Investigations of Megakaryocytes From Patients With Abnormal Platelet Vesicles
Data Collection
Blood Coagulation Disorders+3
+ Cardiovascular Diseases
+ Hematologic Diseases
Summary
Study start date: June 29, 2004
Actual date on which the first participant was enrolled.Congenital bleeding disorders characterized by abnormal platelet granules include Gray Platelet syndrome (GPS; defective alpha-granules), Hermansky-Pudlak syndrome (HPS; defective delta-granules), and combined alpha delta-storage pool deficiency (alpha delta-SPD). Other diseases associated with variable defects in platelet gamma-granules include Chediak-Higashi, Griscelli, Wiskott-Aldrich, and Thrombocytopenia Absent Radius syndromes. These disorders are models for the study of organelle formation in megakaryocytes and platelets. Characteristics of megakaryocytopoiesis in these disorders have not been investigated because megakaryocytes could not be cultured from patients in sufficient quantities for experimental purposes. Recent advances have made it possible to culture megakaryocytes using serum-free media supplemented with recombinant human thrombopoietin (TPO). Such cultured human megakaryocytes, amplified from bone marrow-derived CD34+ stem cells, synthesize and store organellar proteins and produce functional platelets. In this protocol, we plan to obtain bone marrow aspirates from 40 children and adults (ages 2 to 80 years) with GPS, HPS, and related disorders. Patients admitted to the NIH Clinical Center on specific disease-related protocols will be enrolled in this protocol during their routine 3-5 day visits. We will culture megakaryocytes from CD34+ stem cells isolated from bone marrow aspirates. Studies of cultured megakaryocytes will include evaluation of granule membrane and soluble proteins using fluorescent antibodies and immunoelectron microscopy and comparison of RNA and protein expression patterns between normal and patient cells. Precautions will be taken to prevent the primary risk of the bone marrow aspiration, i.e., prolonged bleeding at the aspiration site. Standard diagnostic studies on the bone marrow sample may reveal information that may directly benefit patients. However, the broader benefit of this study is the acquisition of a better understanding of the characteristics of functional platelet disorders and the process of intracellular vesicle formation.
Protocol
This section provides details of the study plan, including how the study is designed and what the study is measuring.3 patients to be enrolled
Total number of participants that the clinical trial aims to recruit.Eligibility
Researchers look for people who fit a certain description, called eligibility criteria: person's general health condition or prior treatments.Any sex
Biological sex of participants that are eligible to enroll.From 2 to 80 Years
Range of ages for which participants are eligible to join.Healthy volunteers not allowed
If individuals who are healthy and do not have the condition being studied can participate.Conditions
Pathology
Criteria
* INCLUSION CRITERIA: This protocol will include children and adults with a clinical diagnosis of GPS, HPS, isolated delta-SPD, combined alpha delta-SPD, Griscelli disease, Chediak Higashi syndrome, Wiskott Aldrich syndrome or Thrombocytopenia absent radius syndrome. Patients whose platelets exhibit abnormal intracellular vesicle morphology will also be eligible. EXCLUSION CRITERIA: Patients younger than 2 years and older than 80 years will be excluded. Patients with severe thrombocytopenia (fewer than 20 times 10(12) platelets/L) will be excluded.
Study Centers
These are the hospitals, clinics, or research facilities where the trial is being conducted. You can find the location closest to you and its status.This study has 1 location
National Institutes of Health Clinical Center, 9000 Rockville Pike
Bethesda, United StatesSee the location