title: Flexor tendon tissue engineering: acellularization of human flexor tendons with preservation of biomechanical properties and biocompatibility.
abstract: OBJECTIVE
  Acellular human tendons are a candidate scaffold for tissue engineering flexor tendons of the hand. This study compared acellularization methods and their compatibility with allogeneic human cells.
  
  
  METHODS
  Human flexor tendons were pretreated with 0.1% ethylenediaminetetracetic acid (EDTA) for 4  h followed by 24  h treatments of 1% Triton X-100, 1% tri(n-butyl)phosphate, or 0.1% or 1% sodium dodecyl sulfate (SDS) in 0.1% EDTA. Outcomes were assessed histologically by hematoxylin and eosin and SYTO green fluorescent nucleic acid stains and biochemically by a QIAGEN DNeasy kit, Sircol collagen assay, and 1,9 dimethylmethylene blue glycosaminoglycan assay. Mechanical data were collected using a Materials Testing System to pull to failure tendons acellularized with 0.1% SDS. Acellularized tendons were re-seeded in a suspension of human dermal fibroblasts. Attachment of viable cells to acellularized tendon was assessed biochemically by a cell viability assay and histologically by a live/dead stain. Data are reported as mean±standard deviation.
  
  
  RESULTS
  Compared with the DNA content of fresh tendons (551±212  ng DNA/mg tendon), only SDS treatments significantly decreased DNA content (1% SDS [202.8±37.4  ng DNA/mg dry weight tendon]; 0.1% SDS [189±104  ng DNA/mg tendon]). These findings were confirmed by histology. There was no decrease in glycosaminoglycans or collagen following acellularization with SDS. There was no difference in the ultimate tensile stress (55.3±19.2 [fresh] vs. 51.5±6.9 [0.1% SDS] MPa). Re-seeded tendons demonstrated attachment of viable cells to the tendon surface using a viability assay and histology.
  
  
  CONCLUSIONS
  Human flexor tendons were acellularized with 0.1% SDS in 0.1% EDTA for 24  h with preservation of mechanical properties. Preservation of collagen and glycoaminoglycans and re-seeding with human cells suggest that this scaffold is biocompatible. This will provide a promising scaffold for future human flexor tendon tissue engineering studies to further assess biocompatibility through cell proliferation and in vivo studies.
authors.affiliation: Section of Plastic Surgery, VA Palo Alto Health Care System and the Division of Plastic Surgery, Stanford University Medical Center, Stanford, California 94305, USA.
authors.forename: Brian C
authors.initials: BC
authors.lastname: Pridgen
authors.forename: Colin Y L
authors.initials: CY
authors.lastname: Woon
authors.forename: Maxwell
authors.initials: M
authors.lastname: Kim
authors.forename: Johan
authors.initials: J
authors.lastname: Thorfinn
authors.forename: Derek
authors.initials: D
authors.lastname: Lindsey
authors.forename: Hung
authors.initials: H
authors.lastname: Pham
authors.forename: James
authors.initials: J
authors.lastname: Chang
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry*; D001696:Biomechanical Phenomena; D049109:Cell Proliferation; D002470:Cell Survival; D004247:DNA / Q000378:metabolism; D005347:Fibroblasts / Q000473:pathology; D006025:Glycosaminoglycans / Q000737:chemistry; D006801:Humans; D012867:Skin / Q000473:pathology; D013708:Tendon Injuries / Q000473:pathology*; D013710:Tendons / Q000473:pathology*; D013718:Tensile Strength; D023822:Tissue Engineering / Q000379:methods*
chemical_list: D001672:Biocompatible Materials; D006025:Glycosaminoglycans; D004247:DNA