Pluronic F-127 hydrogel as a promising scaffold for encapsulation of dental-derived mesenchymal stem cells

Exosomes derived from cord blood Treg cells promote diabetic wound healing by targeting monocytes

Chronic nonhealing diabetic wounds are a critical clinical challenge. Regulatory T cells (Tregs) are immunosuppressive modulators affecting wound healing progression by controlling the inflammatory response. The current study attempted to investigate whether the exosomes derived from cord blood (CB) Tregs can accelerate the healing process. Exosomes were isolated from CB-Treg cultures using ultracentrifugation and validated with different specific markers of exosomes. The purified CB-Treg-derived exosomes were co-cultured with peripheral blood mononuclear cells (PBMCs) and CD14+ monocytes. The migration-promoting effect of CB-Treg-derived exosomes on fibroblasts and endothelial cells was investigated. We used thermosensitive Pluronic F-127 hydrogel (PF-127) loaded with CB-Treg-derived exosomes in a diabetic wound healing mouse model. CB-Treg-derived exosomes with 30-120 nm diameters revealed exosome-specific markers, such as TSG101, Alix, and CD63. CB-Treg-derived exosomes were mainly bound to the monocytes when co-cultured with PBMCs, and promoted monocyte polarization to the anti-inflammatory phenotype (M2) in vitro. CB-Treg-derived exosomes enhanced the migration of endothelial cells and fibroblasts. Furthermore, CB-Treg-derived exosomes treatment accelerated wound healing by downregulating inflammatory factor levels and upregulating the M2 macrophage ratio in vivo. Our findings indicated that CB-Treg-derived exosomes could be a promising cell-free therapeutic strategy for diabetic wound healing, partly by targeting monocytes.

Pluronic F127 composite hydrogel for the repair of contraction suppressed full-thickness skin wounds in a rabbit model

Hydrogels are commonly used as carriers for cell delivery due to their similarities to the extracellular matrix. A contraction-suppressed full-thickness wound model was used to evaluate the therapeutic potential of Pluronic F127 (PF127) hydrogel loaded with adipose-derived stromal vascular fraction (AdSVF), mesenchymal stem cells (AdMSC), and conditioned media (AdMSC-CM) for the repair of wounds in a rabbit model. The experimental study was conducted on forty-eight healthy adult New Zealand white rabbits randomly divided into eight groups with six animals each and treated with AdSVF, AdMSC, and AdMSC-CM as an injectable or topical preparation. The healing potential of different adipose-derived cell-based and cell-free therapeutics was evaluated based on percentage wound healing, period of epithelialization, epidermal thickness, scar evaluation, histopathology analysis, histochemical evaluation, immunohistochemistry (collagen type I), and hydroxyproline assay by comparing with the positive and negative control. Collagen density analysis using different staining methods, immunohistochemistry, and hydroxyproline assay consistently showed that delivering AdMSC and AdMSC-CM in PF127 hydrogel enhanced epithelialization, collagen production, and organization, contributing to improved tissue strength and quality. Even though allogeneic AdSVF was found to promote wound healing in rabbits, it has a lower potential than AdMSC and AdMSC-CM. The wound healing potential of AdMSC and AdMSC-CM was enhanced when loaded in PF127 hydrogel and applied topically. Even though wounds treated with AdMSC outperformed AdMSC-CM, a significant difference in the healing quality was not observed in most instances, indicating almost similar therapeutic potential. The findings indicate that the wound healing potential of AdMSC and AdMSC-CM was enhanced when loaded in PF127 hydrogel and applied topically. These treatments promoted collagen production, tissue organization, and epidermal regeneration, ultimately improving overall healing outcomes.

Pluronic F127 hydrogel-loaded extracellular vesicles from adipose-derived mesenchymal stem cells promote tracheal cartilage regeneration via SCNN1B delivery

Extracellular vesicles (EVs) derived from adipose-derived mesenchymal stem cells (AMSC-EVs) have been highlighted as a cell-free therapy due to their regenerative capability to enhance tissue and organ regeneration. Herein, we aimed to examine the mechanism of PF127-hydrogel@AMSC-EVs in promoting tracheal cartilage defect repair. Based on bioinformatics methods, SCNN1B was identified as a key gene for the osteogenic differentiation of AMSCs induced by AMSC-EVs. EVs were isolated from rat AMSCs and then loaded onto thermo-sensitive PF-127 hydrogel to develop PF127-hydrogel@AMSC-EVs. It was established that PF127-hydrogel@AMSC-EVs could effectively deliver SCNN1B into AMSCs, where SCNN1B promoted AMSC osteogenic differentiation. The promotive effect was evidenced by enhanced ALP activity, extracellular matrix mineralization, and expression of s-glycosaminoglycan, RUNX2, OCN, collagen II, PERK, and ATF4. Furthermore, the in vivo experiments revealed that PF127-hydrogel@AMSC-SCNN1B-EVs stimulated tracheal cartilage regeneration in rats through PERK/ATF4 signaling axis activation. Therefore, PF127-hydrogel@AMSC-SCNN1B-EVs may be a novel cell-free biomaterial to facilitate tracheal cartilage regeneration and cartilage injury repair.

Incorporation of Resveratrol-Hydroxypropyl-β-Cyclodextrin Complexes into Hydrogel Formulation for Wound Treatment

Resveratrol could be applied in wound healing therapies because of its antioxidant, anti-inflammatory and antibacterial effects. However, the main limitation of resveratrol is its low aqueous solubility. In this study, resveratrol was included in hydroxypropyl-β-cyclodextrin complexes and further formulated in Pluronic F-127 hydrogels for wound treatment therapy. IR-spectroscopy and XRD analysis confirmed the successful incorporation of resveratrol into complexes. The wound-healing ability of these complexes was estimated by a scratch assay on fibroblasts, which showed a tendency for improvement of the effect of resveratrol after complexation. The antimicrobial activity of resveratrol in aqueous dispersion and in the complexes was evaluated on methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli, and Candida albicans strains. The results revealed a twofold decrease in the MIC and stronger inhibition of the metabolic activity of MRSA after treatment with resveratrol in the complexes compared to the suspended drug. Furthermore, the complexes were included in Pluronic hydrogel, which provided efficient drug release and appropriate viscoelastic properties. The formulated hydrogel showed excellent biocompatibility which was confirmed via skin irritation test on rabbits. In conclusion, Pluronic hydrogel containing resveratrol included in hydroxypropyl-β-cyclodextrin complexes is a promising topical formulation for further studies directed at wound therapy.

Human umbilical cord mesenchymal stem cells promote steroid-induced osteonecrosis of the femoral head repair by improving microvascular endothelial cell function

Recently, there has been growing interest in using cell therapy through core decompression (CD) to treat osteonecrosis of the femoral head (ONFH). Our study aimed to investigate the effectiveness and mechanism of human umbilical cord mesenchymal stem cells (hUCMSCs) in treating steroid-induced ONFH. We constructed a steroid-induced ONFH rabbit model as well as dexamethasone (Dex)-treated bone microvascular endothelial cells (BMECs) model of human femoral head. We injected hUCMSCs into the rabbit femoral head via CD. The effects of hUCMSCs on steroid-induced ONFH rabbit model and Dex-treated BMECs were evaluated via micro-CT, microangiography, histology, immunohistochemistry, wound healing, tube formation, and western blotting assay. Furthermore, we conducted single-cell RNA sequencing (scRNA-seq) to examine the characteristics of endothelial cells, the activation of signaling pathways, and inter-cellular communication in ONFH. Our data reveal that hUCMSCs improved the femoral head microstructure and bone repair and promoted angiogenesis in the steroid-induced ONFH rabbit model. Importantly, hUCMSCs improved the migration ability and angioplasty of Dex-treated BMECs by secreting COL6A2 to activate FAK/PI3K/AKT signaling pathway via integrin α1β1.

