Platelet AggregationNCT07275541
Platelet Aggregation in the Diagnosis of Acute Graft Rejection
An observational study of Platelet Aggregation and Kidney Transplant Rejection, run by University Hospital, Martin at 1 site in Slovakia.
Trial summary
The study titled "Platelet Aggregation in the Diagnosis of Acute Graft Rejection" is a pilot observational study evaluating whether alterations in platelet function can serve as non-invasive markers of acute rejection in kidney transplant recipients. Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Platelet Aggregation, Kidney Transplant Rejection
- How many people
- 60 participants
- Where
- 1 siteSlovakia
- Study dates
- 26 Nov 2024to 26 Nov 2027
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Study population: Patients with chronic kidney disease who underwent kidney transplantation
Who may be able to join
- adult patients (≥18 years)
- primary kidney transplantation
- living / deceased donor kidney transplantation
- ability and consent to participate
Who cannot join
- non-adult patients
- secondary / tertiary kidney transplantation
- antiplatelet therapy
- patients unable to provide informed consent
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Slovakia1 site, 1 recruiting
- Recruiting
Transplant-Nephrology Department, University Hospital Martin
Martin, 03601
Timea Blichova, MD, +421434203184, tc@unm.sk
Matej Vnucak, ass prof., MD, PhD., +421434203184, tc@unm.sk
About this study
The study titled "Platelet Aggregation in the Diagnosis of Acute Graft Rejection" is a pilot observational study evaluating whether alterations in platelet function can serve as non-invasive markers of acute rejection in kidney transplant recipients. Platelet aggregation is assessed using optical aggregometry, flow-cytometric P-selectin (CD62-P) expression, and soluble P-selectin levels before kidney transplantation and at the time of protocol biopsies performed at 3 and 12 months after kidney transplantation. Patients with suspected graft dysfunction undergoing indication biopsy are also included. Platelet activation markers are correlated with histopathological findings, donor-specific antibodies, metabolic parameters, and clinical outcomes. The goal is to determine whether platelet activation profiles can identify acute cellular or antibody-mediated rejection and contribute to the development of a non-invasive diagnostic tool.
Read the detailed description
Platelets play a key role not only in hemostasis but also in inflammation and immune responses. Their activation, characterized by adhesion, integrin-mediated aggregation, thromboxane A₂ production, and surface expression of markers such as P-selectin, contributes to interactions with T lymphocytes and amplification of immune signaling. Emerging evidence suggests that platelet activation may participate in early mechanisms of kidney graft injury. Studies have demonstrated platelet accumulation in glomerular and peritubular capillaries during antibody-mediated rejection, likely mediated by donor-specific antibodies and endothelial activation via von Willebrand factor. Elevated platelet activation markers such as PF4 and P-selectin have also been associated with T-cell-mediated rejection.
This pilot study investigates whether changes in platelet aggregation and platelet activation markers can serve as non-invasive indicators of acute kidney allograft rejection. Platelet function is measured using optical aggregometry, flow cytometry of P-selectin (CD62-P), and soluble P-selectin levels. These parameters are correlated with histological findings from protocol biopsies at 3 and 12 months post-transplant, as well as from indication biopsies performed for suspected rejection. The study includes adult kidney transplant recipients monitored longitudinally and a cohort of patients with graft dysfunction requiring indication biopsy. Concurrent assessments include renal function, donor-specific antibodies, levels of immunosupression (tacrolimus), metabolic parameters, and imaging. By comparing platelet activation profiles with biopsy-proven rejection, the study aims to determine whether platelet-based biomarkers can support early, non-invasive detection of cellular or antibody-mediated allograft injury and complement traditional biopsy-based diagnostics.
- Conditions
- Platelet Aggregation, Kidney Transplant Rejection
- Keywords
- kidney transplantation, platelet aggregation, acute rejection, non-invasive marker
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
| Study group | Role | What they receive |
|---|---|---|
| kidney transplant recipients - Protocol Biopsy Cohort | Adult kidney transplant recipients undergoing routine protocol biopsies at 3 and 12 months post-transplant, regardless of clinical graft function. Platelet aggregation, flow-cytometric P-selectin expression, soluble P-selectin levels, and biochemical and immunological parameters are collected at each time point. Findings from platelet function testing are subsequently correlated with the histopathological results of the protocol biopsy, including the presence or absence of subclinical rejection. | |
| kidney transplant recipients - Indication Biopsy Cohort | Kidney transplant recipients presenting with clinical signs of graft dysfunction-such as rising serum creatinine, increasing proteinuria, or abnormal ultrasound findings or with newly positive donor-specific antibodies (DSA) detected by Luminex testing, prompting the need for an indication biopsy due to suspected acute rejection. At the time of biopsy, platelet aggregation testing, P-selectin markers, comprehensive biochemical parameters, and DSA levels are collected. This cohort represents patients with clinically or immunologically apparent graft injury, allowing comparison with protocol-biopsied patients, including those with subclinical or biopsy-confirmed rejection. |
What is being measured
The primary outcome is the main question the study is designed to answer.
