title: Benefits of biphasic calcium phosphate hybrid scaffold-driven osteogenic differentiation of mesenchymal stem cells through upregulated leptin receptor expression.
abstract: BACKGROUND
  The use of mesenchymal stem cells (MSCs) and coralline hydroxyapatite (HA) or biphasic calcium phosphate (BCP) as a bone substitute for posterolateral spinal fusion has been reported. However, the genes and molecular signals by which MSCs interact with their surrounding environment require further elucidation.
  
  
  METHODS
  MSCs were harvested from bone grafting patients and identified by flow cytometry. A composite scaffold was developed using poly(lactide-co-glycolide) (PLGA) copolymer, coralline HA, BCP, and collagen as a carrier matrix for MSCs. The gene expression profiles of MSCs cultured in the scaffolds were measured by microarrays. The alkaline phosphatase (ALP) activity of the MSCs was assessed, and the expression of osteogenic genes and proteins was determined by quantitative polymerase chain reaction (Q-PCR) and Western blotting. Furthermore, we cultured rabbit MSCs in BCP or coralline HA hybrid scaffolds and transplanted these mixtures into rabbits for spinal fusion. We investigated the differences between BCP and coralline HA hybrid scaffolds by dual-energy X-ray absorptiometry (DEXA) and computed tomography (CT).
  
  
  RESULTS
  Tested in vitro, the cells were negative for hematopoietic cell markers and positive for MSC markers. There was higher expression of 80 genes and lower of 101 genes of MSCs cultured in BCP hybrid scaffolds. Some of these genes have been shown to play a role in osteogenesis of MSCs. In addition, MSCs cultured in BCP hybrid scaffolds produced more messenger RNA (mRNA) for osteopontin, osteocalcin, Runx2, and leptin receptor (leptin-R) than those cultured in coralline HA hybrid scaffolds. Western blotting showed more Runx2 and leptin-R protein expression in BCP hybrid scaffolds. For in vivo results, 3D reconstructed CT images showed continuous bone bridges and fusion mass incorporated with the transverse processes. Bone mineral content (BMC) values were higher in the BCP hybrid scaffold group than in the coralline HA hybrid scaffold group.
  
  
  CONCLUSIONS
  The BCP hybrid scaffold for osteogenesis of MSCs is better than the coralline HA hybrid scaffold by upregulating expression of leptin-R. This was consistent with in vivo data, which indicated that BCP hybrid scaffolds induced more bone formation in a spinal fusion model.
authors.affiliation: Department of Orthopaedics, Chang Gung Memorial Hospital, No. 5, Fu-Hsing Street 333, Kweishan, Taoyuan, Taiwan. niuchien@adm.cgmh.org.tw.|College of Medicine, Chang Gung University, Taoyuan, Taiwan. niuchien@adm.cgmh.org.tw.
authors.forename: Chi-Chien
authors.initials: CC
authors.lastname: Niu
authors.affiliation: Department of Orthopaedics, Chang Gung Memorial Hospital, No. 5, Fu-Hsing Street 333, Kweishan, Taoyuan, Taiwan. lss1192001@yahoo.com.tw.
authors.forename: Song-Shu
authors.initials: SS
authors.lastname: Lin
authors.affiliation: Department of Orthopaedics, Chang Gung Memorial Hospital, No. 5, Fu-Hsing Street 333, Kweishan, Taoyuan, Taiwan. chenwenj@adm.cgmh.org.tw.|College of Medicine, Chang Gung University, Taoyuan, Taiwan. chenwenj@adm.cgmh.org.tw.
authors.forename: Wen-Jer
authors.initials: WJ
authors.lastname: Chen
authors.affiliation: Department of Mechanical Engineering, Chang Gung University, Taoyuan, Taiwan. shihjung@mail.cgu.edu.tw.
authors.forename: Shih-Jung
authors.initials: SJ
authors.lastname: Liu
authors.affiliation: Department of Orthopaedics, Chang Gung Memorial Hospital, No. 5, Fu-Hsing Street 333, Kweishan, Taoyuan, Taiwan. lhchen2132@adm.cgmh.org.tw.|College of Medicine, Chang Gung University, Taoyuan, Taiwan. lhchen2132@adm.cgmh.org.tw.
authors.forename: Lih-Huei
authors.initials: LH
authors.lastname: Chen
authors.affiliation: Department of Orthopaedics, Chang Gung Memorial Hospital, No. 5, Fu-Hsing Street 333, Kweishan, Taoyuan, Taiwan. ycyfl@yahoo.com.tw.
authors.forename: Chuen-Yung
authors.initials: CY
authors.lastname: Yang
authors.affiliation: Department of Radiology, Chang Gung Memorial Hospital, Taoyuan, Taiwan. cjwang@cgmh.org.tw.
authors.forename: Chao-Jan
authors.initials: CJ
authors.lastname: Wang
authors.affiliation: Department of Orthopaedics, Chang Gung Memorial Hospital, No. 5, Fu-Hsing Street 333, Kweishan, Taoyuan, Taiwan. lry51524@adm.cgmh.org.tw.|College of Medicine, Chang Gung University, Taoyuan, Taiwan. lry51524@adm.cgmh.org.tw.
authors.forename: Li-Jen
authors.initials: LJ
authors.lastname: Yuan
authors.affiliation: Department of Orthopaedics, Chang Gung Memorial Hospital, No. 5, Fu-Hsing Street 333, Kweishan, Taoyuan, Taiwan. bluejays1204@gmail.com.
authors.forename: Po-Han
authors.initials: PH
authors.lastname: Chen
authors.affiliation: Department of Radiology, Chang Gung Memorial Hospital, Taoyuan, Taiwan. chenged@cgmh.org.tw.
authors.forename: Hsiao-Yang
authors.initials: HY
authors.lastname: Cheng
mesh_terms: D000818:Animals; D018786:Bone Substitutes / Q000008:administration & dosage; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D006801:Humans; D006882:Hydroxyapatites / Q000008:administration & dosage*; D045164:Mesenchymal Stem Cell Transplantation / Q000379:methods; D059630:Mesenchymal Stem Cells / Q000378:metabolism*; D010012:Osteogenesis / Q000187:drug effects / Q000502:physiology*; D019736:Prostheses and Implants; D011817:Rabbits; D054411:Receptors, Leptin / Q000096:biosynthesis*; D054457:Tissue Scaffolds; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
chemical_list: D018786:Bone Substitutes; D006882:Hydroxyapatites; D054411:Receptors, Leptin; C074950:hydroxyapatite-beta tricalcium phosphate