Three-dimensional wet electrospun scaffold system for the differentiation of adipose-derived mesenchymal stem cells to islet-like clusters.

Stem cell-derived islet-like clusters (ILCs) are an alternative source of pancreatic beta cells for the treatment of diabetic mellitus. An ideal 3D culture platform for the generation of ILCs of desired cluster size is a challenge due to the clustering of islet cells in the 2D culture systems. The islet cells cultured in 2D conditions produce clusters of large size, which are less efficient in terms of insulin secretion and viability. In this study, we report that ILCs formed on a PCL-based wet electrospun fibrous scaffold with larger pore size produced clusters of the desired size, compared to that cultured on a conventional electrospun sheet. The collagen functionalization on this wet electrospun polycaprolactone (PCL) scaffold showed enhanced insulin secretion and cell viability compared to the non-functionalized or conventionally electrospun PCL scaffold. The collagen-coated wet electrospun 3D scaffold produced ILCs of cluster diameter 70 ± 20 µm and the conventionally electrospun PCL sheet produced larger ILC clusters of diameter 300 ± 10 µm. Hence the results indicate the collagen-functionalized wet electrospun scaffold system could be a potential scaffold for islet tissue engineering.

Growth and Regeneration of Osteochondral Cells in Bioactive Niche: A Promising Approach for Osteochondral Tissue Repair.

Functional repair of osteochondral defects caused due to osteoarthritis still remains the greatest challenge in orthopedic therapy. A prospective clinical strategy would be exploring osteochondral tissue engineering possibilities that promote simultaneous regeneration of the articular cartilage layer as well as the underlying subchondral bone. Incorporating the appropriate cues onto the scaffolds for the regeneration of the two contrasting tissues is therefore a demanding function. In the present study, a polymer-ceramic composite scaffolding material consisting of ternary bioactive glass (67.12 SiO2/28.5 CaO/4.38 P2O5 mol %) incorporated into a semi interpenetrating polymer network of hydrophilic-hydrophobic polymer (poly(vinyl alcohol)-polycaprolactone) matrix is prepared and physicochemically characterized. In vitro bioactivity, bone-bonding ability, and biocompatibility evaluation were performed in comparison with the pristine scaffold. The degree of chondrogenic and osteogenic potential of mesenchymal stem cells in both the scaffolds was evaluated by gene expression studies. Although both the scaffolds favored the differentiation to both cell lineages in their respective medium, a higher expression of bone specific genes found with the composite scaffold suggested that this composite scaffold would serve better for osteal layer and henceforth to promote the integration of the osteochondral construct at the defect site.

Assessing the 3D Printability of an Elastomeric Poly(caprolactone-co-lactide) Copolymer as a Potential Material for 3D Printing Tracheal Scaffolds.

The advent of 3D printing technology has made remarkable progress in the field of tissue engineering. Yet, it has been challenging to reproduce the desired mechanical properties of certain tissues by 3D printing. This was majorly due to the lack of 3D printable materials possessing mechanical properties similar to the native tissue. In this study, we have synthesized four different ratios of poly(caprolactone-co-lactide (PLCL) and tested their 3D printing capabilities. The physicochemical properties of the material were characterized using Fourier-transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). Furthermore, the mechanical properties were assessed using the universal testing machine (UTM). The ratio with the higher lactide content was found to have better printability. Out of the different ratios assessed, a suitable ratio having the desired mechanical properties and printability was identified and 3D printed into a tracheal scaffold. Thus, PLCL can be a potential material for 3D printing of tissues like the trachea.

Dual crosslinked pullulan-gelatin cryogel scaffold for chondrocyte-mediated cartilage repair: synthesis, characterization andin vitroevaluation.

Cryogels, a subset of hydrogels, have recently drawn attention for cartilage tissue engineering due to its inherent microporous architecture and good mechanical properties. In this study a dual crosslinked pullulan-gelatin cryogel (PDAG) scaffold was synthesized by crosslinking gelatin with oxidized pullulan by Schiff's base reaction followed by cryogelation. Chondrocytes seeded within the PDAG scaffolds and cultured for 21 din vitrodemonstrated enhanced cell proliferation, enhanced production of cartilage-specific extracellular matrix and up-regulated sulfated glycosaminoglycan without altering the articular chondrocyte phenotype. Quantitative reverse transcription-polymerase chain reaction-based gene expression studies, immunofluorescence, and histological studies demonstrated that the PDAG scaffold significantly enhanced the expression of chondrogenic marker genes such as type II collagen, aggrecan, and SOX9. Taken together, these results demonstrated that PDAG scaffold prepared by sequential Schiff's base reaction and cryogelation would be a promising cell-responsive scaffold for cartilage tissue engineering applications.

