Properties of the amniotic membrane for potential use in tissue engineering

An important component of tissue engineering (TE) is the supporting matrix upon which cells and tissues grow, also known as the scaffold. Scaffolds must easily integrate with host tissue and provide an excellent environment for cell growth and differentiation. Most scaffold materials are naturally derived from mammalian tissues. The amniotic membrane (AM) is considered an important potential source for scaffolding material. The AM represents the innermost layer of the placenta and is composed of a single epithelial layer, a thick basement membrane and an avascular stroma. The special structure and biological viability of the AM allows it to be an ideal candidate for creating scaffolds used in TE. Epithelial cells derived from the AM have the advantages of stem cells, yet are a more suitable source of cells for TE than stem cells. The extracellular matrix components of the basement membrane of the AM create an almost native scaffold for cell seeding in TE. In addition, the AM has other biological properties important for TE, including anti-inflammatory, anti-microbial, anti-fibrosis, anti-scarring, as well as reasonable mechanical property and low immunogenicity. In this review, the various properties of the AM are discussed in light of their potential use for TE

The Antibacterial Effect of Low Temperature Stored Amnion on Growth of Escherichia Coli, Staphylococcus Aureus and Pseudomonas Aeruginosa

BACKGROUND AND OBJECTIVE: Amniotic membrane (AM) has a lot of applied properties like anti-bacterial characteristic mediated by peptides such as elafin. Because of limitations in use of freshly prepared tissue, there are various methods for long-term preservation of amniotic membrane. This study was conducted to determine the effect of cryopreservation, as one of the common methods of preservation of amniotic membrane, on its antibacterial property against the growth of commonly occurring bacteria in the clinic. METHODS: In this experimental study, the effect of fresh AM (from elective Cesarean) and cryopreserved (by 10% DMSO) AM on the growth of three standard bacterial strains including Escherichia coli ATCC 25922, Staphylococcus aureus, Pseudomonas aeruginosa and two clinical isolated strains of E.coli were evaluated using disk diffusion test. In this method, pieces of fresh or cryopreserved AM was placed in the culture plate after bacterial culturing. After incubation, the number of plates with inhibition zone and amount of inhibition zone were measured. The amount of elafin was measured in AM samples using ELISA. RESULTS: Fresh AM inhibit the growth of Pseudomonas aeruginosa and two clinical isolated strains of E.coli. However, it has no effect on the growth of standard strain of Escherichia coli and Staphylococcus aureus strain. There is no difference in the number of plates including inhibition zone between fresh and cryopreserved AM. The amount of elafin decreased significantly in cryopreserved AM (p<0.01). CONCLUSION: The results of this study showed that the anti-bacterial property of the AM depends on bacterial species. In addition, the cryopreservation process maintains anti-bacterial properties of amniotic stem cells

Feasibility investigation of direct laser cutting process of metal foam with high pore density

To avoid damage to the pore structure of metal foam, a laser cutting process for efficiently and directly cutting metal foam into regular shapes is proposed. After analyzing the proposed laser cutting process, its effects when applied to three different types of metal material (copper, ferroalloy, and nickel) and two levels of pore density, namely 90 and 110 pores per inch (PPI), were investigated. The results show that metal foam with a good surface quality can be obtained without damaging the pore structure by using the proposed laser cutting process. Of the three metal types considered, the highest material removal rate (MRR) and material oxidation rate (MOR) were observed for ferroalloy foam. Of the two pore densities, metal foam of 90 PPI showed a larger material removal rate than metal foam of 110 PPI. The MRR and MOR increased with an increase in the laser output power and decrease in the scanning speed. Using a central composite experimental design method, optimized processing parameters of 26 W laser output power and 475 mm/s scanning speed were adopted to cut the metal foam with a high pore density

The Effects of FGF8 and Shh on Expression of Dopaminergic Markers from Human Amniotic Epithelial Cells

