title: Comparative host response of 2 human acellular dermal matrices in a primate implant model.
abstract: OBJECTIVE
  We examined the differences in capsule formation between 2 commercially available human acellular dermal matrices in a nonhuman primate model.
  
  
  METHODS
  Primates were implanted dorsally with a subcutaneously placed tissue expander and randomized into 3 groups, receiving skin coverage only, coverage with non-irradiated freeze-dried human acellular dermal matrix, or coverage with gamma-irradiated human acellular dermal matrix. After 9 weeks, soft tissue around the tissue expander was excised and evaluated qualitatively and quantitatively to assess extent of inflammation (CD68 antibodies and interleukin-6 levels), degradation and fibrosis (matrix metalloproteinase-1 and procollagen-1 staining), and mechanical (tensile) strength.
  
  
  RESULTS
  Histological evaluation of tissue around the tissue expander indicated differences in host response, suggesting capsule presence in the gamma-irradiated matrix group but not the freeze-dried matrix group. The extent of local inflammation was much higher in the gamma-irradiated matrix group which demonstrated mean (standard deviation) localized interleukin-6 concentration of 67.3 (53.6) vs 16.3 (6.7) pg/mg protein in the non-irradiated matrix group. There was robust degradation and fibrotic response in the gamma-irradiated matrix group versus the freeze-dried matrix group. Mechanical testing indicated mean (standard deviation) ultimate tensile strength of 12.0 (7.1) N in the gamma-irradiated matrix group versus 99.3 (48.8) N in the freeze-dried matrix group.
  
  
  CONCLUSIONS
  Enclosure of a tissue expander with human acellular dermal matrix untreated by gamma irradiation led to minimal inflammation and minimal evidence of fibrosis/capsule around the tissue expander compared with robust capsule formation around the tissue expander that was covered by a gamma-irradiated human acellular dermal matrix.
authors.affiliation: LifeCell Corporation, Bridgewater, NJ.
authors.forename: Maryellen
authors.initials: M
authors.lastname: Sandor
authors.affiliation: University of Maryland School of Medicine, Division of Plastic Surgery, Baltimore, MD.
authors.forename: Devinder
authors.initials: D
authors.lastname: Singh
authors.affiliation: University of Maryland School of Medicine, Division of Plastic Surgery, Baltimore, MD.
authors.forename: Ronald P
authors.initials: RP
authors.lastname: Silverman
authors.affiliation: LifeCell Corporation, Bridgewater, NJ.
authors.forename: Hui
authors.initials: H
authors.lastname: Xu
authors.affiliation: LifeCell Corporation, Bridgewater, NJ.
authors.forename: Patrick G
authors.initials: PG
authors.lastname: De Deyne
keywords: AlloDerm; acellular dermal matrix; animals; breast implants; foreign-body reaction; tissue expanders