There is an intense interest in developing innovative biomaterials which support the invasion and proliferation of living cells for potential applications in tissue engineering and regenerative medicine. Present study demonstrated the in vivo biocompatibility and toxicity of a macromolecules cross-linked biocomposite scaffold composed of hydroxyapatite, alginate, chitosan and fucoidan abbreviated as HACF. The in vivo biocompatibility and toxicity of HACF scaffold were tested by comparing them with those of a biocompatible surgical metal implant (SMI) in a subcutaneous rat model. Following the implantation, animals were sacrificed and the scaffolds were resected at 1st, 4th, and 8th weeks; the surrounding tissue along with the implant was removed to evaluate its biocompatibility. The effects of implanted biomaterial scaffolds on vital organ systems such as liver, kidney, etc., have been studied by hematology and serum biochemistry. The activities of pro-inflammatory marker enzymes such as COX, 5-LOX, 15-LOX, and NOS were normal in rats implanted with HACF scaffold. Hematological parameters, antioxidant and lipid peroxidation status were also found to be normal in implanted rats same as that of control and SMI. The modulatory effect of implanted scaffold over inflammatory and stress signaling cascades were confirmed by the normalized mRNA expressions of NF-κB, TNF-α and IL-6. The histopathological analysis of liver, kidney and tissue support our results. Taken together, these results demonstrated that HACF biocomposite scaffold signifies its suitability for further research as a scaffold material for cartilage tissue engineering applications.
Marine biopolymer composite materials provide a technological platform for launching biomedical applications. Biomaterials demand good biocompatibility without the possibility of inflammation or foreign body reactions. In this study, we prepared two biocomposite hydrogels namely; HAC (hydroxyapatite, alginate & chitosan) and HACF (hydroxyapatite, alginate, chitosan & fucoidan) followed by calcium chloride cross linking. The prepared scaffolds were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. Porosity measurement, swelling, biodegradation, hemolysis, RBC aggregation, plasma protein adsorption and cytotoxicity studies were also done. The hydrogel scaffold HACF possessed a well-defined porous architecture, sufficient water holding capacity, better hemocompatibility and biodegradability. The biocompatibility was confirmed through in vitro cytotoxicity studies such as MTT assay, Neutral red uptake, DAPI staining, Trypan blue dye exclusion test and direct contact assay in L929 mouse fibroblast cells. In addition, immunomodulatory and anti-inflammatory properties of both of these scaffolds were revealed by the mRNA expressions of major inflammatory marker genes in cytotoxic condition such as TNF-α, IL-6 and NF-κB. The physiochemical characterization and biological responses of HACF hydrogel signifies its suitability for various tissue engineering applications.
<p>Even though anti thrombotic effects have been reported with polysaccharides isolated from various marine algae of dictyotaceae, containing uronic acid as the main constituent. But a new polysaccharide was isolated from a species of marine algae from the Kerala coast with a composition different from those reported so far. The antiplatelet and antithrombotic activities of polysaccharides from <em>Padina tetrastromatica</em> were investigated on platelet aggregation in vitro and on pulmonary thrombosis in vivo. The polysaccharide fractions showed concentration dependent inhibitory effects on ADP-induced platelet aggregation. Using an <em>in vivo </em>mouse thrombotic model in which mice were challenged with an intravenous injection of collagen and epinephrine mixture, oral administration of the polysaccharide prior to the injection produced a significant inhibition of thrombotic death or paralysis. Aspirin showed a significant inhibition of thrombotic death similar to polysaccharide of higher dose. Polysaccharide fractions showed significant prolongation of mouse tail bleeding time. The present findings showed clear evidence of protection against thromboembolism and had good antithrombotic activity. Available data obtained by in vitro models suggest that there is a correlation between the sulfate content and antithrombotic activity.</p>
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