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Fig. 1 | Stem Cell Research & Therapy

Fig. 1

From: Exogenous marker-engineered mesenchymal stem cells detect cancer and metastases in a simple blood assay

Fig. 1

Humanized Gaussia luciferase (hGluc) is secreted in vitro and is stable in blood. a Mesenchymal stem cells expressing humanized Gaussia luciferase (hGluc-MSC) and native MSCs (N-MSCs) were seeded onto 96-well plates. Twenty-four hours later, cell-free conditioned medium (CM) was harvested. The hGluc substrate coelenterazine (CTZ) was added with a final concentration of 20 μM. hGluc activity was measured immediately by using a plate reader (absorbance at wavelengths of 300-700 nm, exposure time = 2 s). b Serial dilution of hGluc-MSC CM was performed in PBS, and CTZ was added at a final concentration of 20 μM. hGluc activity was measured with an IVIS Lumina (exposure time = 0.5 s). Color scale: minimum = 6.64×108, maximum = 8.93×109. c CM of hGluc-MSCs was harvested and incubated with human serum for 10 minutes and 2, 8, or 24 hours at 37 °C. A final concentration of 20 μM of CTZ was added, and hGluc activity was measured immediately (exposure time = 2 s). hGluc activity was detectable in 100 % serum. ****P < 0.0001. Error bar: mean ± standard deviation. A.U. arbitrary units, PBS phosphate-buffered saline

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