TY - JOUR
T1 - In Vitro Assessment of Fluorine Nanoemulsion-Labeled Hyaluronan-Based Hydrogels for Precise Intrathecal Transplantation of Glial-Restricted Precursors
AU - Piejko, Marcin
AU - Walczak, Piotr
AU - Li, Xiaowei
AU - Bulte, Jeff W.M.
AU - Janowski, Miroslaw
N1 - Publisher Copyright:
© 2019, World Molecular Imaging Society.
PY - 2019/12/1
Y1 - 2019/12/1
N2 - Purpose: We studied the feasibility of labeling hydrogel scaffolds with a fluorine nanoemulsion for 19F- magnetic resonance imaging (MRI) to enable non-invasive visualization of their precise placement and potential degradation. Procedure: Hyaluronan-based hydrogels (activated hyaluronan, HA) with increasing concentrations of fluorine nanoemulsion (V-sense) were prepared to measure the gelation time and oscillatory stress at 1 h and 7 days after the beginning of gelation. All biomechanical measurements were conducted with an ARES 2 rheometer. Diffusion of fluorine from the hydrogel: Three hydrogels in various Vs to HA volumetric ratios (1:50, 1:10, and 1:5) were prepared in duplicate. Hydrogels were incubated at 37 °C. To induce diffusion, three hydrogels were agitated at 1000 rpm. 1H and 19F MRI scans were acquired at 1, 3, 7 days and 2 months after gel preparation on a Bruker Ascend 750 scanner. To quantify fluorine content, scans were analyzed using Voxel Tracker 2.0. Assessment of cell viability in vitro and in vivo: Luciferase-positive mouse glial-restricted progenitors (GRPs) were embedded in 0:1, 1:50, 1:10, and 1:5 Vs:HA mixtures (final cell concentration =1 × 107/ml). For the in vitro assay, mixtures were placed in 96-wells plate in triplicate and bioluminescence was measured after 1, 3, 7, 14, 21, and 28 days. For in vivo experiments, Vs/HA mixtures containing GRPs were injected subcutaneously in SCID mice and BLI was acquired at 1, 3, 7, and 14 days post-injection. Results: Mixing of V-sense at increasing ratios of 1:50, 1:10, and 1:5 v/v of fluorine/activated hyaluronan (HA) hydrogel gradually elongated the gelation time from 194 s for non-fluorinated controls to 304 s for 1:5 V-sense:HA hydrogels, while their elastic properties slightly decreased. There was no release of V-sense from hydrogels maintained in stationary conditions over 2 months. The addition of V-sense positively affected in vitro survival of scaffolded GRPs in a dose-dependent manner. Conclusions: These results show that hydrogel fluorination does not impair its beneficial properties for scaffolded cells, which may be used to visualize scaffolded GRP transplants with 19F MRI.
AB - Purpose: We studied the feasibility of labeling hydrogel scaffolds with a fluorine nanoemulsion for 19F- magnetic resonance imaging (MRI) to enable non-invasive visualization of their precise placement and potential degradation. Procedure: Hyaluronan-based hydrogels (activated hyaluronan, HA) with increasing concentrations of fluorine nanoemulsion (V-sense) were prepared to measure the gelation time and oscillatory stress at 1 h and 7 days after the beginning of gelation. All biomechanical measurements were conducted with an ARES 2 rheometer. Diffusion of fluorine from the hydrogel: Three hydrogels in various Vs to HA volumetric ratios (1:50, 1:10, and 1:5) were prepared in duplicate. Hydrogels were incubated at 37 °C. To induce diffusion, three hydrogels were agitated at 1000 rpm. 1H and 19F MRI scans were acquired at 1, 3, 7 days and 2 months after gel preparation on a Bruker Ascend 750 scanner. To quantify fluorine content, scans were analyzed using Voxel Tracker 2.0. Assessment of cell viability in vitro and in vivo: Luciferase-positive mouse glial-restricted progenitors (GRPs) were embedded in 0:1, 1:50, 1:10, and 1:5 Vs:HA mixtures (final cell concentration =1 × 107/ml). For the in vitro assay, mixtures were placed in 96-wells plate in triplicate and bioluminescence was measured after 1, 3, 7, 14, 21, and 28 days. For in vivo experiments, Vs/HA mixtures containing GRPs were injected subcutaneously in SCID mice and BLI was acquired at 1, 3, 7, and 14 days post-injection. Results: Mixing of V-sense at increasing ratios of 1:50, 1:10, and 1:5 v/v of fluorine/activated hyaluronan (HA) hydrogel gradually elongated the gelation time from 194 s for non-fluorinated controls to 304 s for 1:5 V-sense:HA hydrogels, while their elastic properties slightly decreased. There was no release of V-sense from hydrogels maintained in stationary conditions over 2 months. The addition of V-sense positively affected in vitro survival of scaffolded GRPs in a dose-dependent manner. Conclusions: These results show that hydrogel fluorination does not impair its beneficial properties for scaffolded cells, which may be used to visualize scaffolded GRP transplants with 19F MRI.
KW - Fluorine
KW - Glial-restricted precursors
KW - Hydrogel
KW - MRI
KW - Scaffold
UR - http://www.scopus.com/inward/record.url?scp=85062781954&partnerID=8YFLogxK
U2 - 10.1007/s11307-019-01341-6
DO - 10.1007/s11307-019-01341-6
M3 - Article
C2 - 30850968
AN - SCOPUS:85062781954
SN - 1536-1632
VL - 21
SP - 1071
EP - 1078
JO - Molecular Imaging and Biology
JF - Molecular Imaging and Biology
IS - 6
ER -