Long-Term Evaluation of Allogenic Chondrocyte-Loaded PVA-PCL IPN Scaffolds for Articular Cartilage Repair in Rabbits.

OBJECTIVE: This study tested the long-term efficacy of two synthetic scaffolds for osteochondral defects and compare the outcomes with that of an established technique that uses monolayer cultured chondrocytes in a rabbit model. METHODS: Articular cartilage defect was created in both knees of 18 rabbits and divided into three groups of six in each. The defects in first group receiving cells loaded on Scaffold A (polyvinyl alcohol-polycaprolactone semi-interpenetrating polymer network (Monophasic, PVA-PCL semi-IPN), the second on Scaffold B (biphasic, PVA-PCL incorporated with bioglass as the lower layer), and the third group received chondrocytes alone. One animal from each group was sacrificed at 2 months and the rest at 1 year. O'Driscoll's score measured the quality of cartilage repair. RESULTS: The histological outcome had good scores (22, 20, and 19) for all three groups at 2 months. At 1-year follow-up, the chondrocyte alone group had the best scores (mean 20.0 ± 1.4), while the group treated by PVA-PCL semi-IPN scaffolds fared better (mean 15 ± 4.2) than the group that received biphasic scaffolds (mean 11.8 ± 5.9). In all three groups, defects treated without cells scored less than the transplant. CONCLUSION: These results indicate that while these scaffolds with chondrocytes perform well initially, their late outcome is disappointing. We propose that for all scaffold-based tissue repairs, a long-term evaluation should be mandatory. The slow degrading scaffolds need further modifications to improve the milieu for long-term growth of chondrocytes and their hyaline phenotype for the better incorporation of tissue-engineered constructs.

3D-printed biphasic scaffolds for the simultaneous regeneration of osteochondral tissues.

Osteochondral tissue engineering (OCTE) involves the simulation of highly complex tissues with disparate biomechanical properties. OCTE is regarded as the best option for treating osteochondral defects, most of the drawbacks of current treatment methodologies can be addressed by this method. In recent years, the conventional scaffolds used in cartilage and bone regeneration are gradually being replaced by 3D printed scaffolds (3DP). In the present study, we devised the strategy of 3D printing for fabricating biphasic and integrated scaffolds that are loaded with bioactive factors for enhancing the osteochondral tissue regeneration. Polycaprolactone (PCL) and poly(lactic-co-glycolic acid) (PLGA), is used along with bioactive factors (chondroitin sulphate and beta-tricalcium phosphate (ßTCP)) for the upper cartilage and lower bone layer respectively. The 3D printed bi-layered scaffolds with varying infill density, to mimic the native tissue, are not previously explored for OCTE. Hence, we tested the simultaneous osteochondrogenic differentiation inducing potential of the aforesaid 3D printed biphasic scaffoldsin vitro, using rabbit adipose derived mesenchymal stem cells (ADMSCs). Further, the biphasic scaffolds were highly cytocompatible, with excellent cell adhesion properties and cellular morphology. Most importantly, these biphasic scaffolds directed the simultaneous differentiation of a single stem cell population in to two cell lineages (simultaneous differentiation of rabbit ADMSCs into chondrocytes and osteoblasts). Further, these scaffolds enhanced the production of ECM and induced robust expression of marker genes that is specific for respective cartilage and bone layers. The 3D printed OCTE scaffold of our study hence can simulate the native osteochondral unit and could be potential futuristic biomimetic scaffold for osteochondral defects. Furtherin vivostudies are warranted.

Chemokine SDF1 Mediated Bone Regeneration Using Biodegradable Poly(D,L-lactide-co-glycolide) 3D Scaffolds and Bone Marrow-Derived Mesenchymal Stem Cells: Implication for the Development of an "Off-the-Shelf" Pharmacologically Active Construct.

