The role of fibrinolytic factors in ischaemia

Inhibition of PAI-1 Via PAI-039 Improves Dermal Wound Closure in Diabetes

Diabetes impairs the ability to heal cutaneous wounds, leading to hospitalization, amputations, and death. Patients with diabetes experience elevated levels of plasminogen activator inhibitor 1 (PAI-1), regardless of their glycemic control. It has been demonstrated that PAI-1-deficient mice exhibit improved cutaneous wound healing, and that PAI-1 inhibition improves skeletal muscle repair in mice with type 1 diabetes mellitus, leading us to hypothesize that pharmacologically mediated reductions in PAI-1 using PAI-039 would normalize cutaneous wound healing in streptozotocin (STZ)-induced diabetic (STZ-diabetic) mice. To simulate the human condition of variations in wound care, wounds were aggravated or minimally handled postinjury. Following cutaneous injury, PAI-039 was orally administered twice daily for 10 days. Compared with nondiabetic mice, wounds in STZ-diabetic mice healed more slowly. Wound site aggravation exacerbated this deficit. PAI-1 inhibition had no effect on dermal collagen levels or wound bed size. PAI-039 treatment failed to improve angiogenesis in the wounds of STZ-diabetic mice and blunted angiogenesis in the wounds of nondiabetic mice. Importantly, PAI-039 treatment significantly improved epidermal cellular migration and wound re-epithelialization compared with vehicle-treated STZ-diabetic mice. These findings support the use of PAI-039 as a novel therapeutic agent to improve diabetic wound closure and demonstrate the primary mechanism of its action to be related to epidermal closure.

Relationships between lipoprotein(a), lipids, apolipoproteins, basal and stimulated fibrinolytic regulators, and D-dimer

In 191 newly referred hyperlipidemic patients, our specific aim was to assess relationships between levels of lipoprotein(a) [Lp(a)], lipids, apolipoproteins, regulators of basal and stimulated fibrinolytic activity, and D-dimer, a measure of in vivo fibrinolysis. Lp(a) levels correlated with none of the measures of basal fibrinolytic regulators or D-dimer. In 25 patients, levels of stimulated regulators of fibrinolytic activity and D-dimer were measured after 10-minute cuff venous occlusion. Lp(a) levels again correlated with none of the stimulated regulators of fibrinolytic activity or D-dimer. However, both basal and stimulated levels of fibrinolytic regulators and D-dimer were closely related to other major risk factors for coronary heart disease (CHD) including triglyceride, apolipoprotein (apo) A1, apo B, Quetelet index (QI), and sex. By stepwise regression in 191 patients, the following standardized partial regression coefficients were significant (P < or = .05), and model R2 and P values were as follows: basal tissue plasminogen activator (tPA) with apo B-.18, with time .17, with QI -.28, R2 = 17%, P < or = .0001; basal plasminogen activator inhibitor (PAI) with apo B..25, with time -.15, with QI .17, R2 = 14%, P < or = .0001; basal alpha 2-antiplasmin with apo A1.14, with apo B.24, with QI.17, with sex .30, R2 = 25%, P < .0001; basal plasminogen with A1.15, with apo B.21, with QI.17, with sex.17, R2 = 15%, P < or = .0001; basal fibrinogen with Lp(a).17, with QI.21, with sex.26, R2 = 14%, P < or = .0001; D-dimer with sex.15, R2 = 21%, P < or = .048. Given the absence of any relationship between Lp(a) levels and inhibition or stimulation of fibrinolysis regulators or D-dimer either in the basal or stimulated state, we postulate that Lp(a)'s major atherogenic effects are mediated by mechanisms other than reduction of fibrinolysis stimulation or in vivo fibrinolysis.