Cell, matrix changes and alpha‐smooth muscle actin expression in repair of the canine meniscus

Abstract

Processes in the repair of a crevice in the knee joint meniscus were investigated in 10 dogs. Two 2-mm cylindrical plugs from each medial meniscus were removed, rendered acellular by freezing and thawing, and then reinserted into the meniscus. Dogs were euthanized at intervals of 3-52 weeks after surgery. The crevice between the plug and meniscus at 3 weeks after surgery was filled with a tissue containing alpha-smooth muscle actin-positive cells. One year after surgery, the plug had remodeled and was populated with spindle-shaped and fibrochondrocyte-like cells. The plug had an appearance intermediate between that of hyaline and fibrocartilage at this time, with a seamless integration in sites between the remodeled plug and the surrounding meniscus. alpha-smooth muscle actin-positive cells were concentrated at the interface of the remodeled plug and adjacent meniscus and at the surface of the plug. Therefore, remodeling of both the plug and meniscal tissue and the participation of alpha-smooth muscle actin-positive cells appear essential for integration of the plug into the adjacent meniscal tissue. Cells in the superficial zone of the meniscus seem to be active in the repair process. A change in both the phenotype of the cells and the quality of the matrix toward a more hyaline state appears to be an integral part of the remodeling process in the meniscus.

Enhanced integrative repair of the porcine meniscus in vitro by inhibition of interleukin‐1 or tumor necrosis factor α

“…Cell accumulation, presumably due to a combination of migration and proliferation, appears to be an important component of meniscal repair in vivo, and previous studies have shown complete repopulation of meniscal allografts (45) or a devitalized meniscal plug that was reinserted into the meniscus in an animal model (46). In the present study, cell accumulation at the interface was associated with increased tissue formation and interfacial shear strength of repair.…”

Development and Characterization of an Acellular Porcine Medial Meniscus for Use in Tissue Engineering

“…Early studies investigating the use of xenogeneic meniscal tissue aimed only to kill the xenogeneic cells using freeze-thaw techniques and made no attempts to remove residual xenoantigens. 37,38 However, the presence of foreign antigens may result in antibody-dependant inflammation that has the potential to result in tissue damage and calcification. The challenge was to decellularize the dense fibrous matrix of the porcine medial meniscus whilst also removing major xenoantigens, leaving an acellular, biocompatible scaffold.…”

Comparative spatial and temporal localisation of perlecan, aggrecan and type I, II and IV collagen in the ovine meniscus: an ageing study

“…A number of histological studies have also attempted to define the fine structure of the meniscus (Cheung 1987;Bland and Ashhurst 1996;Wildey and McDevitt 1998;Kambic et al 2000;Wildey et al 2001;Ahluwalia et al 2001;Hellio Le Graverand et al 2001a, b, c, d;Naumann et al 2002;Rijk et al 2004;Meister et al 2004;Kobayashi et al 2004;Kambic and McDevitt 2005). The material properties of the meniscus, however, make it a technically demanding tissue to be examined histologically and particular care must be taken to ensure that artefacts are not introduced into specimens during histological processing.…”

“…Kambic et al (2000) and Ahluwalia et al (2001) demonstrated that a proportion of meniscal cells expressed a-smooth muscle cell actin and a similar contractile phenotype to myofibroblasts with possibly a role to play in wound retraction. Four classes of cells have been identified in the rabbit meniscus by visualisation of cytoskeletal proteins, cytoplasmic extensions and gap junctions between the various cell types (Hellio Le Graverand et al 2001a, d).…”