Effects of Fetal Size on Gene Expression and Glucose Uptake By d 60 Porcine Umbilical Cord Cells.

Low birth weight (LBW) pigs have a delay in adipogenic development and exhibit rapid catch up growth after birth. Wharton’s jelly (WJ) in umbilical cords is a source of mesenchymal stem cells that can differentiate into preadipocytes and adipocytes. Human WJ cells have been suggested as an in vitro model for the effects of intrauterine growth retardation. Differences were previously found in WJ gene expression of EGR1 and Cox2 between LBW and normal birth weight pigs at term. The objective of this study was to evaluate effects of fetus size and adipocyte differentiation on adipogenic gene expression and glucose uptake by WJ cells at d 60 of gestation. Thirty-six umbilical cords were collected from male fetuses (small, medium and large) of twelve pregnant gilts (PIC; 327x1050). Cords were frozen, thawed and processed to 1-3mm³ explants. The cells that grew out were cultured for 3 passages. Adipocyte differentiation (n = 5 cords/size) used two media: adipocyte induction and insulin resting media applied for 6 cycles. Media for the resting phase was assayed for glucose to determine uptake and cells were counted and lysed for RNA extraction at cycles 0, 1, 3, and 6. Quantitative real time PCR was used to determine gene expression with 18s as the housekeeping gene. Glucose concentration was determined (QuantiChrom Glucose Assay Kit). Glucose uptake increased (P < 0.05) from cycle 0 to cycle 6. At cycle 0 and 6 fetal weight was negatively correlated with glucose uptake (R² = 0.50, P < 0.005 and 0.38, P < 0.05, respectively). Expression of all genes changed between cycle 0 and 6. PPARɣ1 and PPARɣ2 decreased (P < 0.005) expression from cycle 0 to 6, while Pref1, EGR1, Cox1, and Cox2 expression increased (P < 0.05) from cycle 0 to 6. Fetal weight was negatively correlated with PPARɣ2 (cycle 0, R² = 0.34; P < 0.03) and positively correlated with Cox1 (cycle 0; R² = 0.35, P < 0.03 and 6; R² = 0.29, P < 0.04) gene expression in WJ cells. Therefore differences in adipocyte gene expression and glucose uptake related to fetal growth restriction are present in WJ cells from d 60 fetuses. Staining did not reveal lipid droplets in these WJ cells. These results indicate that WJ cells at d 60 of pregnancy are affected by fetal growth restriction but are not fully competent for adipogenic differentiation.