Structure-dynamics correlations in composite PF127-PEG-based hydrogels; cohesive/hydrophobic interactions determine phase and rheology and identify the role of micelle concentration in controlling 3D extrusion printability

A library of composite polymer networks (CPNs) were formed by combining Pluronic F127, as the primary gelator, with a range of di-acrylate functionalised PEG polymers, which tune the rheological properties and provide UV crosslinkability. A coarse-grained sol-gel room temperature phase diagram was constructed for the CPN library, which identifies PEG-dependent disruption of micelles as leading to liquefication. Small angle X-ray scattering and rheological measurements provide detailed insight into; (i) micelle-micelle ordering; (ii) micelle-micelle disruption, and; (iii) acrylate-micelle disruption; with contributions that depend on composition, including weak PEG chain length and end group effects. The influence of composition on 3D extrusion printability through modulation of the cohesive/hydrophobic interactions was assessed. It was found that only micelle content provides consistent changes in printing fidelity, controlled largely by printing conditions (pressure and feed rate). Finally, the hydrogels were shown to be UV photo-crosslinkable, which further improves fidelity and structural integrity, and usefully reduces the mesh size. Our results provide a guide for design of 3D-printable CPN inks for future biomedical applications.

Recent advances in antimicrobial peptide-based therapy

Antimicrobial peptides (AMPs) are a group of polypeptide chains that have the property to target and kill a myriad of microbial organisms including viruses, bacteria, protists, etc. The first discovered AMP was named gramicidin, an extract of aerobic soil bacteria. Further studies discovered that these peptides are present not only in prokaryotes but in eukaryotes as well. They play a vital role in human innate immunity and wound repair. Consequently, they have maintained a high level of intrigue among scientists in the field of immunology, especially so with the rise of antibiotic-resistant pathogens decreasing the reliability of antibiotics in healthcare. While AMPs have promising potential to substitute for common antibiotics, their use as effective replacements is barred by certain limitations. First, they have the potential to be cytotoxic to human cells. Second, they are unstable in the blood due to action by various proteolytic agents and ions that cause their degradation. This review provides an overview of the mechanism of AMPs, their limitations, and developments in recent years that provide techniques to overcome those limitations. We also discuss the advantages and drawbacks of AMPs as a replacement for antibiotics as compared to other alternatives such as synthetically modified bacteriophages, traditional medicine, and probiotics.

Nerve Visualization using Phenoxazine-Based Near-Infrared Fluorophores to Guide Prostatectomy

Fluorescence-guided surgery (FGS) is poised to revolutionize surgical medicine through near-infrared (NIR) fluorophores for tissue- and disease-specific contrast. Clinical open and laparoscopic FGS vision systems operate nearly exclusively at NIR wavelengths. However, tissue-specific NIR contrast agents compatible with clinically available imaging systems are lacking, leaving nerve tissue identification during prostatectomy a persistent challenge. Here, it is shown that combining drug-like molecular design concepts and fluorophore chemistry enabled the production of a library of NIR phenoxazine-based fluorophores for intraoperative nerve-specific imaging. The lead candidate readily delineated prostatic nerves in the canine and iliac plexus in the swine using the clinical da Vinci Surgical System that has been popularized for minimally invasive prostatectomy procedures. These results demonstrate the feasibility of molecular engineering of NIR nerve-binding fluorophores for ready integration into the existing surgical workflow, paving the path for clinical translation to reduce morbidity from nerve injury for prostate cancer patients.

Local Spinal Cord Injury Treatment Using a Dental Pulp Stem Cell Encapsulated H2S Releasing Multifunctional Injectable Hydrogel

Spinal cord injury (SCI) commonly induces nerve damage and nerve cell degeneration. In this work, a novel dental pulp stem cells (DPSCs) encapsulated thermoresponsive injectable hydrogel with sustained hydrogen sulfide (H2S) delivery is demonstrated for SCI repair. For controlled and sustained H2S gas therapy, a clinically tested H2S donor (JK) loaded octysilane functionalized mesoporous silica nanoparticles (OMSNs) are incorporated into the thermosensitive hydrogel made from Pluronic F127 (PF-127). The JK-loaded functionalized MSNs (OMSF@JK) promote preferential M2-like polarization of macrophages and neuronal differentiation of DPSCs in vitro. OMSF@JK incorporated PF-127 injectable hydrogel (PF-OMSF@JK) has a soft consistency similar to that of the human spinal cord and thus, shows a high cytocompatibility with DPSCs. The cross-sectional micromorphology of the hydrogel shows a continuous porous structure. Last, the PF-OMSF@JK composite hydrogel considerably improves the in vivo SCI regeneration in Sprague-Dawley rats through a reduction in inflammation and neuronal differentiation of the incorporated stem cells as confirmed using western blotting and immunohistochemistry. The highly encouraging in vivo results prove that this novel design on hydrogel is a promising therapy for SCI regeneration with the potential for clinical translation.

On the Use of the Fricke-Pluronic F-127 Gel Dosimeter for Radiation Isocenter Testing of a Medical Linear Accelerator

This work presents a Fricke-XO-Pluronic F-127 2D radiochromic dosimeter with a flat-bed scanner for 2D reading and a dedicated data processing software package as a tool for performing coincidence testing of the radiation and mechanical isocenter of a medical accelerator. The optimal irradiation parameters were determined as follows: monitor units per beam and multi-leaf collimator gap, which are ≤750-≤2500 MU and 2-5 mm, respectively, for a cuboidal container with dimensions of 12 × 12 × 0.3 cm3. Despite the diffusion of Fe3+ ions occurring during irradiation, 2D reading can be performed at least 3 h after irradiation, without affecting the calculation performance of the coincidence test. The test was successfully performed for various irradiation settings. Overall, the Fricke-XO-Pluronic F-127 dosimeter has proven to be a potential tool for the coincidence testing of medical accelerators.

Digital Light Processing 4D Printing of Poloxamer Micelles for Facile Fabrication of Multifunctional Biocompatible Hydrogels as Tailored Wearable Sensors

The lack of both digital light processing (DLP) compatible and biocompatible photopolymers, along with inappropriate material properties required for wearable sensor applications, substantially hinders the employment of DLP 3D printing in the fabrication of multifunctional hydrogels. Herein, we discovered and implemented a photoreactive poloxamer derivative, Pluronic F-127 diacrylate, which overcomes these limitations and is optimized to achieve DLP 3D printed micelle-based hydrogels with high structural complexity, resolution, and precision. In addition, the dehydrated hydrogels exhibit a shape-memory effect and are conformally attached to the geometry of the detection point after rehydration, which implies the 4D printing characteristic of the fabrication process and is beneficial for the storage and application of the device. The excellent cytocompatibility and in vivo biocompatibility further strengthen the potential application of the poloxamer micelle-based hydrogels as a platform for multifunctional wearable systems. After processing them with a lithium chloride (LiCl) solution, multifunctional conductive ionic hydrogels with antifreezing and antiswelling properties along with good transparency and water retention are easily prepared. As capacitive flexible sensors, the DLP 3D printed micelle-based hydrogel devices exhibit excellent sensitivity, cycling stability, and durability in detecting multimodal deformations. Moreover, the DLP 3D printed conductive hydrogels are successfully applied as real-time human motion and tactile sensors with satisfactory sensing performances even in a -20 °C low-temperature environment.

