Ultrasound stimulation of types I and III collagen expression of tendon cell and upregulation of transforming growth factor beta

Ultrasound in contemporary physiotherapy practice

The use of therapeutic ultrasound as an element of physiotherapy practice is well established, but the nature of that practice has changed significantly over the last 20 years. This paper aims to review the rationale and range of applications for which this modality is employed in current practice. Whereas in the past, its primary use was as a thermal modality, it is argued that currently, it is the 'non-thermal' aspects of the intervention that are most commonly employed. The predominant use of therapeutic ultrasound is in relation to tissue repair and soft tissue lesion management, where the evidence would support its application in the inflammatory, proliferative and remodelling phases. The clinical outcomes appear to be dose dependent, and whilst this paper does not detail dose related clinical decision making, the broad issues are considered. The future possibilities for the use of the modality are reviewed, and although outside the immediate remit of this paper, the use of therapeutic ultrasound in fracture management is briefly considered.

Therapeutic ultrasound stimulation of tendon cell migration

Ultrasound is a therapeutic agent commonly used to treat sports-related tendinopathy. Tendon healing requires tendon cells migration to the repair site, followed by the proliferation and synthesis of extracellular matrix. This study was designed to determine the effect of ultrasound on migration of tendon cells intrinsic to rat Achilles tendon. Furthermore, the existence of a correlation between this effect and the expression of the contractile actin isoform, alpha-smooth muscle (SM) actin, which is associated with cell mobility, was also examined. Cell migration was evaluated by transwell filter migration assay. The mRNA expressions of alpha-SM actin were determined by reverse transcription-polymerase chain reaction. Dose-dependent ultrasound enhancement of tendon cells migration through the transwell filter was demonstrated. Using immunofluorescence stain for alpha-SM actin, the percentages of alpha-SM actin-positive cells of total cells, nonmigrated cells, and migrated cells on the filter were calculated. Ultrasound-treated cells which had migrated to the bottom side of the filter were more likely to express alpha-SM actin than migrated control cells and nonmigrated cells. However, there was no change of mRNA and protein expression of alpha-SM actin as well as expression of FAK and p-FAK. In conclusion, ultrasound stimulates tendon cell migration in association with increased expression of alpha-SM actin of tendon cells.

The pentapeptide KTTKS promoting the expressions of type I collagen and transforming growth factor-beta of tendon cells

Pentapeptide KTTKS, a subfragment of type I collagen propeptide, has been demonstrated to promote the extracellular release of collagen in fibroblasts. The present study was designed to investigate the effect and molecular mechanism of KTTKS on type I collagen expression of rat Achilles tendon cells. Genes related to the upregulation of collagen expression such as transforming growth factor-beta (TGF-beta), and mRNA-binding proteins (mRBP) E1 and K were also examined. MTT assay revealed cell viability was not affected by KTTKS treatment. Protein expression of type I collagen was determined by immunocytochemistry and Western blot analysis. Results showed that KTTKS induced type I collagen expression of tendon cells. The mRNA expressions of alpha1(I) procollagen, TGF-beta, mRBP K, as determined by reverse transcription-polymerase chain reaction (RT-PCR), were also enhanced after KTTKS treatment. The stability of preexisting alpha1(I) procollagen mRNA after the addition of alpha-amanitin was analyzed by RT-PCR at 24 and 48 h. Results showed that KTTKS slowed down the degradation of alpha1(I) procollagen mRNA (p = 0.021). Furthermore, the concentration of TGF-beta in conditioned medium, as determined by enzyme-linked immunosorbent assay, increased dose dependently in cells treated with KTTKS (p = 0.001). In conclusion, KTTKS promotes the expression of type I collagen and maintains its mRNA stability in a process associated with the upregulation of TGF-beta.

Therapeutic Ultrasound Applications in Craniofacial Growth, Healing and Tissue Engineering

Previous reports have shown that therapeutic ultrasound enhances healing of fractured bone as well as cut tendons. Moreover, it has been shown that therapeutic ultrasound enhances bone formation during distraction osteogenesis that is also known as Ilizarove technique. It has been recently reported that therapeutic ultrasound enhances tooth formation and eruption during mandible distraction osteogenesis in rabbits. This enhanced tooth formation and eruption was caused by new dental tissue formation, known as dentin and cementum. This led to a clinical trial in human that showed that therapeutic ultrasound can enhance repairing tooth root resorption caused by orthodontic treatment. This discovery can lead to many applications of ultrasound in the dental as well as in the craniofacial reconstructions. This paper provides an overview of the molecular basis of the achieved clinical results. Moreover, potential future application will be elaborated.