title: Induced periosteum a complex cellular scaffold for the treatment of large bone defects.
abstract: OBJECTIVE
  Surgically induced periosteal membrane holds great potential for the treatment of large bone defects representing a simple alternative to combinations of exogenous stem cells, scaffolds and growth factors. The purpose of this study was to explore the biological basis for this novel regenerative medicine strategy in man.
  
  
  METHODS
  Eight patients with critical size defects were treated with the induced membrane (IM) technique. After membrane formation 1cm(2) biopsy was taken together with matched, healthy diaphyseal periosteum (P) for comparative analysis. Morphological characteristics, cell composition and growth factor expression were compared. Functional and molecular evaluation of mesenchymal stromal cell (MSC) activity was performed.
  
  
  RESULTS
  Both tissues shared similar morphology although IM was significantly thicker than P (p=0.032). The frequency of lymphocytes, pericytes (CD45(-)CD34(-)CD146(+)) and cells expressing markers consistent with bone marrow MSCs (CD45(-/low)CD271(bright)) were 31. 3 and 15.5-fold higher respectively in IM (all p=0.043). IM contained 3-fold more cells per gramme of tissue with a similar proportion of endothelial cells (CD45(-)CD31(+)). Expressed bone morphogenic protein 2, vascular endothelial growth factor and stromal derived factor 1 (SDF-1) are key tissue regeneration mediators. Adherent expanded cells from both tissues had molecular profiles similar to bone marrow MSCs but cells from IM expressed greater than 2 fold relative abundance of SDF-1transcript compared to P (p=0.043).
  
  
  CONCLUSIONS
  The IM is a thick, vascularised structure that resembles periosteum with a cellular composition and molecular profile facilitating large defect repair and therefore may be described as an "induced-periosteum". This tissue offers a powerful example of in situ tissue engineering.
authors: Leeds Institute of Rheumatic and Musculoskeletal Medicine, University of Leeds, LS9 7TF, UK; Leeds NIHR Biomedical Research Unit, Leeds Institute of Molecular Medicine, Beckett Street, Leeds, LS9 7TF, UK.
authors: Richard J
authors: RJ
authors: Cuthbert
authors: Sarah M
authors: SM
authors: Churchman
authors: Hiang B
authors: HB
authors: Tan
authors: Dennis
authors: D
authors: McGonagle
authors: Elena
authors: E
authors: Jones
authors: Peter V
authors: PV
authors: Giannoudis
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001847:Bone Diseases / Q000473:pathology / Q000628:therapy*; D002454:Cell Differentiation; D003114:Colony-Forming Units Assay; D016207:Cytokines / Q000378:metabolism; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D044085:Microfluidics; D008875:Middle Aged; D010521:Periosteum / Q000166:cytology* / Q000378:metabolism; D054457:Tissue Scaffolds / Q000737:chemistry*; D055815:Young Adult
chemical_list: D016207:Cytokines
keywords: Bone regeneration; Induced membrane; Induced-periosteum; MSC; Osteoprogenitor cells