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The specific targeting and inactivation of gene expression represents nowadays the goal of the mainstream basic and applied biomedical research. Both researchers and pharmaceutical companies, taking advantage of the vast amount of genomic data, have been focusing on effective endogenous mechanisms of the cell that can be used against abnormal gene expression. In this context, RNA represents a key molecule that serves both as tool and target for deploying molecular strategies based on the suppression of genes of interest. The main RNA-mediated therapeutic methodologies, deriving from studies on catalytic activity of ribozymes, blockage of mRNA translation and the recently identified RNA interference, will be discussed in an effort to understand the utilities of RNA as a central molecule during gene expression.

The present study investigates the effect of transosseous low-intensity pulsed ultrasound (LiUS) during lingamentization process on the healing at tendon graft-bone interface in rabbits. Analysis of the RT-PCR products showed statistically significant up-regulation of genes encoding collagen type I and tRNAGly in the study group compared to the control group. Histological examination indicated a faster healing rate and a more efficient lingamentization process after ultrasound treatment. Our results suggest that transosseous application of LiUS enhances the healing rate of the tendon graft-bone interface, possibly by affecting the expression levels of significant genes.

The present study investigates the effect of transosseous low-intensity pulsed ultrasound (LiUS) on the healing at tendon graft-bone interface, in molecular and histological level. The anterior cruciate ligament (ACL) in both knees of 52 New Zealand White rabbits was excised and replaced with the long digital extensor. A custom-made ultrasound transducer was implanted onto the medial tibial condyle, adjacent to the surface of the bone tunnel at both knees of the rabbits. The LiUS-treated right knees received 200-mus bursts of 1 MHz sine waves at a pulse repetition rate of 1 kHz and with 30 mW/cm(2) spatial-average temporal-average intensity for 20 min daily (study group), while the left knee received no LiUS (control group). Thirty-six rabbits were used to perform semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) analysis from both study and control groups for transforming growth factor-beta1 (TGF-beta1), biglycan and collagen I. RT-PCR products showed statistically significant upregulation of biglycan and collagen I gene expression in the study group, while TGF-beta1 gene expression exhibited a bimodal profile. Histological examination performed in 16 rabbits from both groups supported the findings of the molecular analysis, indicating a faster healing rate and a more efficient ligamentization process after ultrasound treatment. These findings suggest that transosseous application of LiUS enhances the healing rate of the tendon graft-bone interface, possibly by affecting the expression levels of genes significant for the tendon to bone healing process.