Granulocyte Colony-Stimulating Factor Improves Cerebrovascular Reserve Capacity by Enhancing Collateral Growth in the Circle of Willis

Abstract

Background and Purpose: Restoration of cerebrovascular reserve capacity (CVRC) depends on the recruitment and positive outward remodeling of preexistent collaterals (arteriogenesis). With this study, we provide functional evidence that granulocyte colony-stimulating factor (G-CSF) augments therapeutic arteriogenesis in two animal models of cerebral hypoperfusion. We identified an effective dosing regimen that improved CVRC and stimulated collateral growth, thereby improving the outcome after experimentally induced stroke. Methods: We used two established animal models of (a) cerebral hypoperfusion (mouse, common carotid artery ligation) and (b) cerebral arteriogenesis (rat, 3-vessel occlusion). Following therapeutic dose determination, both models received either G-CSF, 40 µg/kg every other day, or vehicle for 1 week. Collateral vessel diameters were measured following latex angiography. Cerebrovascular reserve capacities were assessed after acetazolamide stimulation. Mice with left common carotid artery occlusion (CCAO) were additionally subjected to middle cerebral artery occlusion, and stroke volumes were assessed after triphenyltetrazolium chloride staining. Given the vital role of monocytes in arteriogenesis, we assessed (a) the influence of G-CSF on monocyte migration in vitro and (b) monocyte counts in the adventitial tissues of the growing collaterals in vivo. Results: CVRC was impaired in both animal models 1 week after induction of hypoperfusion. While G-CSF, 40 µg/kg every other day, significantly augmented cerebral arteriogenesis in the rat model, 50 or 150 µg/kg every day did not show any noticeable therapeutic impact. G-CSF restored CVRC in mice (5 ± 2 to 12 ± 6%) and rats (3 ± 4 to 19 ± 12%). Vessel diameters changed accordingly: in rats, the diameters of posterior cerebral arteries (ipsilateral: 209 ± 7–271 ± 57 µm; contralateral: 208 ± 11–252 ± 28 µm) and in mice the diameter of anterior cerebral arteries (185 ± 15–222 ± 12 µm) significantly increased in the G-CSF groups compared to controls. Stroke volume in mice (10 ± 2%) was diminished following CCAO (7 ± 4%) and G-CSF treatment (4 ± 2%). G-CSF significantly increased monocyte migration in vitro and perivascular monocyte numbers in vivo. Conclusion: G-CSF augments cerebral collateral artery growth, increases CVRC and protects from experimentally induced ischemic stroke. When comparing three different dosing regimens, a relatively low dosage of G-CSF was most effective, indicating that the common side effects of this cytokine might be significantly reduced or possibly even avoided in this indication.

The Role of Citicoline in Neuroprotection and Neurorepair in Ischemic Stroke

“…Citicoline treatment decreased neuronal apoptosis and promoted endogenous cerebral repair [80]. A well-known experimental study conducted at Madrid’s Complutense University demonstrated that treatment with citicoline 24 h after MCA occlusion in rats produced an increase in neuronal synaptic spines with increased motor and functional recovery in treated animals [50].…”

Knockout of Density-Enhanced Phosphatase-1 Impairs Cerebrovascular Reserve Capacity in an Arteriogenesis Model in Mice

“…We assessed DEP-1 deficiency in a mouse model [25] capable of inducing cerebral arteriogenesis by CCAO. In order to be able to detect either a positive or a negative impact on collateral growth due to loss of DEP-1, day 7 after operation was chosen as a read-out for collateral growth.…”

“…Cerebral hypoperfusion was induced by unilateral permanent left common carotid artery occlusion (CCAO), as previously described [25]. Cerebrovascular architecture was determined 7 days after operation after maximal vasodilation with 1 mg/kg adenosine using a modified postmortem latex perfusion [29].…”

“…Thus, here we analyzed the biological function of DEP-1 in vivo on collateral growth using DEP-1 −/− mice. Cerebral arteriogenesis was assessed with a recently established permanent common carotid artery occlusion model in mice [25]. Furthermore, we subjected DEP-1 −/− mice and wild-type littermates to a peripheral arteriogenesis model based on occlusion of the femoral artery [26].…”

The Efficacy and Safety of Granulocyte Colony-Stimulating Factor for Patients with Stroke

“…[28][29][30] This therapy has several advantages over traditional treatments such as aspirin and thrombolytic agents because the therapy is less invasive, relatively safe, ethically acceptable, and has a wider therapeutic window. 31 Similarly, well-tolerated administration, feasible treatment regimen, and improved neurologic outcomes have been reported in the individual studies.…”