title: Engineering patient-specific valves using stem cells generated from skin biopsy specimens.
abstract: BACKGROUND
  Pediatric patients requiring valve replacement will likely require reoperations due to a progressive deterioration of valve durability and limited repair and growth potential. To address these concerns, we sought to generate a biologically active pulmonary valve using patient-specific valvular cells and decellularized human pulmonary valves.
  
  
  METHODS
  We generated induced pluripotent stem cells (iPSCs) by reprogramming skin fibroblast cells. We then differentiated iPSCs to mesenchymal stem cells (iPCSs-MSCs) using culture conditions that favored an epithelial-to-mesenchymal transition. Next, decellularized human pulmonary heart valves were seeded with iPCS-MSCs using a combination of static and dynamic culture conditions and cultured up to 30 days.
  
  
  RESULTS
  The iPSCs-MSCs displayed cluster of differentiation CD105 and CD90 expression exceeding 90% after four passages and could differentiate into osteocytes, chondrocytes, and adipocytes (n = 4). Consistent with an MSC phenotype, iPSCs-MSCs lacked expression of CD45 and CD34. Compared with bone marrow MSCs, iPSCs-MSC proliferated more readily by twofold but maintained a gene expression profile exceeding 80% identical to bone marrow MSCs. In repopulated pulmonary valves compared with decellularized pulmonary valves, immunohistochemistry demonstrated increased cellularity, α-smooth muscle actin expression, and increased presence of extracellular matrix components, such as proteoglycans and glycosaminoglycans, suggesting sustained cell function and maturation.
  
  
  CONCLUSIONS
  Our results demonstrate the feasibility of constructing a biologically active human pulmonary valve using a sustainable and proliferative cell source. The bioactive pulmonary valve is expected to have advantages over existing valvular replacements, which will require further validation.
authors.affiliation: Division of Cardiac Surgery, University of Maryland Medical School, Baltimore, Maryland.
authors.forename: David L
authors.initials: DL
authors.lastname: Simpson
authors.affiliation: Division of Cardiac Surgery, University of Maryland Medical School, Baltimore, Maryland.
authors.forename: Brody
authors.initials: B
authors.lastname: Wehman
authors.affiliation: Developmental Biology Program, iPS and Human Stem Cell Core Facility, Children's Memorial Research Center, Northwestern University, Feinberg School of Medicine, Chicago, Illinois.
authors.forename: Yekaterina
authors.initials: Y
authors.lastname: Galat
authors.affiliation: Division of Cardiac Surgery, University of Maryland Medical School, Baltimore, Maryland.
authors.forename: Sudhish
authors.initials: S
authors.lastname: Sharma
authors.affiliation: Division of Cardiac Surgery, University of Maryland Medical School, Baltimore, Maryland.
authors.forename: Rachana
authors.initials: R
authors.lastname: Mishra
authors.affiliation: Developmental Biology Program, iPS and Human Stem Cell Core Facility, Children's Memorial Research Center, Northwestern University, Feinberg School of Medicine, Chicago, Illinois.
authors.forename: Vasiliy
authors.initials: V
authors.lastname: Galat
authors.affiliation: Division of Cardiac Surgery, University of Maryland Medical School, Baltimore, Maryland. Electronic address: skaushal@smail.umaryland.edu.
authors.forename: Sunjay
authors.initials: S
authors.lastname: Kaushal
mesh_terms: D001706:Biopsy; D002454:Cell Differentiation; D002478:Cells, Cultured; D006801:Humans; D011664:Pulmonary Valve / Q000166:cytology / Q000601:surgery*; D012867:Skin / Q000166:cytology* / Q000473:pathology; D033581:Stem Cell Transplantation; D023822:Tissue Engineering / Q000379:methods*