Simultaneous regulation of AGE/RAGE signaling and MMP-9 expression by an immunomodulating hydrogel accelerates healing in diabetic wounds.

PURPOSE: In chronic hyperglycemia, the advanced glycation end product (AGE) interacts with its receptor (RAGE) and contributes to impaired wound healing by inducing oxidative stress, generating dysfunctional macrophages, and prolonging the inflammatory response. Additionally, uncontrolled levels of proteases, including metallomatrix protease-9 (MMP-9), in the diabetic wound bed degrade the extracellular matrix (ECM) and biological cues that augment healing. A multifunctional antimicrobial hydrogel (Immuno-gel) containing RAGE and MMP-9 inhibitors can regulate the wound microenvironment and promote scar-free healing. RESULTS: Immuno-gel was characterized and the wound healing efficacy was determined in vitro cell culture and in vivo diabetic Wistar rat wound model using ELISA, Western blot, and Immunofluorescence staining. The Immuno-gel exhibited a highly porous morphology with excellent in vitro cytocompatibility. AGE-stimulated macrophages treated with the Immuno-gel released higher levels of pro-healing cytokines in vitro. In the hydrogel-wound interface of diabetic Wistar rats, Immuno-gel treatment significantly reduced MMP-9 and NF-κB expression and enhanced pro-healing (M2) macrophage population and pro-healing cytokines. CONCLUSION: Altogether, this study suggests that Immuno-gel simultaneously attenuates macrophage dysfunction through the inhibition of AGE/RAGE signaling and reduces MMP-9 overexpression, both of which favor scar-free healing. The combinatorial treatment with RAGE and MMP-9 inhibitors via Immuno-gel simultaneously modulates the diabetic wound microenvironment, making it a promising novel treatment to accelerate diabetic wound healing.

A multifunctional silk-hyaluronic acid self-healing hydrogel laden with alternatively activated macrophage-derived exosomes reshape microenvironment of diabetic wound and accelerate healing.

The impairment of phenotype switching of pro-inflammatory M1 to pro-healing M2 macrophage induced by hyperglycemic microenvironment often elevates oxidative stress, impairs angiogenesis, and leads to chronic non-healing wounds in diabetic patients. Administration of M2 macrophage-derived exosomes (M2Exo) at wound site is known to polarize M1 to M2 macrophage and can accelerate wound healing by enhancing collagen deposition, angiogenesis, and re-epithelialization. In the present study, M2Exo were conjugated with oxidized hyaluronic acid and mixed with PEGylated silk fibroin to develop self-healing Exo-gel to achieve an efficient therapy for diabetic wounds. Exo-gel depicted porous networked morphology with self-healing and excellent water retention behaviour. Fibroblast cells treated with Exo-gel showed significant uptake of M2Exo that increased their proliferation and migration in vitro. Interestingly, in a diabetic wound model of wistar rats, Exo-gel treatment induced 75 % wound closure within 7 days with complete epithelial layer regeneration by modulating cytokine levels, stimulating fibroblast-keratinocyte interaction and migration, angiogenesis, and organized collagen deposition. Taken together, this study suggests that Exo-gel depict properties of an excellent wound healing matrix and can be used as a therapeutic alternative to treat chronic non-healing diabetic wounds.

Structurally stable and surface-textured polylactic acid/copolymer/poly (ε-caprolactone) blend-based electrospun constructs with tunable hydroxyapatite responsiveness.

Functionally-designed nanotextured and copolymer (COP) mediated PLA/PCL (70:30 w/w) blend-based interface-engineered electrospun mats (EMs) based constructs, with phase-specific interactions, have been successfully developed. The thermal stability of constructs remained up to ∼300-350 °C, while the crystallinity reduced to ∼12-23 %, indicating enhanced pliability. The tensile strength increased by ∼75 % without much compromise in the tensile modulus whereas the dynamic relaxation response of the constructs shifted to lower temperatures upon the incorporation of ≥ 2.5 phr (parts per hundred parts of resin) of COP. The zeta potential evaluated from radial surface exposure intensity could be manipulated by controlling the extent of COP content (-60 mV for ∼5 phr COP) which in turn led to the dynamics of site-specific charge neutralization driven attachment of Ca2+ ions (∼13 % for ∼5 phr COP) of the nano-hydroxyapatite (n-HA). Such uniformly dispersed, n-HA attached, and surface-decorated (COP ≤ 5 phr) EMs enabled the selective L929 fibroblast cell attachment (∼200 % cell viability for ∼2.5 phr COP). Thus, the approach may prove to augment the biomineralization of Ca and apatite-driven healing kinetics amongst implant-seeking and inflammation-prone sites and thereby, paving a new pathway for controlled and targeted healing of bone, cartilage, dental gums, and other sites demanding n-HA and/or calcium-phosphorus assisted healing mechanism.

