title: A β-cyclodextrin, polyethyleneimine and silk fibroin hydrogel containing Centella asiatica extract and hydrocortisone acetate: releasing properties and in vivo efficacy for healing of pressure sores.
abstract: BACKGROUND
  Pressure sores are lesions caused by impaired blood flow. Conventional dressings can absorb exudates, but do not promote wound healing. A hydrogel composed of β-cyclodextrin (β-CD), polyethyleneimine (PEI) and silk fibroin (SF) was assessed for use in healing of pressure sores.
  
  
  METHODS
  The hydrogel was prepared by crosslinking β-CD-grafted PEI and SF using epichlorohydrin. The gel was then immersed in an aqueous solution of Centella asiatica extract (CAE) 0.7 mg/mL and/or hydrocortisone acetate (HCA) 0.5 mg/mL. The in vivo pressure sore-healing efficacy of the dry gel (with or without the drugs) was investigated in terms of the hyperplasia of epidermis and the number of neutrophils in the skin tissue.
  
  
  RESULTS
  The specific loading of CAE was 0.0091 g/g of dry gel. The percentage of CAE released at 24 h at pH 3.0, 5.0 and 7.4 was approximately 63.9%, 55.0% and 44.4%, respectively. This pH-dependent release is possibly due to the degree of gel swelling, which decreased with increasing pH. The specific loading of HCA was 0.0050 g/g dry gel, and the percentage release of HCA at 24 h was around 20% at all three pH points. It is likely that HCA release is independent of pH. HCA is a hydrophobic compound, and therefore the release of HCA is affected by the partitioning of HCA between the β-CD cavity and the bulk water phase, but not by the degree of swelling of the hydrogel. The pressure sores treated with the hydrogel healed in 6 days, compared with 10 days for controls.
  
  
  CONCLUSIONS
  In this study, a β-CD/PEI/SF hydrogel containing CAE and HCA reduced the healing time for pressure sores.
authors.affiliation: Division of Biotechnology and Bioengineering and Institute of Bioscience and Biotechnology, Kangwon National University, Kangwon-do, Korea.
authors.forename: M S
authors.initials: MS
authors.lastname: Lee
authors.forename: S R
authors.initials: SR
authors.lastname: Seo
authors.forename: J-C
authors.initials: JC
authors.lastname: Kim
mesh_terms: D000818:Animals; D028041:Centella; D005349:Fibroins / Q000627:therapeutic use*; D006854:Hydrocortisone / Q000031:analogs & derivatives* / Q000627:therapeutic use; D020100:Hydrogels / Q000138:chemical synthesis / Q000627:therapeutic use*; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D010936:Plant Extracts; D011094:Polyethyleneimine / Q000627:therapeutic use*; D003668:Pressure Ulcer / Q000188:drug therapy*; D047011:Silk; D012867:Skin / Q000187:drug effects; D014315:Triterpenes / Q000627:therapeutic use*; D014945:Wound Healing / Q000187:drug effects; D047392:beta-Cyclodextrins / Q000627:therapeutic use*
chemical_list: C526146:Centella asiatica extract; D020100:Hydrogels; D010936:Plant Extracts; D047011:Silk; D014315:Triterpenes; D047392:beta-Cyclodextrins; C021650:hydrocortisone acetate; D011094:Polyethyleneimine; D005349:Fibroins; D006854:Hydrocortisone