Human embryonic stem cell (hESC) lines are traditionally derived and maintained on mouse embryonic fibroblasts (MEF) which are xenogeneic and enter senescence rapidly. In view of the clinical implications of hESCs, the use of human fibroblast as feeders has been suggested as a plausible alternative. However, use of fibroblast cells from varying sources leads to culture variations along with the need to add FGF2 in cultures to sustain ES cell pluripotency. In this study we report the derivation of FGF2 expressing germ layer derived fibroblast cells (GLDF) from hESC lines. These feeders could support the pluripotency, karyotypes and proliferation of hESCs with or without FGF2 in prolonged cultures as efficiently as that on MEF. GLDF cells were derived from embryoid bodies and characterized for expression of fibroblast markers by RT-PCR, Immunofluorescence and by flow cytometry for CD marker expression. The expression and secretion of FGF2 was confirmed by RT-PCR, Western blot, and ELISA. The hESC lines cultured on MEF and GLDF were analyzed for various stemness markers. These feeder cells with fibroblast cells like properties maintained the properties of hESCs in prolonged culture over 30 passages. Proliferation and pluripotency of hESCs on GLDF was comparable to that on mouse feeders. Further we discovered that these GLDF cells could secrete FGF2 and maintained pluripotency of hESC cultures even in the absence of supplemental FGF2. To our knowledge, this is the first study reporting a novel hESC culture system which does not warrant FGF2 supplementation, thereby reducing the cost of hESC cultures.

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Small file processing in Hadoop is one of the challenging task. The performance of the Hadoop is quite good when dealing with large files, because they require lesser meta data and consume less memory. But while dealing with enormous amount of small files, meta data grows linearly and Name Node memory got overloaded hence overall performance of the Hadoop degrades. This paper presents a dual merge technique HB-EHA (Hash Based-Extended Hadoop Archive) that will resolve the small file issue of Hadoop and provide an excellent solution for massive small files that are generated in the health care management applications. The proposed technique merges the small files using two level compaction, therefore size of meta data at name node get reduced and less memory will be used. The indexing will be carried out over the archives and files can be accessed after merging in real time. Index files in the proposed approach can read partially that improves the name node memory usage and also offers the file appending capability in the existing archive. The proposed technique first creates Hadoop archive from the small files and then uses two special hash functions i.e. SSHF (Scalable-Splittable Hash Function) and HT-MMPHF (Hollow Trie Monotone Minimal Perfect Hash Function), SSHF is used to dynamically distribute the archives meta-data to the associated slave index files, and these slave index files will be further written to the final index files, the order of the meta-data in final index file will be preserved by the HT-MMPHF. The evaluation outcome exhibit that proposed technique is 13% & 17% faster than HDFS with caching enabled and disabled respectively, and 38% & 47% faster than the HAR with caching and without caching respectively. While comparing with map file, proposed technique is 28 & 35 time faster with caching and without caching respectively. HB-EHA is maximum 40% & 28% faster than the HBAF with and without caching respectively.

Embryonic stem cells are considered the mother of all kinds of tissues and cells and it is envisioned as the holy grail of regenerative medicine. However, their use in cell replacement therapies (CRT) has so far been limited and their potentials are yet to be fully realized. The use of human embryonic stem cells (hESC) involves many safety issues pertaining to culture conditions and epigenetic changes. The role and importance of an epigenomic signature in derivation and maintenance of hESC are discussed. We provide a list of important epigenetic markers, which should be studied for evaluation of safety in hESC-based cell replacement therapies. These genes also need to be screened to determine an epigenetic signature for pluripotency in the hESCs. Finally a comprehensive list of all known stemness signature genes and the marker genes for different germ line lineages are presented. This review aims at summing up most of the intriguing molecules that can play a role in the maintenance of pluripotency and can help in determining hESC differentiation to various lineages. Extensive understanding of these markers will eventually help the researchers to transform the hESC research from bench to the bedside. The use of hESCs in CRTs is still in its infancy; much effort is warranted to turn them into the much dreamed about magic wand of regenerative medicine.

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