Combining microfluidics and coaxial 3D-bioprinting for the manufacturing of diabetic wound healing dressings

Development of dual drug loaded-hydrogel scaffold combining microfluidics and coaxial 3D-printing for intravitreal implantation

Treating diabetic retinopathy (DR) effectively is challenging, aiming for high efficacy with minimal discomfort. While intravitreal injection is the current standard, it has several disadvantages. Implantable systems offer an alternative, less invasive, with long-lasting effects drug delivery system (DDS). The current study aims to develop a soft, minimally invasive, biodegradable, and bioadhesive material-based hydrogel scaffold to prevent common issues with implants. A grid-shaped scaffold was created using coaxial 3D printing (3DP) to extrude two bioinks in a single filament. The scaffold comprises an inner core of curcumin-loaded liposomes (CUR-LPs) that prepared by microfluidics (MFs) embedded in a hydrogel of hydroxyethyl cellulose (HEC), and an outer layer of hyaluronic acid-chitosan matrix with free resveratrol (RSV), delivering two Sirt1 agonists synergistically activating Sirt1 downregulated in DR. Optimized liposomes, prepared via MFs, exhibit suitable properties for retinal delivery in terms of size (<200 nm), polydispersity index (PDI) (<0.3), neutral zeta potential (ZP), encapsulation efficiency (∼97 %), and stability up to 4 weeks. Mechanical studies confirm scaffold elasticity for easy implantation. The release profiles show sustained release of both molecules, with different patterns related to different localization of the molecules. RSV released initially after 30 min with a total release more than 90 % at 336 h. CUR release starts after 24 h with only 4.78 % of CUR released before and gradually released thanks to its internal localization in the scaffold. Liposomes and hydrogels can generate dual drug-loaded 3D structures with sustained release. Microscopic analysis confirms optimal distribution of liposomes within the hydrogel scaffold. The latter resulted compatible in vitro with human retinal microvascular endothelial cells up to 72 h of exposition. The hydrogel scaffold, composed of hyaluronic acid and chitosan, shows promise for prolonged treatment and minimally invasive surgery.

Lipid-based nanosystems for wound healing

INTRODUCTION

Wounds, resulting from traumas, surgery, burns or diabetes, are important medical problems due to the complexity of wound healing process regarding healing times and healthcare costs. Nanosystems have emerged as promising candidates in this field thank to their properties and versatile applications in drugs delivery.

AREAS COVERED

Lipid-based nanosystems (LBN) are described for wound treatment, highlighting their different behaviors when interacting with the cutaneous tissue. The role of nanosystems in delivering mostly natural compounds on skin as well as the technological and engineering strategies to increase their efficiency in wound healing effect are reviewed. Finally, in vitro, ex-vivo and in vivo studies are reported.

EXPERT OPINION

LBN have shown promise in addressing the challenges of wound healing as they can improve the stability of drugs used in wound therapy, leading to higher efficacy and fewer adverse effects as compared to traditional formulations. LBNs being involved in the inflammatory and proliferation stages of the wound healing process, enable the modification of wound healing through multiple ways. In addition, the use of new technologies, including 3D bioprinting and photobiomodulation, may lead to potential breakthroughs in wound healing. This would provide clinicians with more potent forms of therapy for wound healing.

3D-Bioprinted Skin Tissues for Improving Wound Healing: Current Status and Perspective

Advancements in tissue engineering enable the fabrication of complex and functional tissues or organs. In particular, bioprinting enables controlled and accurate deposition of cells, biomaterials, and growth factors to create complex 3D skin constructs specific to a particular individual. Despite these advancements, challenges such as vascularization, long-term stability, and regulatory considerations hinder the clinical translation of bioprinted skin constructs. This chapter focuses on such approaches using advanced biomaterials and bioprinting techniques to overcome the current barriers in wound-healing studies. Moreover, it addresses current obstacles in wound-healing studies, highlighting the need for continued research and innovation to overcome these barriers and facilitate the practical utilization of bioprinted skin constructs in clinical settings.

