Modeling dermal granulation tissue with the linear fibroblast-populated collagen matrix: A comparison with the round matrix model

Abstract

Wound contraction typically is not symmetrical; for example, a square-shaped wound will not yield a square scar. Interestingly, the round fibroblast-populated collagen matrix has been used as a model of wound contraction, even though contraction in this model is mostly symmetrical. We wanted to compare the round versus linear fibroblast-populated collagen matrix to see which would be a better model of dermal granulation tissue. Gross and microscopic morphology, contraction kinetics, cytoskeletal architecture, and apoptotic and proliferative indices were compared between the round versus the linear fibroblast-populated collagen matrix. A rat excisional wound model was used as an in vivo standard of healing. The rate of contraction was similar between the two models, although the mode of contraction was grossly asymmetric in the linear while remaining symmetric in the round model. Cellular survival and proliferation were both dependent on matrix attachment in both models; this was analogous to the attachment-dependence of granulation tissue. In the attached (restrained) condition, the level of cellular organization was higher in the linear than in the round matrix; the tissue architecture of the linear matrix, moreover, mimicked that of the excisional wound model. The round versus linear fibroblast-populated collagen matrix displayed a similar proliferative and survival response to matrix attachment. The latter model, however, demonstrated tissue organization with attachment and asymmetrical contraction after detachment analogous to that of the in vivo wound model. The linear fibroblast-populated collagen matrix appears to be the better model of dermal granulation tissue.