Improving flow dynamics and storage longevity of a low-cost phosphorescent fingerprint powder.

An inexpensive, commercially available doped strontium aluminate phosphor with long-lived afterglow was prepared as a luminescent fingerprint dusting powder suited for challenging, highly patterned substrates; however, prolonged exposure to humidity was found to reduce that powder's affinity for fingermarks. Here, an enhanced preparation for synthesizing that fingerprint dusting powder is presented that prevents powder aggregation and loss of function upon exposure to humid environments. This was achieved by introducing a flow regulator during synthesis: hydrophobic silica SIPERNAT® D10 or SIPERNAT® D17. Increasing the hydrophobicity of the powder prevents aggregation by inhibiting the uptake of water, thereby improving the material's flow dynamics and transfer behavior from brush to fingermark. The angle of repose and flow characteristics made by the modified powders were quantified, with excellent affinity for fingermarks observed, even after being stored under 85% (±5%) humidity for 4 weeks. A preliminary comparison of the performance of the modified hydrophobic powders relative to the unmodified precursor revealed that more of the SIPERNAT® treated powder typically adhered to fingermarks while simultaneously imparting less background development. In addition, fewer clumps of particulate were observed in the developed fingermarks after addition of a hydrophobic flow regulator. This technical report outlines the updated method for synthesizing the fingerprint powder, with summarized flow performance results, and a demonstration of the modified powder's affinity for simulated fingermark evidence.

Chondroitin Sulfate as a Potential Modulator of the Stem Cell Niche in Cornea.

Chondroitin sulfate (CS) is an important component of the extracellular matrix in multiple biological tissues. In cornea, the CS glycosaminoglycan (GAG) exists in hybrid form, whereby some of the repeating disaccharides are dermatan sulfate (DS). These CS/DS GAGs in cornea, through their presence on the proteoglycans, decorin and biglycan, help control collagen fibrillogenesis and organization. CS also acts as a regulatory ligand for a spectrum of signaling molecules, including morphogens, cytokines, chemokines, and enzymes during corneal growth and development. There is a growing body of evidence that precise expression of CS or CS/DS with specific sulfation motifs helps define the local extracellular compartment that contributes to maintenance of the stem cell phenotype. Indeed, recent evidence shows that CS sulfation motifs recognized by antibodies 4C3, 7D4, and 3B3 identify stem cell populations and their niches, along with activated progenitor cells and transitional areas of tissue development in the fetal human elbow. Various sulfation motifs identified by some CS antibodies are also specifically located in the limbal region at the edge of the mature cornea, which is widely accepted to represent the corneal epithelial stem cell niche. Emerging data also implicate developmental changes in the distribution of CS during corneal morphogenesis. This article will reflect upon the potential roles of CS and CS/DS in maintenance of the stem cell niche in cornea, and will contemplate the possible involvement of CS in the generation of eye-like tissues from human iPS (induced pluripotent stem) cells.

KLF4 prevents epithelial to mesenchymal transition in human corneal epithelial cells via endogenous TGF-ß2 suppression.

INTRODUCTION: Krüppel-like factor 4 (KLF4) is considered one of the Yamanaka factors, and recently, we and others have shown that KLF4 is one of the transcription factors essential for reprogramming non-human corneal epithelial cells (HCECs) into HCECs. Since epithelial to mesenchymal transition (EMT) suppression is vital for homeostasis of HCECs via regulation of transcription factors, in this study, we aimed to investigate whether KLF4 prevents EMT in HCECs and to elucidate the underlying mechanism within the canonical TGF-ß signalling pathway, which is involved in corneal epithelial wound healing. METHODS: HCECs were collected from cadaver donors and cultivated. We generated KLF4-knockdown (KD) HCECs using siRNA transfection and analysed morphology, gene or protein expression, and endogenous TGF-ß secretion. KLF4 was overexpressed using lentiviral KLF4 expression vectors and underwent protein expression analyses after TGF-ß2 treatment. RESULTS: KLF4-KD HCECs showed a fibroblastic morphology, downregulation of the epithelial markers, keratin 12 and keratin 14, and upregulation of the mesenchymal markers, fibronectin 1, vimentin, N-cadherin, and SLUG. Although E-cadherin expression remained unchanged in KLF4-KD HCECs, immunocytochemical analysis showed that E-cadherin-positive adherens junctions decreased in KLF4-KD HCECs as well as the decreased total protein levels of E-cadherin analysed by immunoblotting. Moreover, within the TGF-ß canonical signalling pathway, TGF-ß2 secretion by HCECs increased up to 5 folds, and several TGF-ß-associated markers (TGFB1, TGFB2, TGFBR1, and TGFBR2) were significantly upregulated up to 6 folds in the KLF4-KD HCECs. SMAD2/3, the main signal transduction molecules of the TGF-ß signalling pathway, were found to be localised in the nucleus of KLF4-KD HCECs. When KLF4 was overexpressed, cultivated HCECs showed upregulation of epithelial markers, keratin 14 and E-cadherin, indicating the contributory role of KLF4 in the homeostasis of human corneal epithelium in vivo. In addition, KLF4 overexpression in HCECs resulted in decreased SMAD2 phosphorylation and altered nuclear localisation of SMAD2/3, even after TGF-ß2 treatment. CONCLUSIONS: These results show that KLF4 prevents EMT in HCECs and suggest a novel role of KLF4 as an endogenous TGF-ß2 suppressor in the human corneal epithelium, thus highlighting the potential of KLF4 to prevent EMT and subsequent corneal fibrotic scar formation by attenuating TGF-ß signalling.

Quantification of clonal heterogeneity of mesenchymal progenitor cells in dental pulp and bone marrow.

This study aimed to compare the expression of "classical" stem cell markers, the proliferative capacity and differentiation ability of clonal mesenchymal stem cell (MSC) populations isolated from animal matched dental pulp (DP) and bone marrow (BM) of rats. MSCs were derived from the aforementioned tissues, with immature MSCs selected for by preferential fibronectin-adherence and resultant single-cell derived clonal populations culture expanded. Colony forming efficiencies were 12 times greater for DP clones compared with BM clones. Expansion of isolated colonies, however, was 5 times more successful for BM clones. All clones exceeded 40 population doublings (PDs) and all exhibited periods of high and low proliferative rates. PDs were approximately 1.5 times higher for BM clones. All BM clones readily differentiated towards osteoblasts, chondrocytes and adipocytes. Of the three DP clones analysed, all demonstrated osteogenesis, albeit with reduced efficiency compared to BM clones. One clone demonstrated adipogenesis and one clone chodrogenesis. qPCR determined quantifiable differences in Msx2, Vcam2 and Mcam with no clone showing similarity to another. The expression of a specific mesenchymal marker did not predict proliferative or differentiation potential. These results also suggest lineage restriction of the DP clones.