title: In vivo bioluminescence imaging for viable human neural stem cells incorporated within in situ gelatin hydrogels.
abstract: BACKGROUND
  Three-dimensional (3D) hydrogel-based stem cell therapies contribute to enhanced therapeutic efficacy in treating diseases, and determining the optimal mechanical strength of the hydrogel in vivo is important for therapeutic success. We evaluated the proliferation of human neural stem cells incorporated within in situ-forming hydrogels and compared the effect of hydrogels with different elastic properties in cell/hydrogel-xenografted mice.
  
  
  METHODS
  The gelatin-polyethylene glycol-tyramine (GPT) hydrogel was fabricated through enzyme-mediated cross-linking reaction using horseradish peroxidase (HRP) and hydrogen peroxide (H2O2).
  
  
  RESULTS
  The F3-effluc encapsulated within a soft 1,800 pascal (Pa) hydrogel and stiff 5,800 Pa hydrogel proliferated vigorously in a 24-well plate until day 8. In vitro and in vivo kinetics of luciferase activity showed a slow time-to-peak after D-luciferin administration in the stiff hydrogel. When in vivo proliferation of F3-effluc was observed up to day 21 in both the hydrogel group and cell-only group, F3-effluc within the soft hydrogel proliferated more vigorously, compared to the cells within the stiff hydrogel. Ki-67-specific immunostaining revealed highly proliferative F3-effluc with compactly distributed cell population inside the 1,800 Pa or 5,800 Pa hydrogel.
  
  
  CONCLUSIONS
  We examined the in vivo effectiveness of different elastic types of hydrogels encapsulating viable neural stem cells by successfully monitoring the proliferation of implanted stem cells incorporated within a 3D hydrogel scaffold.
authors.affiliation: Department of Nuclear Medicine, Seoul National University College of Medicine, 28 Yongon-Dong, Jongno-Gu, Seoul, 110-744, Republic of Korea, hdw6592@hanmail.net.
authors.forename: Do Won
authors.initials: DW
authors.lastname: Hwang
authors.forename: Kyung Min
authors.initials: KM
authors.lastname: Park
authors.forename: Hye-Kyung
authors.initials: HK
authors.lastname: Shim
authors.forename: Yeona
authors.initials: Y
authors.lastname: Jin
authors.forename: Hyun Jeong
authors.initials: HJ
authors.lastname: Oh
authors.forename: So Won
authors.initials: SW
authors.lastname: Oh
authors.forename: Song
authors.initials: S
authors.lastname: Lee
authors.forename: Hyewon
authors.initials: H
authors.lastname: Youn
authors.forename: Yoon Ki
authors.initials: YK
authors.lastname: Joung
authors.forename: Hong J
authors.initials: HJ
authors.lastname: Lee
authors.forename: Seung U
authors.initials: SU
authors.lastname: Kim
authors.forename: Ki Dong
authors.initials: KD
authors.lastname: Park
authors.forename: Dong Soo
authors.initials: DS
authors.lastname: Lee