title: A First Step in De Novo Synthesis of a Living Pulp Tissue Replacement Using Dental Pulp MSCs and Tissue Growth Factors, Encapsulated within a Bioinspired Alginate Hydrogel.
abstract: BACKGROUND
  A living, self-supporting pulp tissue replacement in vitro and for transplantation is an attractive yet unmet bioengineering challenge. Our aim is to create 3-dimensional alginate-based microenvironments that replicate the shape of gutta-percha and comprise key elements for the proliferation of progenitor cells and the release of growth factors.
  
  
  METHODS
  An RGD-bearing alginate framework was used to encapsulate dental pulp stem cells and human umbilical vein endothelial cells in a ratio of 1:1. The alginate hydrogel also retained and delivered 2 key growth factors, vascular endothelial growth factor-121 and fibroblast growth factor, in a sufficient amount to induce proliferation. A method was then devised to replicate the shape of gutta-percha using RGD alginate within a custom-made mold of thermoresponsive N-isopropylacrylamide. Plugs of alginate containing different permutations of growth factor-based encapsulates were tested and evaluated for viability, proliferation, and release kinetics between 1 and 14 days.
  
  
  RESULTS
  According to scanning electron microscopic and confocal microscopic observations, the encapsulated human endothelial cells and dental pulp stem cell distribution were frequent and extensive throughout the length of the construct. There were also high levels of viability in all test environments. Furthermore, cell proliferation was higher in the growth factor-based groups. Growth factor release kinetics also showed significant differences between them. Interestingly, the combination of vascular endothelial growth factor and fibroblast growth factor synergize to significantly up-regulate cell proliferation.
  
  
  CONCLUSIONS
  RGD-alginate scaffolds can be fabricated into shapes to fill the pulp space by simple templating. The addition of dual growth factors to cocultures of stem cells within RGD-alginate scaffolds led to the creation of microenvironments that significantly enhance the proliferation of dental pulp stem cell/human umbilical vein endothelial cell combinations.
authors.affiliation: Oral Biosciences, Faculty of Dentistry, The University of Hong Kong Hospital, Sai Ying Pun, Hong Kong.
authors.forename: Manasi
authors.initials: M
authors.lastname: Bhoj
authors.affiliation: Comprehensive Dental Care, Faculty of Dentistry, The University of Hong Kong Hospital, Sai Ying Pun, Hong Kong. Electronic address: zhangcf@hku.hk.
authors.forename: Chengfei
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Oral Biosciences, Faculty of Dentistry, The University of Hong Kong Hospital, Sai Ying Pun, Hong Kong. Electronic address: dwgreen@hku.hk.
authors.forename: David W
authors.initials: DW
authors.lastname: Green
mesh_terms: D000464:Alginates; D018929:Cell Culture Techniques; D049109:Cell Proliferation; D003782:Dental Pulp / Q000166:cytology*; D005346:Fibroblast Growth Factors / Q000008:administration & dosage*; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D023822:Tissue Engineering / Q000379:methods*; D054457:Tissue Scaffolds; D042442:Vascular Endothelial Growth Factors / Q000008:administration & dosage*
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D042442:Vascular Endothelial Growth Factors; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D005346:Fibroblast Growth Factors; D020723:Glucuronic Acid
keywords: Dental pulp stem cells; RGD alginate; fibroblastic growth factor; human umbilical vein endothelial cells; vascular endothelial growth factor