There is an increasing need for bone substitutes for reconstructive orthopedic surgery following removal of bone tumors. Despite the advances in bone regeneration, the use of autologous mesenchymal stem cells (MSC) presents a significant challenge, particularly for the treatment of large bone defects in cancer patients. This study aims at developing new chemokine-based technology to generate biodegradable scaffolds that bind pharmacologically active proteins for regeneration/repair of target injured tissues in patients. Primary MSC were cultured from the uninvolved bone marrow (BM) of cancer patients and further characterized for "stemness". Their ability to differentiate into an osteogenic lineage was studied in 2D cultures as well as on 3D macroporous PLGA scaffolds incorporated with biomacromolecules bFGF and homing factor chemokine stromal-cell derived factor-1 (SDF1). MSC from the uninvolved BM of cancer patients exhibited properties similar to that reported for MSC from BM of healthy individuals. Macroporous PLGA discs were prepared and characterized for pore size, architecture, functional groups, thermostability, and cytocompatibility by ESEM, FTIR, DSC, and CCK-8 dye proliferation assay, respectively. It was observed that the MSC+PLGA+bFGF+SDF1 construct cultured for 14 days supported significant cell growth, osteo-lineage differentiation with increased osteocalcin expression, alkaline phosphatase secretion, calcium mineralization, bone volume, and soluble IL6 compared to unseeded PLGA and PLGA+MSC, as analyzed by confocal microscopy, biochemistry, ESEM, microCT imaging, flow cytometry, and EDS. Thus, chemotactic biomacromolecule SDF1-guided tissue repair/regeneration ability of MSC from cancer patients opens up the avenues for development of "off-the-shelf" pharmacologically active construct for optimal repair of the target injured tissue in postsurgery cancer patients, bone defects, damaged bladder tissue, and radiation-induced skin/mucosal lesions.

Keratinocytes-hair follicle bulge stem cells-fibroblasts co-cultures on a tri-layer skin equivalent derived from gelatin/PEG methacrylate nanofibers.

Generation of full thickness skin equivalent models is of increasing interest in tissue engineering because of the limitations inherent to current models. In recent years, considerable interest has been given to electrospun hybrid nanofibers prepared using natural and synthetic combinations of polymers. By blending two polymers, gelatin and PEG methacrylate we created a novel functional hydrogel-named GelMet. By adjusting the concentration of GelMet between 14 and 20wt%, three types of electrospun membranes were fabricated. Keratinocytes, hair follicle bulge stem cells (HFBSCs) and fibroblasts were successfully isolated and cultured in 14 wt%, 17 wt% and 20 wt% GelMet scaffolds respectively and generated a tri-layered electrospun construct. Characterization of GelMet electrospun membranes were compared with those of the pure gelatin nanofibers. Due to plasticity, by incorporating HFBSCs, it is expected to increase the cell content of skin substitute without the need to incorporate several different cell populations. The fiber diameter and pore size of the scaffold for each layer were fabricated in such a way to mimic the structural gradation of collagen matrix across the native skin. Good mechanical properties and dimensional stability of GelMet scaffold, combined with the ability to support cell growth in vitro, suggest its tremendous potential application in skin tissue engineering.

A nonadherent chitosan-polyvinyl alcohol absorbent wound dressing prepared via controlled freeze-dry technology.

In modern-day 21st century, the demand has increased for absorbent dressings that are nonadherent and maintain structural integrity without shedding lint in the wound site. This study looks at the development of a blend of polysaccharide chitosan and polyvinyl alcohol (PVA) and its fabrication using a novel controlled freeze-drying process, thus giving it channeled pores. The dressing was assessed for in vitro physical properties such as fluid handling, mechanical integrity, bioadhesion, and blood clotting. Additionally, cytocompatibility and hemocompatibility tests were conducted. An in vitro wound-healing assay was performed to determine the healing response. Furthermore, toxicological safety evaluation tests such as acute systemic toxicity, skin irritation, and sensitization were conducted. The results revealed that the developed dressing was biocompatible with a good absorbency rate of 0.63 ± 0.13 g/cm2, enhanced mechanical integrity, and low bioadhesive strength with good healing characteristics and nontoxic nature, which indicated that it was an ideal nonadherent absorbent wound dressing.

