Preparation of photocrosslinked fish elastin polypeptide/microfibrillated cellulose composite gels with elastic properties for biomaterial applications

Photocrosslinked Fish Collagen Peptide/Chitin Nanofiber Composite Hydrogels from Marine Resources: Preparation, Mechanical Properties, and an In Vitro Study

Fish collagen peptide (FCP) is a water-soluble polymer with easy accessibility, bioactivity, and reactivity due to its solubility. The gelation of FCP can be carried out by chemical crosslinking, but the mechanical strength of FCP hydrogel is very low because of its intrinsically low molecular weight. Therefore, the mechanical properties of FCP gel should be improved for its wider application as a biomaterial. In this study, we investigated the mechanical properties of M-FCP gel in the context of understanding the influence of chitin nanofibers (CHNFs) on FCP hydrogels. FCP with a number average molecular weight (M_n) of ca. 5000 was reacted with glycidyl methacrylate (GMA) and used for the preparation of photocrosslinked hydrogels. Subsequently, composite hydrogels of methacrylate-modified FCP (M-FCP) and CHNF were prepared by the photoirradiation of a solution of M-FCP containing dispersed CHNF at an intensity of ~60 mW/cm² for 450 s in the presence of 2-hydroxy-1-[4-(hydroxyethoxy)phenyl]-2-methyl-1-propanone (Irgacure 2959) as a photoinitiator. Compression and tensile tests of the FCP hydrogels were carried out using a universal tester. The compression and tensile strength of the hydrogel increased 10-fold and 4-fold, respectively, by the addition of 0.6% CHNF (20% M-FCP), and Young's modulus increased 2.5-fold (20% M-FCP). The highest compression strength of the M-FCP/CHNF hydrogel was ~300 kPa. Cell proliferation tests using fibroblast cells revealed that the hydrogel with CHNF showed good cell compatibility. The cells showed good adhesion on the M-FCP gel with CHNF, and the growth of fibroblast cells after 7 days was higher on the M-FCP/CHNF gel than on the M-FCP gel without CHNF. In conclusion, we found that CHNF improved the mechanical properties as well as the fibroblast cell compatibility, indicating that M-FCP hydrogels reinforced with CHNF are useful as scaffolds and wound-dressing materials.

Extraction and Characterization of Collagen from Elasmobranch Byproducts for Potential Biomaterial Use

With the worldwide increase of fisheries, fish wastes have had a similar increase, alternatively they can be seen as a source of novel substances for the improvement of society's wellbeing. Elasmobranchs are a subclass fished in high amounts, with some species being mainly bycatch. They possess an endoskeleton composed mainly by cartilage, from which chondroitin sulfate is currently obtained. Their use as a viable source for extraction of type II collagen has been hypothesized with the envisaging of a biomedical application, namely in biomaterials production. In the present work, raw cartilage from shark (Prionace glauca) and ray (Zeachara chilensis and Bathyraja brachyurops) was obtained from a fish processing company and submitted to acidic and enzymatic extractions, to produce acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC). From all the extractions, P. glauca PSC had the highest yield (3.5%), followed by ray ASC (0.92%), ray PSC (0.50%), and P. glauca ASC (0.15%). All the extracts showed similar properties, with the SDS-PAGE profiles being compatible with the presence of both type I and type II collagens. Moreover, the collagen extracts exhibited the competence to maintain their conformation at human basal temperature, presenting a denaturation temperature higher than 37 °C. Hydrogels were produced using P. glauca PSC combined with shark chondroitin sulfate, with the objective of mimicking the human cartilage extracellular matrix. These hydrogels were cohesive and structurally-stable at 37 °C, with rheological measurements exhibiting a conformation of an elastic solid when submitted to shear strain with a frequency up to 4 Hz. This work revealed a sustainable strategy for the valorization of fisheries' by-products, within the concept of a circular economy, consisting of the use of P. glauca, Z. chilensis, and B. brachyurops cartilage for the extraction of collagen, which would be further employed in the development of hydrogels as a proof of concept of its biotechnological potential, ultimately envisaging its use in marine biomaterials to regenerate damaged cartilaginous tissues.

Lapatinib inhibits doxorubicin induced migration of HER2-positive breast cancer cells

Inflammatory breast cancer (IBC) is an uncommon and highly aggressive form of breast cancer. The disease is characterized by rapid progression with approximately 50% of IBC patients to have human epidermal growth factor receptor 2 (HER2) amplification. HER2-positive IBC is associated with unfavourable prognosis and increased risk of brain metastasis. Ironically, HER2-positive metastatic breast cancer is still prevalent where therapeutic targeting of HER2-receptor is well developed. In addition, the ability to accurately predict the risk of metastatic potential in these cells poses a substantial challenge. Lapatinib (Lap), a dual kinase inhibitor of HER2 and epidermal growth factor receptor is used in the treatment of advanced HER-2 positive breast cancers and is currently being evaluated in the adjuvant setting. In this study, we report the effectiveness of Lap in the suppression of low-dose response to doxorubicin (Dox) in HER2-positive SKBR3 cells. Upon treatment of SKBR3 cells with 0.1 µM of Dox, the cell viability was significantly increased as compared to the human mammary fibroblasts, and triple-negative human breast cancer MDA-MB-231 cells. Interestingly, the effect of 0.1 µM Dox revealed morphological changes consistent with a significant increase in the formation of prominent F-actin filaments and mitochondrial spread compared with the control SKBR3 cells. Furthermore, an enhanced migration was also evident in these cells. However, a combinational dose of 0.1 µM Dox + 5 µM Lap suppressed the observed phenotypic changes in the 0.1 µM Dox treated SKBR3 cells. There was a significant difference in the prominent F-actin filaments and the mitochondrial spread compared with the 0.1 µM Dox versus combination regimen of 0.1 µM Dox + 5 µM Lap. In addition, the combinational therapy showed a decrease in the percentage of wound closure when compared to the control. Hence, the combinational therapy in which Lap suppresses the low-dose effect of Dox in SKBR3 cells may provide an effective intervention strategy for reducing the risk of metastasis in HER2-positive breast cancers.

Surface modification and endothelialization of biomaterials as potential scaffolds for vascular tissue engineering applications

This review highlights the recent developments of surface modification and endothelialization of biomaterials in vascular tissue engineering applications.