The effects of tissue stretch on fibroblast morphology

For those of you who have not read the work of  Dr. Helene M. Langevin who is the research associate professor in the department of Neuology at McGill University, I high suggest that you take the time to do so.  Her studies on dynamic connective tissue changes and intercellular communication with tissue deformation are on the cutting edge and are of great importance for furthering our understanding of the effects of many manual therapy techniques.

In this study from 2005, she investigates the effect of stretch on fibroblast morphology using ex vivo and in vivo rat models.

Dynamic fibroblast cytoskeletal response to subcutaneous tissue stretch ex vivo and in vivo Am J Physiol Cell Physiol 288:C747-C756.

As is stated in the article, Cytoskeleton-dependent changes in cell shape are well-established factors regulating a wide range of cellular functions including signal transduction, gene expression, and matrix adhesion.  It is also becoming increasingly apparent that both mechanical forces generated within the cytoskeleton of cells and externally applied forces are important determinants of cell shape and cell function. However little has been done to demonstrate these changes in whole tissues.

This study demonstrates the effect of prolonged stretches on actual tissue samples.  They discovered that the fibroblasts in the stretched tissue had larger, “sheetlike” cell bodies with shorter processes, contrasting the non stretched tissue which had a “dendritic” morphology with smaller, more globular cell bodies and longer processes.

As is the case with all other tissues, when load is applied, the body seems to respond by adding more of the stressed tissues in order to compensate.  Take for example strength training: increasing loads over time leads to the addition of new muscle cells as well as an increase in their cross-section measurements.  Such has also been shown to occur in bone, ligaments, tendons, etc.

These findings help to justify application of various soft tissue and rehabilitative techniques as it demonstrates how tissues can adapt to applied loads.  As stated in the article “The dynamic, cytoskeleton-dependent responses of fibroblasts to changes in tissue length demonstrated in this study have important implications for our understanding of normal movement and posture, as well as therapies using mechanical stimulation of connective tissue including physical therapy, massage, and acupuncture.”