Tissue-engineered islet-like cell clusters generated from adipose tissue-derived stem cells on three-dimensional electrospun scaffolds can reverse diabetes in an experimental rat model and the role of porosity of scaffolds on cluster differentiation.

In the current study, three-dimensional (3D) nanofibrous scaffolds with pore sizes in the range of 24-250 µm and 24-190 µm were fabricated via a two-step electrospinning method to overcome the limitation of obtaining three-dimensionality with large pore sizes for islet culture using conventional electrospinning. The scaffolds supported the growth and differentiation of adipose-derived mesenchymal stem cells to islet-like clusters (ILCs). The pore size of the scaffolds was found to influence the cluster size, viability and insulin release of the differentiated islets. Hence, islet clusters of the desired size could be developed for transplantation to overcome the loss of bigger islets due to hypoxia which adversely impacts the outcome of transplantation. The tissue-engineered constructs with ILC diameter of 50 µm reduced glycemic value within 3-4 weeks after implantation in the omental pouch of diabetic rats. Detection of insulin in the serum of implanted rats demonstrates that the tissue-engineered construct is efficient to control hyperglycemia. Our findings prove that the 3D architecture and pore size of scaffolds regulates the morphology and size of islets during differentiation which is critical in the survival and function of ILCs in vitro and in vivo.

Continental outflow of anthropogenic aerosols over Arabian Sea and Indian Ocean during wintertime: ICARB-2018 campaign.

Chemical characterisation of atmospheric aerosols over Arabian Sea (AS) and Indian Ocean (IO) have been carried out during the winter period (January to February 2018) as part of the Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB-2018). Mass concentrations of organic carbon (OC), elemental carbon (EC), water soluble and insoluble OC (WSOC, WIOC), primary and secondary OC (POC, SOC), water-soluble inorganic ions and trace metals have been estimated with a view to identify and quantify the major anthropogenic pollutants affecting the oceanic environments. Aerosol mass loading was found to exhibit strong spatial heterogeneity (varying from 13 to 84 µg m-3), significantly modulated by the origin of air-mass trajectories. Chemical analysis of aerosols revealed the presence of an intense pollution plume over south-eastern coastal Arabian Sea, near to south-west Indian peninsula (extending from ~ 12°N to 0° at 75°E) with a strong latitudinal gradient (~3 µg m-3/deg. from north to south) dominated by anthropogenic species contributing as high as 73% (38% nss-SO42-, 24.2% carbonaceous aerosols (21% Organic Matter, 3.2% EC) and 10% NH4+). Anthropogenic signature over oceanic environment was also evident from the dominance and high enrichment of elements like Zn, Cu, Mn and Pb in trace metals. Long-range transport of air-masses originating from Indo Gangetic Plains and its outflow regions in Bay of Bengal, has been seen over Arabian Sea during winter, that imparted such strong anthropogenic signatures over this oceanic environment. Comparison with previous cruise studies conducted nearly two decades ago shows a more than two-fold increase in the concentration of nss-SO42-, over the continental outflow region in Arabian Sea.

Glutamic acid-based dendritic peptides for scaffold-free cartilage tissue engineering.