A Novel Tendon Injury Model, Induced by Collagenase Administration Combined with a Thermo-Responsive Hydrogel in Rats, Reproduces the Pathogenesis of Human Degenerative Tendinopathy

Patellar tendinopathy is a common clinical problem, but its underlying pathophysiology remains poorly understood, primarily due to the absence of a representative experimental model. The most widely used method to generate such a model is collagenase injection, although this method possesses limitations. We developed an optimized rat model of patellar tendinopathy via the ultrasound-guided injection of collagenase mixed with a thermo-responsive Pluronic hydrogel into the patellar tendon of sixty male Wistar rats. All analyses were carried out at 3, 7, 14, 30, and 60 days post-injury. We confirmed that our rat model reproduced the pathophysiology observed in human patients through analyses of ultrasonography, histology, immunofluorescence, and biomechanical parameters. Tendons that were injured by the injection of the collagenase-Pluronic mixture exhibited a significant increase in the cross-sectional area (p < 0.01), a high degree of tissue disorganization and hypercellularity, significantly strong neovascularization (p < 0.01), important changes in the levels of types I and III collagen expression, and the organization and presence of intra-tendinous calcifications. Decreases in the maximum rupture force and stiffness were also observed. These results demonstrate that our model replicates the key features observed in human patellar tendinopathy. Collagenase is evenly distributed, as the Pluronic hydrogel prevents its leakage and thus, damage to surrounding tissues. Therefore, this model is valuable for testing new treatments for patellar tendinopathy.

Development of hybrid 3D printing approach for fabrication of high-strength hydroxyapatite bioscaffold using FDM and DLP techniques

This study develops a hybrid 3D printing approach that combines fused deposition modeling (FDM) and digital light processing (DLP) techniques for fabricating bioscaffolds, enabling rapid mass production. The FDM technique fabricates outer molds, while DLP prints struts for creating penetrating channels. By combining these components, hydroxyapatite (HA) bioscaffolds with different channel sizes (600, 800, and 1000μm) and designed porosities (10%, 12.5%, and 15%) are fabricated using the slurry casting method with centrifugal vacuum defoaming for significant densification. This innovative method produces high-strength bioscaffolds with an overall porosity of 32%-37%, featuring tightly bound HA grains and a layered surface structure, resulting in remarkable cell viability and adhesion, along with minimal degradation rates and superior calcium phosphate deposition. The HA scaffolds show hardness ranging from 1.43 to 1.87 GPa, with increasing compressive strength as the designed porosity and channel size decrease. Compared to human cancellous bone at a similar porosity range of 30%-40%, exhibiting compressive strengths of 13-70 MPa and moduli of 0.8-8 GPa, the HA scaffolds demonstrate robust strengths ranging from 40 to 73 MPa, paired with lower moduli of 0.7-1.23 GPa. These attributes make them well-suited for cancellous bone repair, effectively mitigating issues like stress shielding and bone atrophy.

Recent Advances in Nanocarrier-based Approaches to Atopic Dermatitis and Emerging Trends in Drug Development and Design

Atopic dermatitis (AD), commonly known as Eczema, is a non-communicable skin condition that tends to become chronic. The deteriorating immunological abnormalities are marked by mild to severe erythema, severe itching, and recurrent eczematous lesions. Different pharmacological approaches are used to treat AD. The problem with commercial topical preparations lies in the limitation of skin atrophy, systemic side effects, and burning sensation that decreases patient compliance. The carrier-based system promises to eliminate these shortcomings; thus, a novel approach to treating AD is required. Liposomes, microemulsions, solid lipid nanoparticles (SLNs), nanoemulsions, etc., have been developed recently to address this ailment. Despite extensive research in the development method and various techniques, it has been challenging to demonstrate the commercial feasibility of these carrier- based systems, which illustrates a gap among the different research areas. Further, different soft wares and other tools have proliferated among biochemists as part of a cooperative approach to drug discovery. It is crucial in designing, developing, and analyzing processes in the pharmaceutical industry and is widely used to reduce costs, accelerate the development of biologically innovative active ingredients, and shorten the development time. This review sheds light on the compilation of extensive efforts to combat this disease, the product development processes, commercial products along with patents in this regard, numerous options for each step of computer-aided drug design, including in silico pharmacokinetics, pharmacodynamics, and toxicity screening or predictions that are important in finding the drug-like compounds.

Injectable Thermoresponsive Microparticle/Hydrogel System with Superparamagnetic Nanoparticles for Drug Release and Magnetic Hyperthermia Applications

Cancer is a disease that continues to greatly impact our society. Developing new and more personalized treatment options is crucial to decreasing the cancer burden. In this study, we combined magnetic polysaccharide microparticles with a Pluronic thermoresponsive hydrogel to develop a multifunctional, injectable drug delivery system (DDS) for magnetic hyperthermia applications. Gellan gum and alginate microparticles were loaded with superparamagnetic iron oxide nanoparticles (SPIONs) with and without coating. The magnetic microparticles' registered temperature increases up to 4 °C upon the application of an alternating magnetic field. These magnetic microparticles were mixed with drug-loaded microparticles, and, subsequently, this mixture was embedded within a Pluronic thermoresponsive hydrogel that is capable of being in the gel state at 37 °C. The proposed DDS was capable of slowly releasing methylene blue, used as a model drug, for up to 9 days. The developed hydrogel/microparticle system had a smaller rate of drug release compared with microparticles alone. This system proved to be a potential thermoresponsive DDS suitable for magnetic hyperthermia applications, thus enabling a synergistic treatment for cancer.

Extracellular vesicle biopotentiated hydrogels for diabetic wound healing: The art of living nanomaterials combined with soft scaffolds

Diabetic wounds (DWs) pose a major challenge for the public health system owing to their high incidence, complex pathogenesis, and long recovery time; thus, there is an urgent need to develop innovative therapies to accelerate the healing process of diabetic wounds. As natural nanovesicles, extracellular vesicles (EVs) are rich in sources with low immunogenicity and abundant nutritive molecules and exert potent therapeutic effects on diabetic wound healing. To avoid the rapid removal of EVs, a suitable delivery system is required for their controlled release. Owing to the advantages of high porosity, good biocompatibility, and adjustable physical and chemical properties of hydrogels, EV biopotentiated hydrogels can aid in achieving precise and favorable therapy against diabetic wounds. This review highlights the different design strategies, therapeutic effects, and mechanisms of EV biopotentiated hydrogels. We also discussed the future challenges and opportunities of using EV biopotentiated hydrogels for diabetic wound healing.

Development of a thermosensitive hydrogel based on Polaxamer 407 and gellan gum with inclusion complexes (Sulfobutylated-β-cyclodextrin-Farnesol) as a local drug delivery system

This work proposes the development of a thermosensitive local drug release system based on Polaxamer 407, also known as Pluronic® F-127 (PF-127), Gellan Gum (GG) and the inclusion complex Sulfobutylated-β-cyclodextrin (CD) with Farnesol (FOH). Rheological properties of the hydrogels and their degradation were studied. According to the rheological results, a solution of 20% w/v of PF-127 forms a strong gel with a gelling temperature of about 25 °C (storage modulus of 15,000 Pa). The addition of the GG increased the storage modulus (optimal concentration of 0.5 % w/v) twofold without modifying the gelling temperature. Moreover, including 0.5% w/v of GG also increased 6 times the degradation time of the hydrogel. Regarding the inclusion complex, the addition of free CD decreased the viscosity and the gel strength since polymer chains were included in CD cavity without affecting the gelling temperature. Contrarily, the inclusion complex CD-FOH did not significantly modify any property of the formulation because the FOH was hosted in the CD. Furthermore, a mathematical model was developed to adjust the degradation time. This model highlights that the addition of the GG decreases the number of released chains from the polymeric network (which coincides with an increase in the storage modulus) and that the free CD reduces the degradation rate, protecting the polymeric chains. Finally, FOH release was quantified with a specific device, that was designed and printed for this type of system, observing a sustainable drug release (similar to FOH aqueous solubility, 8 μM) dependent on polymer degradation.