Background and Objectives: Recently, interest has increased in the potential employment of embryonic stem cells for the treatment of Parkinson's disease, which has been considered as an alternative therapeutic strategy. Due to their pluripotent differentiation potential, the finding that they do not induce carcinoma and the fact that they do not raise the ethical concerns connected with human embryonic stem cells, human amniotic epithelial cells are considered to be a very promising cell source. The aim of this study was to investigate the effects of FGF8 and Shh on the expression of dopaminergic markers from human amniotic epithelial cells.Methods: In this study, we examined the differentiation of dopaminergic neurons in vitro from AECs using the expression of several markers including TH, DAT and DβH. For dopaminergic differentiation, sonic hedgehog (Shh) and FGF8 were added to cultures and the cultures were allowed to differentiate for 21 days. Analysis of AECs derived dopaminergic neurons was performed at the TH, DAT, β-tubulin III and DβH expression levels by immunocitochemistry. The significance of the data was tested by Student's t-test (between two groups) and one-way analysis of variance (ANOVA) followed by Tukey post-test. (p<0/01, p<0/05)Results: Combination of Shh and FGF8 showed the higher level of TH in comparison to control group or these factors alone. Moreover, Shh is more effective than FGF8 on DAT expression in comparison to expression of DβH.Conclusion: These results show the capability of AECs to express dopaminergic neural markers and this ability is affected by Shh and FGF8

Differentiation factors that influence neuronal markers expression in vitro from human amniotic epithelial cells

The differentiation of neural cells from embryonic stem cells is influenced by several growth factors. Amniotic epithelial cells (AECs) share many of the same characteristics as embryonic stem cells, and therefore those factors may similarly affect the derivation of neural cells from AECs. In this study, we examined the differentiation of neural cells in vitro from AECs following AECs treatment with retinoic acid (RA), basic fibroblast growth factor (bFGF) as well as investigation of bFGF withdrawal on neuronal differentiation. We also studied whether blocking bone morphogenetic protein (BMP) signaling using its antagonist, noggin, affects the derivation of neuronal cells from AECs. The effects of serum on the rate of neural markers expression were also examined. Analysis of AECs derived neurons was performed at some neural markers expression level by immunocytochemistry. All cultures treated with noggin showed the higher levels of neural markers expression than noggin free cultures. Combined treatment with bFGF and RA showed the highest level of neural markers in all treatment groups with or without noggin. bFGF withdrawal did not promote expression of neural markers, while its maintenance increased the expression of these markers. Serum-free condition decreased the viability of cells but increased the rate of neural markers expression. These results show the capability of AECs to express neural cell markers and this ability is affected by some factors including serum, noggin, bFGF and RA

Electrospun PGA/gelatin nanofibrous scaffolds and their potential application in vascular tissue engineering

Hadi Hajiali1, Shapour Shahgasempour1, M Reza Naimi-Jamal2, Habibullah Peirovi11Nanomedicine and Tissue Engineering Research Center, Shahid Beheshti University of Medical Sciences; 2Department of Chemistry, Iran University of Science and Technology, Tehran, IranBackground and methods: In this study, gelatin was blended with polyglycolic acid (PGA) at different ratios (0, 10, 30, and 50 wt%) and electrospun. The morphology and structure of the scaffolds were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and differential scanning calorimetry. The mechanical properties were also measured by the tensile test. Furthermore, for biocompatibility assessment, human umbilical vein endothelial cells and human umbilical artery smooth muscle cells were cultured on these scaffolds, and cell attachment and viability were evaluated.Results: PGA with 10 wt% gelatin enhanced the endothelial cells whilst PGA with 30 wt% gelatin increased smooth muscle cell adhesion, penetration, and viability compared with the other scaffold blends. Additionally, with the increase in gelatin content, the mechanical properties of the scaffolds were improved due to interaction between PGA and gelatin, as revealed by Fourier transform infrared spectroscopy and differential scanning calorimetry.Conclusion: Incorporation of gelatin improves the biological and mechanical properties of PGA, making promising scaffolds for vascular tissue engineering.Keywords: polyglycolic acid, gelatin, nanofiber, vascular tissue engineering, biocompatible scaffold&amp;nbsp

Differentiation factors that influence neuronal markers expression in vitro from human amniotic epithelial cells