Recombinant protein polymers as carriers of chemotherapeutic agents.

Chemotherapy is the standard of care for the treatment of cancer and infectious diseases. However, its use is associated with severe toxicity and resistance arising mainly due to non-specificity, resulting in disease progression. The advancement in recombinant technology has led to the synthesis of genetically engineered protein polymers like Elastin-like polypeptide (ELP), Silk-like polypeptide (SLP), hybrid protein polymers with specific sequences to impart precisely controlled properties and to target proteins that have provided satisfactory preclinical outcomes. Such protein polymers have been exploited for the formulation and delivery of chemotherapeutics for biomedical applications. The use of such polymers has not only solved the limitation of conventional chemotherapy but has also improved the therapeutic index of typical drug delivery systems. This review, therefore, summarizes the development of such advanced recombinant protein polymers designed to deliver chemotherapeutics and also discusses the key challenges associated with their current usage and their application in the future.

Designing suture-proof cell-attachable copolymer-mediated and curcumin- ß-cyclodextrin inclusion complex loaded aliphatic polyester-based electrospun antibacterial constructs.

The paper demonstrates curcumin/ß-cyclodextrin-based inclusion complex (IC) loaded polyvinyl alcohol (PVA) dip-coated and copolymer-compatibilized polylactic acid (PLA)/poly(ε-caprolactone) (PCL) blend-based electrospun mats (EMs) as antibacterial, and suture-resistant constructs, to overcome the present challenges in developing structurally-stable, biocompatible, pliable, and stand-alone multifunctional-biomedical-devices. The thermal, microstructural, and viscoelastic characterization confirmed the presence of H-bonding interactions between IC and PVA moieties and between IC incorporated PVA matrix with the copolymer-mediated nanotextured PLA/PCL blend-based EMs. IC release and surface PVA erosion induced a decrease in modulus (>4-fold) and strength (>2-fold) of constructs (post-release). Mechanistically new and architectural-framework-defined PVA-gelation induced bi-axially diverted suture-failure (post-release) and resulted in a significant enhancement in suture-retention-strength (>3-fold), energy (>5-fold), and displacement (>2-fold) for ~20 wt% IC-loaded-PVA-coated EM-constructs. The fabricated EM-constructs exhibited improvement in surface-hydrophilicity (contact angle ~45°), surface nano-roughness (~ 600 nm), surface area (~34 m2/g), pore volume (~3.6 × 10-2 cc/g), IC release efficacy (~20 % burst release), antibacterial activity (adherent bacteria <10 %) against E. coli and S. aureus, and L929 fibroblast-cell-viability (~135 %), which varied as a function of IC-content in the PVA matrix. Our study conceptually establishes a novel and efficient technique for designing antibacterial, suture-resistant engineered-EM-constructs with tunable properties for their potential use in wound-dressings, periodontal-membranes, drug-delivery, and regenerative-systems.

Fabrication of In Situ Layered Hydrogel Scaffold for the Co-delivery of PGDF-BB/Chlorhexidine to Regulate Proinflammatory Cytokines, Growth Factors, and MMP-9 in a Diabetic Skin Defect Albino Rat Model.

Diabetes mellitus (DM)-associated impairments in wound healing include prolonged inflammation, the overexpression of matrix metalloproteases (MMPs), and low levels of growth factors at the wound site. To this end, a layer-by-layer scaffold (SL-B-L) made of cross-linked silk fibroin and hyaluronic acid is developed to deliver chlorhexidine, an antimicrobial agent and an MMP-9 inhibitor, along with the PDGF-BB protein. SL-B-L exhibited highly porous morphology. Diabetic rats treated with SL-B-L demonstrated an early wound closure, a fully reconstructed epithelial layer by 14 days, and reduced levels of IL-6, TNF-α, TGF-ß1, and MMP-9. Interestingly, SL-B-L treatment increased angiogenesis, the bioavailability of collagen, DNA content, and VEGF-A levels. Furthermore, enhanced keratinocyte-fibroblast interaction along with ordered collagen deposition was observed in SL-B-L-treated rats. Most interestingly, when compared with a clinically used scaffold SEESKIN+, SL-B-L outperformed in promoting wound healing in a diabetic rat model by regulating the inflammation while delivering growth factor and the MMP-9 inhibitor.