Biological advantages of porous hydroxyapatite scaffold made by solid freeform fabrication for bone tissue regeneration.

Presently, commercially available porous bone substitutes are manufactured by the sacrificial template method, direct foaming method, and polymer replication method (PRM). However, current manufacturing methods provide only the simplest form of the bone scaffold and cannot easily control pore size. Recent developments in medical imaging technology, computer-aided design, and solid freeform fabrication (SFF), have made it possible to accurately produce porous synthetic bone scaffolds to fit the defected bone shape. Porous scaffolds were fabricated by SFF and PRM for a comparison of physical and mechanical properties of scaffold. The suggested three-dimensional model has interconnected cubic pores of 500 µm and its calculated porosity is 25%. Whereas hydroxyapatite scaffolds fabricated by SFF had connective macropores, those by PRM formed a closed pore external surface with internally interconnected pores. SFF was supposed to be a proper method for fabricating an interconnected macroporous network. Biocompatibility was confirmed by testing the cytotoxicity, hemolysis, irritation, sensitization, and implantation. In summary, the aim was to verify the safety and efficacy of the scaffolds by biomechanical and biological tests with the hope that this research could promote the feasibility of using the scaffolds as a bone substitute.

Control of neonatal human dermal fibroblast migration on poly(lactic-co-glycolic acid)-coated surfaces by electrotaxis.

Many types of cells respond to applied direct current electric fields (dcEFs) by directional cell migration, a phenomenon called galvanotaxis or electrotaxis. In this study, electrotaxis was used to control cell migration. We designed a new electrotaxis incubator and chamber system to facilitate long-term (> 12 h) observation and to allow for alterations to the direction of the current. Poly(lactic-co-glycolic acid) (PLGA) was coated onto surfaces to mimic a commonly used tissue-engineering scaffolding environment. Neonatal human dermal fibroblasts (nHDFs) were grown on PLGA-coated surfaces and exposed to EFs at increasing currents in the range 0-1 V/cm. These cells migrated toward the cathode during 3 h of dcEF stimulation; however, the migration speed decreased with increasing electric fields. Cells exposed to dcEFs in the range 1-2 V/cm showed no changes to migration speed or x forward migration indices (xFMIs) and the cells continued to move toward the cathode. nHDFs showed directional migration towards the cathode in direct current (dc) EFs (1 V/cm) and they moved in the opposite direction when the polarity of the dcEF was reversed. Reorganization of the actin cytoskeleton and polarization of the Golgi apparatus were evaluated by immunostaining, which showed that the actin cytoskeleton elongated towards the cathode and the Golgi apparatus polarized in the direction of the dcEF. This study revealed that cell migration could potentially be controlled on PLGA scaffolds through electrotaxis. Copyright © 2015 John Wiley & Sons, Ltd.

Titanium surface modification by using microwave-induced argon plasma in various conditions to enhance osteoblast biocompatibility.

BACKGROUND: Titanium is a well proven implantable material especially for osseointegratable implants by its biocompatibility and anti-corrosive surface properties. Surface characteristics of the implant play an important role for the evolution of bone tissue of the recipient site. Among the various surface modification methods, plasma treatment is one of the promising methods for enhance biocompatibility. We made microwave-induced argon plasma at atmospheric pressure to improve in titanium surface biocompatibility. RESULTS: Various states of emission spectra from excited species-argon, nitrogen atoms and oxygen atoms were observed. The electron energy band structures are the unique characteristics of atoms and functional groups. Microwave-induced argon plasma treatment changed the titanium surface to be very hydrophilic especially on the 5 s short treatment and 30 s, 90 s long treatment samples that detected by contact angle measurement. MC3T3-E1 attachment and proliferation assay significantly increased in 5 s at short treatment, 30 s, and 90 s at long treatment after 5 days incubation. CONCLUSIONS: Result indicated that microwave-induce argon plasma treatment would be an effective method to modify titanium surface for enhancing cell-material interactions.

Effects of direct current electric-field using ITO plate on breast cancer cell migration.