The differentiation of neural cells from embryonic stem cells is influenced by several growth factors. Amniotic epithelial cells (AECs) share many of the same characteristics as embryonic stem cells, and therefore those factors may similarly affect the derivation of neural cells from AECs. In this study, we examined the differentiation of neural cells in vitro from AECs following AECs treatment with retinoic acid (RA), basic fibroblast growth factor (bFGF) as well as investigation of bFGF withdrawal on neuronal differentiation. We also studied whether blocking bone morphogenetic protein (BMP) signaling using its antagonist, noggin, affects the derivation of neuronal cells from AECs. The effects of serum on the rate of neural markers expression were also examined. Analysis of AECs derived neurons was performed at some neural markers expression level by immunocytochemistry. All cultures treated with noggin showed the higher levels of neural markers expression than noggin free cultures. Combined treatment with bFGF and RA showed the highest level of neural markers in all treatment groups with or without noggin. bFGF withdrawal did not promote expression of neural markers, while its maintenance increased the expression of these markers. Serum-free condition decreased the viability of cells but increased the rate of neural markers expression. These results show the capability of AECs to express neural cell markers and this ability is affected by some factors including serum, noggin, bFGF and RA

Surgical outcomes and local recurrence following total or subtotal gastrectomy for early adenocarcinoma of antrum

Objective: The choice between total gastrectomy (TG) and subtotal gastrectomy (STG) for early adenocarcinoma of the lower third of the stomach is still a matter of debate and controversy amongst surgeons. The aim of this study was to compare the surgical outcomes, quality of life (QoL), and local recurrence rates as well as other results of curative resection of early distal adenocarcinoma of the stomach using TG or STG performed in Iran. Methods: Hospital records of 66 patients with early distal adenocarcinoma of stomach that underwent even total or subtotal gastrectomy with perigastric (D2) lymphadenectomy between October 2001 and February 2006 in Taleghani Hospital, Iran were reviewed retrospectively. Demographic data as well as clinicopathological factors including number of involved lymph nodes, tumor grading, depth of invation, tumor size, and tumor type were recorded. Post-operative outcomes including mortality and morbidity, tumor recurrence and quality of life were assessed. Univariate analyses using Fisher's exact test, the Student t-test, and the Pearson x2 test were used. Results: Local recurrence of tumor was found in 8 (23) TG group patients and in 19 (61) patients of STG group, the Pearson x2 test showed a significant higher recurrence rate in STG (P value=0.002, Relative Risk=2.68, Confidence Interval: 1.37-5.24).The mean time interval between gastrectomy and tumor recurrence was not different between TG and STG. (19.75±5.1 vs. 18.0±7.8 respectively; P value=0.507) Tumor size &gt;5 cm (P value=0.004), diffuse type (P value=0.034), poor differentiation (P value=0.000) and serosal invasion (P value=0.012) were found to be significantly related to tumor recurrence in patients undergone gastrectomy. In none of the QoL measures a significant difference was found between TG and STG. Conclusion: Our results show that subtotal and total gastrectomy methods with perigastric lymphadenectomy have a similar postoperative complication rate and surgical outcomes as well as patient's QoL but STG was associated to a more than twofold increase in local recurrence risk

Induced in Vitro Differentiation of β-Tubulin III Expressed Cells from Human Amniotic Epithelial Cells

AbstractBackground and Objectives: The differentiation of neural cells from embryonic stem cells is influenced by several factors. Amniotic epithelial cells (AECs) share many of the same characteristics as embryonic stem cells, and therefore, those factors may similarly affect the derivation of neural cells from AECs. In this study, we examined the differentiation of neural cells in vitro from AECs using the expression of β-tubulin III marker, after AECs treatment with retinoic acid (RA), and the impact of basic fibroblast growth factor (bFGF). We also studied whether blocking bone morphogenetic protein (BMP) signaling the use of its antagonist, noggin, affects the derivation of neural cells from AECs.Methods: AECs were isolated from fresh human amniotic membrane and aggregated for 5 days in bacteriological dishes. The dissociated cells were transferred to adherent culture dishes and treated with noggin and bFGF for 7 days. In some cultures, bFGF was removed and RA was added and the cultures were allowed to differentiate for 21 days. Analysis of AECs derived neural cells was performed at the β-tubulin III expression levels by immunocitochemistry.Results: All cultures treated with noggin showed the higher levels of β-tubulin III expression than noggin free cultures. Combined treatment with bFGF and RA showed the highest level of β-tubulin III in all treatment groups with or without noggin. bFGF withdrawal did not promote expression of β-tubulin III, while its maintenance increased the expression of β-tubulin III.Conclusions: These results show the capability of AECs to express neural cell marker and this potential is affected by some factors including noggin, bFGF, RA.Keywords: Amnionc Epithelial Cells; Noggin Protein; bFGF; Tretinoin; β-tubulin III