title: A histologic analysis of three-dimensional versus two-dimensional tissue expansion in the porcine model.
abstract: OBJECTIVE
  Recently, a two-dimensional Silastic Dacron stretching skin device has been developed for scalp reduction surgery. Attached subgaleally, this device stretches skin over time, while avoiding the visible volumetric distention that is typical of three-dimensional tissue expanders. Unlike three-dimensional expanders, the histological changes observed with a two-dimensional stretching device have not been described in the literature. The present study compares the histological effects of two-dimensional and three-dimensional skin tissue expansion in the porcine model.
  
  
  METHODS
  A university Institutional Review Board-approved study in which 16 domestic piglets were used. The 16 piglets were divided evenly into four cohorts as follows: 1, 1-week control cohort; 2, 1-week experimental cohort; 3, 4-week control cohort; and 4, 4-week experimental cohort.
  
  
  METHODS
  Tissue expanders (three-dimensional) and Dacron Silastic tissue stretchers (two-dimensional) were surgically inserted into the lateral skin of 16 domestic pigs. Animals were killed at either 1 or 4 weeks based on group assignment. Light microscopic ocular micrometry and stereological point counting were used to determine the depth of the epidermis, dermis, and subdermal adipose tissue layer; width of the panniculus muscle; diameter of sweat gland follicles; percentage ratio of dermal collagen, blood vessels, and tissue space; and epidermal mitotic index in 100 specimens. One-way ANOVA was used to evaluate statistical differences.
  
  
  RESULTS
  Both tissue expanders yielded increased values compared with control subjects, with respect to epidermal, dermal, and fat widths and blood vessel counts, whereas adnexal structures in the panniculus muscle width were unaltered.
  
  
  CONCLUSIONS
  Although statistically the two types of expansion produced histologically similar changes, the degree of change varied according to the type of expander that was used and the duration of tissue expansion. Most notably, three-dimensional expansion produced more tissue gain per unit area expanded at both the 1-week and the 4-week time intervals, and early (1-week) two-dimensional tissue expansion stimulated a greater angiogenic response than three-dimensional expansion. These findings will assist the surgeon in understanding the physical changes that occur with these two forms of tissue expansion, as well as the potential clinical advantages and shortcomings of each method.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, University of Illinois at Chicago, USA.
authors.forename: J C
authors.initials: JC
authors.lastname: Alex
authors.forename: T K
authors.initials: TK
authors.lastname: Bhattacharyya
authors.forename: G
authors.initials: G
authors.lastname: Smyrniotis
authors.forename: K
authors.initials: K
authors.lastname: O'Grady
authors.forename: R J
authors.initials: RJ
authors.lastname: Konior
authors.forename: D M
authors.initials: DM
authors.lastname: Toriumi
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology; D000704:Analysis of Variance; D000818:Animals; D001808:Blood Vessels / Q000033:anatomy & histology; D015331:Cohort Studies; D003094:Collagen / Q000648:ultrastructure; D062109:Dermatologic Surgical Procedures; D020405:Dermis / Q000033:anatomy & histology; D004129:Dimethylpolysiloxanes; D000078404:Epidermal Cells; D004817:Epidermis / Q000033:anatomy & histology; D004867:Equipment Design; D005500:Follow-Up Studies; D008940:Mitotic Index; D023421:Models, Animal; D018482:Muscle, Skeletal / Q000033:anatomy & histology; D018919:Neovascularization, Physiologic; D011093:Polyethylene Terephthalates; D012828:Silicones; D012867:Skin / Q000033:anatomy & histology* / Q000098:blood supply; D013545:Sweat Glands / Q000033:anatomy & histology; D013552:Swine; D013997:Time Factors; D015626:Tissue Expansion / Q000379:methods*; D015625:Tissue Expansion Devices / Q000145:classification
chemical_list: D004129:Dimethylpolysiloxanes; D011093:Polyethylene Terephthalates; D012828:Silicones; C013830:baysilon; D003094:Collagen