Laser thermal injury and subsequent wound healing in organotypic, skin-equivalent tissue models were monitored using optical coherence tomography (OCT), multiphoton microscopy (MPM), and histopathology. The in vitro skin-equivalent raft tissue model was composed of dermis with type I collagen and fibroblast cells and epidermis of differentiated keratinocytes. Noninvasive optical imaging techniques were used for time-dependent, serial measurements of matrix destruction and reconstruction and compared with histopathology. The region of laser thermal injury was clearly delineated in OCT images by low signal intensity. High resolution MPM imaging using second-harmonic generation revealed alterations in collagen microstructure organization with subsequent matrix reconstruction. Fibroblast cell migration in response to injury was monitored by MPM using two-photon excited fluorescence. This study illustrates the complementary features of linear and nonlinear light-tissue interaction in intrinsic signal optical imaging and their use for noninvasive, serial monitoring of wound healing processes in biological tissues.

Continuous CSC spurts of 80 milliseconds or less induce minimal, if any, epidermal or dermal damage and are unlikely to produce cryo-injury when used during dermatologic laser surgery.

Using biocompatible peptide hydrogel as a scaffold, we prepared three-dimensional synthetic skin that does not contain animal-derived materials or pathogens. The present study investigated preparation methods, proliferation, and functional expression of fibroblasts in the synthetic dermis and differentiation of keratinocytes in the epidermis. Synthetic dermis was prepared by mixing fibroblasts with peptide hydrogel, and synthetic skin was prepared by forming an epidermal layer using keratinocytes on the synthetic dermis. A fibroblast-rich foamy layer consisting of homogeneous peptide hydrogel subsequently formed in the synthetic dermis, with fibroblasts aggregating in clusters within the septum. The epidermis consisted of three to five keratinocyte layers. Immunohistochemical staining showed human type I collagen, indicating functional expression around fibroblasts in the synthetic dermis, keratinocyte differentiation in the epidermis, and expression of basement membrane proteins. The number of fibroblasts tended to increase until the second week and was maintained until the fourth week, but rapidly decreased in the fifth week. In the synthetic dermis medium, the human type I collagen concentration increased after the second week to the fifth week. These findings suggest that peptide hydrogel acts as a synthetic skin scaffold that offers a platform for the proliferation and functional expression of fibroblasts and keratinocytes.

Background and Objectives: In order to optimize photorejuvenation of human skin, a method must be developed to reliably compare the potential for epidermal preservation and dermal fibroblast stimulation of different laser devices and irradiation parameters. We describe a novel human skin tissue culture model developed for this purpose. Materials and Methods: An artificial skin model, consisting of human keratinocytes in the epidermis and human fibroblasts and rat-tail collagen in the dermis, was cultured using the floating collagen gel (RAFT) method. Repetitive low-fluence Er:YAG laser irradiation was applied to test the applicability of our RAFT model for characterization of epidermal preservation and dermal fibroblast stimulation post-laser treatment. Results: Histopathologic evaluation revealed a thin layer of epidermal keratinocyte preservation immediately after low fluence sub-ablative Er:YAG laser irradiation. Oneweek post-laser irradiation, the average increase in number of dermal fibroblasts as compared to control was statistically significant (P < 0.01). Conclusions: The RAFT model can be used to assess the potential for epidermal preservation and dermal fibroblast stimulation of different photorejuvenation devices and irradiation parameters and offers several advantages over traditional animal and human skin models. Lasers Surg.