| dc.description.abstract | Cardio-mimetic hydrogel-based biomaterials are inevitable in bioengineering cardiac
tissue. The research focused to engineer and evaluate biologically favorable and cardiac
compatible hydrogel scaffolds using the natural polysaccharides such as alginate, starch
and carboxy methyl cellulose reinforced with synthetic polymers PVA and PEG for
cardiac tissue engineering (CTE). Two panel of hydrogel scaffolds viz ACPV and ASPG
were synthesized. ACPV hybrid hydrogel system was prepared by interpenetrating
alginate and cellulose with the synthetic polymer PVA and the subsets ACPV1 and
ACPV2 were prepared by varying the composition of the co-polymers. Similarly, PEG
was used in ASPG system instead of PVA and the two subsets ASPG1 and ASPG2 were
prepared by altering the constituent ratio of co-polymers. Divalent cation, Ca2+ was used
as the crosslinking agent in both the preparations.
ATR-IR analysis, water profiling, surface morphometry studies, contact angle
and tensile strength measurements and biostability studies evaluated the physicochemical
and mechanical properties of the hydrogels. The findings showed that all the hydrogels
exhibited appreciable properties with respect to the presence of surface functional groups,
optimum pore architecture and water holding capacity. The hydrogels were amphiphilic
and biodegradable with appreciable mechanical properties.
Cell material interaction was determined by direct contact assay, MTT assay and
by evaluating the extent of cell adsorption and penetration onto hydrogel surfaces, using
H9c2 cells. Direct contact assay demonstrated that the cells did not show any deviation
from the normal morphology suggesting the biocompatibility of the hydrogels.
Cytotoxicity studies of H9c2 cells cultured with hydrogel extract revealed viability of
>80% in all subsets. Both ACPV and ASPG hydrogels displayed superior adhesion and
spreading of H9c2 cells. Both ACPV and ASPG hydrogel systems promoted plasma
protein adsorption on their interstices where the major fraction of adsorbed protein was
contributed by albumin.
The hydrogel surfaces were functionalized for antioxidant and antimicrobial
activity by loading them with ascorbic acid and antibiotics viz, amikacin and vancomycin
respectively. The antibiotic loaded ACPV and ASPG hydrogel subsets displayed
significantly increased zone of inhibition against Gram-positive and Gram-negative
bacteria. ACPV and ASPG hydrogels loaded with ascorbic acid displayed appreciable
antioxidant response in vitro cell free system as evident from DPPH and nitric oxide
scavenging assay. Interestingly, the hydrogels showed inherent antioxidant potential as
they demonstrated significantly decreased level of oxidative stress in RAW267.4 cells
upon direct contact with ACPV and ASPG hydrogels.
Immunocompatibility of ACPV and ASPG hydrogels were evaluated by studying
the expression of inflammatory mediators such as IL6, NF-Kβ, IL-10, TGF-β, TNF-α
and IKβ using RAW 264.7 cells. The activation of RAW cells upon contact with the
hydrogels were minimal suggesting the immunocompatibility. Immunofluorescence
revealed that ACPV hydrogels exhibited immunomodulatory effects when compared
with ASPG system based on the expression status of IL6, NF-Kβ, IL-10, TGF-β, TNF-α
and IKβ. The genes and regenerative pathways involving these genes were assessed by
NetworkAnalyst program. The study concluded that the selected genes were intimately
associated with 370 genes and 120 pathways related to inflammation and/or
immunomodulation revealing their potential network. | en_US |