Photodynamic Therapy Directed to Melanoma Skin Cancer by Thermosensitive Hydrogel Containing Chlorophyll A

Melanoma, a severe form of skin cancer intricately linked to genetic and environmental factors, is predicted to reach 100,000 new cases worldwide by 2040, underscoring the need for effective and safe treatment options. In this study, we assessed the efficacy of a photosensitizer called Chlorophyll A (Chl-A) incorporated into hydrogels (HGs) made of chitosan (CS) and poloxamer 407 (P407) for Photodynamic Therapy (PDT) against the murine melanoma cell line B16-F10. The HG was evaluated through various tests, including rheological studies, SEM, and ATR-FTIR, along with cell viability assays. The CS- and P407-based HGs effectively released Chl-A and possessed the necessary properties for topical application. The photodynamic activity of the HG containing Chl-A was evaluated in vitro, demonstrating high therapeutic potential, with an IC50 of 25.99 µM-an appealing result when compared to studies in the literature reporting an IC50 of 173.8 µM for cisplatin, used as a positive control drug. The developed formulation of CS and P407-based HG, serving as a thermosensitive system for topical applications, successfully controlled the release of Chl-A. In vitro cell studies associated with PDT exhibited potential against the melanoma cell line.

Development and characterization of a poloxamer hydrogel composed of human mesenchymal stromal cells (hMSCs) for reepithelization of skin injuries

Wound healing is a natural physiological reaction to tissue injury. Hydrogels show attractive advantages in wound healing not only due to their biodegradability, biocompatibility and permeability but also because provide an excellent environment for cell migration and proliferation. The main objective of the present study was the design and characterization of a hydrogel loaded with human mesenchymal stromal cells (hMSCs) for use in would healing of superficial skin injures. Poloxamer 407® was used as biocompatible biomaterial to embed hMSCs. The developed hydrogel containing 20 % (w/w) of polymer resulted in the best formulation with respect to physical, mechanical, morphological and biological properties. Its high swelling capacity confirmed the hydrogel's capacity to absorb wounds' exudate. LIVE/DEAD® assay confirm that hMSCs remained viable for at least 48 h when loaded into the hydrogels. Adding increasing concentrations of hMSCs-loaded hydrogel to the epithelium did not affect keratinocytes' viability and healing capacity and all wound area was closed in less than one day. Our study opens opportunities to exploit poloxamer hydrogels as cell carriers for the treatment of skin superficial wound.

Antimicrobial polymer-loaded hydrogels for the topical treatment of multidrug-resistant wound biofilm infections

Integration of antimicrobial polymeric nanoparticles into hydrogel materials presents a promising strategy to address multidrug-resistant biofilm infections. Here we report an injectable hydrogel loaded with engineered cationic antimicrobial polymeric nanoparticles (PNPs) for the effective topical treatment of severe wound biofilm infections. The PNPs demonstrated biofilm penetration and disruption, resulting in the eradication of resistant and persister cells that reside within the biofilm. Significantly, PNPs did not elicit resistance development even after multiple exposures to sub-therapeutic doses. In vitro studies showed PNPs significantly reduced prolonged inflammation due to infection and promoted fibroblast migration. These PNPs were then incorporated into Poloxamer 407 (P407) hydrogels and utilized as an inert carrier for PNPs to provide a controlled and sustained topical release of the antimicrobial nanoparticles at the wound area. In vivo studies using a mature (4-day) wound biofilm infection in a murine model mimicking severe human wound infections demonstrated provided 99% bacterial biofilm clearance and significantly enhanced wound healing. Overall, this work demonstrated the efficacy and selectivity of the antimicrobial polymer-loaded hydrogel platform as a topical treatment for difficult-to-treat wound biofilm infections.

Simple, Rapid, and Large-Scale Fabrication of Multi-Branched Hydrogels Based on Viscous Fingering for Cell Culture Applications

Hydrogels are widely used in cell culture applications. For fabricating tissues and organs, it is essential to produce hydrogels with specific structures. For instance, multiple-branched hydrogels are desirable for the development of network architectures that resemble the biological vascular network. However, existing techniques are inefficient and time-consuming for this application. To address this issue, a simple, rapid, and large-scale fabrication method based on viscous fingering is proposed. This approach utilizes only two plates. To produce a thin solution, a high-viscosity solution is introduced into the space between the plates, and one of the plates is peeled off. During this procedure, the solution's high viscosity results in the formation of multi-branched structures. Using this strategy, 180 mm × 200 mm multi-branched Pluronic F-127 hydrogels are successfully fabricated within 1 min. These structures are used as sacrificial layers for the fabrication of polydimethylsiloxane channels for culturing human umbilical vein endothelial cells (HUVECs). Similarly, multi-branched Matrigel and calcium (Ca)-alginate hydrogel structures are fabricated, and HUVECs are successfully cultured inside the hydrogels. Also, the hydrogels are collected from the plate, while maintaining their structures. The proposed fabrication technique will contribute to the development of network architectures such as vascular structures in tissue engineering.

A dual functional polypeptide with antibacterial and anti-inflammatory properties for the treatment of periodontitis

Periodontitis has been reported as the sixth most prevalent disease in human beings. This destructive disease is closely related to systemic diseases. Existing local drug delivery systems for periodontitis suffer from poor antibacterial effect and drug resistance. Inspired by the pathogenesis of periodontitis, we implemented a strategy to construct a dual functional polypeptide LL37-C15, which exhibited remarkable antibacterial effect against P. gingivalis and A. actinomycetemcomitans. In addition, LL37-C15 inhibits the release of pro-inflammatory cytokines by controlling the inflammatory pathway and reversing macrophage M1. Furthermore, the anti-inflammatory effect of LL37-C15 was also verified in vivo in a periodontitis rat model through the morphometry and histological observations of alveolar bone, hematoxylin-eosin, and Trap staining in gingival tissue. The results of molecular dynamics simulations showed that LL37-C15 could selectively destroy the bacterial cell membrane and protect the animal cell membrane in a self-destructive manner. The results showed that the polypeptide LL37-C15, as a novel promising therapeutic agent, exhibited a great potential for the periodontitis management. What's more, this dual functional polypeptide provides a promising strategy for building a multifunctional therapeutic platform against the inflammation and other diseases.

A colloidal hydrogel-based drug delivery system overcomes the limitation of combining bisphosphonates with bioactive glasses: in vitro evidence of a potential selective bone cancer treatment allied with bone regeneration

