title: Histological evolution of chronic wounds under negative pressure therapy.
abstract: BACKGROUND
  Negative pressure wound therapy (NPT) has achieved widespread success in the treatment of difficult wounds. However, its effects are but partially explored, and investigations mostly concentrated at the wound-dressing interface; a detailed histological description of the evolution of wounds under NPT is still lacking.
  
  
  METHODS
  Subsequent punch biopsies of NPT-treated chronic wounds of human patients were analysed. Phenomena occurring in wounds were quantified by analysis of proliferating cells nuclear antigen (PCNA) (proliferating nuclei), CD31 (blood vessels), CD68p (macrophages) and CD45 (lymphocytes) stained slides.
  
  
  RESULTS
  Three layers were identified in day-0 wounds. Over time, under NPT, the layers behaved differently: the most superficial (1.5 mm) developed granulation tissue, constant in thickness, with high proliferation index, increased in blood vessels density and developed acute inflammation. Instead, the two deeper layers decreased in proliferation rate, maintained vessels density unchanged, were cleared of chronic inflammation and oedema and underwent progression towards stable tissue.
  
  
  CONCLUSIONS
  Indeed, while most research has focused on induction of superficial granulation tissue by NPT, deeper layers appear to be also affected, with relieving of chronic inflammation and tissue stabilisation. This may be an important and under-appreciated effect, playing a role in the known positive outcomes of NPT, such as better graft-taking rates.
authors: Institute of Plastic Surgery, University of Padova, Padova, Italy.
authors: Franco
authors: F
authors: Bassetto
authors: Luca
authors: L
authors: Lancerotto
authors: Roberto
authors: R
authors: Salmaso
authors: Laura
authors: L
authors: Pandis
authors: Giorgio
authors: G
authors: Pajardi
authors: Mauro
authors: M
authors: Schiavon
authors: Cesare
authors: C
authors: Tiengo
authors: Vincenzo
authors: V
authors: Vindigni
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001707:Biopsy, Needle; D002908:Chronic Disease; D005260:Female; D005500:Follow-Up Studies; D006097:Granulation Tissue / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D007871:Leg Ulcer / Q000473:pathology* / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D054843:Negative-Pressure Wound Therapy / Q000379:methods*; D013997:Time Factors; D016896:Treatment Outcome; D014945:Wound Healing / Q000502:physiology*