DESCRIPTION

PlGF (placenta growth factor), also named as PGF, is an angiogenic factor which belongs to vascular endothelial growth factor (VEGF) family. The human PlGF gene is located on chromosome 14q14 and encodes 4 isoforms of PlGF. The protein is secreted as a glycosylated homodimer and PlGF-1 and -3 are diffusible isoforms whereas PlGF-2 and PlGF-4 have heparin binding domains. PlGF was originally identified in the placenta, where it regulates growth and differentiation of trophoblasts. It is also expressed in umbilical vein endothelial cells and other non-placental tissues, like the thyroid gland and developing lung tissue. PlGF has angiogenic properties, enhancing survival, growth and migration of endothelial cells in vitro, and promotes vessel formation in certain in-vivo models. Serum levels of PIGF and sFlt-1 (also known as soluble VEGF receptor-1) are altered in women with preeclampsia. PIGF is a potential biomarker for preeclampsia, a condition in which blood vessels in the placenta are too narrow, resulting in high blood pressure.

PRINCIPLE OF THE ASSAY

An anti-tag antibody is pre-coated onto the bottom of wells. After adding antigen or samples, Tagged-Capture antibody and HRP-conjugated detection antibody, a sandwich complex is formed in the solution. TMB acts as a HRP substrate, and the solution color will change from colorless to blue. A stop solution containing sulfuric acid turns the solution yellow. The color intensity is proportional to the quantity of bound protein, which is measurable at 450 nm with the correction wavelength set at 630 nm.

PRECISION

Intra-assay Precision (Precision within an assay) Three samples of known concentration were tested 8 times on one plate to assess intra-assay precision. Inter-assay Precision (Precision between assays) Three samples of known concentration were tested in 16 separate assays to assess inter-assay precision.

Intra-assay Precision

Sample	n	Mean (pg/mL)	SD	CV%
1	8	2,264.7	49.9	2.2
2	8	505.4	8.8	1.7
3	8	253.7	5.2	2.0

Inter-assay Precision

Sample	n	Mean (pg/mL)	SD	CV%
1	16	2,257.5	53.6	2.4
2	16	498.6	10.9	2.2
3	16	248.8	7.9	3.2

RECOVERY

The recovery of mouse PGF/PLGF spiked to three different levels throughout the range of the assay in various matrices was evaluated.

Sample Type		Average% of Expected	Range (%)
Mouse serum	1:2	77	73-81
Cell culture supernatant	1:4	109	107-111
	1:8	112	109-115

LINEARITY

To assess the linearity of the assay, mouse serum samples were spiked with high concentrations of mouse PGF/PLGF and diluted with the appropriate Sample Diluent to produce samples with values within the dynamic range of the assay. Cell culture supernatant samples were diluted with the appropriate Sample Diluent to produce samples with values within the dynamic range of the assay.

		Mouse serum	Cell culture supernatant
1:2	Average% of Expected	76	100
	Range (%)	73-78	-
1:4	Average% of Expected	94	87
	Range (%)	89-94	84-91
1:8	Average% of Expected	118	96
	Range (%)	117-119	96-97
1:16	Average% of Expected	128	89
	Range (%)	127-129	88-91

CALIBRATION

This immunoassay is calibrated against a highly purified recombinant human Mouse PGF/PLGF One-Step ELISA Kit produced at Sunlong Medical™.