Bisphosphonates are a class of drugs that induce bone cancer cell death and favor bone regeneration, making them suitable for bone cancer treatment. However, when combined with bioactive glasses to enhance bone regeneration, a chemical bond between biphosphonates and the glass surface inactivates their mechanism of action. A new colloidal hydrogel-based drug delivery system could overcome that limitation once bisphosphonates, such as zoledronic acid (ZA), are incorporated into hydrogel micelles, avoiding their interaction with the glass surface. In this work, we proposed formulations based on a poloxamer 407 thermo-responsive hydrogel matrix containing holmium-doped bioactive glass nanoparticles and different concentrations (0.05 and 5 mg/mL) of ZA. We characterized the influence of the glass and the ZA on the hydrogel properties. In addition, a drug concentration screening was performed, and biological characterizations evaluated the best result. The biological characterization consisted of evaluating cytotoxicity and in vitro bone regeneration ability through cell migration and quantification of genes related to osteogeneses through RT-PCR. The results suggest that the addition of glasses and ZA to the poloxamer did not significantly influence the sol-gel transition of the hydrogels (around 13 °C) regardless of the ZA content. However, the ZA at high concentration (PL-ZA100) decreased the enthalpy of gel formation from 68 to 43 kJ.mol^-1 when compared with the pure hydrogel formulation (PL), suggesting a water structurer role of ZA, which is withdrawn when glass particles are added to the system (PL-BG5Ho-ZA100). Solid-state 31P nuclear resonance spectroscopy results showed that part of the ZA is chemically bonded to the glass surface, which explains the withdrawal in the water structurer role of ZA when the glasses were incorporated into the hydrogel. Besides, based on the drug release results, we proposed a model where part of the ZA is "free," encapsulated in the hydrogel matrix, while another part of the ZA is bonded to the glass surface. Finally, considering the in vitro results and our proposed model, the ratio between "free" and "bonded" ZA in our drug delivery systems showed in vitro evidence of a cancer treatment that selectively kills osteosarcoma cells while still favoring an osteogenic microenvironment. By overcoming the limitation of combining bisphosphonates with bioactive glasses, hydrogel-based drug delivery systems can be a solution for the development of new formulations proposed for bone cancer treatment in conjunction with bone regeneration.

Design of Functional Pluronic-Based Precursors for Tailoring Hydrogel Thermoresponsiveness and Cell-Adhesive Properties

In this study, functional Pluronic F127 precursors were designed and synthesized for the preparation of thermosensitive hydrogels. Using linear Pluronic thioacetate and Pluronic multi-acrylate precursors, F127-based hydrogels were prepared through thioacetate deprotection-mediated Michael-type addition. The properties of these gels were compared to those obtained through free radical crosslinking of F127 diacrylate. Temperature was found to have a clear influence on gel swelling as a result of F127 thermoresponsiveness. The macromolecular architecture and functionality of the precursors were also optimized and characterized in terms of gelation kinetics and drug diffusion. In vitro tests were conducted on fibroblasts and endothelial cells to assess their response to cellular adhesion with Pluronic gels that were functionalized with an RGD peptide or pretreated with serum proteins to promote cell adhesion. This study provides a method for creating tailored hydrogels suitable for various biomedical applications, such as soft-tissue engineering, cell encapsulation, wound healing, and sustained delivery of therapeutic molecules.

PF127 Hydrogel-Based Delivery of Exosomal CTNNB1 from Mesenchymal Stem Cells Induces Osteogenic Differentiation during the Repair of Alveolar Bone Defects

Pluronic F127 (PF127) hydrogel has been highlighted as a promising biomaterial for bone regeneration, but the specific molecular mechanism remains largely unknown. Herein, we addressed this issue in a temperature-responsive PF127 hydrogel loaded with bone marrow mesenchymal stem cells (BMSCs)-derived exosomes (Exos) (PF127 hydrogel@BMSC-Exos) during alveolar bone regeneration. Genes enriched in BMSC-Exos and upregulated during the osteogenic differentiation of BMSCs and their downstream regulators were predicted by bioinformatics analyses. CTNNB1 was predicted to be the key gene of BMSC-Exos in the osteogenic differentiation of BMSCs, during which miR-146a-5p, IRAK1, and TRAF6 might be the downstream factors. Osteogenic differentiation was induced in BMSCs, in which ectopic expression of CTNNB1 was introduced and from which Exos were isolated. The CTNNB1-enriched PF127 hydrogel@BMSC-Exos were constructed and implanted into in vivo rat models of alveolar bone defects. In vitro experiment data showed that PF127 hydrogel@BMSC-Exos efficiently delivered CTNNB1 to BMSCs, which subsequently promoted the osteogenic differentiation of BMSCs, as evidenced by enhanced ALP staining intensity and activity, extracellular matrix mineralization (p < 0.05), and upregulated RUNX2 and OCN expression (p < 0.05). Functional experiments were conducted to examine the relationships among CTNNB1, microRNA (miR)-146a-5p, and IRAK1 and TRAF6. Mechanistically, CTNNB1 activated miR-146a-5p transcription to downregulate IRAK1 and TRAF6 (p < 0.05), which induced the osteogenic differentiation of BMSCs and facilitated alveolar bone regeneration in rats (increased new bone formation and elevated BV/TV ratio and BMD, all with p < 0.05). Collectively, CTNNB1-containing PF127 hydrogel@BMSC-Exos promote the osteogenic differentiation of BMSCs by regulating the miR-146a-5p/IRAK1/TRAF6 axis, thus inducing the repair of alveolar bone defects in rats.

Pluronic® F127 Hydrogel Containing Silver Nanoparticles in Skin Burn Regeneration: An Experimental Approach from Fundamental to Translational Research

Presently, skin burns are considered one of the main public health problems and lack therapeutic options. In recent years, silver nanoparticles (AgNPs) have been widely studied, playing an increasingly important role in wound healing due to their antibacterial activity. This work is focused on the production and characterization of AgNPs loaded in a Pluronic® F127 hydrogel, as well as assessing its antimicrobial and wound-healing potential. Pluronic® F127 has been extensively explored for therapeutic applications mainly due to its appealing properties. The developed AgNPs had an average size of 48.04 ± 14.87 nm (when prepared by method C) and a negative surface charge. Macroscopically, the AgNPs solution presented a translucent yellow coloration with a characteristic absorption peak at 407 nm. Microscopically, the AgNPs presented a multiform morphology with small sizes (~50 nm). Skin permeation studies revealed that no AgNPs permeated the skin after 24 h. AgNPs further demonstrated antimicrobial activity against different bacterial species predominant in burns. A chemical burn model was developed to perform preliminary in vivo assays and the results showed that the performance of the developed AgNPs loaded in hydrogel, with smaller silver dose, was comparable with a commercial silver cream using higher doses. In conclusion, hydrogel-loaded AgNPs is potentially an important resource in the treatment of skin burns due to their proven efficacy by topical administration.

3D Printing as a Technological Strategy for the Personalized Treatment of Wound Healing

Wound healing is a dynamic process which involves stages of hemostasis, inflammation, proliferation and remodeling. Any error in this process results in abnormal wound healing, generating financial burdens for health systems and even affecting the physical and mental health of the patient. Traditional dressings do not meet the complexities of ideal treatment in all types of wounds. For this reason, in the last decades, different materials for drug delivery and for the treatment of wounds have been proposed reaching novel level of standards, such as 3D printing techniques. The use of natural or synthetic polymers, and the correct design of these printed products loaded with cells and/or combined with active compounds, can generate an effective system for the treatment of wounds, improving the healing process and generating customized dressings according to the patient needs. This manuscript provides a comprehensive review of different types of 3D printing techniques, as well as its use in wound healing and its different stages, including the advantages and limitations of additive manufacturing and future perspectives.

Temperature Induced Gelation and Antimicrobial Properties of Pluronic F127 Based Systems

Different formulations containing Pluronic F127 and polysaccharides (chitosan, sodium alginate, gellan gum, and κ-carrageenan) were investigated as potential injectable gels that behave as free-flowing liquid with reduced viscosity at low temperatures and displayed solid-like properties at 37 °C. In addition, ZnO nanoparticles, lysozyme, or curcumin were added for testing the antimicrobial properties of the thermal-sensitive gels. Rheological investigations evidenced small changes in transition temperature and kinetics of gelation at 37 °C in presence of polysaccharides. However, the gel formation is very delayed in the presence of curcumin. The antimicrobial properties of Pluronic F127 gels are very modest even by adding chitosan, lysozyme, or ZnO nanoparticles. A remarkable enhancement of antimicrobial activity was observed in the presence of curcumin. Chitosan addition to Pluronic/curcumin systems improves their viscoelasticity, antimicrobial activity, and stability in time. The balance between viscoelastic and antimicrobial characteristics needs to be considered in the formulation of Pluronic F127 gels suitable for biomedical and pharmaceutical applications.

