Cell proliferation influenced by matrix compliance of gelatin grafted poly(d,l-Lactide) three dimensional scaffolds

Recent trends in diabetic wound healing with nanofibrous scaffolds

There is an emphasis in this review on nanofibrous scaffolds (NFSs) in diabetic wound healing, as well as their mechanisms and recent advancements. Diabetes-related complex wounds pose an important problem to humanity, due to the fact that their chronic nature can lead to serious complications including sepsis and amputations. Despite the fact that there are certain therapy options available for diabetic wound healing, these options are either ineffective or intrusive, making clinical intervention difficult. Clinical research is also challenged by the emergence of bacterial resistance to standard antibiotics. However, research into nanotechnology, in particular NFSs, is growing swiftly and has a positive impact on the treatment of diabetic wounds. For instance, SpinCare™, developed by Nanomedic Technologies Ltd, has successfully finished clinical testing and can re-epithelialize second-degree burns and chronic diabetic wounds in 7 and 14 days, respectively. In this review, we discussed homologous studies as well as other recent research studies on diabetic wound healing using NFSs.

Mussel-Inspired Adhesive Hydrogels Based on Laponite-Confined Dopamine Polymerization as a Transdermal Patch

Transdermal patch for local drug delivery has attained huge attention as an attractive alternative to existing drug delivery techniques as it is painless and user-friendly. However, most adhesive hydrogels either do not have adequate adhesion with the skin or cause discomfort while being removed from the skin surface due to excessive adhesion. To address this challenge, we developed an adhesive hydrogel based on laponite-confined dopamine polymerization as a transdermal patch. Laponite RDS nanoclay was used to control the hydrogel's viscous behavior and dopamine polymerization. The laponite polymerized polydopamine (l-PDA) was incorporated into poly(vinyl alcohol) (PVA) to make the PVA-l-PDA hydrogel. The laponite-confined polymerization improved the hydrogels' water contact angle and adhesion strength. The adhesion strength of the PVA-l-PDA hydrogel was adequate to adhere to the evaluated goat skin, glass, and polypropylene surfaces. Notably, the PVA-l-PDA hydrogel was easy to peel off from the skin. Further, we evaluated the drug release profile in goat skin using lidocaine as a model drug. We observed the controlled release of lidocaine from the PVA-l-PDA hydrogel compared to the PVA-PDA hydrogel. In addition, the nanoclay-confined adhesive hydrogel did not show any cytotoxic effect in fibroblasts. Altogether, PVA-l-PDA hydrogels offer appropriate adhesive strength, toughness, and biocompatibility. Thus, the PVA-l-PDA hydrogel has the potential to be an efficient transdermal patch.

Biodegraded PCl and gelatin fabricated vascular patch in rat aortic and inferior vena cava angioplasty

Novel synthetic prosthesis materials for patch angioplasty are continuously under development and optimization. When a nonwoven-based gelatin membrane is coupled with an electrospun layer of polycaprolactone (PCL), these biohybrid polymer membranes (BHMs) possess higher mechanical properties in aqueous environments. We hypothesized that BHMs can also be used as vascular patches, and we tested our hypothesis in a rat IVC venoplasty and aortic arterioplasty model. Patch venoplasty and arterioplasty were performed in SD rats (200 g), the patches were harvested at day 14, and samples were analyzed by immunohistochemistry and immunofluorescence. The BHM patches were almost degraded, with few parts remaining after 14 days. There was a line of CD34- and nestin-positive cells on the endothelium, with some cells were CD34 and nestin dual-positive, macrophages and leukocytes also participated in the patch healing process. There were PCNA-positive cells in the neointima and peri-patch area, with some cells were also PCNA and α-actin dual-positive. Arterial neointimal endothelial cells were Ephrin-B2- and dll-4-positive, and venous neointimal endothelial cells were Eph-B4- and COUP-TFII-positive. BHM shares a similar healing process like other patch materials, and BHM may have potential applications in vascular surgery.

Nanohybrid-Reinforced Gelatin-Ureidopyrimidinone-Based Self-healing Injectable Hydrogels for Tissue Engineering Applications

The traditional hydrogels are prone to break due to the applied stress. The deformation of the implanted hydrogels would result in the loss of structural integrity, leading to the failure of hydrogel functionalities and tissue regeneration. Self-healing hydrogels (AG-UPy), composed of oxidized alginate and ureidopyrimidinone-functionalized gelatin (G-UPy), were developed to address this challenge. These self-healing hydrogels possess two independent healing mechanisms, viz., Schiff base formation and UPy dimerization. These hydrogels were compared with oxidized alginate-gelatin (AG) hydrogels. AG-UPy hydrogels showed effective self-healing in a short time (about 2 min) after applying 800% strain, wherein recovery was not achieved with the AG hydrogel. However, the shear-thinning property of UPy made the AG-UPy hydrogel mechanically weaker than the AG hydrogel. To improve the mechanical strength of the AG-UPy hydrogel, we impregnated poly(ethylene glycol)-poly(urethane)/cloisite nanohybrid (PEG-PU/C) to prepare the AG-UPy/PEG-PU/C hydrogel. The incorporation of PEG-PU/C resulted in a 20-fold increase in the compression strength compared to that of the AG-UPy hydrogel. The AG-UPy/PEG-PU/C hydrogels also showed rapid self-healing. Incorporating the nanohybrid improved the cell proliferation by 2- and 1.25-fold compared to that of the AG and AG-UPy hydrogels, respectively. Therefore, PEG-PU/C combined with the UPy-functionalized polymer could be used to modulate mechanical strength and self-healing and enhance cell proliferation.

