title: A self-setting iPSMSC-alginate-calcium phosphate paste for bone tissue engineering.
abstract: OBJECTIVE
  Calcium phosphate cements (CPCs) are promising for dental and craniofacial repairs. The objectives of this study were to: (1) develop an injectable cell delivery system based on encapsulation of induced pluripotent stem cell-derived mesenchymal stem cells (iPSMSCs) in microbeads; (2) develop a novel tissue engineered construct by dispersing iPSMSC-microbeads in CPC to investigate bone regeneration in an animal model for the first time.
  
  
  METHODS
  iPSMSCs were pre-osteoinduced for 2 weeks (OS-iPSMSCs), or transduced with bone morphogenetic protein-2 (BMP2-iPSMSCs). Cells were encapsulated in fast-degradable alginate microbeads. Microbeads were mixed with CPC paste and filled into cranial defects in nude rats. Four groups were tested: (1) CPC-microbeads without cells (CPC control); (2) CPC-microbeads-iPSMSCs (CPC-iPSMSCs); (3) CPC-microbeads-OS-iPSMSCs (CPC-OS-iPSMSCs); (4) CPC-microbeads-BMP2-iPSMSCs (CPC-BMP2-iPSMSCs).
  
  
  RESULTS
  Cells maintained good viability inside microbeads after injection. The microbeads were able to release the cells which had more than 10-fold increase in live cell density from 1 to 14 days. The cells exhibited up-regulation of osteogenic markers and deposition of minerals. In vivo, new bone area fraction (mean±SD; n=5) for CPC-iPSMSCs group was (22.5±7.6)%. New bone area fractions were (38.9±18.4)% and (44.7±22.8)% for CPC-OS-iPSMSCs group and CPC-BMP2-iPSMSCs group, respectively, 2-3 times the (15.6±11.2)% in CPC control at 12 weeks (p<0.05). Cell-CPC constructs accelerated scaffold resorption, with CPC-BMP2-iPSMSCs having remaining scaffold material that was 7-fold less than CPC control.
  
  
  CONCLUSIONS
  Novel injectable CPC-microbead-cell constructs promoted bone regeneration, with OS-iPSMSCs and BMP2-iPSMSCs having 2-3 fold the new bone of CPC control. Cell delivery accelerated scaffold resorption, with CPC-BMP2-iPSMSC having remaining scaffold material that was 7-fold less than CPC control. Therefore, CPC-microbead-iPSMSC is a promising injectable material for orthopedic, dental and craniofacial bone regenerations.
authors.affiliation: Biomaterials & Tissue Engineering Division, Department of Endodontics, Prosthodontics and Operative Dentistry, University of Maryland Dental School, Baltimore, MD 21201, USA; State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan 610041, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Wang
authors.affiliation: Biomaterials & Tissue Engineering Division, Department of Endodontics, Prosthodontics and Operative Dentistry, University of Maryland Dental School, Baltimore, MD 21201, USA.
authors.forename: Yang
authors.initials: Y
authors.lastname: Song
authors.affiliation: Biomaterials & Tissue Engineering Division, Department of Endodontics, Prosthodontics and Operative Dentistry, University of Maryland Dental School, Baltimore, MD 21201, USA.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Weir
authors.affiliation: Biomaterials & Tissue Engineering Division, Department of Endodontics, Prosthodontics and Operative Dentistry, University of Maryland Dental School, Baltimore, MD 21201, USA.
authors.forename: Jinyu
authors.initials: J
authors.lastname: Sun
authors.affiliation: Biomaterials & Tissue Engineering Division, Department of Endodontics, Prosthodontics and Operative Dentistry, University of Maryland Dental School, Baltimore, MD 21201, USA; Department of Orthopaedic Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong 510515, China. Electronic address: lzhaonf@126.com.
authors.forename: Liang
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Biosystems and Biomaterials Division, National Institute of Standards & Technology, 100 Bureau Drive, Gaithersburg, MD, 20899, USA.
authors.forename: Carl G
authors.initials: CG
authors.lastname: Simon
authors.affiliation: Biomaterials & Tissue Engineering Division, Department of Endodontics, Prosthodontics and Operative Dentistry, University of Maryland Dental School, Baltimore, MD 21201, USA; Center for Stem Cell Biology and Regenerative Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, USA; University of Maryland Marlene and Stewart Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, MD 21201, USA; Mechanical Engineering Department, University of Maryland Baltimore County, Baltimore County, MD 21250, USA. Electronic address: hxu@umaryland.edu.
authors.forename: Hockin H K
authors.initials: HH
authors.lastname: Xu
mesh_terms: D000464:Alginates / Q000494:pharmacology*; D000818:Animals; D002130:Calcium Phosphates / Q000494:pharmacology*; D002454:Cell Differentiation; D049109:Cell Proliferation; D002470:Cell Survival; D018920:Coculture Techniques; D020723:Glucuronic Acid / Q000494:pharmacology; D006603:Hexuronic Acids / Q000494:pharmacology; D007150:Immunohistochemistry; D008297:Male; D045164:Mesenchymal Stem Cell Transplantation / Q000379:methods*; D059630:Mesenchymal Stem Cells / Q000187:drug effects*; D008819:Mice, Nude; D008863:Microspheres; D010012:Osteogenesis / Q000187:drug effects*; D051381:Rats; D011923:Rats, Nude; D012886:Skull / Q000601:surgery; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds
chemical_list: D000464:Alginates; D002130:Calcium Phosphates; D006603:Hexuronic Acids; D020723:Glucuronic Acid
keywords: Alginate microbeads; Animal studies; Bone tissue engineering; Calcium phosphate cement; Human induced pluripotent stem cells; Injectable