Quantitative reduction of methyl tetrazolium by fresh vein homograft biopsies in vitro is an index of viability

Antitumor effect and apoptosis induction of Alocasia cucullata (Lour.) G. Don in human gastric cancer cells in vitro and in vivo

Background

Alocasia cucullata (Lour.) G. Don was applied in traditional Chinese medicine for the treatment of cancer in Chinese Southwest area. Its antitumor effect was scrutinized in vitro and in vivo. And for the first time, the mechanism of extract of A. cucullata (EAC) against human gastric cancer cell was well examined.

Methods

To detect the most effective fraction, the antiproliferation efficacy of four fractions (namely derivatives by adding EAC to n-BuOH, petroleum ether, EtOAc and water until dissolve fully) against five cancer cell lines were screened by MTT assay. Among four fractions, the IC50s of n-BuOH fraction of EAC (EAC-B) against the five cell lines and time-dependent inhibition to gastric cancer cell line (MGC-803) were further investigated (MTT assay). In vivo antitumor efficacy of EAC-B was examined by MGC-803 bearing tumor nude mice. Especially, the paper focused on the relevant mechanism study of EAC-B against MGC-803 included cell cycle distribution (flow cytometry) and cyclin D1 expression (RT-PCR and western blot), apoptosis (Hoechst 33342 stain and flow cytometry), apoptosis-related protein expression (Akt, p-Akt, ERK, p-ERK, Bcl-2, Bax) by western blot, and caspase3/7 activity assay.

Results

EAC-B showed its cytotoxicity against various tumor cell lines, particularly against gastric cancer cells with IC50 value of 18.8 μg/mL in vitro. Tumor weight was significantly reduced by EAC-B in vivo. In the mechanism study, EAC-B increased cell ratio at G0/G1 phase and reduced cyclin D1 expression both at protein and mRNA level on MGC-803. Chromatin condensation and apoptosis were also observed. EAC-B down-regulated p-Akt, p-ERK expression and up-regulated Bax/Bcl-2 ratio. Further, caspase 3/7 activation was enhanced as well.

Conclusions

This study demonstrated that EAC-B had potent antitumor activity both in vitro and in vivo. Its mechanism is primarily via antiproliferation of G0/G1 arrest and cell pro-apoptosis, including PI-3 K/Akt pathway, ERK activity, stimulated cytochrome C release and caspase 3/7 activity accompanied with an increase of Bax/Bcl-2 ratio. EAC-B may be a potential source of novel compounds for gastric cancer treatment.

Neuroprotective effects of puerarin against beta-amyloid-induced neurotoxicity in PC12 cells via a PI3K-dependent signaling pathway

Epidemiological data have indicated that estrogen replacement therapy (ERT) can decrease the risk of developing Alzheimer's disease (AD). Phytoestrogens have been proposed as potential alternatives to ERT. The aim of the present study was to assess the neuroprotective effects of puerarin, a phytoestrogen isolated from Pueraria lobata, against the toxicity of beta-amyloid (Aβ) in relation to the mitochondria-mediated cell death process, and to elucidate the role the activation of Akt and modulation of the pro- and antiapoptotic proteins in puerarin-induced neuroprotection. The present study shows that puerarin afforded protection against Aβ-induced toxicity through inhibiting apoptosis in PC12 cells. This result was also confirmed by the activated caspase-3 assay. P-Akt, Bcl-2 and p-Bad expression increased after pretreatment with puerarin in PC12 cells exposed to Aβ(25-35), whereas Bax expression and cytochrome c release decreased. Interestingly, these effects of puerarin against Aβ(25-35) insult were abolished by wortmannin, an inhibitor of PI3K phosphorylation. These findings suggest that puerarin prevent Aβ-induced neurotoxicity through inhibiting neuronal apoptosis, and might be a potential preventive or therapeutic agent for AD.

Detrimental effects of mechanical stretch on smooth muscle function in saphenous veins

OBJECTIVE

This study evaluated the smooth muscle functional response and viability of human saphenous vein (HSV) grafts after harvest and explored the effect of mechanical stretch on contractile responses of porcine saphenous vein (PSV).

METHODS

The contractile responses (stress, 10(5) N/m(2)) of deidentified, remnant HSV grafts to depolarizing potassium chloride and the agonist norepinephrine were measured in a muscle organ bath. Cellular viability was evaluated using a methyl thiazole tetrazolium (MTT) assay. A PSV model was used to evaluate the effect of radial, longitudinal, and angular stretch on smooth muscle contractile responses.