Current treatment modalities for cartilage regeneration often result in the production of fibrous-type cartilage tissue at the defect site, which has inferior mechanical properties as compared to native hyaline cartilage. Further, effective treatments are not available at present, for preventing age-related as well as disease-related hypertrophic development of chondrocytes. In the present study, we designed and synthesized three sets of glutamic acid-based dendritic peptides, differing in degree of lipidation as well as branching. Each set constitutes of N-terminal protected as well as corresponding N-deprotected peptides. Altogether, six peptides [BE12, E12, BE3(12)4, E3(12)4, BE3OMe, E3OMe] were tested for their chondrogenesis enhancing potential in vitro, using rabbit adipose derived mesenchymal stem cells (ADMSCs). Immunohistochemical and gene expression studies as well as biochemical analyses revealed that the lipopeptides [E12 and BE3(12)4] are able to enhance chondrogenic differentiation of ADMSCs significantly (p < 0.001) as compared to control group (chondrogenic medium alone). Glycosaminoglycan content, and the chondrogenic marker genes like Aggrecan (Acan), Type II collagen (Col2a1), Hyaluronan synthase 2 (Has2), and SRY-box 9 (Sox9) expressions were found to be significantly increased in E12 and BE3(12)4 treated groups. Most importantly, the BE3(12)4 treated group showed significantly lower Type I collagen (Col1a2) and Type X collagen (Col10a1) transcript levels (p < 0.001), indicating its potential for hyaline cartilage formation and also to prevent hypertrophic development. Thus, the lipopeptides E12 and BE3(12)4 may be useful for preventing chondrocyte hypertrophy and realizing the hyaline nature of regenerated cartilage tissue in tissue engineering. STATEMENT OF SIGNIFICANCE: The current treatment modalities for degenerative cartilage diseases are unsatisfactory as the resultant regenerated cartilage is often fibrous in nature with inferior mechanical properties. Further, there is no proper treatment available for age-related development of chondrocyte hypertrophy at present. In this study we synthesized glutamic acid-based lipopeptides, which differ in the degree of lipidation as well as branching. We used a combinatorial approach of scaffold-free tissue engineering and dendritic lipopeptides to achieve hyaline-like cartilage tissue from adipose derived mesenchymal stem cells in vitro. Gene expression analysis revealed the down regulation of fibrous cartilage marker Col1a2 and hypertrophic marker Col10a1, suggesting that these lipopeptides may be useful for achieving mechanically superior hyaline cartilage regeneration in future.

Surface ozone in the Doon Valley of the Himalayan foothills during spring.

Elevated ozone (O3) pollution is observed every spring over the Northern Indian region including the Himalayan foothills, with a maximum typically in the month of May. However, studies investigating influences of photochemistry and dynamics in the valleys of Central Himalaya are limited. Here, in situ surface O3 observations conducted at Dehradun (77.99° E, 30.27° N, 600 m above mean sea level) in the Doon Valley during April-July 2018 are presented. These O3 observations reveal the prevalence of an urban environment over Dehradun with enhanced levels during noontime (66.4 ppbv ± 11.0 ppbv in May) and lower levels during night (26.7 ppbv ± 11.5 ppbv). Morning time O3 enhancement rate at Dehradun (7.5 ppbv h-1) is found to be comparable to that at Bode (7.3 ppbv h-1) in another valley of Himalayan foothills (Kathmandu), indicating stronger anthropogenic emissions in the Doon Valley as well. Daily average O3 at Dehradun varied in the range of 13.7-71.3 ppbv with hourly values reaching up to 103.1 ppbv during the study period. Besides the in situ photochemical O3 production, the entrainment of O3-rich air through boundary layer dynamics also contributes in noontime O3 enhancement in the Doon Valley. Monthly average O3 at Dehradun (49.3 ppbv ± 19.9 ppbv) is observed to be significantly higher than that over urban sites in Northern India (35-41 ppbv) and Bode (38.5 ppbv) in the Kathmandu Valley during May. O3 photochemical buildup, estimated to be 30.3 ppbv and 39.7 ppbv during April and May, respectively, is significantly lower in June (21.2 ppbv). Copernicus Atmosphere Monitoring Service (CAMS) model simulations successfully reproduce the observed variability in noontime O3 at Dehradun (r = 0.86); however, absolute O3 levels were typically overestimated. The positive relationship between CAMS O3 and CO (r = 0.65) together with an O3/CO slope of 0.16 is attributed to the influences of biomass burning besides anthropogenic emissions on observed O3 variations in the Doon Valley. O3 observations show an enhancement by 35-56% at Dehradun during a high-fire activity period in May 2018 as compared to a low-fire activity period over the Northern Indian region in agreement with the enhancement found in CAMS O3 fields (10-65%) over the region in the vicinity of Dehradun.

Seasonal changes in carbonaceous aerosols over a tropical coastal location in response to meteorological processes.

