Albumin-based hydrogels for regenerative engineering and cell transplantation

Albumin, the most abundant plasma protein in mammals, is a versatile and easily obtainable biomaterial. It is pH and temperature responsive, dissolvable in high concentrations and gels readily in defined conditions. This versatility, together with its inexpensiveness and biocompatibility, makes albumin an attractive biomaterial for biomedical research and therapeutics. So far, clinical research in albumin has centered mainly on its use as a carrier molecule or nanoparticle to improve drug pharmacokinetics and delivery to target sites. In contrast, research in albumin-based hydrogels is less established albeit growing in interest over recent years. In this minireview, we report current literature and critically discuss the synthesis, mechanical properties, biological effects and uses, biodegradability and cost of albumin hydrogels as a xeno-free, customizable, and transplantable construct for tissue engineering and regenerative medicine.     

An Acquired and Endogenous Glycocalyx Forms a Bidirectional “Don’t Eat” and “Don’t Eat Me” Barrier to Phagocytosis

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Finite Element Model to Reproduce the Effect of Pre-Stress and Needle Insertion Velocity During Infusions into Brain Phantom Gel

Convection-enhanced delivery (CED) is a technique to bypass the blood-brain barrier and deliver therapeutic agents into the brain. However, animal studies and preliminary clinical trials have reported reduced efficacy to transport drugs in specific regions, attributed mainly to backflow, in which an annular zone is formed outside the catheter and the fluid preferentially flows toward the surface of the brain rather than through the tissue toward the targeted area. In this study, a finite element model of backflow was updated by implementing the pre-stress generated during needle insertion, which allows considering the effect of needle insertion velocity during CED infusions in agarose gel. The nonlinear mechanical properties of the agarose solutions were obtained by fitting experimental data from stress-relaxation tests. Additional experimental measurements of backflow lengths were used to adjust the pre-stress model. The developed model was able to reproduce changes of backflow length under different insertions velocities and flow rates. These findings reveal the relevance of considering the pre-stress in the tissue located around the needle surface during CED infusions into the brain.     

Hydrogel baits pose minimal risk to non-target insects and beneficial species

Invasive ants are a significant pest around the world and have negative impact on natural and agricultural environments. Chemical control is mainly accomplished with residual sprays and toxic baits. Hydrogel baits are a novel bait formulation that has proven highly effective against multiple invasive ant species, but potential non-target effects have not been investigated. The baits are typically saturated in 25% sucrose solution which makes them attractive to foraging ants and potentially non-target organisms such as pollinators. The objective of the current study was to perform field studies to assess the potential attractiveness of hydrogel baits to various pollinating and non-pollinating arthropods in a variety of ecosystems, including tallgrass prairies, urban pollinator gardens, and commercial apiaries. The study focused on social Hymenoptera as pesticides are acutely toxic to various Hymenoptera and have been implicated as one of the contributing factors in pollinator declines. Results show that Diptera were overwhelmingly the most common visitors and accounted for >40% of all visitors. Other common groups included beetles and yellowjackets. Common pollinating insects such as honeybees, solitary bees, and butterflies rarely visited the baits and accounted for ca. 3% of all visits and were never found on ground baits. Results show that the risk to pollinators is relatively low; most arthropods attracted to the baits were taxa that are extremely abundant, not of conservation concern, and in some cases pestiferous or invasive. The deployment of hydrogels for invasive ant control in areas where multiple invasive insect taxa are present may have the additional benefit of controlling multiple pests.