3D printing and bioprinting in the battle against diabetes and its chronic complications

Diabetes is a metabolic disorder characterized by high blood sugar. Uncontrolled blood glucose affects the circulatory system in an organism by intervening blood circulation. The high blood glucose can lead to macrovascular (large blood vessels) and microvascular (small blood vessels) complications. Due to this, the vital organs (notably brain, eyes, feet, heart, kidneys, lungs and nerves) get worsen in diabetic patients if not treated at the earliest. Therefore, acquiring treatment at an appropriate time is very important for managing diabetes and other complications that are caused due to diabetes. The root cause for the occurrence of various health complications in diabetic patients is the uncontrolled blood glucose levels. This review presents a consolidated account of the applications of various types of three-dimensional (3D) printing and bioprinting technologies in treating diabetes as well as the complications caused due to impaired blood glucose levels. Herein, the development of biosensors (for the diagnosis), oral drug formulations, transdermal drug carriers, orthotic insoles and scaffolds (for the treatment) are discussed. Next to this, the fabrication of 3D bioprinted organs and cell-seeded hydrogels (pancreas engineering for producing insulin and bone engineering for managing bone defects) are explained. As the final application, 3D bioprinting of diabetic disease models for high-throughput screening of ant-diabetic drugs are discussed. Lastly, the challenges and future perspective associated with the use of 3D printing and bioprinting technologies against diabetes and its related chronic complications have been put forward.

Recent Developments in 3D-(Bio)printed Hydrogels as Wound Dressings

Wound healing is a physiological process occurring after the onset of a skin lesion aiming to reconstruct the dermal barrier between the external environment and the body. Depending on the nature and duration of the healing process, wounds are classified as acute (e.g., trauma, surgical wounds) and chronic (e.g., diabetic ulcers) wounds. The latter take several months to heal or do not heal (non-healing chronic wounds), are usually prone to microbial infection and represent an important source of morbidity since they affect millions of people worldwide. Typical wound treatments comprise surgical (e.g., debridement, skin grafts/flaps) and non-surgical (e.g., topical formulations, wound dressings) methods. Modern experimental approaches include among others three dimensional (3D)-(bio)printed wound dressings. The present paper reviews recently developed 3D (bio)printed hydrogels for wound healing applications, especially focusing on the results of their in vitro and in vivo assessment. The advanced hydrogel constructs were printed using different types of bioinks (e.g., natural and/or synthetic polymers and their mixtures with biological materials) and printing methods (e.g., extrusion, digital light processing, coaxial microfluidic bioprinting, etc.) and incorporated various bioactive agents (e.g., growth factors, antibiotics, antibacterial agents, nanoparticles, etc.) and/or cells (e.g., dermal fibroblasts, keratinocytes, mesenchymal stem cells, endothelial cells, etc.).

Revolutionizing biomedicine: advancements, applications, and prospects of nanocomposite macromolecular carbohydrate-based hydrogel biomaterials: a review

Nanocomposite hydrogel biomaterials represent an exciting Frontier in biomedicine, offering solutions to longstanding challenges. These hydrogels are derived from various biopolymers, including fibrin, silk fibroin, collagen, keratin, gelatin, chitosan, hyaluronic acid, alginate, carrageenan, and cellulose. While these biopolymers possess inherent biocompatibility and renewability, they often suffer from poor mechanical properties and rapid degradation. Researchers have integrated biopolymers such as cellulose, starch, and chitosan into hydrogel matrices to overcome these limitations, resulting in nanocomposite hydrogels. These innovative materials exhibit enhanced mechanical strength, improved biocompatibility, and the ability to finely tune drug release profiles. The marriage of nanotechnology and hydrogel chemistry empowers precise control over these materials' physical and chemical properties, making them ideal for tissue engineering, drug delivery, wound healing, and biosensing applications. Recent advancements in the design, fabrication, and characterization of biopolymer-based nanocomposite hydrogels have showcased their potential to transform biomedicine. Researchers are employing strategic approaches for integrating biopolymer nanoparticles, exploring how nanoparticle properties impact hydrogel performance, and utilizing various characterization techniques to evaluate structure and functionality. Moreover, the diverse biomedical applications of these nanocomposite hydrogels hold promise for improving patient outcomes and addressing unmet clinical needs.