Search

Calcium (Ca2+) signaling is one of the earliest factors to coordinate plant adaptive responses. As direct sensors and activators of Ca2+ signals, calcium-dependent protein kinases (CDPKs) were reported to be widely involved in regulating different biotic and abiotic stress stimuli. In this study, 32 Hevea brasiliensis CDPK (HbCDPK) genes were predicted and classified into four subgroups. Among them, the full-length coding sequences of 28 HbCDPK genes were confirmed by RT-PCR and verified by sequencing. Putative cis-elements assay in the promoters of HbCDPKs showed that most of the HbCDPK genes contained gibberellic acid-responsive element (GARE), abscisic acid-responsive element (ABRE), salicylic acid-responsive element (SARE), defense and stress responsive element (TC-rich repeats) and low-temperature response element (LTR), which could be activated by different biotic and abiotic stresses. Real-time PCR analysis indicated that 28 HbCDPK genes respond to infection of pathogenic fungi and a variety of phytohormones. Subcellular localization was observed with most HbCDPKs located in cell membrane, cytoplasm or organelles. Some HbCDPKs were confirmed to cause reactive oxygen species (ROS) production and accumulation in rubber tree mesophyll protoplast directly. HbCDPK 5 was strongly induced by the inoculation with Colletotrichum gloeosporioides and was chosen for further analysis. HbCDPK5 localized to the cell membrane and cytoplasm, and obviously regulated the accumulation of ROS in rubber tree mesophyll protoplast. Overexpression of HbCDPK5 in Arabidopsis enhanced the resistance to Botrytis cinerea. These results indicate that rubber tree CDPK genes play important roles in plant disease resistance. [ABSTRACT FROM AUTHOR]

Abstract: To improve the biocompatibility of three dimensional (3D) poly(d,l-lactic acid) (PDLLA), surface modification with baicalin was performed via a physical entrapment method in this study. The tissue reactions and bone conductivities of such modified PDLLA scaffolds were histologically assessed by using a rabbit radialis defect model in vivo. The native PDLLA scaffolds were prepared via a thermally induced phase separation technique and were characterized by scanning electron microscopy and fluorescence microscopy. The tissue reactions and bone conductivities of both baicalin-modified PDLLA scaffolds and native PDLLA scaffolds were comparably evaluated with histological assay and histomorphometry at different implantation intervals (2, 4, 8 and 12 weeks). Osteocalcin assay, a method to evaluate the bone formation potential, has shown that the osteocalcin production in the baicalin-modified 3D PDLLA scaffold group was significantly higher (p <0.01 or <0.05) than that in the control. Histological observation and histomorphometry results reflected a higher bone formation potential and better biocompatibility of baicalin-modified PDLLA scaffold when compared with those of the native PDLLA scaffolds. [Copyright &y& Elsevier]

The objective of this study was to investigate the efficiency of two treatments for poly(d,l-lactic acid) (PDLLA) surface modification using silk fibroin, one chemical treatment and one physical treatment: 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (WSC) and entrapment. The properties of control films, WSC-modified and entrapment-treated PDLLA films were investigated by water contact angle measurement and electron spectroscopy for chemical analysis (ESCA). The water-contact angle measurement indicated the change of hydrophilicity and the ESCA analysis suggested that the modified PDLLA film using silk fibroin became enriched with nitrogen atoms. The biocompatibility of PDLLA film might be altered, which in turn would affect the functions of cells that were seeded on it. Therefore, attachment and proliferation of osteoblasts that were seeded on modified PDLLA films and control films were examined. Cell viability was evaluated by the MTT assay and differentiated cell function was assessed by measuring alkaline phosphatase activity. These results suggested that silk fibroin was used to modify PDLLA surface via WSC and that entrapment could improve the interactions between osteoblasts and PDLLA films. The entrapment treatment was more effective than WSC treatment to accomplish the goal of surface modification. [Copyright &y& Elsevier]

Intervertebral disc (IVD) degeneration is one of the major causes of low back pain. As current clinical treatments are aimed at restoring biomechanical function and providing symptomatic relief, the methods focused on biological repair have aroused interest and several tissue engineering approaches using different cell types have been proposed. Owing to the unsuitable nature of degenerate cells for tissue engineering, attention has been given to the use of mesenchymal stem cells (MSCs). In this connection, we have made a study on the characteristics of MSCs derived from adult bone marrow and on the feasibility of constructing IVD tissue-engineering cell under a Three-Dimensional Pellet Culture System. The human bone marrow MSCs were isolated and purified with density gradient solution and attachment-independent culture system. MSCs isolated using this method are a homogeneous population as indicated by morphology and other criteria. They have the capacity for self-renewal and proliferation, and the multilineage potential to differentiate.

Objective: To detect the effect of mechanical stretch on shape, alignment, proliferation, and metabolism of tendon cells maintained in three-dimensional culture., Methods: A cyclic mechanical strain apparatus for three-dimensional cell cultures was developed. Based on the apparatus, a specific stretch pattern (10% elongation, 12 stretches/min for 15 min of each hour) was applied to tenocytes-scaffolding composites., Results: Initial studies demonstrated that the stretch-mediated effects on cell division, DNA synthesis, and metabolism in such cultures were influenced by the amplitude, frequency, periodicity, and duration of the applied stretch. After 48 hours' exposure to the stretch, the cell number and [3H] thymidine incorporation into DNA were increased, compared with those of the nonstretched controls(P < 0.05). Under the stretch pattern, the shape of cells changed to oblate and spread to the direction of the stretch. The cyclic stretch also caused an increase in collagen synthesis by tendon cells (P < 0.05), which was predominant in type I., Conclusion: Cyclic mechanical stretches act directly to stimulate tendon cell growth and these results are compatible with a significant role for stretch in tissue-engineered tendon construction.

This article introduces a three-dimensional scaffold which is used to perform three-dimensional cell culture under mechanical stretch from the point of construction of tissue-engineered tissue. The composition, structure, surface characteristics, mechanical property, and cell compatibility of the scaffold have been studied by using surface chemistry and material mechanics testing methods. The results indicate that the polyvinyl alcohol (PVA) sponge, which is water-tolerant, coated with Poly-DL-lactic-co-glycolic acid (PLGA) possesses a good nature in appropriate surface feature, porosity, elastic recoil, and cell compatibility. These features provide wide options for using this scaffold to study the effects of mechanical stretch on cells maintained in three-dimensional culture to provide a three-dimensional matrix.