Methodological differences account for inconsistencies in reported free VEGF concentrations in pregnant rats

Tracey L. Weissgerber; Andrea McConico; Bruce E. Knudsen; Kim A. Butters; Suzanne R. Hayman; Wendy M. White; Natasa Milic; Virginia M. Miller; Vesna D. Garovic

doi:10.1152/ajpregu.00544.2013

Methodological differences account for inconsistencies in reported free VEGF concentrations in pregnant rats

Tracey L. Weissgerber, Andrea McConico, Bruce E. Knudsen, Kim A. Butters, Suzanne R. Hayman, Wendy M. White, Natasa Milic, Virginia M. Miller, Vesna D. Garovic

Research output: Contribution to journal › Article › peer-review

6 Scopus citations

Abstract

Free vascular endothelial growth factor (VEGF) is undetectable in plasma during human pregnancy. However, studies examining pregnant rats have reported both low (8-29 pg/ml) and high (527-1,030 pg/ml) free VEGF. These discrepancies cast uncertainty over the use of rat models to study angiogenic factors in pregnancy and preeclampsia. This study investigates methodological factors that may explain these discrepancies. Plasma VEGF in nonpregnant, day 7 pregnant, and day 19 pregnant rats was measured using rat and mouse ELISAs (R&D Systems). The rat ELISA detected VEGF in plasma from nonpregnant rats but not in plasma from day 19 pregnant rats. The mouse ELISA detected higher VEGF concentrations than the rat ELISA in every sample tested. This discrepancy was greater in day 19 pregnant rats (median: 2,273 vs. 0 pg/ml) than in nonpregnant (97 vs. 20 pg/ml) and day 7 pregnant (66 vs. 2 pg/ml) rats. Recovery of recombinant rat VEGF (rrVEGF) spiked into plasma from nonpregnant and day 7 pregnant rats was high for the rat ELISA (82-105%) but low for the mouse ELISA (17-22%). The rat ELISA did not recover rrVEGF in plasma from day 19 pregnant rats, suggesting that this ELISA measures free VEGF. The use of the rat versus mouse ELISA likely explains the differences in reported VEGF concentrations in pregnant rats. While the rat ELISA appears to measure free VEGF, plasma concentrations in nonpregnant and pregnant rats are below the assay sensitivity limit. As most previous studies of pregnant rats used the mouse VEGF ELISA, these data should be interpreted cautiously.

Original language	English (US)
Pages (from-to)	R796-R803
Journal	American Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume	306
Issue number	11
DOIs	https://doi.org/10.1152/ajpregu.00544.2013
State	Published - Jun 1 2014

Keywords

Heparin
Preeclampsia
Pregnancy
Vascular endothelial growth factor
sFLT-1

ASJC Scopus subject areas

General Medicine

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10.1152/ajpregu.00544.2013

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Weissgerber, T. L., McConico, A., Knudsen, B. E., Butters, K. A., Hayman, S. R., White, W. M., Milic, N., Miller, V. M., & Garovic, V. D. (2014). Methodological differences account for inconsistencies in reported free VEGF concentrations in pregnant rats. American Journal of Physiology - Regulatory Integrative and Comparative Physiology, 306(11), R796-R803. https://doi.org/10.1152/ajpregu.00544.2013

Methodological differences account for inconsistencies in reported free VEGF concentrations in pregnant rats. / Weissgerber, Tracey L.; McConico, Andrea; Knudsen, Bruce E. et al.
In: American Journal of Physiology - Regulatory Integrative and Comparative Physiology, Vol. 306, No. 11, 01.06.2014, p. R796-R803.

Research output: Contribution to journal › Article › peer-review

Weissgerber, TL, McConico, A, Knudsen, BE, Butters, KA, Hayman, SR, White, WM, Milic, N, Miller, VM & Garovic, VD 2014, 'Methodological differences account for inconsistencies in reported free VEGF concentrations in pregnant rats', American Journal of Physiology - Regulatory Integrative and Comparative Physiology, vol. 306, no. 11, pp. R796-R803. https://doi.org/10.1152/ajpregu.00544.2013

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abstract = "Free vascular endothelial growth factor (VEGF) is undetectable in plasma during human pregnancy. However, studies examining pregnant rats have reported both low (8-29 pg/ml) and high (527-1,030 pg/ml) free VEGF. These discrepancies cast uncertainty over the use of rat models to study angiogenic factors in pregnancy and preeclampsia. This study investigates methodological factors that may explain these discrepancies. Plasma VEGF in nonpregnant, day 7 pregnant, and day 19 pregnant rats was measured using rat and mouse ELISAs (R&D Systems). The rat ELISA detected VEGF in plasma from nonpregnant rats but not in plasma from day 19 pregnant rats. The mouse ELISA detected higher VEGF concentrations than the rat ELISA in every sample tested. This discrepancy was greater in day 19 pregnant rats (median: 2,273 vs. 0 pg/ml) than in nonpregnant (97 vs. 20 pg/ml) and day 7 pregnant (66 vs. 2 pg/ml) rats. Recovery of recombinant rat VEGF (rrVEGF) spiked into plasma from nonpregnant and day 7 pregnant rats was high for the rat ELISA (82-105%) but low for the mouse ELISA (17-22%). The rat ELISA did not recover rrVEGF in plasma from day 19 pregnant rats, suggesting that this ELISA measures free VEGF. The use of the rat versus mouse ELISA likely explains the differences in reported VEGF concentrations in pregnant rats. While the rat ELISA appears to measure free VEGF, plasma concentrations in nonpregnant and pregnant rats are below the assay sensitivity limit. As most previous studies of pregnant rats used the mouse VEGF ELISA, these data should be interpreted cautiously.",

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AU - Hayman, Suzanne R.

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AU - Milic, Natasa

AU - Miller, Virginia M.

AU - Garovic, Vesna D.

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Methodological differences account for inconsistencies in reported free VEGF concentrations in pregnant rats

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