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. Author manuscript; available in PMC: 2019 Feb 1.
Published in final edited form as: Curr Osteoporos Rep. 2018 Feb;16(1):32–41. doi: 10.1007/s11914-018-0414-3

Table 1.

Summary of selective in vivo tracer studies on the LCS’s cut-off size and tracer diffusivity

Tracer MW
(kDa)		 Dia
(nm)		 Animal/circulation time/sample
preparation [reference]		 Penetration
to LCS		 Diffusivity
DLCS (µm2/s)		 Characteristic
time tc (sec)#
Sodium fluorescein 0.4 0.9 4–6-month-old B6 female mice/20 min/ intact bone [36] Yes 330 ± 60 68
Sodium fluorescein 0.4 0.9 3–5-month-old B6 mice/tail vein/30 min/in situ imaging of intact bone [33] Yes 294.8 ± 45.8 77
Sodium fluorescein 0.4 0.9 3–4-month-old B6 male mice/tail vein/30 min/in situ imaging of intact bone [34] Yes 272 83
Sodium fluorescein 0.4 0.9 12–13-month-old B6 male mice/tail vein/30 min/in situ imaging of intact bone [35] Yes 302 ± 72 75
Reactive red 1.47 1.6 2–3-month-old Sprague-Dawley male rats/jugular vein/5 min/decalcified sections [37] yes -
Micro-peroxidase 1.86 1.7 2–3-month-old Sprague-Dawley male rats/jugular vein/5 min/decalcified sections [37] yes -
Dextran 3 2.8* 3–5-month-old B6 mice/ tail vein/1.5h/in situ imaging of intact bone [33] yes 128.0 ± 31.7 176
Dextran 3 2.8* Skeletal matured Sprague-Dawley female rats/tail vein/1–2min/plastic embedded sections [38] yes -
Dextran 10 4.6* 3–5-month-old B6 mice/ tail vein/3h/in situ imaging of intact bone [33] Yes (no load) 0** -
Dextran 10 4.6* Skeletal matured Sprague-Dawley female rats/tail vein/1–2min/plastic embedded sections [38] No (no load) Yes (3000 µε) -
parvalbumin 12.3 2.6 3–5-month-old B6 mice/tail vein/1.5h/in situ imaging of intact bone [33] yes 157.4 ± 87.7 143
parvalbumin 12.3 2.6 12–13-month-old B6 male mice/tail vein/2h/in situ imaging of intact bone [35] yes 200 ± 55 113
Horseradish peroxidase 40 6 2–3-month-old Sprague-Dawley male rats/jugular vein/5 min/decalcified sections [37] yes -
ovalbumin 43 6 3–5-month-old B6 mice/tail vein/7h/in situ imaging of intact bone [33] yes 65.3 ± 20.7 346
albumin 67 7 5-month-old Sprague-Dawley female rats/jugular vein/4–5min/plastic sections [39] Yes (no load) Yes (500 µε) -
dextran 70 12* Skeletal matured Sprague-Dawley female rats/tail vein/1–2min/plastic embedded sections [38] No (no load) No (3000 µε)) -
ferritin 440 12 2–3-month-old Sprague-Dawley male rats/jugular vein/5 min/decalcified sections [37] No -

Notes:

#

Characteristic time was calculated as tc = R2/D for molecular diffusion over a representative osteon of radius R = 150 µm;

**

dextran 10 kDa was perfused in bone but no fluorescence recovery was observed during the ~5 min imaging period after photobleaching.