To compare changes in platelet aggregation in patients before and after kidney transplantation
Platelet aggregation measured by optical aggregometry before kidney transplantation will be compared with platelet aggregation measured at 3 and 12 months after transplantation to assess changes in platelet function over time.
Measured: Pre-transplant baseline; 3 months post-transplant; 12 months post-transplant
To evaluate the changes in platelet aggregation in the diagnosis of humoral/cellular graft rejection (at the time of biopsy due to graft dysfunction)
Platelet aggregation will be assessed at the time of an indication biopsy performed for graft dysfunction and compared between patients with biopsy-proven humoral or cellular rejection and those without rejection. The aim is to determine whether altered platelet aggregation is associated with acute graft rejection identified on histopathology.
Measured: At the time of indication biopsy (any time after transplantation)
To investigate the use of P-selectin as a potential marker of platelet activation in the diagnosis of acute graft rejection as part of a non-invasive investigation
Flow-cytometric P-selectin (CD62-P) expression on platelets and soluble P-selectin levels in plasma will be measured before and after kidney transplantation and at the time of protocol or indication biopsy. These values will be compared between patients with and without biopsy-proven rejection to assess whether P-selectin can serve as a reliable marker of platelet activation associated with acute graft injury and support the development of a non-invasive diagnostic approach.
Measured: Pre-transplant baseline; at 3- and 12-month protocol biopsies; and at the time of any indication biopsy after kidney transplantation
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted10 Dec 2025
- Study start26 Nov 2024
- Primary completion26 Nov 2026 (estimated)
- Study completion26 Nov 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Platelet AggregationStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 60 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University Hospital, Martin
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Matej Vnucak, University Hospital, Martin
- Investigators
- Matej Vnucak, ass prof, MD, PhD., Study chair, University Hospital Martin and Jessenius Faculty of Medicine, Comenius University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07275541
- Sponsor's protocol ID
- TNO_AGRE
- Other IDs
- UK/3248/2024
- Status last verified
- Nov 2025
- First submitted
- 27 Nov 2025
- Last updated
- 10 Dec 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: It is a monocenter pilot study
Study at a glance
From the registry record, last updated by the sponsor on 10 Dec 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Platelet Aggregation in the Diagnosis of Acute Graft Rejection
- ClinicalTrials.gov ID
- NCT07275541
- Acronym / sponsor ID
- TNO_AGRE
- Conditions
- Platelet Aggregation, Kidney Transplant Rejection
- Keywords
- kidney transplantation, platelet aggregation, acute rejection, non-invasive marker
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 60 participants (estimated)
- Lead sponsor
- University Hospital, MartinUniversity, hospital or other
- Study start
- 26 Nov 2024 (actual)
- Primary completion
- 26 Nov 2026 (estimated)
- Study completion
- 26 Nov 2027 (estimated)
- First posted
- 10 Dec 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The study titled "Platelet Aggregation in the Diagnosis of Acute Graft Rejection" is a pilot observational study evaluating whether alterations in platelet function can serve as non-invasive markers of acute rejection in kidney transplant recipients. Platelet aggregation is assessed using optical aggregometry, flow-cytometric P-selectin (CD62-P) expression, and soluble P-selectin levels before kidney transplantation and at the time of protocol biopsies performed at 3 and 12 months after kidney transplantation. Patients with suspected graft dysfunction undergoing indication biopsy are also included. Platelet activation markers are correlated with histopathological findings, donor-specific antibodies, metabolic parameters, and clinical outcomes. The goal is to determine whether platelet activation profiles can identify acute cellular or antibody-mediated rejection and contribute to the development of a non-invasive diagnostic tool.
Detailed description
Platelets play a key role not only in hemostasis but also in inflammation and immune responses. Their activation, characterized by adhesion, integrin-mediated aggregation, thromboxane A₂ production, and surface expression of markers such as P-selectin, contributes to interactions with T lymphocytes and amplification of immune signaling. Emerging evidence suggests that platelet activation may participate in early mechanisms of kidney graft injury. Studies have demonstrated platelet accumulation in glomerular and peritubular capillaries during antibody-mediated rejection, likely mediated by donor-specific antibodies and endothelial activation via von Willebrand factor. Elevated platelet activation markers such as PF4 and P-selectin have also been associated with T-cell-mediated rejection.
