Characterization of endothelial colony-forming cells from peripheral blood samples of adult horses.

OBJECTIVE: To isolate and characterize endothelial colony-forming cells (ECFCs; a subtype of endothelial progenitor cells) from peripheral blood samples of horses. SAMPLE: Jugular venous blood samples from 24 adult horses. PROCEDURES: Blood samples were cultured in endothelial cell growth medium. Isolated ECFCs were characterized by use of functional assays of fluorescence-labeled acetylated low-density lipoprotein (DiI-Ac-LDL) uptake and vascular tubule formation in vitro. Expression of endothelial (CD34, CD105, vascular endothelial growth factor receptor 2, and von Willebrand factor) and hematopoietic (CD14) cell markers was assessed through indirect immunofluorescence assay and flow cytometry. The number of passages before senescence was determined through serial evaluation of DiI-Ac-LDL uptake, vascular tubule formation, and cell doubling rates. RESULTS: Samples from 3 horses produced colonies at 12 ± 2.5 days with characteristic endothelial single layer cobblestone morphology and substantial outgrowth on expansion. Equine ECFCs formed vascular tubules in vitro and had uptake of DiI-Ac-LDL (74.9 ± 14.7% positive cells). Tubule formation and DiI-Ac-LDL uptake diminished by passage 5. Equine ECFCs tested positive for von Willebrand factor, vascular endothelial growth factor receptor 2, CD34, and CD105 with an immunofluorescence assay and for CD14 and CD105 via flow cytometry. CONCLUSIONS AND CLINICAL RELEVANCE: ECFCs can be isolated from peripheral blood of horses and have characteristics similar to those described for other species. These cells may have potential therapeutic use in equine diseases associated with ischemia or delayed vascularization.

Inaccuracies introduced by single width blood pressure cuffs.

Blood pressure cuff dimensions directly affect accuracy of blood pressure measurements. For accurate blood pressure measurements, the width of the cuff must be proportional to arm circumference. A cuff that is too narrow results in falsely high blood pressure values, and a cuff that is too wide results in falsely low values. Some blood pressure standards permit a single width cuff regardless of arm circumference. The purpose of this study was to evaluate whether 12 cm single width cuffs currently permitted by the British Hypertension Society (BHS) standard are sufficiently accurate to pass the Association for the Advancement of Medical Instrumentation (AAMI), BHS, and European Society of Hypertension (ESH) International Protocol (IP1) Working Group standards for accuracy. Each of 101 subjects was tested sequentially with both a single and a proportional width cuff in random order. Auscultatory blood pressure was determined by 2 observers using a double binaural stethoscope. Accuracy was determined by comparing the resulting differences with the AAMI, BHS, and IP1 standards for accuracy. The single width blood pressure cuff failed the AAMI accuracy standards for both systolic blood pressure on large arms and diastolic blood pressure on small and large arms, and overall. The single width cuffs, also, failed the BHS accuracy standards for diastolic BP. In conclusion, these single width cuffs could result in a significant number of people being misdiagnosed and mistreated for hypertension. Therefore, to avoid 'cuff hypertension' and 'cuff hypotension', the cuff width should be proportional to arm circumference.