Effect of age and hypoxia on TGFβ1 receptor expression and signal transduction in human dermal fibroblasts: Impact on cell migration

Abstract

Wound healing is critically affected by age, ischemia, and growth factors such as TGFbeta1. The combined effect of these factors on fibroblast migration, an essential component of wound healing, is poorly understood. To address this deficiency, we examined expression of TGFbeta receptor type I and II (TGFbetaRI and RII) under normoxia or hypoxia (1% O(2)) in cultured human dermal fibroblasts (HDFs) from young (ages 24-33) and aged (ages 61-73) adults. TGFbetaRI and RII expression was similar in both groups under normoxia. Hypoxia did not alter receptor levels in young HDFs but significantly decreased TGFbetaRI in aged cells (12 and 43%, respectively). Additionally, young cells displayed a 50% increase in activation of p42/p44 mitogen-activated kinase by TGFbeta1 (2-200 pg/ml) under hypoxia while aged cell levels of active p42/p44 decreased up to 24%. To determine functional outcomes of these findings, we measured the migratory capacity of the cells on type I collagen using a gold salt migration assay. Hypoxia increased the migratory index (MI) of young HDFs over normoxia by 30% but had no effect on aged cells. Under normoxia, TGFbeta1 (1-1000 pg/ml) increased young HDF migration in a concentration-dependent manner up to 109% over controls but minimally increased aged HDF migration (37%). Under hypoxia, TGFbeta1 significantly increased young cell MI at all concentrations but was without effect on the aged HDF response. These data demonstrate that aged fibroblasts have an impaired migratory capacity with complete loss of responsiveness to hypoxia and deficits in the migratory and signal transduction responsiveness to TGFbeta1 that may partly explain diminished healing capabilities often observed in aged patients.

Provisional Matrix Deposition in Hemostasis and Venous Insufficiency: Tissue Preconditioning for Nonhealing Venous Ulcers

“…109,110 Mogford et al reported that fibroblasts grown in a chronically hypoxic environment expressed lower levels of type I and type II TGF-b 1 receptors (TGFbRI & II). 111 This supported previous work by others which demonstrated that primary dermal fibroblasts exposed to acute hypoxic conditions ( < 1 week) in vitro, results in cellular proliferation, TGF-b 1 expression and type I collagen production. However, exposure to prolonged culture in hypoxic conditions ( > 1 week), thus, mimicking an ischemic dermal environment, did not support these processes.…”

Gene delivery through cell culture substrate adsorbed DNA complexes

“…Human dermal fibroblasts (HDF) were obtained per protocol of the IRB and Office for the Protection of Research Subjects at Northwestern University and cultured as previously described (Mogford et al, 2002). Cells were seeded at a density of 5,000 cells per well in 96-well plates.…”

Effect of a caloric restriction regimen on the angiogenic capacity of aorta and on the expression of endothelin-1 during ageing

“…Ageing is a universal process affecting most cells, and concurrent studies in vitro have confirmed that the age-related delay in angiogenesis is associated with several deficits in cell functions. The latter include slowed migration of aged microvascular endothelial cells (Reed et al, 2000) and fibroblasts (Reed et al, 2001;Mogford et al, 2002); lower nitric oxide (NO) production and increased sensitivity of endothelial cells to apoptotic stimuli (Vasa et al, 2000;Hoffmann et al, 2001;Chavakis and Dimmeler, 2002); a defective response in aged cells to the mitogenic effects of vascular endothelium growth factor (VEGF) (Rivard et al 1999) and the antiproliferative effects of transforming growth factor (TGF)-β1 (McCaffrey and Falcone, 1993).…”