Recent Advances in Scaffolding from Natural-Based Polymers for Volumetric Muscle Injury

Volumetric Muscle Loss (VML) is associated with muscle loss function and often untreated and considered part of the natural sequelae of trauma. Various types of biomaterials with different physical and properties have been developed to treat VML. However, much work remains yet to be done before the scaffolds can pass from the bench to the bedside. The present review aims to provide a comprehensive summary of the latest developments in the construction and application of natural polymers-based tissue scaffolding for volumetric muscle injury. Here, the tissue engineering approaches for treating volumetric muscle loss injury are highlighted and recent advances in cell-based therapies using various sources of stem cells are elaborated in detail. An overview of different strategies of tissue scaffolding and their efficacy on skeletal muscle cells regeneration and migration are presented. Furthermore, the present paper discusses a wide range of natural polymers with a special focus on proteins and polysaccharides that are major components of the extracellular matrices. The natural polymers are biologically active and excellently promote cell adhesion and growth. These bio-characteristics justify natural polymers as one of the most attractive options for developing scaffolds for muscle cell regeneration.

Gelatin grafted poly(D,L-lactide) as an inhibitor of protein aggregation: An in vitro case study

Amyloids are a group of proteins that are capable of forming aggregated amyloid fibrils, which is responsible for many neurodegenerative diseases including Alzheimer's disease (AD). In our previous study, synthesis and characterization of star-shaped poly(D,L-lactide)-b-gelatin (ss-pLG) have been reported. In the present work, we have extended our work to study ss-pLG against protein aggregation. To the best of our knowledge, this is the first report on the inhibition of amyloid fibrillation by protein grafted poly(D,L-lactide). Bovine serum albumin (BSA) was chosen as the model protein, which readily forms fibril under high temperature. We found that ss-pLG efficiently suppressed the fibril formation of BSA compared with gelatin (Gel), which was supported by Thioflavin T assay, circular dichroism (CD) spectroscopy and atomic force microscopy (AFM). In addition, ss-pLG significantly curtailed amyloid-induced hemolysis. We also found that incubation of ss-pLG with neuroblastoma cells (MC65) protected the cells from fibril-induced toxicity. The rescuing efficiency of ss-pLG was better than Gel, which could be attributed to the reduced lamella thickness in branched ss-pLG. These results suggest the significance of gelatin grafting, which probably allows gelatin to interact with the key residues of the amyloidogenic core of BSA effectively.

Nanohybrid Scaffold of Chitosan and Functionalized Graphene Oxide for Controlled Drug Delivery and Bone Regeneration

Nanohybrid scaffolds of chitosan have been designed for controlled drug delivery and bone regeneration. Sulfonated graphene oxide has been used to develop the nanohybrids. Nanohybrid scaffolds show highly hydrophilic character and greater mechanical strength as compared to pure chitosan. Nanohybrid scaffolds show an interconnected uniform porous network structure exhibiting sustained release kinetics of the antibacterial drug, tetracycline hydrochloride. Nanohybrids are found to be highly biocompatible in nature and are able to support and proliferate MG63 osteoblast cells and thereby induce bone tissue regeneration. The in-vivo bone healing study shows that the developed nanohybrid scaffolds have the potential to regenerate the bone faster without any side effects as compared to pure scaffolds. Hence, the developed nanohybrid scaffold has good potential as a controlled drug delivery vehicle and in bone tissue engineering for faster healing.

The thickness of poly-phenoxyethyl methacrylate brush interferes with cellular behavior and function of myofibers

Introducing or grafting molecules onto biomaterial surfaces to regulate muscle cell destination via biophysical cues is one of the important steps for biomaterial design in muscle tissue engineering. Therefore, it is important to understand the interaction between myoblasts and myofibers with substrates modified by biomimetic layer with different thicknesses. In this study, we used a surface-induced atom transfer radical polymerization method to synthetize and graft poly-phenoxyethyl methacrylate (PHEMA) brushes having different lengths on the glass substrates. C2C12 myoblasts were seeded on the PHEMA brushes and differentiated using horse serum, for analyzing the sensibility of muscle cells to feel environment changing, and further investigating whether the depths of grafting layer on the biomaterial surface are important factors in regulating muscle cell behaviors. Our results demonstrated that on the thicker PHEMA brushes surface (200 and 450 nm), C2C12 myoblasts showed a better survival and proliferation and were favorable for cell fusion and myotube formation. Furthermore, myofibers survived on the thicker brushes were more functional and upregulated cytoskeleton proteins (tubulin, vimentin, and vinculin) and FAK levels, and enhanced the expression levels for mechanical stress molecules (HGF, NOS-1, and c-Met). These results suggest that grafting thickness of PHEMA layer on the substrate led to the myoblasts/myofiber behavior change, which would be valuable for the design and preparation of the modified layer on muscle tissue engineering scaffolds. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1264-1272, 2019.