This pilot study investigates whether changes in platelet aggregation and platelet activation markers can serve as non-invasive indicators of acute kidney allograft rejection. Platelet function is measured using optical aggregometry, flow cytometry of P-selectin (CD62-P), and soluble P-selectin levels. These parameters are correlated with histological findings from protocol biopsies at 3 and 12 months post-transplant, as well as from indication biopsies performed for suspected rejection. The study includes adult kidney transplant recipients monitored longitudinally and a cohort of patients with graft dysfunction requiring indication biopsy. Concurrent assessments include renal function, donor-specific antibodies, levels of immunosupression (tacrolimus), metabolic parameters, and imaging. By comparing platelet activation profiles with biopsy-proven rejection, the study aims to determine whether platelet-based biomarkers can support early, non-invasive detection of cellular or antibody-mediated allograft injury and complement traditional biopsy-based diagnostics.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| kidney transplant recipients - Protocol Biopsy Cohort | – | –Adult kidney transplant recipients undergoing routine protocol biopsies at 3 and 12 months post-transplant, regardless of clinical graft function. Platelet aggregation, flow-cytometric P-selectin expression, soluble P-selectin levels, and biochemical and immunological parameters are collected at each time point. Findings from platelet function testing are subsequently correlated with the histopathological results of the protocol biopsy, including the presence or absence of subclinical rejection. |
| kidney transplant recipients - Indication Biopsy Cohort | – | –Kidney transplant recipients presenting with clinical signs of graft dysfunction-such as rising serum creatinine, increasing proteinuria, or abnormal ultrasound findings or with newly positive donor-specific antibodies (DSA) detected by Luminex testing, prompting the need for an indication biopsy due to suspected acute rejection. At the time of biopsy, platelet aggregation testing, P-selectin markers, comprehensive biochemical parameters, and DSA levels are collected. This cohort represents patients with clinically or immunologically apparent graft injury, allowing comparison with protocol-biopsied patients, including those with subclinical or biopsy-confirmed rejection. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
- Study population
- Patients with chronic kidney disease who underwent kidney transplantation
Key inclusion criteria (4 listed)
- adult patients (≥18 years)
- primary kidney transplantation
- living / deceased donor kidney transplantation
- ability and consent to participate
Key exclusion criteria (4 listed)
- non-adult patients
- secondary / tertiary kidney transplantation
- antiplatelet therapy
- patients unable to provide informed consent
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Primary outcome
To compare changes in platelet aggregation in patients before and after kidney transplantation
Time frame: Pre-transplant baseline; 3 months post-transplant; 12 months post-transplant
Platelet aggregation measured by optical aggregometry before kidney transplantation will be compared with platelet aggregation measured at 3 and 12 months after transplantation to assess changes in platelet function over time.
To evaluate the changes in platelet aggregation in the diagnosis of humoral/cellular graft rejection (at the time of biopsy due to graft dysfunction)
Time frame: At the time of indication biopsy (any time after transplantation)
Platelet aggregation will be assessed at the time of an indication biopsy performed for graft dysfunction and compared between patients with biopsy-proven humoral or cellular rejection and those without rejection. The aim is to determine whether altered platelet aggregation is associated with acute graft rejection identified on histopathology.
To investigate the use of P-selectin as a potential marker of platelet activation in the diagnosis of acute graft rejection as part of a non-invasive investigation
Time frame: Pre-transplant baseline; at 3- and 12-month protocol biopsies; and at the time of any indication biopsy after kidney transplantation
Flow-cytometric P-selectin (CD62-P) expression on platelets and soluble P-selectin levels in plasma will be measured before and after kidney transplantation and at the time of protocol or indication biopsy. These values will be compared between patients with and without biopsy-proven rejection to assess whether P-selectin can serve as a reliable marker of platelet activation associated with acute graft injury and support the development of a non-invasive diagnostic approach.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 10 Dec 2025.
- Individual participant dataSharing planned: No. It is a monocenter pilot study
Related trials for Platelet Aggregation
Not yet recruitingPhase 3
TicAgreLor Versus Placebo to Prevent Cerebral ISCHemia in anEuRysmal Low Grade SAH A Double Blinded Randomised Controlled Study
Subarachnoid Hemorrhage, Aneurysmal, Brain Ischemia
Active, not recruiting
Thromboelastography With Platelet Mapping to Guide Antiplatelet Therapy After Lower Extremity Revascularization
Thrombosis, Arterial Occlusive Diseases
Recruiting
Algorithm-based Tailoring of Dual Antiplatelet Therapy to Improve Outcomes Following Percutaneous Coronary Interventions
Percutaneous Coronary Intervention, Platelet Aggregation Inhibitors
Enrolling by invitationPhase 3
Selatogrel Outcome Study in Suspected Acute Myocardial Infarction
Acute Myocardial Infarction
Not yet recruiting
Cookies for Platelets
Blood Donation
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Matej Vnucak, ass prof, MD, PhD. study chair
University Hospital Martin and Jessenius Faculty of Medicine, Comenius University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Platelet Aggregation and Kidney Transplant Rejection, run by University Hospital, Martin at 1 site in Slovakia.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 10 Dec 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Slovakia. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Timea Blichova, MD (+421434203184, tc@unm.sk), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
To compare changes in platelet aggregation in patients before and after kidney transplantation (time frame: Pre-transplant baseline; 3 months post-transplant; 12 months post-transplant). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 10 Dec 2025.