User-designed device with programmable release profile for localized treatment

Three-dimensional printing enables precise and on-demand manufacture of customizable drug delivery systems to advance healthcare toward the goal of personalized medicine. However, major challenges remain in realizing personalized drug delivery that fits a patient-specific drug dosing schedule using local drug delivery systems. In this study, a user-designed device is developed as implantable therapeutics that can realize personalized drug release kinetics by programming the inner structural design on the microscale. The drug release kinetics required for various treatments, including dose-dense therapy and combination therapy, can be implemented by controlling the dosage and combination of drugs along with the rate, duration, initiation time, and time interval of drug release according to the device layer design. After implantation of the capsular device in mice, the in vitro-in vivo and pharmacokinetic evaluation of the device is performed, and the therapeutic effect of the developed device is achieved through the local release of doxorubicin. The developed user-designed device provides a novel platform for developing next-generation drug delivery systems for personalized and localized therapy.

Synthetic materials in craniofacial regenerative medicine: A comprehensive overview

The state-of-the-art approach to regenerating different tissues and organs is tissue engineering which includes the three parts of stem cells (SCs), scaffolds, and growth factors. Cellular behaviors such as propagation, differentiation, and assembling the extracellular matrix (ECM) are influenced by the cell's microenvironment. Imitating the cell's natural environment, such as scaffolds, is vital to create appropriate tissue. Craniofacial tissue engineering refers to regenerating tissues found in the brain and the face parts such as bone, muscle, and artery. More biocompatible and biodegradable scaffolds are more commensurate with tissue remodeling and more appropriate for cell culture, signaling, and adhesion. Synthetic materials play significant roles and have become more prevalent in medical applications. They have also been used in different forms for producing a microenvironment as ECM for cells. Synthetic scaffolds may be comprised of polymers, bioceramics, or hybrids of natural/synthetic materials. Synthetic scaffolds have produced ECM-like materials that can properly mimic and regulate the tissue microenvironment's physical, mechanical, chemical, and biological properties, manage adherence of biomolecules and adjust the material's degradability. The present review article is focused on synthetic materials used in craniofacial tissue engineering in recent decades.

Novel Osteogenic and Easily Handled Endodontic Calcium Silicate Cement Using Pluronic F127 Hydrogel

Calcium silicate cement (CSC) is widely used as an endodontic material in clinical applications such as direct pulp capping, pulpotomy, or root canal. CSC has good biocompatibility, sealing properties, and the ability to enhance hard tissue regeneration. However, the disadvantage of CSC is the difficulty in handling when placing it into endodontic tissue due to the long setting time. Several attempts have been made to improve handling of CSC; however, these methods were limited by osteogenic properties. To overcome such a disadvantage, this study investigated the use of Pluronic F127 (F127) for the development easy-to-handle novel endodontic CSCs with osteogenic properties. In this case, different concentrations of F127 (5%, 10%, 20%, 30%, and 40%) were implemented to generate CSC specimens H5, H10, H20, H30, and H40, respectively. Calcium ion was continuously released for 28 days. In addition, each group resulted in apatite formation for 28 days corresponding to calcium ion release. The concentration of F127 showed opposite relationships with water solubility and compressive strength. The H20 group showed a high level of osteogenic activity compared to other groups at 14 days. Mineralization of the H20 group was higher than that of the other groups. This study indicates that the novel F127-based hydrogel with CSC can potentially be used as endodontic filler.

Cross-Linked Lyotropic Liquid Crystal Particles Functionalized with Antimicrobial Peptides

Antimicrobial peptides (AMPs) are promising alternatives to traditional antibiotics for addressing bacterial infections - including life-threatening antibiotic resistant infections. AMPs have a broad spectrum of antimicrobial activity and show a low probability to induce resistance. However, the poor serum stability of AMPs has limited their usage in clinical treatment. To enable improved serum stability while maintaining high antibacterial effect of AMPs, this study describes a material wherein AMPs are covalently bonded to micro-sized particles of cross-linked lyotropic liquid crystals, formed by the self-assembly of the block copolymer Pluronic F-127. The liquid crystal particles were shown to have antibacterial effect corresponding to a 4 log reduction against Staphylococcus aureus. The particles were structurally and chemically analyzed by small angle X-ray scattering, Fourier transform infra-red spectroscopy and Raman spectroscopy, confirming that the liquid crystal structure was maintained within the particles with the AMPs covalently bonded. The bonding to the particles gave the AMPs improved stability in serum, as they retained almost all of the antibacterial potency for 2 days compared to free AMPs, which lost all of its antibacterial potency within a day. Furthermore, insight regarding mode of action was obtained by cryogenic transmission electron microscopy, which showed the antimicrobial particles interacting with the surface of bacteria.

Recent advances in nanoformulation development of Ritonavir, a key protease inhibitor used in the treatment of HIV-AIDS

INTRODUCTION

AIDS is one of the world's most serious public health challenges. Protease inhibitors are key components of AIDS treatment regimen. Ritonavir is a well-known protease inhibitor with low aqueous solubility belonging to BCS class II category. Some of the severe adverse effects associated with this drug restricted its use in the treatment of AIDS. However, several attempts were made by researchers in the past to enhance the oral bioavailability of Ritonavir.

AREAS COVERED

The current review mainly focuses on the adverse effects of Ritonavir and recent approaches followed by researchers on the development of nanoformulations of Ritonavir. Further, various patents filed on Ritonavir have also been discussed in the current review.

EXPERT OPINION

Most research on nanoformulation development for Ritonavir is mainly focused on enhancing the solubility and oral bioavailability of the drug. Some of the researchers focused on the lymphatic targeting of the drug in order to bypass the hepatic metabolism of the drug. However, most of the research topics did not cover the toxicity evaluation of the developed formulation. Since the major issue of Ritonavir is not only oral bioavailability but also drug-induced toxicity, this area needs to be considered during the formulation development.

Human adipose-derived mesenchymal stem cells-derived exosomes encapsulated in pluronic F127 hydrogel promote wound healing and regeneration

Background

Large area skin trauma has always been a great challenge for both patients and clinicians. Exosomes originating from human adipose-derived mesenchymal stem cells (hADSCs) have been a novel promising cell-free treatment in cutaneous damage repair. Nevertheless, the low retention rate of exosomes post-transplantation in vivo remains a significant challenge in clinical applications. Herein, we purposed to explore the potential clinical application roles of hADSCs-Exos encapsulated in functional PF-127 hydrogel in wound healing.

Methods

hADSCs-Exos were isolated from human hADSCs by ultracentrifugation. An injectable, biocompatible, and thermo-sensitive hydrogel Pluronic F-127 hydrogel was employed to encapsulate allogeneic hADSCs-Exos, and this complex was topically applied to a full-thickness cutaneous wound in mice. On different days post-transplantation, the mice were sacrificed, and the skin tissue was excised for histological and immunohistochemical analysis.

Results

Compared with hADSCs-Exos or PF-127 only, PF-127/hADSCs-Exos complexes enhanced skin wound healing, promoted re-epithelialization, increased expression of Ki67, α-SMA, and CD31, facilitated collagen synthesis (Collagen I, Collagen III), up-regulated expression of skin barrier proteins (KRT1, AQP3), and reduced inflammation (IL-6, TNF-α, CD68, CD206). By using PF-127/hADSCs-Exos complexes, hADSCs-Exos can be administrated at lower doses frequency while maintaining the same therapeutic effects.

