QUANTITATIVE-ANALYSIS OF COLLAGEN GEL CONTRACTILE FORCES GENERATED BYDERMAL FIBROBLASTS AND THE RELATIONSHIP TO CELL MORPHOLOGY

The force generated in granulation tissue during wound contraction is thought to be cell mediated; however, it is unclear whether contractil e forces are generated by fibroblast locomotion or contraction of myof ibroblasts. To help clarify this question the force of this contractio n can now be determined accurately in a human dermal fibroblast collag en lattice system using a novel instrument known as a Culture Force Mo nitor. Three distinct phases of contraction of such collagen gels coul d be identified over the first 24 hours. Most of the force generated b y human dermal fibroblasts was produced during the first stage in para llel with cell attachment and associated changes in cell shape, and th e appearance of cell processes. During this initial 24 hours no eviden ce could be found for the presence of myofibroblasts, but stereoscopic and electron microscopic analysis at a range of time points indicated that migratory fibroblasts were present in the system. Comparison of the contraction profiles of cells extracted from other tissues (tendon and articular cartilage), and extracted by different means from the s ame tissue specimen, indicated that different populations of fibroblas ts can be distinguished on the basis of their pattern of contractions. It would seem that most of the force generated in this model is a res ult of fibroblast attachment and movement within the collagen lattice. Furthermore, different groups of fibroblasts, even within the same ti ssue, may vary in their contraction (hence locomotory) activity. (C) 1 996 Wiley-Liss, Inc.