In situ forming injectable hydrogels for drug delivery and wound repair

Abstract

Hydrogels have been utilized in regenerative applications for many decades because of their biocompatibility and similarity in structure to the native extracellular matrix. Initially, these materials were formed outside of the patient and implanted using invasive surgical techniques. However, advances in synthetic chemistry and materials science have now provided researchers with a library of techniques whereby hydrogel formation can occur in situ upon delivery through standard needles. This provides an avenue to minimally invasively deliver therapeutic payloads, fill complex tissue defects, and induce the regeneration of damaged portions of the body. In this review, we highlight these injectable therapeutic hydrogel biomaterials in the context of drug delivery and tissue regeneration for skin wound repair.

Non‐Newtonian Polymer–Nanoparticle Hydrogels Enhance Cell Viability during Injection

“…Hydrogels are readily suited for biological applications because of their tissue‐like mechanical properties, high water content, biocompatibility, and stimuli‐responsiveness. In the field of drug delivery, hydrogels provide sustained and temporally controlled delivery of drugs in localized regions, reducing off‐target toxicity and increasing clinical efficacy …”

“…In the field of drug delivery, hydrogels provide sustained and temporally controlled delivery of drugs in localized regions, reducing off-target toxicity and increasing clinical efficacy. [4,[6][7][8][9] Administrating cells through highgauge needles is becoming more common due to the development of cell therapies [10] and 3D bioprinting technologies [3] ; however, previous studies have shown that injecting cells through clinically relevant needles often results in cell death and poor cell viability. [11] Targeted cell delivery is often desired for medical application, but the therapeutic effect of the treatment is decreased because many of the cells injected in saline solutions (i.e., phosphate-buffered saline [PBS]) are regurgitated due to the pressure in the tissue and fluid flow away from the injection site.…”

Dynamic Hydrogels from Host–Guest Supramolecular Interactions

“…These materials can furthermore respond to a variety of environmental stimuli with changes in their chemical, biological, mechanical, or macroscale properties . There are multifarious biomedical applications wherein hydrogels are used, including oral drug formulations, injectable drug depots, in situ forming biomaterials, and contact lenses, among many others . For an appreciation of this field, our reader is encouraged to consult many excellent papers and reviews, including those cited here, which offer exhaustive coverage of the synthesis, preparation, characterization, and use of hydrogels for an assortment of biomedical applications.…”

Enhanced In Vivo Delivery of Stem Cells using Microporous Annealed Particle Scaffolds

“…Localized delivery of stem cells using biomaterials can mitigate these issues . An ideal material should not only enable minimally invasive delivery by injection, and retain cells after transplantation to achieve sustained function, but also create an artificial stem cell niche in situ for higher efficacy and longer maintenance of the therapy . Specifically, the biomaterial should provide suitable biophysical and biochemical microenvironmental cues for enhanced control of cell function in vivo .…”

“…Specifically, the biomaterial should provide suitable biophysical and biochemical microenvironmental cues for enhanced control of cell function in vivo . However, current injectable biomaterials suffer from ineffective modulation or lack of porosity for mass transport, cell motility, proliferation, cell–cell adhesion, or new tissue formation …”