Conclusion

Administration of hADSCs-Exos in PF-127 improves the efficiency of exosome delivery, maintains the bioactivity of hADSCs-Exos, and optimizes the performance of hADSCs-Exos. Thus, this biomaterial-based exosome will be a promising treatment approach for the cutaneous rejuvenation of skin wounds.

Impact of Salt on Thermal Stability and Dose Response of the Fricke-XO-Pluronic F-127 3D Radiotherapy Dosimeter

Fricke-XO-Pluronic F-127 has recently been proposed as a 3D dosimeter for radiotherapy. It contains the typical ingredients of the Fricke ionizing radiation dosimeter, which are embedded in a physical gel of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (Pluronic F-127). The main reactions upon irradiation are the conversion of Fe⁺² to Fe⁺³ and the formation of a colored complex with XO ([XO-Fe]⁺³). The study attempts to optimize the dosimeter in terms of its solution-to-gel transition temperature. In order to lower this temperature, the use of NaCl salt has been proposed. The new composition was characterized in order to obtain information on its thermal performance, storage stability, dose response to irradiation with a medical accelerator emitting different types of radiation, and tissue equivalence. The results obtained show an improvement in the sol-gel transition temperature and dose sensitivity compared to the composition without NaCl and broaden the knowledge of the Fricke-XO-Pluronic F-127.

Silymarin nanocrystals-laden chondroitin sulphate-based thermoreversible hydrogels; A promising approach for bioavailability enhancement

Hydrogels has gained tremendous interest as a controlled release drug delivery. However, currently it is a big challenge to attain high drug-loading as well as stable and sustained release of hydrophobic drugs. The poor aqueous solubility and low bioavailability of many drugs have driven the need for research in new formulations. This manuscript hypothesized that incorporation of nanocrystals of hydrophobic drug, such as silymarin into thermoreversible hydrogel could be a solution to these problems. Herein, we prepared nanocrystals of silymarin by antisolvent precipitation technique and characterized for morphology, particle size, polydispersity index (PDI) and zeta potential. Moreover, physical cross-linking of hydrogel formulations based on chondroitin sulphate (CS), kappa-Carrageenan (κ-Cr) and Pluronic® F127 was confirmed by Fourier transformed infrared spectroscopy (FT-IR). The hydrogel gelation time and temperature of optimized hydrogel was 14 ± 3.2 s and 34 ± 0.6 °C, respectively. The release data revealed controlled release of silymarin up to 48 h and in-vivo pharmacokinetic profiling was done in rabbits and further analyzed by high-performance liquid chromatography (HPLC). It is believed that the nanocrystals loaded thermoreversible injectable hydrogel system fabricated in this study provides high drug loading as well as controlled and stable release of hydrophobic drug for extended period.

Human Umbilical Cord Mesenchymal Stem Cells Encapsulated with Pluronic F-127 Enhance the Regeneration and Angiogenesis of Thin Endometrium in Rat via Local IL-1β Stimulation

Thin endometrium (< 7 mm) could cause low clinical pregnancy, reduced live birth, increased spontaneous abortion, and decreased birth weight. However, the treatments for thin endometrium have not been well developed. In this study, we aim to determine the role of Pluronic F-127 (PF-127) encapsulation of human umbilical cord mesenchymal stem cells (hUC-MSCs) in the regeneration of thin endometrium and its underlying mechanism. Thin endometrium rat model was created by infusion of 95% ethanol. Thin endometrium modeled rat uterus were treated with saline, hUC-MSCs, PF-127, or hUC-MSCs plus PF-127 separately. Regenerated rat uterus was measured for gene expression levels of angiogenesis factors and histological morphology. Angiogenesis capacity of interleukin-1 beta (IL-1β)-primed hUC-MSCs was monitored via quantitative polymerase chain reaction (q-PCR), Luminex assay, and tube formation assay. Decreased endometrium thickness and gland number and increased inflammatory factor IL-1β were achieved in the thin endometrium rat model. Embedding of hUC-MSCs with PF-127 could prolong the hUC-MSCs retaining, which could further enhance endometrium thickness and gland number in the thin endometrium rat model via increasing angiogenesis capacity. Conditional medium derived from IL-1β-primed hUC-MSCs increased the concentration of angiogenesis factors (basic fibroblast growth factor (bFGF), vascular endothelial growth factors (VEGF), and hepatocyte growth factor (HGF)). Improvement in the thickness, number of glands, and newly generated blood vessels could be achieved by uterus endometrium treatment with PF-127 and hUC-MSCs transplantation. Local IL-1β stimulation-primed hUC-MSCs promoted the release of angiogenesis factors and may play a vital role on thin endometrium regeneration.

Bioink Formulation and Machine Learning-Empowered Bioprinting Optimization

Bioprinting enables the fabrication of complex, heterogeneous tissues through robotically-controlled placement of cells and biomaterials. It has been rapidly developing into a powerful and versatile tool for tissue engineering. Recent advances in bioprinting modalities and biofabrication strategies as well as new materials and chemistries have led to improved mimicry and development of physiologically relevant tissue architectures constituted with multiple cell types and heterogeneous spatial material properties. Machine learning (ML) has been applied to accelerate these processes. It is a new paradigm for bioprinting. In this review, we explore current trends in bioink formulation and how ML has been used to accelerate optimization and enable real-time error detection as well as to reduce the iterative steps necessary for bioink formulation. We examined how rheometric properties, including shear storage, loss moduli, viscosity, shear-thinning property of biomaterials affect the printability of a bioink. Furthermore, we scrutinized the interplays between yield shear stress and the printability of a bioink. Moreover, we systematically surveyed the application of ML in precision in situ surgical site bioprinting, closed-loop AI printing, and post-printing optimization.

Dual Action Nitric Oxide and Fluoride Ion-Releasing Hydrogels for Combating Dental Caries

Demineralization and breakdown of tooth enamel are characterized by a condition called dental caries or tooth decay, which is caused by two main factors: (1) highly acidic food intake without proper oral hygiene and (2) overactive oral bacteria generating acidic metabolic byproducts. Fluoride treatments have been shown to help rebuild the hydroxyapatite structures that make up 98% of enamel but do not tackle the bacterial overload that continues to threaten future demineralization. Herein, we have created a dual-function Pluronic F127-alginate hydrogel with nitric oxide (NO)- and fluoride-releasing capabilities for the two-pronged treatment of dental caries. Analysis of the hydrogels demonstrated porous, shear-thinning behaviors with tunable mechanical properties. Varying the weight percent of the NO donor S-nitrosoglutathione (GSNO) within the hydrogel enabled physiologically actionable NO release over 4 h, with the fabricated gels demonstrating storage stability over 21 days. This NO-releasing capability resulted in a 97.59% reduction of viable Streptococcus mutans in the planktonic state over 4 h and reduced the preformed biofilm mass by 48.8% after 24 h. Delivery of fluoride ions was confirmed by a fluoride-sensitive electrode, with release levels resulting in the significant prevention of demineralization of hydroxyapatite discs after treatment with an acidic demineralization solution. Exposure to human gingival fibroblasts and human osteoblasts showed cytocompatibility of the hydrogel, demonstrating the potential for the successful treatment of dental caries in patients.

A clinically relevant formulation for direct administration of nerve specific fluorophores to mitigate iatrogenic nerve injury

Iatrogenic nerve injury significantly affects surgical outcomes. Although intraoperative neuromonitoring is utilized, nerve identification remains challenging and the success of nerve sparing is strongly correlated with surgeon experience levels. Fluorescence guided surgery (FGS) offers a potential solution for improved nerve sparing by providing direct visualization of nerve tissue intraoperatively. However, novel probes for FGS face a long regulatory pathway to achieve clinical translation. Herein, we report on the development of a clinically-viable, gel-based formulation that enables direct administration of nerve-specific probes for nerve sparing FGS applications, facilitating clinical translation via the exploratory investigational new drug (eIND) guidance. The developed formulation possesses unique gelling characteristics, allowing it to be easily spread as a liquid followed by rapid gelling for subsequent tissue hold. Optimization of the direct administration protocol with our gel-based formulation enabled a total staining time of 1-2 min for compatibility with surgical procedures and successful clinical translation.

