Optimizing wound repair includes more rapid closure of chronic wounds and the prevention of excess scarring in acute wounds. Collagen arrangement in dermis is in a basket weave pattern, which is responsible for skin being pliable. The haphazard organization of collagen in scar is responsible for the non-pliable nature of fibrotic tissues. The hypothesis is that fibroblast orientation controls the organization of the collagen matrix. We found treating adult rat wounds with HA (hyaluronate) or LiCl produced a granulation tissue collagen matrix that had a dermal-like quality to its organization. In vitro HA and LiCl promoted gap junctional communication (GJC) between cultured demal fibroblasts. What is the relationship between GJC, fibroblast orientation and the organization of deposited collagen? Gap junctions are gated channels connecting neighboring cells that facilitate direct exchange of small molecules of less than 1,000 Da. Gap junctions are established by the docking of connexons composed of 6 connexin (CX) transmembrane proteins. Gap junction channels are gated and can rapidly switch from an opened to a closed state. Fibroblasts in human dermis are extensively coupled through GJC in an open state. During fish scale embryonic development, the collagen matrix is deposited in orthogonal arrays, where sheets of collagen fibers are arranged 90 degrees to one another, creating a plywood-like pattern. The ordered organization of that collagen matrix is dependent upon the orientation of resident fibroblasts, which may be related to GJC and microtubules. It is proposed that GJC transfer signals between fibroblasts that dictate the arrangement of their microtubules within the cytoskeleton. Fibroblasts with a predetermined orientation will deposit a collagen matrix with an ordered organization. The disruption of GJC leads to altered cell orientation and impaired collagen organization, as we reported with the contraction of fibroblast populated collagen lattices (FPLC) with cells unable to express CX43. We will investigate the role of GJC in the repair process through tissue culture models, rat PVA sponge implants and wounded CX43 null fetal mouse limb explants. In addition, we will document that the association of gap junctions with microtubules creates a cytoskeleton that dictates the ordered orientation of fibroblasts. We will also document that replacing cell surface gap junctions with cadherins, Ca dependent adhesion molecules, which associate with microfilament stress fibers, will create a cytoskeleton that dictates randomly orientated fibroblasts and a haphazard collagen organization. Enhancing wound fibroblast GJCs should produce a more skin-like pliable scar.
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