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Researchers have developed a new method of injecting healthy cells into damaged eyes. The technique could point the way toward new treatments with the potential to reverse forms of vision loss that are currently incurable.

Heart muscle becomes damaged and cardiac function is affected when blood vessels feeding the heart are blocked. A new stem-cell-carrying hydrogel helps mice recover from this condition, called myocardial infarction, by stimulating formation of new blood vessels. Developed by a team of scientists at Kansai University in Japan, the stem cell delivery system is described in the journal Science and Technology of Advanced Materials.

“Adhesion of soft materials, especially hydrogels, greatly attracted our research interests, because the state-of-the-art adhesion of hydrogels was fairly weak and often led to failures,” Zhao says. “In 2015, we proposed the first general strategy to achieve tough adhesion for diverse hydrogels and other materials.”
Like humans, hydrogels are made out of polymers and water. The similarities in mechanical and electrical properties make biological tissue and hydrogels compatible, opening up a world of biomedical applications. Now, Zhao and Yuk could further integrate hydrogels within various materials, devices, and even the human body with unprecedented robustness.

The researchers found strong correlation between the stiffness of hydrogels, which mimic intestinal mucus, and how well a diarrhea-causing strain of E. coli adhered to and aggregated atop the epithelial cells that normally line the intestines. They reported that softer hydrogels promoted "significantly greater bacterial adhesion," which they attribute to mucus and other extracellular matrix components expressed by the cells.

Instead of synthetic or biologic materials commonly used for these types of injuries, a team led by Robert Mauck, director of the McKay Lab and a professor of orthopedic surgery and bioengineering, has used a combination of a magnetic liquid and three-dimensional hydrogel solution which could conform to the particular nuances of an injury within the body.

With all the advances in tissue engineering for construction of fully functional skin tissue, complete regeneration of chronic wounds is still challenging. Since immune reaction to the tissue damage is critical in regulating both the quality and duration of chronic wound healing cascade, strategies to modulate the immune system are of importance. Generally, in response to an injury, macrophages switch from pro-inflammatory to an anti-inflammatory phenotype. Therefore, controlling macrophages’ polarization has become an appealing approach in regenerative medicine. Recently, hydrogels-based constructs, incorporated with various cellular and molecular signals, have been developed and utilized to adjust immune cell functions in various stages of wound healing.

Rational design of hydrogels that balance processability and extracellular matrix (ECM) biomimicry remains a challenge for tissue engineering and biofabrication. Hydrogels suitable for biofabrication techniques, yet tuneable to match the mechanical (static and dynamic) properties of native tissues remain elusive. Dynamic covalent hydrogels possessing shear-thinning/self-healing (processability) and time-dependent cross-links (mechanical properties) provide a potential solution, yet can be difficult to rationally control.

Unlike traditional ways of treating cancer, which target rapidly dividing cells as well as healthy ones, “Hydrogels allow you to give targeted doses to the affected areas only,” say De Angulo and Ayoola Smith, a lecturer at the University of Lagos in Nigeria. Smith specializes in pharmacognosy, the study of drugs made from plants and natural sources.

Hydrogels are everywhere. They are water-loving polymers that can absorb and retain water, and can be found in such everyday consumer products such as soft contact lenses, disposable diapers, certain foods, and even in agricultural applications. They are also extremely useful in several medical applications due to their high degree of biocompatibility and their ability to eventually degrade and be reabsorbed into the body.

Injecting hydrogels containing stem cell or exosome therapeutics directly into the pericardial cavity could offer a less invasive, less costly, and more effective way to treat cardiac injury, according to new research.

Many features of extracellular matrices, e.g., self-healing, adhesiveness, viscoelasticity, and conductivity, are associated with the intricate networks composed of many different covalent and non-covalent chemical bonds. Whereas a reductionism approach would have the limitation to fully recapitulate various biological properties with simple chemical structures, mimicking such sophisticated networks by incorporating many different functional groups in a macromolecular system is synthetically challenging. Herein, we propose a strategy of convergent synthesis of complex polymer networks to produce biomimetic electroconductive liquid metal hydrogels.

Hydrogels are three-dimensional networks of crosslinked polymers. However, current hydrogel wound dressings are made up of synthetic polymers that are biologically inert and do not drive hosts' biology toward wound healing. Such treatment modality is particularly paradoxical for severe wounds where exogeneous mediators are critical for regeneration. Recently, the incorporation of stem cells has been proposed to confer inert dressings with biologic properties. The cells possess the ability to release paracrine wound-healing factors and differentiate into multiple skin cell types to replace lost tissues. In order to replicate aspects of the stem cells' native extracellular matrix (ECM) environment, researchers are turning to natural polymers that are more cytocompatible.

Hydrogels are polymer materials made mostly from water. They can be used in a wide range of medical and other applications. However, previous incarnations of the materials suffered from repeated mechanical stress and would easily become deformed. A novel crystal that can reversibly form and deform, allows hydrogels to rapidly recover from mechanical stress. This opens up the use of such biocompatible materials in the field of artificial joints and ligaments.

The final product is not a gel like jam or a hair gel. Rather, these hydrogels are synthesized in the form of thin foil sheets. The sheets can be shaped with scissors or a knife, then placed on the surface one wishes to clean. (The gel adheres easily even to vertical surfaces like walls.) Leave a sheet for a few minutes—not too long—and then just peel it off. The over-paint will be softened and swollen, and it can be easily removed by gentle mechanical action. Should you accidentally leave the gel on too long, Michele Baglioni advised just letting it dry as the solvents and water evaporate, being careful not to try to wipe anything away. This should avoid any harm to the underlying painting.

3D-printing tough conductive hydrogels (TCHs) with complex structures is still a challenging task in related fields due to their inherent contrasting multinetworks, uncontrollable and slow polymerization of conductive components. Here we report an orthogonal photochemistry-assisted printing (OPAP) strategy to make 3D TCHs in one-pot via the combination of rational visible-light-chemistry design and reliable extrusion printing technique. This orthogonal chemistry is rapid, controllable, and simultaneously achieve the photopolymerization of EDOT and phenol-coupling reaction, leading to the construction of tough hydrogels in a short time (tgel ~30 s).

The widespread use of high-speed and high-energy weapons in modern warfare has led to an increasing incidence of explosive injuries. For such wounds as well as those incurred in disasters and accidents, severe hemorrhage is the leading cause of death.

Light-responsive hydrogels are an emerging class of materials used for developing noninvasive, noncontact, precise and controllable medical devices in a wide range of biomedical applications, including photothermal therapy, photodynamic therapy, drug delivery and regenerative medicine.

The ability of hydrogels to absorb water arises from hydrophilic functional groups attached to the polymeric backbone, while their resistance to dissolution arises from cross-links between network chains. Many materials, both naturally occurring and synthetic, fit the definition of hydrogels. Natural hydrogels include collagen, silk fibroin, hyaluronic acid, chitosan, alginate and hydrogels derived from decellularized tissues. Their unique properties include: biocompatibility, biodegradability, low cytotoxicity, the possibility to tailor the hydrogel into an injectable gel and their similarity to physiological environment.