Naveen Kumar Mekala

Influence of dilute acid and alkali pretreatment on reducing sugar production from corncobs by crude enzymatic method: a comparative study.

In the present study, two commonly used catalysts in chemical pretreatment, sulfuric acid and sodium hydroxide, were tested to evaluate the effect of solid-to-liquid ratio on pretreatment and enzymatic hydrolysis. Solid to liquid ratio (S/L) was influential on sugars released with an increase in the S/L ratio between 0.03 and 0.2. Enzymatic digestibility of 0.25 M H2SO4 pretreated corncobs were released more sugars (415.12 mg/mL); whereas, corncobs pretreated with NaOH released 350.12 mg/mL of reducing sugars at S/L 0.05. Further, in comparison with NaOH pretreated corncobs, acid treated material substantially increased the accessibility and digestibility of cellulose during crude enzymatic hydrolysis (28.96 FPU) and released 398.95 mg/mL reducing sugars.

Enhanced Proliferation and Osteogenic Differentiation of Human Umbilical Cord Blood Stem Cells by L-Ascorbic Acid, In Vitro

The multilineage potentiality of cord blood stem cells has been experimentally proven in a number of cell based therapies. Umbilical cord blood (UCB) derived mesenchymal stem cells (MSCs), on prolonged exposure with Lascorbic acid have been successfully differentiated in to osteoblasts (bone forming cells) without altering the phenotype of the cells. In this case study, the role of L-ascorbic acid on collagen biosynthesis and mineral deposition in MSCs has been assessed, which are ultimately matured in to an insoluble extra cellular matrix (ECM), giving mechanical strength to the bone cells. Moreover, up to specific concentration of L-ascorbic acid (250μM), proliferation as well as differentiation potential of the cells remains unaltered. Further increase in concentrations of L-ascorbic acid (500 μM) reduced the cell proliferation and subsequently leads to morphological changes in the cultures. This may be due to an immature antioxidant defense system, which can be overcome by treating the cell cultures with antioxidants. Our final results conclude that Lascorbic acid has positive effect on the ostogenic differentiation of cord blood stem cells, and the concentration of ascorbic acid is vital in cell proliferation and differentiation.

Physical and degradation properties of PLGA scaffolds fabricated by salt fusion technique

Tissue engineering scaffolds require a controlled pore size and interconnected pore structures to support the host tissue growth. In the present study, three dimensional (3D) hybrid scaffolds of poly lactic acid (PLA) and poly glycolic acid (PGA) were fabricated using solvent casting/particulate leaching. In this case, partially fused NaCl particles were used as porogen (200-300µ) to improve the overall porosity (≥90%) and internal texture of scaffolds. Differential scanning calorimeter (DSC) analysis of these porous scaffolds revealed a gradual reduction in glass transition temperature (Tg) (from 48°C to 42.5°C) with increase in hydrophilic PGA content. The potential applications of these scaffolds as implants were further tested for their biocompatibility and biodegradability in four simulated body fluid (SBF) types in vitro. Whereas, simulated body fluid (SBF) Type1 with the optimal amount of HCO3− ions was found to be more appropriate and sensible for testing the bioactivity of scaffolds. Among three combinations of polymer scaffolds, sample B with a ratio of 75:25 of PLA: PGA showed greater stability in body fluids (pH 7.2) with an optimum degradation rate (9% to 12% approx). X-ray diffractogram also confirmed a thin layer of hydroxyapatite deposition over sample B with all SBF types in vitro.

Role of Signaling Pathways in Mesenchymal Stem Cell Differentiation

Mesenchymal Stem Cells (MSCs) are self-renewing cells with ability to differentiate into organized, functional network of cells. In recent past research in developing clinical applications for MSCs has increased significantly. MSCs exhibit multi potential proliferation, and are capable of differentiating into cartilage, bone, neuronal cells and adipocytes, etc. Signaling pathways, transcription factors and growth factors modulate the differentiation of MSCs into different cell lineages. Besides, physical factors may regulate the molecular differentiation of stem cells. The main theme of this paper is to review the signaling pathways related to bone morphogenetic proteins (BMPs), epidermal growth factors (EGF), transforming growth factors (TGF), wingless type MMTV integration site (wnt) proteins, fibroblastic growth factor (FGF), and transcriptional regulating factors significance in the MSCs differentiation.

Osteoblast differentiation of umbilical cord blood-derived mesenchymal stem cells and enhanced cell adhesion by fibronectin

Mononuclear cells isolated from human umbilical cord blood were differentiated in to spindle shaped fibrous mesenchymal stem cells (MSCs) in DMEM with 10% fetal bovine serum. These progenitor cells were further examined for their ability to differentiate into osteoblasts by culturing them in osteogenic differentiation media (Stem Pro®). Calcium mineralization assay, alizarin red S, von kossa staining confirmed that MSCs from cord blood were capable of mineralization when they were cultured in osteogenic medium. The adhesion studies shown that MSCs have greater affinity towards fibronectin (FN) coated dishes, compared to albumin (Alb) coated dishes due to CD29and CD44 surface receptors.

