Abstract:Angiogenesis represents a form of neovascularisation of exceptional importance in numerous pathological conditions including stroke. In this context it is directly related to neuroregeneration which is seen in close proximity. However, numerous experimental data have been drawn from studies that have ignored the age criterion. This is extremely important as angiogenesis is different in young versus old subjects. Extrapolating data obtained from studies performed in young subjects or "in vitro" to old-age patie… Show more
“…This concurs once again with the findings of two studies that analyzed the Sleep Heart Health Study cohort, which showed an increase in the incidence of new cardiovascular events caused by heart failure in the subgroup of elderly patients with OSA (25) or stroke (median age of stroke patients: 72 years) (27), although cardiovascular mortality was not analyzed in these studies. Although it could be supposed that the 'ischemic preconditioning' hypothesis would endorse protection against intermittent hypoxia in any type of cardiovascular event, most of the data available on this compensatory mechanism derive from studies investigating its effect on coronary circulation (38)(39)(40), and the effect on cerebral circulation is much more open to debate, particularly in the case of elderly people (41)(42)(43). Thus, Wegener et al reported that the protection provided against stroke development by an earlier period of cerebral ischemia (e.g.…”
“…This concurs once again with the findings of two studies that analyzed the Sleep Heart Health Study cohort, which showed an increase in the incidence of new cardiovascular events caused by heart failure in the subgroup of elderly patients with OSA (25) or stroke (median age of stroke patients: 72 years) (27), although cardiovascular mortality was not analyzed in these studies. Although it could be supposed that the 'ischemic preconditioning' hypothesis would endorse protection against intermittent hypoxia in any type of cardiovascular event, most of the data available on this compensatory mechanism derive from studies investigating its effect on coronary circulation (38)(39)(40), and the effect on cerebral circulation is much more open to debate, particularly in the case of elderly people (41)(42)(43). Thus, Wegener et al reported that the protection provided against stroke development by an earlier period of cerebral ischemia (e.g.…”
“…It should be noted that angiogenesis is not always detected in peri-infarct area. Aging is a complex and significant factor that impacts post-ischemic angiogenesis (Petcu et al, 2010). Hypoxia-inducible angiogenesis in rodent hippocampus decreases with aging (Ingraham et al, 2008).…”
Section: The Role Of Angiogenesis In Cerebrovascular Diseases Andmentioning
The brain vasculature has been increasingly recognized as a key player that directs brain development, regulates homeostasis, and contributes to pathological processes. Following ischemic stroke, the reduction of blood flow elicits a cascade of changes and leads to vascular remodeling. However, the temporal profile of vascular changes after stroke is not well understood. Growing evidence suggests that the early phase of cerebral blood volume (CBV) increase is likely due to the improvement in collateral flow, also known as arteriogenesis, whereas the late phase of CBV increase is attributed to the surge of angiogenesis. Arteriogenesis is triggered by shear fluid stress followed by activation of endothelium and inflammatory processes, while angiogenesis induces a number of pro-angiogenic factors and circulating endothelial progenitor cells (EPCs). The status of collaterals in acute stroke has been shown to have several prognostic implications, while the causal relationship between angiogenesis and improved functional recovery has yet to be established in patients. A number of interventions aimed at enhancing cerebral blood flow including increasing collateral recruitment are under clinical investigation. Transplantation of EPCs to improve angiogenesis is also underway. Knowledge in the underlying physiological mechanisms for improved arteriogenesis and angiogenesis shall lead to more effective therapies for ischemic stroke.
“…Two key parameters influence restoration of blood flow: presence of collaterals and a capacity to undergo vascular remodeling and produce angiogenic mediators. A majority of the research reveals that spontaneous vascular remodeling occurs after TBI and stroke [71,72 ▪ ,73] with exceptions that show the absence of vascular remodeling depending upon the region of assessment [74], impaired plasticity and remodeling associated with age [75–77] and comorbid conditions [78,79]. Vascular modeling is associated with improved neurological outcomes [73].…”
Section: Reparative Neovascularization After Stroke and Traumatic Bramentioning
Purpose of review
Angiogenesis or vascular reorganization plays a role in recovery after stroke and traumatic brain injury (TBI). In this review, we have focused on two major events that occur during stroke and TBI from a vascular perspective – what is the process and time course of blood–brain barrier (BBB) breakdown? and how does the surrounding vasculature recover and facilitate repair?
Recent findings
Despite differences in the primary injury, the BBB changes overlap between stroke and TBI. Disruption of BBB involves a series of events: formation of caveolae, trans and paracellular disruption, tight junction breakdown and vascular disruption. Confounding factors that need careful assessment and standardization are the severity, duration and extent of the stroke and TBI that influences BBB disruption. Vascular repair proceeds through long-term neovascularization processes: angiogenesis, arteriogenesis and vasculogenesis. Enhancing each of these processes may impart beneficial effects in endogenous recovery.
Summary
Our understanding of BBB breakdown acutely after the cerebrovascular injury has come a long way; however, we lack a clear understanding of the course of BBB disruption and BBB recovery and the evolution of individual cellular events associated with BBB change. Neovascularization responses have been widely studied in stroke for their role in functional recovery but the role of vascular reorganization after TBI in recovery is much less defined.
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