Acanthocyte Sedimentation Rate as a Diagnostic Biomarker for Neuroacanthocytosis Syndromes: Experimental Evidence and Physical Justification

Abstract

(1) Background: Chorea-acanthocytosis and McLeod syndrome are the core diseases among the group of rare neurodegenerative disorders called neuroacanthocytosis syndromes (NASs). NAS patients have a variable number of irregularly spiky erythrocytes, so-called acanthocytes. Their detection is a crucial but error-prone parameter in the diagnosis of NASs, often leading to misdiagnoses. (2) Methods: We measured the standard Westergren erythrocyte sedimentation rate (ESR) of various blood samples from NAS patients and healthy controls. Furthermore, we manipulated the ESR by swapping the erythrocytes and plasma of different individuals, as well as replacing plasma with dextran. These measurements were complemented by clinical laboratory data and single-cell adhesion force measurements. Additionally, we followed theoretical modeling approaches. (3) Results: We show that the acanthocyte sedimentation rate (ASR) with a two-hour read-out is significantly prolonged in chorea-acanthocytosis and McLeod syndrome without overlap compared to the ESR of the controls. Mechanistically, through modern colloidal physics, we show that acanthocyte aggregation and plasma fibrinogen levels slow down the sedimentation. Moreover, the inverse of ASR correlates with the number of acanthocytes (R2=0.61, p=0.004). (4) Conclusions: The ASR/ESR is a clear, robust and easily obtainable diagnostic marker. Independently of NASs, we also regard this study as a hallmark of the physical view of erythrocyte sedimentation by describing anticoagulated blood in stasis as a percolating gel, allowing the application of colloidal physics theory.

The Erythrocyte Sedimentation Rate and Its Relation to Cell Shape and Rigidity of Red Blood Cells from Chorea-Acanthocytosis Patients in an Off-Label Treatment with Dasatinib

“…Since the ESR was proposed as a biomarker for NAS treatments [ 10 ], we performed ESR measurements technically identical with the initial report [ 10 ] and present the results in Figure 2 . This includes the sedimentation curves ( Figure 2 A), the sedimentation height at 2 h of sedimentation ( Figure 2 B) and examples of micrographs showing the RBC aggregate formation on a coverslip with a hematocrit in the 2D layer of approximately 45% ( Figure 2 C).…”

“…Due to mild gastrointestinal side effects [ 7 ], a second treatment period for almost six months with a reduced dose (from 100 to 80 mg/day) was performed accordingly. This was at a time when we initially started the measurements of the erythrocyte sedimentation rate (ESR) of neuroacanthocytosis syndrome (NAS) patients [ 10 ]. Therefore, we do not have pretreatment measurements but two different after-treatment time points.…”

“…This includes the sedimentation curves ( Figure 2 A), the sedimentation height at 2 h of sedimentation ( Figure 2 B) and examples of micrographs showing the RBC aggregate formation on a coverslip with a hematocrit in the 2D layer of approximately 45% ( Figure 2 C). We show the latter because hole size (the area of the ‘compartments’ between the RBCs) was shown to correlate with the ESR [ 10 ], and we refer to it below.…”

“…Measurements of clinical laboratory parameters were performed by standard methods in the Clinical Chemistry Laboratory of Saarland University Hospital (Homburg, Germany). Since a previous study identified both RBC properties and plasma constituents as contributors to a delayed ESR [ 10 ], we tested routine RBC and plasma parameters. RBC-related parameters tested were hematocrit, RBC number, hemoglobin concentration, mean cellular volume (MCV), mean cellular hemoglobin (MCH) and mean cellular hemoglobin concentration (MCHC).…”

“…The aim of this study was to test, as previously proposed [ 10 ], whether the ESR can be used as a biomarker to monitor treatment response of dasatinib and to explain the influence of particular plasma components and cellular properties on a putative change in the ESR.…”