Hypoxia/Reoxygenation (H/R) cardiac injury is of great importance in understanding Myocardial Infarctions, which affect a major part of the working population causing debilitating side effects and often-premature mortality. H/R injury primarily consists of apoptotic and necrotic death of cardiomyocytes due to a compromise in the integrity of the mitochondrial membrane. Major factors associated in the deregulation of the membrane include fluctuating reactive oxygen species (ROS), deregulation of mitochondrial permeability transport pore (MPTP), uncontrolled calcium (Ca2+) fluxes, and abnormal caspase-3 activity. Erythropoietin (EPO) is strongly inferred to be cardioprotective and acts by inhibiting the above-mentioned processes. Surprisingly, the underlying mechanism of EPO's action and H/R injury is yet to be fully investigated and elucidated. This study examined whether EPO maintains Ca2+ homeostasis and the mitochondrial membrane potential (ΔΨm) in cardiomyocytes when subjected to H/R injury and further explored the underlying mechanisms involved. H9C2 cells were exposed to different concentrations of EPO post-H/R, and 20 U/ml EPO was found to significantly increase cell viability by inhibiting the intracellular production of ROS and caspase-3 activity. The protective effect of EPO was abolished when H/R-induced H9C2 cells were treated with Wortmannin, an inhibitor of Akt, suggesting the mechanism of action through the activation Akt, a major survival pathway.

Available online xxxKeywords: Articular cartilage Sodium alginate Chondrogenesis Extra-cellular matrix (ECM) Differentiation a b s t r a c t Aim: Alternate strategies to regenerate the damaged tissue require exogenous supply of several chondrocyte implants. There are inherent challenges to optimize an appropriate tissue culture methodology that can aid in enrichment of chondrocytes. The aim of the study was to explore the differentiation potential, expansion and growth kinetics of the human adipose derived stem cells (hADSCs) in alginate microspheres in comparison to chondrogenesis from the cartilage tissue.Methods: Isolated hADSCs and cartilage derived chondrocytes were cultured and characterized. The distribution of stem cells within alginate bead was imaged by scanning electron microscopy (SEM). Encapsulated hADSCs were monitored for their cell viability, cell proliferation and apoptosis via JC-1 staining, MTT assay and Annexin V assays respectively.The alginate cell constructs were analyzed for chondrogenic gene expression by RT-PCR.Results: The chondrocyte pellet culture from cartilage demonstrated lower growth potential as compared to alginate encapsulation. hADSCs were successfully encapsulated within alginate matrix with >80% cell viability. Apoptotic assays provided safety profile for the alginate during cell growth. The up-regulation of cartilage specific genes like TGF-b, collagen type-X, COMP was observed during the entire period of culture. Conclusion:The chondrogenesis in pellet culture from cartilage tissue conserved the chondrocyte phenotype better with rich GAG polysaccharides. However, owing to an enriched chondrocyte requirement, alginate as a scaffold design would aid in the treatment of large focal defects.

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