title: Scaffold-free cell sheet injection results in bone formation.
abstract: We previously reported a new cell transplantation method in which mesenchymal stem cells (MSCs) were cultured as cell sheets. The cultured MSC sheets showed high alkaline phosphatase (ALP) activities and osteocalcin (OC) contents. In the present study, we transplanted such sheets by injection to assess whether the injectable MSC sheets could form bone tissue at subcutaneous sites. At 4 weeks after the subcutaneous injection, the injected areas showed hard mass formation. Each mass consisted of newly formed bone, as evaluated by radiographic, histological and gene expression analyses as well as three-dimensional computed tomography (3D-CT). Histological analyses revealed extracellular bone matrix together with osteocytes and active osteoblasts. Real-time PCR analyses showed high ALP and OC mRNA expressions. We also injected the cell sheets into dead bone to determine whether the lost osteogenic potential could be rescued, and histological analyses revealed that the injected cell sheets supplied osteogenic potential to the dead bone. The present study clearly indicates that osteogenic MSC sheets can be transplanted via injection through a needle and that bone formation results in the injected areas. Owing to its usage of a needle for fabrication of in vivo bone tissue, this injection method can be applied as a minimally invasive approach for hard tissue reconstruction.
authors.affiliation: Department of Public Health, Health Management and Policy, Nara Medical University School of Medicine, Kashihara, Nara 634-8521, Japan. makahane@naramed-u.ac.jp
authors.forename: Manabu
authors.initials: M
authors.lastname: Akahane
authors.forename: Hideki
authors.initials: H
authors.lastname: Shigematsu
authors.forename: Mika
authors.initials: M
authors.lastname: Tadokoro
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Ueha
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Yasuaki
authors.initials: Y
authors.lastname: Tohma
authors.forename: Akira
authors.initials: A
authors.lastname: Kido
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Imamura
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Tanaka
mesh_terms: D000469:Alkaline Phosphatase / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001842:Bone and Bones / Q000166:cytology / Q000000981:diagnostic imaging / Q000378:metabolism; D007279:Injections, Subcutaneous; D045164:Mesenchymal Stem Cell Transplantation / Q000379:methods; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D015675:Osteocalcin / Q000235:genetics / Q000378:metabolism; D010012:Osteogenesis / Q000502:physiology*; D051381:Rats; D011916:Rats, Inbred F344; D044968:Regenerative Medicine / Q000379:methods; D054457:Tissue Scaffolds; D014057:Tomography, X-Ray Computed
chemical_list: D015675:Osteocalcin; D000469:Alkaline Phosphatase