BACKGROUND: Cell migration is an essential activity of the cells in various biological phenomena. The evidence that electrotaxis plays important roles in many physiological phenomena is accumulating. In electrotaxis, cells move with a directional tendency toward the anode or cathode under direct-current electric fields. Indium tin oxide, commonly referred to as ITO has high luminous transmittance, high infrared reflectance, good electrical conductivity, excellent substrate adherence, hardness and chemical inertness and hence, have been widely and intensively studied for many years. Because of these properties of ITO films, the electrotaxis using ITO plate was evaluated. RESULTS: Under the 0 V/cm condition, MDA-MB-231 migrated randomly in all directions. When 1 V/cm of dc EF was applied, cells moved toward anode. The y forward migration index was -0.046 ± 0.357 under the 0 V/cm and was 0.273 ± 0.231 under direct-current electric field of 1 V/cm. However, the migration speed of breast cancer cell was not affected by direct-current electric field using ITO plate. CONCLUSIONS: In this study, we designed a new electrotaxis system using an ITO coated glass and observed the migration of MDA-MB-231 on direct current electric-field of the ITO glass.

Resveratrol inhibits phenotype modulation by platelet derived growth factor-bb in rat aortic smooth muscle cells.

Dedifferentiated vascular smooth muscle cells (VSMCs) are phenotypically modulated from the contractile state to the active synthetic state in the vessel wall. In this study, we investigated the effects of resveratrol on phenotype modulation by dedifferentiation and the intracellular signal transduction pathways of platelet derived growth factor-bb (PDGF-bb) in rat aortic vascular smooth muscle cells (RAOSMCs). Treatment of RAOSMCs with resveratrol showed dose-dependent inhibition of PDGF-bb-stimulated proliferation. Resveratrol treatment inhibited this phenotype change and disassembly of actin filaments and maintained the expression of contractile phenotype-related proteins such as calponin and smooth muscle actin-alpha in comparison with only PDGF-bb stimulated RAOSMC. Although PDGF stimulation elicited strong and detectable Akt and mTOR phosphorylations lasting for several hours, Akt activation was much weaker when PDGF was used with resveratrol. In contrast, resveratrol only slightly inhibited phosphorylations of 42/44 MAPK and p38 MAPK. In conclusion, RAOSMC dedifferentiation, phenotype, and proliferation rate were inhibited by resveratrol via interruption of the balance of Akt, 42/44MAPK, and p38MAPK pathway activation stimulated by PDGF-bb.

Stimulated migration and penetration of vascular endothelial cells into poly (L-lactic acid) scaffolds under flow conditions.

BACKGROUND: The initial procedure of the development of engineered tissues is cell seeding into three-dimensional polymer scaffolds. However, it is hard to make the cells invade into scaffold due to the characteristic of pore and material. Electrospun poly (L-lactic acid) scaffold and flow perfusion system were used to overcome these seeding problems. RESULTS: Before starting the experiment, we set up the parallel plate chamber system to observe endothelial cell migration under flow condition. In individual cell migration model, human umbilical endothelial cells started to migrate in the direction of flow at 8 dyne/cm(2) and we observed the cytoskeleton alignment at 8 dyne/cm(2). This study has demonstrated the possibility to evaluate and analyze cell migration using the parallel plate chamber system and we may predict in vivo cell migration under flow condition based on these results. Also the flow perfusion system was established for the effective cell seeding into at three dimensional scaffolds. Moreover, shear stress induced by flow can enhance cell migration into PLLA scaffold that is in the form of cotton. CONCLUSIONS: Result indicated that cell penetration was achieved under flow condition better and more than under static condition throughout the matrix.

Asiaticoside enhances normal human skin cell migration, attachment and growth in vitro wound healing model.

Wound healing proceeds through a complex collaborative process involving many types of cells. Keratinocytes and fibroblasts of epidermal and dermal layers of the skin play prominent roles in this process. Asiaticoside, an active component of Centella asiatica, is known for beneficial effects on keloid and hypertrophic scar. However, the effects of this compound on normal human skin cells are not well known. Using in vitro systems, we observed the effects of asiaticoside on normal human skin cell behaviors related to healing. In a wound closure seeding model, asiaticoside increased migration rates of skin cells. By observing the numbers of cells attached and the area occupied by the cells, we concluded that asiaticoside also enhanced the initial skin cell adhesion. In cell proliferation assays, asiaticoside induced an increase in the number of normal human dermal fibroblasts. In conclusion, asiaticoside promotes skin cell behaviors involved in wound healing; and as a bioactive component of an artificial skin, may have therapeutic value.