Thermosensitive Polymers and Thermo-Responsive Liposomal Drug Delivery Systems

Temperature excursions within a biological milieu can be effectively used to induce drug release from thermosensitive drug-encapsulating nanoparticles. Oncological hyperthermia is of particular interest, as it is proven to synergistically act to arrest tumor growth when combined with optimally-designed smart drug delivery systems (DDSs). Thermoresponsive DDSs aid in making the drugs more bioavailable, enhance the therapeutic index and pharmacokinetic trends, and provide the spatial placement and temporal delivery of the drug into localized anatomical sites. This paper reviews the fundamentals of thermosensitive polymers, with a particular focus on thermoresponsive liposomal-based drug delivery systems.

Correia J, Moiseev RV, Cihova M, Gaboriau DCA, Krell J, Khutoryanskiy VV, Stevens MM, Georgiou TK. Investigation of the Thermogelation of a Promising Biocompatible ABC Triblock Terpolymer and Its Comparison with Pluronic F127

Thermoresponsive polymers with the appropriate structure form physical networks upon changes in temperature, and they find utility in formulation science, tissue engineering, and drug delivery. Here, we report a cost-effective biocompatible alternative, namely OEGMA300₁₅-b-BuMA₂₆-b-DEGMA₁₃, which forms gels at low concentrations (as low as 2% w/w); OEGMA300, BuMA, and DEGMA stand for oligo(ethylene glycol) methyl ether methacrylate (MM = 300 g mol^–1), n-butyl methacrylate, and di(ethylene glycol) methyl ether methacrylate, respectively. This polymer is investigated in depth and is compared to its commercially available counterpart, Poloxamer P407 (Pluronic F127). To elucidate the differences in their macroscale gelling behavior, we investigate their nanoscale self-assembly by means of small-angle neutron scattering and simultaneously recording their rheological properties. Two different gelation mechanisms are revealed. The triblock copolymer inherently forms elongated micelles, whose length increases by temperature to form worm-like micelles, thus promoting gelation. In contrast, Pluronic F127’s micellization is temperature-driven, and its gelation is attributed to the close packing of the micelles. The gel structure is analyzed through cryogenic scanning and transmission electron microscopy. Ex vivo gelation study upon intracameral injections demonstrates excellent potential for its application to improve drug residence in the eye.

Engineered implantable vaccine platform for continuous antigen-specific immunomodulation

Cancer vaccines harness the host immune system to generate antigen-specific antitumor immunity for long-term tumor elimination with durable immunomodulation. Commonly investigated strategies reintroduce ex vivo autologous dendritic cells (DCs) but have limited clinical adoption due to difficulty in manufacturing, delivery and low clinical efficacy. To combat this, we designed the "NanoLymph", an implantable subcutaneous device for antigen-specific antitumor immunomodulation. The NanoLymph consists of a dual-reservoir platform for sustained release of immune stimulants via a nanoporous membrane and hydrogel-encapsulated antigens for local immune cell recruitment and activation, respectively. Here, we present the development and characterization of the NanoLymph as well as efficacy validation for immunomodulation in an immunocompetent murine model. Specifically, we established the NanoLymph biocompatibility and mechanical stability. Further, we demonstrated minimally invasive transcutaneous refilling of the drug reservoir in vivo for prolonging drug release duration. Importantly, our study demonstrated that local elution of two drugs (GMCSF and Resiquimod) generates an immune stimulatory microenvironment capable of local DC recruitment and activation and generation of antigen-specific T lymphocytes within 14 days. In summary, the NanoLymph approach can achieve in situ immunomodulation, presenting a viable strategy for therapeutic cancer vaccines.

Study of the Optimal Composition and Storage Conditions of the Fricke-XO-Pluronic F-127 Radiochromic Dosimeter

This paper presents the results of research on the Fricke–XO–Pluronic F–127 dosimeter. It consists of a Fricke dosimetric solution and xylenol orange (XO), which are embedded in a matrix of poly(ethylene oxide)-block-poly(propylene oxide)-block-poly(ethylene oxide) (Pluronic F–127). Upon irradiation, Fe⁺² ions transform into Fe⁺³, forming a colored complex with XO ([XO-Fe]⁺³). The color intensity is related to the dose absorbed. The optimal composition, storage conditions, and radiation-induced performance of the Fricke–XO–Pluronic F–127 dosimeter were investigated. The optimal composition was found to be 1 mM FAS, 50 mM sulfuric acid (H₂SO₄), 0.165 mM XO in 25% Pluronic F–127. The basic features of this dosimeter are discussed, such as dose sensitivity, linear and dynamic dose range, stability before and after irradiation, storage conditions, dose response for irradiation with 6 and 15 MV photons, and batch-to-batch reproducibility. The obtained results showed a certain potential of the Fricke–XO–Pluronic F–127 for radiotherapy dosimetry.

An Innovative Customized Biomimetic Hydrogel for Drug Screening Application Potential: Biocompatibility and Cell Invasion Ability

The ability of Pluronic F127 (PF127) conjugated with tetrapeptide Gly-Arg-Gly-Asp (GRGD) as a sequence of Arg-Gly-Asp (RGD) peptide to form the investigated potential hydrogel (hereafter referred to as 3DG bioformer (3BE)) to produce spheroid, biocompatibility, and cell invasion ability, was assessed in this study. The fibroblast cell line (NIH 3T3), osteoblast cell line (MG-63), and human breast cancer cell line (MCF-7) were cultured in the 3BE hydrogel and commercial product (Matrigel) for comparison. The morphology of spheroid formation was evaluated via optical microscopy. The cell viability was observed through cell counting Kit-8 assay, and cell invasion was investigated via Boyden chamber assay. Analytical results indicated that 3BE exhibited lower spheroid formation than Matrigel. However, the 3BE appeared biocompatible to NIH 3T3, MG-63, and MCF-7 cells. Moreover, cell invasion ability and cell survival rate after invasion through the 3BE was displayed to be comparable to Matrigel. Thus, these findings demonstrate that the 3BE hydrogel has a great potential as an alternative to a three-dimensional cell culture for drug screening applications.

Emerging biomaterial-based strategies for personalized therapeutic in situ cancer vaccines

Landmark successes in oncoimmunology have led to development of therapeutics boosting the host immune system to eradicate local and distant tumors with impactful tumor reduction in a subset of patients. However, current immunotherapy modalities often demonstrate limited success when involving immunologically cold tumors and solid tumors. Here, we describe the role of various biomaterials to formulate cancer vaccines as a form of cancer immunotherapy, seeking to utilize the host immune system to activate and expand tumor-specific T cells. Biomaterial-based cancer vaccines enhance the cancer-immunity cycle by harnessing cellular recruitment and activation against tumor-specific antigens. In this review, we discuss biomaterial-based vaccine strategies to induce lymphocytic responses necessary to mediate anti-tumor immunity. We focus on strategies that selectively attract dendritic cells via immunostimulatory gradients, activate them against presented tumor-specific antigens, and induce effective cross-presentation to T cells in secondary lymphoid organs, thereby generating immunity. We posit that personalized cancer vaccines are promising targets to generate long-term systemic immunity against patient- and tumor-specific antigens to ensure long-term cancer remission.