title: In vitro hypertrophy and calcification of human fracture haematoma-derived cells in chondrogenic differentiation.
abstract: OBJECTIVE
  The haematoma at a fracture site plays an important role in fracture healing. Previously, we demonstrated that a fracture haematoma contains multilineage mesenchymal progenitor cells. We postulated that the haematoma provided a source of chondrogenic cells for endochondral ossification during fracture healing and preservation of the cells contributed to biological fracture healing. In this study, we investigated whether haematoma-derived cells (HCs) could differentiate into hypertrophic chondrocytes and finally induce calcification of the extracellular matrix in vitro.
  
  
  METHODS
  Fracture haematomas were obtained from four patients. HCs were cultured for five weeks under conditions that induce chondrogenic differentiation, followed by two weeks of hypertrophic induction using a pellet culture system. The pellets were analysed histologically and immunohistochemically. The gene expression levels of chondrogenic, hypertrophic, osteogenic, and angiogenic markers were measured by real-time PCR.
  
  
  RESULTS
  The histological and immunohistochemical analyses revealed that HCs differentiated into chondrocytes and hypertrophic chondrocytes, followed by calcification of the extracellular matrix. This sequential differentiation was also reflected in the gene expression profiles. After chondrogenic induction, expression of osteogenic and angiogenic markers was not significantly upregulated. However, the expression of these markers was significantly upregulated following hypertrophic induction. These in vitro observations mimicked the process of endochondral ossification during fracture healing.
  
  
  CONCLUSIONS
  Our results suggest that the fracture haematoma may offer a source of cells with chondrogenic potential that play key roles in endochondral ossification during fracture healing. These findings support the opinion that the haematoma should be preserved for biological fracture healing.
authors: Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, 650-0017, Japan.
authors: Takaaki
authors: T
authors: Koga
authors: Takahiro
authors: T
authors: Niikura
authors: Sang Yang
authors: SY
authors: Lee
authors: Yoshihiro
authors: Y
authors: Dogaki
authors: Etsuko
authors: E
authors: Okumachi
authors: Kotaro
authors: K
authors: Nishida
authors: Ryosuke
authors: R
authors: Kuroda
authors: Masahiro
authors: M
authors: Kurosaka
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D002113:Calcification, Physiologic; D002454:Cell Differentiation; D049108:Cell Enlargement; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology* / Q000378:metabolism; D020219:Chondrogenesis / Q000502:physiology*; D005109:Extracellular Matrix / Q000378:metabolism; D017102:Fracture Healing / Q000502:physiology*; D050723:Fractures, Bone / Q000150:complications* / Q000473:pathology; D015870:Gene Expression; D006406:Hematoma / Q000150:complications* / Q000473:pathology; D006801:Humans; D008875:Middle Aged; D055815:Young Adult
chemical_list: D015415:Biomarkers