Dynamics of Monolayer Growth in Vapor–Liquid–Solid GaAs Nanowires Based on Surface Energy Minimization

The vapor–liquid–solid growth of III-V nanowires proceeds via the mononuclear regime, where only one island nucleates in each nanowire monolayer. The expansion of the monolayer is governed by the surface energetics depending on the monolayer size. Here, we study theoretically the role of surface energy in determining the monolayer morphology at a given coverage. The optimal monolayer configuration is obtained by minimizing the surface energy at different coverages for a set of energetic constants relevant for GaAs nanowires. In contrast to what has been assumed so far in the growth modeling of III-V nanowires, we find that the monolayer expansion may not be a continuous process. Rather, some portions of the already formed monolayer may dissolve on one of its sides, with simultaneous growth proceeding on the other side. These results are important for fundamental understanding of vapor–liquid–solid growth at the atomic level and have potential impacts on the statistics within the nanowire ensembles, crystal phase, and doping properties of III-V nanowires.

Isolation and Differentiation of Amniotic Membrane Stem Cells Into Keratinocytes

The human amniotic membrane is a highly abundant and readily available tissue that may be useful for regenerative medicine and cell therapy. The amniotic membrane stem cells can differentiate into multiple cell lineages; they have low immunogenicity and anti-inflammatory functions. This research aims to examine the protocols for the isolation of human amniotic membrane stem cells, including their phenotypic characterization and in vitro potential for differentiation toward keratinocytes. Human placentas were obtained from selected cesarean-sectioned births. We isolated amniotic stem cells by trypsin and collagenase B digestion and centrifuged with Percoll. After monolayer expansion of adherent cells, the cells were characterized by immunocytology with octamer-binding transcription factor 4 and differentiated into keratinocytes by treating the cells with insulin, hydrocortisone, BMP-4, and vitamin C. Protocol for isolation of stem cells from amniotic membrane has high efficiency. Differentiation markers of stem cells into keratinocytes, such as vimentin, cytokeratin (CK) 14, and CK19, were determined by reverse transcription-polymerase chain reaction increase over time in culture. Stem cells isolated from the amniotic membrane can differentiate into keratinocytes. It has opened the prospect of using stem cells to regenerate skin and clinical applications.

Intra-hydrogel culture prevents transformation of mesenchymal stem cells induced by monolayer expansion

Intra-hydrogel culture can mitigate the cellular transformation of MSCs induced by expansion through the regulation of proteoglycans in cancer (PGC) and pathways in cancer (PC) focal adhesion (FA) and the MAPK signaling pathway.

THE EFFECTS OF PALMVITEE ON HUMAN NASAL SEPTAL CHONDROCYTES CULTURE EXPANSION AND CARTILAGE RECONSTRUCTION

Palmvitee may act as a beneficial supplement to cartilage tissue engineering which is currently still has certain limitation on chondrocyte expansion and dedifferentiation. Our objectives in thisstudy were to evaluate the effects of Palmvitee on the growth kinetic and phenotype gene expression of human nasal septal chondrocytesin monolayer expansion as well as cartilage reconstruction via tissue engineering technology. Human chondrocytes were cultured inmediums containing various Palmvitee concentrations. Among the different test groups, the medium containing Palmvitee at 3 μg/ml supported the highest chondrocyte growth rate. The gene expression in monolayer chondrocytes culture supplemented with 3 μg/ml Palmviteedemonstrated similar results as in control. Cultured chondrocytes from the medium added with 3 μg/ml Palmvitee were then mixed with Pluronic F127 for cartilage reconstruction in nude mice model. Palmvitee supplementation supported the engineered cartilage development as shown in the histological and gene expression analysis on engineered tissue after 8 weeks of implantation. Therefore, Palmvitee at 3 μg/ml is beneficial for the human nasal septal chondrocytes monolayer expansion and cartilage engineering.

Effect of Fibroblast Growth Factor 2 on Equine Synovial Fluid Chondroprogenitor Expansion and Chondrogenesis

Mesenchymal stem cells have been identified in the synovial fluid of several species. This study was conducted to characterize chondroprogenitor (CP) cells in equine synovial fluid (SF) and to determine the effect of fibroblast growth factor 2 (FGF-2) on SF-CP monolayer proliferation and subsequent chondrogenesis. We hypothesized that FGF-2 would stimulate SF-CP proliferation and postexpansion chondrogenesis. SF aspirates were collected from adult equine joints. Colony-forming unit (CFU) assays were performed during primary cultures. At first passage, SF-cells were seeded at low density, with or without FGF-2. Following monolayer expansion and serial immunophenotyping, cells were transferred to chondrogenic pellet cultures. Pellets were analyzed for chondrogenic mRNA expression and cartilage matrix secretion. There was a mean of 59.2 CFU/mL of SF. FGF-2 increased the number of population doublings during two monolayer passages and halved the population doubling times. FGF-2 did not alter the immunophenotype of SF-CPs during monolayer expansion, nor did FGF-2 compromise chondrogenesis. Hypertrophic phenotypic markers were not expressed in control or FGF-2 groups. FGF-2 did prevent the development of a “fibroblastic” cell layer around pellet periphery. FGF-2 significantly accelerates in vitro SF-CP expansion, the major hurdle to clinical application of this cell population, without detrimentally affecting subsequent chondrogenic capacity.