Injectable hydrogels delivering therapeutic agents for disease treatment and tissue engineering

Abstract

BackgroundInjectable hydrogels have been extensively researched for the use as scaffolds or as carriers of therapeutic agents such as drugs, cells, proteins, and bioactive molecules in the treatment of diseases and cancers and the repair and regeneration of tissues. It is because they have the injectability with minimal invasiveness and usability for irregularly shaped sites, in addition to typical advantages of conventional hydrogels such as biocompatibility, permeability to oxygen and nutrient, properties similar to the characteristics of the native extracellular matrix, and porous structure allowing therapeutic agents to be loaded.Main bodyIn this article, recent studies of injectable hydrogel systems applicable for therapeutic agent delivery, disease/cancer therapy, and tissue engineering have reviewed in terms of the various factors physically and chemically contributing to sol-gel transition via which gels have been formed. The various factors are as follows: several different non-covalent interactions resulting in physical crosslinking (the electrostatic interactions (e.g., the ionic and hydrogen bonds), hydrophobic interactions, π-interactions, and van der Waals forces), in-situ chemical reactions inducing chemical crosslinking (the Diels Alder click reactions, Michael reactions, Schiff base reactions, or enzyme-or photo-mediated reactions), and external stimuli (temperatures, pHs, lights, electric/magnetic fields, ultrasounds, or biomolecular species (e.g., enzyme)). Finally, their applications with accompanying therapeutic agents and notable properties used were reviewed as well.ConclusionInjectable hydrogels, of which network morphology and properties could be tuned, have shown to control the load and release of therapeutic agents, consequently producing significant therapeutic efficacy. Accordingly, they are believed to be successful and promising biomaterials as scaffolds and carriers of therapeutic agents for disease and cancer therapy and tissue engineering.

Self‐healing injectable gelatin hydrogels for localized therapeutic cell delivery

“…Furthermore, therapeutic agents (e.g., proteins, drugs, cells) can be readily mixed into the precursor solution, affording a route for simple and uniform incorporation prior to administration in a potentially cargo‐protective manner. As such, injectable hydrogels are of increasing interest in the field of tissue engineering and therapeutic delivery (Guvendiren, Lu, & Burdick, ; Lee, ; Thambi, Li, & Lee, ).…”

“…As such, injectable hydrogels are of increasing interest in the field of tissue engineering and therapeutic delivery (Guvendiren, Lu, & Burdick, 2012;Lee, 2018;Thambi, Li, & Lee, 2017).…”

Ultrashort Peptide Self-Assembly: Front-Runners to Transport Drug and Gene Cargos

“…The selfassembling peptides are able to serve this resolute as scaffolds. The special focus in the review articles of hydrogels and porous scaffolds remains in controlled release of drugs from the tissue engineering platforms (Boekhoven and Stupp, 2014;Loo et al, 2015;Rambhia and Ma, 2015;Koutsopoulos, 2016;Banerjee et al, 2018;Lee, 2018;Inaba and Matsuura, 2019). One of the very important areas in tissue engineering is to explore the ways, to modify the properties of the materials, including mechanical and chemical functionality through changes at the sequence level to influence the cell behavior and modulate the scaffold stability (Zhou et al, 2014).…”

Synthesis and Evaluation of a Thermoresponsive Degradable Chitosan-Grafted PNIPAAm Hydrogel as a “Smart” Gene Delivery System

“…Hydrogel that can be administered through minimally invasive delivery is an attractive proposition that can enhance patient convenience, ease surgical administration, and reduce costs associated with surgery [11]. Injectable hydrogels can readily mold into the shape of the surgical cavity and adhere to the surrounding tissues during hydrogel formation, which facilitates treatment of any non-standard geometry [3].…”