Near-surface atmospheric aerosols (PM10) collected from a tropical coastal location in south-west peninsular Indian region for a duration of 6 years (2012-18) (N = 461) were analysed for carbonaceous aerosol components, the less studied aerosol species. Organic carbon (OC), its water soluble-insoluble (WSOC and WIOC) components, primary-secondary (POC and SOC) fractions and elemental carbon (EC) were examined for understanding the annual, seasonal, day-night variations in abundance pattern along with associated physical and meteorological processes. Total carbonaceous aerosols accounting for 36% of the collected aerosol mass with 31.5% organic matter (OM) and 4.5% EC respectively, exhibited consistent seasonal pattern throughout the study period with high concentration during winter followed by post-monsoon, pre-monsoon and monsoon. Delineation of marine and continental components of carbonaceous species based on their relative dominance during different air-mass periods, shows that while marine aerosols were a combination of natural sources comprising of volatile, semi-volatile species and secondary organics (from marine VOC precursors); the continental aerosols were composed of anthropogenic combustion sources (fossil fuel, biomass emissions etc). Based on the measurements of OC and EC during 2005-09 and 2012-18, their long term trends (for more than a decade) were investigated. Although OC showed an increasing tendency, EC exhibited a decrease with the total carbonaceous aerosols exhibiting a gradual decreasing trend over the years, indicating that they do not strictly reverberate the reported increasing trend observed over north-central parts of India. This can be presumed to be due to the reduced anthropogenic inputs over the location owing to the control measures and policies. The strong convective activity and large scale monsoon phenomena also helps in the effective dispersion of pollutants. Making use of comprehensive measurement of carbonaceous aerosols and the previous measurements of other aerosol components, an improved chemical composition model is presented.

Strontium functionalized scaffold for bone tissue engineering.

Drug functionalized scaffolds are currently being employed to improve local delivery of osteoprotective drugs with the aim of reducing their loading dose as well as unwanted systemic complications. In this study we tested a poly-(ε) caprolactone (PCL)-laponite-strontium ranelate (SRA) composite scaffold (PLS3) for its abilities to support growth and osteogenic differentiation of human marrow derived stromal stem cells (hMSC). The in vitro experiments showed the PLS3 scaffold supported cell growth and osteogenic differentiation. The in vivo implantation of hMSC seeded PLS3 scaffold in immunocompromised mice revealed vascularized ectopic bone formation. PLS3 scaffolds can be useful in bone regenerative applications in the fields of orthopaedics and dentistry.

Diurnal and seasonal variations in surface methane at a tropical coastal station: Role of mesoscale meteorology.

In view of the large uncertainties in the methane (CH4) emission estimates and the large spatial gaps in its measurements, studies on near-surface CH4 on regional basis become highly relevant. This paper presents the first time observational results of a study on the impacts of mesoscale meteorology on the temporal variations of near-surface CH4 at a tropical coastal station, in India. It is based on the in-situ measurements conducted during January 2014 to August 2016, using an on-line CH4 analyzer working on the principle of gas chromatography. The diurnal variation shows a daytime low (1898-1925ppbv) and nighttime high (1936-2022ppbv) extending till early morning hours. These changes are closely associated with the mesoscale circulations, namely Sea Breeze (SB) and Land Breeze (LB), as obtained through the meteorological observations, WRF simulations of the circulations and the diurnal variation of boundary layer height as observed by the Microwave Radiometer Profiler. The diurnal enhancement always coincides with the onset of LB. Several cases of different onset timings of LB were examined and results presented. The CH4 mixing ratio also exhibits significant seasonal patterns being maximum in winter and minimum in pre-monsoon/monsoon with significant inter-annual variations, which is also reflected in diurnal patterns, and are associated with changing synoptic meteorology. This paper also presents an analysis of in-situ measured near-surface CH4, column averaged and upper tropospheric CH4 retrieved by Atmospheric Infrared Sounder (AIRS) onboard Earth Observing System (EOS)/Aqua which gives insight into the vertical distribution of the CH4 over the location. An attempt is also made to estimate the instantaneous radiative forcing for the measured CH4 mixing ratio.

Decadal changes in surface ozone at the tropical station Thiruvananthapuram (8.542° N, 76.858° E), India: effects of anthropogenic activities and meteorological variability.

