid clearance from the defect site limits their regenerative potential. Thus, it is critical to develop microcarriers which can promote the sustained release of bioactive factors to effectively stimulate tissue repair. This study aimed to develop a stromal cell-derived factor 1 (SDF-1) loaded microcarrier coated with Matrigel (MC@SDF-1@Mat) to promote skin flap repair. SEM imaging showed that the surface of the microcarrier was coated by a porous Matrigel film. The drug release experiment showed that the Matrigel-coated microcarriers enhanced the sustained release of the model drug methylene blue when compared to uncoated group. MC@SDF-1@Mat significantly promoted the proliferation, migration, and angiogenesis of HUVECs via CCK-8, wound healing assay, and tube formation assay, respectively. Moreover, the murine random skin flap model was further established and treated. It was found that the flap necrosis area in the MC@SDF-1@Mat treated group was significantly reduced. H&E and Masson staining showed the histological structure and collagen organization exhibited a normal phenotype in the MC@SDF-1@Mat treated group. Additionally, CD31 immunohistochemical analysis showed that the MC@SDF-1@Mat treated group exhibited the greatest degree of neovascularization. In conclusion, our SDF-1 functionalized gelatin-based hydrogel microcarrier has potential clinical applications in promoting skin flap repair and drug delivery.

Rational design of flexible microneedles coupled with CaO2@PDA-loaded nanofiber films for skin wound healing on diabetic rats

Skin ulcers is one of the complications of diabetes. At present, the treatment of diabetic skin wound is still not satisfactory, and the efficiency of drug delivery is limited by the depth...