Stimulation of osteoblast differentiation with guided ultrasound waves

BACKGROUND: Ultrasound induces mechanical vibration and heat, causing differentiation and proliferation in osteoblasts. All known in vitro evaluations of ultrasound are, however, performed with longitudinal ultrasound waves. We addressed a question: Do other forms of ultrasound waves, such as guided waves (longitudinal and guided flexural) transduced at a remote location, enhance differentiation of osteoblast cells? METHODS: In this study, we employed guided Lamb waves that were induced in a borosilicate glass slide (cortical bone mimic). An average energy of 10-30 mW/cm(2) for 20 min per day was applied to MC3T3 osteoblast-like cells, which were placed 30-75 mm distant from the transducer. RESULTS: The result revealed that guided waves significantly stimulated the differentiation and mineralization of MC3T3 cells. In particular, guided waves elevated mRNA expression levels of bone formation-related genes such as alkaline phosphatase, osteopontin, osteocalcin, osteoprotegerin, and bone sialoprotein on days 8 and 16. In addition, the amount of mineralization found via Alizarin red staining was increased by 157 % (p = 0.034). The amount of mineralization was found to be independent of distance from the transducer (p = 0.967). CONCLUSION: We demonstrate herein that ultrasound in a form of guided Lamb waves is capable of inducing osteoblast differentiation in vitro, and it may enable the stimulation of osteoblasts in vivo over a distance from the site of ultrasound application

Xyloglucan Based In Situ Gel of Lidocaine HCl for the Treatment of Periodontosis

The present study was aimed at formulating thermoreversible in situ gel of local anesthetic by using xyloglucan based mucoadhesive tamarind seed polysaccharide (TSP) into periodontal pocket. Temperature-sensitive in situ gel of lidocaine hydrochloride (LH) (2% w/v) was formulated by cold method. A full 3 2 factorial design was employed to study the effect of independent variables concentrations of Lutrol F127 and TSP to optimize in situ gel. The dependent variables evaluated were gelation temperature ( 1 ) and drug release ( 2 ). The results revealed the surface pH of 6.8, similar to the pH of saliva. Viscosity study showed the marked increase in the viscosity of gel at 37 ∘ C due to sol-gel conversion. TSP was found to act as good mucoadhesive component to retain gel at the site of application in dental pocket. Gelation of formulation occurred near to body temperature. In vitro study depicted the fast onset of drug action but lasting the release (90%) till 2 h. Formulation F7 was considered as optimized batch, containing 18% Lutrol F127 and 1% tamarind seed polysaccharide. Thus, lidocaine hydrochloride thermoreversible in situ gel offered an alternative to painful injection therapy of anesthesia during dental surgery, with fast onset of anesthetic action lasting throughout the dental procedure

Sperm Cell Driven Microrobots-Emerging Opportunities and Challenges for Biologically Inspired Robotic Design

With the advent of small-scale robotics, several exciting new applications like Targeted Drug Delivery, single cell manipulation and so forth, are being discussed. However, some challenges remain to be overcome before any such technology becomes medically usable; among which propulsion and biocompatibility are the main challenges. Propulsion at micro-scale where the Reynolds number is very low is difficult. To overcome this, nature has developed flagella which have evolved over millions of years to work as a micromotor. Among the microscopic cells that exhibit this mode of propulsion, sperm cells are considered to be fast paced. Here, we give a brief review of the state-of-the-art of Spermbots - a new class of microrobots created by coupling sperm cells to mechanical loads. Spermbots utilize the flagellar movement of the sperm cells for propulsion and as such do not require any toxic fuel in their environment. They are also naturally biocompatible and show considerable speed of motion thereby giving us an option to overcome the two challenges of propulsion and biocompatibility. The coupling mechanisms of physical load to the sperm cells are discussed along with the advantages and challenges associated with the spermbot. A few most promising applications of spermbots are also discussed in detail. A brief discussion of the future outlook of this extremely promising category of microrobots is given at the end

Micropatterned Neurovascular Interface to Mimic the Blood–Brain Barrier’s Neurophysiology and Micromechanical Function: A BBB-on-CHIP Model

A hybrid blood–brain barrier (BBB)-on-chip cell culture device is proposed in this study by integrating microcontact printing and perfusion co-culture to facilitate the study of BBB function under high biological fidelity. This is achieved by crosslinking brain extracellular matrix (ECM) proteins to the transwell membrane at the luminal surface and adapting inlet–outlet perfusion on the porous transwell wall. While investigating the anatomical hallmarks of the BBB, tight junction proteins revealed tortuous zonula occludens (ZO-1), and claudin expressions with increased interdigitation in the presence of astrocytes were recorded. Enhanced adherent junctions were also observed. This junctional phenotype reflects in-vivo-like features related to the jamming of cell borders to prevent paracellular transport. Biochemical regulation of BBB function by astrocytes was noted by the transient intracellular calcium effluxes induced into endothelial cells. Geometry-force control of astrocyte–endothelial cell interactions was studied utilizing traction force microscopy (TFM) with fluorescent beads incorporated into a micropatterned polyacrylamide gel (PAG). We observed the directionality and enhanced magnitude in the traction forces in the presence of astrocytes. In the future, we envisage studying transendothelial electrical resistance (TEER) and the effect of chemomechanical stimulations on drug/ligand permeability and transport. The BBB-on-chip model presented in this proposal should serve as an in vitro surrogate to recapitulate the complexities of the native BBB cellular milieus