This paper presents the first observational results from an Indian station on the long-term changes in surface ozone (O3)-a major environmental pollutant and green house gas-over a period of about 40 years. It is based on the in situ measurements carried out during 1973-1975, 1983-1985, 1997-1998 and 2004-2014 at the tropical coastal station, Thiruvananthapuram. From 1973 to 1997, surface O3 shows a slow increase of ~ 0.1 ppb year-1 and a faster increase of 0.4 ppb year-1 afterwards till 2009 after which it showed a levelling off till 2012 followed by a minor decrease. The highest rate of increase is observed during 2005 to 2009 (2 ppb year-1), and the overall increase from 1973 to 2012 is ~ 10 ppb. The increase in day time O3 (peak O3) is estimated as 0.42 ppb year-1 during 1997-2012 and 2.93 ppb year-1 during 2006-2012. Interestingly, the long-term trend in O3 showed seasonal dependence which is more pronounced during O3 peaking seasons (winter/summer). The observed trends were analysed in the light of the changes in NO2, a major outcome of anthropogenic activities and methane which has both natural and anthropogenic sources and also meteorological parameters. Surface O3 and NO x exhibited positive association, but with varying rate of increase of O3 for NO x < 4 and > 4 ppb. Methane, a precursor of O3 also showed increase in tune with O3. Unlike many other high-latitude locations, meteorology plays a significant role in the long-term trends in O3 at this tropical site with water vapour abundance and strong solar irradiance which favour photochemistry. A comparison with the corresponding changes in the satellite-retrieved tropospheric column O3 (TCO) also showed an increase of 0.03 DU year-1 during 1996-2005 which enhanced to 0.12 DU year-1 after 2005. Both surface O3 and satellite-retrieved TCO were positively correlated with daily maximum temperature, increasing at the rate of 1.54 ppb °C-1 and 1.9 DU °C-1, respectively, on yearly basis. Surface O3 is found to be negatively correlated with water vapour content (ρv) at this tropical site, but at higher levels of ρv, O3 shows a positive trend.

Bioactive nano-fibrous scaffold for vascularized craniofacial bone regeneration.

There has been a growing demand for bone grafts for correction of bone defects in complicated fractures or tumours in the craniofacial region. Soft flexible membrane like material that could be inserted into defect by less invasive approaches; promote osteoconductivity and act as a barrier to soft tissue in growth while promoting bone formation is an attractive option for this region. Electrospinning has recently emerged as one of the most promising techniques for fabrication of extracellular matrix such as nano-fibrous scaffolds that can serve as a template for bone formation. To overcome the limitation of cell penetration of electrospun scaffolds and improve on its osteoconductive nature, in this study, we fabricated a novel electrospun composite scaffold of polyvinyl alcohol (PVA)-poly (ε) caprolactone (PCL)-Hydroxyapatite based bioceramic (HAB), namely, PVA-PCL-HAB. The scaffold prepared by dual electrospinning of PVA and PCL with HAB overcomes reduced cell attachment associated with hydrophobic PCL by combination with a hydrophilic PVA and the HAB can contribute to enhance osteoconductivity. We characterized the physicochemical and biocompatibility properties of the new scaffold material. Our results indicate PVA-PCL-HAB scaffolds support attachment and growth of stromal stem cells; [human bone marrow skeletal (mesenchymal) stem cells and dental pulp stem cells]. In addition, the scaffold supported in vitro osteogenic differentiation and in vivo vascularized bone formation. Thus, PVA-PCL-HAB scaffold is a suitable potential material for therapeutic bone regeneration in dentistry and orthopaedics.

Evaluating KIND1 human embryonic stem cell-derived pancreatic progenitors to ameliorate streptozotocin-induced diabetes in mice.

BACKGROUND & OBJECTIVES: Diabetes is a global disease burden. Various stem cell types are being explored to serve as an alternative source of islets. This study was conducted to evaluate the ability of in-house developed human embryonic stem (hES) cells-derived pancreatic progenitors to ameliorate diabetic symptoms in mice. METHODS: Pancreatic progenitors were packed in macro-capsules and transplanted into six male Swiss mice and four mice were taken as controls. Thirty days post-transplantation, diabetes was induced by streptozotocin treatment. Mice were then followed up for >100 days and body weight and blood glucose levels were regularly monitored. RESULTS: Control mice lost weight, maintained high glucose levels and did not survive beyond 40 days, whereas transplanted group maintained body weight and four of the six mice had lowered blood glucose levels. About five-fold increase was observed in human C-peptide levels in the recipients of progenitor transplants as compared to diabetic control. INTERPRETATION & CONCLUSIONS: The beneficial effect of transplanted cells was not long-lasting. Further studies are required to critically evaluate and compare the potential of endogenous pluripotent stem cells and hES cells-derived progenitors before moving from bench to the bedside.