Peripheral blood fibrocytes from burn XXXX : identification and quantification of fibrocytes in adherent cells cultured from peripheral blood mononuclear cells.

@entity1 @entity2318 @entity2533 @entity5750
Peripheral blood fibrocytes are a newly identified leukocyte subpopulation that displays fibroblast-like properties. These blood-borne cells can rapidly enter the site of injury at the same time as circulating inflammatory cells. We hypothesize that circulating fibrocytes represent an important source of fibroblasts for healing of extensive burn wounds where it may be difficult for fibroblasts to migrate from the edges of uninjured tissue. In this study we identified and quantified fibrocytes among the adherent cells cultured from @entity1 peripheral blood mononuclear cells (PBMC) obtained from 18 burn @entity1 and 12 normal individuals, based on their ability to express type I collagen. Our results showed that adherent cells cultured from PBMC of burn @entity1 differentiated to fibrocytes more efficiently than did those from normal individuals. The percentage of type I collagen-positive fibrocytes was significantly higher for @entity1 than for controls (89.7 +/- 7.9% versus 69.9 +/- 14.7%, p < 0.001). This percentage was consistently higher for @entity1 with a >/=30% total body surface area burn until 1 year, with the highest percentage appearing within 3 weeks of injury. A positive correlation was found between the levels of serum @entity2533 ( @entity2533 ) and the percentage of fibrocytes developing in the cultures of PBMC derived from these @entity1 . We also demonstrated that fibrocytes were derived from @entity5750 (+) cells but not @entity5750 (-) cells. Conditioned medium from @entity5750 (-) cells was, however, required for fibrocyte differentiation, whereas direct contact between @entity5750 (-) and @entity5750 (+) cells was not necessary. Treatment of the cell cultures with @entity2533 enhanced the development of collagen-positive cells, whereas the inclusion of neutralizing anti- @entity2533 antibodies in the @entity5750 (-) conditioned medium suppressed fibrocyte differentiation. These data suggest that the development of fibrocytes is up-regulated systemically in burn @entity1 . Increased @entity2533 in serum stimulates the differentiation of the @entity5750 (+) cell population in PBMC into collagen-producing cells that may be important in wound healing and @entity2318 .