RESULTS

Contractile responses varied greatly in HSV harvested for autologous vascular and coronary bypass procedures (0.04198 ± 0.008128 × 10(5) N/m(2) to 0.1192 ± 0.02776 × 10(5) N/m(2)). Contractility of the HSV correlated with the cellular viability of the grafts. In the PSV model, manual radial distension of ≥ 300 mm Hg had no impact on the smooth muscle responses of PSV to potassium chloride. Longitudinal and angular stretch significantly decreased the contractile function of PSV by 33.16% and 15.26%, respectively (P < .03).

CONCLUSIONS

There is considerable variability in HSV harvested for use as an autologous conduit. Longitudinal and angular stretching during surgical harvest impairs contractile responsiveness of the smooth muscle in saphenous vein. Avoiding stretch-induced injuries to the conduits during harvest and preparation for implantation may reduce adverse biologic responses in the graft (eg, intimal hyperplasia) and improve patency of autologous vein graft bypasses.

Maintained geometry, elasticity and contractility of human saphenous vein segments stored in a complex tissue culture medium

OBJECTIVE

Improved maintenance of endothelial function and higher viability of saphenous vein grafts stored in a complex tissue culture medium (TCM) have been demonstrated. This article studies the biomechanical properties of saphenous vein segments.

DESIGN

Biomechanical properties of 72 saphenous vein segments remaining from coronary bypass grafting of 32 patients have been studied after different storage procedures.

MATERIALS

The materials studied included fresh segments, segments stored in a cooled conventional physiological salt solution (normal Krebs-Ringer (nKR)) for 1-2 weeks, segments stored in a cooled chemically defined TCM (X-Vivo) for 1,2,3 and 4 weeks and segments cryopreserved for a few weeks.

METHODS

Specimens were cannulated at both ends and pressure-diameter curves were recorded in the 0-85-mmHg range in nKR with 10 microM norepinephrine added to induce maximum smooth muscle contraction, as well as in Ca(2+)-free medium to induce full relaxation. Tensile strength was checked at 300 mmHg. Distensibility, elastic modulus and active strain were computed.

RESULTS

Segments stored in nKR dilated morphologically, their distensibility decreased and they lost their ability to contract (1.5+/-0.7% from 10.1+/-1.5% of control) in 1 week. The TCM-stored segments preserved their contractility until 1 week, and this parameter only slowly decreased afterwards (first week, 11.5+/-7.3%; fourth week, 3.9+/-0.6%). There was a slight decrease in wall thickness but the lumen diameter was not affected. The elastic parameters of these segments were practically identical to those of fresh segments. Cryopreserved segments narrowed morphologically, their wall thickened and contractility diminished.

CONCLUSIONS

Storage in TCM helps preserve the passive and active biomechanical properties of human saphenous vein segments. Such properties can be expected to improve graft tissue viability.

Evaluation of the biological responses of osteoblast-like UMR-106 cells to the engineered porous PHBV matrix

Poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) has been investigated for biomedical applications due to its many biologically favorable properties. However, to explore its application in bone tissue engineering, the poorly bioactive surface property of PHBV must be improved. To engineer PHBV to achieve a biologically active surface, in this study each porous PHBV matrix was prepared by solute leaching of salt/PHBV cast film and was treated with ozone followed by dip coating with type I collagen. The biological responses of osteoblast-like UMR-106 cells after being grown on the engineered PHBV matrix were evaluated. Confocal microscopy and the MTT assay were used to map and quantify the viable cell proliferation on the PHBV matrix, respectively. The cells were cultivated in osteogenic media containing beta-glycerophosphate and later stained with alizarin red to visualize mineralization of the matrix. RNA was extracted from the UMR-106 cells, and reverse transcriptase-polymerase chain reaction (RT-PCR) was applied to detect expression of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) (a house keeping gene) and bone sialoprotein (BSP) (marker of the osteoblastic phenotype). The results showed that the UMR-106 cells after cultivation on the engineered PHBV matrix retained the osteoblastic phenotype characteristics, indicating that the porous PHBV matrix after ozone treatment and collagen dip coatings are a promising scaffold for bone tissue engineering applications.