NCT07227740 · Craig Hospital
Testosterone Deficiency and Endothelial Dysfunction After Spinal Cord Injury
What this study is about
Heart attacks and strokes are among the most common causes of premature death in individuals living with spinal cord injury (SCI) and appear to occur earlier in life. The factors that lead to the heighten and accelerated risk of heart attacks and strokes in adults living with SCI remain poorly understood. The investigators aim to uncover why this happens and find ways to prevent it.
View original scientific description
Heart attacks and strokes are among the most common causes of premature death in individuals living with spinal cord injury (SCI) and appear to occur earlier in life. The factors that lead to the heighten and accelerated risk of heart attacks and strokes in adults living with SCI remain poorly understood. The investigators aim to uncover why this happens and find ways to prevent it. Our research focuses on how important cells which line blood vessels, called endothelial cells, function after SCI. The investigators test endothelial function in live conscious people with SCI. The investigators also study signaling molecules endothelial cells release called endothelial cell derived microvesicles (EMVs), which the investigators can measure in blood to tell us the health of endothelial cells. By using these rigorous tests of vascular function, the investigators have determined that endothelial cells appear dysfunctional after SCI. The investigators also know that many men with SCI have low testosterone levels. Our team has studied testosterone's effects on endothelial dysfunction and believe low testosterone may be contributing to endothelial dysfunction after SCI. By understanding these mechanisms, the investigators hope to improve the lives of those living with SCI and reduce their risk for heart attacks and strokes. The investigators propose to study the influence of testosterone on endothelial function by using state-of-the-art clinical and laboratory experiments to assess endothelial function in men with SCI with low and normal testosterone levels.
Interventions
DIAGNOSTIC_TEST
Intra-arterial Infusion of Vasoactive Agents
A catheter is placed in the brachial artery of the non-dominant arm, and small doses of vasoactive drugs acetylcholine, isoproterenol, sodium nitroprusside are infused. Forearm blood flow will be measured using venous occlusion plethysmography. The purpose of this procedure is to assess endothelium-dependent and independent vasodilation by stimulating different vascular pathways. The acetylcholine infusion is to test muscarinic receptor, nitro oxide dependent, endothelium-dependent vasodilation. Isoproterenol was selected to stimulate tissue plasminogen activator based on its specificity and effectiveness at eliciting local and rapid tissue plasminogen activator release in adult humans. Sodium nitroprusside infusion is to assess endothelium-independent vasodilation.
DIAGNOSTIC_TEST
Intra-arterial Vitamin C Infusion
Vitamin C, a potent antioxidant, will be infused into the forearm and forearm blood flow will be re-evaluated to determine whether oxidative stress contributes to endothelial dysfunction.
DIAGNOSTIC_TEST
Blood Sampling
Blood will be sampled from the antecubital vein (\~50 mL) for biomarker analysis. This is to assess circulating biochemical and molecular indicators of vascular health and inflammation including levels of endothelial cell derived microvesicles.
Primary outcome measures
Endothelium-dependent vasodilation
Time frame: Measured at baseline (without acetylcholine) and immediately after each acetylcholine dose for 3-5 minutes.
Total forearm blood flow with be measured by strain gauge venous plethysmography under baseline conditions and under pharmacological manipulation with acetylcholine at increasing concentrations (8, 16, 32ug/ml).
Endothelium-independent vasodilation
Time frame: Measured at baseline (without sodium nitroprusside) and immediately after each sodium nitroprusside dose for 3-5 minutes.
Total forearm blood flow with be measured by strain gauge venous plethysmography under baseline conditions and under pharmacological manipulation with sodium nitroprusside at increasing concentrations (1, 2, 4ug/ml).
Tissue plasminogen activator release
Time frame: Measured at baseline and immediately after each isoproterenol and sodium nitroprusside dose for 3-5 minutes.
Net endothelial release or uptake of t-PA and PAI-1 (both antigen and activity levels) at each dose of isoproterenol and sodium nitroprusside will be calculated as the product of the arteriovenous concentration gradient and the infused forearm plasma flow. Arteriovenous concentration gradients for both t-PA and PAI-1 antigen and activity for each subject (at each time point) will be determined by subtraction of the values measured in simultaneously collected venous and arterial blood samples
Endothelial cell-derived microvesicles concentration
Time frame: Baseline
Endothelial cell-derived microvesicles will be collected from venous blood samples and counted used flow cytometry to determine a circulating concentration.
Endothelial cell-derived microvesicles effects of human coronary artery endothelial cells nitric oxide bioavailability.
Time frame: Baseline
Endothelial cell-derived microvesicles will be sorted and collected by fluorescence-activated cell sorting (FACS) flow cytometry. The endothelial cell-derived microvesicles will be co-cultured with human coronary artery endothelial cells. Endothelial Nitric Oxide Synthase and phosphorylation sites of interest will be measured by intracellular protein expression quantification of whole cell lysates by capillary electrophoresis immunoassays. Nitric oxide production will be assessed by total nitric oxide and nitrate/nitrite parameter assays
Endothelial cell-derived microvesicles effects of human coronary artery endothelial cells reactive oxygen species and antioxidant capacity
Time frame: Baseline
Endothelial cell-derived microvesicles will be sorted and collected by fluorescence-activated cell sorting (FACS) flow cytometry. The endothelial cell-derived microvesicles will be co-cultured with human coronary artery endothelial cells. Super oxide dismutase and catalase expression will be measured by intracellular protein expression quantification of whole cell lysates by capillary electrophoresis immunoassays. Intracellular oxidative stress will be assessed by ROS-Glo H2O2 assay.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Between ages 18-89 years of age
- History of motor complete (AIS A/B) paraplegia (NLI T3 or Below)
- Time since injury \<6 months at time of enrollment (Subacute injury)
- Testosterone Deficiency defined as \< 300ng/dL
Exclusion criteria
- Overt cardiovascular disease assessed by a) medical history, b) physical examination c) electrocardiogram
- Anaphylaxis to betadine, lidocaine, iodine
- Active infection at time of enrollment.
- Recent surgery (\<1 month) at time of enrollment.
- History smoking tobacco (currently or in the past 12 months)
- History of more than low-risk history of alcohol consumption
- History of drug abuse
- History of use of cardiovascular-acting (i.e. statins, beta-blockers) therapeutics
- History of other health habits, medications, and supplements that could influence the outcome measures deemed by principal investigators and investigative team.
Where
- Englewood, Colorado
Collaborators
University of Colorado, Boulder, Denver Health and Hospital Authority, University of Colorado, Denver
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Nov 21, 2025 · Source of record for eligibility and locations