Current bioenergy researches: strengths and future challenges

Abstract Bioenergy is major stake holder in meeting global future energy needs. This contribution can be extended significantly in the near future, by reducing the greenhouse gas emission and saving environment, as well as improving trade balances, contributing to energy security, providing opportunities for socioeconomical development in rural areas. Bioenergy could sustainably offer a quarter and a third of global primary energy supply by 2050. Bioenergy is the only renewable source that can replace fossil fuels in all energy markets in the production of heat, electricity, and fuels for transport. Many bioenergy principles can be used to convert biomass feedstock into final bioenergy products. The technologies for producing heat and power from feedstock are already well defined and fully commercialized. A wide variety of conversion technologies are under construction, with improved competence, lower costs and improved environmental protection. However, the possible competition between raw materials for bioenergy with other biomass applications must be carefully answered. The output of biomass feedstock and food grains needs to be increased by good agricultural practices. Logistics and infrastructure issues should be spoken off, and there is need for further scientific innovations leading to more competent and cleaner conversion of more assorted feedstock.

Combination of ERG9 Repression and Enzyme Fusion Technology for Improved Production of Amorphadiene in Saccharomyces cerevisiae

The yeast strain (Saccharomyces cerevisiae) MTCC 3157 was selected for combinatorial biosynthesis of plant sesquiterpene amorpha-4,11-diene. Our main objective was to overproduce amorpha 4-11-diene, which is a key precursor molecule of artemisinin (antimalarial drug) produced naturally in plant Artemisia annua through mevalonate pathway. Farnesyl diphosphate (FPP) is a common intermediate metabolite of a variety of compounds in the mevalonate pathway of yeast and leads to the production of ergosterols, dolichol and ubiquinone, and so forth. In our studies, FPP converted to amorphadiene (AD) by expressing heterologous amorphadiene synthase (ADS) in yeast. First, ERG9 (squalane synthase) promoter of yeast was replaced with repressible methionine (MET3) promoter by using bipartite gene fusion method. Further to overcome the loss of the intermediate FPP through competitive pathways in yeast, fusion protein technology was adopted and farnesyldiphosphate synthase (FPPS) of yeast has been coupled with amorphadiene synthase (ADS) of plant origin (Artemisia annua L.) where amorphadiene production was improved by 2-fold (11.2 mg/L) and 4-fold (25.02 mg/L) in yeast strains YCF-002 and YCF-005 compared with control strain YCF-AD (5.5 mg/L), respectively.

Study on Osteoblast like Behavior of Umbilical Cord Blood Cells on Various Combinations of PLGA Scaffolds Prepared by Salt Fusion

The osteogenic potential of mesenchymal stem cells (MSCs) from umbilical cord blood (UCB) on porous poly lactide-co-glycolide (PLGA) scaffolds have been reported to differentially support osteogenic differentiation based on polymer composition (80:20, 75:25 and 70:30 percent of PLA: PGA, respectively). Along with polymer composition; fused NaCl crystal matrix prior to solvent casting improves the porosity and pore interconnectivity in 3D scaffolds, which has significant impact on cell proliferation. FTIR and XRD studies of PLGA scaffolds also verified the intermolecular interactions, phase distribution and crystallinity in scaffolds. Among three scaffold combinations, sample B (75:25) has showed maximum porosity with optimum water uptake/retention abilities. Impact of polymer composition and porosity on cell proliferation was investigated through MTT assay, where sample B was observed to be supporting better cell proliferation,due to its internal structure. The above results were further confirmed by ALP and Col-I gene expression studies using RT-PCR. Immuno fluorescent studies also revealed the extracellular filamentous actin organization over the scaffolds, where cell adhesion and proliferation was found to be higher with increase in PGA content, which is a hydrophilic polymer.

Development of Petri Net-Based Dynamic Model for Improved Production of Farnesyl Pyrophosphate by Integrating Mevalonate and Methylerythritol Phosphate Pathways in Yeast

In this case study, we designed a farnesyl pyrophosphate (FPP) biosynthetic network using hybrid functional Petri net with extension (HFPNe) which is derived from traditional Petri net theory and allows easy modeling with graphical approach of various types of entities in the networks together. Our main objective is to improve the production of FPP in yeast, which is further converted to amorphadiene (AD), a precursor of artemisinin (antimalarial drug). Natively, mevalonate (MEV) pathway is present in yeast. Methyl erythritol phosphate pathways (MEP) are present only in higher plant plastids and eubacteria, but not present in yeast. IPP and DAMP are common isomeric intermediate in these two pathways, which immediately yields FPP. By integrating these two pathways in yeast, we augmented the FPP synthesis approximately two folds higher (431.16 U/pt) than in MEV pathway alone (259.91 U/pt) by using HFPNe technique. Further enhanced FPP levels converted to AD by amorphadiene synthase gene yielding 436.5 U/pt of AD which approximately two folds higher compared to the AD (258.5 U/pt) synthesized by MEV pathway exclusively. Simulation and validation processes performed using these models are reliable with identified biological information and data.

Significance of Biotic Factors in Mesenchymal Stem Cell Fate in Regenerative Medicine

Stem and progenitor cell research is a complex and exciting field which promises curative discoveries in numerous areas including cancer, diabetes, and regenerative medicine. Use of biotic factors or growth factors has played an essential role in the development of stem cell research. These biologically active components have been administered into stem cells either to improve or maintain the stem cell proliferation, or to encourage controlled differentiation into more defined cell types. Small molecules such as 6-Bromoindirubin-3´-oxime (BIO), cardiogenol-C, etc can help stem cell research by controlling or influencing the regulatory changes in a controlled manner and to help understand the mechanisms during stem cell differentiation. Extra cellular matrix (ECM) is another significant biotic factor, which mediates cell and tissue behavior by influencing cell-matrix interactions. Thus, in this review we would like to emphasize significance of various growth factors in stem cell research.