Microfilament rearrangements during fibroblast‐induced contraction of three‐dimensional hydrated collagen gels

Abstract

In vitro models have been developed recently to study the ability of fibroblasts to generate tensile force within collagen gels. The present study was initiated to assess the role of the cytoskeleton in the cell shape changes and force generation in one such model system. Porcine periodontal ligament fibroblasts ( PPLF ) were cultured within three-dimensional collagen gels attached to glass coverslips. Fluorescence microscopy, using nitrobenzooxadizole (NBD)- phallacidin labeling for microfilaments and tubulin antibody staining for microtubules, was combined with phase and Nomarski optics to determine the intra- and extracellular architecture of the cells and collagen fibers. Samples were observed from 30 minutes to 24 hours after initiation of cell attachment. During attachment and spreading, NBD- phallacidin staining changed dramatically until large microfilament bundles became prominent. Collagen fiber alignment, compaction, and finally tearing from the coverslip occurred during this time. After release of tension, microfilament bundles were no longer evident. The change in microtubule distribution during these processes was less dramatic, appearing to follow the change in cell shape. These results indicate that microfilaments play an essential role in generating force to align and compact collagen, while microtubules may have a secondary role only.

Contraction of collagen gels by intestinal epithelial cells depends on microfilament function

“…The experimental system that we developed has several advantages, including the availability of a commercially prepared collagen; the rapid, reproducible extent of contraction; the well-defined gel composition; and the easily measured and reproducible end point. The collagen concentration used in this model, which is lower, and the cell number, which is higher, than those previously reported using fibroblasts (8,27), permit the determination of gel contraction within 24 hr.…”

“…Specifically, IEC-6 cells, a rat intestinal crypt cell line (3), require binding to laminin for organization into multicellular epithelial sheets (4). Tractional forces generated by cells play critical roles in both embryogenesis (5,6) and wound healing (7,8). Fibroblasts grown on type I collagen gels extensively modify the collagen gels (7)(8)(9)(10)(11)(12)(13)(14)(15).…”

“…Tractional forces generated by cells play critical roles in both embryogenesis (5,6) and wound healing (7,8). Fibroblasts grown on type I collagen gels extensively modify the collagen gels (7)(8)(9)(10)(11)(12)(13)(14)(15). This contraction of collagen gels composed of reconstituted collagen fibrils by fibroblasts in vitro is used by many Manuscript received August 16, 1991; revised manuscript received August 5, 1992; accepted August 10, 1992.…”

Fibroblasts, myofibroblasts, and wound contraction

“…In marked contrast, cells in anchored matrices become bipolar and orient along lines of tension (Stopak and Harris, 1982;Bellows et al, 1982). Cells develop prominent stress fibers and fibronexus junctions and resemble myofibroblasts (Farsi and Aubin, 1984;Mochitate et al, 1991;Tomasek et al, 1992). Therefore, fibroblasts can contract a tissue matrix in vitro without differentiating into myofibroblasts, and the appearance of myofibroblasts correlates with development of stress in the matrix.…”

Hydroxyapatite-Nanotube Composites and Coatings for Orthopedic Applications

“…The main reasons for which BNNT was chosen are: (i) excellent elastic modulus (750-1200 GPa [134][135]), (ii) excellent tensile strength (>24 GPa [136]), similar range to CNT, and (iii) positive reports on its biocompatibility [137][138][139][140][141]. It is emphasized that no study existed on HA-BNNT composite before the work reported in this dissertation.…”