Opposing effects of heparin with TGF‐β or aFGF during repair of a mechanical wound of human endothelium. Influence of cAMP on cell migration

Abstract

The effects on vascular wound repair in vitro of aFGF and TGF-beta, growth factors having opposite influences on endothelial cell growth and angiogenesis, were studied using as a model a mechanical lesion of confluent endothelium. Modulation by heparin of the activities of these growth factors during the repair process was also examined. Whereas heparin alone inhibited repair by lowering both cell proliferation and cell migration, TGF-beta alone mainly inhibited cell proliferation. When added together, TGF-beta and heparin exerted a combined inhibitory effect resulting in a residual lesion 50% larger than in controls. aFGF alone accelerated lesion coverage and this effect was enhanced by 40% over control values when heparin was added with aFGF. This acceleration was slightly (less than 10%) but consistently diminished by TGF-beta. Cell density in confluent unwounded areas was increased by 40% in the presence of aFGF, but TGF-beta diminished cell density by 20%. A small (30%) increase in intracellular cAMP was measured whenever aFGF was present during the repair process. In comparison, intracellular cAMP inducing agents (forskolin, dbcAMP) accelerated cell migration by 20% during lesion recovery without affecting cell proliferation or density. The present results show that the inhibitory effects of TGF-beta during vascular wound repair are opposed by aFGF. Furthermore, heparin (or heparan sulfates in vivo) modulates growth factors having activating or inhibiting functions and thus plays a regulatory role during the repair process. cAMP-inducing substances other than growth factors are able to accelerate cell migration.

Stimulatory effects of dibutyryl cyclic adenosine monophosphate on cytokine production by keratinocytes and fibroblasts

“…However, other cytokines, such as EGF and TGF-a, which were not examined in the present study, may be involved to a small extent because the stimulation of keratinocyte proliferation was not completely inhibited by anti-IL-6 MoAb, even at concentrations as high as 50 mg mL 21 . 9,14,30 From these results, we conclude that DBcAMP stimulates epithelialization with keratinocytes through an increase in IL-6 production by fibroblasts, and that it also transiently enhances the production of TGF-b1 by fibroblasts at an early stage of incubation. This series of actions on the stimulation of production of cytokines, together with the enhancement of cell migration, 18 are thought to be the mechanisms of action of DBcAMP in clinically stimulating the healing of skin ulcers, particularly chronic wounds, 7,31 such as decubitus ulcers.…”

Stimulatory effects of dibutyryl cyclic adenosine monophosphate on cytokine production by keratinocytes and fibroblasts

“…These results suggest that the production of IL‐6 by fibroblasts was increased by DBcAMP, and the increased IL‐6 stimulated keratinocyte proliferation. However, other cytokines, such as EGF and TGF‐α, which were not examined in the present study, may be involved to a small extent because the stimulation of keratinocyte proliferation was not completely inhibited by anti‐IL‐6 MoAb, even at concentrations as high as 50 μg mL −1 9,14 , 30 …”

Intracellular Distribution of Gravin, a PKA and PKC Binding Protein, in Vascular Endothelial Cells

“…This proposal is consistent with the finding in several studies that PKA and PKC agonists and inhibitors effect several cellular activities associated with wound repair in endothelia and other epithelial cell types. Cell proliferation and migration in vascular and corneal endothelial cells have been found to be effected by PKA and PKC agonists and inhibitors in several diverse studies [18, 19, 20, 21, 22, 23, 24]. In addition, the expression of certain proteins having roles in wound repair and angiogenesis have been found to be PKA and PKC dependent.…”